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DEI Document - USD ($) $ in Millions	12 Months Ended
DEI Document - USD ($) $ in Millions	Dec. 31, 2018	Jan. 31, 2019	Jun. 29, 2018
Document Information [Abstract]
Entity Registrant Name	NuStar Energy L.P.
Entity Central Index Key	0001110805
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	ns
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Partnership Units Outstanding		107,278,252
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,800

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 13,644	$ 24,292
Accounts receivable, net of allowance for doubtful accounts of $9,412 and $9,948 as of December 31, 2018 and 2017, respectively	148,308	176,570
Receivable from related party	0	205
Inventories	22,713	26,857
Prepaid and other current assets	17,493	22,508
Total current assets	202,158	250,432
Property, plant and equipment, at cost	6,338,312	6,243,481
Accumulated depreciation and amortization	(2,049,690)	(1,942,548)
Property, plant and equipment, net	4,288,622	4,300,933
Intangible assets, net	733,056	784,479
Goodwill	1,036,976	1,097,475
Deferred income tax asset	0	233
Other long-term assets, net	88,328	101,681
Total assets	6,349,140	6,535,233
Current liabilities:
Accounts payable	143,121	145,932
Short-term debt	18,500	35,000
Current portion of long-term debt	0	349,990
Accrued interest payable	36,293	40,449
Accrued liabilities	101,993	61,578
Taxes other than income tax	19,083	14,385
Income tax payable	4,445	4,172
Total current liabilities	323,435	651,506
Long-term debt, less current portion	3,111,996	3,263,069
Deferred income tax liability	12,428	22,272
Other long-term liabilities	79,558	118,297
Total liabilities	3,527,417	4,055,144
Commitments and contingencies (Note 15)
Series D preferred limited partners (23,246,650 preferred units outstanding as of December 31, 2018) (Note 19)	563,992	0
Partners’ equity (Note 20):
Preferred limited partners (9,060,000 Series A preferred units, 15,400,000 Series B preferred units and 6,900,000 Series C preferred units outstanding as of December 31, 2018 and 2017)	756,301	756,603
Common limited partners (107,225,156 and 93,176,683 common units outstanding as of December 31, 2018 and 2017, respectively)	1,556,308	1,770,587
General partner	0	37,826
Accumulated other comprehensive loss	(54,878)	(84,927)
Total partners' equity	2,257,731	2,480,089
Total liabilities, mezzanine equity and partners’ equity	$ 6,349,140	$ 6,535,233

CONSOLIDATED BALANCE SHEETS Non-Printing - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 9,412	$ 9,948
Series D preferred units outstanding	23,246,650	0
Limited partners common units outstanding (in units)	107,225,156	93,176,683
Series A Preferred Limited Partner [Member]
Preferred units outstanding	9,060,000	9,060,000
Series B Preferred Limited Partner [Member]
Preferred units outstanding	15,400,000	15,400,000
Series C Preferred Limited Partner [Member]
Preferred units outstanding	6,900,000	6,900,000

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Total revenues	$ 1,961,757	$ 1,814,019	$ 1,756,682
General and administrative expenses (excluding depreciation and amortization expense):
Third parties	106,200	112,240	88,324
Related party	0	0	10,493
Total general and administrative expenses	106,200	112,240	98,817
Other depreciation and amortization expense	8,875	8,698	8,519
Total costs and expenses	1,598,194	1,477,741	1,397,573
Operating income	363,563	336,278	359,109
Interest expense, net	(186,237)	(173,083)	(138,350)
Other income (expense), net	39,876	(5,294)	(58,783)
Income before income tax expense	217,202	157,901	161,976
Income tax expense	11,408	9,937	11,973
Net income	$ 205,794	$ 147,964	$ 150,003
Basic net (loss) income per common unit (Note 21)	$ (2.77)	$ 0.64	$ 1.27
Diluted net (loss) income per common unit (Note 21)	$ (2.77)	$ 0.64	$ 1.27
Basic weighted-average common units outstanding	99,490,495	88,825,964	78,080,484
Diluted weighted-average common units outstanding	99,531,172	88,825,964	78,113,002
Service [Member]
Revenues:
Total revenues	$ 1,206,981	$ 1,128,726	$ 1,083,165
Operating expenses (excluding depreciation and amortization expense):
Third parties	488,174	449,670	426,686
Related party	0	0	21,681
Total operating expenses	488,174	449,670	448,367
Depreciation and amortization expense	288,999	255,534	208,217
Total costs associated with service revenues/Cost of product sales	777,173	705,204	656,584
Product [Member]
Revenues:
Total revenues	754,776	685,293	673,517
Operating expenses (excluding depreciation and amortization expense):
Total costs associated with service revenues/Cost of product sales	$ 705,946	$ 651,599	$ 633,653

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	$ 205,794	$ 147,964	$ 150,003
Other comprehensive income (loss):
Foreign currency translation adjustment									4,304	17,466	(8,243)
Net gain (loss) on pension and other postretirement benefit adjustments, net of income tax (expense) benefit of ($94), $184 and $60									2,334	(6,170)	(2,850)
Net gain (loss) on cash flow hedges									23,411	(2,046)	5,710
Total other comprehensive income (loss)									30,049	9,250	(5,383)
Comprehensive income									235,843	157,214	144,620
Income tax (expense) benefit on pension and other postretirement benefit plan adjustments									$ (94)	$ 184	$ 60

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income	$ 205,794	$ 147,964	$ 150,003
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	297,874	264,232	216,736
Unit-based compensation expense	12,004	8,132	7,579
Amortization of debt related items	7,388	6,147	7,477
Loss from sale of European operations	43,366	0	0
(Gain) loss from sale or disposition of assets	(2,094)	4,984	64
Gain from insurance recoveries	(78,756)	0	0
Impairment loss	0	0	58,655
Deferred income tax expense (benefit)	2,043	6	(469)
Changes in current assets and current liabilities (Note 22)	78,262	(26,493)	3,716
(Increase) decrease in other long-term assets	(3,029)	943	18,021
(Decrease) increase in other long-term liabilities	(17,832)	2,414	(23,408)
Other, net	(813)	(1,530)	(1,613)
Net cash provided by operating activities	544,207	406,799	436,761
Cash Flows from Investing Activities:
Capital expenditures	(457,452)	(384,638)	(204,358)
Change in accounts payable related to capital expenditures	(7,683)	36,903	(11,063)
Acquisitions	(37,502)	(1,461,719)	(95,657)
Proceeds from Axeon term loan	0	110,000	0
Proceeds from insurance recoveries	78,419	977	0
Proceeds from sale of European operations	266,740	0	0
Proceeds from sale or disposition of assets	3,700	2,036	0
Net cash used in investing activities	(153,778)	(1,696,441)	(311,078)
Cash Flows from Financing Activities:
Proceeds from long-term debt borrowings	1,254,153	1,465,767	752,729
Proceeds from short-term debt borrowings	618,500	1,051,000	654,000
Proceeds from note offering, net of issuance costs	0	543,333	0
Long-term debt repayments	(1,746,776)	(1,417,539)	(772,152)
Short-term debt repayments	(635,000)	(1,070,000)	(684,000)
Proceeds from issuance of Series D preferred units	590,000	0	0
Payment of issuance costs for Series D preferred units	(34,203)	0	0
Proceeds from issuance of other preferred units, net of issuance costs	0	538,560	218,400
Proceeds from issuance of common units, net of issuance costs	10,000	643,878	27,710
Contributions from general partner	204	13,737	680
Distributions to preferred unitholders	(90,670)	(38,833)	0
Distributions to common unitholders and general partner	(300,777)	(446,306)	(392,962)
Cash consideration for Merger (Note 4)	(67,795)	0	0
Proceeds from termination of interest rate swaps	8,048	0	0
Increase (decrease) in cash book overdrafts	2,935	1,736	(11,237)
Other, net	(8,486)	(9,061)	(4,492)
Net cash provided by (used in) financing activities	(399,867)	1,276,272	(211,324)
Effect of foreign exchange rate changes on cash	(1,210)	1,720	2,721
Net decrease in cash and cash equivalents	(10,648)	(11,650)	(82,920)
Cash and cash equivalents as of the beginning of the period	24,292	35,942	118,862
Cash and cash equivalents as of the end of the period	$ 13,644	$ 24,292	$ 35,942

CONSOLIDATED STATEMENTS OF PARTNERS' EQUITY AND MEZZANINE EQUITY - USD ($) $ in Thousands	Total	AOCI [Member]	Preferred Limited Partner [Member]	Common Limited Partner [Member]	General Partner [Member]	Series D Preferred Limited Partner [Member]
Partners' capital - beginning balance at Dec. 31, 2015	$ 1,609,844	$ (88,794)	$ 0	$ 1,661,900	$ 36,738
Temporary equity - beginning balance at Dec. 31, 2015	0
Partners' capital and temporary equity - beginning balance at Dec. 31, 2015	1,609,844
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	150,003	0	1,925	102,580	45,498
Net income, excluding portion attributable to temporary equity	150,003
Net income, temporary equity	0
Other comprehensive income (loss)	(5,383)	(5,383)	0	0	0
Cash distributions to partners	(394,887)	0	(1,925)	(341,798)	(51,164)
Distributions to partners, temporary equity						$ 0
Cash distributions to partners, including temporary equity	(394,887)
Issuance of units, including contribution from general partner	28,285	0	218,400	27,710	575
Unit-based compensation	5,355	0	0	5,250	105
Series D Preferred Unit accretion, common (refer to Note 19 for discussion)				0
Partners' capital - ending balance at Dec. 31, 2016	1,611,617	(94,177)	218,400	1,455,642	31,752
Temporary equity - ending balance at Dec. 31, 2016	0
Partners' capital and temporary equity - ending balance at Dec. 31, 2016	1,611,617
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	147,964	0	40,448	60,610	46,906
Net income, excluding portion attributable to temporary equity	147,964
Net income, temporary equity	0
Other comprehensive income (loss)	9,250	9,250	0	0	0
Cash distributions to partners	(486,754)	0	(40,448)	(391,737)	(54,569)
Distributions to partners, temporary equity						0
Cash distributions to partners, including temporary equity	(486,754)
Issuance of units, including contribution from general partner	657,475	0	538,560	643,878	13,597
Unit-based compensation	2,656	0	0	2,516	140
Series D Preferred Unit accretion, common (refer to Note 19 for discussion)				0
Other	(679)	0	(357)	(322)	0
Other, temporary equity						0
Other, including temporary equity	(679)
Partners' capital - ending balance at Dec. 31, 2017	2,480,089	(84,927)	756,603	1,770,587	37,826
Temporary equity - ending balance at Dec. 31, 2017	0
Partners' capital and temporary equity - ending balance at Dec. 31, 2017	2,480,089
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	205,794	0	64,091	110,788	2,466
Net income, excluding portion attributable to temporary equity	177,345
Net income, temporary equity						28,449
Other comprehensive income (loss)	30,049	30,049	0	0	0
Cash distributions to partners	(364,868)	0	(64,091)	(286,398)	(14,379)
Distributions to partners, temporary equity						28,449
Cash distributions to partners, including temporary equity	(393,317)
Issuance of units, including contribution from general partner	10,204	0	0	10,000	204
Issuance of Series D preferred units	555,797					555,797
Unit-based compensation	7,925	0	0	7,925	0
Adjustments related to the Merger (refer to Note 4 for discussion)	(67,972)	0	0	(41,973)	(25,999)
Series D Preferred Unit accretion, common (refer to Note 19 for discussion)	(8,195)	0	0	(8,195)	0
Series D Preferred Unit accretion, preferred (refer to Note 19 for discussion)						(8,195)
Series D Preferred Unit accretion, total (refer to Note 19 for discussion)	0
Other	(6,846)	0	(302)	(6,426)	(118)
Other, temporary equity						$ 0
Other, including temporary equity	(6,846)
Partners' capital - ending balance at Dec. 31, 2018	2,257,731	$ (54,878)	$ 756,301	$ 1,556,308	$ 0
Temporary equity - ending balance at Dec. 31, 2018	563,992
Partners' capital and temporary equity - ending balance at Dec. 31, 2018	$ 2,821,723

ORGANIZATION AND OPERATIONS	12 Months Ended
ORGANIZATION AND OPERATIONS	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION AND OPERATIONS	ORGANIZATION AND OPERATIONS Organization NuStar Energy L.P. (NYSE: NS) is engaged in the transportation of petroleum products and anhydrous ammonia, and the terminalling, storage and marketing of petroleum products. Unless otherwise indicated, the terms “NuStar Energy,” “NS,” “the Partnership,” “we,” “our” and “us” are used in this report to refer to NuStar Energy L.P., to one or more of our consolidated subsidiaries or to all of them taken as a whole. As a result of the merger described below, NuStar GP Holdings, LLC (NuStar GP Holdings or NSH), which indirectly owns our general partner, became a wholly owned subsidiary of ours on July 20, 2018. Recent Developments Sale of European Operations. On November 30, 2018, we sold our European operations to Inter Terminals, Ltd. for approximately $270.0 million. The operations sold include six liquids storage terminals in the United Kingdom and one facility in Amsterdam. We recognized a non-cash loss of $43.4 million related to the sale in “Other income (expense), net” on our consolidated statement of income for the year ended December 31, 2018. Please refer to Note 5 for further discussion of the sale. Merger. On July 20, 2018, we completed the merger of NSH with a subsidiary of NS. Under the terms of the merger agreement, NSH unitholders received 0.55 of a common unit representing a limited partner interest in NS in exchange for each NSH unit owned at the effective time of the merger. Please refer to Note 4 for further discussion of the merger. Issuances of Units. In June and July of 2018, we issued 23,246,650 Series D Cumulative Convertible Preferred Units (Series D Preferred Units) at a price of $25.38 per unit in a private placement for net proceeds of $555.8 million. See Note 19 for further discussion. On June 29, 2018, we also issued 413,736 common units at a price of $24.17 per unit to William E. Greehey, Chairman of the Board of Directors of NuStar GP, LLC. Hurricane Activity. In the third quarter of 2017, several of our facilities were affected by the hurricanes in the Caribbean and Gulf of Mexico, including our St. Eustatius terminal, which experienced the most damage and was temporarily shut down. The damage caused by the Caribbean hurricane resulted in lower revenues for our bunker fuel operations in our fuels marketing segment and lower throughput and associated handling fees in our storage segment in 2017 and in the first quarter of 2018. In 2017, we recorded a $5.0 million loss in “Other income (expense), net” in the consolidated statements of income for property damage at the terminal, which represents the amount of our property deductible under our insurance policy, and we received $12.5 million of insurance proceeds, of which $3.8 million was for business interruption. In January 2018, we received $87.5 million of insurance proceeds in settlement of our property damage claim for our St. Eustatius terminal, of which $9.1 million related to business interruption. Proceeds from business interruption insurance are included in “Operating expenses” in the consolidated statements of income and in “Cash flows from operating activities” in the consolidated statements of cash flows. We recorded a $78.8 million gain in “Other income (expense), net” in the consolidated statements of income in the first quarter of 2018 for the amount by which the insurance proceeds exceeded our expenses incurred during the period. Although the repairs are not complete, we expect that the costs to repair the property damage at the terminal will not exceed the amount of insurance proceeds received. Other Events Navigator Acquisition and Financing Transactions. On May 4, 2017, we acquired Navigator Energy Services, LLC for approximately $1.5 billion (the Navigator Acquisition). In order to fund the purchase price, we issued 14,375,000 common units for net proceeds of $657.5 million, issued $550.0 million of 5.625% senior notes for net proceeds of $543.3 million and issued 15,400,000 of our 7.625% Series B Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units (Series B Preferred Units) for net proceeds of $371.8 million. Please refer to Notes 5, 13 and 20 for further discussion. Axeon Term Loan. On February 22, 2017, we settled and terminated the $190.0 million term loan to Axeon Specialty Products, LLC (the Axeon Term Loan), pursuant to which we also provided credit support, such as guarantees, letters of credit and cash collateral, as applicable, of up to $125.0 million to Axeon Specialty Products, LLC (Axeon). We received $110.0 million in settlement of the Axeon Term Loan, and our obligation to provide ongoing credit support to Axeon ceased. Please refer to Note 18 for further discussion of the Axeon Term Loan and related credit support. Employee Transfer from NuStar GP, LLC. On March 1, 2016, NuStar GP, LLC, the general partner of our general partner and a wholly owned subsidiary of NuStar GP Holdings, transferred and assigned to NuStar Services Company LLC (NuStar Services Co), a wholly owned subsidiary of NuStar Energy, all of NuStar GP, LLC’s employees and related benefit plans, programs, contracts and policies (the Employee Transfer). As a result of the Employee Transfer, we pay employee costs directly and sponsor the Fifth Amended and Restated 2000 Long-Term Incentive Plan (the 2000 LTIP) and other employee benefit plans. Please refer to Note 4 for further discussion of the Employee Transfer and our related party agreements, Note 23 for a discussion of our employee benefit plans and Note 24 for a discussion of our long-term incentive plans. Operations We conduct our operations through our subsidiaries, primarily NuStar Logistics, L.P. (NuStar Logistics) and NuStar Pipeline Operating Partnership L.P. (NuPOP). We have three business segments: pipeline, storage and fuels marketing. Pipeline. We own 3,130 miles of refined product pipelines and 2,070 miles of crude oil pipelines, as well as approximately 5.0 million barrels of storage capacity, which comprise our Central West System. In addition, we own 2,600 miles of refined product pipelines, consisting of the East and North Pipelines, and a 2,000-mile ammonia pipeline, which comprise our Central East System. The East and North Pipelines have storage capacity of approximately 7.3 million barrels. We charge tariffs on a per barrel basis for transporting refined products, crude oil and other feedstocks in our refined product and crude oil pipelines and on a per ton basis for transporting anhydrous ammonia in the Ammonia Pipeline. Storage. We own terminal and storage facilities in the United States, Canada, Mexico and St. Eustatius in the Caribbean Netherlands, with approximately 75.8 million barrels of storage capacity. Our terminal and storage facilities provide storage, handling and other services on a fee basis for petroleum products, crude oil, specialty chemicals and other liquids. Fuels Marketing. Prior to the third quarter of 2017, our fuels marketing operations involved the purchase of crude oil, fuel oil, bunker fuel, fuel oil blending components and other refined products for resale. We ceased marketing crude oil in the second quarter of 2017 and exited our heavy fuels trading operations in the third quarter of 2017. These actions were in line with our goal of reducing our exposure to commodity margins, and instead focusing on our core, fee-based pipeline and storage segments. The remaining operations in our fuels marketing segment are our bunkering operations at our St. Eustatius and Texas City terminals, as well as certain of our blending operations. The results of operations for the fuels marketing segment depend largely on the margin between our cost and the sales prices of the products we market. Therefore, the results of operations for this segment are more sensitive to changes in commodity prices compared to the operations of the pipeline and storage segments. Since our fuels marketing operations expose us to commodity price risk, we enter into derivative instruments to mitigate the effect of commodity price fluctuations on our operations. The derivative instruments we use consist primarily of commodity futures and swap contracts.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Consolidation

The accompanying consolidated financial statements represent the consolidated operations of the Partnership and our subsidiaries. Inter-partnership balances and transactions have been eliminated in consolidation. The operations of certain pipelines and terminals in which we own an undivided interest are proportionately consolidated in the accompanying consolidated financial statements.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (GAAP) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. On an ongoing basis, management reviews its estimates based on currently available information. Management may revise estimates due to changes in facts and circumstances.

Cash and Cash Equivalents

Cash equivalents are all highly liquid investments with an original maturity of three months or less when acquired.

Accounts Receivable

Trade receivables are carried at original invoice amount. We extend credit terms to certain customers after review of various credit indicators, including the customer’s credit rating. Outstanding customer receivable balances are regularly reviewed for possible non-payment indicators and allowances for doubtful accounts are recorded based upon management’s estimate of collectability at the time of its review.

Inventories

Inventories consist of petroleum products, materials and supplies. Inventories, except those associated with a qualifying fair value hedge, are valued at the lower of cost or net realizable value. Cost is determined using the weighted-average cost method. Our inventory, other than materials and supplies, consists of one end-product category, petroleum products, which we include in the fuels marketing segment. Accordingly, we determine lower of cost or net realizable value adjustments on an aggregate basis. Inventories associated with qualifying fair value hedges are valued at current market prices. Materials and supplies are valued at the lower of average cost or net realizable value.

Property, Plant and Equipment

We record additions to property, plant and equipment, including reliability and strategic capital expenditures, at cost. Repair and maintenance costs associated with existing assets that are minor in nature and do not extend the useful life of existing assets are charged to operating expenses as incurred. Depreciation of property, plant and equipment is recorded on a straight-line basis over the estimated useful lives of the related assets. When property or equipment is retired, sold or otherwise disposed of, the difference between the carrying value and the net proceeds is recognized in “Other income (expense), net” in the consolidated statements of income in the year of disposition.

We capitalize overhead costs and interest costs incurred on funds used to construct property, plant and equipment while the asset is under construction. The overhead costs and capitalized interest are recorded as part of the asset to which they relate and are amortized over the asset’s estimated useful life as a component of depreciation expense.

Goodwill

We assess goodwill for impairment annually on October 1, or more frequently if events or changes in circumstances indicate it might be impaired. We have the option to first assess qualitative factors to determine whether it is necessary to perform a quantitative goodwill impairment test. We performed a quantitative goodwill impairment test as of October 1, 2018 and 2017, and determined that no impairment charges existed.

We recognize an impairment of goodwill if the carrying value of goodwill exceeds its estimated fair value. In order to estimate the fair value of goodwill, management must make certain estimates and assumptions that affect the total fair value of the reporting unit including, among other things, an assessment of market conditions, projected cash flows, discount rates and growth rates. Management’s estimates of projected cash flows related to the reporting unit include, but are not limited to, future earnings of the reporting unit, assumptions about the use or disposition of the asset, estimated remaining life of the asset, and future expenditures necessary to maintain the asset’s existing service potential.

We calculate the estimated fair value of each of our reporting units using a weighted-average of values calculated using an income approach and a market approach. The income approach involves estimating the fair value of each reporting unit by discounting its estimated future cash flows using a discount rate that would be consistent with a market participant’s assumption. The market approach bases the fair value measurement on information obtained from observed stock prices of public companies and recent merger and acquisition transaction data of comparable entities.

Our reporting units to which goodwill has been allocated consist of the following:


•	crude oil pipelines;


•	refined product pipelines;


•	terminals, excluding our St. Eustatius and Point Tupper facilities and our refinery crude storage tanks; and


•	bunkering activity at our St. Eustatius and Point Tupper facilities.

The quantitative impairment test for goodwill consists of a two-step process. Step 1 compares the fair value of the reporting unit to its carrying value including goodwill. The carrying value of each reporting unit equals the total identified assets (including goodwill) less the sum of each reporting unit’s identified liabilities. We used reasonable and supportable methods to assign the assets and liabilities to the appropriate reporting units in a consistent manner. If the carrying value exceeds fair value, there is a potential impairment and step 2 must be performed to determine the amount of goodwill impairment. Step 2 compares the carrying value of the reporting unit’s goodwill to its implied fair value using a hypothetical allocation of the reporting unit’s fair value. If the goodwill carrying value exceeds its implied fair value, the excess is reported as impairment.

Although we determined that no impairment charges resulted from our October 1, 2018 impairment assessment, the fair value of the reporting unit that conducts bunkering activity at our St. Eustatius and Point Tupper facilities (the Statia Bunkering Reporting Unit) exceeded its carrying value by approximately 2%. The goodwill associated with the Statia Bunkering Reporting Unit totaled $31.1 million as of December 31, 2018. Our estimate of the fair value of the Statia Bunkering Reporting Unit is sensitive to typical valuation assumptions, particularly future earnings and cash flows. Recently, the earnings of our Statia Bunkering Reporting Unit have declined compared to historical norms, mostly due to the continued impact from hurricanes that damaged much of the infrastructure in the Caribbean. Our estimates assume the earnings of the Statia Bunkering Reporting Unit return to those historical levels in the near term. However, if there is a prolonged reduction in our earnings from the lingering effect described above, or other factors that result in a slower than anticipated recovery in our earnings, it could result in a reduction of our estimated fair value of the Statia Bunkering Reporting Unit to an amount less than its carrying value. We will continue to monitor the business and consider additional interim analysis of goodwill as appropriate.

Impairment of Long-Lived Assets

We review long-lived assets, including property, plant and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. We evaluate recoverability using undiscounted estimated net cash flows generated by the related asset or asset group. If the results of that evaluation indicate that the undiscounted cash flows are less than the carrying amount of the asset (i.e., the asset is not recoverable) we perform an impairment analysis. If our intent is to hold the asset for continued use, we determine the amount of impairment as the amount by which the net carrying value exceeds its fair value. If our intent is to sell the asset, and the criteria required to classify an asset as held for sale are met, we determine the amount of impairment as the amount by which the net carrying amount exceeds its fair value less costs to sell. We believe that the carrying amounts of our long-lived assets as of December 31, 2018 are recoverable.

Income Taxes

We are a limited partnership and generally are not subject to federal or state income taxes. Accordingly, our taxable income or loss, which may vary substantially from income or loss reported for financial reporting purposes, is generally included in the federal and state income tax returns of our partners. For transfers of publicly held common units subsequent to our initial public offering, we have made an election permitted by Section 754 of the Internal Revenue Code (the Code) to adjust the common unit purchaser’s tax basis in our underlying assets to reflect the purchase price of the units. This results in an allocation of taxable income and expenses to the purchaser of the common units, including depreciation deductions and gains and losses on sales of assets, based upon the new unitholder’s purchase price for the common units.

We conduct certain of our operations through taxable wholly owned corporate subsidiaries. We account for income taxes related to our taxable subsidiaries using the asset and liability method. Under this method, we recognize deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. We measure deferred taxes using enacted tax rates expected to apply to taxable income in the year those temporary differences are expected to be recovered or settled.

We recognize a tax position if it is more likely than not that the tax position will be sustained, based on the technical merits of the position, upon examination. We record uncertain tax positions in the financial statements at the largest amount of benefit that is more likely than not to be realized. We had no unrecognized tax benefits as of December 31, 2018 and 2017.

NuStar Energy and certain of its subsidiaries file income tax returns in the U.S. federal jurisdiction and various state and foreign jurisdictions. For U.S. federal and state purposes, as well as for our major non-U.S. jurisdictions, tax years subject to examination are 2015 through 2017, according to standard statute of limitations.

Asset Retirement Obligations

We record a liability for asset retirement obligations at the fair value of the estimated costs to retire a tangible long-lived asset at the time we incur that liability, which is generally when the asset is purchased, constructed or leased, when we have a legal obligation to incur costs to retire the asset and when a reasonable estimate of the fair value of the obligation can be made. If a reasonable estimate cannot be made at the time the liability is incurred, we record the liability when sufficient information is available to estimate the fair value.

We have asset retirement obligations with respect to certain of our assets due to various legal obligations to clean and/or dispose of those assets at the time they are retired. However, these assets can be used for an extended and indeterminate period of time as long as they are properly maintained and/or upgraded. It is our practice and current intent to maintain our assets and continue making improvements to those assets based on technological advances. As a result, we believe that our assets have indeterminate lives for purposes of estimating asset retirement obligations because dates or ranges of dates upon which we would retire these assets cannot reasonably be estimated at this time. When a date or range of dates can reasonably be estimated for the retirement of any asset, we estimate the costs of performing the retirement activities and record a liability for the fair value of these costs.

We also have legal obligations in the form of leases and right-of-way agreements, which require us to remove certain of our assets upon termination of the agreement. However, these lease or right-of-way agreements generally contain automatic renewal provisions that extend our rights indefinitely or we have other legal means available to extend our rights. We have recorded liabilities of $0.2 million and $0.7 million as of December 31, 2018 and 2017, respectively, which are included in “Other long-term liabilities” in the consolidated balance sheets, for conditional asset retirement obligations related to the retirement of terminal assets with lease and right-of-way agreements.

Environmental Remediation Costs

Environmental remediation costs are expensed and an associated accrual established when site restoration and environmental remediation and cleanup obligations are either known or considered probable and can be reasonably estimated. These environmental obligations are based on estimates of probable undiscounted future costs using currently available technology and applying current regulations, as well as our own internal environmental policies. The environmental liabilities have not been reduced by possible recoveries from third parties. Environmental costs include initial site surveys, costs for remediation and restoration and ongoing monitoring costs, as well as fines, damages and other costs, when estimable. Adjustments to initial estimates are recorded, from time to time, to reflect changing circumstances and estimates based upon additional information developed in subsequent periods.

Product Imbalances

We incur product imbalances as a result of variances in pipeline meter readings and volume fluctuations due to pressure and temperature changes. Pursuant to the new revenue recognition standard we adopted January 1, 2018, we no longer recognize the fair value of product imbalances on our consolidated balance sheets. Prior to adoption, we used quoted market prices as of the reporting date to value our assets and liabilities related to product imbalances. Product imbalance liabilities were included in “Accrued liabilities” and product imbalance assets were included in “Other current assets” in the consolidated balance sheets.

Revenue Recognition

Revenue-Generating Activities. Revenues for the pipeline segment are derived from interstate and intrastate pipeline transportation of refined products, crude oil and anhydrous ammonia and the applicable pipeline tariff.

Revenues for the storage segment include fees for tank storage agreements, whereby a customer agrees to pay for a certain amount of storage in a tank over a period of time (storage terminal revenues), and throughput agreements, whereby a customer pays a fee per barrel for volumes moving through our terminals (throughput terminal revenues). Our terminals also provide blending, additive injections, handling and filtering services for which we charge additional fees, and certain of our facilities charge fees to provide marine services such as pilotage, tug assistance, line handling, launch service, emergency response services and other ship services (all of which are considered optional services).

Revenues for the fuels marketing segment are derived from the sale of petroleum products.

Within our pipeline and storage segments, we provide services on uninterruptible and interruptible bases. Uninterruptible services within our pipeline segment typically result from contracts that contain take-or-pay minimum volume commitments (MVCs) from the customer. Contracts with MVCs obligate the customer to pay for that minimum amount. If a customer fails to meet its MVC for the applicable service period, the customer is obligated to pay a deficiency fee based upon the shortfall between the actual volumes transported or stored and the MVC for that service period (deficiency payments). In exchange, those contracts with MVCs obligate us to stand ready to transport volumes up to the customer’s MVC.

Within our storage segment, uninterruptible services arise from contracts containing a fixed monthly fee for the portion of storage capacity reserved by the customer. These contracts require that the customer pay the fixed monthly fee, regardless of whether or not it uses our storage facility (i.e., take-or-pay obligation), and that we stand ready to store that volume.

Interruptible services within our pipeline and storage segments are generally provided when and to the extent we determine the requested capacity is available. The customer typically pays a per-unit rate for the actual quantities of services it receives.

Adoption of ASC Topic 606. On January 1, 2018, we adopted Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (ASC Topic 606) using the modified retrospective method and applied ASC Topic 606 to all revenue contracts with customers. After identifying a contract with a customer, ASC Topic 606 requires us to (i) identify the performance obligations in the contract; (ii) determine the transaction price; (iii) allocate the transaction price to the performance obligations; and (iv) recognize revenue when or as we satisfy a performance obligation. For the majority of our contracts, we recognize revenue in the amount to which we have a right to invoice. Generally, payment terms do not exceed 30 days.

Performance Obligations. The majority of our contracts contain a single performance obligation. For our pipeline segment, the single performance obligation encompasses multiple activities necessary to deliver our customers’ products to their destinations. Typically, we satisfy this performance obligation over time as the product volume is delivered in or out of the pipelines. Similarly, the performance obligation for our storage segment consists of multiple activities necessary to receive, store and deliver our customers’ products. We typically satisfy this performance obligation over time as the product volume is delivered in or out of the tanks (for throughput terminal revenues) or with the passage of time (for storage terminal revenues). Certain of our pipeline segment customer contracts include an incentive pricing structure, which provides a discounted rate for the remainder of the contract once the customer exceeds a cumulative volume. The ability to receive discounted future services represents a material right to the customer, which results in a second performance obligation in those contracts.

Product sales contracts associated with our fuels marketing segment generally include a single performance obligation to deliver specified volumes of a commodity, which we satisfy at a point in time, when the product is delivered and the customer obtains control of the commodity.

Optional services do not provide a material right to the customer, and are not considered a separate performance obligation in the contract. If and when a customer elects an optional service, it becomes part of the existing performance obligation.

Transaction Price. For uninterruptible services, we determine the transaction price at contract inception based on the guaranteed minimum amount of revenue over the term of the contract. For interruptible services and optional services, we determine the transaction price based on our right to invoice the customer for the value of services provided to the customer for the applicable period.

In certain instances, our customers reimburse us for capital projects, in arrangements referred to as contributions in aid of construction, or CIAC. Typically, in these instances, we receive upfront payments for future services, which are included in the transaction price of the underlying service contract.

We collect taxes on certain revenue transactions to be remitted to governmental authorities, which may include sales, use, value-added and some excise taxes. These taxes are not included in the transaction price and are, therefore, excluded from revenues.

Allocation of Transaction Price. We allocate the transaction price to the single performance obligation that exists in the vast majority of our contracts with customers. For the few contracts that have a second performance obligation, such as those that include an incentive pricing structure, we calculate an average rate based on the estimated total volumes to be delivered over the term of the contract and the resulting estimated total revenue to be billed using the applicable rates in the contract. We allocate the transaction price to the two performance obligations by applying the average rate to product volumes as they are delivered to the customer over the term of the contract. Determining the timing and amount of volumes subject to these incentive pricing contracts requires judgment that can impact the amount of revenue allocated to the two separate performance obligations. We base our estimates on our analysis of expected future production information available from our customers or other sources, which we update at least quarterly.

Some of our MVC contracts include provisions that allow the customer to apply deficiency payments to future service periods (the carryforward period). In those instances, we have not satisfied our performance obligation as we still have the obligation to perform those services, subject to contractual and/or capacity constraints, at the customer’s request. At least quarterly, we assess the customer’s ability to utilize any deficiency payments during the carryforward period. If we receive a deficiency payment from a customer that we expect the customer to utilize during the carryforward period, we defer that amount as a contract liability. We will consider the performance obligation satisfied and allocate any deferred deficiency payments to our performance obligation when the customer utilizes the deficiency payment, the carryforward period ends or we determine the customer cannot or will not utilize the deficiency payment (i.e. breakage). If our contract does not allow the customer to apply deficiency payments to future service periods, we allocate the deficiency payment to the already satisfied portion of the performance obligation.

Income Allocation

Our partnership agreement contains provisions for the allocation of net income to the unitholders and, prior to the merger with our general partner, to the general partner. Our net income for each quarterly reporting period is first allocated to the preferred limited partner unitholders in an amount equal to the earned distributions for the respective reporting period and, prior to the merger, then to the general partner in an amount equal to the general partner’s incentive distribution calculated based upon the declared distribution for the respective reporting period. We allocate the remaining net income or loss among the common unitholders. Prior to the merger, we allocated the remaining net income or loss among the common unitholders (98%) and general partner (2%). See Note 4 for further discussion of the merger and Note 20 for the calculation of net income applicable to the general partner prior to the merger.

Basic and Diluted Net (Loss) Income Per Common Unit

Basic and diluted net (loss) income per common unit are determined pursuant to the two-class method. Under this method, all earnings are allocated to our limited partners and participating securities based on their respective rights to receive distributions earned during the period. Participating securities include restricted units awarded under our long-term incentive plans and, prior to the merger with our general partner, included our general partner’s interest.

We compute basic net (loss) income per common unit by dividing net (loss) income attributable to our common limited partners by the weighted-average number of common units outstanding during the period. We compute diluted net (loss) income per common unit by dividing net (loss) income attributable to our common limited partners by the sum of (i) the weighted-average number of common units outstanding during the period and (ii) the effect of dilutive potential common units outstanding during the period. Dilutive potential common units include contingently issuable performance units awarded and the Series D Preferred Units. See Note 24 for additional information on our performance units, Note 19 for additional information on our Series D Preferred Units and Note 21 for the calculation of basic and diluted net (loss) income per common unit.

Derivative Financial Instruments

We formally document all relationships between hedging instruments and hedged items. This process includes identification of the hedging instrument and the hedged transaction, the nature of the risk being hedged and how the hedging instrument’s effectiveness will be assessed. To qualify for hedge accounting, at inception of the hedge we assess whether the derivative instruments that are used in our hedging transactions are expected to be highly effective in offsetting changes in cash flows or the fair value of the hedged items. Throughout the designated hedge period and at least quarterly, we assess whether the derivative instruments are highly effective and continue to qualify for hedge accounting. To assess the effectiveness of the hedging relationship both prospectively and retrospectively, we use regression analysis to calculate the correlation of the changes in the fair values of the derivative instrument and related hedged item.

We record commodity derivative instruments in the consolidated balance sheets at fair value. We recognize mark-to-market adjustments for derivative instruments designated and qualifying as fair value hedges (Fair Value Hedges) and the related change in the fair value of the associated hedged physical inventory or firm commitment within “Cost of product sales.” For derivative instruments that have associated underlying physical inventory but do not qualify for hedge accounting (Economic Hedges and Other Derivatives), we record the mark-to-market adjustments in “Cost of product sales.”

Under the terms of our forward-starting interest rate swap agreements, we pay a fixed rate and receive a variable rate. We entered into the forward-starting swaps in order to hedge the risk of changes in the interest payments attributable to changes in the benchmark interest rate during the period from the effective date of the swap to the issuance of the forecasted debt. For forward-starting interest rate swaps designated and qualifying as cash flow hedges (Cash Flow Hedges), we recognize the fair value of each interest rate swap in the consolidated balance sheets. We record the effective portion of mark-to-market adjustments as a component of accumulated other comprehensive income (loss) (AOCI), and any hedge ineffectiveness is recognized immediately in “Interest expense, net.” The amount accumulated in AOCI is amortized into “Interest expense, net” as the forecasted interest payments occur or if the interest payments are probable not to occur.

We classify cash flows associated with our derivative instruments as operating cash flows in the consolidated statements of cash flows, except for receipts or payments associated with terminated forward-starting interest rate swap agreements, which are included in cash flows from financing activities. See Note 17 for additional information regarding our derivative financial instruments.

Unit-based Compensation

Unit-based compensation for our long-term incentive plans is recorded in our consolidated balance sheets based on the fair value of the awards granted and recognized as compensation expense primarily on a straight-line basis over the requisite service period. Forfeitures of our unit-based compensation awards are recognized as an adjustment to compensation expense when they occur. Unit-based compensation expense is included in “General and administrative expenses” on our consolidated statements of income. See Note 24 for additional information regarding our unit-based compensation.

Margin Deposits

Margin deposits relate to our exchange-traded derivative contracts and generally vary based on changes in the value of the contracts. Margin deposits are included in “Other current assets” in the consolidated balance sheets.

Foreign Currency Translation

The functional currencies of our foreign subsidiaries are the local currencies of the countries in which the subsidiaries are located, except for our subsidiaries located in St. Eustatius in the Caribbean Netherlands (formerly the Netherlands Antilles), whose functional currency is the U.S. dollar. The assets and liabilities of our foreign subsidiaries with local functional currencies are translated to U.S. dollars at period-end exchange rates, and income and expense items are translated to U.S. dollars at weighted-average exchange rates in effect during the period. These translation adjustments are included in “Accumulated other comprehensive loss” in the equity section of the consolidated balance sheets. Gains and losses on foreign currency transactions are included in “Other income (expense), net” in the consolidated statements of income.

NEW ACCOUNTING PRONOUNCEMENTS	12 Months Ended
NEW ACCOUNTING PRONOUNCEMENTS	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
NEW ACCOUNTING PRONOUNCEMENTS	NEW ACCOUNTING PRONOUNCEMENTS Securities and Exchange Commission Disclosure Update and Simplification In August 2018, the Securities and Exchange Commission (SEC) issued final rules regarding disclosure requirements that were redundant, duplicative, overlapping or superseded by other SEC requirements or GAAP. The final rules primarily eliminated or reduced certain disclosure requirements, although they also required some additional disclosures. The guidance became effective on November 5, 2018, with an exception for the new disclosure requirement to present changes in partners’ equity in interim periods, which permits entities to begin disclosing this information in the quarter that begins after the effective date of the final rules. We elected to utilize this exception, and will begin presenting statements of partners’ equity on an interim basis beginning with the quarter ending March 31, 2019. These final rules did not have an impact on our financial position or results of operations. Cloud Computing Arrangements In August 2018, the Financial Accounting Standards Board (FASB) issued guidance addressing a customer’s accounting for implementation costs incurred in a cloud computing arrangement (CCA) that is considered a service contract. Under the new guidance, implementation costs for a CCA should be evaluated for capitalization using the same approach as implementation costs associated with internal-use software and expensed over the term of the hosting arrangement. The guidance is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. Prospective adoption for eligible costs incurred on or after the date of adoption or retrospective adoption are permitted. We are currently evaluating whether we will adopt these provisions early and whether we will elect prospective or retrospective adoption, but we do not expect the guidance to have a material impact on our financial position, results of operations or disclosures. Disclosures for Defined Benefit Plans In August 2018, the FASB issued amended guidance that makes minor changes to the disclosure requirements for employers that sponsor defined benefit pension and/or other postretirement benefit plans. The guidance is effective for annual periods beginning after December 15, 2020, with early adoption permitted, using a retrospective approach. We are currently evaluating whether we will adopt these provisions early, but we do not expect the guidance to have a material impact on our financial position, results of operations or disclosures. Unit-Based Payments to Nonemployees In June 2018, the FASB issued amended guidance which aligns the measurement and classification guidance for unit-based payments to nonemployees with the guidance for unit-based payments to employees, with certain exceptions. Under the amended guidance, unit-based payment awards to nonemployees will be measured at their grant date fair value. The guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. The amended guidance should be applied by means of a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. We adopted these provisions on January 1, 2019, and the guidance did not have a material impact on our financial position, results of operations or disclosures. Comprehensive Income In February 2018, the FASB issued amended guidance which provides an entity the option to reclassify stranded tax effects caused by the Tax Cuts and Jobs Act of 2017 (the Act) from accumulated other comprehensive income to retained earnings, and also requires certain additional disclosures about those stranded tax effects. The guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. The new requirements should be applied using one of two transition methods, either at the beginning of the period of adoption or retrospectively. We early adopted these provisions in the fourth quarter of 2018 by electing to reclassify the stranded tax effects caused by the Act from AOCI to common limited partners’ equity as of the beginning of the quarter. The guidance did not have a material impact on our financial position, results of operations or disclosures. Derivatives and Hedging In August 2017, the FASB issued amended guidance intended to improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. The amended guidance also makes certain targeted improvements to simplify the application of current hedge accounting guidance. The guidance is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. Certain of the new requirements should be applied prospectively, while others should be applied using a modified retrospective transition method. We adopted the amended guidance on January 1, 2019, and it did not have a material impact on our financial position, results of operations or disclosures. Defined Benefit Plans In March 2017, the FASB issued amended guidance that changes the presentation of net periodic pension cost related to defined benefit plans. Under the amended guidance, the service cost component of net periodic benefit cost is presented in the same income statement line items as other current employee compensation costs, but the remaining components of net periodic benefit cost are presented outside of operating income. The changes are effective for annual and interim periods beginning after December 15, 2017, and amendments should be applied retrospectively. We began reporting the remaining components of net periodic benefit cost in “Other income, net” in the consolidated statements of comprehensive income upon adoption of the amended guidance on January 1, 2018. We applied the amended guidance prospectively as it did not have a material impact on previous periods. Goodwill In January 2017, the FASB issued amended guidance that simplifies the accounting for goodwill impairment by eliminating step 2 of the goodwill impairment test. Under the amended guidance, goodwill impairment will be measured as the excess of the reporting unit’s carrying value over its fair value, not to exceed the carrying amount of goodwill for that reporting unit. The changes are effective for annual and interim periods beginning after December 15, 2019, and amendments should be applied prospectively. Early adoption is permitted for any impairment tests performed after January 1, 2017, and we are currently evaluating whether we will adopt these provisions early. Regardless of our decision, we do not expect the guidance to have a material impact on our financial position, results of operations or disclosures. Credit Losses In June 2016, the FASB issued amended guidance that requires the use of a “current expected loss” model for financial assets measured at amortized cost and certain off-balance sheet credit exposures. Under this model, entities will be required to estimate the lifetime expected credit losses on such instruments based on historical experience, current conditions, and reasonable and supportable forecasts. This amended guidance also expands the disclosure requirements to enable users of financial statements to understand an entity’s assumptions, models and methods for estimating expected credit losses. The changes are effective for annual and interim periods beginning after December 15, 2019, and amendments should be applied using a modified retrospective approach. We currently expect to adopt the amended guidance on January 1, 2020, and we are assessing the impact of this amended guidance on our financial position, results of operations and disclosures. We plan to provide additional information about the expected impact at a future date. Leases In February 2016, the FASB issued amended guidance that requires lessees to recognize the assets and liabilities that arise from most leases on the balance sheet. For lessors, this amended guidance modifies the classification criteria and the accounting for sales-type and direct financing leases. The changes are effective for annual and interim periods beginning after December 15, 2018, and amendments should be applied using one of two modified retrospective transition methods. We adopted these provisions on January 1, 2019 through a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The transition adjustment related to the adoption was immaterial. We elected the package of practical expedients permitted under the transition guidance within the new standard, which, among other things, allowed us to carry forward historical lease classification. We also elected the practical expedient related to land easements, which allowed us to carry forward our historical accounting treatment for land easements on existing agreements, and the practical expedient to not account for lease and non-lease components separately for most of our asset classes. Right-of-use assets were less than 5% of total assets as of January 1, 2019, and lease liabilities did not significantly differ from right-of-use assets. We do not expect the guidance to have a material impact on our results of operations or cash flows. We intend to provide additional disclosures as required by the new standard, which we are currently assessing, in our quarterly report on Form 10-Q for the first quarter of 2019. Revenue Recognition In May 2014, the FASB and the International Accounting Standards Board jointly issued a comprehensive new revenue recognition standard that requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to in exchange for those goods or services. The standard is effective for public entities for annual and interim periods beginning after December 15, 2017, using one of two retrospective transition methods. We adopted these provisions January 1, 2018 using the modified retrospective approach. The transition adjustment related to the adoption was immaterial. Please refer to Note 6 for further discussion.

MERGER AND RELATED PARTY AGREEMENTS

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

MERGER AND RELATED PARTY TRANSACTIONS

MERGER AND RELATED PARTY AGREEMENTS

On February 7, 2018, NuStar Energy, Riverwalk Logistics, L.P., NuStar GP, LLC, Marshall Merger Sub LLC, a wholly owned subsidiary of NuStar Energy (Merger Sub), Riverwalk Holdings, LLC and NuStar GP Holdings entered into an Agreement and Plan of Merger (the Merger Agreement). Pursuant to the Merger Agreement, Merger Sub merged with and into NuStar GP Holdings with NuStar GP Holdings being the surviving entity (the Merger), such that NuStar Energy became the sole member of NuStar GP Holdings following the Merger on July 20, 2018 (refer to Organizational Structure in Item 1. “Business” for charts depicting our organizational structure at December 31, 2018 and before the Merger). Pursuant to the Merger Agreement and at the effective time of the Merger, NuStar Energy’s partnership agreement was amended and restated to, among other things, (i) cancel the incentive distribution rights held by our general partner, (ii) convert the 2% general partner interest in NuStar Energy held by our general partner into a non-economic management interest and (iii) provide the holders of our common units with voting rights in the election of the members of the board of directors of NuStar GP, LLC, beginning at the annual meeting in 2019.

At the effective time of the Merger, each outstanding NuStar GP Holdings common unit was converted into the right to receive 0.55 of a NuStar Energy common unit and all NuStar GP Holdings common units ceased to be outstanding. No fractional NuStar Energy common units were issued in the Merger; instead, each holder of NuStar GP Holdings’ common units otherwise entitled to receive a fractional NuStar Energy common unit received cash in lieu thereof. As a result of the Merger, we issued approximately 23.6 million NuStar Energy common units and cancelled the 10.2 million NuStar Energy common units owned by subsidiaries of NuStar GP Holdings, resulting in approximately 13.4 million incremental NuStar Energy common units outstanding after the Merger. In addition, we repaid NSH’s debt with borrowings under our revolving credit agreement and incurred transaction costs for aggregate cash consideration of approximately $68.0 million.

Also at the effective time of the Merger, each outstanding award of NuStar GP Holdings restricted units was converted, on the same terms and conditions as were applicable to the awards immediately prior to the Merger, into an award of NuStar Energy restricted units. The number of NuStar Energy restricted units subject to the converted awards was determined pursuant to the 0.55 exchange ratio provided in the Merger Agreement.

Following the completion of the Merger, the NuStar GP, LLC board of directors consists of nine members, currently composed of the six members of the NuStar GP, LLC board of directors prior to the Merger and the three independent directors who served prior to the Merger on NuStar GP Holdings’ board of directors.

We accounted for the Merger as an equity transaction similar to a redemption or induced conversion of preferred stock. The excess of (1) the fair value of the consideration transferred in exchange for the outstanding NSH units over (2) the carrying value of the general partner interest in the Partnership was subtracted from net income available to common unitholders in the calculation of net loss per common unit attributable to the Merger as follows (in thousands of dollars, except unit and per unit data):



Consideration transferred:
Fair value of incremental NS common units issued	$	335,106
NSH debt and assumed net current liabilities	52,075
Transaction costs	15,897
Total consideration	403,078

Carrying value of general partner interest	25,999
Loss to common unitholders attributable to the Merger	$	(377,079	)

For the year ended December 31, 2018:
Basic weighted-average common units outstanding	99,490,495
Loss per common unit attributable to the Merger	$	(3.79	)

Related Party Agreements with NSH

GP Services Agreement. Prior to the Employee Transfer discussed in Note 1, our operations were managed by NuStar GP, LLC under a services agreement effective January 1, 2008 pursuant to which employees of NuStar GP, LLC performed services for our U.S. operations. Employees of NuStar GP, LLC provided services to us and NuStar GP Holdings; therefore, we reimbursed NuStar GP, LLC for all employee costs incurred prior to the Employee Transfer, other than the expenses allocated to NuStar GP Holdings. For the year ended December 31, 2016, we incurred $21.7 million in operating expenses and $10.5 million in general and administrative expenses pertaining to our related party transactions prior to the Employee Transfer. In connection with the Employee Transfer, we entered into an Amended and Restated Services Agreement with NuStar GP, LLC, effective March 1, 2016 (the Amended GP Services Agreement), which provided that we furnish administrative services necessary to conduct the business of NuStar GP Holdings, and NuStar GP Holdings compensated us for these services for an annual fee of $1.0 million, subject to adjustment based on the annual merit increase percentage applicable to our employees for the most recently completed fiscal year and for changes in level of service. We terminated the Amended GP Services Agreement in conjunction with the Merger.

Assignment and Assumption Agreement. Also in connection with the Employee Transfer, we entered into an Assignment and Assumption Agreement with NuStar GP, LLC (the Assignment Agreement). Under the Assignment Agreement, NuStar GP, LLC assigned all of its employee benefit plans, programs, contracts, policies, and various of its other agreements and contracts with certain employees, affiliates and third-party service providers (collectively, the Assigned Programs) to NuStar Services Co. In addition, NuStar Services Co agreed to assume the sponsorship of and all obligations relating to the ongoing maintenance and administration of each of the plans and agreements in the Assigned Programs.

Non-Compete Agreement. On July 19, 2006, we entered into a non-compete agreement with NuStar GP Holdings, Riverwalk Logistics, L.P. and NuStar GP, LLC (the Non-Compete Agreement). The Non-Compete Agreement became effective on December 22, 2006. Under the Non-Compete Agreement, we had the right of first refusal with respect to the potential acquisition of assets related to the transportation, storage or terminalling of crude oil, feedstocks or refined products (including petrochemicals) in the United States and internationally. NuStar GP Holdings had a right of first refusal with respect to the potential acquisition of general partner and other equity interests in publicly traded partnerships under common ownership with the general partner interest. As a result of the Merger, the Non-Compete Agreement was terminated, effective July 20, 2018.

DISPOSITION AND ACQUISITIONS

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

DISPOSITION AND ACQUISITIONS

Disposition

Sale of European Operations. On November 30, 2018, we sold our European operations to Inter Terminals, Ltd. for approximately $270.0 million. The operations sold include six liquids storage terminals in the United Kingdom and one facility in Amsterdam, with total storage capacity of approximately 9.5 million barrels. We sold these non-core assets that were not synergistic with our other operations as part of our plan to significantly improve our debt metrics and partially fund capital projects to grow our core business. We recognized a non-cash loss of $43.4 million related to the sale in “Other income (expense), net” on our consolidated statement of income for the year ended December 31, 2018.

Acquisitions

Council Bluffs Acquisition. On April 16, 2018, we acquired CHS Inc.’s Council Bluffs pipeline system, comprised of a 227-mile pipeline and 18 storage tanks, for approximately $37.5 million. The assets acquired and the results of operations are included in our pipeline segment from the date of acquisition. We accounted for this acquisition as an asset purchase.

Navigator Acquisition. On April 11, 2017, we entered into a Membership Interest Purchase and Sale Agreement (the Acquisition Agreement) with FR Navigator Holdings LLC to acquire (the Navigator Acquisition) all of the issued and outstanding limited liability company interests in Navigator Energy Services, LLC (Navigator) for approximately $1.5 billion. We closed the Navigator Acquisition on May 4, 2017. We acquired crude oil transportation, pipeline connection and storage assets located in the Midland Basin in West Texas that, together with the assets we have constructed through various expansion projects since the date of the Navigator Acquisition, we collectively refer to as our Permian Crude System. The assets acquired are included in our pipeline segment. The consolidated statements of income include the results of operations for Navigator commencing on May 4, 2017.

We accounted for the Navigator Acquisition using the acquisition method. The following table reflects the final purchase price allocation:



	Purchase Price Allocation
	(Thousands of Dollars)
Accounts receivable	$	4,747
Other current assets	2,359
Property, plant and equipment, net	376,690
Intangible assets (a)	700,000
Goodwill (b)	398,024
Other long-term assets, net	2,199
Current liabilities	(22,300		)
Purchase price allocation, net of cash acquired	$	1,461,719


(a)	Intangible assets, which consist of customer contracts and relationships, are amortized on a straight-line basis over a period of 20 years.


(b)	The goodwill acquired represents the expected benefit from entering new geographic areas and the anticipated opportunities to generate future cash flows from the assets acquired and potential future projects.

The unaudited pro forma information for the years ended December 31, 2017 and 2016 below presents the combined historical financial information for Navigator and the Partnership for those periods. This information assumes:


•	we completed the Navigator Acquisition on January 1, 2016;


•	we issued approximately 14.4 million common units;


•	we received a contribution from our general partner of $13.6 million to maintain the 2% general partner economic interest it owned at that time;


•	we issued 15.4 million Series B Preferred Units;


•	we issued $550.0 million of 5.625% senior notes;


•	additional depreciation and amortization that would have been incurred assuming the fair value adjustments to property, plant and equipment and intangible assets reflected in the purchase price allocation above; and


•	we satisfied Navigator’s outstanding obligations under its revolving credit agreement.



	Year Ended December 31,
	2017		2016
	(Thousands of Dollars, Except Per Unit Data)
Revenues	$	1,828,418	$	1,782,932
Net income	$	127,433	$	78,664

Basic and diluted net income per common unit	$	0.31	$	0.01

The pro forma information for the year ended December 31, 2017 includes transaction costs of $14.1 million, which were directly attributable to the Navigator Acquisition. The pro forma information is unaudited and is not necessarily indicative of the results of operations that would have resulted had the Navigator Acquisition occurred on January 1, 2016 or that may result in the future.

Martin Terminal Acquisition. On December 21, 2016, we acquired crude oil and refined product storage assets in Corpus Christi, TX for $95.7 million, including $2.1 million of capital expenditure reimbursements, from Martin Operating Partnership L.P. (the Martin Terminal Acquisition). The assets acquired are in our storage segment and include 900,000 barrels of crude oil storage capacity, 250,000 barrels of refined product storage capacity and exclusive use of the Port of Corpus Christi’s new crude oil dock.

REVENUE FROM CONTRACTS WITH CUSTOMERS

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Revenue from Contracts with Customers

REVENUE FROM CONTRACTS WITH CUSTOMERS

Transition

On January 1, 2018, we adopted ASC Topic 606 using the modified retrospective method and applied ASC Topic 606 to all revenue contracts with customers. Results for reporting periods beginning after January 1, 2018 are presented under ASC Topic 606. In accordance with the modified retrospective approach, prior period amounts were not adjusted and are reported under ASC Topic 605, “Revenue Recognition.” The adoption of ASC Topic 606 affected our consolidated statements of comprehensive income as follows:



	As Reported			Without Adoption of ASC Topic 606			Effect of Change Higher/(Lower)
	(Thousands of Dollars, Except Per Unit Data)
For the year ended December 31, 2018:
Revenues	$	1,961,757		$	1,967,942		$	(6,185	)
Operating income	$	363,563		$	369,748		$	(6,185	)
Net income	$	205,794		$	211,979		$	(6,185	)
Basic net loss per common unit	$	(2.77	)	$	(2.70	)	$	(0.07	)

Contract Assets and Liabilities

The following table provides information about contract assets and contract liabilities from contracts with customers:



	Contract Assets			Contract Liabilities
	(Thousands of Dollars)
Balance as of January 1, 2018	$	2,127		$	(60,464	)

Additions	3,281			(83,243		)
Transfer to accounts receivable	(2,803		)	—
Transfer to revenues	—			57,826
Total activity	478			(25,417		)


Balance as of December 31, 2018	2,605			(85,881		)
Less current portion	2,066			(46,936		)
Noncurrent portion	$	539		$	(38,945	)

Contract assets relate to performance obligations satisfied in advance of scheduled billings. Current contract assets are included in “Other current assets” and noncurrent contract assets are included in “Other long-term assets, net” on the consolidated balance sheet. Contract liabilities relate to payments received in advance of satisfying performance obligations under a contract, which mainly result from contracts with MVCs, contracts with an incentive pricing structure and CIAC payments. Current contract liabilities are included in “Accrued liabilities” and noncurrent contract liabilities are included in “Other long-term liabilities” on the consolidated balance sheet.

In the third quarter of 2018, we entered into an agreement whereby our customer transferred ownership of crude oil to us, and we agreed to sell the crude oil and apply the proceeds as a non-refundable, one-time payment of storage fees. At the time of the agreement, we recognized a contract liability of $37.5 million.

In the second quarter of 2018, one customer for whom we had recorded a contract liability to perform future services elected not to extend the term of its terminal storage contract, thus reducing our future performance obligation. As a result, we adjusted the related contract liability and recognized $9.0 million in revenue.

Remaining Performance Obligations

The following table presents our estimated revenue from contracts with customers for remaining performance obligations that has not yet been recognized, representing our contractually committed revenue as of December 31, 2018 (in thousands of dollars):



2019	$	473,027
2020	383,889
2021	261,900
2022	210,772
2023	162,952
Thereafter	361,153
Total	$	1,853,693

Our contractually committed revenue, for purposes of the tabular presentation above, is generally limited to customer contracts that have fixed pricing and fixed volume terms and conditions, generally including contracts with MVC payment obligations.

Disaggregation of Revenues

The following table disaggregates our revenues:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Pipeline segment:
Crude oil pipelines (excluding lessor revenues)	$	248,261		$	187,874		$	154,543
Refined products and ammonia pipelines	362,750			328,414			331,107
Total pipeline segment revenues from contracts with customers	611,011			516,288			485,650
Lessor revenues	54			—			—
Total pipeline segment revenues	611,065			516,288			485,650

Storage segment:
Throughput terminals	83,157			85,927			117,586
Storage terminals (excluding lessor revenues)	482,944			491,900			492,456
Total storage segment revenues from contracts with customers	566,101			577,827			610,042
Lessor revenues	39,849			39,126			—
Total storage segment revenues	605,950			616,953			610,042

Fuels marketing segment revenues from contracts with customers	752,312			692,884			681,934

Consolidation and intersegment eliminations	(7,570		)	(12,106		)	(20,944		)

Total revenues	$	1,961,757		$	1,814,019		$	1,756,682

ALLOWANCE FOR DOUBTFUL ACCOUNTS

12 Months Ended

Dec. 31, 2018

Accounts Receivable Additional Disclosures [Abstract]

ALLOWANCE FOR DOUBTFUL ACCOUNTS

The changes in the allowance for doubtful accounts consisted of the following:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Balance as of beginning of year	$	9,948		$	7,756		$	8,473
Increase in allowance, net	755			2,217			24
Accounts charged against the allowance	(1,291		)	(25		)	(741		)
Balance as of end of year	$	9,412		$	9,948		$	7,756

INVENTORIES

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

INVENTORIES

Inventories consisted of the following:



	December 31,
	2018		2017
	(Thousands of Dollars)
Petroleum products	$	12,689	$	17,027
Materials and supplies	10,024		9,830
Total	$	22,713	$	26,857

We purchase petroleum products for resale. Our petroleum products consist of intermediates, gasoline, distillates and other petroleum products. Materials and supplies mainly consist of blending and additive chemicals and maintenance materials used in our pipeline and storage segments.

PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consisted of the following:



	Estimated Useful Lives			December 31,
	Estimated Useful Lives			2018			2017
	(Years)			(Thousands of Dollars)
Land		-		$	143,477		$	143,527
Land and leasehold improvements	5	-	40	215,796			203,085
Buildings	15	-	40	160,069			151,702
Pipelines, storage and terminals	15	-	40	5,315,201			5,080,795
Rights-of-way	20	-	40	301,739			264,170
Construction in progress		-		202,030			400,202
Total				6,338,312			6,243,481
Less accumulated depreciation and amortization				(2,049,690		)	(1,942,548		)
Property, plant and equipment, net				$	4,288,622		$	4,300,933

Capitalized interest costs added to property, plant and equipment totaled $7.8 million, $5.5 million and $3.4 million for the years ended December 31, 2018, 2017 and 2016, respectively. Depreciation and amortization expense for property, plant and equipment totaled $243.5 million, $222.5 million and $200.7 million for the years ended December 31, 2018, 2017 and 2016, respectively.

INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2018

Intangible Assets, Net (Excluding Goodwill) [Abstract]

INTANGIBLE ASSETS

Intangible assets consisted of the following:



		December 31, 2018					December 31, 2017
	Weighted-Average Amortization Period	Cost		Accumulated Amortization			Cost		Accumulated Amortization
	(Years)	(Thousands of Dollars)
Customer contracts and relationships	18	$	863,950	$	(132,509	)	$	863,950	$	(81,136	)
Other	47	2,359		(744		)	2,359		(694		)
Total		$	866,309	$	(133,253	)	$	866,309	$	(81,830	)

Intangible assets are recorded at fair value as of the date acquired. All of our intangible assets are amortized on a straight-line basis. Amortization expense for intangible assets was $51.4 million, $39.6 million and $13.9 million for the years ended December 31, 2018, 2017 and 2016, respectively. The estimated aggregate amortization expense is approximately $51.0 million for each of the years 2019 through 2022, and approximately $45.0 million for 2023.

GOODWILL

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL

Changes in the carrying amount of goodwill by segment were as follows:



	Pipeline			Storage			Fuels Marketing		Total
	(Thousands of Dollars)
Balances as of January 1, 2017:
Goodwill	$	306,207		$	663,760		$	31,123	$	1,001,090
Accumulated impairment losses	—			(304,453		)	—		(304,453		)
Net goodwill	306,207			359,307			31,123		696,637

Activity for the year ended December 31, 2017:
Navigator Acquisition preliminary purchase price allocation (a)	400,838			—			—		400,838

Balances as of December 31, 2017:
Goodwill	707,045			663,760			31,123		1,401,928
Accumulated impairment losses	—			(304,453		)	—		(304,453		)
Net goodwill	707,045			359,307			31,123		1,097,475

Activity for the year ended December 31, 2018:
Navigator Acquisition purchase price allocation adjustments (a)	(2,814		)	—			—		(2,814		)
Adjustment due to the sale of our European operations (a)	—			(57,685		)	—		(57,685		)

Balances as of December 31, 2018:
Goodwill	704,231			606,075			31,123		1,341,429
Accumulated impairment losses	—			(304,453		)	—		(304,453		)
Net goodwill	$	704,231		$	301,622		$	31,123	$	1,036,976


(a)	See Note 5 for discussion of the Navigator Acquisition and the sale of our European operations.

ACCRUED LIABILITIES

12 Months Ended

Dec. 31, 2018

Accrued Liabilities, Current [Abstract]

ACCRUED LIABILITIES

Accrued liabilities consisted of the following:



	December 31,
	2018		2017
	(Thousands of Dollars)
Employee wages and benefit costs	$	30,720	$	16,963
Revenue contract liabilities	46,936		—
Deferred revenue	—		18,243
Other	24,337		26,372
Accrued liabilities	$	101,993	$	61,578

DEBT

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

DEBT

Long-term debt consisted of the following:



				December 31,
	Maturity			2018			2017
				(Thousands of Dollars)
Revolving Credit Agreement		2020		$	745,000		$	893,311
7.65% senior notes		2018		—			350,000
4.80% senior notes		2020		450,000			450,000
6.75% senior notes		2021		300,000			300,000
4.75% senior notes		2022		250,000			250,000
5.625% senior notes		2027		550,000			550,000
Subordinated Notes		2043		402,500			402,500
GoZone Bonds	2038	thru	2041	365,440			365,440
Receivables Financing Agreement		2020		61,800			62,300
Net fair value adjustments, unamortized discounts and unamortized debt issuance costs		N/A		(12,744		)	(10,492		)
Total long-term debt				3,111,996			3,613,059
Less current portion				—			349,990
Long-term debt, less current portion				$	3,111,996		$	3,263,069

The long-term debt repayments are due as follows (in thousands of dollars):



2019	$	—
2020	1,256,800
2021	300,000
2022	250,000
2023	—
Thereafter	1,317,940
Total repayments	3,124,740
Net fair value adjustments, unamortized discounts and unamortized debt issuance costs	(12,744		)
Total long-term debt	$	3,111,996

Interest payments totaled $190.9 million, $163.6 million and $146.1 million for the years ended December 31, 2018, 2017 and 2016, respectively. We amortized an aggregate of $7.1 million, $5.0 million and $4.4 million of debt issuance costs and debt discount for the years ended December 31, 2018, 2017 and 2016, respectively.

Revolving Credit Agreement

On June 29, 2018, NuStar Logistics amended its revolving credit agreement (the Revolving Credit Agreement) to exclude the Series D Preferred Units from the definition of “Indebtedness.” Additionally, the amendment reduced the total amount available for borrowing from $1.75 billion to $1.575 billion, effective June 29, 2018, with a further reduction to $1.4 billion, effective December 28, 2018. The Revolving Credit Agreement was also amended to, among other things, add a minimum consolidated interest coverage ratio (as defined in the Revolving Credit Agreement), which must not be less than 1.75-to-1.00 for each rolling period of four quarters, beginning with the rolling period ending June 30, 2018.

On March 28, 2018, NuStar Logistics amended the Revolving Credit Agreement to increase the maximum allowed consolidated debt coverage ratio (as defined in the Revolving Credit Agreement) to 5.25-to-1.00 for the rolling periods ending June 30, 2018 through December 31, 2018. For any rolling periods ending on or after March 31, 2019, the maximum allowed consolidated debt coverage ratio may not exceed 5.00-to-1.00. If we complete one or more acquisitions for aggregate net consideration of at least $50.0 million, our maximum consolidated debt coverage ratio will increase to 5.50-to-1.00 for two rolling periods. The Revolving Credit Agreement was also amended to, among other things, provide that the definition of “Change in Control” in the Revolving Credit Agreement excludes the Merger discussed in Note 4.

The maximum consolidated debt coverage ratio and minimum consolidated interest coverage ratio requirements may limit the amount we can borrow under the Revolving Credit Agreement to an amount less than the total amount available for borrowing. The Revolving Credit Agreement also contains customary restrictive covenants, such as limitations on indebtedness, liens, mergers, asset transfers and certain investing activities. As of December 31, 2018, we believe that we are in compliance with the covenants in the Revolving Credit Agreement.

As of December 31, 2018, we had $651.3 million available for borrowing. The Revolving Credit Agreement includes the ability to borrow up to the equivalent of $250.0 million in Euros and up to the equivalent of $250.0 million in British Pounds Sterling. Obligations under the Revolving Credit Agreement are guaranteed by NuStar Energy and NuPOP. For the year ended December 31, 2018, we recorded deferred issuance costs of $4.0 million associated with the Revolving Credit Agreement to “Other long-term assets, net” on the consolidated balance sheet.

The Revolving Credit Agreement bears interest, at our option, based on an alternative base rate, a LIBOR-based rate or a EURIBOR-based rate. The interest rate on the Revolving Credit Agreement is subject to adjustment if our debt rating is downgraded (or upgraded) by certain credit rating agencies. In February 2018, Moody’s Investor Service Inc. (Moody’s) lowered our credit rating from Ba1 to Ba2. This rating downgrade caused the interest rate on our Revolving Credit Agreement to increase by 0.25% effective February 2018. As of December 31, 2018, our weighted-average interest rate was 4.5%, and we had $745.0 million outstanding. During the year ended December 31, 2018, the weighted-average interest rate related to borrowings under the Revolving Credit Agreement was 4.1%.

Letters of credit issued under the Revolving Credit Agreement totaled $3.7 million as of December 31, 2018. Letters of credit are limited to $400.0 million (including up to the equivalent of $25.0 million in Euros and up to the equivalent of $25.0 million in British Pounds Sterling) and also may restrict the amount we can borrow under the Revolving Credit Agreement.

Notes

NuStar Logistics Senior Notes. On April 28, 2017, NuStar Logistics issued $550.0 million of 5.625% senior notes due April 28, 2027. We used the net proceeds of $543.3 million from the offering to fund a portion of the purchase price for the Navigator Acquisition and to pay related fees and expenses. The interest on the 5.625% senior notes is payable semi-annually in arrears on April 28 and October 28 of each year beginning on October 28, 2017.

Interest is payable semi-annually in arrears for the $450.0 million of 4.80% senior notes, $300.0 million of 6.75% senior notes, $250.0 million of 4.75% senior notes and $550.0 million of 5.625% senior notes (collectively, the NuStar Logistics Senior Notes). The credit rating downgrade by Moody’s in February 2018 increased the interest rate on our $350.0 million of 7.65% senior notes by 0.25%, resulting in an interest rate of 8.65% applicable to the interest payment due April 15, 2018. We repaid these notes on April 15, 2018 with borrowings under our Revolving Credit Agreement.

The NuStar Logistics Senior Notes do not have sinking fund requirements. These notes rank equally with existing senior unsecured indebtedness and senior to existing subordinated indebtedness of NuStar Logistics and contain restrictions on NuStar Logistics’ ability to incur additional secured indebtedness unless the same security is also provided for the benefit of holders of the NuStar Logistics Senior Notes. In addition, the NuStar Logistics Senior Notes limit NuStar Logistics’ ability to incur indebtedness secured by certain liens and to engage in certain sale-leaseback transactions. At the option of NuStar Logistics, the NuStar Logistics Senior Notes may be redeemed in whole or in part at any time at a redemption price, which includes a make-whole premium, plus accrued and unpaid interest to the redemption date. If we undergo a change of control, as defined in the supplemental indentures for the 6.75% senior notes or the 5.625% senior notes, each holder of the 6.75% senior notes or the 5.625% senior notes may require us to repurchase all or a portion of its notes at a price equal to 101% of the principal amount of the notes, plus any accrued and unpaid interest to the date of repurchase. The NuStar Logistics Senior Notes are fully and unconditionally guaranteed by NuStar Energy and NuPOP.

NuStar Logistics Subordinated Notes. NuStar Logistics’ $402.5 million of fixed-to-floating rate subordinated notes are due January 15, 2043 (the Subordinated Notes). The Subordinated Notes are fully and unconditionally guaranteed on an unsecured and subordinated basis by NuStar Energy and NuPOP. Effective January 15, 2018, the interest rate on the Subordinated Notes switched from a fixed annual rate of 7.625%, payable quarterly in arrears, to an annual rate equal to the sum of the three-month LIBOR for the related quarterly interest period, plus 6.734% payable quarterly, commencing April 15, 2018, unless payment is deferred in accordance with the terms of the notes. NuStar Logistics may elect to defer interest payments on the Subordinated Notes on one or more occasions for up to five consecutive years. Deferred interest will accumulate additional interest at a rate equal to the interest rate then applicable to the Subordinated Notes until paid. If NuStar Logistics elects to defer interest payments, NuStar Energy cannot declare or make cash distributions to its unitholders during the period that interest payments are deferred. As of December 31, 2018, the interest rate was 9.2%.

The Subordinated Notes do not have sinking fund requirements and are subordinated to existing senior unsecured indebtedness of NuStar Logistics and NuPOP. The Subordinated Notes do not contain restrictions on NuStar Logistics’ ability to incur additional indebtedness, including debt that ranks senior in priority of payment to the notes. In addition, the Subordinated Notes do not limit NuStar Logistics’ ability to incur indebtedness secured by liens or to engage in certain sale-leaseback transactions. Effective January 15, 2018, we may redeem the Subordinated Notes in whole or in part at a redemption price equal to 100% of the principal amount plus accrued and unpaid interest to the redemption date.

Gulf Opportunity Zone Revenue Bonds

In 2008, 2010 and 2011, the Parish of St. James, Louisiana issued Revenue Bonds Series 2008, Series 2010, Series 2010A, Series 2010B and Series 2011 associated with our St. James terminal expansions pursuant to the Gulf Opportunity Zone Act of 2005 for an aggregate $365.4 million (collectively, the GoZone Bonds). The interest rates on these bonds are based on a weekly tax-exempt bond market interest rate, and interest is paid monthly. Following the issuances, the proceeds were deposited with a trustee and are disbursed to us upon our request for reimbursement of expenditures related to our St. James terminal expansions. We include the amount remaining in the trust in “Other long-term assets, net,” and we include the amount of bonds issued in “Long-term debt” in our consolidated balance sheets. We did not receive any proceeds from the trustee for the years ended December 31, 2018 and 2017.

NuStar Logistics is solely obligated to service the principal and interest payments associated with the GoZone Bonds. Letters of credit were issued by various individual banks on our behalf to guarantee the payment of interest and principal on the bonds. All letters of credit rank equally with existing senior unsecured indebtedness of NuStar Logistics and generally contain the same restrictive covenants, maximum consolidated debt coverage ratio and minimum consolidated interest coverage ratio requirements as the Revolving Credit Agreement. Obligations under the letters of credit issued are guaranteed by NuStar Energy and NuPOP. The letters of credit issued by individual banks do not restrict the amount we can borrow under the Revolving Credit Agreement.

The following table summarizes the GoZone Bonds outstanding as of December 31, 2018:



Date Issued	Maturity Date	Amount Outstanding		Amount of Letter of Credit		Amount Received from Trustee		Amount Remaining in Trust (a)		Interest Rate (b)
		(Thousands of Dollars)
June 26, 2008	June 1, 2038	$	55,440	$	56,169	$	55,440	$	—	1.8	%
July 15, 2010	July 1, 2040	100,000		101,315		100,000		—		1.8	%
October 7, 2010	October 1, 2040	50,000		50,658		43,741		6,596		1.8	%
December 29, 2010	December 1, 2040	85,000		86,118		49,782		36,271		1.8	%
August 29, 2011	August 1, 2041	75,000		75,986		75,000		—		1.8	%
	Total	$	365,440	$	370,246	$	323,963	$	42,867


(a)	Amount remaining in trust includes accrued interest.


(b)	For the year ended December 31, 2018, our weighted-average interest rate on borrowings was 1.4%.

Receivables Financing Agreement

NuStar Energy and NuStar Finance LLC (NuStar Finance), a special purpose entity and wholly owned subsidiary of NuStar Logistics, are parties to a $125.0 million receivables financing agreement with third-party lenders (the Receivables Financing Agreement) and agreements with certain of NuStar Energy’s wholly owned subsidiaries (collectively with the Receivables Financing Agreement, the Securitization Program). Under the Securitization Program, certain of NuStar Energy’s wholly owned subsidiaries (collectively, the Originators), sell their accounts receivable to NuStar Finance on an ongoing basis, and NuStar Finance provides the newly acquired accounts receivable as collateral for its revolving borrowings under the Receivables Financing Agreement. NuStar Energy provides a performance guarantee in connection with the Securitization Program. The March 28, 2018 amendment to the Revolving Credit Agreement also limits the amount of borrowings by NuStar Finance under the Receivables Financing Agreement to $125.0 million. The amount available for borrowing is based on the availability of eligible receivables and other customary factors and conditions. The Securitization Program contains various customary affirmative and negative covenants and default, indemnification and termination provisions, and the Receivables Financing Agreement provides for acceleration of amounts owed upon the occurrence of certain specified events. NuStar Finance’s sole activity consists of purchasing such receivables and providing them as collateral under the Securitization Program. NuStar Finance is a separate legal entity and the assets of NuStar Finance, including these accounts receivable, are not available to satisfy the claims of creditors of NuStar Energy, the Originators or their affiliates.

On March 28, 2018, the Receivables Financing Agreement was amended to change the definition of Change in Control in the Receivables Financing Agreement such that the Merger discussed in Note 4 would not be a Change in Control for purposes of the Receivables Financing Agreement. On September 20, 2017, the Securitization Program was amended to add certain of NuStar Energy’s wholly owned subsidiaries resulting from the Navigator Acquisition and to extend the Securitization Program’s scheduled termination date from June 15, 2018 to September 20, 2020, with the option to renew for additional 364-day periods thereafter. Borrowings by NuStar Finance under the Receivables Financing Agreement bear interest at the applicable bank rate, as defined under the Receivables Financing Agreement. As of December 31, 2018 and 2017, accounts receivable totaling $95.5 million and $92.6 million, respectively, were included in the Securitization Program. The weighted average interest rate related to outstanding borrowings under the Securitization Program during the year ended December 31, 2018 was 3.0%.

Short-Term Line of Credit

NuStar Logistics is party to a short-term line of credit agreement with an uncommitted borrowing capacity of up to $35.0 million, which allows us to better manage fluctuations in our daily cash requirements and minimize our excess cash balances. The interest rates and maturities vary and are determined at the time of borrowing. We had $18.5 million outstanding under this line of credit as of December 31, 2018. Obligations under this short-term line of credit agreement are guaranteed by NuStar Energy. As of December 31, 2018 and 2017, the weighted-average interest rates related to outstanding borrowings under our short-term line of credit were 4.4% and 3.2%, respectively.

HEALTH, SAFETY AND ENVIRONMENTAL MATTERS

12 Months Ended

Dec. 31, 2018

Environmental Remediation Obligations [Abstract]

HEALTH, SAFETY AND ENVIRONMENTAL MATTERS

Our operations are subject to extensive international, federal, state and local environmental laws and regulations, in the U.S. and in the other countries in which we operate, including those relating to the discharge of materials into the environment, waste management, remediation, the characteristics and composition of fuels, climate change and greenhouse gases. Our operations are also subject to extensive health, safety and security laws and regulations, including those relating to worker and pipeline safety, pipeline and storage tank integrity and operations security. The principal environmental, health, safety and security risks associated with our operations relate to unauthorized emissions into the air, releases into soil, surface water or groundwater, personal injury and property damage. We have adopted policies, practices, systems and procedures to comply with the laws and regulations, mitigate these risks, limit the liability that could result from such events, prevent material environmental or other damage, ensure the safety of our employees and the public and secure our pipelines, terminals and operations. Compliance with environmental, health, safety and security laws, regulations and related permits increases our capital expenditures and operating expenses, and violation of these laws, regulations or permits could result in significant civil and criminal liabilities, injunctions or other penalties. Future governmental action and regulatory initiatives could necessitate changes to expected operating permits and procedures, additional remedial actions or increased capital expenditures and operating costs. Risks of additional costs and liabilities are inherent within the industry, and there can be no assurances that significant costs and liabilities will not be incurred in the future.

Most of our pipelines are subject to federal regulation by one or more of the following governmental agencies: The Federal Energy Regulatory Commission (the FERC), the Surface Transportation Board (the STB), the Department of Transportation (DOT), the Environmental Protection Agency (EPA) and the Department of Homeland Security. Additionally, the operations and integrity of the pipelines are subject to the respective state jurisdictions along the routes of the systems.

Environmental and safety exposures and liabilities are difficult to assess and estimate due to unknown factors such as the timing and extent of remediation, the determination of our liability in proportion to other parties, improvements in cleanup technologies and the extent to which environmental and safety laws and regulations may change in the future. Although environmental and safety costs may have a significant impact on the results of operations for any single period, we believe that such costs will not have a material adverse effect on our financial position.

The balance of and changes in the accruals for environmental matters were as follows:



	Year Ended December 31,
	2018			2017
	(Thousands of Dollars)
Balance as of the beginning of year	$	5,683		$	5,120
Additions to accrual	5,160			3,186
Payments	(3,058		)	(2,675		)
Foreign currency translation	(32		)	52
Balance as of the end of year	$	7,753		$	5,683

Accruals for environmental matters are included in the consolidated balance sheets as follows:



	December 31,
	2018		2017
	(Thousands of Dollars)
Accrued liabilities	$	4,349	$	3,054
Other long-term liabilities	3,404		2,629
Accruals for environmental matters	$	7,753	$	5,683

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Contingencies

We have contingent liabilities resulting from various litigation, claims and commitments. We record accruals for loss contingencies when losses are considered probable and can be reasonably estimated. Legal fees associated with defending the Partnership in legal matters are expensed as incurred. We accrued $2.8 million and $7.3 million for contingent losses as of December 31, 2018 and 2017, respectively. The amount that will ultimately be paid related to such matters may differ from the recorded accruals, and the timing of such payments is uncertain. We evaluate each contingent loss at least quarterly, and more frequently as each matter progresses and develops over time, and we do not believe that the resolution of any particular claim or proceeding, or all matters in the aggregate, would have a material adverse effect on our results of operations, financial position or liquidity.

Commitments

Lessee and Other Commitments. Future minimum rental payments applicable to all noncancellable operating leases and purchase obligations as of December 31, 2018 are as follows:



	Payments Due by Period
	2019		2020		2021		2022		2023		There- after		Total
	(Thousands of Dollars)
Operating leases	$	34,900	$	20,787	$	14,904	$	9,280	$	6,870	$	28,552	$	115,293
Purchase obligations	$	10,896	$	7,958	$	7,011	$	4,970	$	602	$	2,624	$	34,061

Rental expense for operating leases totaled $42.9 million, $36.2 million and $37.0 million for the years ended December 31, 2018, 2017 and 2016, respectively. Our operating leases consist primarily of the following:


•	two leases for tugs and barges utilized at our St. Eustatius facility for bunker fuel sales, with original terms of nine and ten years; and


•	land and dock leases at various terminal facilities, with original terms generally ranging from 5 to 40 years, including a build-to-suit lease with an initial term of five years and four additional five-year renewal periods that also includes a commitment for minimum dockage and wharfage throughput volumes.

Our purchase obligations primarily consist of an eleven-year chemical supply agreement related to our pipelines.

Lessor Revenues. We have entered into certain revenue arrangements where we are considered to be the lessor in accordance with GAAP. Under these arrangements, we lease certain of our storage tanks in exchange for a fixed fee, subject to an annual consumer price index adjustment. The arrangements commenced on January 1, 2017, and have initial terms of ten years with successive ten-year automatic renewal terms. We recognized $39.8 million of lease revenues from these leases for the year ended December 31, 2018, which is included in “Service revenues” in the consolidated statements of income. Future minimum revenues we expect to receive under these lease arrangements as of December 31, 2018 total $313.1 million, which we will recognize ratably over the following eight years. As of December 31, 2018, the cost and accumulated depreciation of leased storage assets totaled $233.2 million and $113.1 million, respectively.

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

We segregate the inputs used in measuring fair value into three levels: Level 1, defined as observable inputs such as quoted prices for identical assets or liabilities in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in markets that are not active; and Level 3, defined as unobservable inputs for which little or no market data exists. We consider counterparty credit risk and our own credit risk in the determination of all estimated fair values.

Recurring Fair Value Measurements

The following assets and liabilities are measured at fair value on a recurring basis:



	December 31, 2018
	Level 1		Level 2			Level 3		Total
	(Thousands of Dollars)
Assets:
Other current assets:
Commodity derivatives	$	130	$	—		$	—	$	130
Other long-term assets, net:
Interest rate swaps	—		627			—		627
Total assets	$	130	$	627		$	—	$	757
Liabilities:
Other long-term liabilities:
Interest rate swaps	$	—	$	(751	)	$	—	$	(751	)



	December 31, 2017
	Level 1			Level 2			Level 3		Total
	(Thousands of Dollars)
Assets:
Other current assets:
Product imbalances	$	3,890		$	—		$	—	$	3,890
Liabilities:
Accrued liabilities:
Product imbalances	$	(1,534	)	$	—		$	—	$	(1,534	)
Commodity derivatives	(878		)	—			—		(878		)
Interest rate swaps	—			(5,394		)	—		(5,394		)
Other long-term liabilities:
Interest rate swaps	—			(4,594		)	—		(4,594		)
Total liabilities	$	(2,412	)	$	(9,988	)	$	—	$	(12,400	)

Product Imbalances. Pursuant to the new revenue recognition standard we adopted January 1, 2018, we no longer recognize the fair value of product imbalances on our consolidated balance sheets. Prior to adoption, we valued our assets and liabilities related to product imbalances using quoted market prices in active markets as of the reporting date; accordingly, we included these product imbalances in Level 1 of the fair value hierarchy.

Commodity Derivatives. We base the fair value of certain of our commodity derivative instruments on quoted prices on an exchange; accordingly, we include these items in Level 1 of the fair value hierarchy. See Note 17 for a discussion of our derivative instruments.

Interest Rate Swaps. Because we estimate the fair value of our forward-starting interest rate swaps using discounted cash flows, which use observable inputs such as time to maturity and market interest rates, we include these interest rate swaps in Level 2 of the fair value hierarchy.

Fair Value of Financial Instruments

We recognize cash equivalents, receivables, payables and debt in our consolidated balance sheets at their carrying amounts. The fair values of these financial instruments, except for long-term debt, approximate their carrying amounts. The estimated fair values and carrying amounts of the long-term debt, including the current portion, were as follows:



	December 31, 2018		December 31, 2017
	(Thousands of Dollars)
Fair value	$	3,056,704	$	3,677,622
Carrying amount	$	3,111,996	$	3,613,059

We have estimated the fair value of our publicly traded notes based upon quoted prices in active markets; therefore, we determined that the fair value of our publicly traded senior notes falls in Level 1 of the fair value hierarchy. With regard to our other debt, for which a quoted market price is not available, we have estimated the fair value using a discounted cash flow analysis using current incremental borrowing rates for similar types of borrowing arrangements and determined that the fair value falls in Level 2 of the fair value hierarchy.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES

12 Months Ended

Dec. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES

We utilize various derivative instruments to manage our exposure to interest rate risk and commodity price risk. Our risk management policies and procedures are designed to monitor interest rates, futures and swap positions and over-the-counter positions, as well as physical volumes, grades, locations and delivery schedules, to help ensure that our hedging activities address our market risks.

Interest Rate Risk

We are a party to certain interest rate swap agreements to manage our exposure to changes in interest rates, which include forward-starting interest rate swap agreements related to a forecasted debt issuance in 2020. We entered into these swaps during the year ended December 31, 2015 in order to hedge the risk of fluctuations in the required interest payments attributable to changes in the benchmark interest rate during the period from the effective date of the swap to the issuance of the forecasted debt. Under the terms of the swaps, we pay a fixed rate and receive a rate based on the three-month USD LIBOR. These swaps qualify as cash flow hedges, and we designate them as such. We record the effective portion of mark-to-market adjustments as a component of AOCI, and the amount in AOCI will be recognized in “Interest expense, net” as the forecasted interest payments occur or if the interest payments are probable not to occur. As of December 31, 2018 and 2017, the aggregate notional amount of forward-starting interest rate swaps totaled $250.0 million and $600.0 million, respectively. In April 2018, in connection with the maturity of the 7.65% senior notes due April 15, 2018, we terminated forward-starting interest rate swaps with an aggregate notional amount of $350.0 million and received $8.0 million. The termination payments are included in cash flows from financing activities on the consolidated statements of cash flows. During the third and fourth quarters of 2018, we determined that two forecasted interest payments were probable not to occur, and we reclassified $0.4 million from AOCI to “Interest expense, net.”

The remaining fair value amount associated with unwound fixed-to-floating interest rate swap agreements totaled $10.5 million and $15.6 million as of December 31, 2018 and 2017, respectively; these assets are included in “Long-term debt” on the consolidated balance sheets. The remaining fair value amount associated with unwound forward-starting interest rate swap agreements totaled $0.8 million and $14.3 million as of December 31, 2018 and 2017, respectively; these losses are included in AOCI on the consolidated balance sheets. These amounts are amortized ratably over the remaining life of the related debt instrument into “Interest expense, net” on the consolidated statements of income.

Commodity Price Risk

We are exposed to market risks related to the volatility of petroleum product prices. In order to reduce the risk of commodity price fluctuations with respect to our petroleum product inventories and related firm commitments to purchase and/or sell such inventories, we utilize commodity futures and swap contracts, which qualify, and we designate, as fair value hedges. Derivatives that are intended to hedge our commodity price risk but fail to qualify as fair value hedges are considered economic hedges, and we record associated gains and losses in net income. Our risk management committee oversees our trading controls and procedures and certain aspects of commodity and trading risk management. Our risk management committee also reviews all new commodity and trading risk management strategies in accordance with our risk management policy, as approved by our board of directors. We ceased marketing crude oil in the second quarter of 2017 and exited our heavy fuels trading operations in the third quarter of 2017, thereby reducing our overall hedging activity.

The volume of commodity contracts is based on open derivative positions and represents the combined volume of our long and short open positions on an absolute basis, which totaled 0.7 million barrels and 1.2 million barrels as of December 31, 2018 and 2017, respectively. We had no margin deposits as of December 31, 2018 and $0.3 million of margin deposits as of December 31, 2017.

The fair values of our derivative instruments included in our consolidated balance sheets were as follows:



		Asset Derivatives				Liability Derivatives
	Balance Sheet Location	December 31,
	Balance Sheet Location	2018		2017		2018			2017
		(Thousands of Dollars)
Derivatives Designated as Hedging Instruments:
Commodity contracts	Other current assets	$	109	$	—	$	—		$	—
Interest rate swaps	Other long-term assets, net	627		—		—			—
Commodity contracts	Accrued liabilities	—		—		—			(112		)
Interest rate swaps	Accrued liabilities	—		—		—			(5,394		)
Interest rate swaps	Other long-term liabilities	—		—		(751		)	(4,594		)
Total		736		—		(751		)	(10,100		)

Derivatives Not Designated as Hedging Instruments:
Commodity contracts	Other current assets	1,652		—		(1,631		)	—
Commodity contracts	Accrued liabilities	—		742		—			(1,508		)
Total		1,652		742		(1,631		)	(1,508		)

Total Derivatives		$	2,388	$	742	$	(2,382	)	$	(11,608	)

Certain of our derivative instruments are eligible for offset in the consolidated balance sheets and subject to master netting arrangements. Under our master netting arrangements, there is a legally enforceable right to offset amounts, and we intend to settle such amounts on a net basis. The following are the net amounts presented on the consolidated balance sheets:



	December 31,
Commodity Contracts	2018		2017
	(Thousands of Dollars)
Net amounts of assets presented in the consolidated balance sheets	$	130	$	—
Net amounts of liabilities presented in the consolidated balance sheets	$	—	$	(878	)

We recognize the impact of our commodity contracts on earnings in “Cost of product sales” on the consolidated income statements, and that impact was as follows:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Derivatives Designated as Fair Value Hedging Instruments:
(Loss) gain recognized in income on derivative	$	(535	)	$	806		$	(11,254	)
(Loss) gain recognized in income on hedged item	(181		)	(656		)	15,295
(Loss) gain recognized in income for ineffective portion	$	(716	)	$	150		$	4,041

Derivatives Not Designated as Hedging Instruments:
(Loss) gain recognized in income on derivative	$	(601	)	$	(668	)	$	225

Our interest rate swaps had the following impact on earnings:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Derivatives Designated as Cash Flow Hedging Instruments:
Gain (loss) recognized in other comprehensive income (loss) on derivative (effective portion)	$	17,912		$	(8,670	)	$	(2,621	)
Loss reclassified from AOCI into interest expense, net (effective portion)	$	(5,499	)	$	(6,624	)	$	(8,331	)

As of December 31, 2018, we expect to reclassify a loss of $3.5 million to “Interest expense, net” within the next twelve months associated with unwound forward-starting interest rate swaps.

OTHER INCOME (EXPENSE)

12 Months Ended

Dec. 31, 2018

Other Income and Expenses [Abstract]

OTHER INCOME (EXPENSE)

Other income (expense) consisted of the following:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Gain (loss) related to hurricane activity	$	78,756		$	(5,000	)	$	—
Impairment loss on Axeon Term Loan	—			—			(58,655		)
Loss on sale of European operations	(43,366		)	—			—
Other, net	4,486			(294		)	(128		)
Other income (expense), net	$	39,876		$	(5,294	)	$	(58,783	)

Hurricane Activity. In the third quarter of 2017, several of our facilities were affected by the hurricanes in the Caribbean and Gulf of Mexico, including our St. Eustatius terminal, which experienced the most damage and was temporarily shut down. In 2017, we recorded a $5.0 million loss in “Other income (expense), net” in the consolidated statements of income for property damage at the terminal. In 2018, we recorded a $78.8 million gain in “Other income (expense), net” in the consolidated statements of income following the settlement of our property damage claim for our St. Eustatius terminal. See Note 1 for additional information.

Axeon Term Loan. In December 2016, Lindsay Goldberg LLC, the private investment firm that owned Axeon, informed us that they entered into an agreement to sell Axeon’s retail asphalt sales and distribution business (the Axeon Sale), and we entered into an agreement with Axeon (the Axeon Letter Agreement) to settle and terminate the Axeon Term Loan for a $110.0 million payment to us upon closing of the Axeon Sale. Therefore, we recorded a charge of $58.7 million, included in “Other income (expense), net” in the consolidated statements of income, to reduce the carrying amount of the Axeon Term Loan to $110.0 million. The Axeon Sale closed on February 22, 2017, at which time we received the $110.0 million payment in accordance with the Axeon Letter Agreement. Furthermore, the Axeon Term Loan and our obligation to provide ongoing credit support to Axeon all terminated concurrently on February 22, 2017.

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS

12 Months Ended

Dec. 31, 2018

Temporary Equity Disclosure [Abstract]

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS

Purchase Agreement and Issuance of Series D Preferred Units

On June 26, 2018, the Partnership entered into a purchase agreement (the Series D Preferred Unit Purchase Agreement) with investment funds, accounts and entities (collectively, the Purchasers) managed by EIG Management Company, LLC and FS/EIG Advisors, LLC to issue and sell $590.0 million of Series D Preferred Units in a private placement. The Partnership issued a total of 23,246,650 Series D Preferred Units to the Purchasers at a price of $25.38 per Series D Preferred Unit (the Series D Preferred Unit Purchase Price). At the initial closing on June 29, 2018 (the Initial Closing), the Purchasers purchased 15,760,441 Series D Preferred Units for $400.0 million, and we received net proceeds of $370.7 million. The Purchasers purchased the remaining 7,486,209 Series D Preferred Units for $190.0 million at a second closing on July 13, 2018. The net proceeds to the Partnership from the sale of the Series D Preferred Units of $555.8 million, including deductions for a 3.5% transaction fee of $20.7 million paid to the Purchasers and other issuance costs of $13.5 million, were used for general partnership purposes, including repayment of outstanding borrowings under our Revolving Credit Agreement.

Series D Preferred Units Rights

At the Initial Closing and pursuant to the Series D Preferred Unit Purchase Agreement, the Partnership amended and restated its partnership agreement to authorize and establish the rights, preferences and privileges of the Series D Preferred Units. The Series D Preferred Units rank equal to other classes of preferred units and senior to common units in the Partnership with respect to distribution rights and rights upon liquidation. The Series D Preferred Units generally will vote on an as-converted basis with the common units and will have certain class voting rights with respect to a limited number of matters as set forth in the partnership agreement.

Series D Preferred Units Distributions

Distributions on the Series D Preferred Units accrue and are cumulative from the issuance dates and are payable on the 15th day (or next business day) of each of March, June, September and December, beginning September 17, 2018 to holders of record on the first business day of each payment month. The distribution rate on the Series D Preferred Units is: (i) 9.75% per annum for the first two years; (ii) 10.75% per annum for years three through five; and (iii) the greater of 13.75% per annum or the distribution per common unit thereafter. While the Series D Preferred Units are outstanding, the Partnership will be prohibited from paying distributions on any junior securities, including the common units, unless full cumulative distributions on the Series D Preferred Units (and any parity securities) have been, or contemporaneously are being, paid or set aside for payment through the most recent Series D Preferred Unit distribution payment date. For the four distribution periods beginning with the initial Series D Preferred Unit distribution, the Series D Preferred Unit distributions may be paid, in the Partnership’s sole discretion, in (i) cash or (ii) a combination of additional Series D Preferred Units and cash, provided that up to 50% of the distribution amount may be paid in additional Series D Preferred Units. Thereafter, any Series D Preferred Unit distributions in excess of $0.635 per unit may be paid, in the Partnership’s sole discretion, in additional Series D Preferred Units, with the remainder paid in cash.

If we fail to pay in full any Series D Preferred Unit distribution amount, then, until we pay such distributions in full, the applicable distribution rate for each of those distribution periods shall be increased by $0.048 per Series D Preferred Unit. In addition, if we fail to pay in full any Series D Preferred Unit distribution amount for three consecutive distribution periods, then until we pay such distributions in full: (i) each holder of the Series D Preferred Units may elect to convert its Series D Preferred Units into common units on a one-for-one basis, plus any unpaid Series D distributions, (ii) one person selected by the holders holding a majority of the outstanding Series D Preferred Units shall become an additional member of our board of directors and (iii) we will not be permitted to incur any indebtedness (as defined in the Revolving Credit Agreement) or engage in any acquisitions or asset sales in excess of $50.0 million without the consent of the holders holding a majority of the outstanding Series D Preferred Units. In addition, we will permanently lose the ability to pay any part of the distributions on the Series D Preferred Units in the form of additional Series D Preferred Units.

The following table summarizes information about cash distributions declared for our Series D Preferred Units:



Period	Cash Distributions Per Unit		Total Cash Distributions		Record Date	Payment Date
			(Thousands of Dollars)
December 15, 2018 - March 14, 2019	$	0.619	$	14,390	March 1, 2019	March 15, 2019
September 15, 2018 - December 14, 2018	$	0.619	$	14,390	December 3, 2018	December 17, 2018
July 13, 2018 - September 14, 2018 (a)	$	0.431	$	3,227	September 4, 2018	September 17, 2018
June 29, 2018 - September 14, 2018 (b)	$	0.525	$	8,274	September 4, 2018	September 17, 2018


(a)	Second issuance of 7,486,209 units.


(b)	First issuance of 15,760,441 units.

Series D Preferred Units Conversion and Redemption Features

At any time on or after June 29, 2020, each holder of Series D Preferred Units may convert all or any portion of its Series D Preferred Units into common units on a one-for-one basis (plus any unpaid Series D distributions), subject to anti-dilution adjustments, at any time, but not more than once per quarter, so long as any conversion is for at least $50.0 million based on the Series D Preferred Unit Purchase Price (or such lesser amount representing all of a holder’s Series D Preferred Units).

The Partnership may redeem all or any portion of the Series D Preferred Units, in an amount not less than $50.0 million for cash at a redemption price equal to, as applicable: (i) $31.73 per Series D Preferred Unit at any time on or after June 29, 2023 but prior to June 29, 2024; (ii) $30.46 per Series D Preferred Unit at any time on or after June 29, 2024 but prior to June 29, 2025; (iii) $29.19 per Series D Preferred Unit at any time on or after June 29, 2025; plus, in each case, the sum of any unpaid distributions on the applicable Series D Preferred Unit plus the distributions prorated for the number of days elapsed (not to exceed 90) in the period of redemption (Series D Partial Period Distributions). The holders have the option to convert the units prior to such redemption as discussed above.

Additionally, at any time on or after June 29, 2028, each holder of Series D Preferred Units will have the right to require the Partnership to redeem all of the Series D Preferred Units held by such holder at a redemption price equal to $29.19 per Series D Preferred Unit plus any unpaid Series D distributions plus the Series D Partial Period Distributions. If a holder of Series D Preferred Units exercises its redemption right, the Partnership may elect to pay up to 50% of such amount in common units (which shall be valued at 93% of a volume-weighted average trading price of the common units); provided, that the common units to be issued do not, in the aggregate, exceed 15% of NuStar Energy’s common equity market capitalization at the time.

Series D Preferred Units Change of Control

Upon certain events involving a change of control, each holder of the Series D Preferred Units may elect to: (i) convert its Series D Preferred Units into common units on a one-for-one basis, plus any unpaid Series D distributions; (ii) require the Partnership to redeem its Series D Preferred Units for an amount equal to the sum of (a) $29.82 per Series D Preferred Unit plus (b) any unpaid Series D distributions plus (c) the applicable distribution amount for the distribution periods ending after the change of control event and prior to (but including) the fourth anniversary of the Initial Closing; (iii) if the Partnership is the surviving entity and its common units continue to be listed, continue to hold its Series D Preferred Units; or (iv) if the Partnership will not be the surviving entity, or it will be the surviving entity but its common units will cease to be listed, require the Partnership to use its commercially reasonable efforts to deliver a security in the surviving entity that has substantially similar terms as the Series D Preferred Units; however, if the Partnership is unable to deliver a mirror security, each holder is still entitled to option (i) or (ii) above.

Registration Rights Agreement

On June 29, 2018, in connection with the Initial Closing and pursuant to the Series D Preferred Unit Purchase Agreement, the Partnership entered into a Registration Rights Agreement (the Registration Rights Agreement) with the Purchasers relating to the registration of the Series D Preferred Units and common units issuable upon conversion of the Series D Preferred Units (the Common Unit Registrable Securities, and, collectively with the Series D Preferred Units, the Registrable Securities). Pursuant to the Registration Rights Agreement, the Partnership is required to use its commercially reasonable efforts to file a registration statement and to cause such registration statement to become effective: (i) with respect to the Common Unit Registrable Securities, no later than one year after the Initial Closing; and (ii) with respect to the Series D Preferred Units, after the second anniversary of the Initial Closing, no later than one year after receipt by the Partnership of a written request from holders holding a majority of the Series D Preferred Units to register the Series D Preferred Units. If the Partnership fails to cause such registration statements to become effective by such dates, the Partnership will be required to pay certain amounts to the holders of the Registrable Securities as liquidated damages.

Series D Preferred Units Accounting Treatment

The Series D Preferred Units include redemption provisions at the option of the holders of the Series D Preferred Units and upon a Series D Change of Control (as defined in the partnership agreement), which are outside the Partnership’s control. Therefore, the Series D Preferred Units are presented in the mezzanine section of the consolidated balance sheets. The Series D Preferred Units have been recorded at their issuance date fair value, net of issuance costs. We reassess the presentation of the Series D Preferred Units in our consolidated balance sheets on a quarterly basis.

The Series D Preferred Units are subject to accretion from their carrying value at the issuance date to the redemption value, which is based on the redemption right of the Series D Preferred Unit holders that may be exercised at any time on or after June 29, 2028, using the effective interest method over a period of ten years. In the calculation of net income per unit, the accretion is treated in the same manner as a distribution and deducted from net income to arrive at net income attributable to common units.

PARTNERS' EQUITY

12 Months Ended

Dec. 31, 2018

Partners' Capital Notes [Abstract]

PARTNERS' EQUITY

PARTNERS’ EQUITY

Please refer to Note 4 for a discussion of the Merger.

Partnership Agreement Amendments

In the third quarter of 2018, NuStar Energy’s partnership agreement was amended and restated to, among other things, (i) cancel the incentive distribution rights held by our general partner, (ii) convert the 2% general partner interest in NuStar Energy held by our general partner into a non-economic management interest and (iii) provide the holders of our common units with voting rights in the election of the members of the board of directors of NuStar GP, LLC, beginning at the annual meeting in 2019. The partnership agreement was also amended and restated in the second quarter of 2018 in connection with the issuance of our Series D Preferred Units discussed in Note 19. In 2017, the partnership agreement was amended and restated in connection with the issuances of our Series B Preferred Units and Series C Preferred Units described below, and in connection with the Navigator Acquisition to waive up to an aggregate $22.0 million of the quarterly incentive distributions to our general partner for any NS common units issued from the date of the Acquisition Agreement, starting with the distributions for the second quarter of 2017.

Series A, B and C Preferred Units

The following is a summary of our Series A, Series B and Series C Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units (collectively the Series A, B and C Preferred Units) issued and outstanding as of December 31, 2018:



Units	Original Issuance Date	Number of Units Issued and Outstanding	Price per Unit		Net Proceeds (in millions)		Fixed Distribution Rate per Annum (as a Percentage of the $25.00 Liquidation Preference per Unit)		Fixed Distribution Rate per Unit per Annum		Optional Redemption Date/Date at Which Distribution Rate Becomes Floating	Floating Annual Rate (as a Percentage of the $25.00 Liquidation Preference per Unit)
Series A Preferred Units	November 25, 2016	9,060,000	$	25.00	$	218.4	8.50	%	$	2.125	December 15, 2021	Three-month LIBOR plus 6.766%
Series B Preferred Units	April 28, 2017	15,400,000	$	25.00	$	371.8	7.625	%	$	1.90625	June 15, 2022	Three-month LIBOR plus 5.643%
Series C Preferred Units	November 30, 2017	6,900,000	$	25.00	$	166.7	9.00	%	$	2.25	December 15, 2022	Three-month LIBOR plus 6.88%

We may redeem any of our outstanding Series A, B and C Preferred Units at any time on or after the optional redemption date set forth above for each series of the Series A, B and C Preferred Units, in whole or in part, at a redemption price of $25.00 per unit plus an amount equal to all accumulated and unpaid distributions to, but not including, the date of redemption, whether or not declared. We may also redeem the Series A, B and C Preferred Units upon the occurrence of certain rating events or a change of control as defined in our partnership agreement. In the case of the latter instance, if we choose not to redeem the Series A, B and C Preferred Units, those preferred unitholders may have the ability to convert their Series A, B and C Preferred Units to common units at the then applicable conversion rate. Holders of the Series A, B and C Preferred Units have no voting rights except for certain exceptions set forth in our partnership agreement.

The following table summarizes financial information related to our Series A, B and C Preferred Units:



	Preferred Limited Partners
	Series A			Series B			Series C			Total
	(Thousands of Dollars)
Balance as of January 1, 2016	$	—		$	—		$	—		$	—
Issuance of units	218,400			—			—			218,400
Net income	1,925			—			—			1,925
Distributions to partners	(1,925		)	—			—			(1,925		)
Balance as of December 31, 2016	218,400			—			—			218,400
Issuance of units	—			371,823			166,737			538,560
Net income	19,253			19,815			1,380			40,448
Distributions to partners	(19,253		)	(19,815		)	(1,380		)	(40,448		)
Other	(93		)	(189		)	(75		)	(357		)
Balance as of December 31, 2017	218,307			371,634			166,662			756,603
Net income	19,253			29,357			15,481			64,091
Distributions to partners	(19,253		)	(29,357		)	(15,481		)	(64,091		)
Other	—			(158		)	(144		)	(302		)
Balance as of December 31, 2018	$	218,307		$	371,476		$	166,518		$	756,301

Distributions on the Series A, B and C Preferred Units are payable out of any legally available funds, accrue and are cumulative from the original issuance dates, and are payable on the 15th day (or the next business day) of each of March, June, September and December of each year to holders of record on the first business day of each payment month. The Series A, B and C Preferred Units rank equal to each other and to the Series D Preferred Units, and senior to all of our other classes of equity securities with respect to distribution rights and rights upon liquidation. The following table summarizes information about cash distributions declared for our Series A, B and C Preferred Units:



	Cash Distributions Per Unit
Period	Series A		Series B		Series C
December 15, 2018 - March 14, 2019	$	0.53125	$	0.47657	$	0.56250
September 15, 2018 - December 14, 2018	$	0.53125	$	0.47657	$	0.56250
June 15, 2018 - September 14, 2018	$	0.53125	$	0.47657	$	0.56250
March 15, 2018 - June 14, 2018	$	0.53125	$	0.47657	$	0.56250
December 15, 2017 - March 14, 2018	$	0.53125	$	0.47657	N/A
November 30, 2017 - March 14, 2018	N/A		N/A		$	0.65625

Common Units and General Partner

Issuances of Common Units. As a result of the Merger discussed in Note 4, we issued approximately 13.4 million incremental NuStar Energy common units in the third quarter of 2018, in exchange for the previously outstanding NSH units.

In the second quarter of 2018, we issued 413,736 common units at a price of $24.17 per unit to William E. Greehey, Chairman of the Board of Directors of NuStar GP, LLC. We used the proceeds of $10.2 million from the sale of these units, including a contribution of $0.2 million from our general partner to maintain the 2% general partner economic interest it owned at that time, for general partnership purposes.

In the second quarter of 2017, we issued 14,375,000 common units at a price of $46.35 per unit. We used the net proceeds from this offering of $657.5 million, including a contribution of $13.6 million from our general partner to maintain the 2% general partner economic interest it owned at that time, to fund a portion of the purchase price for the Navigator Acquisition.

In the third quarter of 2016, we issued 595,050 common units at an average price of $47.39 per unit for proceeds of $28.3 million, net of $0.5 million of issuance costs. We used these proceeds, which include a contribution of $0.6 million from our general partner to maintain the 2% general partner economic interest it owned at that time, for general partnership purposes, including repayments of outstanding borrowings under the Revolving Credit Agreement.

For the years ended December 31, 2018, 2017 and 2016, we issued 225,144, 185,455 and 135,100 common units, respectively, in connection with the vestings of awards issued under our long-term incentive plans.

Cash Distributions. We make quarterly distributions to common unitholders, and, prior to the Merger, made quarterly distributions to the general partner of 100% of our “Available Cash,” generally defined as cash receipts less cash disbursements, including distributions to our preferred units, and cash reserves established by the general partner, in its sole discretion. These quarterly distributions are declared and paid within 45 days subsequent to each quarter-end. The common unitholders receive a distribution each quarter as determined by the board of directors, subject to limitation by the distributions in arrears, if any, on our preferred units. Prior to the Merger, our Available Cash was distributed based on the percentages shown below:



	Percentage of Distribution
Quarterly Distribution Amount Per Common Unit	Common Unitholders	General Partner Including Incentive Distributions
Up to $0.60	98%	2%
Above $0.60 up to $0.66	90%	10%
Above $0.66	75%	25%

Because the Merger was effective prior to the record date for the distribution for the second quarter of 2018, the general partner received no distributions after the first quarter distribution. Beginning with the second quarter of 2018, the common limited partners’ distribution includes the additional common units issued in exchange for previously outstanding NSH units because the Merger closed prior to the common unit distribution record date for the second quarter of 2018.

The following table reflects the allocation of total cash distributions to the general partner and common limited partners applicable to the period in which the distributions were earned:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars, Except Per Unit Data)
General partner interest	$	1,141	$	9,252	$	7,877
General partner incentive distribution	—		45,669		43,407
Total general partner distribution	1,141		54,921		51,284
Common limited partners’ distribution	248,705		407,681		342,598
Total cash distributions	$	249,846	$	462,602	$	393,882

Cash distributions per unit applicable to common limited partners	$	2.40	$	4.38	$	4.38

The following table summarizes information about quarterly cash distributions declared for our common limited partners, and prior to the Merger, our general partner:



Quarter Ended	Cash Distributions Per Unit		Total Cash Distributions		Record Date	Payment Date
			(Thousands of Dollars)
December 31, 2018	$	0.60	$	64,336	February 8, 2019	February 13, 2019
September 30, 2018	$	0.60	$	64,248	November 8, 2018	November 14, 2018
June 30, 2018	$	0.60	$	64,205	August 7, 2018	August 13, 2018
March 31, 2018	$	0.60	$	57,057	May 8, 2018	May 14, 2018

Net Income Applicable to the General Partner. For the year ended December 31, 2018, net income applicable to the general partner totaled $2.5 million and related to the general partner interest allocation prior to the Merger. The following table details the calculation of net income applicable to the general partner for 2017 and 2016:



	Year Ended December 31,
	2017			2016
	(Thousands of Dollars)
Net income attributable to NuStar Energy L.P.	$	147,964		$	150,003
Less preferred limited partner interest	40,448			1,925
Less general partner incentive distribution	45,669			43,407
Net income after general partner incentive distribution and preferred limited partner interest	61,847			104,671
General partner interest allocation	2		%	2		%
General partner interest allocation of net income	1,237			2,091
General partner incentive distribution	45,669			43,407
Net income applicable to general partner	$	46,906		$	45,498

Accumulated Other Comprehensive Income (Loss)

The balance of and changes in the components included in AOCI were as follows:



	Foreign Currency Translation			Cash Flow Hedges			Pension and Other Postretirement Benefits			Total
	(Thousands of Dollars)
Balance as of January 1, 2016	$	(60,826	)	$	(27,968	)	$	—		$	(88,794	)
Employee Transfer	—			—			4,201			4,201
Deferred income tax adjustments	—			—			2,414			2,414
Other comprehensive loss before reclassification adjustments	(8,243		)	(2,621		)	(7,852		)	(18,716		)
Net gain on pension costs reclassified into operating expense	—			—			(1,200		)	(1,200		)
Net gain on pension costs reclassified into general and administrative expense	—			—			(413		)	(413		)
Net loss on cash flow hedges reclassified into interest expense, net	—			8,331			—			8,331
Other comprehensive (loss) income	(8,243		)	5,710			(2,850		)	(5,383		)
Balance as of December 31, 2016	(69,069		)	(22,258		)	(2,850		)	(94,177		)
Other comprehensive income (loss) before reclassification adjustments	17,466			(8,670		)	(4,641		)	4,155
Net gain on pension costs reclassified into operating expense	—			—			(1,143		)	(1,143		)
Net gain on pension costs reclassified into general and administrative expense	—			—			(386		)	(386		)
Net loss on cash flow hedges reclassified into interest expense, net	—			6,624			—			6,624
Other comprehensive income (loss)	17,466			(2,046		)	(6,170		)	9,250
Balance as of December 31, 2017	(51,603		)	(24,304		)	(9,020		)	(84,927		)
Other comprehensive income before reclassification adjustments	(13,880		)	17,912			3,282			7,314
Sale of European operations reclassified into other income, net	18,124			—			—			18,124
Net gain on pension costs reclassified into other income, net	—			—			(814		)	(814		)
Net loss on cash flow hedges reclassified into interest expense, net	—			5,499			—			5,499
Other	60			—			(134		)	(74		)
Other comprehensive income	4,304			23,411			2,334			30,049
Balance as of December 31, 2018	$	(47,299	)	$	(893	)	$	(6,686	)	$	(54,878	)

NET (LOSS) INCOME PER UNIT

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

NET (LOSS) INCOME PER UNIT

NET (LOSS) INCOME PER COMMON UNIT

As discussed in Note 19, the Series D Preferred Units are convertible into common units at the option of the holder at any time on or after June 29, 2028. As such, we calculated the dilutive effect of the Series D Preferred Units using the if-converted method. For the year ended December 31, 2018, the effect of the assumed conversion of the 23,246,650 Series D Preferred Units outstanding as of December 31, 2018 was antidilutive; therefore, we did not include such conversion in the computation of diluted net (loss) income per common unit.

The following table details the calculation of net (loss) income per common unit:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars, Except Unit and Per Unit Data)
Net income	$	205,794		$	147,964		$	150,003
Distributions to preferred limited partners	(92,540		)	(40,448		)	(1,925		)
Distributions to general partner (including incentive distribution rights)	(1,141		)	(54,921		)	(51,284		)
Distributions to common limited partners	(248,705		)	(407,681		)	(342,598		)
Distribution equivalent rights to restricted units	(2,045		)	(2,965		)	(2,697		)
Distributions in excess of earnings	$	(138,637	)	$	(358,051	)	$	(248,501	)

Distributions to common limited partners	$	248,705		$	407,681		$	342,598
Allocation of distributions in excess of earnings	(138,659		)	(350,890		)	(243,530		)
Series D Preferred Unit accretion (refer to Note 19)	(8,195		)	—			—
Loss to common unitholders attributable to the Merger (refer to Note 4)	(377,079		)	—			—
Net (loss) income attributable to common units:	$	(275,228	)	$	56,791		$	99,068

Basic weighted-average common units outstanding	99,490,495			88,825,964			78,080,484

Diluted common units outstanding:
Basic weighted-average common units outstanding	99,490,495			88,825,964			78,080,484
Effect of dilutive potential common units	40,677			—			32,518
Diluted weighted-average common units outstanding	99,531,172			88,825,964			78,113,002

Basic and diluted net (loss) income per common unit	$	(2.77	)	$	0.64		$	1.27

STATEMENTS OF CASH FLOWS

12 Months Ended

Dec. 31, 2018

Statement of Cash Flows [Abstract]

STATEMENTS OF CASH FLOWS

Changes in current assets and current liabilities were as follows:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Decrease (increase) in current assets:
Accounts receivable	$	22,482		$	(865	)	$	(23,234	)
Receivable from related parties	160			112			(317		)
Inventories	3,819			11,936			940
Prepaid and other current assets	3,694			3,393			8,128
Increase (decrease) in current liabilities:
Accounts payable	8,003			(30,409		)	14,071
Payable to related party	—			—			894
Accrued interest payable	(4,279		)	6,489			(256		)
Accrued liabilities	39,577			(11,157		)	161
Taxes other than income tax	4,521			(3,529		)	2,690
Income tax payable	285			(2,463		)	639
Changes in current assets and current liabilities	$	78,262		$	(26,493	)	$	3,716

The above changes in current assets and current liabilities differ from changes between amounts reflected in the applicable consolidated balance sheets due to:


•	current assets and current liabilities acquired and disposed of during the period;


•	the change in the amount accrued for capital expenditures;


•	the effect of foreign currency translation;


•	reclassification of the Axeon Term Loan to other current assets from other long-term assets, net in 2016;


•	changes in the fair values of our interest rate swap agreements; and


•	non-cash related party transactions associated with the Employee Transfer.

Cash flows related to interest and income taxes were as follows:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars)
Cash paid for interest, net of amount capitalized	$	183,078	$	158,089	$	142,663
Cash paid for income taxes, net of tax refunds received	$	8,535	$	11,338	$	11,847

EMPLOYEE BENEFIT PLANS

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

EMPLOYEE BENEFIT PLANS

Employee Transfer

Prior to the Employee Transfer discussed in Note 1, we reimbursed all costs incurred by NuStar GP, LLC related to the pension plans and other postretirement benefit plans at cost. For comparability purposes this footnote presents information related to these benefit plans on a combined basis for periods during 2016 prior to the Employee Transfer and after the Employee Transfer, including the components of net periodic benefit cost (income) and adjustments to other comprehensive income (loss). Consequently, certain amounts presented below will differ from amounts reflected in our consolidated financial statements. See Note 4 for additional discussion on the Employee Transfer.

Thrift Plans

The NuStar Thrift Plan (the Thrift Plan) is a qualified defined contribution plan that became effective June 26, 2006. Participation in the Thrift Plan is voluntary and open to substantially all our domestic employees upon their dates of hire. Thrift Plan participants can contribute from 1% up to 30% of their total annual compensation to the Thrift Plan in the form of pre-tax and/or after tax employee contributions. We make matching contributions in an amount equal to 100% of each participant’s employee contributions up to a maximum of 6% of the participant’s total annual compensation. The matching contributions to the Thrift Plan for the years ended December 31, 2018, 2017 and 2016 totaled $7.4 million, $6.9 million and $6.6 million, respectively.

The NuStar Excess Thrift Plan (the Excess Thrift Plan) is a nonqualified deferred compensation plan that became effective July 1, 2006. The Excess Thrift Plan provides benefits to those employees whose compensation and/or annual contributions under the Thrift Plan are subject to the limitations applicable to qualified retirement plans under the Code.

We also maintain other defined contribution plans for certain international employees located in Canada and the Caribbean Netherlands. We also maintained plans for international employees in the United Kingdom and Netherlands prior to the sale of our European operations on November 30, 2018. For the years ended December 31, 2018, 2017 and 2016, our costs for these plans totaled $2.5 million, $2.5 million and $2.4 million, respectively.

Pension and Other Postretirement Benefits

The NuStar Pension Plan (the Pension Plan) is a qualified non-contributory defined benefit pension plan that provides eligible U.S. employees with retirement income as calculated under a cash balance formula. Under the cash balance formula, benefits are determined based on age, years of vesting service and interest credits, and employees become fully vested in their benefits upon attaining three years of vesting service. Prior to January 1, 2014, eligible employees were covered under either a cash balance formula or a final average pay formula (FAP). Effective January 1, 2014, the Pension Plan was amended to freeze the FAP benefits as of December 31, 2013, and going forward, all eligible employees are covered under the cash balance formula discussed above.

We also maintain an excess pension plan (the Excess Pension Plan), which is a nonqualified deferred compensation plan that provides benefits to a select group of management or other highly compensated employees. Neither the Excess Thrift Plan nor the Excess Pension Plan is intended to constitute either a qualified plan under the provisions of Section 401 of the Code or a funded plan subject to the Employee Retirement Income Security Act.

The Pension Plan and Excess Pension Plan are collectively referred to as the Pension Plans in the tables and discussion below. Our other postretirement benefit plans include a contributory medical benefits plan for U.S. employees who retired prior to April 1, 2014 and, for employees who retire on or after April 1, 2014, a partial reimbursement for eligible third-party health care premiums. We use December 31 as the measurement date for our pension and other postretirement plans.

The changes in the benefit obligation, the changes in fair value of plan assets, the funded status and the amounts recognized in the consolidated balance sheets for our Pension Plans and other postretirement benefit plans as of and for the years ended December 31, 2018 and 2017 were as follows:



	Pension Plans						Other Postretirement Benefit Plans
	2018			2017			2018			2017
	(Thousands of Dollars)
Change in benefit obligation:
Benefit obligation, January 1	$	149,817		$	127,402		$	12,410		$	11,061
Service cost	9,621			8,955			504			456
Interest cost	4,824			4,507			429			430
Benefits paid	(7,929		)	(5,941		)	(255		)	(342		)
Participant contributions	—			—			87			215
Actuarial (gain) loss	(14,500		)	14,894			(2,267		)	590
Benefit obligation, December 31	$	141,833		$	149,817		$	10,908		$	12,410
Change in plan assets:
Plan assets at fair value, January 1	$	129,878		$	107,644		$	—		$	—
Actual return on plan assets	(6,034		)	17,070			—			—
Employer contributions	11,034			11,105			168			127
Benefits paid	(7,929		)	(5,941		)	(255		)	(342		)
Participant contributions	—			—			87			215
Plan assets at fair value, December 31	$	126,949		$	129,878		$	—		$	—
Reconciliation of funded status:
Fair value of plan assets at December 31	$	126,949		$	129,878		$	—		$	—
Less: Benefit obligation at December 31	141,833			149,817			10,908			12,410
Funded status at December 31	$	(14,884	)	$	(19,939	)	$	(10,908	)	$	(12,410	)
Amounts recognized in the consolidated balance sheets (a):
Accrued liabilities	$	(267	)	$	(210	)	$	(362	)	$	(376	)
Other long-term liabilities	(14,617		)	(19,729		)	(10,546		)	(12,034		)
Net pension liability	$	(14,884	)	$	(19,939	)	$	(10,908	)	$	(12,410	)


(a)	For the Pension Plan, since assets exceed the present value of expected benefit payments for the next 12 months, all of the liability is noncurrent. For the Excess Pension Plan and the other postretirement benefit plans, since there are no assets, the current liability is the present value of expected benefit payments for the next 12 months; the remainder is noncurrent.

The accumulated benefit obligation is the present value of benefits earned to date, assuming no future salary increases. The aggregate accumulated benefit obligation for our Pension Plans as of December 31, 2018 and 2017 was $139.7 million and $146.3 million, respectively. As of December 31, 2018 and 2017, the aggregate accumulated benefit obligation for the Pension Plans exceeded plan assets.

The components of net periodic benefit cost (income) related to our Pension Plans and other postretirement benefit plans were as follows:



	Pension Plans									Other Postretirement Benefit Plans
	Year Ended December 31,									Year Ended December 31,
	2018			2017			2016			2018			2017			2016
	(Thousands of Dollars)
Service cost	$	9,621		$	8,955		$	7,703		$	504		$	456		$	419
Interest cost	4,824			4,507			4,023			429			430			401
Expected return on plan assets	(7,417		)	(6,411		)	(5,407		)	—			—			—
Amortization of prior service credit	(2,057		)	(2,059		)	(2,063		)	(1,145		)	(1,145		)	(1,145		)
Amortization of net actuarial loss	2,174			1,484			1,091			214			191			181
Net periodic benefit cost (income)	$	7,145		$	6,476		$	5,347		$	2		$	(68	)	$	(144	)

We amortize prior service costs and credits on a straight-line basis over the average remaining service period of employees expected to receive benefits under our Pension Plans and other postretirement benefit plans (“Amortization of prior service credit” in table above). We amortize the actuarial gains and losses that exceed 10% of the greater of the projected benefit obligation or market-related value of plan assets (smoothed asset value) over the average remaining service period of active employees expected to receive benefits under our Pension Plans and other postretirement benefit plans (“Amortization of net actuarial loss” in table above).

Adjustments to other comprehensive income (loss) related to our Pension Plans and other postretirement benefit plans were as follows:



	Pension Plans									Other Postretirement Benefit Plans
	Year Ended December 31,									Year Ended December 31,
	2018			2017			2016			2018			2017			2016
	(Thousands of Dollars)
Net unrecognized gain (loss) arising during the year:
Net actuarial gain (loss)	$	1,049		$	(4,235	)	$	(7,544	)	$	2,267		$	(590	)	$	(368	)
Net (gain) loss reclassified into income:
Amortization of prior service credit	(2,057		)	(2,059		)	(2,063		)	(1,145		)	(1,145		)	(1,145		)
Amortization of net actuarial loss	2,174			1,484			1,091			214			191			181
Net loss (gain) reclassified into income	117			(575		)	(972		)	(931		)	(954		)	(964		)

Reclassification of stranded tax effects	(74		)	—			—			—			—			—
Income tax (expense) benefit	(69		)	162			57			(25		)	22			3
Total changes to other comprehensive income (loss)	$	1,023		$	(4,648	)	$	(8,459	)	$	1,311		$	(1,522	)	$	(1,329	)

The amounts recorded as a component of “Accumulated other comprehensive loss” on the consolidated balance sheets related to our Pension Plans and other postretirement benefit plans were as follows:



	Pension Plans						Other Postretirement Benefit Plans
	December 31,						December 31,
	2018			2017			2018			2017
	(Thousands of Dollars)
Unrecognized actuarial loss	$	(27,955	)	$	(31,178	)	$	(1,673	)	$	(4,154	)
Prior service credit	14,547			16,604			8,319			9,464
Deferred tax asset	76			219			—			25
Accumulated other comprehensive (loss) income, net of tax	$	(13,332	)	$	(14,355	)	$	6,646		$	5,335

The following pre-tax amounts in accumulated other comprehensive loss as of December 31, 2018 are expected to be recognized as components of net periodic benefit cost (income) in 2019:



	Pension Plans			Other Postretirement Benefit Plans
	(Thousands of Dollars)
Actuarial loss	$	846		$	42
Prior service credit	$	(2,057	)	$	(1,145	)

Investment Policies and Strategies

The investment policies and strategies for the assets of our qualified Pension Plan incorporate a well-diversified approach that is expected to earn long-term returns from capital appreciation and a growing stream of current income. This approach recognizes that assets are exposed to risk, and the market value of the Pension Plan’s assets may fluctuate from year to year. Risk tolerance is determined based on our financial ability to withstand risk within the investment program and the willingness to accept return volatility. In line with the investment return objective and risk parameters, the Pension Plan’s mix of assets includes a diversified portfolio of equity and fixed-income instruments. The aggregate asset allocation is reviewed on an annual basis. As of December 31, 2018, the target allocations for plan assets are 65% equity securities and 35% fixed income investments, with certain fluctuations permitted.

The overall expected long-term rate of return on plan assets for the Pension Plan is estimated using various models of asset returns. Model assumptions are derived using historical data with the assumption that capital markets are informationally efficient. Three models are used to derive the long-term expected returns for each asset class. Since each method has distinct advantages and disadvantages and differing results, an equal weighted average of the methods’ results is used.

Fair Value of Plan Assets

We disclose the fair value for each major class of plan assets in the Pension Plan into three levels: Level 1, defined as observable inputs such as quoted prices for identical assets or liabilities in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in markets that are not active; and Level 3, defined as unobservable inputs for which little or no market data exists.

The major classes of plan assets measured at fair value for the Pension Plan were as follows:



	December 31, 2018
	Level 1		Level 2		Level 3		Total
	(Thousands of Dollars)
Cash equivalent securities	$	608	$	—	$	—	$	608
Equity securities:
U.S. large cap equity fund (a)	—		70,525		—		70,525
International stock index fund (b)	13,391		—		—		13,391
Fixed income securities:
Bond market index fund (c)	42,425		—		—		42,425
Total	$	56,424	$	70,525	$	—	$	126,949



	December 31, 2017
	Level 1		Level 2		Level 3		Total
	(Thousands of Dollars)
Cash equivalent securities	$	381	$	—	$	—	$	381
Equity securities:
U.S. large cap equity fund (a)	—		75,353		—		75,353
International stock index fund (b)	14,480		—		—		14,480
Fixed income securities:
Bond market index fund (c)	39,664		—		—		39,664
Total	$	54,525	$	75,353	$	—	$	129,878


(a)	This fund is a low-cost equity index fund not actively managed that tracks the S&P 500. Fair values were estimated using pricing models, quoted prices of securities with similar characteristics or discounted cash flows.


(b)	This fund tracks the performance of the Total International Composite Index.


(c)	This fund tracks the performance of the Barclays Capital U.S. Aggregate Bond Index.

Contributions to the Pension Plans

For the year ended December 31, 2018, we contributed $11.0 million and $0.2 million to the Pension Plans and other postretirement benefit plans, respectively. During 2019, we expect to contribute approximately $11.3 million and $0.3 million to the Pension Plans and other postretirement benefit plans, respectively, which principally represent contributions either required by regulations or laws, or with respect to unfunded plans, necessary to fund current benefits.

Estimated Future Benefit Payments

The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid for the years ending December 31:



	Pension Plans		Other Postretirement Benefit Plans
	(Thousands of Dollars)
2019	$	9,454	$	362
2020	$	10,309	$	390
2021	$	11,072	$	423
2022	$	11,593	$	475
2023	$	12,274	$	503
Years 2024-2028	$	68,198	$	3,200

Assumptions

The weighted-average assumptions used to determine the benefit obligations were as follows:



	Pension Plans				Other Postretirement Benefit Plans
	December 31,				December 31,
	2018		2017		2018		2017
Discount rate	4.40	%	3.72	%	4.53	%	3.82	%
Rate of compensation increase	3.51	%	3.51	%	n/a		n/a

The weighted-average assumptions used to determine the net periodic benefit cost (income) were as follows:



	Pension Plans						Other Postretirement Benefit Plans
	Year Ended December 31,						Year Ended December 31,
	2018		2017		2016		2018		2017		2016
Discount rate	3.72	%	4.33	%	4.61	%	3.82	%	4.49	%	4.75	%
Expected long-term rate of return on plan assets	6.50	%	6.00	%	6.25	%	n/a		n/a		n/a
Rate of compensation increase	3.51	%	3.51	%	3.51	%	n/a		n/a		n/a

The assumed health care cost trend rates were as follows:



	December 31,
	2018		2017
Health care cost trend rate assumed for next year	6.84	%	6.84	%
Rate to which the cost trend rate was assumed to decrease (the ultimate trend rate)	5.00	%	5.00	%
Year that the rate reaches the ultimate trend rate	2028		2028

We sponsor a contributory postretirement health care plan for employees who retired prior to April 1, 2014. The plan has an annual limitation (a cap) on the increase of the employer’s share of the cost of covered benefits. The cap on the increase in employer’s cost is 2.5% per year. The assumed increase in total health care cost exceeds the 2.5% indexed cap, so increasing or decreasing the health care cost trend rate by 1% does not materially change our obligation or expense for the postretirement health care plan.

UNIT-BASED COMPENSATION

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

UNIT-BASED COMPENSATION

Overview

2000 LTIP. We sponsor the 2000 LTIP, which provides for the right to issue and award up to 3,250,000 of our common units to employees and non-employee directors (NEDs). Awards available under the 2000 LTIP include restricted units, performance units, unit options, unit awards and distribution equivalent rights (DERs). DERs entitle the participant to receive cash equal to cash distributions made on any award prior to its vesting. As of December 31, 2018, a total of 655,848 common units remained available to be awarded under the 2000 LTIP.

Prior to the Employee Transfer, NuStar GP, LLC sponsored the 2000 LTIP, and we reimbursed NuStar GP, LLC for awards under this plan. Most of our currently outstanding awards are classified as equity awards as we intend to settle these awards through the issuance of our common units. Effective March 1, 2016, we assumed sponsorship of the 2000 LTIP and assumed all outstanding awards under the 2000 LTIP. The transfer of the outstanding awards qualified as a plan modification. Therefore, we measured the fair value of the outstanding awards based on the common unit price on the transfer date. Please refer to Note 4 for a discussion of our related party agreements.

2006 LTIP. Effective July 20, 2018 and in conjunction with the Merger, we assumed the 2006 Long-Term Incentive Plan (the 2006 LTIP). Prior to the Merger, NuStar GP Holdings sponsored the 2006 LTIP, pursuant to which it could award up to 2,000,000 NSH units to its employees and NEDs. At the effective time of the Merger, each outstanding award of NuStar GP Holdings restricted units was converted, on the same terms and conditions as were applicable to the awards immediately prior to the Merger, into an award of NuStar Energy restricted units. The number of NuStar Energy restricted units subject to the converted awards was determined pursuant to the 0.55 exchange ratio provided in the Merger Agreement. The NSH units remaining available to be awarded under the 2006 LTIP were also converted pursuant to the exchange ratio provided in the Merger Agreement. Awards available under the 2006 LTIP include restricted units, performance units, unit options, unit awards and DERs. As of December 31, 2018, a total of 219,632 NS units remained available to be awarded under the 2006 LTIP.

The following table summarizes information pertaining to both long-term incentive plans:



	Units Outstanding December 31,			Compensation Expense Year Ended December 31,
	2018	2017	2016	2018		2017		2016
				(Thousands of Dollars)
Restricted Units:
Domestic employees	1,028,484	736,746	647,340	$	8,233	$	7,881	$	5,980
Non-employee directors (NEDs)	59,752	27,097	18,134	524		251		388
International employees	30,918	58,107	50,609	1,158		595		715
Performance Units	158,326	80,961	77,014	1,889		—		1,211
Unit Awards	—	—	—	1,358		—		—
Total	1,277,480	902,911	793,097	$	13,162	$	8,727	$	8,294

Restricted Units

Our restricted unit awards are considered phantom units, as they represent the right to receive our common units upon vesting. We account for restricted units as either equity-classified awards or liability-classified awards, depending on expected method of settlement. Awards we settle with the issuance of common units upon vesting are equity-classified. Awards we settle in cash upon vesting are liability-classified. We record compensation expense ratably over the vesting period based on the fair value of the common units at the grant date (for domestic employees) or the fair value of the common units measured at each reporting period (for NEDs and international employees). DERs paid with respect to outstanding equity-classified unvested restricted units reduce equity, similar to cash distributions to unitholders, whereas DERs paid with respect to outstanding liability-classified unvested restricted units are expensed. In connection with the DERs for equity awards, we paid $2.0 million and $3.0 million, respectively, in cash, for the years ended December 31, 2018 and 2017.

Domestic Employees. The outstanding restricted units granted to domestic employees are equity-classified awards and generally vest over five years, beginning one year after the grant date. The fair value of these awards is measured at the grant date (or transfer date for issuances prior to the Employee Transfer).

Non-Employee Directors. The outstanding restricted units granted to NEDs are equity-classified awards that vest over three years. The fair value of these awards is equal to the market price of our common units at each reporting period.

International Employees. The outstanding restricted units granted to international employees are cash-settled and accounted for as liability-classified awards. These awards vest over three to five years and the fair value is equal to the market price of our common units at each reporting period.

A summary of our restricted unit activity is as follows:



	Domestic Employees
	Number of Restricted Units		Weighted- Average Grant-Date Fair Value Per Unit		Number of Restricted Units to NEDs		Number of Restricted Units to International Employees
Nonvested units as of January 1, 2016	—		$	—	—		—
Transferred on March 1, 2016	586,524		35.03		17,629		49,121
Granted	246,070		47.70		8,730		20,107
Vested	(180,724	)	35.50		(8,225	)	(14,812	)
Forfeited	(4,530	)	35.03		—		(3,807	)
Nonvested units as of December 31, 2016	647,340		39.72		18,134		50,609
Granted	307,009		29.56		17,110		24,533
Vested	(201,466	)	38.74		(8,147	)	(16,440	)
Forfeited	(16,137	)	40.00		—		(595	)
Nonvested units as of December 31, 2017	736,746		35.95		27,097		58,107
Converted on July 20, 2018	53,447		24.99		18,915		—
Granted	518,282		24.07		34,303		16,197
Vested	(235,746	)	35.12		(20,563	)	(41,406	)
Forfeited	(44,245	)	36.05		—		(1,980	)
Nonvested units as of December 31, 2018	1,028,484		$	29.47	59,752		30,918

The total fair value of our equity-classified restricted unit awards vested for the years ended December 31, 2018, 2017 and 2016 was $7.5 million, $6.5 million and $9.0 million, respectively. We issued 189,399 common units in connection with these award vestings, net of employee tax withholding requirements, for the year ended December 31, 2018. Unrecognized compensation cost related to our equity-classified employee awards totaled $29.2 million as of December 31, 2018, which we expect to recognize over a weighted-average period of 3.8 years.

Performance Units

Performance units are issued to certain of our key employees and represent rights to receive our common units upon achieving a performance measure for the performance period. The performance measure is determined each year by the NuStar GP, LLC Compensation Committee for the following year. Achievement of the performance measure determines the rate at which the performance units convert into our common units, which ranges from zero to 200% for certain awards.

Performance units awarded vest in three annual increments (tranches), based upon our achievement of the performance measure set by the Compensation Committee during the one-year performance periods that end on December 31 of each applicable year. Therefore, the performance units are not considered granted for accounting purposes until the Compensation Committee has set the performance measure for each tranche of awards. Performance units are equity-classified awards measured at the grant date fair value. In addition, since the performance units granted do not receive DERs, the grant date fair value of these awards is reduced by the per unit distributions expected to be paid to common unitholders during the vesting period. We record compensation expense ratably for each vesting tranche over its requisite service period (one year) if it is probable that the specified performance measure will be achieved. Additionally, changes in the actual or estimated outcomes that affect the quantity of performance units expected to be converted are recognized as a cumulative adjustment.

For the period from the Employee Transfer date to December 31, 2016, no performance units vested or were granted or forfeited. For the year ended December 31, 2017, we issued 33,438 common units in connection with the performance award vestings related to 2016 performance, net of employee tax withholding requirements, and the total fair value of performance awards vested was $2.9 million. For the year ended December 31, 2018, no performance units vested with respect to 2017 performance.

A summary of our performance units is shown below:



			Granted for Accounting Purposes
	Total Performance Units Awarded		Performance Units		Weighted-Average Grant Date Fair Value per Unit
Outstanding as of January 1, 2017	77,014		35,373		$	31.75
Granted	39,320		38,865		50.04
Additional grant upon conversion (related to 2016 performance)	17,690		17,690		31.75
Vested (related to 2016 performance)	(53,063	)	(53,063	)	31.75
Outstanding as of December 31, 2017	80,961		38,865		$	50.04
Granted	116,230		80,690		$	23.43
Vested	—		—		—
Forfeitures	(38,865	)	(38,865	)	$	50.04
Outstanding as of December 31, 2018	158,326		80,690		23.43

Unit Awards

Unit awards are equity-classified awards of fully vested common units. We record compensation expense based on the fair value of the common units at the grant date. For the year ended December 31, 2018, we granted 55,133 unit awards at a grant date fair value of $24.63 per unit, resulting in the issuance of 35,745 common units, net of employee tax withholding requirements.

INCOME TAXES

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

INCOME TAXES

Components of income tax expense related to certain of our continuing operations conducted through separate taxable wholly owned corporate subsidiaries were as follows:



	Year Ended December 31,
	2018		2017			2016
	(Thousands of Dollars)
Current:
U.S.	$	4,515	$	3,117		$	2,280
Foreign	4,658		6,335			6,329
Foreign withholding tax	192		479			3,833
Total current	9,365		9,931			12,442

Deferred:
U.S.	1,403		1,468			2,680
Foreign	394		(1,065		)	(1,122		)
Foreign withholding tax	246		(397		)	(2,027		)
Total deferred	2,043		6			(469		)

Total income tax expense	$	11,408	$	9,937		$	11,973

The difference between income tax expense recorded in our consolidated statements of income and income taxes computed by applying the statutory federal income tax rate (21% for 2018 and 35% for 2017 and 2016) to income before income tax expense is due to the fact that the majority of our income is not subject to federal income tax due to our status as a limited partnership. We record a tax provision related to the amount of undistributed earnings of our foreign subsidiaries expected to be repatriated.

The tax effects of significant temporary differences representing deferred income tax assets and liabilities were as follows:



	December 31,
	2018			2017
	(Thousands of Dollars)
Deferred income tax assets:
Net operating losses	$	21,009		$	20,688
Employee benefits	362			483
Environmental and legal reserves	239			185
Allowance for bad debt	1,970			1,982
Other	1,796			2,050
Total deferred income tax assets	25,376			25,388
Less: Valuation allowance	(12,442		)	(11,251		)
Net deferred income tax assets	12,934			14,137

Deferred income tax liabilities:
Property, plant and equipment	(25,128		)	(36,176		)
Foreign withholding tax	(234		)	—
Total deferred income tax liabilities	(25,362		)	(36,176		)

Net deferred income tax liability	$	(12,428	)	$	(22,039	)

Reported on the consolidated balance sheets as:
Deferred income tax asset	$	—		$	233
Deferred income tax liability	(12,428		)	(22,272		)
Net deferred income tax liability	$	(12,428	)	$	(22,039	)

As of December 31, 2018, our U.S. and foreign corporate operations have net operating loss carryforwards for tax purposes totaling $86.8 million and $9.3 million, respectively, which are subject to various limitations on use and expire in years 2025 through 2037 for U.S. losses and in years 2019 through 2028 for foreign losses, except U.S. losses generated in 2018 can be carried forward indefinitely.

As of December 31, 2018 and 2017, we recorded a valuation allowance of $12.4 million and $11.3 million, respectively, related to our deferred tax assets. We estimate the amount of valuation allowance based upon our expectations of taxable income in the various jurisdictions in which we operate and the period over which we can utilize those future deductions. The valuation allowance reflects uncertainties related to our ability to utilize certain net operating loss carryforwards before they expire. In 2018, there was a $0.9 million increase in the valuation allowance for the U.S. net operating loss and a $0.2 million increase in the foreign net operating loss valuation allowance due to changes in our estimates of the amount of those loss carryforwards that will be realized, based upon future taxable income.

The realization of net deferred income tax assets recorded as of December 31, 2018 is dependent upon our ability to generate future taxable income in the United States. We believe it is more likely than not that the net deferred income tax assets as of December 31, 2018 will be realized, based on expected future taxable income.

Tax Reform Update

On December 22, 2017, the U.S. enacted the Act, commonly referred to as “U.S. tax reform.” The Act significantly changed U.S. corporate income tax laws by, among other things, reducing the U.S. corporate tax rate from 35% to 21%, starting in 2018, and creating a territorial tax system with a one-time mandatory tax on previously deferred foreign earnings of U.S. subsidiaries. As a result, we recorded an expense of $0.8 million in 2017 and a benefit of $0.3 million in 2018. The 2017 expense of $0.8 million, which is included in “Income tax expense” on the consolidated statements of income, consists of two components: (i) $0.7 million relating to the one-time mandatory tax on previously deferred earnings of certain non-U.S. subsidiaries that are wholly owned by one of our U.S. subsidiaries and (ii) $0.1 million resulting from the revaluation of our net deferred tax assets in the U.S. based on the new lower corporate income tax rate.

Although the $0.8 million expense represented what we believed to be a reasonable estimate of the impact of the income tax effects of the Act on our consolidated financial statements as of December 31, 2017, it was provisional. In the fourth quarter of 2018, we finalized our assessment of the two components comprising the 2017 provisional expense and recognized a benefit of $0.3 million in “Income tax expense” on the consolidated statements of income relating to the one-time mandatory tax on previously deferred earnings of certain non-U.S. subsidiaries that are wholly owned by one of our U.S. subsidiaries. No other adjustments to the provisional amounts were deemed necessary.

Due to the complexity of the new Global Intangible Low-Tax Income (GILTI) tax rules, in 2018 we continued to evaluate this provision of the Act and the application of FASB’s Accounting Standards Codification 740. Under GAAP, we are allowed to make an accounting policy choice of either (i) treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the period cost method) or (ii) factoring such amounts into a company’s measurement of its deferred taxes (the deferred method). Our selection of an accounting policy with respect to the new GILTI tax rules are based, in part, on our analysis of our global income to determine whether we expect to have future U.S. inclusions in taxable income related to GILTI and, if so, what the impact is expected to be. We will treat the taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the period cost method). The income tax effect of GILTI, reported as a component of “Income tax expense” on the consolidated statements of income for the year ended December 31, 2018, is $0.1 million.

Under GAAP, the Base Erosion Anti-Abuse Tax (BEAT) provisions are designed to be an “incremental tax,” so BEAT is treated as a current-period expense when incurred (the period cost method). We have determined that no adjustments related to BEAT are necessary in our consolidated financial statements.

SEGMENT INFORMATION

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

SEGMENT INFORMATION

Our reportable business segments consist of the pipeline, storage and fuels marketing segments. Our segments represent strategic business units that offer different services and products. We evaluate the performance of each segment based on its respective operating income, before general and administrative expenses and certain non-segmental depreciation and amortization expense. General and administrative expenses are not allocated to the operating segments since those expenses relate primarily to the overall management at the entity level. Our operations include the transportation of petroleum products and anhydrous ammonia, and the terminalling, storage and marketing of petroleum products. Intersegment revenues result from storage agreements with wholly owned subsidiaries of NuStar Energy at rates consistent with the rates charged to third parties for storage.

Results of operations for the reportable segments were as follows:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Revenues:
Pipeline	$	611,065		$	516,288		$	485,650
Storage:
Third parties	598,380			604,847			589,098
Intersegment	7,570			12,106			20,944
Total storage	605,950			616,953			610,042
Fuels marketing	752,312			692,884			681,934
Consolidation and intersegment eliminations	(7,570		)	(12,106		)	(20,944		)
Total revenues	$	1,961,757		$	1,814,019		$	1,756,682

Depreciation and amortization expense:
Pipeline	$	153,943		$	128,061		$	89,554
Storage	135,056			127,473			118,663
Total segment depreciation and amortization expense	288,999			255,534			208,217
Other depreciation and amortization expense	8,875			8,698			8,519
Total depreciation and amortization expense	$	297,874		$	264,232		$	216,736

Operating income:
Pipeline	$	272,695		$	231,795		$	248,238
Storage	181,471			219,439			214,801
Fuels marketing	24,440			5,983			3,406
Consolidation and intersegment eliminations	32			(1		)	—
Total segment operating income	478,638			457,216			466,445
General and administrative expenses	106,200			112,240			98,817
Other depreciation and amortization expense	8,875			8,698			8,519
Total operating income	$	363,563		$	336,278		$	359,109

Revenues by geographic area are shown in the table below:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars)
United States	$	1,481,863	$	1,406,626	$	1,352,936
Netherlands	398,382		322,251		313,395
Other	81,512		85,142		90,351
Consolidated revenues	$	1,961,757	$	1,814,019	$	1,756,682

For the years ended December 31, 2018, 2017 and 2016, Valero Energy Corporation accounted for approximately 16%, or $309.8 million, 17%, or $300.0 million, and 18%, or $310.0 million, of our consolidated revenues, respectively. These revenues were included in all of our reportable business segments. No other single customer accounted for 10% or more of our consolidated revenues.

Total amounts of property, plant and equipment, net by geographic area were as follows:



	December 31,
	2018		2017
	(Thousands of Dollars)
United States	$	3,687,910	$	3,519,965
Netherlands	514,541		572,817
Other	86,171		208,151
Consolidated long-lived assets	$	4,288,622	$	4,300,933

Total assets by reportable segment were as follows:



	December 31,
	2018		2017
	(Thousands of Dollars)
Pipeline	$	3,637,226	$	3,492,417
Storage	2,424,342		2,735,563
Fuels marketing	112,906		118,746
Total segment assets	6,174,474		6,346,726
Other partnership assets	174,666		188,507
Total consolidated assets	$	6,349,140	$	6,535,233

Capital expenditures, including acquisitions, by reportable segment were as follows:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars)
Pipeline	$	288,035	$	1,596,311	$	88,373
Storage	202,782		244,398		206,641
Other partnership assets	4,137		5,648		5,001
Total capital expenditures	$	494,954	$	1,846,357	$	300,015

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS

12 Months Ended

Dec. 31, 2018

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS [Abstract]

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS

NuStar Energy has no operations, and its assets consist mainly of its 100% indirectly owned subsidiaries, NuStar Logistics and NuPOP. The senior and subordinated notes issued by NuStar Logistics are fully and unconditionally guaranteed by NuStar Energy and NuPOP. As a result, the following condensed consolidating financial statements are presented as an alternative to providing separate financial statements for NuStar Logistics and NuPOP.

Condensed Consolidating Balance Sheets

December 31, 2018

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics		NuPOP		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets
Cash and cash equivalents	$	1,255	$	51	$	—	$	12,338	$	—		$	13,644
Receivables, net	—		2,212		—		146,096		—			148,308
Inventories	—		1,741		5,237		15,735		—			22,713
Prepaid and other current assets	61		14,422		908		2,102		—			17,493
Intercompany receivable	—		1,327,833		—		500,583		(1,828,416		)	—
Total current assets	1,316		1,346,259		6,145		676,854		(1,828,416		)	202,158
Property, plant and equipment, net	—		1,858,264		615,549		1,814,809		—			4,288,622
Intangible assets, net	—		49,107		—		683,949		—			733,056
Goodwill	—		149,453		170,652		716,871		—			1,036,976
Investment in wholly owned subsidiaries	3,355,636		1,750,256		1,425,283		857,485		(7,388,660		)	—
Other long-term assets, net	304		54,429		26,716		6,879		—			88,328
Total assets	$	3,357,256	$	5,207,768	$	2,244,345	$	4,756,847	$	(9,217,076	)	$	6,349,140
Liabilities, Mezzanine Equity and Partners’ Equity
Accounts payable	$	6,460	$	39,680	$	6,331	$	90,650	$	—		$	143,121
Short-term debt	—		18,500		—		—		—			18,500
Accrued interest payable	—		36,253		—		40		—			36,293
Accrued liabilities	1,280		24,858		8,082		67,773		—			101,993
Taxes other than income tax	125		7,285		4,718		6,955		—			19,083
Income tax payable	—		457		2		3,986		—			4,445
Intercompany payable	472,790		—		1,355,626		—		(1,828,416		)	—
Total current liabilities	480,655		127,033		1,374,759		169,404		(1,828,416		)	323,435
Long-term debt	—		3,050,531		—		61,465		—			3,111,996
Deferred income tax liability	—		1,675		9		10,744		—			12,428
Other long-term liabilities	—		28,392		12,348		38,818		—			79,558
Series D preferred units	563,992		—		—		—		—			563,992
Total partners’ equity	2,312,609		2,000,137		857,229		4,476,416		(7,388,660		)	2,257,731
Total liabilities, mezzanine equity and partners’ equity	$	3,357,256	$	5,207,768	$	2,244,345	$	4,756,847	$	(9,217,076	)	$	6,349,140

Condensed Consolidating Balance Sheets

December 31, 2017

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics		NuPOP		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets
Cash and cash equivalents	$	885	$	29	$	—	$	23,378	$	—		$	24,292
Receivables, net	—		280		—		176,495		—			176,775
Inventories	—		1,686		8,611		16,560		—			26,857
Prepaid and other current assets	61		11,412		4,191		6,844		—			22,508
Intercompany receivable	—		3,112,164		—		—		(3,112,164		)	—
Total current assets	946		3,125,571		12,802		223,277		(3,112,164		)	250,432
Property, plant and equipment, net	—		1,893,720		591,070		1,816,143		—			4,300,933
Intangible assets, net	—		58,530		—		725,949		—			784,479
Goodwill	—		149,453		170,652		777,370		—			1,097,475
Investment in wholly owned subsidiaries	2,891,371		24,162		1,301,717		790,882		(5,008,132		)	—
Deferred income tax asset	—		—		—		233		—			233
Other long-term assets, net	303		65,684		27,493		8,201		—			101,681
Total assets	$	2,892,620	$	5,317,120	$	2,103,734	$	4,342,055	$	(8,120,296	)	$	6,535,233
Liabilities and Partners’ Equity
Accounts payable	$	4,078	$	27,642	$	13,160	$	101,052	$	—		$	145,932
Short-term debt	—		35,000		—		—		—			35,000
Current portion of long-term debt	—		349,990		—		—		—			349,990
Accrued interest payable	—		40,402		—		47		—			40,449
Accrued liabilities	1,105		17,628		9,450		33,395		—			61,578
Taxes other than income tax	125		7,110		3,794		3,356		—			14,385
Income tax payable	—		732		4		3,436		—			4,172
Intercompany payable	322,296		—		1,277,691		1,512,177		(3,112,164		)	—
Total current liabilities	327,604		478,504		1,304,099		1,653,463		(3,112,164		)	651,506
Long-term debt, less current portion	—		3,201,220		—		61,849		—			3,263,069
Deferred income tax liability	—		1,262		12		20,998		—			22,272
Other long-term liabilities	—		58,806		8,861		50,630		—			118,297
Total partners’ equity	2,565,016		1,577,328		790,762		2,555,115		(5,008,132		)	2,480,089
Total liabilities and partners’ equity	$	2,892,620	$	5,317,120	$	2,103,734	$	4,342,055	$	(8,120,296	)	$	6,535,233

Condensed Consolidating Statements of Income (Loss)

For the Year Ended December 31, 2018

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Revenues	$	—		$	485,603		$	260,679		$	1,216,180	$	(705	)	$	1,961,757
Costs and expenses	2,407			317,286			163,667			1,115,539		(705		)	1,598,194
Operating (loss) income	(2,407		)	168,317			97,012			100,641		—			363,563
Equity in earnings of subsidiaries	207,973			17,167			121,913			212,249		(559,302		)	—
Interest income (expense), net	228			(191,835		)	(7,127		)	12,497		—			(186,237		)
Other income, net	—			3,876			446			35,554		—			39,876
Income (loss) before income tax expense (benefit)	205,794			(2,475		)	212,244			360,941		(559,302		)	217,202
Income tax expense (benefit)	—			588			(3		)	10,823		—			11,408
Net income (loss)	$	205,794		$	(3,063	)	$	212,247		$	350,118	$	(559,302	)	$	205,794

Condensed Consolidating Statements of Income (Loss)

For the Year Ended December 31, 2017

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues	$	—		$	496,454		$	221,125		$	1,097,458		$	(1,018	)	$	1,814,019
Costs and expenses	1,868			317,871			146,243			1,012,777			(1,018		)	1,477,741
Operating (loss) income	(1,868		)	178,583			74,882			84,681			—			336,278
Equity in earnings (loss) of subsidiaries	149,775			(10,616		)	89,405			158,700			(387,264		)	—
Interest income (expense), net	57			(176,897		)	(5,587		)	9,344			—			(173,083		)
Other income (expense), net	—			145			3			(5,442		)	—			(5,294		)
Income (loss) before income tax (benefit) expense	147,964			(8,785		)	158,703			247,283			(387,264		)	157,901
Income tax (benefit) expense	—			(820		)	2			10,755			—			9,937
Net income (loss)	$	147,964		$	(7,965	)	$	158,701		$	236,528		$	(387,264	)	$	147,964

Condensed Consolidating Statements of Income (Loss)

For the Year Ended December 31, 2016

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues	$	—		$	511,650		$	224,966		$	1,021,804		$	(1,738	)	$	1,756,682
Costs and expenses	1,806			302,099			150,384			945,022			(1,738		)	1,397,573
Operating (loss) income	(1,806		)	209,551			74,582			76,782			—			359,109
Equity in earnings (loss) of subsidiaries	151,794			(13,769		)	82,202			156,036			(376,263		)	—
Interest (expense) income, net	—			(139,827		)	(744		)	2,221			—			(138,350		)
Other income (expense), net	18			(58,264		)	(26		)	(511		)	—			(58,783		)
Income (loss) before income tax expense (benefit)	150,006			(2,309		)	156,014			234,528			(376,263		)	161,976
Income tax expense (benefit)	3			1,607			(23		)	10,386			—			11,973
Net income (loss)	$	150,003		$	(3,916	)	$	156,037		$	224,142		$	(376,263	)	$	150,003

Condensed Consolidating Statements of Comprehensive Income

For the Year Ended December 31, 2018

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics			NuPOP		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Net income (loss)	$	205,794	$	(3,063	)	$	212,247	$	350,118	$	(559,302	)	$	205,794

Other comprehensive income:
Foreign currency translation adjustment	—		—			—		4,304		—			4,304
Net gain on pension and other postretirement benefit adjustments, net of tax expense	—		—			—		2,334		—			2,334
Net gain on cash flow hedges	—		23,411			—		—		—			23,411
Total other comprehensive income	—		23,411			—		6,638		—			30,049
Comprehensive income	$	205,794	$	20,348		$	212,247	$	356,756	$	(559,302	)	$	235,843

Condensed Consolidating Statements of Comprehensive Income (Loss)

For the Year Ended December 31, 2017

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics			NuPOP		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	147,964	$	(7,965	)	$	158,701	$	236,528		$	(387,264	)	$	147,964

Other comprehensive income (loss):
Foreign currency translation adjustment	—		—			—		17,466			—			17,466
Net loss on pension and other postretirement benefit adjustments, net of tax benefit	—		—			—		(6,170		)	—			(6,170		)
Net loss on cash flow hedges	—		(2,046		)	—		—			—			(2,046		)
Total other comprehensive (loss) income	—		(2,046		)	—		11,296			—			9,250
Comprehensive income (loss)	$	147,964	$	(10,011	)	$	158,701	$	247,824		$	(387,264	)	$	157,214

Condensed Consolidating Statements of Comprehensive Income

For the Year Ended December 31, 2016

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics			NuPOP		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	150,003	$	(3,916	)	$	156,037	$	224,142		$	(376,263	)	$	150,003

Other comprehensive income (loss):
Foreign currency translation adjustment	—		—			—		(8,243		)	—			(8,243		)
Net loss on pension and other postretirement benefit adjustments, net of tax benefit	—		—			—		(2,850		)	—			(2,850		)
Net gain on cash flow hedges	—		5,710			—		—			—			5,710
Total other comprehensive income (loss)	—		5,710			—		(11,093		)	—			(5,383		)
Comprehensive income	$	150,003	$	1,794		$	156,037	$	213,049		$	(376,263	)	$	144,620

Condensed Consolidating Statements of Cash Flows

For the Year Ended December 31, 2018

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided by operating activities	$	444,233		$	100,385		$	179,512		$	514,936		$	(694,859	)	$	544,207
Cash flows from investing activities:
Capital expenditures	—			(71,044		)	(19,152		)	(367,256		)	—			(457,452		)
Change in accounts payable related to capital expenditures	—			11,101			(5,161		)	(13,623		)	—			(7,683		)
Acquisitions	—			—			(37,502		)	—			—			(37,502		)
Proceeds from insurance recoveries	—			—			—			78,419			—			78,419
Proceeds from sale of European operations	—			—			—			266,740			—			266,740
Proceeds from sale or disposition of assets	—			2,674			31			995			—			3,700
Investment in subsidiaries	(708,600		)	(1,711,975		)	(54,600		)	(54,665		)	2,529,840			—
Net cash used in investing activities	(708,600		)	(1,769,244		)	(116,384		)	(89,390		)	2,529,840			(153,778		)
Cash flows from financing activities:
Debt borrowings	—			1,840,853			—			31,800			—			1,872,653
Debt repayments	—			(2,349,476		)	—			(32,300		)	—			(2,381,776		)
Issuance of Series D preferred units	590,000			—			—			—			—			590,000
Payment of issuance costs for Series D preferred units	(34,203		)	—			—			—			—			(34,203		)
Issuance of common units, net of issuance costs	10,000			—			—			—			—			10,000
General partner contribution	204			—			—			—			—			204
Distributions to preferred unitholders	(90,670		)	(45,336		)	(45,336		)	(45,335		)	136,007			(90,670		)
Distributions to common unitholders and general partner	(300,777		)	(150,388		)	(150,388		)	(150,408		)	451,184			(300,777		)
Cash consideration for Merger (Note 4)	(67,936		)	—			—			141			—			(67,795		)
Proceeds from termination of interest rate swaps	—			8,048			—			—			—			8,048
Contributions from affiliates	—			599,400			54,600			1,768,172			(2,422,172		)	—
Net intercompany activity	162,498			1,766,881			77,996			(2,007,375		)	—			—
Other, net	(4,379		)	(1,101		)	—			(71		)	—			(5,551		)
Net cash provided by (used in) financing activities	264,737			1,668,881			(63,128		)	(435,376		)	(1,834,981		)	(399,867		)
Effect of foreign exchange rate changes on cash	—			—			—			(1,210		)	—			(1,210		)
Net increase (decrease) in cash and cash equivalents	370			22			—			(11,040		)	—			(10,648		)
Cash and cash equivalents as of the beginning of the period	885			29			—			23,378			—			24,292
Cash and cash equivalents as of the end of the period	$	1,255		$	51		$	—		$	12,338		$	—		$	13,644

Condensed Consolidating Statements of Cash Flows

For the Year Ended December 31, 2017

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided by operating activities	$	483,481		$	152,101		$	102,405		$	405,950		$	(737,138	)	$	406,799
Cash flows from investing activities:
Capital expenditures	—			(47,600		)	(35,041		)	(301,997		)	—			(384,638		)
Change in accounts payable related to capital expenditures	—			(1,988		)	5,964			32,927			—			36,903
Acquisitions	—			—			—			(1,461,719		)	—			(1,461,719		)
Proceeds from Axeon term loan	—			110,000			—			—			—			110,000
Proceeds from insurance recoveries	—			—			—			977			—			977
Proceeds from sale or disposition of assets	—			1,955			18			63			—			2,036
Investment in subsidiaries	(1,262,000		)	—			—			(126		)	1,262,126			—
Net cash (used in) provided by investing activities	(1,262,000		)	62,367			(29,059		)	(1,729,875		)	1,262,126			(1,696,441		)
Cash flows from financing activities:
Debt borrowings	—			2,969,400			—			90,700			—			3,060,100
Debt repayments	—			(2,400,739		)	—			(86,800		)	—			(2,487,539		)
Issuance of preferred units, net of issuance costs	538,560			—			—			—			—			538,560
Issuance of common units, net of issuance costs	643,878			—			—			—			—			643,878
General partner contribution	13,737			—			—			—			—			13,737
Distributions to preferred unitholders	(38,833		)	(19,417		)	(19,416		)	(19,418		)	58,251			(38,833		)
Distributions to common unitholders and general partner	(446,306		)	(223,153		)	(223,153		)	(223,176		)	669,482			(446,306		)
Contributions from (distributions to) affiliates	—			1,262,000			—			(9,279		)	(1,252,721		)	—
Net intercompany activity	73,206			(1,801,218		)	169,223			1,558,789			—			—
Other, net	(5,708		)	(1,317		)	—			(300		)	—			(7,325		)
Net cash provided by (used in) financing activities	778,534			(214,444		)	(73,346		)	1,310,516			(524,988		)	1,276,272
Effect of foreign exchange rate changes on cash	—			—			—			1,720			—			1,720
Net increase (decrease) in cash and cash equivalents	15			24			—			(11,689		)	—			(11,650		)
Cash and cash equivalents as of the beginning of the period	870			5			—			35,067			—			35,942
Cash and cash equivalents as of the end of the period	$	885		$	29		$	—		$	23,378		$	—		$	24,292

Condensed Consolidating Statements of Cash Flows

For the Year Ended December 31, 2016

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided by operating activities	$	391,773		$	167,900		$	211,816		$	359,283		$	(694,011	)	$	436,761
Cash flows from investing activities:
Capital expenditures	—			(64,334		)	(52,637		)	(87,387		)	—			(204,358		)
Change in accounts payable related to capital expenditures	—			(10,076		)	(285		)	(702		)	—			(11,063		)
Acquisitions	—			(95,657		)	—			—			—			(95,657		)
Investment in subsidiaries	—			—			(212,900		)	—			212,900			—
Net cash used in investing activities	—			(170,067		)	(265,822		)	(88,089		)	212,900			(311,078		)
Cash flows from financing activities:
Debt borrowings	—			1,365,529			—			41,200			—			1,406,729
Debt repayments	—			(1,419,852		)	—			(36,300		)	—			(1,456,152		)
Issuance of preferred units, net of issuance costs	218,400			—			—			—			—			218,400
Issuance of common units, net of issuance costs	27,710			—			—			—			—			27,710
General partner contribution	680			—			—			—			—			680
Distributions to common unitholders and general partner	(392,962		)	(196,481		)	(196,481		)	(196,501		)	589,463			(392,962		)
Contributions from affiliates	—			—			—			108,352			(108,352		)	—
Net intercompany activity	(241,131		)	255,326			250,487			(264,682		)	—			—
Other, net	(4,485		)	(2,354		)	—			(8,890		)	—			(15,729		)
Net cash (used in) provided by financing activities	(391,788		)	2,168			54,006			(356,821		)	481,111			(211,324		)
Effect of foreign exchange rate changes on cash	—			—			—			2,721			—			2,721
Net (decrease) increase in cash and cash equivalents	(15		)	1			—			(82,906		)	—			(82,920		)
Cash and cash equivalents as of the beginning of the period	885			4			—			117,973			—			118,862
Cash and cash equivalents as of the end of the period	$	870		$	5		$	—		$	35,067		$	—		$	35,942

QUARTERLY FINANCIAL DATA (UNAUDITED)

12 Months Ended

Dec. 31, 2018

Selected Quarterly Financial Information [Abstract]

QUARTERLY FINANCIAL DATA (UNAUDITED)

The following table summarizes quarterly financial data for the years ended December 31, 2018 and 2017:



	First Quarter		Second Quarter		Third Quarter			Fourth Quarter			Total
	(Thousands of Dollars, Except Per Unit Data)
2018:
Revenues	$	475,881	$	486,204	$	490,363		$	509,309		$	1,961,757
Operating income	$	98,480	$	79,838	$	95,277		$	89,968		$	363,563
Net income	$	126,133	$	29,399	$	48,136		$	2,126		$	205,794
Basic and diluted net income (loss) per common unit	$	1.15	$	0.15	$	(3.49	)	$	(0.31	)	$	(2.77	)
Cash distributions per unit applicable to common limited partners	$	0.60	$	0.60	$	0.60		$	0.60		$	2.40

2017:
Revenues	$	487,430	$	435,488	$	440,566		$	450,535		$	1,814,019
Operating income	$	97,139	$	73,404	$	91,717		$	74,018		$	336,278
Net income	$	57,940	$	26,250	$	38,592		$	25,182		$	147,964
Basic and diluted net income per common unit	$	0.49	$	0.05	$	0.15		$	0.00		$	0.64
Cash distributions per unit applicable to common limited partners	$	1.095	$	1.095	$	1.095		$	1.095		$	4.380

The quarterly financial data in the table above includes the impact of the $78.8 million gain from hurricane insurance proceeds received in the first quarter of 2018 and the $43.4 million non-cash loss associated with the sale of our European operations in the fourth quarter of 2018. Please refer to Note 1 for further discussion of the hurricane insurance proceeds and Note 5 for further discussion of the sale of our European operations.

Basic and diluted net income (loss) per common unit also includes the impact of the $377.1 million loss as a result of the Merger. Please refer to Notes 4 and 21 for further discussion.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Consolidation

Use of Estimates

Cash and Cash Equivalents

Cash equivalents are all highly liquid investments with an original maturity of three months or less when acquired.

Accounts Receivable

Inventories

Property, Plant and Equipment

Goodwill

Our reporting units to which goodwill has been allocated consist of the following:


•	crude oil pipelines;


•	refined product pipelines;


•	terminals, excluding our St. Eustatius and Point Tupper facilities and our refinery crude storage tanks; and


•	bunkering activity at our St. Eustatius and Point Tupper facilities.

Impairment of Long-Lived Assets

Income Taxes

Asset Retirement Obligations

Environmental Remediation Costs

Product Imbalances

Revenue Recognition

Revenues for the fuels marketing segment are derived from the sale of petroleum products.

Income Allocation

Basic and Diluted Net Income per Common Unit

Basic and Diluted Net (Loss) Income Per Common Unit

Derivative Financial Instruments

Unit-based Compensation

Margin Deposits

Foreign Currency Translation

MERGER AND RELATED PARTY AGREEMENTS (Tables)

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Calculation of Gain or Loss Attributable to Merger [Table Text Block]

The excess of (1) the fair value of the consideration transferred in exchange for the outstanding NSH units over (2) the carrying value of the general partner interest in the Partnership was subtracted from net income available to common unitholders in the calculation of net loss per common unit attributable to the Merger as follows (in thousands of dollars, except unit and per unit data):



Consideration transferred:
Fair value of incremental NS common units issued	$	335,106
NSH debt and assumed net current liabilities	52,075
Transaction costs	15,897
Total consideration	403,078

Carrying value of general partner interest	25,999
Loss to common unitholders attributable to the Merger	$	(377,079	)

For the year ended December 31, 2018:
Basic weighted-average common units outstanding	99,490,495
Loss per common unit attributable to the Merger	$	(3.79	)

DISPOSITION AND ACQUISITIONS (Tables)

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]

The following table reflects the final purchase price allocation:



	Purchase Price Allocation
	(Thousands of Dollars)
Accounts receivable	$	4,747
Other current assets	2,359
Property, plant and equipment, net	376,690
Intangible assets (a)	700,000
Goodwill (b)	398,024
Other long-term assets, net	2,199
Current liabilities	(22,300		)
Purchase price allocation, net of cash acquired	$	1,461,719


(a)	Intangible assets, which consist of customer contracts and relationships, are amortized on a straight-line basis over a period of 20 years.


(b)	The goodwill acquired represents the expected benefit from entering new geographic areas and the anticipated opportunities to generate future cash flows from the assets acquired and potential future projects.

Business Acquisition, Pro Forma Information [Table Text Block]


•	we completed the Navigator Acquisition on January 1, 2016;


•	we issued approximately 14.4 million common units;


•	we received a contribution from our general partner of $13.6 million to maintain the 2% general partner economic interest it owned at that time;


•	we issued 15.4 million Series B Preferred Units;


•	we issued $550.0 million of 5.625% senior notes;


•	additional depreciation and amortization that would have been incurred assuming the fair value adjustments to property, plant and equipment and intangible assets reflected in the purchase price allocation above; and


•	we satisfied Navigator’s outstanding obligations under its revolving credit agreement.



	Year Ended December 31,
	2017		2016
	(Thousands of Dollars, Except Per Unit Data)
Revenues	$	1,828,418	$	1,782,932
Net income	$	127,433	$	78,664

Basic and diluted net income per common unit	$	0.31	$	0.01

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Schedule of Adoption of New Accounting Pronouncements [Table Text Block]

The adoption of ASC Topic 606 affected our consolidated statements of comprehensive income as follows:



	As Reported			Without Adoption of ASC Topic 606			Effect of Change Higher/(Lower)
	(Thousands of Dollars, Except Per Unit Data)
For the year ended December 31, 2018:
Revenues	$	1,961,757		$	1,967,942		$	(6,185	)
Operating income	$	363,563		$	369,748		$	(6,185	)
Net income	$	205,794		$	211,979		$	(6,185	)
Basic net loss per common unit	$	(2.77	)	$	(2.70	)	$	(0.07	)

Contract with Customer, Asset and Liability [Table Text Block]

The following table provides information about contract assets and contract liabilities from contracts with customers:



	Contract Assets			Contract Liabilities
	(Thousands of Dollars)
Balance as of January 1, 2018	$	2,127		$	(60,464	)

Additions	3,281			(83,243		)
Transfer to accounts receivable	(2,803		)	—
Transfer to revenues	—			57,826
Total activity	478			(25,417		)


Balance as of December 31, 2018	2,605			(85,881		)
Less current portion	2,066			(46,936		)
Noncurrent portion	$	539		$	(38,945	)

Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]



2019	$	473,027
2020	383,889
2021	261,900
2022	210,772
2023	162,952
Thereafter	361,153
Total	$	1,853,693

Disaggregation of Revenue [Table Text Block]

The following table disaggregates our revenues:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Pipeline segment:
Crude oil pipelines (excluding lessor revenues)	$	248,261		$	187,874		$	154,543
Refined products and ammonia pipelines	362,750			328,414			331,107
Total pipeline segment revenues from contracts with customers	611,011			516,288			485,650
Lessor revenues	54			—			—
Total pipeline segment revenues	611,065			516,288			485,650

Storage segment:
Throughput terminals	83,157			85,927			117,586
Storage terminals (excluding lessor revenues)	482,944			491,900			492,456
Total storage segment revenues from contracts with customers	566,101			577,827			610,042
Lessor revenues	39,849			39,126			—
Total storage segment revenues	605,950			616,953			610,042

Fuels marketing segment revenues from contracts with customers	752,312			692,884			681,934

Consolidation and intersegment eliminations	(7,570		)	(12,106		)	(20,944		)

Total revenues	$	1,961,757		$	1,814,019		$	1,756,682

ALLOWANCE FOR DOUBTFUL ACCOUNTS (Tables)

12 Months Ended

Dec. 31, 2018

Accounts Receivable Additional Disclosures [Abstract]

Allowance for Doubtful Accounts [Table Text Block]

The changes in the allowance for doubtful accounts consisted of the following:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Balance as of beginning of year	$	9,948		$	7,756		$	8,473
Increase in allowance, net	755			2,217			24
Accounts charged against the allowance	(1,291		)	(25		)	(741		)
Balance as of end of year	$	9,412		$	9,948		$	7,756

INVENTORIES (Tables)

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Schedule of Inventory Table [Text Block]

Inventories consisted of the following:



	December 31,
	2018		2017
	(Thousands of Dollars)
Petroleum products	$	12,689	$	17,027
Materials and supplies	10,024		9,830
Total	$	22,713	$	26,857

PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment [Table Text Block]

Property, plant and equipment consisted of the following:



	Estimated Useful Lives			December 31,
	Estimated Useful Lives			2018			2017
	(Years)			(Thousands of Dollars)
Land		-		$	143,477		$	143,527
Land and leasehold improvements	5	-	40	215,796			203,085
Buildings	15	-	40	160,069			151,702
Pipelines, storage and terminals	15	-	40	5,315,201			5,080,795
Rights-of-way	20	-	40	301,739			264,170
Construction in progress		-		202,030			400,202
Total				6,338,312			6,243,481
Less accumulated depreciation and amortization				(2,049,690		)	(1,942,548		)
Property, plant and equipment, net				$	4,288,622		$	4,300,933

INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2018

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Schedule of Finite-Lived Intangible Assets by Major Class [Table Text Block]

Intangible assets consisted of the following:



		December 31, 2018					December 31, 2017
	Weighted-Average Amortization Period	Cost		Accumulated Amortization			Cost		Accumulated Amortization
	(Years)	(Thousands of Dollars)
Customer contracts and relationships	18	$	863,950	$	(132,509	)	$	863,950	$	(81,136	)
Other	47	2,359		(744		)	2,359		(694		)
Total		$	866,309	$	(133,253	)	$	866,309	$	(81,830	)

GOODWILL (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill [Table Text Block]

Changes in the carrying amount of goodwill by segment were as follows:



	Pipeline			Storage			Fuels Marketing		Total
	(Thousands of Dollars)
Balances as of January 1, 2017:
Goodwill	$	306,207		$	663,760		$	31,123	$	1,001,090
Accumulated impairment losses	—			(304,453		)	—		(304,453		)
Net goodwill	306,207			359,307			31,123		696,637

Activity for the year ended December 31, 2017:
Navigator Acquisition preliminary purchase price allocation (a)	400,838			—			—		400,838

Balances as of December 31, 2017:
Goodwill	707,045			663,760			31,123		1,401,928
Accumulated impairment losses	—			(304,453		)	—		(304,453		)
Net goodwill	707,045			359,307			31,123		1,097,475

Activity for the year ended December 31, 2018:
Navigator Acquisition purchase price allocation adjustments (a)	(2,814		)	—			—		(2,814		)
Adjustment due to the sale of our European operations (a)	—			(57,685		)	—		(57,685		)

Balances as of December 31, 2018:
Goodwill	704,231			606,075			31,123		1,341,429
Accumulated impairment losses	—			(304,453		)	—		(304,453		)
Net goodwill	$	704,231		$	301,622		$	31,123	$	1,036,976


(a)	See Note 5 for discussion of the Navigator Acquisition and the sale of our European operations.

ACCRUED LIABILITIES (Tables)

12 Months Ended

Dec. 31, 2018

Accrued Liabilities, Current [Abstract]

Schedule of Accrued Liabilities [Table Text Block]

Accrued liabilities consisted of the following:



	December 31,
	2018		2017
	(Thousands of Dollars)
Employee wages and benefit costs	$	30,720	$	16,963
Revenue contract liabilities	46,936		—
Deferred revenue	—		18,243
Other	24,337		26,372
Accrued liabilities	$	101,993	$	61,578

DEBT (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]

Long-term debt consisted of the following:



				December 31,
	Maturity			2018			2017
				(Thousands of Dollars)
Revolving Credit Agreement		2020		$	745,000		$	893,311
7.65% senior notes		2018		—			350,000
4.80% senior notes		2020		450,000			450,000
6.75% senior notes		2021		300,000			300,000
4.75% senior notes		2022		250,000			250,000
5.625% senior notes		2027		550,000			550,000
Subordinated Notes		2043		402,500			402,500
GoZone Bonds	2038	thru	2041	365,440			365,440
Receivables Financing Agreement		2020		61,800			62,300
Net fair value adjustments, unamortized discounts and unamortized debt issuance costs		N/A		(12,744		)	(10,492		)
Total long-term debt				3,111,996			3,613,059
Less current portion				—			349,990
Long-term debt, less current portion				$	3,111,996		$	3,263,069

Schedule of Maturities of Long-term Debt [Table Text Block]

The long-term debt repayments are due as follows (in thousands of dollars):



2019	$	—
2020	1,256,800
2021	300,000
2022	250,000
2023	—
Thereafter	1,317,940
Total repayments	3,124,740
Net fair value adjustments, unamortized discounts and unamortized debt issuance costs	(12,744		)
Total long-term debt	$	3,111,996

Schedule of GoZone Bonds [Table Text Block]

The following table summarizes the GoZone Bonds outstanding as of December 31, 2018:



Date Issued	Maturity Date	Amount Outstanding		Amount of Letter of Credit		Amount Received from Trustee		Amount Remaining in Trust (a)		Interest Rate (b)
		(Thousands of Dollars)
June 26, 2008	June 1, 2038	$	55,440	$	56,169	$	55,440	$	—	1.8	%
July 15, 2010	July 1, 2040	100,000		101,315		100,000		—		1.8	%
October 7, 2010	October 1, 2040	50,000		50,658		43,741		6,596		1.8	%
December 29, 2010	December 1, 2040	85,000		86,118		49,782		36,271		1.8	%
August 29, 2011	August 1, 2041	75,000		75,986		75,000		—		1.8	%
	Total	$	365,440	$	370,246	$	323,963	$	42,867


(a)	Amount remaining in trust includes accrued interest.


(b)	For the year ended December 31, 2018, our weighted-average interest rate on borrowings was 1.4%.

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

HEALTH, SAFETY AND ENVIRONMENTAL MATTERS (Tables)

12 Months Ended

Dec. 31, 2018

Environmental Remediation Obligations [Abstract]

Schedule of Environmental Accrual Rollforward [Table Text Block]

The balance of and changes in the accruals for environmental matters were as follows:



	Year Ended December 31,
	2018			2017
	(Thousands of Dollars)
Balance as of the beginning of year	$	5,683		$	5,120
Additions to accrual	5,160			3,186
Payments	(3,058		)	(2,675		)
Foreign currency translation	(32		)	52
Balance as of the end of year	$	7,753		$	5,683

Environmental Accruals By Balance Sheet Location [Table Text Block]

Accruals for environmental matters are included in the consolidated balance sheets as follows:



	December 31,
	2018		2017
	(Thousands of Dollars)
Accrued liabilities	$	4,349	$	3,054
Other long-term liabilities	3,404		2,629
Accruals for environmental matters	$	7,753	$	5,683

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments for Operating Leases and Purchase Obligations [Table Text Block]

Lessee and Other Commitments. Future minimum rental payments applicable to all noncancellable operating leases and purchase obligations as of December 31, 2018 are as follows:



	Payments Due by Period
	2019		2020		2021		2022		2023		There- after		Total
	(Thousands of Dollars)
Operating leases	$	34,900	$	20,787	$	14,904	$	9,280	$	6,870	$	28,552	$	115,293
Purchase obligations	$	10,896	$	7,958	$	7,011	$	4,970	$	602	$	2,624	$	34,061

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block]

The following assets and liabilities are measured at fair value on a recurring basis:



	December 31, 2018
	Level 1		Level 2			Level 3		Total
	(Thousands of Dollars)
Assets:
Other current assets:
Commodity derivatives	$	130	$	—		$	—	$	130
Other long-term assets, net:
Interest rate swaps	—		627			—		627
Total assets	$	130	$	627		$	—	$	757
Liabilities:
Other long-term liabilities:
Interest rate swaps	$	—	$	(751	)	$	—	$	(751	)



	December 31, 2017
	Level 1			Level 2			Level 3		Total
	(Thousands of Dollars)
Assets:
Other current assets:
Product imbalances	$	3,890		$	—		$	—	$	3,890
Liabilities:
Accrued liabilities:
Product imbalances	$	(1,534	)	$	—		$	—	$	(1,534	)
Commodity derivatives	(878		)	—			—		(878		)
Interest rate swaps	—			(5,394		)	—		(5,394		)
Other long-term liabilities:
Interest rate swaps	—			(4,594		)	—		(4,594		)
Total liabilities	$	(2,412	)	$	(9,988	)	$	—	$	(12,400	)

Fair Value and Carrying Value of Debt [Table Text Block]

The estimated fair values and carrying amounts of the long-term debt, including the current portion, were as follows:



	December 31, 2018		December 31, 2017
	(Thousands of Dollars)
Fair value	$	3,056,704	$	3,677,622
Carrying amount	$	3,111,996	$	3,613,059

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES (Tables)

12 Months Ended

Dec. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Text Block]

The fair values of our derivative instruments included in our consolidated balance sheets were as follows:



		Asset Derivatives				Liability Derivatives
	Balance Sheet Location	December 31,
	Balance Sheet Location	2018		2017		2018			2017
		(Thousands of Dollars)
Derivatives Designated as Hedging Instruments:
Commodity contracts	Other current assets	$	109	$	—	$	—		$	—
Interest rate swaps	Other long-term assets, net	627		—		—			—
Commodity contracts	Accrued liabilities	—		—		—			(112		)
Interest rate swaps	Accrued liabilities	—		—		—			(5,394		)
Interest rate swaps	Other long-term liabilities	—		—		(751		)	(4,594		)
Total		736		—		(751		)	(10,100		)

Derivatives Not Designated as Hedging Instruments:
Commodity contracts	Other current assets	1,652		—		(1,631		)	—
Commodity contracts	Accrued liabilities	—		742		—			(1,508		)
Total		1,652		742		(1,631		)	(1,508		)

Total Derivatives		$	2,388	$	742	$	(2,382	)	$	(11,608	)

Offsetting Assets [Table Text Block]

The following are the net amounts presented on the consolidated balance sheets:



	December 31,
Commodity Contracts	2018		2017
	(Thousands of Dollars)
Net amounts of assets presented in the consolidated balance sheets	$	130	$	—
Net amounts of liabilities presented in the consolidated balance sheets	$	—	$	(878	)

Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Text Block]

We recognize the impact of our commodity contracts on earnings in “Cost of product sales” on the consolidated income statements, and that impact was as follows:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Derivatives Designated as Fair Value Hedging Instruments:
(Loss) gain recognized in income on derivative	$	(535	)	$	806		$	(11,254	)
(Loss) gain recognized in income on hedged item	(181		)	(656		)	15,295
(Loss) gain recognized in income for ineffective portion	$	(716	)	$	150		$	4,041

Derivatives Not Designated as Hedging Instruments:
(Loss) gain recognized in income on derivative	$	(601	)	$	(668	)	$	225

Our interest rate swaps had the following impact on earnings:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Derivatives Designated as Cash Flow Hedging Instruments:
Gain (loss) recognized in other comprehensive income (loss) on derivative (effective portion)	$	17,912		$	(8,670	)	$	(2,621	)
Loss reclassified from AOCI into interest expense, net (effective portion)	$	(5,499	)	$	(6,624	)	$	(8,331	)

OTHER INCOME (EXPENSE) (Tables)

12 Months Ended

Dec. 31, 2018

Other Income and Expenses [Abstract]

Schedule of Other Income (Expense)

Other income (expense) consisted of the following:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Gain (loss) related to hurricane activity	$	78,756		$	(5,000	)	$	—
Impairment loss on Axeon Term Loan	—			—			(58,655		)
Loss on sale of European operations	(43,366		)	—			—
Other, net	4,486			(294		)	(128		)
Other income (expense), net	$	39,876		$	(5,294	)	$	(58,783	)

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS (Tables)

12 Months Ended

Dec. 31, 2018

Series D Preferred Limited Partner [Member]

Class of Stock [Line Items]

Distributions Made to Limited Partner, by Distribution [Table Text Block]

The following table summarizes information about cash distributions declared for our Series D Preferred Units:



Period	Cash Distributions Per Unit		Total Cash Distributions		Record Date	Payment Date
			(Thousands of Dollars)
December 15, 2018 - March 14, 2019	$	0.619	$	14,390	March 1, 2019	March 15, 2019
September 15, 2018 - December 14, 2018	$	0.619	$	14,390	December 3, 2018	December 17, 2018
July 13, 2018 - September 14, 2018 (a)	$	0.431	$	3,227	September 4, 2018	September 17, 2018
June 29, 2018 - September 14, 2018 (b)	$	0.525	$	8,274	September 4, 2018	September 17, 2018


(a)	Second issuance of 7,486,209 units.


(b)	First issuance of 15,760,441 units.

PARTNERS' EQUITY (Tables)

12 Months Ended

Dec. 31, 2018

Distributions Made to Limited Partners and General Partner [Line Items]

Schedule of Preferred Units [Table Text Block]



Units	Original Issuance Date	Number of Units Issued and Outstanding	Price per Unit		Net Proceeds (in millions)		Fixed Distribution Rate per Annum (as a Percentage of the $25.00 Liquidation Preference per Unit)		Fixed Distribution Rate per Unit per Annum		Optional Redemption Date/Date at Which Distribution Rate Becomes Floating	Floating Annual Rate (as a Percentage of the $25.00 Liquidation Preference per Unit)
Series A Preferred Units	November 25, 2016	9,060,000	$	25.00	$	218.4	8.50	%	$	2.125	December 15, 2021	Three-month LIBOR plus 6.766%
Series B Preferred Units	April 28, 2017	15,400,000	$	25.00	$	371.8	7.625	%	$	1.90625	June 15, 2022	Three-month LIBOR plus 5.643%
Series C Preferred Units	November 30, 2017	6,900,000	$	25.00	$	166.7	9.00	%	$	2.25	December 15, 2022	Three-month LIBOR plus 6.88%

The following table summarizes financial information related to our Series A, B and C Preferred Units:



	Preferred Limited Partners
	Series A			Series B			Series C			Total
	(Thousands of Dollars)
Balance as of January 1, 2016	$	—		$	—		$	—		$	—
Issuance of units	218,400			—			—			218,400
Net income	1,925			—			—			1,925
Distributions to partners	(1,925		)	—			—			(1,925		)
Balance as of December 31, 2016	218,400			—			—			218,400
Issuance of units	—			371,823			166,737			538,560
Net income	19,253			19,815			1,380			40,448
Distributions to partners	(19,253		)	(19,815		)	(1,380		)	(40,448		)
Other	(93		)	(189		)	(75		)	(357		)
Balance as of December 31, 2017	218,307			371,634			166,662			756,603
Net income	19,253			29,357			15,481			64,091
Distributions to partners	(19,253		)	(29,357		)	(15,481		)	(64,091		)
Other	—			(158		)	(144		)	(302		)
Balance as of December 31, 2018	$	218,307		$	371,476		$	166,518		$	756,301

Schedule of Calculation of Net Income Applicable to General Partner [Table Text Block]

The following table details the calculation of net income applicable to the general partner for 2017 and 2016:



	Year Ended December 31,
	2017			2016
	(Thousands of Dollars)
Net income attributable to NuStar Energy L.P.	$	147,964		$	150,003
Less preferred limited partner interest	40,448			1,925
Less general partner incentive distribution	45,669			43,407
Net income after general partner incentive distribution and preferred limited partner interest	61,847			104,671
General partner interest allocation	2		%	2		%
General partner interest allocation of net income	1,237			2,091
General partner incentive distribution	45,669			43,407
Net income applicable to general partner	$	46,906		$	45,498

Schedule of Distribution Waterfall [Table Text Block]

Prior to the Merger, our Available Cash was distributed based on the percentages shown below:



	Percentage of Distribution
Quarterly Distribution Amount Per Common Unit	Common Unitholders	General Partner Including Incentive Distributions
Up to $0.60	98%	2%
Above $0.60 up to $0.66	90%	10%
Above $0.66	75%	25%

Schedule of Distributions To General and Common Limited Partners [Table Text Block]

The following table reflects the allocation of total cash distributions to the general partner and common limited partners applicable to the period in which the distributions were earned:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars, Except Per Unit Data)
General partner interest	$	1,141	$	9,252	$	7,877
General partner incentive distribution	—		45,669		43,407
Total general partner distribution	1,141		54,921		51,284
Common limited partners’ distribution	248,705		407,681		342,598
Total cash distributions	$	249,846	$	462,602	$	393,882

Cash distributions per unit applicable to common limited partners	$	2.40	$	4.38	$	4.38

Distributions Made To Common Limited And General Partners By Distribution [Table Text Block]

The following table summarizes information about quarterly cash distributions declared for our common limited partners, and prior to the Merger, our general partner:



Quarter Ended	Cash Distributions Per Unit		Total Cash Distributions		Record Date	Payment Date
			(Thousands of Dollars)
December 31, 2018	$	0.60	$	64,336	February 8, 2019	February 13, 2019
September 30, 2018	$	0.60	$	64,248	November 8, 2018	November 14, 2018
June 30, 2018	$	0.60	$	64,205	August 7, 2018	August 13, 2018
March 31, 2018	$	0.60	$	57,057	May 8, 2018	May 14, 2018

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The balance of and changes in the components included in AOCI were as follows:



	Foreign Currency Translation			Cash Flow Hedges			Pension and Other Postretirement Benefits			Total
	(Thousands of Dollars)
Balance as of January 1, 2016	$	(60,826	)	$	(27,968	)	$	—		$	(88,794	)
Employee Transfer	—			—			4,201			4,201
Deferred income tax adjustments	—			—			2,414			2,414
Other comprehensive loss before reclassification adjustments	(8,243		)	(2,621		)	(7,852		)	(18,716		)
Net gain on pension costs reclassified into operating expense	—			—			(1,200		)	(1,200		)
Net gain on pension costs reclassified into general and administrative expense	—			—			(413		)	(413		)
Net loss on cash flow hedges reclassified into interest expense, net	—			8,331			—			8,331
Other comprehensive (loss) income	(8,243		)	5,710			(2,850		)	(5,383		)
Balance as of December 31, 2016	(69,069		)	(22,258		)	(2,850		)	(94,177		)
Other comprehensive income (loss) before reclassification adjustments	17,466			(8,670		)	(4,641		)	4,155
Net gain on pension costs reclassified into operating expense	—			—			(1,143		)	(1,143		)
Net gain on pension costs reclassified into general and administrative expense	—			—			(386		)	(386		)
Net loss on cash flow hedges reclassified into interest expense, net	—			6,624			—			6,624
Other comprehensive income (loss)	17,466			(2,046		)	(6,170		)	9,250
Balance as of December 31, 2017	(51,603		)	(24,304		)	(9,020		)	(84,927		)
Other comprehensive income before reclassification adjustments	(13,880		)	17,912			3,282			7,314
Sale of European operations reclassified into other income, net	18,124			—			—			18,124
Net gain on pension costs reclassified into other income, net	—			—			(814		)	(814		)
Net loss on cash flow hedges reclassified into interest expense, net	—			5,499			—			5,499
Other	60			—			(134		)	(74		)
Other comprehensive income	4,304			23,411			2,334			30,049
Balance as of December 31, 2018	$	(47,299	)	$	(893	)	$	(6,686	)	$	(54,878	)

Preferred Limited Partner [Member]

Distributions Made to Limited Partners and General Partner [Line Items]

Distributions Made to Limited Partner, by Distribution [Table Text Block]

The following table summarizes information about cash distributions declared for our Series A, B and C Preferred Units:



	Cash Distributions Per Unit
Period	Series A		Series B		Series C
December 15, 2018 - March 14, 2019	$	0.53125	$	0.47657	$	0.56250
September 15, 2018 - December 14, 2018	$	0.53125	$	0.47657	$	0.56250
June 15, 2018 - September 14, 2018	$	0.53125	$	0.47657	$	0.56250
March 15, 2018 - June 14, 2018	$	0.53125	$	0.47657	$	0.56250
December 15, 2017 - March 14, 2018	$	0.53125	$	0.47657	N/A
November 30, 2017 - March 14, 2018	N/A		N/A		$	0.65625

NET (LOSS) INCOME PER UNIT (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Schedule of Net (Loss) Income Per Unit [Text Block]

The following table details the calculation of net (loss) income per common unit:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars, Except Unit and Per Unit Data)
Net income	$	205,794		$	147,964		$	150,003
Distributions to preferred limited partners	(92,540		)	(40,448		)	(1,925		)
Distributions to general partner (including incentive distribution rights)	(1,141		)	(54,921		)	(51,284		)
Distributions to common limited partners	(248,705		)	(407,681		)	(342,598		)
Distribution equivalent rights to restricted units	(2,045		)	(2,965		)	(2,697		)
Distributions in excess of earnings	$	(138,637	)	$	(358,051	)	$	(248,501	)

Distributions to common limited partners	$	248,705		$	407,681		$	342,598
Allocation of distributions in excess of earnings	(138,659		)	(350,890		)	(243,530		)
Series D Preferred Unit accretion (refer to Note 19)	(8,195		)	—			—
Loss to common unitholders attributable to the Merger (refer to Note 4)	(377,079		)	—			—
Net (loss) income attributable to common units:	$	(275,228	)	$	56,791		$	99,068

Basic weighted-average common units outstanding	99,490,495			88,825,964			78,080,484

Diluted common units outstanding:
Basic weighted-average common units outstanding	99,490,495			88,825,964			78,080,484
Effect of dilutive potential common units	40,677			—			32,518
Diluted weighted-average common units outstanding	99,531,172			88,825,964			78,113,002

Basic and diluted net (loss) income per common unit	$	(2.77	)	$	0.64		$	1.27

STATEMENTS OF CASH FLOWS (Tables)

12 Months Ended

Dec. 31, 2018

Statement of Cash Flows [Abstract]

Schedule of Changes in Current Assets and Liabilities [Text Block]

Changes in current assets and current liabilities were as follows:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Decrease (increase) in current assets:
Accounts receivable	$	22,482		$	(865	)	$	(23,234	)
Receivable from related parties	160			112			(317		)
Inventories	3,819			11,936			940
Prepaid and other current assets	3,694			3,393			8,128
Increase (decrease) in current liabilities:
Accounts payable	8,003			(30,409		)	14,071
Payable to related party	—			—			894
Accrued interest payable	(4,279		)	6,489			(256		)
Accrued liabilities	39,577			(11,157		)	161
Taxes other than income tax	4,521			(3,529		)	2,690
Income tax payable	285			(2,463		)	639
Changes in current assets and current liabilities	$	78,262		$	(26,493	)	$	3,716

Schedule of Supplemental Cash Flow Information [Text Block]

Cash flows related to interest and income taxes were as follows:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars)
Cash paid for interest, net of amount capitalized	$	183,078	$	158,089	$	142,663
Cash paid for income taxes, net of tax refunds received	$	8,535	$	11,338	$	11,847

EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

Disclosures for our Pension Plans and other postretirement benefit plans



	Pension Plans						Other Postretirement Benefit Plans
	2018			2017			2018			2017
	(Thousands of Dollars)
Change in benefit obligation:
Benefit obligation, January 1	$	149,817		$	127,402		$	12,410		$	11,061
Service cost	9,621			8,955			504			456
Interest cost	4,824			4,507			429			430
Benefits paid	(7,929		)	(5,941		)	(255		)	(342		)
Participant contributions	—			—			87			215
Actuarial (gain) loss	(14,500		)	14,894			(2,267		)	590
Benefit obligation, December 31	$	141,833		$	149,817		$	10,908		$	12,410
Change in plan assets:
Plan assets at fair value, January 1	$	129,878		$	107,644		$	—		$	—
Actual return on plan assets	(6,034		)	17,070			—			—
Employer contributions	11,034			11,105			168			127
Benefits paid	(7,929		)	(5,941		)	(255		)	(342		)
Participant contributions	—			—			87			215
Plan assets at fair value, December 31	$	126,949		$	129,878		$	—		$	—
Reconciliation of funded status:
Fair value of plan assets at December 31	$	126,949		$	129,878		$	—		$	—
Less: Benefit obligation at December 31	141,833			149,817			10,908			12,410
Funded status at December 31	$	(14,884	)	$	(19,939	)	$	(10,908	)	$	(12,410	)
Amounts recognized in the consolidated balance sheets (a):
Accrued liabilities	$	(267	)	$	(210	)	$	(362	)	$	(376	)
Other long-term liabilities	(14,617		)	(19,729		)	(10,546		)	(12,034		)
Net pension liability	$	(14,884	)	$	(19,939	)	$	(10,908	)	$	(12,410	)


(a)	For the Pension Plan, since assets exceed the present value of expected benefit payments for the next 12 months, all of the liability is noncurrent. For the Excess Pension Plan and the other postretirement benefit plans, since there are no assets, the current liability is the present value of expected benefit payments for the next 12 months; the remainder is noncurrent.

The components of net periodic benefit cost (income)

The components of net periodic benefit cost (income) related to our Pension Plans and other postretirement benefit plans were as follows:



	Pension Plans									Other Postretirement Benefit Plans
	Year Ended December 31,									Year Ended December 31,
	2018			2017			2016			2018			2017			2016
	(Thousands of Dollars)
Service cost	$	9,621		$	8,955		$	7,703		$	504		$	456		$	419
Interest cost	4,824			4,507			4,023			429			430			401
Expected return on plan assets	(7,417		)	(6,411		)	(5,407		)	—			—			—
Amortization of prior service credit	(2,057		)	(2,059		)	(2,063		)	(1,145		)	(1,145		)	(1,145		)
Amortization of net actuarial loss	2,174			1,484			1,091			214			191			181
Net periodic benefit cost (income)	$	7,145		$	6,476		$	5,347		$	2		$	(68	)	$	(144	)

Adjustments recognized in other comprehensive (loss) income

Adjustments to other comprehensive income (loss) related to our Pension Plans and other postretirement benefit plans were as follows:



	Pension Plans									Other Postretirement Benefit Plans
	Year Ended December 31,									Year Ended December 31,
	2018			2017			2016			2018			2017			2016
	(Thousands of Dollars)
Net unrecognized gain (loss) arising during the year:
Net actuarial gain (loss)	$	1,049		$	(4,235	)	$	(7,544	)	$	2,267		$	(590	)	$	(368	)
Net (gain) loss reclassified into income:
Amortization of prior service credit	(2,057		)	(2,059		)	(2,063		)	(1,145		)	(1,145		)	(1,145		)
Amortization of net actuarial loss	2,174			1,484			1,091			214			191			181
Net loss (gain) reclassified into income	117			(575		)	(972		)	(931		)	(954		)	(964		)

Reclassification of stranded tax effects	(74		)	—			—			—			—			—
Income tax (expense) benefit	(69		)	162			57			(25		)	22			3
Total changes to other comprehensive income (loss)	$	1,023		$	(4,648	)	$	(8,459	)	$	1,311		$	(1,522	)	$	(1,329	)

The amounts recorded as a component of accumulated other comprehensive (loss) income



	Pension Plans						Other Postretirement Benefit Plans
	December 31,						December 31,
	2018			2017			2018			2017
	(Thousands of Dollars)
Unrecognized actuarial loss	$	(27,955	)	$	(31,178	)	$	(1,673	)	$	(4,154	)
Prior service credit	14,547			16,604			8,319			9,464
Deferred tax asset	76			219			—			25
Accumulated other comprehensive (loss) income, net of tax	$	(13,332	)	$	(14,355	)	$	6,646		$	5,335

Schedule of pre-tax amounts in accumulated other comprehensive loss to be recognized over next fiscal year

The following pre-tax amounts in accumulated other comprehensive loss as of December 31, 2018 are expected to be recognized as components of net periodic benefit cost (income) in 2019:



	Pension Plans			Other Postretirement Benefit Plans
	(Thousands of Dollars)
Actuarial loss	$	846		$	42
Prior service credit	$	(2,057	)	$	(1,145	)

Schedule of fair value of plan assets

The major classes of plan assets measured at fair value for the Pension Plan were as follows:



	December 31, 2018
	Level 1		Level 2		Level 3		Total
	(Thousands of Dollars)
Cash equivalent securities	$	608	$	—	$	—	$	608
Equity securities:
U.S. large cap equity fund (a)	—		70,525		—		70,525
International stock index fund (b)	13,391		—		—		13,391
Fixed income securities:
Bond market index fund (c)	42,425		—		—		42,425
Total	$	56,424	$	70,525	$	—	$	126,949



	December 31, 2017
	Level 1		Level 2		Level 3		Total
	(Thousands of Dollars)
Cash equivalent securities	$	381	$	—	$	—	$	381
Equity securities:
U.S. large cap equity fund (a)	—		75,353		—		75,353
International stock index fund (b)	14,480		—		—		14,480
Fixed income securities:
Bond market index fund (c)	39,664		—		—		39,664
Total	$	54,525	$	75,353	$	—	$	129,878


(a)	This fund is a low-cost equity index fund not actively managed that tracks the S&P 500. Fair values were estimated using pricing models, quoted prices of securities with similar characteristics or discounted cash flows.


(b)	This fund tracks the performance of the Total International Composite Index.


(c)	This fund tracks the performance of the Barclays Capital U.S. Aggregate Bond Index.

Schedule of expected benefit payments

The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid for the years ending December 31:



	Pension Plans		Other Postretirement Benefit Plans
	(Thousands of Dollars)
2019	$	9,454	$	362
2020	$	10,309	$	390
2021	$	11,072	$	423
2022	$	11,593	$	475
2023	$	12,274	$	503
Years 2024-2028	$	68,198	$	3,200

Assumptions used to determine the benefit obligations

The weighted-average assumptions used to determine the benefit obligations were as follows:



	Pension Plans				Other Postretirement Benefit Plans
	December 31,				December 31,
	2018		2017		2018		2017
Discount rate	4.40	%	3.72	%	4.53	%	3.82	%
Rate of compensation increase	3.51	%	3.51	%	n/a		n/a

Assumptions used to determine the net periodic benefit cost (income)

The weighted-average assumptions used to determine the net periodic benefit cost (income) were as follows:



	Pension Plans						Other Postretirement Benefit Plans
	Year Ended December 31,						Year Ended December 31,
	2018		2017		2016		2018		2017		2016
Discount rate	3.72	%	4.33	%	4.61	%	3.82	%	4.49	%	4.75	%
Expected long-term rate of return on plan assets	6.50	%	6.00	%	6.25	%	n/a		n/a		n/a
Rate of compensation increase	3.51	%	3.51	%	3.51	%	n/a		n/a		n/a

Schedule of assumed health care cost trend rates

The assumed health care cost trend rates were as follows:



	December 31,
	2018		2017
Health care cost trend rate assumed for next year	6.84	%	6.84	%
Rate to which the cost trend rate was assumed to decrease (the ultimate trend rate)	5.00	%	5.00	%
Year that the rate reaches the ultimate trend rate	2028		2028

UNIT-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2018

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of long-term incentive plan compensation expense

The following table summarizes information pertaining to both long-term incentive plans:



	Units Outstanding December 31,			Compensation Expense Year Ended December 31,
	2018	2017	2016	2018		2017		2016
				(Thousands of Dollars)
Restricted Units:
Domestic employees	1,028,484	736,746	647,340	$	8,233	$	7,881	$	5,980
Non-employee directors (NEDs)	59,752	27,097	18,134	524		251		388
International employees	30,918	58,107	50,609	1,158		595		715
Performance Units	158,326	80,961	77,014	1,889		—		1,211
Unit Awards	—	—	—	1,358		—		—
Total	1,277,480	902,911	793,097	$	13,162	$	8,727	$	8,294

Restricted unit award activity

A summary of our restricted unit activity is as follows:



	Domestic Employees
	Number of Restricted Units		Weighted- Average Grant-Date Fair Value Per Unit		Number of Restricted Units to NEDs		Number of Restricted Units to International Employees
Nonvested units as of January 1, 2016	—		$	—	—		—
Transferred on March 1, 2016	586,524		35.03		17,629		49,121
Granted	246,070		47.70		8,730		20,107
Vested	(180,724	)	35.50		(8,225	)	(14,812	)
Forfeited	(4,530	)	35.03		—		(3,807	)
Nonvested units as of December 31, 2016	647,340		39.72		18,134		50,609
Granted	307,009		29.56		17,110		24,533
Vested	(201,466	)	38.74		(8,147	)	(16,440	)
Forfeited	(16,137	)	40.00		—		(595	)
Nonvested units as of December 31, 2017	736,746		35.95		27,097		58,107
Converted on July 20, 2018	53,447		24.99		18,915		—
Granted	518,282		24.07		34,303		16,197
Vested	(235,746	)	35.12		(20,563	)	(41,406	)
Forfeited	(44,245	)	36.05		—		(1,980	)
Nonvested units as of December 31, 2018	1,028,484		$	29.47	59,752		30,918

Performance Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of long-term incentive plan compensation expense

A summary of our performance units is shown below:



			Granted for Accounting Purposes
	Total Performance Units Awarded		Performance Units		Weighted-Average Grant Date Fair Value per Unit
Outstanding as of January 1, 2017	77,014		35,373		$	31.75
Granted	39,320		38,865		50.04
Additional grant upon conversion (related to 2016 performance)	17,690		17,690		31.75
Vested (related to 2016 performance)	(53,063	)	(53,063	)	31.75
Outstanding as of December 31, 2017	80,961		38,865		$	50.04
Granted	116,230		80,690		$	23.43
Vested	—		—		—
Forfeitures	(38,865	)	(38,865	)	$	50.04
Outstanding as of December 31, 2018	158,326		80,690		23.43

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Components of income tax expense related to certain of our continuing operations conducted through separate taxable wholly owned corporate subsidiaries were as follows:



	Year Ended December 31,
	2018		2017			2016
	(Thousands of Dollars)
Current:
U.S.	$	4,515	$	3,117		$	2,280
Foreign	4,658		6,335			6,329
Foreign withholding tax	192		479			3,833
Total current	9,365		9,931			12,442

Deferred:
U.S.	1,403		1,468			2,680
Foreign	394		(1,065		)	(1,122		)
Foreign withholding tax	246		(397		)	(2,027		)
Total deferred	2,043		6			(469		)

Total income tax expense	$	11,408	$	9,937		$	11,973

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

The tax effects of significant temporary differences representing deferred income tax assets and liabilities were as follows:



	December 31,
	2018			2017
	(Thousands of Dollars)
Deferred income tax assets:
Net operating losses	$	21,009		$	20,688
Employee benefits	362			483
Environmental and legal reserves	239			185
Allowance for bad debt	1,970			1,982
Other	1,796			2,050
Total deferred income tax assets	25,376			25,388
Less: Valuation allowance	(12,442		)	(11,251		)
Net deferred income tax assets	12,934			14,137

Deferred income tax liabilities:
Property, plant and equipment	(25,128		)	(36,176		)
Foreign withholding tax	(234		)	—
Total deferred income tax liabilities	(25,362		)	(36,176		)

Net deferred income tax liability	$	(12,428	)	$	(22,039	)

Reported on the consolidated balance sheets as:
Deferred income tax asset	$	—		$	233
Deferred income tax liability	(12,428		)	(22,272		)
Net deferred income tax liability	$	(12,428	)	$	(22,039	)

SEGMENT INFORMATION (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Text Block]

Results of operations for the reportable segments were as follows:



	Year Ended December 31,
	2018			2017			2016
	(Thousands of Dollars)
Revenues:
Pipeline	$	611,065		$	516,288		$	485,650
Storage:
Third parties	598,380			604,847			589,098
Intersegment	7,570			12,106			20,944
Total storage	605,950			616,953			610,042
Fuels marketing	752,312			692,884			681,934
Consolidation and intersegment eliminations	(7,570		)	(12,106		)	(20,944		)
Total revenues	$	1,961,757		$	1,814,019		$	1,756,682

Depreciation and amortization expense:
Pipeline	$	153,943		$	128,061		$	89,554
Storage	135,056			127,473			118,663
Total segment depreciation and amortization expense	288,999			255,534			208,217
Other depreciation and amortization expense	8,875			8,698			8,519
Total depreciation and amortization expense	$	297,874		$	264,232		$	216,736

Operating income:
Pipeline	$	272,695		$	231,795		$	248,238
Storage	181,471			219,439			214,801
Fuels marketing	24,440			5,983			3,406
Consolidation and intersegment eliminations	32			(1		)	—
Total segment operating income	478,638			457,216			466,445
General and administrative expenses	106,200			112,240			98,817
Other depreciation and amortization expense	8,875			8,698			8,519
Total operating income	$	363,563		$	336,278		$	359,109

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

Revenues by geographic area are shown in the table below:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars)
United States	$	1,481,863	$	1,406,626	$	1,352,936
Netherlands	398,382		322,251		313,395
Other	81,512		85,142		90,351
Consolidated revenues	$	1,961,757	$	1,814,019	$	1,756,682

Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]

Total amounts of property, plant and equipment, net by geographic area were as follows:



	December 31,
	2018		2017
	(Thousands of Dollars)
United States	$	3,687,910	$	3,519,965
Netherlands	514,541		572,817
Other	86,171		208,151
Consolidated long-lived assets	$	4,288,622	$	4,300,933

Schedule of Segment Reporting Information Assets By Segment [Text Block]

Total assets by reportable segment were as follows:



	December 31,
	2018		2017
	(Thousands of Dollars)
Pipeline	$	3,637,226	$	3,492,417
Storage	2,424,342		2,735,563
Fuels marketing	112,906		118,746
Total segment assets	6,174,474		6,346,726
Other partnership assets	174,666		188,507
Total consolidated assets	$	6,349,140	$	6,535,233

Schedule of Capital Expenditures, by Segment [Table Text Block]

Capital expenditures, including acquisitions, by reportable segment were as follows:



	Year Ended December 31,
	2018		2017		2016
	(Thousands of Dollars)
Pipeline	$	288,035	$	1,596,311	$	88,373
Storage	202,782		244,398		206,641
Other partnership assets	4,137		5,648		5,001
Total capital expenditures	$	494,954	$	1,846,357	$	300,015

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS (Tables)

12 Months Ended

Dec. 31, 2018

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS [Abstract]

Condensed Consolidating Balance Sheets [Table Text Block]

Condensed Consolidating Balance Sheets

December 31, 2018

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics		NuPOP		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets
Cash and cash equivalents	$	1,255	$	51	$	—	$	12,338	$	—		$	13,644
Receivables, net	—		2,212		—		146,096		—			148,308
Inventories	—		1,741		5,237		15,735		—			22,713
Prepaid and other current assets	61		14,422		908		2,102		—			17,493
Intercompany receivable	—		1,327,833		—		500,583		(1,828,416		)	—
Total current assets	1,316		1,346,259		6,145		676,854		(1,828,416		)	202,158
Property, plant and equipment, net	—		1,858,264		615,549		1,814,809		—			4,288,622
Intangible assets, net	—		49,107		—		683,949		—			733,056
Goodwill	—		149,453		170,652		716,871		—			1,036,976
Investment in wholly owned subsidiaries	3,355,636		1,750,256		1,425,283		857,485		(7,388,660		)	—
Other long-term assets, net	304		54,429		26,716		6,879		—			88,328
Total assets	$	3,357,256	$	5,207,768	$	2,244,345	$	4,756,847	$	(9,217,076	)	$	6,349,140
Liabilities, Mezzanine Equity and Partners’ Equity
Accounts payable	$	6,460	$	39,680	$	6,331	$	90,650	$	—		$	143,121
Short-term debt	—		18,500		—		—		—			18,500
Accrued interest payable	—		36,253		—		40		—			36,293
Accrued liabilities	1,280		24,858		8,082		67,773		—			101,993
Taxes other than income tax	125		7,285		4,718		6,955		—			19,083
Income tax payable	—		457		2		3,986		—			4,445
Intercompany payable	472,790		—		1,355,626		—		(1,828,416		)	—
Total current liabilities	480,655		127,033		1,374,759		169,404		(1,828,416		)	323,435
Long-term debt	—		3,050,531		—		61,465		—			3,111,996
Deferred income tax liability	—		1,675		9		10,744		—			12,428
Other long-term liabilities	—		28,392		12,348		38,818		—			79,558
Series D preferred units	563,992		—		—		—		—			563,992
Total partners’ equity	2,312,609		2,000,137		857,229		4,476,416		(7,388,660		)	2,257,731
Total liabilities, mezzanine equity and partners’ equity	$	3,357,256	$	5,207,768	$	2,244,345	$	4,756,847	$	(9,217,076	)	$	6,349,140

Condensed Consolidating Balance Sheets

December 31, 2017

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics		NuPOP		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Assets
Cash and cash equivalents	$	885	$	29	$	—	$	23,378	$	—		$	24,292
Receivables, net	—		280		—		176,495		—			176,775
Inventories	—		1,686		8,611		16,560		—			26,857
Prepaid and other current assets	61		11,412		4,191		6,844		—			22,508
Intercompany receivable	—		3,112,164		—		—		(3,112,164		)	—
Total current assets	946		3,125,571		12,802		223,277		(3,112,164		)	250,432
Property, plant and equipment, net	—		1,893,720		591,070		1,816,143		—			4,300,933
Intangible assets, net	—		58,530		—		725,949		—			784,479
Goodwill	—		149,453		170,652		777,370		—			1,097,475
Investment in wholly owned subsidiaries	2,891,371		24,162		1,301,717		790,882		(5,008,132		)	—
Deferred income tax asset	—		—		—		233		—			233
Other long-term assets, net	303		65,684		27,493		8,201		—			101,681
Total assets	$	2,892,620	$	5,317,120	$	2,103,734	$	4,342,055	$	(8,120,296	)	$	6,535,233
Liabilities and Partners’ Equity
Accounts payable	$	4,078	$	27,642	$	13,160	$	101,052	$	—		$	145,932
Short-term debt	—		35,000		—		—		—			35,000
Current portion of long-term debt	—		349,990		—		—		—			349,990
Accrued interest payable	—		40,402		—		47		—			40,449
Accrued liabilities	1,105		17,628		9,450		33,395		—			61,578
Taxes other than income tax	125		7,110		3,794		3,356		—			14,385
Income tax payable	—		732		4		3,436		—			4,172
Intercompany payable	322,296		—		1,277,691		1,512,177		(3,112,164		)	—
Total current liabilities	327,604		478,504		1,304,099		1,653,463		(3,112,164		)	651,506
Long-term debt, less current portion	—		3,201,220		—		61,849		—			3,263,069
Deferred income tax liability	—		1,262		12		20,998		—			22,272
Other long-term liabilities	—		58,806		8,861		50,630		—			118,297
Total partners’ equity	2,565,016		1,577,328		790,762		2,555,115		(5,008,132		)	2,480,089
Total liabilities and partners’ equity	$	2,892,620	$	5,317,120	$	2,103,734	$	4,342,055	$	(8,120,296	)	$	6,535,233

Condensed Consolidating Statements of Income (Loss) [Table Text Block]

Condensed Consolidating Statements of Income (Loss)

For the Year Ended December 31, 2018

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries		Eliminations			Consolidated
Revenues	$	—		$	485,603		$	260,679		$	1,216,180	$	(705	)	$	1,961,757
Costs and expenses	2,407			317,286			163,667			1,115,539		(705		)	1,598,194
Operating (loss) income	(2,407		)	168,317			97,012			100,641		—			363,563
Equity in earnings of subsidiaries	207,973			17,167			121,913			212,249		(559,302		)	—
Interest income (expense), net	228			(191,835		)	(7,127		)	12,497		—			(186,237		)
Other income, net	—			3,876			446			35,554		—			39,876
Income (loss) before income tax expense (benefit)	205,794			(2,475		)	212,244			360,941		(559,302		)	217,202
Income tax expense (benefit)	—			588			(3		)	10,823		—			11,408
Net income (loss)	$	205,794		$	(3,063	)	$	212,247		$	350,118	$	(559,302	)	$	205,794

Condensed Consolidating Statements of Income (Loss)

For the Year Ended December 31, 2017

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues	$	—		$	496,454		$	221,125		$	1,097,458		$	(1,018	)	$	1,814,019
Costs and expenses	1,868			317,871			146,243			1,012,777			(1,018		)	1,477,741
Operating (loss) income	(1,868		)	178,583			74,882			84,681			—			336,278
Equity in earnings (loss) of subsidiaries	149,775			(10,616		)	89,405			158,700			(387,264		)	—
Interest income (expense), net	57			(176,897		)	(5,587		)	9,344			—			(173,083		)
Other income (expense), net	—			145			3			(5,442		)	—			(5,294		)
Income (loss) before income tax (benefit) expense	147,964			(8,785		)	158,703			247,283			(387,264		)	157,901
Income tax (benefit) expense	—			(820		)	2			10,755			—			9,937
Net income (loss)	$	147,964		$	(7,965	)	$	158,701		$	236,528		$	(387,264	)	$	147,964

Condensed Consolidating Statements of Income (Loss)

For the Year Ended December 31, 2016

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Revenues	$	—		$	511,650		$	224,966		$	1,021,804		$	(1,738	)	$	1,756,682
Costs and expenses	1,806			302,099			150,384			945,022			(1,738		)	1,397,573
Operating (loss) income	(1,806		)	209,551			74,582			76,782			—			359,109
Equity in earnings (loss) of subsidiaries	151,794			(13,769		)	82,202			156,036			(376,263		)	—
Interest (expense) income, net	—			(139,827		)	(744		)	2,221			—			(138,350		)
Other income (expense), net	18			(58,264		)	(26		)	(511		)	—			(58,783		)
Income (loss) before income tax expense (benefit)	150,006			(2,309		)	156,014			234,528			(376,263		)	161,976
Income tax expense (benefit)	3			1,607			(23		)	10,386			—			11,973
Net income (loss)	$	150,003		$	(3,916	)	$	156,037		$	224,142		$	(376,263	)	$	150,003

Condensed Consolidating Statements of Comprehensive Income (Loss) [Table Text Block]

Condensed Consolidating Statements of Comprehensive Income

For the Year Ended December 31, 2018

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics			NuPOP		Non-Guarantor Subsidiaries		Eliminations			Consolidated
Net income (loss)	$	205,794	$	(3,063	)	$	212,247	$	350,118	$	(559,302	)	$	205,794

Other comprehensive income:
Foreign currency translation adjustment	—		—			—		4,304		—			4,304
Net gain on pension and other postretirement benefit adjustments, net of tax expense	—		—			—		2,334		—			2,334
Net gain on cash flow hedges	—		23,411			—		—		—			23,411
Total other comprehensive income	—		23,411			—		6,638		—			30,049
Comprehensive income	$	205,794	$	20,348		$	212,247	$	356,756	$	(559,302	)	$	235,843

Condensed Consolidating Statements of Comprehensive Income (Loss)

For the Year Ended December 31, 2017

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics			NuPOP		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	147,964	$	(7,965	)	$	158,701	$	236,528		$	(387,264	)	$	147,964

Other comprehensive income (loss):
Foreign currency translation adjustment	—		—			—		17,466			—			17,466
Net loss on pension and other postretirement benefit adjustments, net of tax benefit	—		—			—		(6,170		)	—			(6,170		)
Net loss on cash flow hedges	—		(2,046		)	—		—			—			(2,046		)
Total other comprehensive (loss) income	—		(2,046		)	—		11,296			—			9,250
Comprehensive income (loss)	$	147,964	$	(10,011	)	$	158,701	$	247,824		$	(387,264	)	$	157,214

Condensed Consolidating Statements of Comprehensive Income

For the Year Ended December 31, 2016

(Thousands of Dollars)



	NuStar Energy		NuStar Logistics			NuPOP		Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net income (loss)	$	150,003	$	(3,916	)	$	156,037	$	224,142		$	(376,263	)	$	150,003

Other comprehensive income (loss):
Foreign currency translation adjustment	—		—			—		(8,243		)	—			(8,243		)
Net loss on pension and other postretirement benefit adjustments, net of tax benefit	—		—			—		(2,850		)	—			(2,850		)
Net gain on cash flow hedges	—		5,710			—		—			—			5,710
Total other comprehensive income (loss)	—		5,710			—		(11,093		)	—			(5,383		)
Comprehensive income	$	150,003	$	1,794		$	156,037	$	213,049		$	(376,263	)	$	144,620

Condensed Consolidating Statements of Cash Flows [Table Text Block]

Condensed Consolidating Statements of Cash Flows

For the Year Ended December 31, 2018

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided by operating activities	$	444,233		$	100,385		$	179,512		$	514,936		$	(694,859	)	$	544,207
Cash flows from investing activities:
Capital expenditures	—			(71,044		)	(19,152		)	(367,256		)	—			(457,452		)
Change in accounts payable related to capital expenditures	—			11,101			(5,161		)	(13,623		)	—			(7,683		)
Acquisitions	—			—			(37,502		)	—			—			(37,502		)
Proceeds from insurance recoveries	—			—			—			78,419			—			78,419
Proceeds from sale of European operations	—			—			—			266,740			—			266,740
Proceeds from sale or disposition of assets	—			2,674			31			995			—			3,700
Investment in subsidiaries	(708,600		)	(1,711,975		)	(54,600		)	(54,665		)	2,529,840			—
Net cash used in investing activities	(708,600		)	(1,769,244		)	(116,384		)	(89,390		)	2,529,840			(153,778		)
Cash flows from financing activities:
Debt borrowings	—			1,840,853			—			31,800			—			1,872,653
Debt repayments	—			(2,349,476		)	—			(32,300		)	—			(2,381,776		)
Issuance of Series D preferred units	590,000			—			—			—			—			590,000
Payment of issuance costs for Series D preferred units	(34,203		)	—			—			—			—			(34,203		)
Issuance of common units, net of issuance costs	10,000			—			—			—			—			10,000
General partner contribution	204			—			—			—			—			204
Distributions to preferred unitholders	(90,670		)	(45,336		)	(45,336		)	(45,335		)	136,007			(90,670		)
Distributions to common unitholders and general partner	(300,777		)	(150,388		)	(150,388		)	(150,408		)	451,184			(300,777		)
Cash consideration for Merger (Note 4)	(67,936		)	—			—			141			—			(67,795		)
Proceeds from termination of interest rate swaps	—			8,048			—			—			—			8,048
Contributions from affiliates	—			599,400			54,600			1,768,172			(2,422,172		)	—
Net intercompany activity	162,498			1,766,881			77,996			(2,007,375		)	—			—
Other, net	(4,379		)	(1,101		)	—			(71		)	—			(5,551		)
Net cash provided by (used in) financing activities	264,737			1,668,881			(63,128		)	(435,376		)	(1,834,981		)	(399,867		)
Effect of foreign exchange rate changes on cash	—			—			—			(1,210		)	—			(1,210		)
Net increase (decrease) in cash and cash equivalents	370			22			—			(11,040		)	—			(10,648		)
Cash and cash equivalents as of the beginning of the period	885			29			—			23,378			—			24,292
Cash and cash equivalents as of the end of the period	$	1,255		$	51		$	—		$	12,338		$	—		$	13,644

Condensed Consolidating Statements of Cash Flows

For the Year Ended December 31, 2017

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided by operating activities	$	483,481		$	152,101		$	102,405		$	405,950		$	(737,138	)	$	406,799
Cash flows from investing activities:
Capital expenditures	—			(47,600		)	(35,041		)	(301,997		)	—			(384,638		)
Change in accounts payable related to capital expenditures	—			(1,988		)	5,964			32,927			—			36,903
Acquisitions	—			—			—			(1,461,719		)	—			(1,461,719		)
Proceeds from Axeon term loan	—			110,000			—			—			—			110,000
Proceeds from insurance recoveries	—			—			—			977			—			977
Proceeds from sale or disposition of assets	—			1,955			18			63			—			2,036
Investment in subsidiaries	(1,262,000		)	—			—			(126		)	1,262,126			—
Net cash (used in) provided by investing activities	(1,262,000		)	62,367			(29,059		)	(1,729,875		)	1,262,126			(1,696,441		)
Cash flows from financing activities:
Debt borrowings	—			2,969,400			—			90,700			—			3,060,100
Debt repayments	—			(2,400,739		)	—			(86,800		)	—			(2,487,539		)
Issuance of preferred units, net of issuance costs	538,560			—			—			—			—			538,560
Issuance of common units, net of issuance costs	643,878			—			—			—			—			643,878
General partner contribution	13,737			—			—			—			—			13,737
Distributions to preferred unitholders	(38,833		)	(19,417		)	(19,416		)	(19,418		)	58,251			(38,833		)
Distributions to common unitholders and general partner	(446,306		)	(223,153		)	(223,153		)	(223,176		)	669,482			(446,306		)
Contributions from (distributions to) affiliates	—			1,262,000			—			(9,279		)	(1,252,721		)	—
Net intercompany activity	73,206			(1,801,218		)	169,223			1,558,789			—			—
Other, net	(5,708		)	(1,317		)	—			(300		)	—			(7,325		)
Net cash provided by (used in) financing activities	778,534			(214,444		)	(73,346		)	1,310,516			(524,988		)	1,276,272
Effect of foreign exchange rate changes on cash	—			—			—			1,720			—			1,720
Net increase (decrease) in cash and cash equivalents	15			24			—			(11,689		)	—			(11,650		)
Cash and cash equivalents as of the beginning of the period	870			5			—			35,067			—			35,942
Cash and cash equivalents as of the end of the period	$	885		$	29		$	—		$	23,378		$	—		$	24,292

Condensed Consolidating Statements of Cash Flows

For the Year Ended December 31, 2016

(Thousands of Dollars)



	NuStar Energy			NuStar Logistics			NuPOP			Non-Guarantor Subsidiaries			Eliminations			Consolidated
Net cash provided by operating activities	$	391,773		$	167,900		$	211,816		$	359,283		$	(694,011	)	$	436,761
Cash flows from investing activities:
Capital expenditures	—			(64,334		)	(52,637		)	(87,387		)	—			(204,358		)
Change in accounts payable related to capital expenditures	—			(10,076		)	(285		)	(702		)	—			(11,063		)
Acquisitions	—			(95,657		)	—			—			—			(95,657		)
Investment in subsidiaries	—			—			(212,900		)	—			212,900			—
Net cash used in investing activities	—			(170,067		)	(265,822		)	(88,089		)	212,900			(311,078		)
Cash flows from financing activities:
Debt borrowings	—			1,365,529			—			41,200			—			1,406,729
Debt repayments	—			(1,419,852		)	—			(36,300		)	—			(1,456,152		)
Issuance of preferred units, net of issuance costs	218,400			—			—			—			—			218,400
Issuance of common units, net of issuance costs	27,710			—			—			—			—			27,710
General partner contribution	680			—			—			—			—			680
Distributions to common unitholders and general partner	(392,962		)	(196,481		)	(196,481		)	(196,501		)	589,463			(392,962		)
Contributions from affiliates	—			—			—			108,352			(108,352		)	—
Net intercompany activity	(241,131		)	255,326			250,487			(264,682		)	—			—
Other, net	(4,485		)	(2,354		)	—			(8,890		)	—			(15,729		)
Net cash (used in) provided by financing activities	(391,788		)	2,168			54,006			(356,821		)	481,111			(211,324		)
Effect of foreign exchange rate changes on cash	—			—			—			2,721			—			2,721
Net (decrease) increase in cash and cash equivalents	(15		)	1			—			(82,906		)	—			(82,920		)
Cash and cash equivalents as of the beginning of the period	885			4			—			117,973			—			118,862
Cash and cash equivalents as of the end of the period	$	870		$	5		$	—		$	35,067		$	—		$	35,942

QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2018

Selected Quarterly Financial Information [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

The following table summarizes quarterly financial data for the years ended December 31, 2018 and 2017:



	First Quarter		Second Quarter		Third Quarter			Fourth Quarter			Total
	(Thousands of Dollars, Except Per Unit Data)
2018:
Revenues	$	475,881	$	486,204	$	490,363		$	509,309		$	1,961,757
Operating income	$	98,480	$	79,838	$	95,277		$	89,968		$	363,563
Net income	$	126,133	$	29,399	$	48,136		$	2,126		$	205,794
Basic and diluted net income (loss) per common unit	$	1.15	$	0.15	$	(3.49	)	$	(0.31	)	$	(2.77	)
Cash distributions per unit applicable to common limited partners	$	0.60	$	0.60	$	0.60		$	0.60		$	2.40

2017:
Revenues	$	487,430	$	435,488	$	440,566		$	450,535		$	1,814,019
Operating income	$	97,139	$	73,404	$	91,717		$	74,018		$	336,278
Net income	$	57,940	$	26,250	$	38,592		$	25,182		$	147,964
Basic and diluted net income per common unit	$	0.49	$	0.05	$	0.15		$	0.00		$	0.64
Cash distributions per unit applicable to common limited partners	$	1.095	$	1.095	$	1.095		$	1.095		$	4.380

Basic and diluted net income (loss) per common unit also includes the impact of the $377.1 million loss as a result of the Merger. Please refer to Notes 4 and 21 for further discussion.

ORGANIZATION AND OPERATIONS Narrative 1 (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of European operations		$ 266,740	$ 0	$ 0
Non-cash loss on sale of assets		(43,366)	$ 0	$ 0
Sale of U.K. and Amsterdam Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of European operations	$ 270,000
Description of assets sold	six liquids storage terminals in the United Kingdom and one facility in Amsterdam
Sale of U.K. and Amsterdam Operations [Member] \| Other Nonoperating Income (Expense) [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-cash loss on sale of assets		$ (43,400)

ORGANIZATION AND OPERATIONS Narrative 2 (Details) - USD ($) $ / shares in Units, $ in Thousands			9 Months Ended	12 Months Ended
	Jun. 29, 2018	Apr. 18, 2017	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2016	Jul. 20, 2018	Jul. 13, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Net proceeds from issuance of Series D preferred units				$ 555,797
Common unit conversion rate						55.00%
Series D preferred units outstanding				23,246,650				0
Series D Preferred Limited Partner [Member]
Class of Stock [Line Items]
Issuance of preferred units (temporary equity) (in units)	15,760,441						7,486,209
Units issued, price per unit	$ 25.38						$ 25.38
Net proceeds from issuance of Series D preferred units	$ 370,700		$ 555,800	$ 555,797
Series D preferred units outstanding			23,246,650
Common Limited Partner [Member]
Class of Stock [Line Items]
Units issued, price per unit	$ 24.17	$ 46.35
Issuance of units (permanent equity) (in units)	413,736	14,375,000			595,050

ORGANIZATION AND OPERATIONS Narrative 3 (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unusual or Infrequent Item, or Both [Line Items]
Insurance proceeds	$ 87,500		$ 12,500
Gain (loss) related to hurricane activity		$ 78,756	(5,000)	$ 0
Business Interruption Loss From Hurricane [Member]
Unusual or Infrequent Item, or Both [Line Items]
Insurance proceeds	$ 9,100		3,800
Other Nonoperating Income (Expense) [Member]
Unusual or Infrequent Item, or Both [Line Items]
Gain (loss) related to hurricane activity		$ 78,800	$ (5,000)

ORGANIZATION AND OPERATIONS Narrative 4 (Details) - USD ($) $ in Thousands						12 Months Ended
	Jun. 29, 2018	May 04, 2017	Apr. 28, 2017	Apr. 18, 2017	Feb. 22, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 26, 2014
Class of Stock [Line Items]
Net proceeds from issuance of units						$ 10,204	$ 657,475	$ 28,285
Debt Instrument [Line Items]
Proceeds from note offering, net of issuance costs						0	543,333	0
Financing Receivable, Impaired [Line Items]
Proceeds from Axeon term loan						0	110,000	$ 0
Common Limited Partner [Member]
Class of Stock [Line Items]
Issuance of units (units)	413,736			14,375,000				595,050
Proceeds from common unit issuance including general partner contribution	$ 10,200			$ 657,500				$ 28,300
Net proceeds from issuance of units						$ 10,000	$ 643,878	27,710
Series B Preferred Limited Partner [Member]
Class of Stock [Line Items]
Issuance of units (units)			15,400,000
Preferred units distribution percentage			7.625%
Net proceeds from issuance of units			$ 371,800
5.625% senior notes
Debt Instrument [Line Items]
Senior notes issued			$ 550,000
Stated interest rate			5.625%			5.625%
Proceeds from note offering, net of issuance costs			$ 543,300
Axeon [Member]
Financing Receivable, Impaired [Line Items]
Axeon Term Loan Receivable									$ 190,000
Maximum Amount Guarantees								$ 125,000
Proceeds from Axeon term loan					$ 110,000
Navigator Acquisition [Member]
Business Acquisition [Line Items]
Purchase price of Navigator Acquisition		$ 1,500,000

ORGANIZATION AND OPERATIONS Narrative 5 (Details) bbl in Millions	12 Months Ended
	Dec. 31, 2018 mi bbl
Segment Information
Number of business segments	3
Pipeline Segment \| Central West Refined Products Pipelines
Segment Information
Pipeline length, in miles	3,130
Pipeline Segment \| Crude Oil Pipelines
Segment Information
Pipeline length, in miles	2,070
Storage capacity, in barrels \| bbl	5.0
Pipeline Segment \| East and North Pipelines
Segment Information
Pipeline length, in miles	2,600
Storage capacity, in barrels \| bbl	7.3
Pipeline Segment \| Ammonia Pipeline
Segment Information
Pipeline length, in miles	2,000
Storage Segment
Segment Information
Storage capacity, in barrels \| bbl	75.8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Narrative (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill impairment loss		$ 0	$ 0
Goodwill		1,036,976,000	1,097,475,000	$ 696,637,000
Unrecognized tax benefits		$ 0	0
Tax years subject to examination		For U.S. federal and state purposes, as well as for our major non-U.S. jurisdictions, tax years subject to examination are 2015 through 2017, according to standard statute of limitations.
Asset retirement obligation		$ 200,000	$ 700,000
Payment terms		Generally, payment terms do not exceed 30 days.
General partner ownership interest	2.00%		2.00%	2.00%
Common Limited Partner [Member]
Common unitholders ownership interest	98.00%
General Partner [Member]
General partner ownership interest	2.00%
St. Eustatius Bunkers [Member]
Reporting unit, percentage of fair value in excess of carrying amount		2.00%
Goodwill		$ 31,100,000

NEW ACCOUNTING PRONOUNCEMENTS Narrative (Details) - Leases [Member] - Subsequent Event [Member]	3 Months Ended
	Mar. 31, 2019
Subsequent Event [Line Items]
Transition adjustment	The transition adjustment related to the adoption was immaterial.
Lease assets, description	Right-of-use assets were less than 5% of total assets as of January 1, 2019, and lease liabilities did not significantly differ from right-of-use assets.

MERGER AND RELATED PARTY AGREEMENTS Narrative 1 (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 20, 2018
Class of Stock [Line Items]
Approximate cash consideration for merger			$ 68,000
Cash consideration for merger			$ 67,795	$ 0	$ 0
General partner ownership interest		2.00%		2.00%	2.00%
Common unit conversion rate						55.00%
Number of common limited partner units owned by general partner		10.2
Common Limited Partner [Member]
Class of Stock [Line Items]
Issuance of NuStar Energy common units as a result of the Merger, units issued	23.6
Issuance of NuStar Energy common units as a result of the Merger, incremental units issued	13.4

MERGER AND RELATED PARTY AGREEMENTS Table - Merger Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jul. 20, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Fair value of incremental NS common units issued	$ 335,106
NSH debt and assumed net current liabilities	52,075
Transaction costs	15,897
Total consideration	403,078
Carrying value of general partner interest	$ 25,999	$ 0	$ 37,826
Loss to common unitholders attributable to the Merger		$ (377,079)	$ 0	$ 0
Basic weighted-average common units outstanding		99,490,495	88,825,964	78,080,484
Loss per common unit attributable to the Merger		$ (3.79)

MERGER AND RELATED PARTY AGREEMENTS Narrative 2 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
General and administrative expenses	$ 0	$ 0	$ 10,493
NuStar GP, LLC [Member]
Related Party Transaction [Line Items]
Administrative fees, description	(the Amended GP Services Agreement), which provided that we furnish administrative services necessary to conduct the business of NuStar GP Holdings, and NuStar GP Holdings compensated us for these services for an annual fee of $1.0 million, subject to adjustment based on the annual merit increase percentage applicable to our employees for the most recently completed fiscal year and for changes in level of service. We terminated the Amended GP Services Agreement in conjunction with the Merger.

DISPOSITION AND ACQUISITIONS Narrative 1 (Details) $ in Thousands, bbl in Millions		12 Months Ended
	Nov. 30, 2018 USD ($) bbl	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of European operations		$ 266,740	$ 0	$ 0
Non-cash loss on sale of assets		(43,366)	$ 0	$ 0
Sale of U.K. and Amsterdam Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of European operations	$ 270,000
Description of assets sold	six liquids storage terminals in the United Kingdom and one facility in Amsterdam
Storage capacity, in barrels \| bbl	9.5
Sale of U.K. and Amsterdam Operations [Member] \| Other Nonoperating Income (Expense) [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-cash loss on sale of assets		$ (43,400)

DISPOSITION AND ACQUISITIONS Narrative 2 (Details) - CHS Acquisition [Member] $ in Millions	Apr. 16, 2018 USD ($)
Business Acquisition [Line Items]
Description of CHS Acquisition	On April 16, 2018, we acquired CHS Inc.’s Council Bluffs pipeline system, comprised of a 227-mile pipeline and 18 storage tanks,
Purchase price of CHS Acquisition	$ 37.5

DISPOSITION AND ACQUISITIONS Narrative 3 (Details) $ in Billions	May 04, 2017 USD ($)
Navigator Acquisition [Member]
Business Acquisition [Line Items]
Purchase price of Navigator Acquisition	$ 1.5

DISPOSITION AND ACQUISITIONS Table 1 - Navigator Acquisition Purchase Price Allocation (Details) - USD ($) $ in Thousands	May 04, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 1,036,976	$ 1,097,475	$ 696,637
Navigator Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable	$ 4,747
Other current assets	2,359
Property, plant and equipment, net	376,690
Intangible assets	700,000
Goodwill	398,024
Other long-term assets, net	2,199
Current liabilities	(22,300)
Purchase price allocation, net of cash acquired	$ 1,461,719
Intangible assets, weighted average useful life (years)	20 years

DISPOSITION AND ACQUISITIONS Narrative 4 (Details) - USD ($) $ in Thousands				6 Months Ended	9 Months Ended	12 Months Ended
	Jun. 29, 2018	Apr. 28, 2017	Apr. 18, 2017	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Contributions from general partner						$ 204	$ 13,737	$ 680
General partner ownership interest				2.00%			2.00%	2.00%
Common Limited Partner [Member]
Business Acquisition [Line Items]
Issuance of units (units)	413,736		14,375,000					595,050
General Partner [Member]
Business Acquisition [Line Items]
Contributions from general partner			$ 13,600		$ 200			$ 600
General partner ownership interest				2.00%
Series B Preferred Limited Partner [Member]
Business Acquisition [Line Items]
Issuance of units (units)		15,400,000
5.625% senior notes
Business Acquisition [Line Items]
Senior notes issued		$ 550,000
Stated interest rate		5.625%				5.625%

DISPOSITION AND ACQUISITIONS Table 2 - Navigator Pro Forma Information (Details) - Navigator Acquisition [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Revenues	$ 1,828,418	$ 1,782,932
Net income	$ 127,433	$ 78,664
Basic net income per common unit	$ 0.31	$ 0.01
Diluted net income per common unit	$ 0.31	$ 0.01
Transaction costs	$ 14,100

DISPOSITION AND ACQUISITIONS Narrative 5 (Details) bbl in Thousands, $ in Thousands		12 Months Ended
	Dec. 21, 2016 USD ($) bbl	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Net purchase price of acquisition		$ 37,502	$ 1,461,719	$ 95,657
Martin Terminal Acquisition [Member]
Business Acquisition [Line Items]
Net purchase price of acquisition	$ 95,700
Other payments to acquire businesses, capital expenditure requirements included in net purchase price	$ 2,100
Acquired crude storage capacity \| bbl	900,000
Acquired refined product storage capacity \| bbl	250,000

REVENUE FROM CONTRACTS WITH CUSTOMERS Table 1 - Adoption Impact of 606 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	$ 1,961,757	$ 1,814,019	$ 1,756,682
Operating income (loss)	89,968	95,277	79,838	98,480	74,018	91,717	73,404	97,139	363,563	336,278	359,109
Net income (loss)	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	$ 205,794	$ 147,964	$ 150,003
Basic net (loss) income per common unit	$ (0.31)	$ (3.49)	$ 0.15	$ 1.15	$ 0.00	$ 0.15	$ 0.05	$ 0.49	$ (2.77)	$ 0.64	$ 1.27
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Revenue Recognition [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues									$ 1,967,942
Operating income (loss)									369,748
Net income (loss)									$ 211,979
Basic net (loss) income per common unit									$ (2.70)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Revenue Recognition [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues									$ (6,185)
Operating income (loss)									(6,185)
Net income (loss)									$ (6,185)
Basic net (loss) income per common unit									$ (0.07)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

REVENUE FROM CONTRACTS WITH CUSTOMERS Table 2 - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Contract assets
Balance as of January 1, 2018	$ 2,127
Additions	3,281
Transfer to accounts receivable	(2,803)
Total activity	478
Balance as of December 31, 2018	2,605
Less current portion	2,066
Noncurrent portion	539
Contract liabilities
Balance as of January 1, 2018	(60,464)
Additions	(83,243)
Transfer to revenues	57,826
Total activity	25,417
Balance as of December 31, 2018	(85,881)
Less current portion	(46,936)	$ 0
Noncurrent portion	$ (38,945)

REVENUE FROM CONTRACTS WITH CUSTOMERS Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2018
Additions to contract liability			$ 83,243
Revenue recognized due to change in contract liability		$ 9,000
Unnamed Customer [Member]
Additions to contract liability	$ 37,500

REVENUE FROM CONTRACTS WITH CUSTOMERS Table 3 - Expected Timing of Satisfaction of Performance Obligations (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 473,027
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 383,889
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 261,900
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 210,772
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 361,153
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 1,853,693

REVENUE FROM CONTRACTS WITH CUSTOMERS Table 4 - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Lessor revenues									$ 39,800
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	1,961,757	$ 1,814,019	$ 1,756,682
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues									(7,570)	(12,106)	(20,944)
Pipeline Segment
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									611,011	516,288	485,650
Lessor revenues									54	0	0
Revenues									611,065	516,288	485,650
Pipeline Segment \| Crude Oil Pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									248,261	187,874	154,543
Pipeline Segment \| Refined Products and Ammonia Pipelines [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									362,750	328,414	331,107
Storage Segment
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									566,101	577,827	610,042
Lessor revenues									39,849	39,126	0
Revenues									605,950	616,953	610,042
Storage Segment \| Throughput Terminal [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									83,157	85,927	117,586
Storage Segment \| Storage Terminal [Member]
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									482,944	491,900	492,456
Fuels Marketing Segment
Disaggregation of Revenue [Line Items]
Revenues from contracts with customer									$ 752,312	$ 692,884	$ 681,934

ALLOWANCE FOR DOUBTFUL ACCOUNTS Table - Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable Additional Disclosures [Abstract]
Balance as of beginning of year	$ 9,948	$ 7,756	$ 8,473
Increase in allowance, net	755	2,217	24
Accounts charged against the allowance	(1,291)	(25)	(741)
Balance as of end of year	$ 9,412	$ 9,948	$ 7,756

INVENTORIES Table - Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory [Line Items]
Petroleum products	$ 12,689	$ 17,027
Materials and supplies	10,024	9,830
Total	$ 22,713	$ 26,857

PROPERTY, PLANT AND EQUIPMENT Table - Property, Plant and Equipment, at Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 6,338,312	$ 6,243,481
Less accumulated depreciation and amortization	(2,049,690)	(1,942,548)
Property, plant and equipment, net	4,288,622	4,300,933
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	143,477	143,527
Land and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	215,796	203,085
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	160,069	151,702
Pipelines, storage and terminals
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	5,315,201	5,080,795
Rights-of-way
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	301,739	264,170
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 202,030	$ 400,202
Minimum [Member] \| Land and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Minimum [Member] \| Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	15 years
Minimum [Member] \| Pipelines, storage and terminals
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	15 years
Minimum [Member] \| Rights-of-way
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	20 years
Maximum [Member] \| Land and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years
Maximum [Member] \| Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years
Maximum [Member] \| Pipelines, storage and terminals
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years
Maximum [Member] \| Rights-of-way
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years

PROPERTY, PLANT AND EQUIPMENT Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Capitalized interest costs	$ 7.8	$ 5.5	$ 3.4
Depreciation and amortization expense for property, plant and equipment	$ 243.5	$ 222.5	$ 200.7

INTANGIBLE ASSETS Table 1 - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Intangible Assets [Line Items]
Cost	$ 866,309	$ 866,309
Accumulated Amortization	$ (133,253)	(81,830)
Customer relationships
Intangible Assets [Line Items]
Finite-Lived intangible asset, useful life	18 years
Cost	$ 863,950	863,950
Accumulated Amortization	$ (132,509)	(81,136)
Other
Intangible Assets [Line Items]
Finite-Lived intangible asset, useful life	47 years
Cost	$ 2,359	2,359
Accumulated Amortization	$ (744)	$ (694)

INTANGIBLE ASSETS Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization expense	$ 51,400	$ 39,600	$ 13,900
2019	51,000
2020	51,000
2021	51,000
2022	51,000
2023	$ 45,000

GOODWILL Table - Changes in the Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill	$ 1,341,429	$ 1,401,928	$ 1,001,090
Accumulated impairment losses	(304,453)	(304,453)	(304,453)
Navigator Acquisition preliminary purchase price allocation (a)		400,838
Navigator Acquisition purchase price allocation adjustments (a)	(2,814)
Net goodwill	1,036,976	1,097,475	696,637
Pipeline Segment
Goodwill [Roll Forward]
Goodwill	704,231	707,045	306,207
Accumulated impairment losses	0	0	0
Navigator Acquisition preliminary purchase price allocation (a)		400,838
Navigator Acquisition purchase price allocation adjustments (a)	(2,814)
Net goodwill	704,231	707,045	306,207
Storage Segment
Goodwill [Roll Forward]
Goodwill	606,075	663,760	663,760
Accumulated impairment losses	(304,453)	(304,453)	(304,453)
Navigator Acquisition preliminary purchase price allocation (a)		0
Navigator Acquisition purchase price allocation adjustments (a)	0
Net goodwill	301,622	359,307	359,307
Fuels Marketing Segment
Goodwill [Roll Forward]
Goodwill	31,123	31,123	31,123
Accumulated impairment losses	0	0	0
Navigator Acquisition preliminary purchase price allocation (a)		0
Navigator Acquisition purchase price allocation adjustments (a)	0
Net goodwill	31,123	$ 31,123	$ 31,123
U.K. and Amsterdam [Member]
Goodwill [Roll Forward]
Adjustment due to the sale of our European operations (a)	(57,685)
U.K. and Amsterdam [Member] \| Pipeline Segment
Goodwill [Roll Forward]
Adjustment due to the sale of our European operations (a)	0
U.K. and Amsterdam [Member] \| Storage Segment
Goodwill [Roll Forward]
Adjustment due to the sale of our European operations (a)	(57,685)
U.K. and Amsterdam [Member] \| Fuels Marketing Segment
Goodwill [Roll Forward]
Adjustment due to the sale of our European operations (a)	$ 0

ACCRUED LIABILITIES Table - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Employee wages and benefit costs	$ 30,720	$ 16,963
Revenue contract liabilities	46,936	0
Deferred revenue	0	18,243
Other	24,337	26,372
Accrued liabilities	$ 101,993	$ 61,578

DEBT Table 1 - Long-Term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Debt Instrument [Line Items]
Net fair value adjustments, unamortized discounts and unamortized debt issuance costs	$ (12,744)	$ (10,492)
Total long-term debt	3,111,996	3,613,059
Less current portion	0	349,990
Long-term debt, less current portion	3,111,996	$ 3,263,069
Logistics' Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date		Oct. 29, 2020
Total long-term debt	$ 745,000	$ 893,311
7.65% senior notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Apr. 15, 2018
Total long-term debt	$ 0	350,000	$ 350,000
4.80% senior notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Sep. 01, 2020
Total long-term debt	$ 450,000	450,000
6.75% senior notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Feb. 01, 2021
Total long-term debt	$ 300,000	300,000
4.75% senior notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Feb. 01, 2022
Total long-term debt	$ 250,000	250,000
5.625% senior notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Apr. 28, 2027
Total long-term debt	$ 550,000	550,000
Subordinated Notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Jan. 15, 2043
Total long-term debt	$ 402,500	402,500
Gulf Opportunity Zone revenue bonds
Debt Instrument [Line Items]
Maturity date range, start	Jun. 01, 2038
Maturity date range, end	Aug. 01, 2041
Total long-term debt	$ 365,440	365,440
Receivables Financing Agreement
Debt Instrument [Line Items]
Debt instrument, maturity date	Sep. 20, 2020
Total long-term debt	$ 61,800	$ 62,300

DEBT Table 2 - Long-Term Debt Repayments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Long-term Debt, Fiscal Year Maturity [Abstract]
2019	$ 0
2020	1,256,800
2021	300,000
2022	250,000
2023	0
Thereafter	1,317,940
Total repayments	3,124,740
Net fair value adjustments, unamortized discounts and unamortized debt issuance costs	(12,744)	$ (10,492)
Total long-term debt	$ 3,111,996	$ 3,613,059

DEBT Narrative 1 (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
DEBT Narrative 1 (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 28, 2018	Jun. 29, 2018
Debt Instrument [Line Items]
Interest payments		$ 190,900	$ 163,600	$ 146,100
Amortization of debt issuance costs and debt discount		7,100	5,000	$ 4,400
Amount outstanding		3,111,996	3,613,059
Logistics' Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			1,750,000		$ 1,400,000	$ 1,575,000
Maximum available for Euro borrowings		250,000
Maximum available for British Pound Borrowings		$ 250,000
Line of credit facility, covenant terms		a minimum consolidated interest coverage ratio (as defined in the Revolving Credit Agreement), which must not be less than 1.75-to-1.00 for each rolling period of four quarters, beginning with the rolling period ending June 30, 2018; the maximum allowed consolidated debt coverage ratio (as defined in the Revolving Credit Agreement) to 5.25-to-1.00 for the rolling periods ending June 30, 2018 through December 31, 2018. For any rolling periods ending on or after March 31, 2019, the maximum allowed consolidated debt coverage ratio may not exceed 5.00-to-1.00. If we complete one or more acquisitions for aggregate net consideration of at least $50.0 million, our maximum consolidated debt coverage ratio will increase to 5.50-to-1.00 for two rolling periods. The Revolving Credit Agreement also contains customary restrictive covenants, such as limitations on indebtedness, liens, mergers, asset transfers and certain investing activities.
Current remaining borrowing capacity		$ 651,300
Interest rate increase	0.25%
Interest rate at period end		4.50%
Amount outstanding		$ 745,000	$ 893,311
Interest rate during period		4.10%
Letters of credit issued		$ 3,700
Maximum letters of credit allowed		400,000
Line of Credit Facility, Maximum Letters of Credit Available for Euro Borrowings		25,000
Line of Credit Facility, Maximum Letters of Credit Available for British Pound Borrowings		25,000
Debt instrument, maturity date			Oct. 29, 2020
Other long-term assets, net \| Logistics' Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Deferred issuance costs		$ 4,000

DEBT Narrative 2 (Details) - USD ($)			3 Months Ended	12 Months Ended
DEBT Narrative 2 (Details) - USD ($)	Jan. 15, 2018	Apr. 28, 2017	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 15, 2018	Jan. 14, 2018
Debt Instrument [Line Items]
Proceeds from note offering, net of issuance costs				$ 0	$ 543,333,000	$ 0
Amount outstanding				$ 3,111,996,000	3,613,059,000
5.625% senior notes
Debt Instrument [Line Items]
Senior notes issued		$ 550,000,000
Stated interest rate		5.625%		5.625%
Proceeds from note offering, net of issuance costs		$ 543,300,000
Amount outstanding				$ 550,000,000	550,000,000
Debt Instrument, Redemption, Description				If we undergo a change of control, as defined in the supplemental indentures for the 6.75% senior notes or the 5.625% senior notes, each holder of the 6.75% senior notes or the 5.625% senior notes may require us to repurchase all or a portion of its notes at a price equal to 101% of the principal amount of the notes, plus any accrued and unpaid interest to the date of repurchase
Maturity date				Apr. 28, 2027
4.80% senior notes
Debt Instrument [Line Items]
Stated interest rate				4.80%
Amount outstanding				$ 450,000,000	450,000,000
Maturity date				Sep. 01, 2020
6.75% senior notes
Debt Instrument [Line Items]
Stated interest rate				6.75%
Amount outstanding				$ 300,000,000	300,000,000
Debt Instrument, Redemption, Description				If we undergo a change of control, as defined in the supplemental indentures for the 6.75% senior notes or the 5.625% senior notes, each holder of the 6.75% senior notes or the 5.625% senior notes may require us to repurchase all or a portion of its notes at a price equal to 101% of the principal amount of the notes, plus any accrued and unpaid interest to the date of repurchase
Maturity date				Feb. 01, 2021
4.75% senior notes
Debt Instrument [Line Items]
Stated interest rate				4.75%
Amount outstanding				$ 250,000,000	250,000,000
Maturity date				Feb. 01, 2022
7.65% senior notes
Debt Instrument [Line Items]
Stated interest rate							7.65%
Amount outstanding			$ 350,000,000	$ 0	350,000,000
Effective interest rate							8.65%
Interest rate increase			0.25%
Maturity date				Apr. 15, 2018
Subordinated Notes
Debt Instrument [Line Items]
Stated interest rate								7.625%
Amount outstanding				$ 402,500,000	402,500,000
Interest rate terms				an annual rate equal to the sum of the three-month LIBOR for the related quarterly interest period, plus 6.734% payable quarterly, commencing April 15, 2018, unless payment is deferred in accordance with the terms of the notes. NuStar Logistics may elect to defer interest payments on the Subordinated Notes on one or more occasions for up to five consecutive years.
Debt instrument redemption price, percentage	100.00%
Effective interest rate				9.20%
Maturity date				Jan. 15, 2043
Gulf Opportunity Zone revenue bonds
Debt Instrument [Line Items]
Amount outstanding				$ 365,440,000	365,440,000
Amount Received From Trustee				$ 0	$ 0

DEBT Table 3 - GoZone Bonds (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Amount outstanding	$ 3,111,996	$ 3,613,059
Go Zone Bonds Due June 2038
Debt Instrument [Line Items]
Date Issued	Jun. 26, 2008
Maturity date	Jun. 01, 2038
Amount outstanding	$ 55,440
Amount of Letter of Credit	56,169
Amount Received From Trustee	55,440
Amount Remaining in Trust	$ 0
Weighted average annual interest rate	1.80%
Go Zone Bonds Due July 2040
Debt Instrument [Line Items]
Date Issued	Jul. 15, 2010
Maturity date	Jul. 01, 2040
Amount outstanding	$ 100,000
Amount of Letter of Credit	101,315
Amount Received From Trustee	100,000
Amount Remaining in Trust	$ 0
Weighted average annual interest rate	1.80%
Go Zone Bonds Due October 2040
Debt Instrument [Line Items]
Date Issued	Oct. 07, 2010
Maturity date	Oct. 01, 2040
Amount outstanding	$ 50,000
Amount of Letter of Credit	50,658
Amount Received From Trustee	43,741
Amount Remaining in Trust	$ 6,596
Weighted average annual interest rate	1.80%
Go Zone Bonds Due December 2040
Debt Instrument [Line Items]
Date Issued	Dec. 29, 2010
Maturity date	Dec. 01, 2040
Amount outstanding	$ 85,000
Amount of Letter of Credit	86,118
Amount Received From Trustee	49,782
Amount Remaining in Trust	$ 36,271
Weighted average annual interest rate	1.80%
Go Zone Bonds Due August 2041
Debt Instrument [Line Items]
Date Issued	Aug. 29, 2011
Maturity date	Aug. 01, 2041
Amount outstanding	$ 75,000
Amount of Letter of Credit	75,986
Amount Received From Trustee	75,000
Amount Remaining in Trust	$ 0
Weighted average annual interest rate	1.80%
Total Gulf Opportunity Zone revenue bonds
Debt Instrument [Line Items]
Amount outstanding	$ 365,440	$ 365,440
Amount of Letter of Credit	370,246
Amount Received From Trustee	323,963
Amount Remaining in Trust	$ 42,867
Debt, Weighted Average Interest Rate	1.40%

DEBT Narrative 3 (Details) - USD ($) $ in Thousands	12 Months Ended
DEBT Narrative 3 (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Short-term debt	$ 18,500	$ 35,000
Receivables Financing Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 125,000
Line of Credit Facility, Borrowing Capacity, Description	The March 28, 2018 amendment to the Revolving Credit Agreement also limits the amount of borrowings by NuStar Finance under the Receivables Financing Agreement to $125.0 million. The amount available for borrowing is based on the availability of eligible receivables and other customary factors and conditions.
Debt Instrument, Maturity Date, Description	On September 20, 2017, the Securitization Program was amended to add certain of NuStar Energy’s wholly owned subsidiaries resulting from the Navigator Acquisition and to extend the Securitization Program’s scheduled termination date from June 15, 2018 to September 20, 2020, with the option to renew for additional 364-day periods thereafter.
Debt Instrument, Collateral Amount	$ 95,500	$ 92,600
Weighted average annual interest rate	3.00%
Short-term line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 35,000
Short-term debt	$ 18,500
Weighted average annual interest rate	4.40%	3.20%

HEALTH, SAFETY AND ENVIRONMENTAL MATTERS Table 1 - Balance of and Changes in Accruals for Environmental Matters (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance as of the beginning of year	$ 5,683	$ 5,120
Additions to accrual	5,160	3,186
Payments	(3,058)	(2,675)
Foreign currency translation	(32)	52
Balance as of the end of year	$ 7,753	$ 5,683

HEALTH, SAFETY AND ENVIRONMENTAL MATTERS Table 2 - Accruals for Environmental Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accrual for Environmental Loss Contingencies, Balance Sheet Classification [Abstract]
Accrued liabilities	$ 4,349	$ 3,054
Other long-term liabilities	3,404	2,629
Accruals for environmental matters	$ 7,753	$ 5,683	$ 5,120

COMMITMENTS AND CONTINGENCIES Narrative 1 (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Loss contingency accrual, at carrying value	$ 2.8	$ 7.3

COMMITMENTS AND CONTINGENCIES Table - Commitments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Operating Leases (Lessee)
2019	$ 34,900
2020	20,787
2021	14,904
2022	9,280
2023	6,870
Thereafter	28,552
Total	115,293
Purchase Obligations
2019	10,896
2020	7,958
2021	7,011
2022	4,970
2023	602
Thereafter	2,624
Total	$ 34,061

COMMITMENTS AND CONTINGENCIES Narrative 2 - Lessee Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Major Operating Leases
Rent expense for operating leases (lessee)	$ 42.9	$ 36.2	$ 37.0
Description of purchase obligations	Our purchase obligations primarily consist of an eleven-year chemical supply agreement related to our pipelines.
St Eustatius Tugs and Barges [Member]
Major Operating Leases
Description of leasing arrangements for operating leases (lessee)	two leases for tugs and barges utilized at our St. Eustatius facility for bunker fuel sales, with original terms of nine and ten years
Land Leases [Member]
Major Operating Leases
Description of leasing arrangements for operating leases (lessee)	land and dock leases at various terminal facilities, with original terms generally ranging from 5 to 40 years, including a build-to-suit lease with an initial term of five years and four additional five-year renewal periods that also includes a commitment for minimum dockage and wharfage throughput volumes.

COMMITMENTS AND CONTINGENCIES Narrative 3 - Lessor Revenues (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Lessor leasing arrangements, operating leases, term of contract	10 years
Lessor leasing arrangements, operating leases, renewal term	10 years
Operating lease revenues	$ 39.8
Future minimum revenue (lessor)	$ 313.1
Lessor leasing arrangements, operating leases, remaining term of contract	8 years
Leased storage assets, cost	$ 233.2
Leased storage assets, accumulated depreciation	$ 113.1

FAIR VALUE MEASUREMENTS Table 1 - Recurring Fair Value Measurements (Details) - Recurring Fair Value Measurements - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Total (assets)	$ 757
Liabilities:
Total (liabilities)		$ (12,400)
Level 1 [Member]
Assets:
Total (assets)	130
Liabilities:
Total (liabilities)		(2,412)
Level 2 [Member]
Assets:
Total (assets)	627
Liabilities:
Total (liabilities)		(9,988)
Level 3 [Member]
Assets:
Total (assets)	0
Liabilities:
Total (liabilities)		0
Other current assets
Assets:
Product imbalances - asset		3,890
Commodity derivatives - asset	130
Other current assets \| Level 1 [Member]
Assets:
Product imbalances - asset		3,890
Commodity derivatives - asset	130
Other current assets \| Level 2 [Member]
Assets:
Product imbalances - asset		0
Commodity derivatives - asset	0
Other current assets \| Level 3 [Member]
Assets:
Product imbalances - asset		0
Commodity derivatives - asset	0
Other long-term assets, net
Assets:
Interest rate swaps - asset	627
Other long-term assets, net \| Level 1 [Member]
Assets:
Interest rate swaps - asset	0
Other long-term assets, net \| Level 2 [Member]
Assets:
Interest rate swaps - asset	627
Other long-term assets, net \| Level 3 [Member]
Assets:
Interest rate swaps - asset	0
Accrued liabilities
Liabilities:
Product imbalances - liability		(1,534)
Commodity derivatives - liability		(878)
Interest rate swaps - liability		(5,394)
Accrued liabilities \| Level 1 [Member]
Liabilities:
Product imbalances - liability		(1,534)
Commodity derivatives - liability		(878)
Interest rate swaps - liability		0
Accrued liabilities \| Level 2 [Member]
Liabilities:
Product imbalances - liability		0
Commodity derivatives - liability		0
Interest rate swaps - liability		(5,394)
Accrued liabilities \| Level 3 [Member]
Liabilities:
Product imbalances - liability		0
Commodity derivatives - liability		0
Interest rate swaps - liability		0
Other long-term liabilities
Liabilities:
Interest rate swaps - liability	(751)	(4,594)
Other long-term liabilities \| Level 1 [Member]
Liabilities:
Interest rate swaps - liability	0	0
Other long-term liabilities \| Level 2 [Member]
Liabilities:
Interest rate swaps - liability	(751)	(4,594)
Other long-term liabilities \| Level 3 [Member]
Liabilities:
Interest rate swaps - liability	$ 0	$ 0

FAIR VALUE MEASUREMENTS Table 2 - Fair Value and Carrying Amounts of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair value, long-term debt, including current portion	$ 3,056,704	$ 3,677,622
Carrying amount, long-term debt, including current portion	$ 3,111,996	$ 3,613,059

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES Narrative (Details) bbl in Millions			1 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) bbl	Dec. 31, 2017 USD ($) bbl	Apr. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Apr. 15, 2018
Derivative [Line Items]
Cash received from termination of interest rate swaps			$ 8,000,000
Number of forecasted interest payments probable not to occur				2
Loss due to forecasted interest payment probable not to occur				$ 400,000
Interest rate swaps
Derivative [Line Items]
Fair market value of unwound fixed-to-floating interest rate swap	$ 10,500,000	$ 15,600,000		10,500,000	$ 10,500,000
Fair market value of unwound forward starting interest rate swap	800,000	14,300,000		800,000	$ 800,000
Interest rate swaps \| Cash Flow Hedges
Derivative [Line Items]
Interest rate swaps interest rate received					receive a rate based on the three-month USD LIBOR
Notional amount of interest rate swaps	$ 250,000,000.0	$ 600,000,000.0		250,000,000.0	$ 250,000,000.0
Notional amount of forward starting interest rate swaps terminated			$ 350,000,000.0
Commodity contracts
Derivative [Line Items]
Notional amount of commodity contracts, in barrels \| bbl	0.7	1.2
Margin deposit assets	$ 0	$ 300,000		$ 0	$ 0
7.65% senior notes
Derivative [Line Items]
Stated interest rate						7.65%

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES Table 1 - Fair Values of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value
Asset Derivatives	$ 2,388	$ 742
Liability Derivatives	(2,382)	(11,608)
Designated as Hedging Instrument
Derivatives, Fair Value
Asset Derivatives	736	0
Liability Derivatives	(751)	(10,100)
Designated as Hedging Instrument \| Commodity contracts \| Other current assets
Derivatives, Fair Value
Asset Derivatives	109	0
Liability Derivatives	0	0
Designated as Hedging Instrument \| Commodity contracts \| Accrued liabilities
Derivatives, Fair Value
Asset Derivatives	0	0
Liability Derivatives	0	(112)
Designated as Hedging Instrument \| Interest rate swaps \| Other long-term assets, net
Derivatives, Fair Value
Asset Derivatives	627	0
Liability Derivatives	0	0
Designated as Hedging Instrument \| Interest rate swaps \| Accrued liabilities
Derivatives, Fair Value
Asset Derivatives	0	0
Liability Derivatives	0	(5,394)
Designated as Hedging Instrument \| Interest rate swaps \| Other long-term liabilities
Derivatives, Fair Value
Asset Derivatives	0	0
Liability Derivatives	(751)	(4,594)
Not Designated as Hedging Instrument
Derivatives, Fair Value
Asset Derivatives	1,652	742
Liability Derivatives	(1,631)	(1,508)
Not Designated as Hedging Instrument \| Commodity contracts \| Other current assets
Derivatives, Fair Value
Asset Derivatives	1,652	0
Liability Derivatives	(1,631)	0
Not Designated as Hedging Instrument \| Commodity contracts \| Accrued liabilities
Derivatives, Fair Value
Asset Derivatives	0	742
Liability Derivatives	$ 0	$ (1,508)

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES Table 2 - Derivative Instruments Eligble for Offset (Details) - Commodity contracts - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets [Line Items]
Net amounts of assets presented in the consolidated balance sheets	$ 130	$ 0
Net amounts of liabilities presented in the consolidated balance sheets	$ 0	$ (878)

DERIVATIVES AND RISK MANAGEMENT ACTIVITIES Table 3 - Impact of Derivatives on Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss)
Gain (loss) to be reclassified during next 12 months, forward starting interest rate swaps	$ 3,500
Designated as Hedging Instrument \| Fair Value Hedges \| Commodity contracts \| Cost of product sales
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income on derivative	(535)	$ 806	$ (11,254)
Gain (loss) recognized in income on hedged item	(181)	(656)	15,295
Gain (loss) recognized in income for ineffective portion	(716)	150	4,041
Designated as Hedging Instrument \| Cash Flow Hedges \| Interest rate swaps \| Other comprehensive income (loss)
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in other comprehensive income (loss) on derivative (effective portion)	17,912	(8,670)	(2,621)
Designated as Hedging Instrument \| Cash Flow Hedges \| Interest rate swaps \| Interest expense, net
Derivative Instruments, Gain (Loss)
Gain (loss) reclassified from AOCI into interest expense, net (effective portion)	(5,499)	(6,624)	(8,331)
Not Designated as Hedging Instrument \| Commodity contracts \| Cost of product sales
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income on derivative	$ (601)	$ (668)	$ 225

OTHER INCOME (EXPENSE) Table - Other Income (Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Income and Expenses [Abstract]
Gain (loss) related to hurricane activity	$ 78,756	$ (5,000)	$ 0
Impairment loss on Axeon Term Loan	0	0	(58,655)
Loss on sale of European operations	(43,366)	0	0
Other, net	4,486	(294)	(128)
Other (expense) income, net	$ 39,876	$ (5,294)	$ (58,783)

OTHER INCOME (EXPENSE) Narrative 1 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unusual or Infrequent Item, or Both [Line Items]
Gain (loss) related to hurricane activity	$ 78,756	$ (5,000)	$ 0
Other Nonoperating Income (Expense) [Member]
Unusual or Infrequent Item, or Both [Line Items]
Gain (loss) related to hurricane activity	$ 78,800	$ (5,000)

OTHER INCOME (EXPENSE) Narrative 2 (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Feb. 22, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Cash collection on Axeon Term Loan			$ 0	$ 110,000	$ 0
Impairment loss on Axeon Term Loan			$ 0	$ 0	58,655
Axeon [Member]
Financing Receivable, Impaired [Line Items]
Cash collection on Axeon Term Loan	$ 110,000
Impairment loss on Axeon Term Loan		$ 58,700
Carrying amount, Axeon Term Loan		$ 110,000			$ 110,000

OTHER INCOME (EXPENSE) Narrative 3 (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of European operations		$ 266,740	$ 0	$ 0
Non-cash loss on sale of assets		(43,366)	$ 0	$ 0
Sale of U.K. and Amsterdam Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of European operations	$ 270,000
Description of assets sold	six liquids storage terminals in the United Kingdom and one facility in Amsterdam
Other Nonoperating Income (Expense) [Member] \| Sale of U.K. and Amsterdam Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-cash loss on sale of assets		$ (43,400)

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS Narrative 1 (Details) - USD ($) $ / shares in Units, $ in Thousands			9 Months Ended	12 Months Ended
	Jul. 13, 2018	Jun. 29, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Proceeds from issuance of Series D preferred units				$ 590,000	$ 0	$ 0
Series D preferred units outstanding				23,246,650	0
Net proceeds from issuance of Series D preferred units				$ 555,797
Series D Preferred Limited Partner [Member]
Class of Stock [Line Items]
Proceeds from issuance of Series D preferred units	$ 190,000	$ 400,000	$ 590,000
Series D preferred units outstanding			23,246,650
Units issued, price per unit	$ 25.38	$ 25.38
Issuance of preferred units (temporary equity) (in units)	7,486,209	15,760,441
Net proceeds from issuance of Series D preferred units		$ 370,700	$ 555,800	$ 555,797
Transaction fee percentage			3.50%
Transaction fee			$ 20,700
Equity issuance costs			$ 13,500

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS Narrative 2 (Details) - Series D Preferred Limited Partner [Member] $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares
Class of Stock [Line Items]
Unpaid dividend penalty, per unit dividend increase	$ 0.048
Unpaid dividend penalty, preferred stock, conversion basis	if we fail to pay in full any Series D Preferred Unit distribution amount for three consecutive distribution periods, then until we pay such distributions in full: (i) each holder of the Series D Preferred Units may elect to convert its Series D Preferred Units into common units on a one-for-one basis, plus any unpaid Series D distributions
Unpaid dividend penalty, minimum amount of acquisitions or asset sales requiring consent \| $	$ 50.0
Preferred Stock, Distributions, Period - June 29, 2018 to June 28, 2020 [Member]
Class of Stock [Line Items]
Preferred units distribution percentage	9.75%
Preferred Stock, Distributions, Period - June 29, 2020 to June 28, 2023 [Member]
Class of Stock [Line Items]
Preferred units distribution percentage	10.75%
Preferred Stock, Distributions, Period - June 29, 2023 and thereafter [Member]
Class of Stock [Line Items]
Preferred unit, distribution payment rate, variable description	the greater of 13.75% per annum or the distribution per common unit thereafter
Preferred Stock, Distributions, Period - June 29, 2018 to June 15, 2019 [Member]
Class of Stock [Line Items]
Maximum percentage of distributions that may be paid in additional units	50.00%
Preferred Stock Distributions, Period - June 16, 2019 and thereafter [Member]
Class of Stock [Line Items]
Required amount of per unit cash dividends to permit dividend paid in kind	$ 0.635
Minimum [Member] \| Preferred Stock, Distributions, Period - June 29, 2023 and thereafter [Member]
Class of Stock [Line Items]
Preferred units distribution percentage	13.75%

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS Table - Cash Distributions - Series D Preferred Units (Details) - Series D Preferred Limited Partner [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 13, 2018	Jun. 29, 2018
Class of Stock [Line Items]
Preferred unit distribution paid		$ 0.619
Cash distributions applicable to preferred limited partners		$ 14,390		$ 28,449	$ 0	$ 0
Distribution date of record		Dec. 03, 2018	Sep. 04, 2018
Distribution payment date, preferred units		Dec. 17, 2018	Sep. 17, 2018
Issuance of preferred units (temporary equity) (in units)							7,486,209	15,760,441
Subsequent Event [Member]
Class of Stock [Line Items]
Preferred unit distribution declared	$ 0.619
Cash distributions applicable to preferred limited partners	$ 14,390
Distribution date of record	Mar. 01, 2019
Distribution payment date, preferred units	Mar. 15, 2019
Equity Issuance Date, July 13, 2018 [Member]
Class of Stock [Line Items]
Preferred unit distribution paid			$ 0.431
Cash distributions applicable to preferred limited partners			$ 3,227
Equity Issuance Date, June 29, 2018 [Member]
Class of Stock [Line Items]
Preferred unit distribution paid			$ 0.525
Cash distributions applicable to preferred limited partners			$ 8,274

SERIES D CUMULATIVE CONVERTIBLE PREFERRED UNITS Narrative 3 (Details) - Series D Preferred Limited Partner [Member] - USD ($) $ in Millions		12 Months Ended
	Jul. 20, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Convertible preferred units, terms of redemption		The Partnership may redeem all or any portion of the Series D Preferred Units, in an amount not less than $50.0 million for cash at a redemption price equal to, as applicable: (i) $31.73 per Series D Preferred Unit at any time on or after June 29, 2023 but prior to June 29, 2024; (ii) $30.46 per Series D Preferred Unit at any time on or after June 29, 2024 but prior to June 29, 2025; (iii) $29.19 per Series D Preferred Unit at any time on or after June 29, 2025; plus, in each case, the sum of any unpaid distributions on the applicable Series D Preferred Unit plus the distributions prorated for the number of days elapsed (not to exceed 90) in the period of redemption (Series D Partial Period Distributions). The holders have the option to convert the units prior to such redemption as discussed above. Additionally, at any time on or after June 29, 2028, each holder of Series D Preferred Units will have the right to require the Partnership to redeem all of the Series D Preferred Units held by such holder at a redemption price equal to $29.19 per Series D Preferred Unit plus any unpaid Series D distributions plus the Series D Partial Period Distributions. If a holder of Series D Preferred Units exercises its redemption right, the Partnership may elect to pay up to 50% of such amount in common units (which shall be valued at 93% of a volume-weighted average trading price of the common units); provided, that the common units to be issued do not, in the aggregate, exceed 15% of NuStar Energy’s common equity market capitalization at the time.
Maximum number of days within a partial distribution period		90
Convertible preferred units, terms of conversion, change of control		convert its Series D Preferred Units into common units on a one-for-one basis, plus any unpaid Series D distributions
Change of control redemption amount		the sum of (a) $29.82 per Series D Preferred Unit plus (b) any unpaid Series D distributions plus (c) the applicable distribution amount for the distribution periods ending after the change of control event and prior to (but including) the fourth anniversary of the Initial Closing
Temporary equity, accounting treatment		The Series D Preferred Units include redemption provisions at the option of the holders of the Series D Preferred Units and upon a Series D Change of Control (as defined in the partnership agreement), which are outside the Partnership’s control. Therefore, the Series D Preferred Units are presented in the mezzanine section of the consolidated balance sheets. The Series D Preferred Units have been recorded at their issuance date fair value, net of issuance costs. We reassess the presentation of the Series D Preferred Units in our consolidated balance sheets on a quarterly basis. The Series D Preferred Units are subject to accretion from their carrying value at the issuance date to the redemption value, which is based on the redemption right of the Series D Preferred Unit holders that may be exercised at any time on or after June 29, 2028, using the effective interest method over a period of ten years. In the calculation of net income per unit, the accretion is treated in the same manner as a distribution and deducted from net income to arrive at net income attributable to common units.
Accretion period	10 years
Preferred Stock, Conversion, Period - June 29, 2020 and thereafter [Member]
Class of Stock [Line Items]
Convertible preferred units, terms of conversion		At any time on or after June 29, 2020, each holder of Series D Preferred Units may convert all or any portion of its Series D Preferred Units into common units on a one-for-one basis (plus any unpaid Series D distributions), subject to anti-dilution adjustments, at any time, but not more than once per quarter, so long as any conversion is for at least $50.0 million based on the Series D Preferred Unit Purchase Price (or such lesser amount representing all of a holder’s Series D Preferred Units).
Minimum conversion amount		$ 50.0
Preferred Stock, Issuer Redemption Option, Period - June 29, 2023 to June 28, 2024 [Member]
Class of Stock [Line Items]
Temporary equity redemption price per unit		$31.73 per Series D Preferred Unit plus any unpaid Series D distributions plus the Series D Partial Period Distributions
Preferred Stock, Issuer Redemption Option, Period - June 29, 2023 and thereafter [Member]
Class of Stock [Line Items]
Minimum redemption amount		$ 50.0
Preferred Stock, Holder Redemption Option, Period - June 29, 2028 and thereafter [Member]
Class of Stock [Line Items]
Temporary equity redemption price per unit		$29.19 per Series D Preferred Unit plus any unpaid Series D distributions plus the Series D Partial Period Distributions
Percentage of redemption amount that may be paid in common limited partner units		50.00%
Volume-weighted average trading price percentage of common limited partner units		93.00%
Common limited partners' equity market capitalization, maximum allowable percentage		15.00%
Preferred Stock, Issuer Redemption Option, Period - June 29, 2024 to June 28, 2025 [Member]
Class of Stock [Line Items]
Temporary equity redemption price per unit		$30.46 per Series D Preferred Unit plus any unpaid Series D distributions plus the Series D Partial Period Distributions
Preferred Stock, Issuer Redemption Option, Period - June 29, 2025 and thereafter [Member]
Class of Stock [Line Items]
Temporary equity redemption price per unit		$29.19 per Series D Preferred Unit plus any unpaid Series D distributions plus the Series D Partial Period Distributions

PARTNERS' EQUITY Narrative 1 (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Partners' Capital Notes [Abstract]
General partner ownership interest		2.00%	2.00%	2.00%
Incentive distribution waiver	$ 22.0

PARTNERS' EQUITY Table 1 - Preferred Units (Details) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Nov. 30, 2017	Apr. 28, 2017	Nov. 25, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Net proceeds from issuance of units				$ 10,204	$ 657,475	$ 28,285
Series A Preferred Limited Partner [Member]
Class of Stock [Line Items]
Issuance of units (units)			9,060,000
Units issued, price per unit			$ 25.00
Net proceeds from issuance of units			$ 218,400
Preferred units liquidation preference			$ 25.00
Preferred units distribution percentage, fixed			8.50%
Per unit distribution, fixed, per annum			$ 2.125
Preferred unit, distribution payment rate, variable description			Three-month LIBOR plus 6.766%
Preferred units, description			We may redeem any of our outstanding Series A, B and C Preferred Units at any time on or after the optional redemption date set forth above for each series of the Series A, B and C Preferred Units, in whole or in part, at a redemption price of $25.00 per unit plus an amount equal to all accumulated and unpaid distributions to, but not including, the date of redemption, whether or not declared. We may also redeem the Series A, B and C Preferred Units upon the occurrence of certain rating events or a change of control as defined in our partnership agreement. In the case of the latter instance, if we choose not to redeem the Series A, B and C Preferred Units, those preferred unitholders may have the ability to convert their Series A, B and C Preferred Units to common units at the then applicable conversion rate. Holders of the Series A, B and C Preferred Units have no voting rights except for certain exceptions set forth in our partnership agreement.
Series B Preferred Limited Partner [Member]
Class of Stock [Line Items]
Issuance of units (units)		15,400,000
Units issued, price per unit		$ 25.00
Net proceeds from issuance of units		$ 371,800
Preferred units liquidation preference		$ 25.00
Preferred units distribution percentage, fixed		7.625%
Per unit distribution, fixed, per annum		$ 1.90625
Preferred unit, distribution payment rate, variable description		Three-month LIBOR plus 5.643%
Preferred units, description		We may redeem any of our outstanding Series A, B and C Preferred Units at any time on or after the optional redemption date set forth above for each series of the Series A, B and C Preferred Units, in whole or in part, at a redemption price of $25.00 per unit plus an amount equal to all accumulated and unpaid distributions to, but not including, the date of redemption, whether or not declared. We may also redeem the Series A, B and C Preferred Units upon the occurrence of certain rating events or a change of control as defined in our partnership agreement. In the case of the latter instance, if we choose not to redeem the Series A, B and C Preferred Units, the preferred unitholders may have the ability to convert their Series A, B and C Preferred Units to common units at the then applicable conversion rate. Holders of the Series A, B and C Preferred Units have no voting rights except for certain exceptions set forth in our partnership agreement.
Series C Preferred Limited Partner [Member]
Class of Stock [Line Items]
Issuance of units (units)	6,900,000
Units issued, price per unit	$ 25.00
Net proceeds from issuance of units	$ 166,700
Preferred units liquidation preference	$ 25.00
Preferred units distribution percentage, fixed	9.00%
Per unit distribution, fixed, per annum	$ 2.25
Preferred unit, distribution payment rate, variable description	Three-month LIBOR plus 6.88%
Preferred units, description	We may redeem any of our outstanding Series A, B and C Preferred Units at any time on or after the optional redemption date set forth above for each series of the Series A, B and C Preferred Units, in whole or in part, at a redemption price of $25.00 per unit plus an amount equal to all accumulated and unpaid distributions to, but not including, the date of redemption, whether or not declared. We may also redeem the Series A, B and C Preferred Units upon the occurrence of certain rating events or a change of control as defined in our partnership agreement. In the case of the latter instance, if we choose not to redeem the Series A, B and C Preferred Units, the preferred unitholders may have the ability to convert their Series A, B and C Preferred Units to common units at the then applicable conversion rate. Holders of the Series A, B and C Preferred Units have no voting rights except for certain exceptions set forth in our partnership agreement.

PARTNERS' EQUITY Table 2 - Preferred Partners' Equity (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Preferred limited partners capital, beginning balance				$ 756,603					$ 756,603
Net proceeds from issuance of units									10,204	$ 657,475	$ 28,285
Net income (loss)	$ 2,126	$ 48,136	$ 29,399	126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	205,794	147,964	150,003
Distributions to partners									(364,868)	(486,754)	(394,887)
Other									(6,846)	(679)
Preferred limited partners capital, ending balance	756,301				756,603				756,301	756,603
Series A Preferred Limited Partner [Member]
Preferred limited partners capital, beginning balance				218,307				218,400	218,307	218,400	0
Net proceeds from issuance of units										0	218,400
Net income (loss)									19,253	19,253	1,925
Distributions to partners									(19,253)	(19,253)	(1,925)
Other									0	(93)
Preferred limited partners capital, ending balance	218,307				218,307				218,307	218,307	218,400
Series B Preferred Limited Partner [Member]
Preferred limited partners capital, beginning balance				371,634				0	371,634	0	0
Net proceeds from issuance of units										371,823	0
Net income (loss)									29,357	19,815	0
Distributions to partners									(29,357)	(19,815)	0
Other									(158)	(189)
Preferred limited partners capital, ending balance	371,476				371,634				371,476	371,634	0
Series C Preferred Limited Partner [Member]
Preferred limited partners capital, beginning balance				166,662				0	166,662	0	0
Net proceeds from issuance of units										166,737	0
Net income (loss)									15,481	1,380	0
Distributions to partners									(15,481)	(1,380)	0
Other									(144)	(75)
Preferred limited partners capital, ending balance	166,518				166,662				166,518	166,662	0
Preferred Limited Partner [Member]
Preferred limited partners capital, beginning balance				$ 756,603				$ 218,400	756,603	218,400	0
Net proceeds from issuance of units									0	538,560	218,400
Net income (loss)									64,091	40,448	1,925
Distributions to partners									(64,091)	(40,448)	(1,925)
Other									(302)	(357)
Preferred limited partners capital, ending balance	$ 756,301				$ 756,603				$ 756,301	$ 756,603	$ 218,400

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

PARTNERS' EQUITY Table 3 - Cash Distributions Declared - Preferred Units (Details) - $ / shares	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Series A Preferred Limited Partner [Member]
Distribution Made to Limited Partner [Line Items]
Preferred unit distribution paid		$ 0.53125	$ 0.53125	$ 0.53125	$ 0.53125
Series A Preferred Limited Partner [Member] \| Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Preferred unit distribution declared	$ 0.53125
Series B Preferred Limited Partner [Member]
Distribution Made to Limited Partner [Line Items]
Preferred unit distribution paid		0.47657	0.47657	0.47657	0.47657
Series B Preferred Limited Partner [Member] \| Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Preferred unit distribution declared	0.47657
Series C Preferred Limited Partner [Member]
Distribution Made to Limited Partner [Line Items]
Preferred unit distribution paid		$ 0.56250	$ 0.56250	$ 0.56250	$ 0.65625
Series C Preferred Limited Partner [Member] \| Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Preferred unit distribution declared	$ 0.56250

PARTNERS' EQUITY Narrative 2 (Details) $ / shares in Units, $ in Thousands			3 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Jun. 29, 2018 USD ($) $ / shares shares	Apr. 18, 2017 USD ($) $ / shares shares	Sep. 30, 2018 shares	Jun. 30, 2018	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) $ / shares shares
Class of Stock [Line Items]
Contributions from general partner							$ 204	$ 13,737	$ 680
General partner ownership interest				2.00%				2.00%	2.00%
Percent of available cash distributed							100.00%
Number of days within which distribution is paid to common unitholders and was paid to general partner							45
Distributions to partners							$ 364,868	$ 486,754	$ 394,887
Common Limited Partner [Member]
Class of Stock [Line Items]
Issuance of NuStar Energy common units as a result of the Merger, incremental units issued \| shares			13,400,000
Issuance of units (units) \| shares	413,736	14,375,000							595,050
Units issued, price per unit \| $ / shares	$ 24.17	$ 46.35
Proceeds from common unit issuance including general partner contribution	$ 10,200	$ 657,500							$ 28,300
Weighted average price per unit issued \| $ / shares									$ 47.39
Equity issuance costs									$ 500
Unit-based compensation (units) \| shares							225,144	185,455	135,100
Distributions to partners							$ 286,398	$ 391,737	$ 341,798
General Partner [Member]
Class of Stock [Line Items]
Contributions from general partner		$ 13,600				$ 200			600
General partner ownership interest				2.00%
Distributions to partners					$ 0		$ 14,379	$ 54,569	$ 51,164

PARTNERS' EQUITY Table 4 - General Partner Incentive Distributions (Details)	6 Months Ended
	Jun. 30, 2018
Common Limited Partner [Member] \| Quarterly Distributions Level 1 [Member]
Distribution Allocation [Line Items]
Quarterly distribution amount per common unit	Up to $0.60
Percentage of distribution allocated to common unitholders	98.00%
Common Limited Partner [Member] \| Quarterly Distributions Level 2 [Member]
Distribution Allocation [Line Items]
Quarterly distribution amount per common unit	Above $0.60 up to $0.66
Percentage of distribution allocated to common unitholders	90.00%
Common Limited Partner [Member] \| Quarterly Distributions Level 3 [Member]
Distribution Allocation [Line Items]
Quarterly distribution amount per common unit	Above $0.66
Percentage of distribution allocated to common unitholders	75.00%
General Partner [Member] \| Quarterly Distributions Level 1 [Member]
Distribution Allocation [Line Items]
Percentage of distribution allocated to the general partner	2.00%
General Partner [Member] \| Quarterly Distributions Level 2 [Member]
Distribution Allocation [Line Items]
Percentage of distribution allocated to the general partner	10.00%
General Partner [Member] \| Quarterly Distributions Level 3 [Member]
Distribution Allocation [Line Items]
Percentage of distribution allocated to the general partner	25.00%

PARTNERS' EQUITY Table 5 - Cash Distributions Earned - General and Common Limited Partners (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Distributions Made to Limited Partners and General Partner [Line Items]
General partner interest									$ 1,141	$ 9,252	$ 7,877
General partner incentive distribution									0	45,669	43,407
Total general partner distributions									1,141	54,921	51,284
Common limited partners' distribution									248,705	407,681	342,598
Total cash distributions applicable to common unitbolders and general partner (distribution earned)				$ 57,057					$ 249,846	$ 462,602	$ 393,882
Common Limited Partner [Member]
Distributions Made to Limited Partners and General Partner [Line Items]
Cash distributions per unit applicable to limited partners	$ 0.60	$ 0.60	$ 0.60	$ 0.60	$ 1.095	$ 1.095	$ 1.095	$ 1.095	$ 2.40	$ 4.380	$ 4.380

PARTNERS' EQUITY Table 6 - Cash Distributions Declared - General Partner and Common Limited Partners (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Distribution Made to Limited Partner [Line Items]
Cash distributions applicable to common unitholders (distribution earned)	$ 64,336	$ 64,248	$ 64,205
Cash distributions applicable to common unitbolders and general partner (distribution earned)				$ 57,057					$ 249,846	$ 462,602	$ 393,882
Common Limited Partner [Member]
Distribution Made to Limited Partner [Line Items]
Cash distributions per unit applicable to limited partners	$ 0.60	$ 0.60	$ 0.60	$ 0.60	$ 1.095	$ 1.095	$ 1.095	$ 1.095	$ 2.40	$ 4.380	$ 4.380
Distribution date of record (distribution earned)	Feb. 08, 2019	Nov. 08, 2018	Aug. 07, 2018	May 08, 2018
Distribution payment date	Feb. 13, 2019	Nov. 14, 2018	Aug. 13, 2018	May 14, 2018

PARTNERS' EQUITY Table 7 - Net Income Applicable to the General Partner (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Income Allocation [Abstract]
Net income (loss)	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940		$ 205,794	$ 147,964	$ 150,003
Less preferred limited partner interest										92,540	40,448	1,925
Less general partner incentive distribution										0	45,669	43,407
Net income (loss) after general partner incentive distribution and preferred limited partner interest											$ 61,847	$ 104,671
General partner interest									2.00%		2.00%	2.00%
General partner allocation of net income (loss)											$ 1,237	$ 2,091
General partner incentive distribution										0	45,669	43,407
Net income applicable to general partner										$ 2,500	$ 46,906	$ 45,498

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

PARTNERS' EQUITY Table 8 - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (84,927)
Other comprehensive income (loss)	30,049	$ 9,250	$ (5,383)
Ending balance	(54,878)	(84,927)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(51,603)	(69,069)	(60,826)
Employee Transfer			0
Deferred income tax adjustments			0
Other comprehensive income (loss) before reclassifications	(13,880)	17,466	(8,243)
Other	60
Other comprehensive income (loss)	4,304	17,466	(8,243)
Ending balance	(47,299)	(51,603)	(69,069)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(24,304)	(22,258)	(27,968)
Employee Transfer			0
Deferred income tax adjustments			0
Other comprehensive income (loss) before reclassifications	17,912	(8,670)	(2,621)
Other	0
Other comprehensive income (loss)	23,411	(2,046)	5,710
Ending balance	(893)	(24,304)	(22,258)
Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(9,020)	(2,850)	0
Employee Transfer			4,201
Deferred income tax adjustments			2,414
Other comprehensive income (loss) before reclassifications	3,282	(4,641)	(7,852)
Other	(134)
Other comprehensive income (loss)	2,334	(6,170)	(2,850)
Ending balance	(6,686)	(9,020)	(2,850)
Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(84,927)	(94,177)	(88,794)
Employee Transfer			4,201
Deferred income tax adjustments			2,414
Other comprehensive income (loss) before reclassifications	7,314	4,155	(18,716)
Other	(74)
Other comprehensive income (loss)	30,049	9,250	(5,383)
Ending balance	(54,878)	(84,927)	(94,177)
Operating expense [Member] \| Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		0	0
Operating expense [Member] \| Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		0	0
Operating expense [Member] \| Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		(1,143)	(1,200)
Operating expense [Member] \| Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		(1,143)	(1,200)
General and administrative expense [Member] \| Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		0	0
General and administrative expense [Member] \| Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		0	0
General and administrative expense [Member] \| Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		(386)	(413)
General and administrative expense [Member] \| Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI		(386)	(413)
Interest expense, net [Member] \| Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	0	0	0
Interest expense, net [Member] \| Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	5,499	6,624	8,331
Interest expense, net [Member] \| Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	0	0	0
Interest expense, net [Member] \| Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	5,499	$ 6,624	$ 8,331
Pension Plan [Member] \| Other Income [Member] \| Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	0
Pension Plan [Member] \| Other Income [Member] \| Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	0
Pension Plan [Member] \| Other Income [Member] \| Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	(814)
Pension Plan [Member] \| Other Income [Member] \| Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	(814)
Sale of U.K. and Amsterdam Operations [Member] \| Other Income [Member] \| Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	18,124
Sale of U.K. and Amsterdam Operations [Member] \| Other Income [Member] \| Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	0
Sale of U.K. and Amsterdam Operations [Member] \| Other Income [Member] \| Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	0
Sale of U.K. and Amsterdam Operations [Member] \| Other Income [Member] \| Total [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net loss (gain) reclassified from AOCI	$ 18,124

NET (LOSS) INCOME PER COMMON UNIT Narrative (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Series D preferred units outstanding	23,246,650	0

NET (LOSS) INCOME PER COMMON UNIT Table - Net (Loss) Income per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Series D Preferred Unit accretion (refer to Note 19)									$ (8,195)
Net income	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	205,794	$ 147,964	$ 150,003
Distributions to preferred limited partners									(92,540)	(40,448)	(1,925)
Distributions to general partner (including incentive distribution rights)									(1,141)	(54,921)	(51,284)
Distributions to common limited partners									(248,705)	(407,681)	(342,598)
Distribution equivalent rights to restricted units									(2,045)	(2,965)	(2,697)
Distributions in excess of earnings									(138,637)	(358,051)	(248,501)
Distributions to common limited partners									248,705	407,681	342,598
Allocation of distributions in excess of earnings									(138,659)	(350,890)	(243,530)
Loss to common unitholders attributable to the Merger (refer to Note 4)									(377,079)	0	0
Net (loss) income attributable to common units:									$ (275,228)	$ 56,791	$ 99,068
Basic weighted-average common units outstanding									99,490,495	88,825,964	78,080,484
Diluted common units outstanding:
Basic weighted-average common units outstanding									99,490,495	88,825,964	78,080,484
Effect of dilutive potential common units									40,677	0	32,518
Diluted weighted-average common units outstanding									99,531,172	88,825,964	78,113,002
Basic net (loss) income per common unit	$ (0.31)	$ (3.49)	$ 0.15	$ 1.15	$ 0.00	$ 0.15	$ 0.05	$ 0.49	$ (2.77)	$ 0.64	$ 1.27
Diluted net (loss) income per common unit	$ (0.31)	$ (3.49)	$ 0.15	$ 1.15	$ 0.00	$ 0.15	$ 0.05	$ 0.49	$ (2.77)	$ 0.64	$ 1.27
Common Limited Partner [Member]
Series D Preferred Unit accretion (refer to Note 19)									$ (8,195)	$ 0	$ 0
Net income									$ 110,788	$ 60,610	$ 102,580

STATEMENTS OF CASH FLOWS Table 1 - Changes in Current Assets and Current Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Decrease (increase) in current assets:
Accounts receivable	$ 22,482	$ (865)	$ (23,234)
Receivable from related parties	160	112	(317)
Inventories	3,819	11,936	940
Other current assets	3,694	3,393	8,128
Increase (decrease) in current liabilities:
Accounts payable	8,003	(30,409)	14,071
Payable to related party	0	0	894
Accrued interest payable	(4,279)	6,489	(256)
Accrued liabilities	39,577	(11,157)	161
Taxes other than income tax	4,521	(3,529)	2,690
Income tax payable	285	(2,463)	639
Changes in current assets and current liabilities	$ 78,262	$ (26,493)	$ 3,716

STATEMENTS OF CASH FLOWS Table 2 - Cash Flows Related to Interest and Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of amount capitalized	$ 183,078	$ 158,089	$ 142,663
Cash paid for income taxes, net of tax refunds received	$ 8,535	$ 11,338	$ 11,847

EMPLOYEE BENEFIT PLANS Narrative 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Thrift Plan, description	The NuStar Thrift Plan (the Thrift Plan) is a qualified defined contribution plan that became effective June 26, 2006. Participation in the Thrift Plan is voluntary and open to substantially all our domestic employees upon their dates of hire. Thrift Plan participants can contribute from 1% up to 30% of their total annual compensation to the Thrift Plan in the form of pre-tax and/or after tax employee contributions. We make matching contributions in an amount equal to 100% of each participant’s employee contributions up to a maximum of 6% of the participant’s total annual compensation.
Thrift Plan matching contributions	$ 7.4	$ 6.9	$ 6.6
Benefit plan costs, international employees	$ 2.5	2.5	$ 2.4
Pension Plan, description	The NuStar Pension Plan (the Pension Plan) is a qualified non-contributory defined benefit pension plan that provides eligible U.S. employees with retirement income as calculated under a cash balance formula. Under the cash balance formula, benefits are determined based on age, years of vesting service and interest credits, and employees become fully vested in their benefits upon attaining three years of vesting service. Prior to January 1, 2014, eligible employees were covered under either a cash balance formula or a final average pay formula (FAP). Effective January 1, 2014, the Pension Plan was amended to freeze the FAP benefits as of December 31, 2013, and going forward, all eligible employees are covered under the cash balance formula discussed above.
Defined benefit plan, assumptions used in calculations description	We amortize prior service costs and credits on a straight-line basis over the average remaining service period of employees expected to receive benefits under our Pension Plans and other postretirement benefit plans (“Amortization of prior service credit” in table above). We amortize the actuarial gains and losses that exceed 10% of the greater of the projected benefit obligation or market-related value of plan assets (smoothed asset value) over the average remaining service period of active employees expected to receive benefits under our Pension Plans and other postretirement benefit plans (“Amortization of net actuarial loss” in table above).
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for the Pension Plans	$ 139.7	$ 146.3

EMPLOYEE BENEFIT PLANS Table 1 - Changes in Benefit Obligation/Fair Value of Plan Assets/Funded Status/Amounts Recognized in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Change in benefit obligation:
Benefit obligation, January 1	$ 149,817	$ 127,402
Service cost	9,621	8,955	$ 7,703
Interest cost	4,824	4,507	4,023
Benefits paid	(7,929)	(5,941)
Participant contributions	0	0
Actuarial loss (gain)	(14,500)	14,894
Benefit obligation, December 31	141,833	149,817	127,402
Change in plan assets:
Plan assets at fair value, January 1	129,878	107,644
Actual return on plan assets	(6,034)	17,070
Employer contributions	11,034	11,105
Benefits paid	(7,929)	(5,941)
Participant contributions	0	0
Plan assets at fair value, December 31	126,949	129,878	107,644
Reconciliation of funded status:
Fair value of plan assets at December 31	129,878	107,644	107,644	$ 126,949	$ 129,878
Less: Benefit obligation at December 31	149,817	127,402	127,402	141,833	149,817
Funded status at December 31				(14,884)	(19,939)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities				(267)	(210)
Other long-term liabilities				(14,617)	(19,729)
Net pension liability				(14,884)	(19,939)
Other Postretirement Benefit Plans [Member]
Change in benefit obligation:
Benefit obligation, January 1	12,410	11,061
Service cost	504	456	419
Interest cost	429	430	401
Benefits paid	(255)	(342)
Participant contributions	87	215
Actuarial loss (gain)	(2,267)	590
Benefit obligation, December 31	10,908	12,410	11,061
Change in plan assets:
Plan assets at fair value, January 1	0	0
Actual return on plan assets	0	0
Employer contributions	168	127
Benefits paid	(255)	(342)
Participant contributions	87	215
Plan assets at fair value, December 31	0	0	0
Reconciliation of funded status:
Fair value of plan assets at December 31	0	0	0	0	0
Less: Benefit obligation at December 31	$ 12,410	$ 11,061	$ 11,061	10,908	12,410
Funded status at December 31				(10,908)	(12,410)
Amounts recognized in the consolidated balance sheets:
Accrued liabilities				(362)	(376)
Other long-term liabilities				(10,546)	(12,034)
Net pension liability				$ (10,908)	$ (12,410)

EMPLOYEE BENEFIT PLANS Table 2 - Components of Net Periodic Benefit Cost (Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9,621	$ 8,955	$ 7,703
Interest cost	4,824	4,507	4,023
Expected return on plan assets	(7,417)	(6,411)	(5,407)
Amortization of prior service credit	(2,057)	(2,059)	(2,063)
Amortization of net actuarial loss	2,174	1,484	1,091
Net periodic benefit cost (income)	7,145	6,476	5,347
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	504	456	419
Interest cost	429	430	401
Expected return on plan assets	0	0	0
Amortization of prior service credit	(1,145)	(1,145)	(1,145)
Amortization of net actuarial loss	214	191	181
Net periodic benefit cost (income)	$ 2	$ (68)	$ (144)

EMPLOYEE BENEFIT PLANS Table 3 - Adjustments to Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Income tax (expense) benefit	$ (94)	$ 184	$ 60
Total changes in other comprehensive income (loss)	2,334	(6,170)	(2,850)
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss) gain	1,049	(4,235)	(7,544)
Amortization of prior service credit	(2,057)	(2,059)	(2,063)
Amortization of net actuarial loss	2,174	1,484	1,091
Net (gain) loss reclassified into income	117	(575)	(972)
Reclassification of stranded tax effects	(74)	0	0
Income tax (expense) benefit	(69)	162	57
Total changes in other comprehensive income (loss)	1,023	(4,648)	(8,459)
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss) gain	2,267	(590)	(368)
Amortization of prior service credit	(1,145)	(1,145)	(1,145)
Amortization of net actuarial loss	214	191	181
Net (gain) loss reclassified into income	(931)	(954)	(964)
Reclassification of stranded tax effects	0	0	0
Income tax (expense) benefit	(25)	22	3
Total changes in other comprehensive income (loss)	$ 1,311	$ (1,522)	$ (1,329)

EMPLOYEE BENEFIT PLANS Table 4 - Amounts Recorded as a Component of Accumulated Other Comprehensive (Loss) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial loss	$ (27,955)	$ (31,178)
Prior service credit	14,547	16,604
Deferred tax asset (liability)	76	219
Accumulated other comprehensive income (loss), net of tax	(13,332)	(14,355)
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial loss	(1,673)	(4,154)
Prior service credit	8,319	9,464
Deferred tax asset (liability)	0	25
Accumulated other comprehensive income (loss), net of tax	$ 6,646	$ 5,335

EMPLOYEE BENEFIT PLANS Table 5 - Amounts Expected to be Recognized in Net Periodic Benefit Cost (Income) in Following Year (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss	$ 846
Prior service credit	(2,057)
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss	42
Prior service credit	$ (1,145)

EMPLOYEE BENEFIT PLANS Narrative 2 (Details)	Dec. 31, 2018
Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, target plan asset allocations	65.00%
Fixed income investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, target plan asset allocations	35.00%

EMPLOYEE BENEFIT PLANS Table 6 - Major Classes of Plan Assets Measured at Fair Value (Details) - Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 126,949	$ 129,878	$ 107,644
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	56,424	54,525
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70,525	75,353
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash equivalent securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	608	381
Cash equivalent securities [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	608	381
Cash equivalent securities [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash equivalent securities [Member] \| Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large cap equity fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70,525	75,353
U.S. large cap equity fund [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large cap equity fund [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70,525	75,353
U.S. large cap equity fund [Member] \| Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International stock index fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,391	14,480
International stock index fund [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,391	14,480
International stock index fund [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International stock index fund [Member] \| Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Bond market index fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42,425	39,664
Bond market index fund [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42,425	39,664
Bond market index fund [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Bond market index fund [Member] \| Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0

EMPLOYEE BENEFIT PLANS Narrative 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan contributions	$ 11,034	$ 11,105
Estimated future employer contributions in next fiscal year	11,300
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan contributions	168	$ 127
Estimated future employer contributions in next fiscal year	$ 300

EMPLOYEE BENEFIT PLANS Table 7 - Estimated Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Estimated Future Benefit Payments
2019	$ 9,454
2020	10,309
2021	11,072
2022	11,593
2023	12,274
Years 2024-2028	68,198
Other Postretirement Benefit Plans [Member]
Estimated Future Benefit Payments
2019	362
2020	390
2021	423
2022	475
2023	503
Years 2024-2028	$ 3,200

EMPLOYEE BENEFIT PLANS Table 8 - Assumptions - Benefit Obligations (Details)	Dec. 31, 2018	Dec. 31, 2017
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.40%	3.72%
Rate of compensation increase	3.51%	3.51%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.53%	3.82%

EMPLOYEE BENEFIT PLANS Table 9 - Assumptions - Net Periodic Benefit Cost (Income) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans (The Pension Plan, Excess Pension Plan and SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.72%	4.33%	4.61%
Expected long-term rate of return on plan assets	6.50%	6.00%	6.25%
Rate of compensation increase	3.51%	3.51%	3.51%
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.82%	4.49%	4.75%

EMPLOYEE BENEFIT PLANS Table 10 - Assumptions - Health Care Cost Trend Rates (Details) - Other Postretirement Benefit Plans [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	6.84%	6.84%
Rate to which the cost trend rate was assumed to decrease (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2028	2028
Effect of one percentage point increase, description	The cap on the increase in employer’s cost is 2.5% per year. The assumed increase in total health care cost exceeds the 2.5% indexed cap, so increasing or decreasing the health care cost trend rate by 1% does not materially change our obligation or expense for the postretirement health care plan.

UNIT-BASED COMPENSATION Narrative 1 (Details) - shares	Dec. 31, 2018	Jul. 20, 2018	Jun. 30, 2018	Mar. 01, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common unit conversion rate		55.00%
The 2000 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, number of units authorized				3,250,000
Unit-based compensation, number of units available to be awarded	655,848
The 2006 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, number of units available to be awarded	219,632
The 2006 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, number of units authorized			2,000,000

UNIT-BASED COMPENSATION Table 1 - Information for LTIP Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, outstanding (units)	1,277,480	902,911	793,097
Compensation expense	$ 13,162	$ 8,727	$ 8,294
Restricted units, domestic employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, outstanding (units)	1,028,484	736,746	647,340	0
Compensation expense	$ 8,233	$ 7,881	$ 5,980
Restricted units, non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, outstanding (units)	59,752	27,097	18,134	0
Compensation expense	$ 524	$ 251	$ 388
Restricted units, international employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, outstanding (units)	30,918	58,107	50,609	0
Compensation expense	$ 1,158	$ 595	$ 715
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, outstanding (units)	80,690	38,865	35,373
Compensation expense	$ 1,889	$ 0	$ 1,211
Performance units awarded and outstanding	158,326	80,961	77,014
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 1,358	$ 0	$ 0
Performance units awarded and outstanding	0	0	0

UNIT-BASED COMPENSATION Narrative 2 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash payments made in connection with DERs	$ 2,045	$ 2,965	$ 2,697
Restricted units, domestic employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, vesting period	5 years
Restricted units, non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, vesting period	3 years
Minimum [Member] \| Restricted units, international employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, vesting period	3 years
Maximum [Member] \| Restricted units, international employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, vesting period	5 years

UNIT-BASED COMPENSATION Table 2 - Restricted Unit Activity (Details) - $ / shares		12 Months Ended
	Mar. 01, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, beginning balance (units)		902,911	793,097
Unit-based awards, ending balance (units)		1,277,480	902,911	793,097
Restricted units, domestic employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, beginning balance (units)		736,746	647,340	0
Unit-based awards, transferred (units)	586,524
Unit based awards, converted (units)		53,447
Unit-based awards, granted (units)		518,282	307,009	246,070
Unit-based awards, vested (units)		(235,746)	(201,466)	(180,724)
Unit-based awards, forfeited (units)		(44,245)	(16,137)	(4,530)
Unit-based awards, ending balance (units)		1,028,484	736,746	647,340
Weighted-average grant date fair value, period start		$ 35.95	$ 39.72	$ 0.00
Weighted-average grant date fair value, transferred	$ 35.03
Weighted-average grant date fair value, converted		24.99
Weighted-average grant date fair value, granted		24.07	29.56	47.70
Weighted-average grant date fair value, vested		35.12	38.74	35.50
Weighted-average grant date fair value, forfeited		36.05	40.00	35.03
Weighted-average grant date fair value, period end		$ 29.47	$ 35.95	$ 39.72
Restricted units, non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, beginning balance (units)		27,097	18,134	0
Unit-based awards, transferred (units)	17,629
Unit based awards, converted (units)		18,915
Unit-based awards, granted (units)		34,303	17,110	8,730
Unit-based awards, vested (units)		(20,563)	(8,147)	(8,225)
Unit-based awards, forfeited (units)		0	0	0
Unit-based awards, ending balance (units)		59,752	27,097	18,134
Restricted units, international employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, beginning balance (units)		58,107	50,609	0
Unit-based awards, transferred (units)	49,121
Unit based awards, converted (units)		0
Unit-based awards, granted (units)		16,197	24,533	20,107
Unit-based awards, vested (units)		(41,406)	(16,440)	(14,812)
Unit-based awards, forfeited (units)		(1,980)	(595)	(3,807)
Unit-based awards, ending balance (units)		30,918	58,107	50,609

UNIT-BASED COMPENSATION Narrative 3 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted units that vested during the period	$ 7.5	$ 6.5	$ 9.0
Units issued to satisfy award vestings, net of tax (units)	189,399
Unrecognized compensation cost	$ 29.2
Compensation cost not yet recognized, period for recognition	3 years 9 months 18 days
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of restricted units that vested during the period		$ 2.9
Units issued to satisfy award vestings, net of tax (units)		33,438
Unit-based compensation, description of performance units	The performance measure is determined each year by the NuStar GP, LLC Compensation Committee for the following year. Achievement of the performance measure determines the rate at which the performance units convert into our common units, which ranges from zero to 200% for certain awards.
Unit-based compensation, terms of performance units	Performance units awarded vest in three annual increments (tranches), based upon our achievement of the performance measure set by the Compensation Committee during the one-year performance periods that end on December 31 of each applicable year.
Unit-based awards, granted (units)	80,690	38,865	0
Unit-based awards, vested (units)	0	(53,063)	0
Unit-based awards, forfeited (units)	(38,865)		0

UNIT-BASED COMPENSATION Table 3 - Summary of Performance Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based awards, beginning balance (units)	902,911	793,097
Unit-based awards, ending balance (units)	1,277,480	902,911	793,097
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance units awarded and outstanding, period start	80,961	77,014
Performance units awarded	116,230	39,320
Additional performance units awarded		17,690
Unit-based awards, vested (units)	0	(53,063)	0
Unit-based awards, forfeited (units)	(38,865)		0
Performance units awarded and outstanding, period end	158,326	80,961	77,014
Unit-based awards, beginning balance (units)	38,865	35,373
Unit-based awards, granted (units)	80,690	38,865	0
Additional unit-based awards, granted (units)		17,690
Unit-based awards, ending balance (units)	80,690	38,865	35,373
Weighted-average grant date fair value, period start	$ 50.04	$ 31.75
Weighted-average grant date fair value, granted	23.43	50.04
Weighted-average grant date fair value of additional units, granted		31.75
Weighted-average grant date fair value, vested	0.00	31.75
Weighted-average grant date fair value, forfeited	50.04
Weighted-average grant date fair value, period end	$ 23.43	$ 50.04	$ 31.75

UNIT-BASED COMPENSATION Narrative 4 (Details) - $ / shares			12 Months Ended
	Jun. 29, 2018	Apr. 18, 2017	Dec. 31, 2018	Dec. 31, 2016
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation, description of unit awards			Unit awards are equity-classified awards of fully vested common units. We record compensation expense based on the fair value of the common units at the grant date.
Unit-based awards, granted (units)			55,133
Weighted-average grant date fair value, granted			$ 24.63
Common Limited Partner [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of units (units)	413,736	14,375,000		595,050
Common Limited Partner [Member] \| Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of units (units)			35,745

INCOME TAXES Table 1 - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
U.S.	$ 4,515	$ 3,117	$ 2,280
Foreign	4,658	6,335	6,329
Foreign withholding tax	192	479	3,833
Total current	9,365	9,931	12,442
Deferred:
U.S.	1,403	1,468	2,680
Foreign	394	(1,065)	(1,122)
Foreign withholding tax	246	(397)	(2,027)
Total deferred	2,043	6	(469)
Total income tax expense	$ 11,408	$ 9,937	$ 11,973

INCOME TAXES Narrative 1 (Details)	12 Months Ended
INCOME TAXES Narrative 1 (Details)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate reconciliation percent	21.00%	35.00%	35.00%

INCOME TAXES Table 2 - Tax Effects of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets:
Net operating losses	$ 21,009	$ 20,688
Employee benefits	362	483
Environmental and legal reserves	239	185
Allowance for bad debt	1,970	1,982
Other	1,796	2,050
Total deferred income tax assets	25,376	25,388
Less: Valuation allowance	(12,442)	(11,251)
Net deferred income tax assets	12,934	14,137
Deferred income tax liabilities:
Property, plant and equipment	(25,128)	(36,176)
Foreign withholding tax	(234)	0
Total deferred income tax liabilities	(25,362)	(36,176)
Net deferred income tax liability	(12,428)	(22,039)
Reported on the Consolidated Balance Sheets as:
Deferred income tax asset	0	233
Deferred income tax liability	(12,428)	(22,272)
Net deferred income tax liability	$ (12,428)	$ (22,039)

INCOME TAXES Narrative 2 - Operating Loss Carryforwards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective income tax rate reconciliation percent	21.00%	35.00%	35.00%
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 12,442,000	$ 11,251,000
Tax Cuts and Jobs Act, tax expense (benefit) impact		800,000
Tax Cuts and Jobs Act, mandatory tax on previously deferred earnings	(300,000)	700,000
Tax Cuts and Jobs Act, change in deferred tax assets valuation allowance		$ 100,000
Income tax effect of Global Intangible Low-Tax Income tax rules	100,000
Base Erosion Anti-Abuse Tax (BEAT) adjustment	0
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	9,300,000
Change in valuation allowance	$ 200,000
Foreign [Member] \| Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration date	Jan. 01, 2019
Foreign [Member] \| Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2028
U.S. [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 86,800,000
Change in valuation allowance	$ 900,000
U.S. [Member] \| Minimum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration date	Jan. 01, 2025
U.S. [Member] \| Maximum [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration date	Dec. 31, 2037

SEGMENT INFORMATION Table 1 - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	$ 1,961,757	$ 1,814,019	$ 1,756,682
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization expense									297,874	264,232	216,736
Operating income (loss):
Less general and administrative expenses									106,200	112,240	98,817
Less other depreciation and amortization expense									297,874	264,232	216,736
Total operating income (loss)	$ 89,968	$ 95,277	$ 79,838	$ 98,480	$ 74,018	$ 91,717	$ 73,404	$ 97,139	363,563	336,278	359,109
Pipeline Segment
Revenues:
Revenues									611,065	516,288	485,650
Pipeline Segment \| Third Party Revenue [Member]
Revenues:
Revenues									611,065	516,288	485,650
Storage Segment
Revenues:
Revenues									605,950	616,953	610,042
Storage Segment \| Third Party Revenue [Member]
Revenues:
Revenues									598,380	604,847	589,098
Storage Segment \| Intersegment revenue [Member]
Revenues:
Revenues									7,570	12,106	20,944
Fuels Marketing Segment \| Third Party Revenue [Member]
Revenues:
Revenues									752,312	692,884	681,934
Operating Segments [Member]
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization expense									288,999	255,534	208,217
Operating income (loss):
Less other depreciation and amortization expense									288,999	255,534	208,217
Total operating income (loss)									478,638	457,216	466,445
Operating Segments [Member] \| Pipeline Segment
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization expense									153,943	128,061	89,554
Operating income (loss):
Less other depreciation and amortization expense									153,943	128,061	89,554
Total operating income (loss)									272,695	231,795	248,238
Operating Segments [Member] \| Storage Segment
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization expense									135,056	127,473	118,663
Operating income (loss):
Less other depreciation and amortization expense									135,056	127,473	118,663
Total operating income (loss)									181,471	219,439	214,801
Operating Segments [Member] \| Fuels Marketing Segment
Operating income (loss):
Total operating income (loss)									24,440	5,983	3,406
Intersegment Eliminations [Member]
Revenues:
Revenues									(7,570)	(12,106)	(20,944)
Operating income (loss):
Total operating income (loss)									32	(1)	0
Corporate, Non-Segment [Member]
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization expense									8,875	8,698	8,519
Operating income (loss):
Less general and administrative expenses									106,200	112,240	98,817
Less other depreciation and amortization expense									$ 8,875	$ 8,698	$ 8,519

SEGMENT INFORMATION Table 2 - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues By Geographic Areas
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	$ 1,961,757	$ 1,814,019	$ 1,756,682
United States
Revenues By Geographic Areas
Revenues									1,481,863	1,406,626	1,352,936
Netherlands
Revenues By Geographic Areas
Revenues									398,382	322,251	313,395
Other
Revenues By Geographic Areas
Revenues									$ 81,512	$ 85,142	$ 90,351

SEGMENT INFORMATION Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Major Customer [Line Items]
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	$ 1,961,757	$ 1,814,019	$ 1,756,682
Sales Revenue, Net [Member]
Revenue, Major Customer [Line Items]
Consolidated revenues, percent									10.00%
Sales Revenue, Net [Member] \| Valero Energy Corporation [Member]
Revenue, Major Customer [Line Items]
Largest customer percentage of revenue									16.00%	17.00%	18.00%
Revenues									$ 309,800	$ 300,000	$ 310,000

SEGMENT INFORMATION Table 3 - Property, Plant, and Equipment, Net, by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Long-Lived Assets By Geographic Areas
Long-lived assets	$ 4,288,622	$ 4,300,933
United States
Long-Lived Assets By Geographic Areas
Long-lived assets	3,687,910	3,519,965
Netherlands
Long-Lived Assets By Geographic Areas
Long-lived assets	514,541	572,817
Other
Long-Lived Assets By Geographic Areas
Long-lived assets	$ 86,171	$ 208,151

SEGMENT INFORMATION Table 4 - Assets by Reportable Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Segment Information
Total consolidated assets	$ 6,349,140	$ 6,535,233
Operating Segments [Member]
Segment Information
Total consolidated assets	6,174,474	6,346,726
Operating Segments [Member] \| Pipeline Segment
Segment Information
Total consolidated assets	3,637,226	3,492,417
Operating Segments [Member] \| Storage Segment
Segment Information
Total consolidated assets	2,424,342	2,735,563
Operating Segments [Member] \| Fuels Marketing Segment
Segment Information
Total consolidated assets	112,906	118,746
Operating Segments [Member] \| Other partnership assets
Segment Information
Total consolidated assets	$ 174,666	$ 188,507

SEGMENT INFORMATION Table 5 - Capital Expenditures by Reportable Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Information
Capital expenditures	$ 494,954	$ 1,846,357	$ 300,015
Pipeline Segment
Segment Information
Capital expenditures	288,035	1,596,311	88,373
Storage Segment
Segment Information
Capital expenditures	202,782	244,398	206,641
Other partnership assets
Segment Information
Capital expenditures	$ 4,137	$ 5,648	$ 5,001

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS Narrative (Details)	12 Months Ended
	Dec. 31, 2018
NuStar Logistics
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest	100.00%
NuPOP
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest	100.00%

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS Table 1 - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 13,644	$ 24,292	$ 35,942	$ 118,862
Receivables, net	148,308	176,775
Inventories	22,713	26,857
Prepaid and other current assets	17,493	22,508
Intercompany receivable	0	0
Total current assets	202,158	250,432
Property, plant and equipment, net	4,288,622	4,300,933
Intangible assets, net	733,056	784,479
Goodwill	1,036,976	1,097,475	696,637
Investment in wholly owned subsidiaries	0	0
Deferred income tax asset	0	233
Other long-term assets, net	88,328	101,681
Total assets	6,349,140	6,535,233
Liabilities, Mezzanine Equity and Partners' Equity
Accounts payable	143,121	145,932
Short-term debt	18,500	35,000
Current portion of long-term debt	0	349,990
Accrued interest payable	36,293	40,449
Accrued liabilities	101,993	61,578
Taxes other than income tax	19,083	14,385
Income tax payable	4,445	4,172
Intercompany payable	0	0
Total current liabilities	323,435	651,506
Long-term debt, less current portion	3,111,996	3,263,069
Deferred income tax liability	12,428	22,272
Other long-term liabilities	79,558	118,297
Series D preferred units	563,992	0	0	0
Total partners' equity	2,257,731	2,480,089	1,611,617	1,609,844
Total liabilities, mezzanine equity and partners’ equity	6,349,140	6,535,233
Eliminations
Assets
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Inventories	0	0
Prepaid and other current assets	0	0
Intercompany receivable	(1,828,416)	(3,112,164)
Total current assets	(1,828,416)	(3,112,164)
Property, plant and equipment, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Investment in wholly owned subsidiaries	(7,388,660)	(5,008,132)
Deferred income tax asset		0
Other long-term assets, net	0	0
Total assets	(9,217,076)	(8,120,296)
Liabilities, Mezzanine Equity and Partners' Equity
Accounts payable	0	0
Short-term debt	0	0
Current portion of long-term debt		0
Accrued interest payable	0	0
Accrued liabilities	0	0
Taxes other than income tax	0	0
Income tax payable	0	0
Intercompany payable	(1,828,416)	(3,112,164)
Total current liabilities	(1,828,416)	(3,112,164)
Long-term debt, less current portion	0	0
Deferred income tax liability	0	0
Other long-term liabilities	0	0
Series D preferred units	0
Total partners' equity	(7,388,660)	(5,008,132)
Total liabilities, mezzanine equity and partners’ equity	(9,217,076)	(8,120,296)
Parent Company Guarantor [Member] \| NuStar Energy \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	1,255	885	870	885
Receivables, net	0	0
Inventories	0	0
Prepaid and other current assets	61	61
Intercompany receivable	0	0
Total current assets	1,316	946
Property, plant and equipment, net	0	0
Intangible assets, net	0	0
Goodwill	0	0
Investment in wholly owned subsidiaries	3,355,636	2,891,371
Deferred income tax asset		0
Other long-term assets, net	304	303
Total assets	3,357,256	2,892,620
Liabilities, Mezzanine Equity and Partners' Equity
Accounts payable	6,460	4,078
Short-term debt	0	0
Current portion of long-term debt		0
Accrued interest payable	0	0
Accrued liabilities	1,280	1,105
Taxes other than income tax	125	125
Income tax payable	0	0
Intercompany payable	472,790	322,296
Total current liabilities	480,655	327,604
Long-term debt, less current portion	0	0
Deferred income tax liability	0	0
Other long-term liabilities	0	0
Series D preferred units	563,992
Total partners' equity	2,312,609	2,565,016
Total liabilities, mezzanine equity and partners’ equity	3,357,256	2,892,620
Subsidiary Issuer [Member] \| NuStar Logistics \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	51	29	5	4
Receivables, net	2,212	280
Inventories	1,741	1,686
Prepaid and other current assets	14,422	11,412
Intercompany receivable	1,327,833	3,112,164
Total current assets	1,346,259	3,125,571
Property, plant and equipment, net	1,858,264	1,893,720
Intangible assets, net	49,107	58,530
Goodwill	149,453	149,453
Investment in wholly owned subsidiaries	1,750,256	24,162
Deferred income tax asset		0
Other long-term assets, net	54,429	65,684
Total assets	5,207,768	5,317,120
Liabilities, Mezzanine Equity and Partners' Equity
Accounts payable	39,680	27,642
Short-term debt	18,500	35,000
Current portion of long-term debt		349,990
Accrued interest payable	36,253	40,402
Accrued liabilities	24,858	17,628
Taxes other than income tax	7,285	7,110
Income tax payable	457	732
Intercompany payable	0	0
Total current liabilities	127,033	478,504
Long-term debt, less current portion	3,050,531	3,201,220
Deferred income tax liability	1,675	1,262
Other long-term liabilities	28,392	58,806
Series D preferred units	0
Total partners' equity	2,000,137	1,577,328
Total liabilities, mezzanine equity and partners’ equity	5,207,768	5,317,120
Guarantor Subsidiaries [Member] \| NuPOP \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Inventories	5,237	8,611
Prepaid and other current assets	908	4,191
Intercompany receivable	0	0
Total current assets	6,145	12,802
Property, plant and equipment, net	615,549	591,070
Intangible assets, net	0	0
Goodwill	170,652	170,652
Investment in wholly owned subsidiaries	1,425,283	1,301,717
Deferred income tax asset		0
Other long-term assets, net	26,716	27,493
Total assets	2,244,345	2,103,734
Liabilities, Mezzanine Equity and Partners' Equity
Accounts payable	6,331	13,160
Short-term debt	0	0
Current portion of long-term debt		0
Accrued interest payable	0	0
Accrued liabilities	8,082	9,450
Taxes other than income tax	4,718	3,794
Income tax payable	2	4
Intercompany payable	1,355,626	1,277,691
Total current liabilities	1,374,759	1,304,099
Long-term debt, less current portion	0	0
Deferred income tax liability	9	12
Other long-term liabilities	12,348	8,861
Series D preferred units	0
Total partners' equity	857,229	790,762
Total liabilities, mezzanine equity and partners’ equity	2,244,345	2,103,734
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	12,338	23,378	$ 35,067	$ 117,973
Receivables, net	146,096	176,495
Inventories	15,735	16,560
Prepaid and other current assets	2,102	6,844
Intercompany receivable	500,583	0
Total current assets	676,854	223,277
Property, plant and equipment, net	1,814,809	1,816,143
Intangible assets, net	683,949	725,949
Goodwill	716,871	777,370
Investment in wholly owned subsidiaries	857,485	790,882
Deferred income tax asset		233
Other long-term assets, net	6,879	8,201
Total assets	4,756,847	4,342,055
Liabilities, Mezzanine Equity and Partners' Equity
Accounts payable	90,650	101,052
Short-term debt	0	0
Current portion of long-term debt		0
Accrued interest payable	40	47
Accrued liabilities	67,773	33,395
Taxes other than income tax	6,955	3,356
Income tax payable	3,986	3,436
Intercompany payable	0	1,512,177
Total current liabilities	169,404	1,653,463
Long-term debt, less current portion	61,465	61,849
Deferred income tax liability	10,744	20,998
Other long-term liabilities	38,818	50,630
Series D preferred units	0
Total partners' equity	4,476,416	2,555,115
Total liabilities, mezzanine equity and partners’ equity	$ 4,756,847	$ 4,342,055

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS Table 2 - Condensed Consolidating Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	$ 1,961,757	$ 1,814,019	$ 1,756,682
Costs and expenses									1,598,194	1,477,741	1,397,573
Operating income (loss)	89,968	95,277	79,838	98,480	74,018	91,717	73,404	97,139	363,563	336,278	359,109
Equity in earnings (loss) of subsidiaries									0	0	0
Interest income (expense), net									(186,237)	(173,083)	(138,350)
Other income (expense), net									39,876	(5,294)	(58,783)
Income before income tax expense									217,202	157,901	161,976
Income tax (benefit) expense									11,408	9,937	11,973
Net income (loss)	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	205,794	147,964	150,003
Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenues									(705)	(1,018)	(1,738)
Costs and expenses									(705)	(1,018)	(1,738)
Operating income (loss)									0	0	0
Equity in earnings (loss) of subsidiaries									(559,302)	(387,264)	(376,263)
Interest income (expense), net									0	0	0
Other income (expense), net									0	0	0
Income before income tax expense									(559,302)	(387,264)	(376,263)
Income tax (benefit) expense									0	0	0
Net income (loss)									(559,302)	(387,264)	(376,263)
Parent Company Guarantor [Member] \| NuStar Energy \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									0	0	0
Costs and expenses									2,407	1,868	1,806
Operating income (loss)									(2,407)	(1,868)	(1,806)
Equity in earnings (loss) of subsidiaries									207,973	149,775	151,794
Interest income (expense), net									228	57	0
Other income (expense), net									0	0	18
Income before income tax expense									205,794	147,964	150,006
Income tax (benefit) expense									0	0	3
Net income (loss)									205,794	147,964	150,003
Subsidiary Issuer [Member] \| NuStar Logistics \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									485,603	496,454	511,650
Costs and expenses									317,286	317,871	302,099
Operating income (loss)									168,317	178,583	209,551
Equity in earnings (loss) of subsidiaries									17,167	(10,616)	(13,769)
Interest income (expense), net									(191,835)	(176,897)	(139,827)
Other income (expense), net									3,876	145	(58,264)
Income before income tax expense									(2,475)	(8,785)	(2,309)
Income tax (benefit) expense									588	(820)	1,607
Net income (loss)									(3,063)	(7,965)	(3,916)
Guarantor Subsidiaries [Member] \| NuPOP \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									260,679	221,125	224,966
Costs and expenses									163,667	146,243	150,384
Operating income (loss)									97,012	74,882	74,582
Equity in earnings (loss) of subsidiaries									121,913	89,405	82,202
Interest income (expense), net									(7,127)	(5,587)	(744)
Other income (expense), net									446	3	(26)
Income before income tax expense									212,244	158,703	156,014
Income tax (benefit) expense									(3)	2	(23)
Net income (loss)									212,247	158,701	156,037
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues									1,216,180	1,097,458	1,021,804
Costs and expenses									1,115,539	1,012,777	945,022
Operating income (loss)									100,641	84,681	76,782
Equity in earnings (loss) of subsidiaries									212,249	158,700	156,036
Interest income (expense), net									12,497	9,344	2,221
Other income (expense), net									35,554	(5,442)	(511)
Income before income tax expense									360,941	247,283	234,528
Income tax (benefit) expense									10,823	10,755	10,386
Net income (loss)									$ 350,118	$ 236,528	$ 224,142

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS Table 3 - Condensed Consolidating Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	$ 205,794	$ 147,964	$ 150,003
Other comprehensive income (loss):
Foreign currency translation adjustment									4,304	17,466	(8,243)
Net loss on pension and other postretirement benefit adjustments, net of tax benefit									2,334	(6,170)	(2,850)
Net gain (loss) on cash flow hedges									23,411	(2,046)	5,710
Total other comprehensive income (loss)									30,049	9,250	(5,383)
Comprehensive income (loss)									235,843	157,214	144,620
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									(559,302)	(387,264)	(376,263)
Other comprehensive income (loss):
Foreign currency translation adjustment									0	0	0
Net loss on pension and other postretirement benefit adjustments, net of tax benefit									0	0	0
Net gain (loss) on cash flow hedges									0	0	0
Total other comprehensive income (loss)									0	0	0
Comprehensive income (loss)									(559,302)	(387,264)	(376,263)
Parent Company Guarantor [Member] \| NuStar Energy \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									205,794	147,964	150,003
Other comprehensive income (loss):
Foreign currency translation adjustment									0	0	0
Net loss on pension and other postretirement benefit adjustments, net of tax benefit									0	0	0
Net gain (loss) on cash flow hedges									0	0	0
Total other comprehensive income (loss)									0	0	0
Comprehensive income (loss)									205,794	147,964	150,003
Subsidiary Issuer [Member] \| NuStar Logistics \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									(3,063)	(7,965)	(3,916)
Other comprehensive income (loss):
Foreign currency translation adjustment									0	0	0
Net loss on pension and other postretirement benefit adjustments, net of tax benefit									0	0	0
Net gain (loss) on cash flow hedges									23,411	(2,046)	5,710
Total other comprehensive income (loss)									23,411	(2,046)	5,710
Comprehensive income (loss)									20,348	(10,011)	1,794
Guarantor Subsidiaries [Member] \| NuPOP \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									212,247	158,701	156,037
Other comprehensive income (loss):
Foreign currency translation adjustment									0	0	0
Net loss on pension and other postretirement benefit adjustments, net of tax benefit									0	0	0
Net gain (loss) on cash flow hedges									0	0	0
Total other comprehensive income (loss)									0	0	0
Comprehensive income (loss)									212,247	158,701	156,037
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									350,118	236,528	224,142
Other comprehensive income (loss):
Foreign currency translation adjustment									4,304	17,466	(8,243)
Net loss on pension and other postretirement benefit adjustments, net of tax benefit									2,334	(6,170)	(2,850)
Net gain (loss) on cash flow hedges									0	0	0
Total other comprehensive income (loss)									6,638	11,296	(11,093)
Comprehensive income (loss)									$ 356,756	$ 247,824	$ 213,049

CONDENSED CONSOLIDATING FINANCIAL STATEMENTS Table 4 - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net cash provided by (used in) operating activities	$ 544,207	$ 406,799	$ 436,761
Cash flows from investing activities:
Capital expenditures	(457,452)	(384,638)	(204,358)
Change in accounts payable related to capital expenditures	(7,683)	36,903	(11,063)
Acquisitions	(37,502)	(1,461,719)	(95,657)
Proceeds from Axeon term loan	0	110,000	0
Proceeds from insurance recoveries	78,419	977	0
Proceeds from sale of European operations	266,740	0	0
Proceeds from sale or disposition of assets	3,700	2,036	0
Investment in subsidiaries	0	0	0
Net cash used in investing activities	(153,778)	(1,696,441)	(311,078)
Cash flows from financing activities:
Debt borrowings	1,872,653	3,060,100	1,406,729
Debt repayments	(2,381,776)	(2,487,539)	(1,456,152)
Proceeds from issuance of Series D preferred units	590,000	0	0
Payment of issuance costs for Series D preferred units	(34,203)	0	0
Proceeds from issuance of other preferred units, net of issuance costs	0	538,560	218,400
Proceeds from issuance of common units, net of issuance costs	10,000	643,878	27,710
Contributions from general partner	204	13,737	680
Distributions to preferred unitholders	(90,670)	(38,833)	0
Distributions to common unitholders and general partner	(300,777)	(446,306)	(392,962)
Cash consideration for Merger (Note 4)	(67,795)	0	0
Proceeds from termination of interest rate swaps	8,048	0	0
Contributions from (distributions to) affiliates	0	0	0
Net intercompany activity	0	0	0
Other, net	(5,551)	(7,325)	(15,729)
Net cash provided by (used in) financing activities	(399,867)	1,276,272	(211,324)
Effect of foreign exchange rate changes on cash	(1,210)	1,720	2,721
Net (decrease) increase in cash and cash equivalents	(10,648)	(11,650)	(82,920)
Cash and cash equivalents as of the beginning of the period	24,292	35,942	118,862
Cash and cash equivalents as of the end of the period	13,644	24,292	35,942
Eliminations
Cash flows from operating activities:
Net cash provided by (used in) operating activities	(694,859)	(737,138)	(694,011)
Cash flows from investing activities:
Capital expenditures	0	0	0
Change in accounts payable related to capital expenditures	0	0	0
Acquisitions	0	0	0
Proceeds from Axeon term loan		0
Proceeds from insurance recoveries	0	0
Proceeds from sale of European operations	0
Proceeds from sale or disposition of assets	0	0
Investment in subsidiaries	2,529,840	1,262,126	212,900
Net cash used in investing activities	2,529,840	1,262,126	212,900
Cash flows from financing activities:
Debt borrowings	0	0	0
Debt repayments	0	0	0
Proceeds from issuance of Series D preferred units	0
Payment of issuance costs for Series D preferred units	0
Proceeds from issuance of other preferred units, net of issuance costs		0	0
Proceeds from issuance of common units, net of issuance costs	0	0	0
Contributions from general partner	0	0	0
Distributions to preferred unitholders	136,007	58,251
Distributions to common unitholders and general partner	451,184	669,482	589,463
Cash consideration for Merger (Note 4)	0
Proceeds from termination of interest rate swaps	0
Contributions from (distributions to) affiliates	(2,422,172)	(1,252,721)	(108,352)
Net intercompany activity	0	0	0
Other, net	0	0	0
Net cash provided by (used in) financing activities	(1,834,981)	(524,988)	481,111
Effect of foreign exchange rate changes on cash	0	0	0
Net (decrease) increase in cash and cash equivalents	0	0	0
Cash and cash equivalents as of the beginning of the period	0	0	0
Cash and cash equivalents as of the end of the period	0	0	0
Parent Company Guarantor [Member] \| NuStar Energy \| Reportable Legal Entities [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	444,233	483,481	391,773
Cash flows from investing activities:
Capital expenditures	0	0	0
Change in accounts payable related to capital expenditures	0	0	0
Acquisitions	0	0	0
Proceeds from Axeon term loan		0
Proceeds from insurance recoveries	0	0
Proceeds from sale of European operations	0
Proceeds from sale or disposition of assets	0	0
Investment in subsidiaries	(708,600)	(1,262,000)	0
Net cash used in investing activities	(708,600)	(1,262,000)	0
Cash flows from financing activities:
Debt borrowings	0	0	0
Debt repayments	0	0	0
Proceeds from issuance of Series D preferred units	590,000
Payment of issuance costs for Series D preferred units	(34,203)
Proceeds from issuance of other preferred units, net of issuance costs		538,560	218,400
Proceeds from issuance of common units, net of issuance costs	10,000	643,878	27,710
Contributions from general partner	204	13,737	680
Distributions to preferred unitholders	(90,670)	(38,833)
Distributions to common unitholders and general partner	(300,777)	(446,306)	(392,962)
Cash consideration for Merger (Note 4)	(67,936)
Proceeds from termination of interest rate swaps	0
Contributions from (distributions to) affiliates	0	0	0
Net intercompany activity	162,498	73,206	(241,131)
Other, net	(4,379)	(5,708)	(4,485)
Net cash provided by (used in) financing activities	264,737	778,534	(391,788)
Effect of foreign exchange rate changes on cash	0	0	0
Net (decrease) increase in cash and cash equivalents	370	15	(15)
Cash and cash equivalents as of the beginning of the period	885	870	885
Cash and cash equivalents as of the end of the period	1,255	885	870
Subsidiary Issuer [Member] \| NuStar Logistics \| Reportable Legal Entities [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	100,385	152,101	167,900
Cash flows from investing activities:
Capital expenditures	(71,044)	(47,600)	(64,334)
Change in accounts payable related to capital expenditures	11,101	(1,988)	(10,076)
Acquisitions	0	0	(95,657)
Proceeds from Axeon term loan		110,000
Proceeds from insurance recoveries	0	0
Proceeds from sale of European operations	0
Proceeds from sale or disposition of assets	2,674	1,955
Investment in subsidiaries	(1,711,975)	0	0
Net cash used in investing activities	(1,769,244)	62,367	(170,067)
Cash flows from financing activities:
Debt borrowings	1,840,853	2,969,400	1,365,529
Debt repayments	(2,349,476)	(2,400,739)	(1,419,852)
Proceeds from issuance of Series D preferred units	0
Payment of issuance costs for Series D preferred units	0
Proceeds from issuance of other preferred units, net of issuance costs		0	0
Proceeds from issuance of common units, net of issuance costs	0	0	0
Contributions from general partner	0	0	0
Distributions to preferred unitholders	(45,336)	(19,417)
Distributions to common unitholders and general partner	(150,388)	(223,153)	(196,481)
Cash consideration for Merger (Note 4)	0
Proceeds from termination of interest rate swaps	8,048
Contributions from (distributions to) affiliates	599,400	1,262,000	0
Net intercompany activity	1,766,881	(1,801,218)	255,326
Other, net	(1,101)	(1,317)	(2,354)
Net cash provided by (used in) financing activities	1,668,881	(214,444)	2,168
Effect of foreign exchange rate changes on cash	0	0	0
Net (decrease) increase in cash and cash equivalents	22	24	1
Cash and cash equivalents as of the beginning of the period	29	5	4
Cash and cash equivalents as of the end of the period	51	29	5
Guarantor Subsidiaries [Member] \| NuPOP \| Reportable Legal Entities [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	179,512	102,405	211,816
Cash flows from investing activities:
Capital expenditures	(19,152)	(35,041)	(52,637)
Change in accounts payable related to capital expenditures	(5,161)	5,964	(285)
Acquisitions	(37,502)	0	0
Proceeds from Axeon term loan		0
Proceeds from insurance recoveries	0	0
Proceeds from sale of European operations	0
Proceeds from sale or disposition of assets	31	18
Investment in subsidiaries	(54,600)	0	(212,900)
Net cash used in investing activities	(116,384)	(29,059)	(265,822)
Cash flows from financing activities:
Debt borrowings	0	0	0
Debt repayments	0	0	0
Proceeds from issuance of Series D preferred units	0
Payment of issuance costs for Series D preferred units	0
Proceeds from issuance of other preferred units, net of issuance costs		0	0
Proceeds from issuance of common units, net of issuance costs	0	0	0
Contributions from general partner	0	0	0
Distributions to preferred unitholders	(45,336)	(19,416)
Distributions to common unitholders and general partner	(150,388)	(223,153)	(196,481)
Cash consideration for Merger (Note 4)	0
Proceeds from termination of interest rate swaps	0
Contributions from (distributions to) affiliates	54,600	0	0
Net intercompany activity	77,996	169,223	250,487
Other, net	0	0	0
Net cash provided by (used in) financing activities	(63,128)	(73,346)	54,006
Effect of foreign exchange rate changes on cash	0	0	0
Net (decrease) increase in cash and cash equivalents	0	0	0
Cash and cash equivalents as of the beginning of the period	0	0	0
Cash and cash equivalents as of the end of the period	0	0	0
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	514,936	405,950	359,283
Cash flows from investing activities:
Capital expenditures	(367,256)	(301,997)	(87,387)
Change in accounts payable related to capital expenditures	(13,623)	32,927	(702)
Acquisitions	0	(1,461,719)	0
Proceeds from Axeon term loan		0
Proceeds from insurance recoveries	78,419	977
Proceeds from sale of European operations	266,740
Proceeds from sale or disposition of assets	995	63
Investment in subsidiaries	(54,665)	(126)	0
Net cash used in investing activities	(89,390)	(1,729,875)	(88,089)
Cash flows from financing activities:
Debt borrowings	31,800	90,700	41,200
Debt repayments	(32,300)	(86,800)	(36,300)
Proceeds from issuance of Series D preferred units	0
Payment of issuance costs for Series D preferred units	0
Proceeds from issuance of other preferred units, net of issuance costs		0	0
Proceeds from issuance of common units, net of issuance costs	0	0	0
Contributions from general partner	0	0	0
Distributions to preferred unitholders	(45,335)	(19,418)
Distributions to common unitholders and general partner	(150,408)	(223,176)	(196,501)
Cash consideration for Merger (Note 4)	141
Proceeds from termination of interest rate swaps	0
Contributions from (distributions to) affiliates	1,768,172	(9,279)	108,352
Net intercompany activity	(2,007,375)	1,558,789	(264,682)
Other, net	(71)	(300)	(8,890)
Net cash provided by (used in) financing activities	(435,376)	1,310,516	(356,821)
Effect of foreign exchange rate changes on cash	(1,210)	1,720	2,721
Net (decrease) increase in cash and cash equivalents	(11,040)	(11,689)	(82,906)
Cash and cash equivalents as of the beginning of the period	23,378	35,067	117,973
Cash and cash equivalents as of the end of the period	$ 12,338	$ 23,378	$ 35,067

Table - Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Revenues	$ 509,309	$ 490,363	$ 486,204	$ 475,881	$ 450,535	$ 440,566	$ 435,488	$ 487,430	$ 1,961,757	$ 1,814,019	$ 1,756,682
Operating income (loss)	89,968	95,277	79,838	98,480	74,018	91,717	73,404	97,139	363,563	336,278	359,109
Net income (loss)	$ 2,126	$ 48,136	$ 29,399	$ 126,133	$ 25,182	$ 38,592	$ 26,250	$ 57,940	$ 205,794	$ 147,964	$ 150,003
Basic net (loss) income per common unit	$ (0.31)	$ (3.49)	$ 0.15	$ 1.15	$ 0.00	$ 0.15	$ 0.05	$ 0.49	$ (2.77)	$ 0.64	$ 1.27
Diluted net (loss) income per common unit	(0.31)	(3.49)	0.15	1.15	0.00	0.15	0.05	0.49	(2.77)	0.64	1.27
Common Limited Partner [Member]
Distribution Made to Limited Partner [Line Items]
Cash distributions per unit applicable to limited partners	$ 0.60	$ 0.60	$ 0.60	$ 0.60	$ 1.095	$ 1.095	$ 1.095	$ 1.095	$ 2.40	$ 4.380	$ 4.380
Quarterly Financial Data [Abstract]
Net income (loss)									$ 110,788	$ 60,610	$ 102,580

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

QUARTERLY FINANCIAL DATA (UNAUDITED) Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gain (loss) related to hurricane activity	$ 78,756	$ (5,000)	$ 0
Non-cash loss on sale of assets	(43,366)	0	0
Loss to common unitholders attributable to the Merger	(377,079)	0	$ 0
Other Nonoperating Income (Expense) [Member]
Gain (loss) related to hurricane activity	78,800	$ (5,000)
Sale of U.K. and Amsterdam Operations [Member] \| Other Nonoperating Income (Expense) [Member]
Non-cash loss on sale of assets	$ (43,400)