BP Midstream Partners (BPMP) 10-Q 5 Aug 21 2021 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 04, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-38260
Entity Registrant Name	BP Midstream Partners LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1646447
Entity Address, Address Line One	501 Westlake Park Boulevard
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77079
City Area Code	281
Local Phone Number	366-2000
Title of 12(b) Security	Common Units, Representing Limited Partner Interests
Trading Symbol	BPMP
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001708301
Common Units
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		104,794,540

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 137,300	$ 126,900
Accounts receivable – third parties	0	200
Accounts receivable – related parties	10,000	11,000
Prepaid expenses	2,400	6,600
Other current assets	2,900	2,900
Total current assets	152,600	147,600
Equity method investments (Note 3)	515,700	519,900
Property, plant and equipment, net (Note 4)	74,800	67,900
Other assets	3,500	3,500
Total assets	746,600	738,900
Current liabilities
Accounts payable – third parties	2,700	1,900
Accounts payable – related parties	2,000	1,900
Deferred revenues and credits – related parties	2,300	1,800
Other current liabilities (Note 5)	8,200	7,800
Total current liabilities	15,200	13,400
Long-term debt – related parties (Note 6)	468,000	468,000
Other liabilities	3,500	3,500
Total liabilities	486,700	484,900
Commitments and contingencies (Note 10)
EQUITY
General partner	1,200	1,200
Total partner's capital	128,900	121,500
Non-controlling interests	131,000	132,500
Total equity	259,900	254,000
Total liabilities and equity	746,600	738,900
Common Units | Public
EQUITY
Common stock	127,700	800,500
Subordinated Units | BP Holdco
EQUITY
Common stock	$ 0	$ (680,200)

CONSOLIDATED BALANCE SHEEETS (P

CONSOLIDATED BALANCE SHEEETS (Parenthetical) - shares	Jun. 30, 2021	Dec. 31, 2020
Public | Common Units
Units outstanding (in shares)	47,837,828	47,806,563
Units issued (in shares)	47,837,828	47,806,563
BP Holdco | Common Units
Units outstanding (in shares)	56,956,712	4,581,177
Units issued (in shares)	56,956,712	4,581,177
BP Holdco | Subordinated Units
Units outstanding (in shares)	0	52,375,535
Units issued (in shares)	0	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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue
Third parties	$ 800	$ 800	$ 1,600	$ 1,800
Related parties	28,500	30,700	57,300	60,400
Total revenue	29,300	31,500	58,900	62,200
Costs and expenses
Operating expenses – third parties	3,800	3,100	7,300	6,800
Operating expenses – related parties	1,400	1,300	2,600	2,800
Maintenance expenses – related parties	100	100	100	200
General and administrative – third parties	600	700	1,200	1,600
General and administrative – related parties	3,900	3,600	7,900	7,500
Depreciation	600	600	1,300	1,300
Property and other taxes	200	200	400	300
Total costs and expenses	10,900	11,000	21,900	22,100
Operating income	18,400	20,500	37,000	40,100
Income from equity method investments	28,600	26,800	58,900	58,100
Interest expense, net	1,100	1,900	2,200	5,300
Net income	45,900	45,400	93,700	92,900
Less: Net income attributable to non-controlling interests	5,400	4,800	11,200	10,600
Net income attributable to the Partnership	40,500	40,600	82,500	82,300
Limited Partners Common Units
Costs and expenses
Net income attributable to the Partnership	$ 39,300	$ 19,700	$ 70,600	$ 40,000
Net income attributable to the Partnership per limited partner unit – basic and diluted (in dollars):
Net income attributable to the Partnership per limited partner unit – basic and diluted (in dollars per share)	$ 0.37	$ 0.38	$ 0.76	$ 0.77
Limited Partners Subordinated Units
Costs and expenses
Net income attributable to the Partnership	$ 0	$ 19,700	$ 9,500	$ 39,900
Net income attributable to the Partnership per limited partner unit – basic and diluted (in dollars):
Net income attributable to the Partnership per limited partner unit – basic and diluted (in dollars per share)	$ 0	$ 0.38	$ 0.18	$ 0.77
Common Units Public
Weighted average number of limited partner units outstanding – basic and diluted (in millions):
Weighted average number of limited partner units outstanding - basic and diluted (in shares)	47.8	47.8	47.8	47.8
BP Holdco | Common Units BP Holdco
Weighted average number of limited partner units outstanding – basic and diluted (in millions):
Weighted average number of limited partner units outstanding - basic and diluted (in shares)	57	4.6	44.8	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 - basic and diluted (in shares)	0	52.4	52.4	52.4
Maintenance
Costs and expenses
Maintenance expenses – third parties	$ 300	$ 1,400	$ 1,100	$ 1,600

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Noncontrolling Interest [Member]	Common UnitsMember Units [Member]General Public	Subordinated UnitsMember Units [Member]BP Holdco	General Partner
Beginning Balance at Dec. 31, 2019	$ 240.2	$ 136.9	$ 791.3	$ (689.2)	$ 1.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	92.9
Ending Balance at Jun. 30, 2020				1.2
Beginning Balance at Dec. 31, 2020	254	$ 132.5	$ 800.5	$ (680.2)	$ 1.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	93.7
Ending Balance at Jun. 30, 2021	$ 259.9

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) (Parenthetical) - $ / shares	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Cash distributions per unit paid (in dollars per unit)	$ 0.3475	$ 0.3475	$ 0.3126	$ 0.3015

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net income	$ 93.7	$ 92.9
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation	1.3	1.3
Non-cash expenses	0.1	0.1
Income from equity method investments	(58.9)	(58.1)
Distributions of earnings received from equity method investments	58.8	60.7
Changes in operating assets and liabilities
Accounts receivable	1.1	1
Prepaid expenses and other current assets	4.3	3.1
Accounts payable	1	(0.1)
Deferred revenues and credits – related parties	0.5	0.1
Other	(0.4)	(1.5)
Net cash provided by operating activities	101.5	99.5
Cash flows from investing activities
Capital expenditures	(7.5)	(1.3)
Distributions in excess of earnings from equity method investments	4.3	5.3
Net cash (used in) provided by investing activities	(3.2)	4
Cash flows from financing activities
Proceeds from issuance of debt – related parties	0	(468)
Distributions to unitholders and general partner	(75.2)	(75.2)
Distributions to non-controlling interests	(12.7)	(12.2)
Net cash used in financing activities	(87.9)	(87.4)
Net change in cash and cash equivalents	10.4	16.1
Cash and cash equivalents at beginning of the period	126.9	98.8
Cash and cash equivalents at end of the period	137.3	114.9
Supplemental cash flow information
Cash paid for interest	2.3	8.3
Non-cash investing transactions
Accrued capital expenditures	5.1	0.5
Proceeds from Issuance of Long-term Debt	$ 0	$ 468

Business and Basis of Presentat

Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2021
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. Unless otherwise stated or the context otherwise indicates, all references to “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. Business BP Midstream Partners LP is a master limited partnership formed by BP Pipelines to own, operate, develop and acquire pipelines and other midstream assets. The Partnership's assets consist of interests in entities that own crude oil, natural gas, refined products and diluent pipelines and refined product terminals 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 assets deliver refined products and diluent from the Whiting Refinery and other U.S. supply hubs to major demand centers. As of June 30, 2021, the Partnership's assets consisted 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, together, are referred to as the "Wholly Owned Assets". • 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. • 65% ownership interest and 100% 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: • 56% ownership interest in Caesar Oil Pipeline Company, LLC (“Caesar”), • 53% ownership interest in Cleopatra Gas Gathering Company, LLC (“Cleopatra”), • 65% ownership interest in Proteus Oil Pipeline Company, LLC (“Proteus”), and, • 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.” • 22.7% ownership interest in Ursa Oil Pipeline Company, LLC ("Ursa"). • 25% ownership interest in KM Phoenix Holdings, LLC ("KM Phoenix"). We generate a majority of revenue by charging fees for the transportation of crude oil, refined products and diluent through our pipelines under agreements with minimum volume commitments ("MVC"). We do not engage in the marketing and trading of any commodities. All operations are conducted in the United States, and all long-lived assets are located in the United States. Partnership operations consist of one reportable segment. Certain Partnership businesses 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 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, 2021, and for the three and six months ended June 30, 2021 and 2020, 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 condensed 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 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, 2020 (the "Partnership's 2020 10-K"). Partnership 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. Subordinated Unit Conversion On February 11, 2021, we paid a cash distribution of $0.3475 per limited partner unit to unitholders of record on January 28, 2021, for the three months ended December 31, 2020. Following payment of the distribution, the board of directors of our General Partner confirmed and approved that the financial tests required for conversion of our subordinated units had been met under the terms of the partnership agreement. As a result, on February 12, 2021, all of the Partnership's subordinated units were converted into common units on a one-for-one basis and the subordination period was terminated. Refer to Note 8 - Net Income Per Limited Partner Unit for additional information. As a result of the completion of this conversion event, common units are presented on a combined basis in the condensed consolidated balance sheets and the condensed consolidated statements of changes in equity as of and for the period ended June 30, 2021. Prior periods have been reclassified in the comparative periods to conform to current period presentation in the condensed consolidated balance sheets and the condensed consolidated statements of changes in equity. Summary of Significant Accounting Policies There have been no significant changes to accounting policies as disclosed in Note 2 - Summary of Significant Accounting Policies in the Partnership's 2020 10-K.

Equity Method Investments

Equity Method Investments	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments We account for ownership interests in Mars, the Mardi Gras Joint Ventures, Ursa, and KM Phoenix using the equity method for financial reporting purposes. Financial results include the Partnership's proportionate share of Mars, the Mardi Gras Joint Ventures, Ursa and KM Phoenix, which is reflected in Income from equity method investments on the condensed consolidated statements of operations. We did not record any impairment loss on equity method investments during the three and six months ended June 30, 2021 and 2020. The table below summarizes the balances and activities related for each equity method investment ("EMI") recorded as of and for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, 2021 Three Months Ended June 30, 2020 Percentage Ownership Distributions Received Income from EMI Carrying Value Percentage Ownership Distributions Received Income from EMI Carrying Value Mars 28.5% $ (12.1) $ 10.3 $ 53.1 28.5% $ (13.7) $ 11.6 $ 54.3 Caesar 56.0% (5.3) 4.2 115.3 56.0% (3.4) 3.7 117.3 Cleopatra 53.0% (2.6) 1.9 113.1 53.0% (2.4) 1.2 115.5 Proteus 65.0% (3.4) 3.1 67.4 65.0% (5.2) 3.6 72.3 Endymion 65.0% (6.6) 6.4 78.6 65.0% (4.8) 5.2 81.5 Others (1) Various (2.9) 2.7 88.2 Various (2.3) 1.5 85.6 Total Equity Investments $ (32.9) $ 28.6 $ 515.7 $ (31.8) $ 26.8 $ 526.5 Six Months Ended June 30, 2021 Six Months Ended June 30, 2020 Percentage Ownership Distributions Received Income from EMI Carrying Value Percentage Ownership Distributions Received Income from EMI Carrying Value Mars 28.5% $ (23.1) $ 22.1 $ 53.1 28.5% $ (26.7) $ 24.1 $ 54.3 Caesar 56.0% (9.2) 8.0 115.3 56.0% (8.3) 8.2 117.3 Cleopatra 53.0% (4.2) 3.0 113.1 53.0% (5.3) 3.2 115.5 Proteus 65.0% (8.1) 7.1 67.4 65.0% (10.7) 7.7 72.3 Endymion 65.0% (14.6) 13.9 78.6 65.0% (10.7) 11.2 81.5 Others (1) Various (3.9) 4.8 88.2 Various (4.3) 3.7 85.6 Total Equity Investments $ (63.1) $ 58.9 $ 515.7 $ (66.0) $ 58.1 $ 526.5 (1) Includes ownership in Ursa (22.7%) and KM Phoenix (25%). The following table presents aggregated selected income statement data for equity method investments on a 100% basis for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, 2021 2020 Statement of operations Revenue $ 128.7 $ 127.0 Operating expenses 56.2 57.1 Net income 72.6 70.0

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consisted of the following: June 30, 2021 December 31, 2020 Land $ 0.2 $ 0.2 Rights-of-way assets 1.4 1.4 Buildings and improvements 6.9 6.9 Pipelines and equipment 95.5 95.3 Other 0.9 0.8 Construction in progress 15.0 7.1 Property, plant and equipment 119.9 111.7 Less: Accumulated depreciation (45.1) (43.8) Property, plant and equipment, net $ 74.8 $ 67.9 There were no impairments on property, plant and equipment for the three and six months ended June 30, 2021 and 2020.

Other Current Liabilities

Other Current Liabilities	6 Months Ended
	Jun. 30, 2021
Payables and Accruals [Abstract]
Other Current Liabilities	Other Current Liabilities Other current liabilities consisted of the following: June 30, 2021 December 31, 2020 Accrued capital expenditures $ 5.1 $ 4.1 Accrued interest payable – related parties 0.8 0.9 Current portion of environmental remediation obligation 0.5 0.4 Current portion of lease liabilities 0.1 0.1 Accrued liabilities 1.7 2.3 Other current liabilities $ 8.2 $ 7.8

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	Debt On February 24, 2020, we entered i nto a $468 million Term Loan Facility Agreement ("term loan") with an affiliate of BP. On March 13, 2020, proceeds were used to repay outstanding borrowings under the exist ing credit facility ("credit facility"). Refer to Note 9 - Debt in the Partnership's 2020 10-K for additional information. The term loan has a final repayment date of Februa ry 24, 2025, and provides for certain covenants, including the requirement to maintain a consolidated leverage ratio, which is calculated as total indebtedness to consolidated EBITDA, not to exceed 5.0 to 1.0, subject to a temporary increase in such ratio to 5.5 to 1.0 in connection with certain material acquisitions. Simultaneous with this transaction, we entered into a First Amendment to Short Term Credit Facility Agreement whereby the lender added a provision that indebtedness under both the term loan and the credit facility shall not exceed $600 million. All other terms of the credit facility remain the same. As of June 30, 2021, the Partnership was in compliance with the covenants contained in the term loan facility and the credit facility. There were $468 million of outstanding borrowi ngs under the term loan at June 30, 2021 and December 31, 2020. Interest charges and fees were $1.1 million and $2.2 million for the three and six months ended June 3 0 , 20 21, respectively. Interest charges and fees were $2.0 million and $5.6 million for the three and six months ended June 30, 2020, respectively. Indebtedness under the term loan bears interest at the 3-month LIBOR plus 0.73%. For the three and six months ended June 30, 2021, the weighted average interest rates for our long-term debt were 0.92% an d 0.93% , respectively. For the three and six months ended June 30, 2020, the weighted average interest rates for our long-term debt were 1.69% an d 2.28 % , respectively.

Net Income Per Limited Partner

Net Income Per Limited Partner Unit	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Income Per Limited Partner Unit	Net Income Per Limited Partner Unit The following table details the distributions declared and/or paid for the periods presented: Three Months Ended Date Paid or General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions per Limited Partner Unit (in dollars) December 31, 2019 February 13, 2020 $ 1.2 $ 18.2 $ 18.2 $ 37.6 $ 0.3475 March 31, 2020 May 14, 2020 1.2 18.2 18.2 37.6 0.3475 June 30, 2020 August 13, 2020 1.2 18.2 18.2 37.6 0.3475 December 31, 2020 February 11, 2021 1.2 18.2 18.2 37.6 0.3475 March 31, 2021 May 13, 2021 1.2 36.4 — 37.6 0.3475 June 30, 2021 August 12, 2021 1.2 36.4 — 37.6 0.3475 Earnings in excess of distributions are allocated to the limited partners based on their respective percentage interests. Payments made to the Partnership’s unitholders are determined in relation to actual distributions declared and are not based on the net income allocations used in the calculation of net income per unit. In addition to the common and subordinated units, the Partnership also identified the incentive distribution rights ("IDRs") currently held by the General Partner as a participating security and uses the two-class method when calculating the net income per unit applicable to limited partners that is based on the weighted-average number of common units outstanding during the period. Following the payment of the distribution on February 11, 2021, the financial tests required for the conversion of our subordinated units were satisfied under the terms of our partnership agreement. As a result, on February 12, 2021, all of the Partnership's subordinated units were converted into common units on a one-for-one basis and the subordination period was terminated. Following the conversion, we continue to use the two-class method when calculating the net income per unit applicable to limited partners. The remaining classes of participating securities are common units and IDRs. When calculating basic earnings per unit under the two-class method for a master limited partnership, net income for the current reporting period is reduced by the amount of available cash that will be distributed to the General Partner and limited partners for that reporting period. 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, 2021 and 2020: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Net income attributable to the Partnership $ 40.5 $ 40.6 $ 82.5 $ 82.3 Less: Incentive distribution rights currently held by the General Partner 1.2 1.2 2.4 2.4 Limited partners' distribution declared on common units 36.4 18.2 72.8 36.4 Limited partners' distribution declared on subordinated units — 18.2 — 36.4 Net income attributable to the Partnership in excess of distributions $ 2.9 $ 3.0 $ 7.3 $ 7.1 Three Months Ended June 30, 2021 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ 1.2 $ 36.4 $ — $ 37.6 Net income attributable to the Partnership in excess of distributions — 2.9 — 2.9 Net income attributable to the Partnership $ 1.2 $ 39.3 $ — $ 40.5 Weighted average units outstanding: Basic and Diluted 104.8 — Net income per limited partner unit (in dollars): Basic and Diluted $ 0.37 $ — Six Months Ended June 30, 2021 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ 2.4 $ 72.8 $ — $ 75.2 Net income attributable to the Partnership in excess of distributions — (2.2) 9.5 7.3 Net income attributable to the Partnership $ 2.4 $ 70.6 $ 9.5 $ 82.5 Weighted average units outstanding: Basic and Diluted (1) 92.6 52.4 Net income per limited partner unit (in dollars): Basic and Diluted (1) $ 0.76 $ 0.18 (1) The 52.4 million weighted average subordinated units outstanding and $0.18 net income per limited partner unit have been calculated only for the period prior to conversion. All of the subordinated units were converted into common units on February 12, 2021. On April 15, 2021, the Partnership declared a cash distribution of $0.3475 per limited partner unit to unitholders of record on April 29, 2021, for the three months ended March 31, 2021. All of the subordinated units were converted into common units on February 12, 2021. As a result, on the date of record, there were no subordinated units outstanding, and therefore, no portion of the cash distribution was allocated to the limited partners' subordinated units. However, pursuant to the requirements of the two-class method, and as stated above, the net income per unit amount applicable to the subordinated units has been calculated for the period of time the units were outstanding prior to their conversion. Three Months Ended June 30, 2020 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ 1.2 $ 18.2 $ 18.2 $ 37.6 Net income attributable to the Partnership in excess of distributions — 1.5 1.5 3.0 Net income attributable to the Partnership $ 1.2 $ 19.7 $ 19.7 $ 40.6 Weighted average units outstanding: Basic and Diluted 52.4 52.4 Net income per limited partner unit (in dollars): Basic and Diluted $ 0.38 $ 0.38

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The carrying amounts of accounts receivable, other current assets, accounts payable, and other current liabilities approximate their fair values due to their short-term nature. The carrying value of borrowings under the term loan as of June 30, 2021 and December 31, 2020 approximate fair value as the interest rates are reflective of market rates.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings The Partnership is a party to ongoing legal proceedings in the ordinary course of business. For each outstanding legal matter, if any, we will evaluate the merits of the case, 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 the Partnership's 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 our ownership. 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 65% 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 considered. Indemnification for certain identified environmental liabilities is subject to a cap of $25 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 was limited to liabilities due to occurrences on or before October 30, 2017, which were identified prior to October 30, 2020. We continue to maintain indemnification by our General Partner for matters previously discovered. To the extent that unknown environmental liabilities arise relating to prior ownership, the Partnership will be liable. The Interest Purchase Agreement contains customary representations, warranties and covenants of our Parent and the Partnership. Our Parent, on the one hand, and the Partnership, on the other hand, have agreed to indemnify each other and their respective affiliates, officers, directors and other representatives against certain losses, including those resulting from any breach of their representations, warranties or covenants contained in the Interest Purchase Agreement, subject to certain limitations and survival periods. This agreement covers the Partnership’s ownership of 22.7% in Ursa and 25% in KM Phoenix. 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 progress, 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 Partnership ownership. Revisions to the estimated environmental liability for conditions that are not indemnified under the omnibus agreement with our Parent are reflected in the Partnership's condensed consolidated statements of operations in the year in which they are probable and reasonably estimable. We accru ed $3.5 million and $3.4 million for environmental liabilities at June 30, 2021 and December 31, 2020, respectively. These balances are broken down on the condensed consolidated balance sheets as follows: Balance sheet location June 30, 2021 December 31, 2020 Current portion of environmental remediation obligations Other current liabilities $ 0.5 $ 0.4 Long-term portion of environmental remediation obligations Other liabilities 3.0 3.0 Total $ 3.5 $ 3.4 The balances are related to incidents that occurre d prior to our ownership and are entirely indemnified by our Parent. As a result, we recorded corresponding indemnification assets $3.5 million and $3.4 million at June 30, 2021 and December 31, 2020, respectively. These balances are broken down on the condensed consolidated balance sheets as follows: Balance sheet location June 30, 2021 December 31, 2020 Current portion of indemnification assets Other current assets $ 0.5 $ 0.4 Non-current portion of indemnification assets Other assets 3.0 3.0 Total $ 3.5 $ 3.4 Griffith Station Incident

Unit-Based Compensation

Unit-Based Compensation	3 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Unit-Based Compensation	11. Unit-Based Compensation Long-Term Incentive Plan On October 26, 2017, the General Partner 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, 2021: Phantom Units Number of Units (in units) Weighted Average Grant Date Fair Value per Unit (in dollars) Outstanding at December 31, 2020 16,038 $ 14.03 Granted 18,534 12.00 Vested (16,038) 14.03 Outstanding at June 30, 2021 18,534 $ 12.00 For the three and six months ended June 30, 2021, total compensation expense recognized for phantom unit awards were approximately $56 thousand and $111 thousand, respectively. For the three and six months ended June 30, 2020, total compensation expense recognized for phantom unit awards was approximately $56 thousand and $119 thousand, respectively. The unrecognized compensation cost related to phantom unit awards was approximately $146 thousand at June 30, 2021, which is expected to be recognized over a weighted average period of 0.7

Variable Interest Entity

Variable Interest Entity	3 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entity	12. Variable Interest Entity Mardi Gras is a Delaware limited liability company and a pass-through entity for U.S. federal and state income tax purposes. 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. The remaining interests in each of the Mardi Gras Joint Ventures are owned by unaffiliated third-party investors. Each of the Mardi Gras Joint Ventures is managed by its respective management committee, and decisions made by these management committees require approval of two or more members that are not affiliates with equity interest holdings meeting certain thresholds. We have 65% ownership interest and 100% managing member interest in Mardi Gras. The remainder of the economic interest in Mardi Gras was held 34% by BP Pipelines and 1% by an affiliate of BP. Through our managing member interest in Mardi Gras, we have the right to vote 100% of Mardi Gras’ interest in each of the Mardi Gras Joint Ventures. We determined that Mardi Gras is a variable interest entity because (i) we hold disproportional voting rights as compared to our economic interest in Mardi Gras, and (ii) substantially all of Mardi Gras’ activities involve or are conducted on behalf of our Parent, which holds disproportionately few voting rights. The managing member interest in Mardi Gras provides us with the unilateral power to direct the activities of Mardi Gras that most significantly impact its economic performance including the right to exercise the voting rights of BP for each of the Mardi Gras Joint Ventures. In addition, our obligations to absorb the expected losses of and the right to receive the residual returns from Mardi Gras relative to our economic ownership is significant to Mardi Gras. As a result, we are the primary beneficiary of Mardi Gras and consolidate Mardi Gras. We have the obligation to provide financial support to Mardi Gras if all members unanimously determine that additional capital contributions are necessary to fund Mardi Gras’ operations. The assets of Mardi Gras can only be used to satisfy its own obligations, which were zero at June 30, 2021 and December 31, 2020. Under the current limited liability company agreement of Mardi Gras, creditors of Mardi Gras, if any, do not have any recourse to the general credit of the Partnership. The financial position of Mardi Gras at June 30, 2021 and December 31, 2020, its financial performance for the three and six months ended June 30, 2021 and 2020 and cash flows for the six months ended June 30, 2021 and 2020, as reflected in the condensed consolidated financial statements, are as follows: June 30, 2021 December 31, 2020 Balance sheet Equity method investments $ 374.4 $ 378.5 Non-controlling interests 131.0 132.5 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Statement of operations Income from equity method investments $ 15.6 $ 13.7 $ 32.0 $ 30.3 Less: Net income attributable to non-controlling interests 5.4 4.8 11.2 10.6 Net impact on Net income attributable to the Partnership $ 10.2 $ 8.9 $ 20.8 $ 19.7 Six Months Ended June 30, 2021 2020 Statement of cash flows Cash flows from operating activities Distributions of earnings received from equity method investments $ 31.9 $ 29.8 Cash flows from investing activities Distribution in excess of earnings from equity method investments 4.2 5.2 Cash flows from financing activities Distributions to non-controlling interests (12.7) (12.2) Net change on the Partnership's cash and cash equivalents $ 23.4 $ 22.8

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2021
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 items noted below, that require recognition or disclosure in the condensed consolidated financial statements. Distribution

Business and Basis of Present_2

Business and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation 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, 2021, and for the three and six months ended June 30, 2021 and 2020, 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 condensed 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 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, 2020 (the "Partnership's 2020 10-K"). Partnership 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.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Transportation services revenue – third parties $ 0.8 $ 0.8 $ 1.6 $ 1.8 Transportation services revenue – related parties 28.5 30.7 57.3 60.4 Total revenue $ 29.3 $ 31.5 $ 58.9 $ 62.2
Summary of Remaining Performance Obligation, Expected Timing of Satisfaction	As of June 30, 2021 Remainder of 2021 $ 55.2 2022 102.0 2023 98.2 Total $ 255.4 As of June 30, 2021 we have executed a Capital Recovery Fee Agreement with BP Products and commenced construction of an onshore capacity increase project. The agreement calls for fees of $6.0 million per year (payable in equal monthly installments) over a four-year period, beginning when the increased capacity becomes available for use.
Summary of Contract with Customer, Assets and Liabilities	The following table provides information about receivables from contracts with customers, contract assets and contract liabilities: June 30, 2021 December 31, 2020 Receivables from contracts with customers – third parties $ — $ 0.2 Receivables from contracts with customers – related parties 10.0 11.0 Deferred revenues and credits – related parties 2.3 1.8

Equity Method Investments (Tabl

Equity Method Investments (Tables)	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Equity Method Investments	Three Months Ended June 30, 2021 Three Months Ended June 30, 2020 Percentage Ownership Distributions Received Income from EMI Carrying Value Percentage Ownership Distributions Received Income from EMI Carrying Value Mars 28.5% $ (12.1) $ 10.3 $ 53.1 28.5% $ (13.7) $ 11.6 $ 54.3 Caesar 56.0% (5.3) 4.2 115.3 56.0% (3.4) 3.7 117.3 Cleopatra 53.0% (2.6) 1.9 113.1 53.0% (2.4) 1.2 115.5 Proteus 65.0% (3.4) 3.1 67.4 65.0% (5.2) 3.6 72.3 Endymion 65.0% (6.6) 6.4 78.6 65.0% (4.8) 5.2 81.5 Others (1) Various (2.9) 2.7 88.2 Various (2.3) 1.5 85.6 Total Equity Investments $ (32.9) $ 28.6 $ 515.7 $ (31.8) $ 26.8 $ 526.5 Six Months Ended June 30, 2021 Six Months Ended June 30, 2020 Percentage Ownership Distributions Received Income from EMI Carrying Value Percentage Ownership Distributions Received Income from EMI Carrying Value Mars 28.5% $ (23.1) $ 22.1 $ 53.1 28.5% $ (26.7) $ 24.1 $ 54.3 Caesar 56.0% (9.2) 8.0 115.3 56.0% (8.3) 8.2 117.3 Cleopatra 53.0% (4.2) 3.0 113.1 53.0% (5.3) 3.2 115.5 Proteus 65.0% (8.1) 7.1 67.4 65.0% (10.7) 7.7 72.3 Endymion 65.0% (14.6) 13.9 78.6 65.0% (10.7) 11.2 81.5 Others (1) Various (3.9) 4.8 88.2 Various (4.3) 3.7 85.6 Total Equity Investments $ (63.1) $ 58.9 $ 515.7 $ (66.0) $ 58.1 $ 526.5 (1) Includes ownership in Ursa (22.7%) and KM Phoenix (25%). The following table presents aggregated selected income statement data for equity method investments on a 100% basis for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, 2021 2020 Statement of operations Revenue $ 128.7 $ 127.0 Operating expenses 56.2 57.1 Net income 72.6 70.0

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Components of Property, Plant and Equipment	Property, plant and equipment consisted of the following: June 30, 2021 December 31, 2020 Land $ 0.2 $ 0.2 Rights-of-way assets 1.4 1.4 Buildings and improvements 6.9 6.9 Pipelines and equipment 95.5 95.3 Other 0.9 0.8 Construction in progress 15.0 7.1 Property, plant and equipment 119.9 111.7 Less: Accumulated depreciation (45.1) (43.8) Property, plant and equipment, net $ 74.8 $ 67.9

Other Current Liabilities (Tabl

Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2021
Payables and Accruals [Abstract]
Schedule of Other Current Liabilities	Other current liabilities consisted of the following: June 30, 2021 December 31, 2020 Accrued capital expenditures $ 5.1 $ 4.1 Accrued interest payable – related parties 0.8 0.9 Current portion of environmental remediation obligation 0.5 0.4 Current portion of lease liabilities 0.1 0.1 Accrued liabilities 1.7 2.3 Other current liabilities $ 8.2 $ 7.8

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating expenses—related parties $ 1.4 $ 1.3 $ 2.6 $ 2.8 Maintenance expenses—related parties 0.1 0.1 0.1 0.2 General and administrative—related parties 3.9 3.6 7.9 7.5 Total costs and expenses—related parties $ 5.4 $ 5.0 $ 10.6 $ 10.5

Net Income Per Limited Partne_2

Net Income Per Limited Partner Unit (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule of Distributions	The following table details the distributions declared and/or paid for the periods presented: Three Months Ended Date Paid or General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions per Limited Partner Unit (in dollars) December 31, 2019 February 13, 2020 $ 1.2 $ 18.2 $ 18.2 $ 37.6 $ 0.3475 March 31, 2020 May 14, 2020 1.2 18.2 18.2 37.6 0.3475 June 30, 2020 August 13, 2020 1.2 18.2 18.2 37.6 0.3475 December 31, 2020 February 11, 2021 1.2 18.2 18.2 37.6 0.3475 March 31, 2021 May 13, 2021 1.2 36.4 — 37.6 0.3475 June 30, 2021 August 12, 2021 1.2 36.4 — 37.6 0.3475
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, 2021 and 2020: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Net income attributable to the Partnership $ 40.5 $ 40.6 $ 82.5 $ 82.3 Less: Incentive distribution rights currently held by the General Partner 1.2 1.2 2.4 2.4 Limited partners' distribution declared on common units 36.4 18.2 72.8 36.4 Limited partners' distribution declared on subordinated units — 18.2 — 36.4 Net income attributable to the Partnership in excess of distributions $ 2.9 $ 3.0 $ 7.3 $ 7.1 Three Months Ended June 30, 2021 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ 1.2 $ 36.4 $ — $ 37.6 Net income attributable to the Partnership in excess of distributions — 2.9 — 2.9 Net income attributable to the Partnership $ 1.2 $ 39.3 $ — $ 40.5 Weighted average units outstanding: Basic and Diluted 104.8 — Net income per limited partner unit (in dollars): Basic and Diluted $ 0.37 $ — Six Months Ended June 30, 2021 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ 2.4 $ 72.8 $ — $ 75.2 Net income attributable to the Partnership in excess of distributions — (2.2) 9.5 7.3 Net income attributable to the Partnership $ 2.4 $ 70.6 $ 9.5 $ 82.5 Weighted average units outstanding: Basic and Diluted (1) 92.6 52.4 Net income per limited partner unit (in dollars): Basic and Diluted (1) $ 0.76 $ 0.18 (1) The 52.4 million weighted average subordinated units outstanding and $0.18 net income per limited partner unit have been calculated only for the period prior to conversion. All of the subordinated units were converted into common units on February 12, 2021. On April 15, 2021, the Partnership declared a cash distribution of $0.3475 per limited partner unit to unitholders of record on April 29, 2021, for the three months ended March 31, 2021. All of the subordinated units were converted into common units on February 12, 2021. As a result, on the date of record, there were no subordinated units outstanding, and therefore, no portion of the cash distribution was allocated to the limited partners' subordinated units. However, pursuant to the requirements of the two-class method, and as stated above, the net income per unit amount applicable to the subordinated units has been calculated for the period of time the units were outstanding prior to their conversion. Three Months Ended June 30, 2020 General Partner Limited Partners' Common Units Limited Partners' Subordinated Units Total Distributions declared $ 1.2 $ 18.2 $ 18.2 $ 37.6 Net income attributable to the Partnership in excess of distributions — 1.5 1.5 3.0 Net income attributable to the Partnership $ 1.2 $ 19.7 $ 19.7 $ 40.6 Weighted average units outstanding: Basic and Diluted 52.4 52.4 Net income per limited partner unit (in dollars): Basic and Diluted $ 0.38 $ 0.38

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of Balance Sheet Classification of Environmental Liabilities	These balances are broken down on the condensed consolidated balance sheets as follows: Balance sheet location June 30, 2021 December 31, 2020 Current portion of environmental remediation obligations Other current liabilities $ 0.5 $ 0.4 Long-term portion of environmental remediation obligations Other liabilities 3.0 3.0 Total $ 3.5 $ 3.4
Schedule Of Indemnification Asset For Environmental Loss Contingencies	These balances are broken down on the condensed consolidated balance sheets as follows: Balance sheet location June 30, 2021 December 31, 2020 Current portion of indemnification assets Other current assets $ 0.5 $ 0.4 Non-current portion of indemnification assets Other assets 3.0 3.0 Total $ 3.5 $ 3.4

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [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, 2021: Phantom Units Number of Units (in units) Weighted Average Grant Date Fair Value per Unit (in dollars) Outstanding at December 31, 2020 16,038 $ 14.03 Granted 18,534 12.00 Vested (16,038) 14.03 Outstanding at June 30, 2021 18,534 $ 12.00

Variable Interest Entity (Table

Variable Interest Entity (Tables)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entity	The financial position of Mardi Gras at June 30, 2021 and December 31, 2020, its financial performance for the three and six months ended June 30, 2021 and 2020 and cash flows for the six months ended June 30, 2021 and 2020, as reflected in the condensed consolidated financial statements, are as follows: June 30, 2021 December 31, 2020 Balance sheet Equity method investments $ 374.4 $ 378.5 Non-controlling interests 131.0 132.5 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Statement of operations Income from equity method investments $ 15.6 $ 13.7 $ 32.0 $ 30.3 Less: Net income attributable to non-controlling interests 5.4 4.8 11.2 10.6 Net impact on Net income attributable to the Partnership $ 10.2 $ 8.9 $ 20.8 $ 19.7 Six Months Ended June 30, 2021 2020 Statement of cash flows Cash flows from operating activities Distributions of earnings received from equity method investments $ 31.9 $ 29.8 Cash flows from investing activities Distribution in excess of earnings from equity method investments 4.2 5.2 Cash flows from financing activities Distributions to non-controlling interests (12.7) (12.2) Net change on the Partnership's cash and cash equivalents $ 23.4 $ 22.8

Business and Basis of Present_3

Business and Basis of Presentation (Details) - segment	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Variable Interest Entity [Line Items]
Number of reportable segments	1
KM Phoenix
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	25.00%
Total Mardi Gras Joint Ventures
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	65.00%
KM Phoenix
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	25.00%
Ursa
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	22.70%
Mars
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	28.50%	28500000.00%
Caesar
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	56.00%	56000000.00%
Cleopatra
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	53.00%	53000000.00%
Proteus
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	65.00%	65000000.00%
Endymion
Variable Interest Entity [Line Items]
Equity Method Investment, Ownership Percentage	65.00%	65000000.00%

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Income related to FLA arrangements with Parent	$ 3,000,000	$ 800,000	$ 5,600,000	$ 2,300,000
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Income related to FLA arrangements with Parent	3,000,000	800,000	5,600,000	2,300,000
Related parties	28,500,000	30,700,000	57,300,000	60,400,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Income related to FLA arrangements with Parent	3,000,000	800,000	5,600,000	2,300,000
Disaggregation of Revenue [Line Items]
Income related to FLA arrangements with Parent	$ 3,000,000	$ 800,000	$ 5,600,000	$ 2,300,000
Weighted average interest rate				2.28%

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Transportation services revenue – third parties	$ 0.8	$ 0.8	$ 1.6	$ 1.8
Transportation services revenue – related parties	28.5	30.7	57.3	60.4
Total revenue	$ 29.3	$ 31.5	$ 58.9	$ 62.2

Revenue Recognition - Remaining

Revenue Recognition - Remaining Performance Obligation, Expected Timing of Satisfaction (Details) $ in Millions	Jun. 30, 2021USD ($)
Revenue from Contract with Customer [Abstract]
Unfulfilled performance obligations	$ 255.4
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, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue from Contract with Customer [Abstract]
Unfulfilled performance obligations	$ 55.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Unfulfilled performance obligations	102
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Unfulfilled performance obligations	$ 98.2

Revenue Recognition - Contract

Revenue Recognition - Contract with Customer, Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from contracts with customers	$ 0	$ 0.2
Third parties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from contracts with customers	0	0.2
Related parties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables from contracts with customers	10	11
Deferred revenue and credits	$ 2.3	$ 1.8

Equity Method Investments - Nar

Equity Method Investments - Narrative (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Impairment loss on equity method investments	$ 0	$ 0

Equity Method Investments - Sch

Equity Method Investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	$ 32,900	$ 31,800	$ 63,100	$ 66,000
Income from equity method investments	28,600	26,800	58,900	58,100
Equity method investments	515,700	526,500	515,700	526,500	$ 519,900
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	128,700	127,000	262,700	271,600
Operating expenses	56,200	57,100	113,600	121,400
Net income	$ 72,600	$ 70,000	$ 149,200	$ 150,500
Mars
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	28.50%	28500000.00%	28.50%	28500000.00%
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	$ 12,100	$ 13,700	$ 23,100	$ 26,700
Income from equity method investments	10,300	11,600	22,100	24,100
Equity method investments	$ 53,100	$ 54,300	$ 53,100	$ 54,300
Caesar
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	56.00%	56000000.00%	56.00%	56000000.00%
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	$ 5,300	$ 3,400	$ 9,200	$ 8,300
Income from equity method investments	4,200	3,700	8,000	8,200
Equity method investments	$ 115,300	$ 117,300	$ 115,300	$ 117,300
Cleopatra
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	53.00%	53000000.00%	53.00%	53000000.00%
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	$ 2,600	$ 2,400	$ 4,200	$ 5,300
Income from equity method investments	1,900	1,200	3,000	3,200
Equity method investments	$ 113,100	$ 115,500	$ 113,100	$ 115,500
Proteus
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	65.00%	65000000.00%	65.00%	65000000.00%
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	$ 3,400	$ 5,200	$ 8,100	$ 10,700
Income from equity method investments	3,100	3,600	7,100	7,700
Equity method investments	$ 67,400	$ 72,300	$ 67,400	$ 72,300
Endymion
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	65.00%	65000000.00%	65.00%	65000000.00%
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	$ 6,600	$ 4,800	$ 14,600	$ 10,700
Income from equity method investments	6,400	5,200	13,900	11,200
Equity method investments	78,600	81,500	78,600	81,500
Others
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Proceeds From Equity Method Investment, Dividends Or Distributions, Return On Capital And Return Of Capital	2,900	2,300	3,900	4,300
Income from equity method investments	2,700	1,500	4,800	3,700
Equity method investments	$ 88,200	$ 85,600	$ 88,200	$ 85,600
Total Mardi Gras Joint Ventures
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	65.00%		65.00%
Ursa
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	22.70%		22.70%
KM Phoenix
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity Method Investment, Ownership Percentage	25.00%		25.00%

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 119,900	$ 111,700
Less: Accumulated depreciation	(45,100)	(43,800)
Property, plant and equipment, net	74,800	67,900
Impairment charge	0
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	200	200
Rights-of-way
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,400	1,400
Building and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	6,900	6,900
Pipeline and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	95,500	95,300
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment	900	800
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 15,000	$ 7,100

Other Current Liabilities (Deta

Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Current portion of environmental remediation obligations	$ 500	$ 400
Accrued interest payable – related parties	100	100
Current portion of environmental remediation obligation	800	900
Current portion of lease liabilities	1,700	2,300
Other current liabilities	8,200	7,800
Accrued Liabilities and Other Liabilities	$ 5,100	$ 4,100

Debt (Details)

Debt (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Line of Credit Facility [Line Items]
Weighted average interest rate				2.28%
Long-term Debt, Gross	$ 468		$ 468
Required consolidated leverage ratio	5		5
Required consolidated leverage ratio temporary 1	5.5		5.5
Debt maximum borrowing capacity	$ 600		$ 600
Balance spread on variable rate	0.73%
Long-term Debt [Member]
Line of Credit Facility [Line Items]
Weighted average interest rate	0.92%		0.93%
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Outstanding borrowing	$ 468,000,000		$ 468,000,000		$ 468,000,000
Interest expense	$ 1,100,000	$ 2,000,000	$ 2,200,000	$ 5,600,000

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Related parties	$ 28,500,000	$ 30,700,000	$ 57,300,000	$ 60,400,000
Deferred revenues and credits – related parties	2,300,000		$ 2,300,000		$ 1,800,000
BP Pipelines
Related Party Transaction [Line Items]
Annual fee paid to related party	$ 15,500,000	14,000,000
Total Mardi Gras Joint Ventures
Related Party Transaction [Line Items]
Noncontrolling interest, ownership percentage by Parent	3500.00%		3500.00%
Parent
Related Party Transaction [Line Items]
Performance or restricted period			3 years
Parent [Member]
Related Party Transaction [Line Items]
Performance or restricted period	3 years
BP Products
Related Party Transaction [Line Items]
Deficiency revenue	$ 0	$ 6,000,000	$ 6,000,000	$ 0

Related Party Transactions - Sc

Related Party Transactions - Schedule of Related Party Transactions (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transactions [Abstract]
Operating expenses—related parties	$ 1,400,000	$ 1,300,000	$ 2,600,000	$ 2,800,000
Maintenance expenses—related parties	100,000	100,000	100,000	200,000
General and administrative—related parties	3,900,000	3,600,000	7,900,000	7,500,000
Total costs and expenses—related parties	5,400,000	5,000,000	10,600,000	10,500,000
BP Products
Related Party Transaction [Line Items]
Deficiency revenue	$ 0	$ 6,000,000	$ 6,000,000	$ 0

Net Income Per Limited Partne_3

Net Income Per Limited Partner Unit - Schedule of Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 13, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Distribution Made to Limited Partner [Line Items]
Partner distributions declared		$ 37,600	$ 37,600	$ 75,200	$ 75,200
General Partner
Distribution Made to Limited Partner [Line Items]
Partner distributions declared		1,200	1,200	2,400	2,400
Limited Partners Common Units
Distribution Made to Limited Partner [Line Items]
Partner distributions declared		36,400	18,200	72,800	36,400
Limited Partners Subordinated Units
Distribution Made to Limited Partner [Line Items]
Partner distributions declared		$ 0	$ 18,200	$ 0	$ 36,400
Subsequent Event
Distribution Made to Limited Partner [Line Items]
Dividends declared per share (in dollars per share)	$ 0.3475

Net Income Per Limited Partne_4

Net Income Per Limited Partner Unit - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	$ 37,600	$ 37,600	$ 75,200	$ 75,200
Net income attributable to the Partnership in excess of distributions	2,900	3,000	7,300	7,100
Net income attributable to the Partnership	40,500	40,600	82,500	82,300
Incentive distribution rights currently held by the General Partner
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	1,200	1,200	2,400	2,400
Net income attributable to the Partnership in excess of distributions	0	0	0	0
Net income attributable to the Partnership	1,200	1,200	2,400	2,400
Limited partners' distribution declared on common units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	36,400	18,200	72,800	36,400
Net income attributable to the Partnership in excess of distributions	2,900	1,500	(2,200)	3,600
Net income attributable to the Partnership	$ 39,300	$ 19,700	$ 70,600	$ 40,000
Weighted average units outstanding:
Basic and Diluted (in shares)	104.8	52.4	92.6	52.4
Net income per limited partner unit (in dollars):
Basic and Diluted (in dollars per share)	$ 0.37	$ 0.38	$ 0.76	$ 0.77
Limited partners' distribution declared on subordinated units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Partner distributions declared	$ 0	$ 18,200	$ 0	$ 36,400
Net income attributable to the Partnership in excess of distributions	0	1,500	9,500	3,500
Net income attributable to the Partnership	$ 0	$ 19,700	$ 9,500	$ 39,900
Weighted average units outstanding:
Basic and Diluted (in shares)	0	52.4	52.4	52.4
Net income per limited partner unit (in dollars):
Basic and Diluted (in dollars per share)	$ 0	$ 0.38	$ 0.18	$ 0.77

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Site Contingency [Line Items]
Environmental liabilities	$ 3,500	$ 3,500	$ 3,400
Indemnification assets	3,500	3,500	$ 3,400
Impairment charge	0
Griffith Station [Member]
Site Contingency [Line Items]
Accrual for Environmental Loss Contingencies, Charges to Expense for New Losses	100	200
Accrual for Environmental Loss Contingencies, Charges to Expense for New Losses	$ 100	$ 200
Mars
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	28.50%	28.50%		28500000.00%
Mardi Gras Transportation System Company LLC
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	65.00%	65.00%
Caesar
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	56.00%	56.00%		56000000.00%
Cleopatra
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	53.00%	53.00%		53000000.00%
Endymion
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	65.00%	65.00%		65000000.00%
Proteus
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	65.00%	65.00%		65000000.00%
Ursa
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	22.70%	22.70%
KM Phoenix
Site Contingency [Line Items]
Equity Method Investment, Ownership Percentage	25.00%	25.00%

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Balance Sheet Classification of Environmental Liabilities and Indemnification Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Current portion of environmental remediation obligations	$ 500	$ 400
Long-term portion of environmental remediation obligations	3,000	3,000
Total	3,500	3,400
Current portion of indemnification assets	500	400
Non-current portion of indemnification assets	3,000	3,000
Total	$ 3,500	$ 3,400

Unit-Based Compensation - Narra

Unit-Based Compensation - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average recognition period			8 months 12 days
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	$ 56,000	$ 56,000	$ 111,000	$ 119,000
Unrecognized compensation cost related to phantom unit awards	$ 146,000		$ 146,000
Phantom Share Units (PSUs) | 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		5,502,271

Unit-Based Compensation - Phant

Unit-Based Compensation - Phantom Units Activity (Details) - Phantom Share Units (PSUs)	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Number of Units (in units)
Beginning balance outstanding (shares) | shares	16,038
Granted (in shares) | shares	18,534
Vested (in shares) | shares	(16,038)
Ending balance outstanding (shares) | shares	18,534
Weighted Average Grant Date Fair Value per Unit (in dollars)
Beginning balance outstanding (in dollars per share) | $ / shares	$ 14.03
Granted (in dollars per share) | $ / shares	12
Vested (in dollars per share) | $ / shares	14.03
Ending balance outstanding (in dollars per share) | $ / shares	$ 12

Variable Interest Entity (Detai

Variable Interest Entity (Details) - USD ($)	Oct. 30, 2017	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Equity method investments		$ 515,700,000	$ 526,500,000	$ 515,700,000	$ 526,500,000	$ 519,900,000
Non-controlling interests		131,000,000		131,000,000		132,500,000
Statement of operations
Income from equity method investments		28,600,000	26,800,000	58,900,000	58,100,000
Less: Net income attributable to non-controlling interests		5,400,000	4,800,000	11,200,000	10,600,000
Net income attributable to the Partnership		$ 40,500,000	40,600,000	82,500,000	82,300,000
Cash flows from operating activities
Distributions of earnings received from equity method investments				58,800,000	60,700,000
Cash flows from financing activities
Distributions to non-controlling interests				$ (12,700,000)	(12,200,000)
Mardi Gras Transportation System Company LLC | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Managing member interest (as a percent)	100.00%
Remainder of economic interest held by affiliate (as a percent)	1.00%
Mardi Gras Transportation System Company LLC
Cash flows from financing activities
Equity Method Investment, Ownership Percentage		65.00%		65.00%
Mardi Gras Transportation System Company LLC | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets of VIE		$ 0		$ 0		0
Balance Sheet Related Disclosures [Abstract]
Equity method investments		374,400,000		374,400,000		378,500,000
Non-controlling interests		131,000,000		131,000,000		$ 132,500,000
Statement of operations
Income from equity method investments		15,600,000	13,700,000	32,000,000	30,300,000
Less: Net income attributable to non-controlling interests		5,400,000	4,800,000	11,200,000	10,600,000
Net income attributable to the Partnership		$ 10,200,000	$ 8,900,000	20,800,000	19,700,000
Cash flows from operating activities
Distributions of earnings received from equity method investments				31,900,000	29,800,000
Cash flows from investing activities
Distribution in excess of earnings from equity method investments				4,200,000	5,200,000
Cash flows from financing activities
Distributions to non-controlling interests				(12,700,000)	(12,200,000)
Net change in cash and cash equivalents				$ 23,400,000	$ 22,800,000

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, $ in Millions	Aug. 13, 2020USD ($)$ / shares
Scenario, Forecast
Subsequent Event [Line Items]
Total distribution paid	$ 37.6
Dividends paid to non-affiliated common unitholders	16.6
Net transfers to Parent	21
Incentive distribution rights	$ 1.2
Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share (in dollars per share) | $ / shares	$ 0.3475

Uncategorized Items - bpmp-2021

Label	Element	Value
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	$ 6,400,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,700,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,500,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,300,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
General Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Member Units [Member] | BP Holdco [Member] | Subordinated Units [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	9,500,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	20,200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	19,700,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	0
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Member Units [Member] | General Public [Member] | Common Units [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	19,700,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	20,300,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	31,300,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	39,300,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	36,400,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Noncontrolling Interest [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	5,800,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	5,400,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	5,800,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	4,800,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,300,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,700,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,400,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	$ 5,500,000