BP Midstream Partners (BPMP) 10-Q 9 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 08, 2018
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	BPMP
Entity Registrant Name	BP Midstream Partners LP
Entity Central Index Key	1,708,301
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Common Units
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		52,375,535
Subordinated Units
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		52,375,535

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 40,527	$ 32,694
Accounts receivable – third parties	217	188
Accounts receivable – related parties	9,258	9,481
Prepaid expenses	1,506	1,370
Other current assets	839	1,655
Total current assets	52,347	45,388
Equity method investments (Note 2)	470,074	487,999
Property, plant and equipment, net (Note 3)	68,815	69,488
Other assets	3,263	2,783
Total assets	594,499	605,658
Current liabilities
Short-term debt (Note 5)	0	15,000
Accounts payable – third parties	762	269
Accounts payable – related parties	1,641	2,270
Deferred revenue and credits	2,186	0
Accrued liabilities (Note 4)	3,139	4,481
Total current liabilities	7,728	22,020
Long-term portion of environmental remediation obligations	3,263	2,783
Total liabilities	10,991	24,803
Commitments and contingencies (Note 10)
EQUITY
Total partner's capital	250,021	238,525
Non-controlling interests	333,487	342,330
Total equity	583,508	580,855
Total liabilities and equity	594,499	605,658
Common Units | General Public
EQUITY
Common stock	829,903	824,613
Common Units | BP Holdco
EQUITY
Common stock	(46,640)	(47,141)
Subordinated Units | BP Holdco
EQUITY
Common stock	$ (533,242)	$ (538,947)

CONSOLIDATED BALANCE SHEEETS (P

CONSOLIDATED BALANCE SHEEETS (Parenthetical) - shares	Jun. 30, 2018	Dec. 31, 2017
General Public | Common Units
Common units outstanding (in shares)	47,794,358	47,794,358
Units issued (in shares)	47,794,358	47,794,358
BP Holdco | Common Units
Common units outstanding (in shares)	4,581,177	4,581,177
Units issued (in shares)	4,581,177	4,581,177
BP Holdco | Subordinated Units
Common units outstanding (in shares)	52,375,535	52,375,535
Units issued (in shares)	52,375,535	52,375,535

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue
Third parties	$ 766		$ 1,564
Related parties	28,169		53,990
Total revenue	28,935		55,554
Costs and expenses
Operating expenses – third parties	3,032		5,666
Operating expenses – related parties	1,026		1,988
Maintenance expenses – third parties	847		883
Maintenance expenses – related parties	24		44
Gain from disposition of property, plant and equipment	0		0
General and administrative – third parties	415		1,203
General and administrative – related parties	3,442		6,865
Depreciation	662		1,324
Property and other taxes	112		223
Total costs and expenses	9,560		18,196
Operating income	19,375		37,358
Income from equity method investments	20,842		43,681
Other loss	0		0
Interest expense, net	25		139
Income before income taxes	40,192		80,900
Income tax expense	0		0
Net income	40,192		80,900
Less: Net income attributable to non-controlling interests	9,722		19,891
Net income attributable to the Partnership	$ 30,470		$ 61,009
Limited Partners Common Units
Net income attributable to the Partnership per limited partner unit – basic and diluted (in dollars):
Net income per limited partnership unit, basic and diluted (in dollars per share)	$ 0.29		$ 0.58
Distributions declared per limited partner unit (in dollars, Note 7):
Distribution made per limited partner unit (in dollars per share)	0.2725		0.54
Limited Partners Subordinated Units
Net income attributable to the Partnership per limited partner unit – basic and diluted (in dollars):
Net income per limited partnership unit, basic and diluted (in dollars per share)	0.29		0.58
Distributions declared per limited partner unit (in dollars, Note 7):
Distribution made per limited partner unit (in dollars per share)	$ 0.2725		$ 0.54
Common Units Public
Weighted average number of limited partner units outstanding - basic and diluted (in millions):
Weighted average number of limited partner units outstanding (in dollars per share)	47.8		47.8
BP Holdco | Common Units
Weighted average number of limited partner units outstanding - basic and diluted (in millions):
Weighted average number of limited partner units outstanding (in dollars per share)	4.6		4.6
BP Holdco | Subordinated Units
Weighted average number of limited partner units outstanding - basic and diluted (in millions):
Weighted average number of limited partner units outstanding (in dollars per share)	52.4		52.4
Predecessor
Revenue
Third parties		$ 566		$ 1,474
Related parties		26,319		52,054
Total revenue		26,885		53,528
Costs and expenses
Operating expenses – third parties		1,830		3,318
Operating expenses – related parties		1,875		3,867
Maintenance expenses – third parties		729		1,289
Maintenance expenses – related parties		192		192
Gain from disposition of property, plant and equipment		(6)		(6)
General and administrative – third parties		(44)		44
General and administrative – related parties		982		2,361
Depreciation		662		1,332
Property and other taxes		46		154
Total costs and expenses		6,266		12,551
Operating income		20,619		40,977
Income from equity method investments		0		0
Other loss		312		488
Interest expense, net		0		0
Income before income taxes		20,307		40,489
Income tax expense		7,933		15,816
Net income		$ 12,374		$ 24,673

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Non-controlling Interests	Net Parent Investment	Common UnitsPartnershipGeneral Public	Common UnitsPartnershipBP Holdco	Subordinated UnitsPartnershipBP Holdco	General PartnerPartnership
Beginning Balance (Predecessor) at Dec. 31, 2016	$ 73,942	$ 0	$ 73,942	$ 0	$ 0	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income | Predecessor	24,673		24,673
Net transfers to Parent | Predecessor	(18,510)		(18,510)
Ending Balance (Predecessor) at Jun. 30, 2017	80,105	0	80,105	0	0	0	0
Beginning Balance at Dec. 31, 2017	580,855	342,330	0	824,613	(47,141)	(538,947)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change (Note 2)	(2,746)			(1,253)	(120)	(1,373)
Net income	80,900	19,891		27,836	2,669	30,504
Distributions to unitholders	(46,851)			(21,377)	(2,048)	(23,426)
Unit-based compensation	84			84
Distributions to non-controlling interests	(28,734)	(28,734)
Ending Balance at Jun. 30, 2018	$ 583,508	$ 333,487	$ 0	$ 829,903	$ (46,640)	$ (533,242)	$ 0

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net income	$ 80,900
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation	1,324
Deferred income taxes	0
Share-based compensation	84
Loss due to changes in fair value of allowance oil receivable	0
Gain from disposition of property, plant and equipment	0
Income from equity method investments	(43,681)
Distributions of earnings received from equity method investments	47,807
Changes in operating assets and liabilities
Accounts receivable – third parties	(29)
Accounts receivable – related parties	223
Allowance oil receivable	0
Prepaid expenses and other current assets	(136)
Accounts payable – third parties	493
Accounts payable – related parties	(629)
Deferred revenue and credits	2,186
Accrued liabilities	(705)
Long-term portion of environmental remediation obligations	0
Other liabilities	0
Net cash provided by operating activities	87,837
Cash flows from investing activities
Capital expenditures	(472)
Distributions in excess of earnings from equity method investments	11,053
Proceeds from disposition of property, plant and equipment	0
Net cash provided by (used in) investing activities	10,581
Cash flows from financing activities
Net transfers to Parent – prior to the IPO	0
Repayment of short-term debt	(15,000)
Distributions to unitholders	(46,851)
Distributions to non-controlling interests	(28,734)
Net cash used in financing activities	(90,585)
Net change in cash and cash equivalents	7,833
Cash and cash equivalents at beginning of the period	32,694
Cash and cash equivalents at end of the period	40,527
Non-cash investing transactions
Accrued capital expenditures	$ 198
Predecessor
Cash flows from operating activities
Net income		$ 24,673
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation		1,332
Deferred income taxes		539
Share-based compensation		104
Loss due to changes in fair value of allowance oil receivable		488
Gain from disposition of property, plant and equipment		(6)
Income from equity method investments		0
Distributions of earnings received from equity method investments		0
Changes in operating assets and liabilities
Accounts receivable – third parties		234
Accounts receivable – related parties		(5,258)
Allowance oil receivable		(761)
Prepaid expenses and other current assets		(71)
Accounts payable – third parties		169
Accounts payable – related parties		46
Deferred revenue and credits		0
Accrued liabilities		(648)
Long-term portion of environmental remediation obligations		(231)
Other liabilities		(162)
Net cash provided by operating activities		20,448
Cash flows from investing activities
Capital expenditures		(1,840)
Distributions in excess of earnings from equity method investments		0
Proceeds from disposition of property, plant and equipment		6
Net cash provided by (used in) investing activities		(1,834)
Cash flows from financing activities
Net transfers to Parent – prior to the IPO		(18,614)
Repayment of short-term debt		0
Distributions to unitholders		0
Distributions to non-controlling interests		0
Net cash used in financing activities		(18,614)
Net change in cash and cash equivalents		0
Cash and cash equivalents at beginning of the period		0
Cash and cash equivalents at end of the period		0
Non-cash investing transactions
Accrued capital expenditures		$ 0

Business and Basis of Presentat

Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation BP Midstream Partners LP (either individually or together with its subsidiaries, as the context requires, the “Partnership”) is a Delaware limited partnership formed on May 22, 2017 by BP Pipelines (North America) Inc. (“BP Pipelines”), an indirect wholly owned subsidiary of BP p.l.c. (“BP”), a “foreign private issuer” within the meaning of the Securities Exchange Act of 1934, as amended. On October 30, 2017, the Partnership completed its initial public offering (the "IPO") of common units representing limited partner interests. A total of 47,794,358 common units, including 5,294,358 common units pertaining to the exercise of the underwriters' over-allotment option, were issued to the public unitholders in connection with our IPO. Unless otherwise stated or the context otherwise indicates, all references to “we,” “our,” “us,” “Predecessor,” or similar expressions for time periods prior to the IPO refer to BP Midstream Partners LP Predecessor, which consisted of the historical assets and operations of the Predecessor Assets (as defined below). For time periods subsequent to the IPO, “we,” “our,” “us,” or similar expressions refer to the legal entity BP Midstream Partners LP. The term “our Parent” refers to BP Pipelines, any entity that wholly owns BP Pipelines, indirectly or directly, including BP and BP America Inc. (“BPA”), an indirect wholly owned subsidiary of BP, and any entity that is wholly owned by the aforementioned entities, excluding BP Midstream Partners LP Predecessor and the Partnership. Business We are a fee-based, growth-oriented master limited partnership formed by BP Pipelines to own, operate, develop and acquire pipelines and other midstream assets. Our assets consist of interests in entities that own crude oil, natural gas, refined products and diluent pipelines serving as key infrastructure for BP and other customers to transport onshore crude oil production to BP’s refinery in Whiting, Indiana (the “Whiting Refinery”) and offshore crude oil and natural gas production to key refining markets and trading and distribution hubs. Certain of our assets deliver refined products and diluent from the Whiting Refinery and other U.S. supply hubs to major demand centers. Our assets consist of the following: • BP Two Pipeline Company LLC, which owns the BP#2 crude oil pipeline system (“BP2”). • BP River Rouge Pipeline Company LLC, which owns the Whiting to River Rouge refined products pipeline system (“River Rouge”). • BP D-B Pipeline Company LLC, which owns the Diamondback diluent pipeline system (“Diamondback”). BP2, River Rouge, and Diamondback are located in the Midwest region of the United States, and together are referred to as the "Predecessor Assets" or the "Wholly Owned Assets". • A 28.5% ownership interest in Mars Oil Pipeline Company, LLC (“Mars”), which owns a major corridor crude oil pipeline system in the Gulf of Mexico. • A 20% managing member interest in Mardi Gras Transportation System Company, LLC (“Mardi Gras”), which holds the following investments in joint ventures located in the Gulf of Mexico: • A 56% ownership interest in Caesar Oil Pipeline Company, LLC (“Caesar”), • A 53% ownership interest in Cleopatra Gas Gathering Company, LLC (“Cleopatra”), • A 65% ownership interest in Proteus Oil Pipeline Company, LLC (“Proteus”), and, • A 65% ownership interest in Endymion Oil Pipeline Company, LLC (“Endymion”). • Together Endymion, Caesar, Cleopatra and Proteus are referred to as the “Mardi Gras Joint Ventures.” We generate the majority of our revenue by charging fees for the transportation of crude oil, refined products and diluent through our pipelines under long-term agreements with minimum volume commitments. We do not engage in the marketing and trading of any commodities. All of our operations are conducted in the United States, and all our long-lived assets are located in the United States. Our operations consist of one reportable segment. Certain businesses of ours are subject to regulation by various authorities including, but not limited to the Federal Energy Regulatory Commission ("FERC"). Regulatory bodies exercise statutory authority over matters such as common carrier tariffs, construction, rates and ratemaking and agreements with customers. Basis of Presentation Our condensed consolidated financial statements have been prepared under the rules and regulations of the Securities and Exchange Commission (“SEC”). These rules and regulations conform to the accounting principles contained in the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification, the single source of accounting principles generally accepted in the United States (“GAAP”). Certain information and footnote disclosures normally included in the annual consolidated financial statements have been condensed or omitted from these condensed consolidated financial statements. The condensed consolidated financial statements as of June 30, 2018, and for the three and six months ended June 30, 2018 and 2017, included herein, are unaudited. These financial statements include all known accruals and adjustments necessary, in the opinion of management, for a fair presentation of our consolidated financial position, results of operations and cash flows. Unless otherwise specified, all such adjustments are of a normal and recurring nature. The unaudited results of operations for the interim periods reported are not necessarily indicative of results to be expected for the full year. These unaudited condensed consolidated financial statements and other information included in this quarterly report on Form 10-Q should be read in conjunction with our audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2017 (the "2017 Annual Report"). Prior to the IPO, our financial position, results of operations and cash flows consisted of the Predecessor's operations, which represented a combined reporting entity. Subsequent to the IPO, our financial position, results of operations and cash flows consist of consolidated BP Midstream Partners LP activities and balances. All intercompany accounts and transactions within the financial statements have been eliminated for all periods presented. Prior to the IPO, our condensed consolidated statements of operations include expense allocations to the Predecessor for certain functions performed by our Parent on our behalf, including allocations of general corporate expenses related to finance, accounting, treasury, legal, information technology, human resources, shared services, government affairs, insurance, health, safety, security, employee benefits, incentives, severance and environmental functional support. The portion of expenses that are specifically identifiable to the Predecessor Assets are directly recorded to the Predecessor, with the remainder allocated on the basis of headcount, throughput volumes, miles of pipe and other measures. Our management believes the assumptions underlying the financial statements, including the assumptions regarding the allocation of general corporate expenses from our Parent, are reasonable. Nevertheless, the financial statements may not include all of the expenses that would have been incurred, had we been a stand-alone entity during the periods prior to the IPO and may not reflect our financial position, results of operations and cash flows, had we been a stand-alone entity during such periods. See Note 6 - Related Party Transactions . Prior to the IPO, the Predecessor Assets did not own or maintain separate bank accounts. Our Parent used a centralized approach to cash management and historically funded our operating and investing activities as needed within the boundaries of a documented funding agreement. Accordingly, cash held by our Parent at the corporate level was not allocated to us for any of the periods prior to the IPO. During such periods, we reflected the cash generated by our operations and expenses paid by our Parent on our behalf as a component of Net parent investment on our condensed consolidated balance sheets, and as a net distribution to our Parent on our condensed consolidated statements of cash flows. We also did not include any interest income on the net cash transfers to our Parent. In connection with the IPO, we established our own cash accounts for the funding of our operating and investing activities. All financial information presented for the periods after the IPO represents the condensed consolidated results of operations, financial position and cash flows of the Partnership. Accordingly: • Our condensed consolidated statements of operations for the three and six months ended June 30, 2018 and condensed consolidated statement cash flows for the six months ended June 30, 2018 consist of the consolidated results of the Partnership. Our condensed consolidated statements of operations for the three and six months ended June 30, 2017 and condensed consolidated statement cash flows for the six months ended June 30, 2017 consist of the combined results of the Predecessor. • Our condensed consolidated balance sheets at June 30, 2018 and December 31, 2017 consist of the consolidated balances of the Partnership. • Our condensed consolidated statement of changes in equity for the six months ended June 30, 2018 consist of the consolidated results for the Partnership. Our condensed consolidated statement of changes in equity for the six months ended June 30, 2017 consists of the combined results of the Predecessor. Summary of Significant Accounting Policies There have been no significant changes to our accounting policies as disclosed in Note 2 - Summary of Significant Accounting Policies in our 2017 Annual Report. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update ("ASU") 2014-09, "Revenue from Contracts with Customers (Topic 606)". ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The core principle of the new standard is that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, the FASB issued ASU 2015-14 to defer the adoption date for ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period for public business entities and to annual reporting periods beginning after December 15, 2018, and interim reporting periods within annual reporting periods beginning after December 15, 2019 for all other entities. This ASU is effective as of January 1, 2019 for an emerging growth company ("EGC"). We expect to transition from EGC status to large accelerated as of December 31, 2018, as such we will reflect the adoption in our on Annual Report on Form 10-K for the year ended December 31, 2018. ASU 2014-09 was further amended in March 2016 by the provisions of ASU 2016-08, "Principal versus Agent Considerations (Reporting Revenue Gross versus Net)," in April 2016 by the provisions of ASU 2016-10, "Identifying Performance Obligations and Licensing", in May 2016 by the provisions of ASU 2016-12, "Narrow-Scope Improvements and Practical Expedients", in December 2016 by the provisions of ASU 2016-20, "Technical Corrections to Topic 606, Revenue from Contracts with Customers" and in September 2017 by the provisions of ASU 2017-13, "Revenue Recognition (Topic 605) and Revenue from Contracts with Customers (Topic 606)." We have evaluated the impact that the adoption of the provisions under Topic 606 will have on our revenue contracts, consolidated financial statements and the accompanying notes. Based upon our assessment, the new standard may impact the timing of revenue recognition, but we do not expect significant changes to the amounts recognized for each reporting period. We will adopt the new standard under the modified retrospective transition method by December 31, 2018. In February 2016, the FASB issued ASU 2016-02, "Leases", which improves transparency and comparability among organizations by requiring lessees to recognize a lease liability and a corresponding lease asset for virtually all lease contracts. It also requires additional disclosures about leasing arrangements. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years for public business entities and for annual reporting periods beginning after December 15, 2019 and interim reporting periods beginning after December 15, 2020 for all other entities. This ASU is effective as of January 1, 2019 for us, as we expect to transition from EGC status to large accelerated as of December 31, 2018. In January 2018, the FASB issued ASU 2018-01, "Leases (Topic 842), Land Easement Practical Expedient for Transition to Topic 842". This ASU permits an entity to continue to apply its current accounting policy for land easements that existed before the effective date of Topic 842. Once an entity adopts Topic 842, it would apply prospectively to all new (or modified) land easements to determine whether the arrangement contains a lease. Topic 842 requires adoption by application of a modified retrospective transition approach and is effective for us on the same effective date as ASU 2016-02. We are currently evaluating the impact the adoption of these standards will have on our consolidated financial statements and the accompanying notes and we will have our assessment completed prior to December 31, 2018. For additional information on accounting pronouncements issued prior to December 2017, see Note 2 - Summary of Significant Accounting Policies in our 2017 Annual Report.

Equity Method Investments

Equity Method Investments	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments We account for our ownership interests in Mars and the Mardi Gras Joint Ventures using the equity method for financial reporting purposes. Our financial results include our proportionate share of the Mars’ and Mardi Gras Joint Ventures’ net income, which is reflected in Income from equity method investments on the condensed consolidated statements of operations. Summarized financial information for each of our equity method investments on a 100% basis is as follows: Three Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Statement of operations data Revenues $ 51,867 $ 9,832 $ 5,222 $ 8,305 $ 8,992 $ 32,351 $ 84,218 Operating expenses 21,381 3,548 2,419 2,924 3,486 12,377 33,758 Net income 30,489 6,284 2,803 5,381 5,616 20,084 50,573 Six Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Statement of operations data Revenues $ 109,042 $ 21,435 $ 10,983 $ 16,905 $ 18,428 $ 67,751 $ 176,793 Operating expenses 43,029 7,427 4,691 6,271 8,228 26,617 69,646 Net income 66,023 14,008 6,292 10,634 10,420 41,354 107,377 The table below summarizes the balances and activities related to each of our equity method investments that we recorded for the three and six months ended June 30, 2018: Three Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Beginning Balance $ 60,117 $ 121,795 $ 122,446 $ 85,553 $ 86,574 $ 416,368 $ 476,485 Distributions (10,118 ) (4,480 ) (2,385 ) (5,070 ) (5,200 ) (17,135 ) (27,253 ) Income from equity method investments 8,689 3,519 1,486 3,498 3,650 12,153 20,842 Ending Balance $ 58,688 $ 120,834 $ 121,547 $ 83,981 $ 85,024 $ 411,386 $ 470,074 Six Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Beginning Balance $ 65,561 $ 123,586 $ 123,512 $ 87,144 $ 88,196 $ 422,438 $ 487,999 Cumulative effect of accounting change* (2,746 ) — — — — — (2,746 ) Distributions (22,943 ) (10,597 ) (5,300 ) (10,075 ) (9,945 ) (35,917 ) (58,860 ) Income from equity method investments 18,816 7,845 3,335 6,912 6,773 24,865 43,681 Ending Balance $ 58,688 $ 120,834 $ 121,547 $ 83,981 $ 85,024 $ 411,386 $ 470,074 * The financial results of Mars reflect the adoption of ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)" on January 1, 2018 under the modified retrospective transition method through a cumulative adjustment to equity. Our impact from this accounting change to our Mars investment was $(2,746) , offset to partners' capital. The Mardi Gras Joint Ventures will adopt this ASU on January 1, 2019.

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consisted of the following: June 30, December 31, 2018 2017 Land $ 155 $ 155 Right-of-way assets 1,380 1,380 Buildings and improvements 12,032 12,032 Pipelines and equipment 92,208 92,083 Other 510 509 Construction in progress 587 67 Property, plant and equipment, gross 106,872 106,226 Less: Accumulated depreciation (38,057 ) (36,738 ) Property, plant and equipment, net $ 68,815 $ 69,488

Accrued Liabilities

Accrued Liabilities	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consisted of the following: June 30, December 31, 2018 2017 Current portion of environmental remediation obligations $ 839 $ 1,655 Other accrued liabilities 2,300 2,826 Accrued liabilities $ 3,139 $ 4,481 Accrued interest and fees related to our credit facility were $155 and $159 as of June 30, 2018 and December 31, 2017 , respectively, included in Other accrued liabilities. See Note 5 - Debt for further discussion of accrued interest and fees on debt with our related party.

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt On October 30, 2017, the Partnership entered into a $600.0 million unsecured revolving credit facility agreement (the “Credit Facility”) with an affiliate of BP. A summary of certain key terms of the Credit Facility is included in Note 7 - Debt in our 2017 Annual Report. On May 4, 2018, the Partnership repaid outstanding borrowings under the Credit Facility. This short-term debt had a principal balance of $15.0 million at the time of repayment and the repayment was made using cash on hand. There were $0 of outstanding borrowings under the Credit Facility at June 30, 2018 and $15 million outstanding at December 31, 2017. Interest charges and fees related to the Credit Facility were $0.2 million and $0.4 million for the three and six months ended June 30, 2018 respectively, and $0 for the three and six months ended June 30, 2017. For the three and six months ended June 30, 2018, the weighted average interest rate for the Credit Facility was 2.2% . This facility includes customary fees, including a commitment fee of 0.10% and a utilization fee of 0.20% per annum.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Related party transactions include transactions with our Parent and our Parent’s affiliates, including those entities in which our Parent has an ownership interest but does not have control. In addition to the fixed loss allowance arrangements discussed in Note 2- Summary of Significant Accounting Policies in our 2017 Annual Report and the Credit Facility discussed above, we have entered into the following transactions with our related parties: Omnibus Agreement In connection with the IPO, the Partnership entered into an omnibus agreement with BP Pipelines and certain of its affiliates, including BP Midstream Partners GP LLC (our "general partner"). This agreement addresses, among other things, (i) the Partnership's obligation to pay an annual fee for general and administrative services provided by BP Pipelines and its affiliates, (ii) the Partnership's obligation to reimburse BP Pipelines for personnel and other costs related to the direct operation, management and maintenance of the assets and (iii) the Partnership's obligation to reimburse BP Pipelines for services and certain direct or allocated costs and expenses incurred by BP Pipelines or its affiliates on behalf of the Partnership. Pursuant to the omnibus agreement, BP Pipelines will indemnify the Partnership and fund the costs of required remedial action for its known historical and legacy spills and releases and other environmental and litigation claims identified in the omnibus agreement. BP Pipelines will also indemnify the Partnership with respect to subsidiaries for which it is the operator for certain title defects and for failures to obtain certain consents and permits necessary to conduct its business for one year following the closing of our IPO. Further, the omnibus agreement addresses the granting of a license from BPA to the Partnership with respect to use of certain BP trademarks and trade name. Cash Management Program Prior to the IPO, we did not have our standalone cash accounts but participated in our Parent’s centralized cash management and funding system. See Note 1 - Business and Basis of Presentation for further discussion. In connection with the IPO, we established our own cash accounts for the funding of our operating and investing activities but continued to participate in our Parent’s centralized cash management and funding system. Related Party Revenue We provide crude oil, refined products and diluent transportation services to related parties and generate revenue through published tariffs. We have commercial arrangements with BP Products North America, Inc. ("BP Products") that include minimum volume commitments. Under these fee-based agreements, we provide transportation services to BP Products and BP Products has committed to pay us for minimum volumes of crude oil, refined products and diluent, regardless of whether such volumes are physically shipped by BP Products through our pipelines during the term of the agreements. See Note 8 - Related Party Transactions in our 2017 Annual Report for further discussion regarding these agreements. We also have a fixed loss allowance (“FLA”) arrangement with BP Products, which provides us with additional income. See Note 8 - Fair Value Measurements for further information. Our revenue from related parties was $28,169 and $53,990 for the three and six months ended June 30, 2018 respectively, and $ 26,319 and $52,054 for the three and six months ended June 30, 2017, respectively. We did no t recognize any deficiency revenue under the throughput and deficiency agreements with BP Products for the three and six months ended June 30, 2018, respectively and for the three and six months ended June 30, 2017, respectively. We recorded $2,186 and $0 in Deferred revenue and credits on our condensed consolidated balance sheets at June 30, 2018 and December 31, 2017, respectively. Related Party Expenses All employees performing services on behalf of our operations are employees of our Parent. Our Parent also procures our insurance policies on our behalf and performs certain general corporate functions for us related to finance, accounting, treasury, legal, information technology, human resources, shared services, government affairs, insurance, health, safety, security, employee benefits, incentives, severance and environmental functional support. Personnel and operating costs incurred by our Parent on our behalf are included in either Operating expenses – related parties or General and administrative – related parties in the condensed consolidated statements of operations, depending on the nature of the service provided. Prior to our IPO, we were allocated operating and indirect general corporate expenses incurred by our Parent. See Note 1 - Business and Basis of Presentation for a summary of the allocation methodology. Subsequent to the IPO, we pay BP Pipelines an annual fee of $13,300 in the form of monthly installments under the omnibus agreement for general and administrative services provided by BP Pipelines and its affiliates. We also reimburse BP Pipelines for personnel and other costs related to the direct operation, management and maintenance of the assets and services and certain direct or allocated costs and expenses incurred by BP Pipelines or its affiliates on our behalf pursuant to the terms in the omnibus agreement. For the three and six months ended June 30, 2018 and 2017, we recorded the following amounts for related party expenses, which also included the expenses related to share-based compensation discussed below: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Predecessor Predecessor Operating expenses—related parties $ 1,026 $ 1,875 $ 1,988 $ 3,867 Maintenance expenses—related parties 24 192 44 192 General and administrative—related parties 3,442 982 6,865 2,361 Total costs and expenses—related parties $ 4,492 $ 3,049 $ 8,897 $ 6,420 Share-based Compensation Certain employees of our Parent supporting our operations were historically granted awards under share option plans and equity-settled employee share plans. Prior to the IPO, these share-based compensation costs were allocated to us as part of the cost allocations from our Parent. These costs were $ 61 and $104 for the three and six months ended June 30, 2017, respectively, recorded in General and administrative – related parties on the condensed consolidated statements of operations. Subsequent to the IPO, the share-based compensation related to the employees of our Parent who provide services to us is charged to the Partnership pursuant to the terms of the omnibus agreement. The Partnership also issued its own unit-based compensation under our long term incentive plan. See Note 11 - Unit-Based Compensation. Non-controlling Interests We control and consolidate Mardi Gras via an agreement between us and our Parent, under which we have the right to vote 100% of Mardi Gras’ ownership interests in each of the Mardi Gras Joint Ventures. Non-controlling interests consist of the 80% ownership interest in Mardi Gras retained by our Parent upon the completion of the IPO and held at June 30, 2018. Net income attributable to non-controlling interests is the product of the non-controlling interests ownership percentage and the net income of Mardi Gras. We report Non-controlling interests as a separate component of equity on our condensed consolidated balance sheets and Net income attributable to non-controlling interests on our condensed consolidated statements of operations.

Net Income Per Limited Partner

Net Income Per Limited Partner Unit	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income Per Limited Partner Unit	Net Income Per Limited Partner Unit On February 15, 2018, we paid a prorated quarterly cash distribution of $0.1798 per limited partner unit to unitholders of record on February 1, 2018, for the period from October 30 through December 31, 2017. On May 15, 2018, we paid a quarterly cash distribution of $0.2675 per limited partner unit to unitholders of record on May 1, 2018, for the period from January 1 through March 31, 2018. On July 18, 2018, the board of directors of our general partner declared a quarterly cash distribution of $0.2725 per limited partner unit to unitholders of record on August 1, 2018, for the period from April 1 through June 30, 2018. This distribution will be paid on August 15, 2018. Net income per limited partner unit is only calculated for the three and six months ended June 30, 2018 as no units were outstanding in the same periods of 2017. The following tables show the allocation of net income to arrive at net income per limited partner unit for the three and six months ended June 30, 2018: Three Months Ended June 30, Six Months Ended June 30, 2018 2018 Net income attributable to the Partnership $ 30,470 $ 61,009 Less: Incentive distribution rights currently held by the General Partner — — Limited partners' distribution declared on common units 14,272 28,282 Limited partners' distribution declared on subordinated units 14,272 28,282 Net income attributable to the Partnership in excess of distributions $ 1,926 $ 4,445 Three Months Ended June 30, 2018 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ — $ 14,272 $ 14,272 $ 28,544 Net income attributable to the Partnership in excess of distributions — 963 963 1,926 Net income attributable to the Partnership $ — $ 15,235 $ 15,235 $ 30,470 Weighted average units outstanding: Basic 52,376 52,376 104,752 Diluted 52,382 52,376 104,758 Net income per limited partner unit (in dollars): Basic $ 0.29 $ 0.29 Diluted $ 0.29 $ 0.29 Six Months Ended June 30, 2018 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ — $ 28,282 $ 28,282 $ 56,564 Net income attributable to the Partnership in excess of distributions $ — $ 2,223 $ 2,222 4,445 Net income attributable to the Partnership $ — $ 30,505 $ 30,504 $ 61,009 Weighted average units: Basic 52,376 52,376 104,752 Diluted 52,382 52,376 104,758 Net income per limited partner unit (in dollars): Basic $ 0.58 $ 0.58 Diluted $ 0.58 $ 0.58

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We measure assets and liabilities requiring fair value presentation and disclose such amounts according to the quality of valuation inputs under the fair value hierarchy. The carrying amounts of our financial instruments included in current assets and current liabilities approximate fair value due to their short-term nature and maturity. Our tariff for crude oil transportation on BP2 includes a fixed percentage FLA per barrel, which is a separate fee under the applicable crude oil tariff to cover evaporation and other loss in transit. In the periods presented, all our revenue on BP2 was generated from services to our Parent. We recognize FLA income in Revenue - related parties in the condensed consolidated statements of operations during the periods when commodities are transported. Allowance oil receivable incurred prior to October 1, 2017 contained an embedded derivative, which we recorded at fair value on the condensed consolidated balance sheets together with its host arrangement. We recorded the changes in fair value in Other income (loss) on the condensed consolidated statements of operations. Allowance oil receivable balance incurred prior to October 1, 2017, including the embedded derivative, was classified as Level 2 in the fair value hierarchy. Such balances were entirely settled upon the IPO. Allowance oil receivable incurred subsequent to October 1, 2017 no longer contains an embedded derivative or results in gain or loss related to the change in its fair value pursuant to the revised settlement price determination in a related party agreement between us and our Parent. We now settle the allowance oil at the end of each period; therefore, the balances are entirely recorded in Accounts receivable - related parties after October 1, 2017. In the three and six months ended June 30, 2018, we recognized FLA income of $2,860 and $5,000 , respectively. In the three and six months ended June 30, 2017, we recognized FLA income of $2,061 and $3,997 , respectively, and a loss due to the changes in fair value of $312 and $488 , respectively, related to the FLA arrangement with our Parent.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Prior to our IPO, the Predecessor was a part of BPA and was included in the income tax returns of BPA. Our tax provision prior to the IPO was prepared on a separate return basis, as if the Predecessor was a separate group of companies under common ownership. The Predecessor recorded income tax expense of $7,933 and $ 15,816 for the three and six months ended June 30, 2017, respectively. BP Midstream Partners LP is not a taxable entity for U.S. federal and state income tax purposes. Taxes on our net income are generally borne by our partners through the allocation of taxable income. The condensed consolidated financial statements, therefore, do not include a provision for income tax after the IPO.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings From time to time, we are party to ongoing legal proceedings in the ordinary course of business. For each of our outstanding legal matters, if any, we evaluate the merits of the case, our exposure to the matter, possible legal or settlement strategies and the likelihood of an unfavorable outcome. While the outcome of these proceedings cannot be predicted with certainty, we do not believe the results of these proceedings, individually or in the aggregate, will have a material adverse effect on our business, financial condition, results of operations or liquidity. Indemnification Under our omnibus agreement, our Parent will indemnify us for certain environmental liabilities, litigation and other matters attributable to the ownership or operation of our assets prior to the closing of the IPO. For the purposes of determining the indemnified amount of any loss suffered or incurred by the Partnership, the Partnership’s ownership of 28.5% in Mars, and 20% in Mardi Gras, and Mardi Gras’ 56% ownership in Caesar, 53% ownership in Cleopatra, 65% ownership in Endymion and 65% ownership in Proteus will be taken into account. Indemnification for certain identified environmental liabilities is subject to a cap of $25.0 million without any deductible. Other matters covered by the omnibus agreement are subject to a cap of $15.0 million and an aggregate deductible of $0.5 million before we are entitled to indemnification. Indemnification for any unknown environmental liabilities is limited to liabilities due to occurrences prior to the closing of the IPO and that are identified before the third anniversary of the closing of the IPO. Environmental Matters We are subject to federal, state, and local environmental laws and regulations. We record provisions for environmental liabilities based on management’s best estimates, using all information that is available at the time. In making environmental liability estimations, we consider the material effect of environmental compliance, pending legal actions against us and potential third-party liability claims. Often, as the remediation evaluation and effort progresses, additional information is obtained, requiring revisions to estimated costs. We are indemnified by our Parent under the omnibus agreement against environmental cleanup costs for incidents that occurred prior to the IPO. Subsequent to the IPO, revisions to the estimated environmental liability for conditions that are not indemnified under the omnibus agreement with our Parent are reflected in our condensed consolidated statements of operations in the year in which they are probable and reasonably estimable. We accrued $4,102 and $4,438 for environmental liabilities at June 30, 2018 and December 31, 2017, respectively. The balances are related to incidents that occurred prior to the IPO and are entirely indemnified by our Parent. As a result, we recorded corresponding indemnification assets of $4,102 and $4,438 on the condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017.

Unit-Based Compensation

Unit-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Unit-Based Compensation	Unit-Based Compensation Long-Term Incentive Plan Our general partner has adopted the BP Midstream Partners LP 2017 Long Term Incentive Plan (the “LTIP”). Awards under the LTIP are available for eligible officers, directors, employees and consultants of the general partner and its affiliates, who perform services for the Partnership. The LTIP allows the Partnership to grant unit options, unit appreciation rights, restricted units, phantom units, unit awards, cash awards, performance awards, distribution equivalent rights, substitute awards and other unit-based awards. The maximum aggregate number of common units that may be issued pursuant to the awards granted under the LTIP shall not exceed 5,502,271 , subject to proportionate adjustment in the event of unit splits and similar events. Unit-Based Awards under the LTIP The following is a summary of phantom unit award activities of the Partnership’s common units for the six months ended June 30, 2018: Phantom Units Number of Units (in units) Weighted Average Grant Date Fair Value per Unit (in dollars) Outstanding at December 31, 2017 8,468 $ 17.48 Granted 3,737 20.07 Outstanding at June 30, 2018 12,205 $ 18.27 Vested at June 30, 2018 — — For the three and six months ended June 30, 2018, total compensation expense recognized for phantom unit awards was $45 and $ 84 , respectively. The unrecognized compensation cost related to phantom unit awards was $120 at June 30, 2018, which is expected to be recognized over a weighted average period of 0.5 years. There were no forfeitures for the six months ended June 30, 2018.

Variable Interest Entity

Variable Interest Entity	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entity	Variable Interest Entity We control and consolidate our variable interest entity Mardi Gras because we are the primary beneficiary. Mardi Gras holds equity interests in the Mardi Gras Joint Ventures and accounts for them as equity method investments. Mardi Gras does not have any other operations or activities. See Note 15 - Variable Interest Entity in our 2017 Annual Report for further discussion. The financial position of Mardi Gras at June 30, 2018 and December 31, 2017, its financial performance for the three and six months ended June 30, 2018 and 2017 and cash flows for the six months ended June 30, 2018 and 2017, as reflected in our condensed consolidated financial statements, are as follows: June 30, 2018 December 31, 2017 Balance sheet Equity method investments $ 411,386 $ 422,438 Non-controlling interests 333,487 342,330 Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Statement of operations Income from equity method investments $ 12,153 * $ 24,865 * Less: Net income attributable to non-controlling interests 9,722 * 19,891 * Net impact on Net income attributable to the Partnership $ 2,431 * $ 4,974 * * Information is not applicable as the interest in Mardi Gras was contributed to the Partnership on October 30, 2017. Six Months Ended June 30, 2018 2017 Statement of cash flows Cash flows from operating activities Distributions of earnings received from equity method investments $ 24,865 * Cash flows from investing activities Distribution in excess of earnings from equity method investments 11,053 * Cash flows from financing activities Distributions to non-controlling interests (28,734 ) * Net change on BPMP's cash and cash equivalents $ 7,184 * * Information is not applicable as the interest in Mardi Gras was contributed to the Partnership on October 30, 2017.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events We have evaluated subsequent events through the issuance of these condensed consolidated financial statements. Based on this evaluation, it was determined that no subsequent events occurred, other than the item noted below, that require recognition or disclosure in the condensed consolidated financial statements. Cash Distribution On July 18, 2018, we declared a cash distribution of $0.2725 per limited partner unit to unitholders of record on August 1, 2018, for the three months ended June 30, 2018. The distribution will be paid on August 15, 2018 and will total $28.5 million , with $13.0 million being distributed to our non-affiliated common unitholders and $15.5 million being distributed to BP Midstream Partners Holdings LLC ("BP Holdco") in respect of its ownership of our common and subordinated units.

Business and Basis of Present20

Business and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Our condensed consolidated financial statements have been prepared under the rules and regulations of the Securities and Exchange Commission (“SEC”). These rules and regulations conform to the accounting principles contained in the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification, the single source of accounting principles generally accepted in the United States (“GAAP”). Certain information and footnote disclosures normally included in the annual consolidated financial statements have been condensed or omitted from these condensed consolidated financial statements. The condensed consolidated financial statements as of June 30, 2018, and for the three and six months ended June 30, 2018 and 2017, included herein, are unaudited. These financial statements include all known accruals and adjustments necessary, in the opinion of management, for a fair presentation of our consolidated financial position, results of operations and cash flows. Unless otherwise specified, all such adjustments are of a normal and recurring nature. The unaudited results of operations for the interim periods reported are not necessarily indicative of results to be expected for the full year. These unaudited condensed consolidated financial statements and other information included in this quarterly report on Form 10-Q should be read in conjunction with our audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2017 (the "2017 Annual Report"). Prior to the IPO, our financial position, results of operations and cash flows consisted of the Predecessor's operations, which represented a combined reporting entity. Subsequent to the IPO, our financial position, results of operations and cash flows consist of consolidated BP Midstream Partners LP activities and balances. All intercompany accounts and transactions within the financial statements have been eliminated for all periods presented. Prior to the IPO, our condensed consolidated statements of operations include expense allocations to the Predecessor for certain functions performed by our Parent on our behalf, including allocations of general corporate expenses related to finance, accounting, treasury, legal, information technology, human resources, shared services, government affairs, insurance, health, safety, security, employee benefits, incentives, severance and environmental functional support. The portion of expenses that are specifically identifiable to the Predecessor Assets are directly recorded to the Predecessor, with the remainder allocated on the basis of headcount, throughput volumes, miles of pipe and other measures. Our management believes the assumptions underlying the financial statements, including the assumptions regarding the allocation of general corporate expenses from our Parent, are reasonable. Nevertheless, the financial statements may not include all of the expenses that would have been incurred, had we been a stand-alone entity during the periods prior to the IPO and may not reflect our financial position, results of operations and cash flows, had we been a stand-alone entity during such periods. See Note 6 - Related Party Transactions . Prior to the IPO, the Predecessor Assets did not own or maintain separate bank accounts. Our Parent used a centralized approach to cash management and historically funded our operating and investing activities as needed within the boundaries of a documented funding agreement. Accordingly, cash held by our Parent at the corporate level was not allocated to us for any of the periods prior to the IPO. During such periods, we reflected the cash generated by our operations and expenses paid by our Parent on our behalf as a component of Net parent investment on our condensed consolidated balance sheets, and as a net distribution to our Parent on our condensed consolidated statements of cash flows. We also did not include any interest income on the net cash transfers to our Parent. In connection with the IPO, we established our own cash accounts for the funding of our operating and investing activities. All financial information presented for the periods after the IPO represents the condensed consolidated results of operations, financial position and cash flows of the Partnership. Accordingly: • Our condensed consolidated statements of operations for the three and six months ended June 30, 2018 and condensed consolidated statement cash flows for the six months ended June 30, 2018 consist of the consolidated results of the Partnership. Our condensed consolidated statements of operations for the three and six months ended June 30, 2017 and condensed consolidated statement cash flows for the six months ended June 30, 2017 consist of the combined results of the Predecessor. • Our condensed consolidated balance sheets at June 30, 2018 and December 31, 2017 consist of the consolidated balances of the Partnership. • Our condensed consolidated statement of changes in equity for the six months ended June 30, 2018 consist of the consolidated results for the Partnership. Our condensed consolidated statement of changes in equity for the six months ended June 30, 2017 consists of the combined results of the Predecessor.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update ("ASU") 2014-09, "Revenue from Contracts with Customers (Topic 606)". ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The core principle of the new standard is that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, the FASB issued ASU 2015-14 to defer the adoption date for ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period for public business entities and to annual reporting periods beginning after December 15, 2018, and interim reporting periods within annual reporting periods beginning after December 15, 2019 for all other entities. This ASU is effective as of January 1, 2019 for an emerging growth company ("EGC"). We expect to transition from EGC status to large accelerated as of December 31, 2018, as such we will reflect the adoption in our on Annual Report on Form 10-K for the year ended December 31, 2018. ASU 2014-09 was further amended in March 2016 by the provisions of ASU 2016-08, "Principal versus Agent Considerations (Reporting Revenue Gross versus Net)," in April 2016 by the provisions of ASU 2016-10, "Identifying Performance Obligations and Licensing", in May 2016 by the provisions of ASU 2016-12, "Narrow-Scope Improvements and Practical Expedients", in December 2016 by the provisions of ASU 2016-20, "Technical Corrections to Topic 606, Revenue from Contracts with Customers" and in September 2017 by the provisions of ASU 2017-13, "Revenue Recognition (Topic 605) and Revenue from Contracts with Customers (Topic 606)." We have evaluated the impact that the adoption of the provisions under Topic 606 will have on our revenue contracts, consolidated financial statements and the accompanying notes. Based upon our assessment, the new standard may impact the timing of revenue recognition, but we do not expect significant changes to the amounts recognized for each reporting period. We will adopt the new standard under the modified retrospective transition method by December 31, 2018. In February 2016, the FASB issued ASU 2016-02, "Leases", which improves transparency and comparability among organizations by requiring lessees to recognize a lease liability and a corresponding lease asset for virtually all lease contracts. It also requires additional disclosures about leasing arrangements. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years for public business entities and for annual reporting periods beginning after December 15, 2019 and interim reporting periods beginning after December 15, 2020 for all other entities. This ASU is effective as of January 1, 2019 for us, as we expect to transition from EGC status to large accelerated as of December 31, 2018. In January 2018, the FASB issued ASU 2018-01, "Leases (Topic 842), Land Easement Practical Expedient for Transition to Topic 842". This ASU permits an entity to continue to apply its current accounting policy for land easements that existed before the effective date of Topic 842. Once an entity adopts Topic 842, it would apply prospectively to all new (or modified) land easements to determine whether the arrangement contains a lease. Topic 842 requires adoption by application of a modified retrospective transition approach and is effective for us on the same effective date as ASU 2016-02. We are currently evaluating the impact the adoption of these standards will have on our consolidated financial statements and the accompanying notes and we will have our assessment completed prior to December 31, 2018. For additional information on accounting pronouncements issued prior to December 2017, see Note 2 - Summary of Significant Accounting Policies in our 2017 Annual Report.

Equity Method Investments (Tabl

Equity Method Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Equity Method Investments	Summarized financial information for each of our equity method investments on a 100% basis is as follows: Three Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Statement of operations data Revenues $ 51,867 $ 9,832 $ 5,222 $ 8,305 $ 8,992 $ 32,351 $ 84,218 Operating expenses 21,381 3,548 2,419 2,924 3,486 12,377 33,758 Net income 30,489 6,284 2,803 5,381 5,616 20,084 50,573 Six Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Statement of operations data Revenues $ 109,042 $ 21,435 $ 10,983 $ 16,905 $ 18,428 $ 67,751 $ 176,793 Operating expenses 43,029 7,427 4,691 6,271 8,228 26,617 69,646 Net income 66,023 14,008 6,292 10,634 10,420 41,354 107,377 The table below summarizes the balances and activities related to each of our equity method investments that we recorded for the three and six months ended June 30, 2018: Three Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Beginning Balance $ 60,117 $ 121,795 $ 122,446 $ 85,553 $ 86,574 $ 416,368 $ 476,485 Distributions (10,118 ) (4,480 ) (2,385 ) (5,070 ) (5,200 ) (17,135 ) (27,253 ) Income from equity method investments 8,689 3,519 1,486 3,498 3,650 12,153 20,842 Ending Balance $ 58,688 $ 120,834 $ 121,547 $ 83,981 $ 85,024 $ 411,386 $ 470,074 Six Months Ended June 30, 2018 Mardi Gras Joint Ventures Mars Caesar Cleopatra Proteus Endymion Total Mardi Gras Joint Ventures Total Beginning Balance $ 65,561 $ 123,586 $ 123,512 $ 87,144 $ 88,196 $ 422,438 $ 487,999 Cumulative effect of accounting change* (2,746 ) — — — — — (2,746 ) Distributions (22,943 ) (10,597 ) (5,300 ) (10,075 ) (9,945 ) (35,917 ) (58,860 ) Income from equity method investments 18,816 7,845 3,335 6,912 6,773 24,865 43,681 Ending Balance $ 58,688 $ 120,834 $ 121,547 $ 83,981 $ 85,024 $ 411,386 $ 470,074 * The financial results of Mars reflect the adoption of ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)" on January 1, 2018 under the modified retrospective transition method through a cumulative adjustment to equity. Our impact from this accounting change to our Mars investment was $(2,746) , offset to partners' capital. The Mardi Gras Joint Ventures will adopt this ASU on January 1, 2019.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Components of Property, Plant and Equipment	Property, plant and equipment consisted of the following: June 30, December 31, 2018 2017 Land $ 155 $ 155 Right-of-way assets 1,380 1,380 Buildings and improvements 12,032 12,032 Pipelines and equipment 92,208 92,083 Other 510 509 Construction in progress 587 67 Property, plant and equipment, gross 106,872 106,226 Less: Accumulated depreciation (38,057 ) (36,738 ) Property, plant and equipment, net $ 68,815 $ 69,488

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following: June 30, December 31, 2018 2017 Current portion of environmental remediation obligations $ 839 $ 1,655 Other accrued liabilities 2,300 2,826 Accrued liabilities $ 3,139 $ 4,481

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	For the three and six months ended June 30, 2018 and 2017, we recorded the following amounts for related party expenses, which also included the expenses related to share-based compensation discussed below: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Predecessor Predecessor Operating expenses—related parties $ 1,026 $ 1,875 $ 1,988 $ 3,867 Maintenance expenses—related parties 24 192 44 192 General and administrative—related parties 3,442 982 6,865 2,361 Total costs and expenses—related parties $ 4,492 $ 3,049 $ 8,897 $ 6,420

Net Income Per Limited Partne25

Net Income Per Limited Partner Unit (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share	The following tables show the allocation of net income to arrive at net income per limited partner unit for the three and six months ended June 30, 2018: Three Months Ended June 30, Six Months Ended June 30, 2018 2018 Net income attributable to the Partnership $ 30,470 $ 61,009 Less: Incentive distribution rights currently held by the General Partner — — Limited partners' distribution declared on common units 14,272 28,282 Limited partners' distribution declared on subordinated units 14,272 28,282 Net income attributable to the Partnership in excess of distributions $ 1,926 $ 4,445 Three Months Ended June 30, 2018 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ — $ 14,272 $ 14,272 $ 28,544 Net income attributable to the Partnership in excess of distributions — 963 963 1,926 Net income attributable to the Partnership $ — $ 15,235 $ 15,235 $ 30,470 Weighted average units outstanding: Basic 52,376 52,376 104,752 Diluted 52,382 52,376 104,758 Net income per limited partner unit (in dollars): Basic $ 0.29 $ 0.29 Diluted $ 0.29 $ 0.29 Six Months Ended June 30, 2018 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ — $ 28,282 $ 28,282 $ 56,564 Net income attributable to the Partnership in excess of distributions $ — $ 2,223 $ 2,222 4,445 Net income attributable to the Partnership $ — $ 30,505 $ 30,504 $ 61,009 Weighted average units: Basic 52,376 52,376 104,752 Diluted 52,382 52,376 104,758 Net income per limited partner unit (in dollars): Basic $ 0.58 $ 0.58 Diluted $ 0.58 $ 0.58

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Phantom Units Activity	The following is a summary of phantom unit award activities of the Partnership’s common units for the six months ended June 30, 2018: Phantom Units Number of Units (in units) Weighted Average Grant Date Fair Value per Unit (in dollars) Outstanding at December 31, 2017 8,468 $ 17.48 Granted 3,737 20.07 Outstanding at June 30, 2018 12,205 $ 18.27 Vested at June 30, 2018 — —

Variable Interest Entity (Table

Variable Interest Entity (Tables)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entity	The financial position of Mardi Gras at June 30, 2018 and December 31, 2017, its financial performance for the three and six months ended June 30, 2018 and 2017 and cash flows for the six months ended June 30, 2018 and 2017, as reflected in our condensed consolidated financial statements, are as follows: June 30, 2018 December 31, 2017 Balance sheet Equity method investments $ 411,386 $ 422,438 Non-controlling interests 333,487 342,330 Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Statement of operations Income from equity method investments $ 12,153 * $ 24,865 * Less: Net income attributable to non-controlling interests 9,722 * 19,891 * Net impact on Net income attributable to the Partnership $ 2,431 * $ 4,974 * * Information is not applicable as the interest in Mardi Gras was contributed to the Partnership on October 30, 2017. Six Months Ended June 30, 2018 2017 Statement of cash flows Cash flows from operating activities Distributions of earnings received from equity method investments $ 24,865 * Cash flows from investing activities Distribution in excess of earnings from equity method investments 11,053 * Cash flows from financing activities Distributions to non-controlling interests (28,734 ) * Net change on BPMP's cash and cash equivalents $ 7,184 * * Information is not applicable as the interest in Mardi Gras was contributed to the Partnership on October 30, 2017.

Business and Basis of Present28

Business and Basis of Presentation (Details)	6 Months Ended
	Jun. 30, 2018segment	Oct. 30, 2017shares
Variable Interest Entity [Line Items]
Units issued (in shares)		47,794,358
Units issued under over-allotment option (in shares)		5,294,358
Number of reportable segments | segment	1
Mars
Variable Interest Entity [Line Items]
Subsidiary of limited partnership, ownership interest	28.50%
Total Mardi Gras Joint Ventures
Variable Interest Entity [Line Items]
Subsidiary of limited partnership, ownership interest	20.00%
Caesar
Variable Interest Entity [Line Items]
Subsidiary of limited partnership, ownership interest	56.00%
Cleopatra
Variable Interest Entity [Line Items]
Subsidiary of limited partnership, ownership interest	53.00%
Proteus
Variable Interest Entity [Line Items]
Subsidiary of limited partnership, ownership interest	65.00%
Endymion
Variable Interest Entity [Line Items]
Subsidiary of limited partnership, ownership interest	65.00%

Equity Method Investments - Sch

Equity Method Investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Statement of operations data
Revenues	$ 84,218	$ 176,793
Operating expenses	33,758	69,646
Net income	50,573	107,377
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	476,485	487,999
Cumulative effect of accounting change		(2,746)
Distributions	(27,253)	(58,860)
Income from equity method investments	20,842	43,681
Ending Balance	470,074	470,074
Mars
Statement of operations data
Revenues	51,867	109,042
Operating expenses	21,381	43,029
Net income	30,489	66,023
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	60,117	65,561
Cumulative effect of accounting change		(2,746)
Distributions	(10,118)	(22,943)
Income from equity method investments	8,689	18,816
Ending Balance	58,688	58,688
Caesar
Statement of operations data
Revenues	9,832	21,435
Operating expenses	3,548	7,427
Net income	6,284	14,008
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	121,795	123,586
Cumulative effect of accounting change		0
Distributions	(4,480)	(10,597)
Income from equity method investments	3,519	7,845
Ending Balance	120,834	120,834
Cleopatra
Statement of operations data
Revenues	5,222	10,983
Operating expenses	2,419	4,691
Net income	2,803	6,292
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	122,446	123,512
Cumulative effect of accounting change		0
Distributions	(2,385)	(5,300)
Income from equity method investments	1,486	3,335
Ending Balance	121,547	121,547
Proteus
Statement of operations data
Revenues	8,305	16,905
Operating expenses	2,924	6,271
Net income	5,381	10,634
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	85,553	87,144
Cumulative effect of accounting change		0
Distributions	(5,070)	(10,075)
Income from equity method investments	3,498	6,912
Ending Balance	83,981	83,981
Endymion
Statement of operations data
Revenues	8,992	18,428
Operating expenses	3,486	8,228
Net income	5,616	10,420
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	86,574	88,196
Cumulative effect of accounting change		0
Distributions	(5,200)	(9,945)
Income from equity method investments	3,650	6,773
Ending Balance	85,024	85,024
Total Mardi Gras Joint Ventures
Statement of operations data
Revenues	32,351	67,751
Operating expenses	12,377	26,617
Net income	20,084	41,354
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Beginning Balance	416,368	422,438
Cumulative effect of accounting change		0
Distributions	(17,135)	(35,917)
Income from equity method investments	12,153	24,865
Ending Balance	$ 411,386	$ 411,386

Property, Plant and Equipment30

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 106,872	$ 106,226
Less: Accumulated depreciation	(38,057)	(36,738)
Property, plant and equipment, net	68,815	69,488
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	155	155
Rights-of-way
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,380	1,380
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,032	12,032
Pipeline and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	92,208	92,083
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	510	509
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 587	$ 67

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Current portion of environmental remediation obligations	$ 839	$ 1,655
Other accrued liabilities	2,300	2,826
Accrued liabilities	3,139	4,481
Accrued interest - related parties	$ 155	$ 159

Debt (Details)

Debt (Details) - Revolving Credit Facility - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	May 04, 2018	Dec. 31, 2017	Oct. 30, 2017
Line of Credit Facility [Line Items]
Weighted average interest rate	0.00%
Predecessor
Line of Credit Facility [Line Items]
Interest expense				$ 0
Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity							$ 600,000,000
Outstanding borrowing	$ 0		$ 0		$ 15,000,000	$ 15,000,000
Interest expense	$ 200,000		$ 400,000
Weighted average interest rate	2.20%
Commitment fee percentage			0.10%
Utilization fee percentage			0.20%
Line of Credit | Predecessor
Line of Credit Facility [Line Items]
Interest expense		$ 0

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Revenue from related parties	$ 28,169,000		$ 53,990,000
Total Mardi Gras Joint Ventures
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage by Parent	80.00%		80.00%
BP Products
Related Party Transaction [Line Items]
Revenue from related parties	$ 0		$ 0
Related party deferred revenue	$ 2,186,000		2,186,000		$ 0
BP Pipelines
Related Party Transaction [Line Items]
Annual fee paid to related party			$ 13,300,000
Predecessor
Related Party Transaction [Line Items]
Revenue from related parties		$ 26,319,000		$ 52,054,000
Share-based compensation		61,000		104,000
Predecessor | BP Products
Related Party Transaction [Line Items]
Revenue from related parties		$ 0		$ 0

Related Party Transactions - Sc

Related Party Transactions - Schedule of Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Related Party Transaction [Line Items]
Operating expenses—related parties	$ 1,026		$ 1,988
Maintenance expenses—related parties	24		44
General and administrative—related parties	3,442		6,865
Total costs and expenses—related parties	$ 4,492		$ 8,897
Predecessor
Related Party Transaction [Line Items]
Operating expenses—related parties		$ 1,875		$ 3,867
Maintenance expenses—related parties		192		192
General and administrative—related parties		982		2,361
Total costs and expenses—related parties		$ 3,049		$ 6,420

Net Income Per Limited Partne35

Net Income Per Limited Partner Unit - Narrative (Details) - $ / shares	Jul. 18, 2018	May 15, 2018	Feb. 15, 2018	Jun. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dividends paid per share (in dollars per share)		$ 0.2675	$ 0.1798
Subsequent Event
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dividends declared per share (in dollars per share)	$ 0.2725
Predecessor
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Units outstanding (in shares)				0

Net Income Per Limited Partne36

Net Income Per Limited Partner Unit - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income attributable to the Partnership	$ 30,470	$ 61,009
Partner distributions declared	28,544	56,564
Net income attributable to the Partnership in excess of distributions	1,926	4,445
Net Income Subsequent To IPO	$ 30,470	$ 61,009
Weighted average units outstanding:
Basic (in shares)	104,752	104,752
Diluted (in shares)	104,758	104,758
Incentive distribution rights currently held by the General Partner
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	$ 0	$ 0
Net income attributable to the Partnership in excess of distributions	0	0
Net Income Subsequent To IPO	0	0
Limited partners' distribution declared on common units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	14,272	28,282
Net income attributable to the Partnership in excess of distributions	963	2,223
Net Income Subsequent To IPO	$ 15,235	$ 30,505
Weighted average units outstanding:
Basic (in shares)	52,376	52,376
Diluted (in shares)	52,382	52,382
Net income per limited partner unit (in dollars):
Basic (in dollars per share)	$ 0.29	$ 0.58
Diluted (in dollars per share)	$ 0.29	$ 0.58
Limited partners' distribution declared on subordinated units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	$ 14,272	$ 28,282
Net income attributable to the Partnership in excess of distributions	963	2,222
Net Income Subsequent To IPO	$ 15,235	$ 30,504
Weighted average units outstanding:
Basic (in shares)	52,376	52,376
Diluted (in shares)	52,376	52,376
Net income per limited partner unit (in dollars):
Basic (in dollars per share)	$ 0.29	$ 0.58
Diluted (in dollars per share)	$ 0.29	$ 0.58

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenues, fixed loss allowance	$ 2,860		$ 5,000
Predecessor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenues, fixed loss allowance		$ 2,061		$ 3,997
Loss due to change in fair value of fixed loss allowance		$ 312		$ 488

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Contingency [Line Items]
Income tax expense	$ 0		$ 0
Predecessor
Income Tax Contingency [Line Items]
Income tax expense		$ 7,933		$ 15,816

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Site Contingency [Line Items]
Environmental liability indemnification cap	$ 25,000,000
Other matters indemnification cap	15,000,000
Aggregate deductible	500,000
Accrual for environmental loss contingencies	4,102,000	$ 4,438,000
Indemnification asset for environmental loss contingencies	$ 4,102,000	$ 4,438,000
Mars
Site Contingency [Line Items]
Subsidiary of limited partnership, ownership interest	28.50%
Total Mardi Gras Joint Ventures
Site Contingency [Line Items]
Subsidiary of limited partnership, ownership interest	20.00%
Caesar
Site Contingency [Line Items]
Subsidiary of limited partnership, ownership interest	56.00%
Cleopatra
Site Contingency [Line Items]
Subsidiary of limited partnership, ownership interest	53.00%
Endymion
Site Contingency [Line Items]
Subsidiary of limited partnership, ownership interest	65.00%
Proteus
Site Contingency [Line Items]
Subsidiary of limited partnership, ownership interest	65.00%

Unit-Based Compensation - Narra

Unit-Based Compensation - Narrative (Details) - Phantom Share Units (PSUs) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 45	$ 84
Unrecognized compensation cost related to phantom unit awards	$ 120	$ 120
Weighted average recognition period		5 months 24 days
Forfeited (in shares)		0
BP Midstream Partners LP 2017 Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum aggregate number of common units that may be issued (in shares)			5,502,271

Unit-Based Compensation - Phant

Unit-Based Compensation - Phantom Units Activity (Details) - Phantom Share Units (PSUs)	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Number of Units (in units)
Beginning balance outstanding (shares) | shares	8,468
Granted (in shares) | shares	3,737
Ending balance outstanding (shares) | shares	12,205
Vested (in shares) | shares	0
Weighted Average Grant Date Fair Value per Unit (in dollars)
Beginning balance outstanding (in dollars per share) | $ / shares	$ 17.48
Granted (in dollars per share) | $ / shares	20.07
Ending balance outstanding (in dollars per share) | $ / shares	18.27
Vested (in dollars per share) | $ / shares	$ 0

Variable Interest Entity - Sche

Variable Interest Entity - Schedule of Variable Interest Entity (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Balance sheet
Equity method investments	$ 470,074	$ 470,074	$ 476,485	$ 487,999
Non-controlling interests	333,487	333,487		342,330
Statement of operations
Income from equity method investments	20,842	43,681
Less: Net income attributable to non-controlling interests	9,722	19,891
Net impact on Net income attributable to the Partnership	30,470	61,009
Cash flows from operating activities
Distributions of earnings received from equity method investments		47,807
Cash flows from financing activities
Distributions to non-controlling interests		(28,734)
Net change in cash and cash equivalents		7,833
Mardi Gras Transportation System Company LLC | Variable Interest Entity, Primary Beneficiary
Balance sheet
Equity method investments	411,386	411,386		422,438
Non-controlling interests	333,487	333,487		$ 342,330
Statement of operations
Income from equity method investments	12,153	24,865
Less: Net income attributable to non-controlling interests	9,722	19,891
Net impact on Net income attributable to the Partnership	$ 2,431	4,974
Cash flows from operating activities
Distributions of earnings received from equity method investments		24,865
Cash flows from investing activities
Distribution in excess of earnings from equity method investments		11,053
Cash flows from financing activities
Distributions to non-controlling interests		(28,734)
Net change in cash and cash equivalents		$ 7,184

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 15, 2018	Jul. 18, 2018
Scenario, Forecast
Subsequent Event [Line Items]
Total distribution paid	$ 28.5
Dividends paid to non-affiliated common unitholders	13
Net transfers to Parent	$ 15.5
Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share (in dollars per share)		$ 0.2725