10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 _____________________________________________

FORM 10-Q

 ____________________________________________

(Mark One)
☒	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2020

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

Commission file number 001-35714

_____________________________________________ 

MPLX LP

(Exact name of registrant as specified in its charter)

 _____________________________________________

	Delaware	27-0005456
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

200 E. Hardin Street,	Findlay,	Ohio	45840
(Address of principal executive offices)			(Zip code)

(419) 421-2414

(Registrant’s telephone number, including area code)

 _____________________________________________

Securities Registered pursuant to Section 12(b) of the Act
Title of each class	Trading symbol(s)	Name of each exchange on which registered
Common Units Representing Limited Partnership Interests	MPLX	New York Stock Exchange

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes  x     No  ¨

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files.) Yes  x    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	x	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act) Yes  ☐    No  x

MPLX LP had 1,058,750,442 common units outstanding at July 30, 2020.

Table of Contents

	Page
PART I – FINANCIAL INFORMATION
Item 1.   Financial Statements:
Consolidated Statements of Income (Unaudited)	3
Consolidated Statements of Comprehensive Income (Unaudited)	4
Consolidated Balance Sheets (Unaudited)	5
Consolidated Statements of Cash Flows (Unaudited)	6
Consolidated Statements of Equity (Unaudited)	7
Notes to Consolidated Financial Statements (Unaudited)	8
Item 2.   Management’s Discussion and Analysis of Financial Condition and Results of Operations	38
Item 3.   Quantitative and Qualitative Disclosures about Market Risk	62
Item 4.   Controls and Procedures	63
PART II – OTHER INFORMATION
Item 1.    Legal Proceedings	63
Item 1A. Risk Factors	64
Item 5. Other Information	64
Item 6.    Exhibits	66
Signatures	68

Unless the context otherwise requires, references in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “our,” “us,” or like terms refer to MPLX LP and its subsidiaries. Additionally, throughout this Quarterly Report on Form 10-Q, we have used terms in our discussion of the business and operating results that have been defined in our Glossary of Terms.

1

Glossary of Terms

The abbreviations, acronyms and industry technology used in this report are defined as follows.

ASC	Accounting Standards Codification
ASU	Accounting Standards Update
ATM Program	An at-the-market program for the issuance of common units
Barrel	One stock tank barrel, or 42 United States gallons of liquid volume, used in reference to crude oil or other liquid hydrocarbons
Bcf/d	One billion cubic feet per day
Btu	One British thermal unit, an energy measurement
Condensate	A natural gas liquid with a low vapor pressure mainly composed of propane, butane, pentane and heavier hydrocarbon fractions
DCF (a non-GAAP financial measure)	Distributable Cash Flow
EBITDA (a non-GAAP financial measure)	Earnings Before Interest, Taxes, Depreciation and Amortization
FASB	Financial Accounting Standards Board
GAAP	Accounting principles generally accepted in the United States of America
LIBOR	London Interbank Offered Rate
mbpd	Thousand barrels per day
Merger	MPLX acquisition by merger of Andeavor Logistics LP (“ANDX”) on July 30, 2019
MMBtu	One million British thermal units, an energy measurement
MMcf/d	One million cubic feet of natural gas per day
NGL	Natural gas liquids, such as ethane, propane, butanes and natural gasoline
NYSE	New York Stock Exchange
Predecessor	The related assets, liabilities and results of operations of Andeavor Logistics LP (“ANDX”) prior to the date of the acquisition, July 30, 2019, effective October 1, 2018
Realized derivative gain/loss	The gain or loss recognized when a derivative matures or is settled
SEC	United States Securities and Exchange Commission
SMR	Steam methane reformer, operated by a third party and located at the Javelina gas processing and fractionation complex in Corpus Christi, Texas
Unrealized derivative gain/loss	The gain or loss recognized on a derivative due to changes in fair value prior to the instrument maturing or settling
VIE	Variable interest entity

2

Part I—Financial Information

Item 1. Financial Statements

MPLX LP

Consolidated Statements of Income (Unaudited)

	Three Months Ended   June 30,					Six Months Ended   June 30,
(In millions, except per unit data)	2020		2019(1)			2020			2019(1)
Revenues and other income:
Service revenue	$	563	$	619		$	1,175		$	1,233
Service revenue - related parties	857		847			1,785			1,650
Service revenue - product related	22		26			61			60
Rental income	98		93			194			192
Rental income - related parties	237		286			471			611
Product sales	120		189			289			405
Product sales - related parties	30		36			63			77
Income/(loss) from equity method investments(2)	89		83			(1,095		)	160
Other income	2		4			3			4
Other income - related parties	63		27			127			53
Total revenues and other income	2,081		2,210			3,073			4,445
Costs and expenses:
Cost of revenues (excludes items below)	315		353			683			692
Purchased product costs	87		166			222			360
Rental cost of sales	33		29			68			66
Rental cost of sales - related parties	41		36			87			79
Purchases - related parties	280		313			556			591
Depreciation and amortization	321		313			646			614
Impairment expense	—		—			2,165			—
General and administrative expenses	96		90			193			191
Other taxes	30		25			61			55
Total costs and expenses	1,203		1,325			4,681			2,648
Income/(loss) from operations	878		885			(1,608		)	1,797
Related party interest and other financial costs	1		2			4			3
Interest expense (net of amounts capitalized of $10 million, $12 million, $23 million and $23 million, respectively)	206		214			417			428
Other financial costs	16		13			32			22
Income/(loss) before income taxes	655		656			(2,061		)	1,344
(Benefit)/provision for income taxes	—		(1		)	—			(2		)
Net income/(loss)	655		657			(2,061		)	1,346
Less: Net income attributable to noncontrolling interests	7		6			15			12
Less: Net income attributable to Predecessor	—		169			—			349
Net income/(loss) attributable to MPLX LP	648		482			(2,076		)	985
Less: Series A preferred unit distributions	21		21			41			41
Less: Series B preferred unit distributions	10		—			21			—
Limited partners’ interest in net income/(loss) attributable to MPLX LP	$	617	$	461		$	(2,138	)	$	944
Per Unit Data (See Note 6)
Net income/(loss) attributable to MPLX LP per limited partner unit:
Common - basic	$	0.58	$	0.56		$	(2.02	)	$	1.16
Common - diluted	$	0.58	$	0.55		$	(2.02	)	$	1.16
Weighted average limited partner units outstanding:
Common - basic	1,059		794			1,059			794
Common - diluted	1,059		795			1,059			795

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

The accompanying notes are an integral part of these consolidated financial statements.

3

MPLX LP

Consolidated Statements of Comprehensive Income (Unaudited)

	Three Months Ended   June 30,				Six Months Ended   June 30,
(In millions)	2020		2019(1)		2020			2019(1)
Net income/(loss)	$	655	$	657	$	(2,061	)	$	1,346
Other comprehensive income/(loss), net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	—		—		(1		)	1
Comprehensive income/(loss)	655		657		(2,062		)	1,347
Less comprehensive income attributable to:
Noncontrolling interests	7		6		15			12
Income attributable to Predecessor	—		169		—			349
Comprehensive income/(loss) attributable to MPLX LP	$	648	$	482	$	(2,077	)	$	986

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

The accompanying notes are an integral part of these consolidated financial statements.

4

MPLX LP

Consolidated Balance Sheets (Unaudited)

 

(In millions)	June 30, 2020			December 31, 2019
Assets
Current assets:
Cash and cash equivalents	$	67		$	15
Receivables, net	562			593
Current assets - related parties	594			656
Inventories	115			110
Other current assets	48			110
Total current assets	1,386			1,484
Equity method investments	4,065			5,275
Property, plant and equipment, net	21,758			22,145
Intangibles, net	1,023			1,270
Goodwill	7,722			9,536
Right of use assets, net	341			365
Noncurrent assets - related parties	676			303
Other noncurrent assets	51			52
Total assets	37,022			40,430
Liabilities
Current liabilities:
Accounts payable	145			242
Accrued liabilities	138			187
Current liabilities - related parties	372			1,008
Accrued property, plant and equipment	154			283
Accrued interest payable	207			210
Operating lease liabilities	69			66
Other current liabilities	143			136
Total current liabilities	1,228			2,132
Long-term deferred revenue	261			217
Long-term liabilities - related parties	287			290
Long-term debt	20,556			19,704
Deferred income taxes	11			12
Long-term operating lease liabilities	274			302
Deferred credits and other liabilities	175			192
Total liabilities	22,792			22,849
Commitments and contingencies (see Note 21)
Series A preferred units	968			968
Equity
Common unitholders - public (393 million and 392 million units issued and outstanding)	9,469			10,800
Common unitholder - MPC (666 million and 666 million units issued and outstanding)	2,951			4,968
Series B preferred units (.6 million and .6 million units issued and outstanding)	611			611
Accumulated other comprehensive loss	(16		)	(15		)
Total MPLX LP partners’ capital	13,015			16,364
Noncontrolling interests	247			249
Total equity	13,262			16,613
Total liabilities, preferred units and equity	$	37,022		$	40,430

The accompanying notes are an integral part of these consolidated financial statements.

5

MPLX LP

Consolidated Statements of Cash Flows (Unaudited)

	Six Months Ended   June 30,
(In millions)	2020			2019(1)
Increase/(decrease) in cash, cash equivalents and restricted cash
Operating activities:
Net (loss)/income	$	(2,061	)	$	1,346
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Amortization of deferred financing costs	29			19
Depreciation and amortization	646			614
Impairment expense	2,165			—
Deferred income taxes	(1		)	(2		)
Asset retirement expenditures	—			(1		)
Loss/(gain) on disposal of assets	1			(2		)
Loss/(income) from equity method investments(2)	1,095			(160		)
Distributions from unconsolidated affiliates	226			245
Changes in:
Current receivables	31			75
Inventories	(7		)	—
Fair value of derivatives	(9		)	7
Current accounts payable and accrued liabilities	(102		)	(117		)
Current assets/current liabilities - related parties	27			(124		)
Right of use assets/operating lease liabilities	(1		)	1
Deferred revenue	49			46
All other, net	26			7
Net cash provided by operating activities	2,114			1,954
Investing activities:
Additions to property, plant and equipment	(708		)	(1,136		)
Acquisitions, net of cash acquired	—			6
Disposal of assets	43			8
Investments in unconsolidated affiliates	(222		)	(323		)
Distributions from unconsolidated affiliates - return of capital	110			2
All other, net	—			4
Net cash used in investing activities	(777		)	(1,439		)
Financing activities:
Long-term debt - borrowings	2,500			3,139
- repayments	(1,682		)	(2,272		)
Related party debt - borrowings	2,708			3,833
- repayments	(3,302		)	(3,789		)
Distributions to noncontrolling interests	(17		)	(12		)
Distributions to Series A preferred unitholders	(41		)	(40		)
Distributions to Series B preferred unitholders	(21		)	—
Distributions to unitholders and general partner	(1,445		)	(1,038		)
Distributions to common and Series B preferred unitholders from Predecessor	—			(502		)
Contributions from MPC	20			28
Contributions from noncontrolling interests	—			94
All other, net	(5		)	(9		)
Net cash used in financing activities	(1,285		)	(568		)
Net increase/(decrease) in cash, cash equivalents and restricted cash	52			(53		)
Cash, cash equivalents and restricted cash at beginning of period	15			85
Cash, cash equivalents and restricted cash at end of period	$	67		$	32

(1) Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) The 2020 period includes $1,264 million of impairment expense. See Note 4.

The accompanying notes are an integral part of these consolidated financial statements.

6

MPLX LP

Consolidated Statements of Equity (Unaudited)

	Partnership
(In millions)	Common Unit-holders Public			Common Unit-holder MPC			Series B Preferred Unit-holders			Accumulated Other Comprehensive Loss			Non-controlling Interests			Equity of Predecessor			Total(1)
Balance at December 31, 2018	$	8,336		$	(1,612	)	$	—		$	(16	)	$	156		$	10,867		$	17,731
Net income (excludes amounts attributable to preferred units)	176			307			—			—			6			180			669
Distributions to:
Unitholders	(188		)	(327		)	—			—			—			(261		)	(776		)
Noncontrolling interests	—			—			—			—			(6		)	—			(6		)
Contributions from:
MPC	—			—			—			—			—			15			15
Noncontrolling interests	—			—			—			—			94			—			94
Other	2			—			—			1			—			—			3
Balance at March 31, 2019	8,326			(1,632		)	—			(15		)	250			10,801			17,730
Net income (excludes amounts attributable to preferred units)	168			293			—			—			6			169			636
Distributions to:
Unitholders	(191		)	(332		)	—			—			—			(241		)	(764		)
Noncontrolling interests	—			—			—			—			(6		)	—			(6		)
Contributions from:
MPC	—			—			—			—			—			13			13
Other	2			—			—			—			—			—			2
Balance at June 30, 2019	8,305			(1,671		)	—			(15		)	250			10,742			17,611
Balance at December 31, 2019	10,800			4,968			611			(15		)	249			—			16,613
Net (loss)/income (excludes amounts attributable to preferred units)	(1,022		)	(1,733		)	11			—			8			—			(2,736		)
Distributions to:
Unitholders	(271		)	(446		)	(21		)	—			—			—			(738		)
Noncontrolling interests	—			—			—			—			(9		)	—			(9		)
Contributions from:
MPC	—			225			—			—			—			—			225
Other	2			—			—			(1		)	—			—			1
Balance at March 31, 2020	9,509			3,014			601			(16		)	248			—			13,356
Net income (excludes amounts attributable to preferred units)	229			388			10			—			7			—			634
Distributions to:
Unitholders	(270		)	(458		)	—			—			—			—			(728		)
Noncontrolling interests	—			—			—			—			(8		)	—			(8		)
Contributions from:
MPC	—			6			—			—			—			—			6
Other	1			1			—			—			—			—			2
Balance at June 30, 2020	$	9,469		$	2,951		$	611		$	(16	)	$	247		$	—		$	13,262

(1) Financial information for the first and second quarters of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

The accompanying notes are an integral part of these consolidated financial statements.

7

Notes to Consolidated Financial Statements (Unaudited)

1. Description of the Business and Basis of Presentation

Description of the Business – MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to “MPC” refer collectively to Marathon Petroleum Corporation as our sponsor and its subsidiaries, other than the Partnership. We are engaged in the transportation, storage and distribution of crude oil, asphalt and refined petroleum products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.

MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, asphalt and refined petroleum products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 9 for additional information regarding the operations and results of these segments.

On July 30, 2019, MPLX completed its acquisition by merger (the “Merger”) of Andeavor Logistics LP (“ANDX”). At the effective time of the Merger, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. See Note 3 for additional information regarding the Merger.

Impairments – The outbreak of COVID-19 and its development into a pandemic in March 2020 resulted in significant economic disruption globally. Actions taken by various governmental authorities, individuals and companies around the world to prevent the spread of COVID-19 through social distancing have restricted travel, many business operations, public gatherings and the overall level of individual movement and in-person interaction across the globe. Although there have been some signs of economic improvement, these events significantly reduced global economic activity and resulted in a decline in the demand for the midstream services we provide beginning with the first quarter of 2020. Macroeconomic conditions and global geopolitical events have also resulted in significant price volatility related to those aforementioned products.

The overall deterioration in the economy and the environment in which MPLX and its customers operate, as well as a sustained decrease in unit price, were considered triggering events resulting in impairments of the carrying value of certain assets during the first quarter of 2020. We recognized impairments related to goodwill, certain equity method investments and certain long-lived assets (including intangibles), within our G&P segment. Many of our producer customers refined and updated production forecasts in response to the current environment, which impacted their current and expected future demand for our services, including the future utilization of our assets. Additionally, certain of our contracts have commodity price exposure, including NGL prices, which have experienced increased volatility as noted above. The table below provides information related to the impairments recognized during the first quarter of 2020 as well as the corresponding footnote where additional information can be found. No additional events or circumstances arose during the second quarter of 2020 which would indicate the need for any additional impairment beyond those recognized during the first quarter.

(In millions)	Impairment		Footnote Reference
Goodwill	$	1,814	12
Equity method investments	1,264		4
Intangibles, net	177		12
Property, plant and equipment, net	174		11
Total impairments	$	3,429

Basis of Presentation – The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain amounts in prior years have been reclassified to conform to current year presentation.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Annual Report on Form 10-K for the year ended December 31, 2019. The results of

8

operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results to be expected for the full year.

In relation to the Merger described above and in Note 3, ANDX’s assets, liabilities and results of operations prior to the Merger are collectively included in what we refer to as the “Predecessor” from October 1, 2018, which was the date that MPC acquired Andeavor. MPLX’s acquisition of ANDX is considered a transfer between entities under common control due to MPC’s relationship with ANDX prior to the Merger. As an entity under common control with MPC, MPLX recorded the assets acquired and liabilities assumed on its consolidated balance sheets at MPC’s historical carrying value. Transfers of businesses between entities under common control require prior periods to be retrospectively adjusted for those dates that the entity was under common control. Accordingly, the accompanying financial statements and related notes of MPLX LP have been retrospectively adjusted to include the historical results of ANDX beginning October 1, 2018.

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule. Distributions, although earned, are not accrued until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 6.

2. Accounting Standards

Recently Adopted

ASU 2016-13, Credit Losses - Measurement of Credit Losses on Financial Instruments

Effective January 1, 2020, we adopted ASU 2016-13 using the modified retrospective transition method. This ASU requires entities to consider a broader range of information to estimate expected credit losses, which may result in earlier recognition of losses. The ASU requires the company to utilize an expected loss methodology in place of the incurred loss methodology for financial instruments, including trade receivables, and off-balance sheet credit exposures. Adoption of the standard did not have a material impact on our financial statements.

We are exposed to credit losses, primarily as a result of the midstream services that we provide. We assess each customer’s ability to pay through our credit review process, which considers various factors such as external credit ratings; a review of financial statements to determine liquidity, leverage, trends and business specific risks; market information; pay history and our business strategy. We monitor our ongoing credit exposure through timely review of customer payment activity. At June 30, 2020, we reported $562 million of accounts receivable, net of allowances of $1 million.

We also adopted the following ASU’s during the first six months of 2020, which did not have a material impact to our financial statements or financial statement disclosures:

ASU		Effective Date
2018-13	Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement	January 1, 2020
2020-04	Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting	April 1, 2020

9

3. Acquisitions

Acquisition of Andeavor Logistics LP

As previously disclosed, on May 7, 2019, ANDX, Tesoro Logistics GP, LLC (then the general partner of ANDX (“TLGP”)), MPLX, MPLX GP LLC (the general partner of MPLX (“MPLX GP”)), and MPLX MAX LLC, a wholly owned subsidiary of MPLX (“Merger Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) that provided for, among other things, the merger of Merger Sub with and into ANDX. On July 30, 2019, the Merger was completed, and ANDX survived the Merger as a wholly owned subsidiary of MPLX. At the effective time of the Merger, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. See Note 7 for information on units issued in connection with the Merger.

Additionally, as a result of the Merger, each ANDX TexNew Mex Unit issued and outstanding immediately prior to the effective time of the Merger was converted into a right for Western Refining Southwest, Inc. (“WRSW”), a wholly owned subsidiary of MPC, as the holder of all such units, to receive a unit representing a substantially equivalent limited partner interest in MPLX (the “MPLX TexNew Mex Units”). By virtue of the conversion, all ANDX TexNew Mex Units were cancelled and ceased to exist as of the effective time of the Merger. The MPLX TexNew Mex Units are a new class of units in MPLX substantially equivalent to the ANDX TexNew Mex Units, including substantially equivalent rights, powers, duties and obligations that the ANDX TexNew Mex Units had immediately prior to the closing of the Merger.

As a result of the Merger, the ANDX Special Limited Partner Interest outstanding immediately prior to the effective time of the Merger was converted into a right for Southwest Inc., as the holder of all such interest, to receive a substantially equivalent special limited partner interest in MPLX (the “MPLX Special Limited Partner Interest”). By virtue of the conversion, the ANDX Special Limited Partner Interest was cancelled and ceased to exist as of the effective time of the Merger. For information on ANDX’s preferred units, please see Note 7.

The assets of ANDX consist of a network of owned and operated crude oil, refined product and natural gas pipelines; crude oil and water gathering systems; refining logistics assets; terminals with crude oil and refined products storage capacity; rail facilities; marine terminals including storage; bulk petroleum distribution facilities; a trucking fleet; and natural gas processing and fractionation systems and complexes. The assets are located in the western and inland regions of the United States and complement MPLX’s existing business and assets.

MPC accounted for its October 1, 2018 acquisition of Andeavor (including acquiring control of ANDX), using the acquisition method of accounting, which required Andeavor assets and liabilities to be recorded by MPC at the acquisition date fair value. The Merger was closed on July 30, 2019, and the results of ANDX have been incorporated into the results of MPLX as of October 1, 2018, which is the date that common control was established. As a result of MPC’s relationship with both MPLX and ANDX, the Merger has been treated as a common control transaction, which requires the recasting of MPLX’s historical results and the recognition of assets acquired and liabilities assumed using MPC’s historical carrying value. We recognized $5 million in acquisition costs during the first half of 2019 related to the Merger, which are reflected in general and administrative expenses. For the three and six months ended June 30, 2019, we recognized $588 million and $1,177 million of revenues and other income, respectively, related to ANDX. For the three and six months ended June 30, 2019 we recognized $168 million and $348 million, respectively, of net income related to ANDX.

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4. Investments and Noncontrolling Interests

The following table presents MPLX’s equity method investments at the dates indicated:

	Ownership as of	Carrying value at
	June 30,	June 30,		December 31,
(In millions, except ownership percentages)	2020	2020		2019
L&S
MarEn Bakken Company LLC(1)	25%	$	477	$	481
Illinois Extension Pipeline Company, L.L.C.	35%	268		265
LOOP LLC	41%	242		238
Andeavor Logistics Rio Pipeline LLC(2)	67%	196		202
Minnesota Pipe Line Company, LLC	17%	190		190
Whistler Pipeline LLC(2)	38%	188		134
Explorer Pipeline Company	25%	79		83
W2W Holdings LLC(2)(3)	50%	77		—
Wink to Webster Pipeline LLC(2)(3)	15%	—		126
Other(2)		60		55
Total L&S		1,777		1,774
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	725		1,984
Sherwood Midstream LLC(2)	50%	560		537
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	308		302
Rendezvous Gas Services, L.L.C.(2)	78%	166		170
Sherwood Midstream Holdings LLC(2)	51%	152		157
Centrahoma Processing LLC	40%	151		153
Other(2)		226		198
Total G&P		2,288		3,501
Total		$	4,065	$	5,275

(1) The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.    

(2) Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

(3) During the six months ended June 30, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

For those entities that have been deemed to be VIEs, neither MPLX nor any of its subsidiaries have been deemed to be the primary beneficiary due to voting rights on significant matters. While we have the ability to exercise influence through participation in the management committees which make all significant decisions, we have equal influence over each committee as a joint interest partner and all significant decisions require the consent of the other investors without regard to economic interest and as such we have determined that these entities should not be consolidated and apply the equity method of accounting with respect to our investments in each entity.

Sherwood Midstream has been deemed the primary beneficiary of Sherwood Midstream Holdings due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. Therefore, MPLX also reports its portion of Sherwood Midstream Holdings’ net assets as a component of its investment in Sherwood Midstream. As of June 30, 2020, MPLX has a 24.47 percent indirect ownership interest in Sherwood Midstream Holdings through Sherwood Midstream.

MPLX’s maximum exposure to loss as a result of its involvement with equity method investments includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. MPLX did not provide any financial support to equity method investments that it was not contractually obligated to provide during the six months ended June 30, 2020.

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During the first quarter of 2020, we recorded an other than temporary impairment for three joint ventures in which we have an interest as discussed in Note 1. Impairment of these investments was $1,264 million, of which $1,251 million was related to MarkWest Utica EMG, L.L.C. and its investment in Ohio Gathering Company, L.L.C. The fair value of the investments was determined based upon applying the discounted cash flow method, which is an income approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future cash flows, including prices and volumes, the weighted average cost of capital and the long-term growth rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As such, the fair value of these equity method investments represents a Level 3 measurement. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment test will prove to be an accurate prediction of the future. The impairment was recorded through “Income from equity method investments.” The impairments were largely due to a reduction in forecasted volumes gathered and processed by the systems operated by the joint ventures. There were no additional impairments recorded during the second quarter of 2020.

Summarized financial information for MPLX’s equity method investments for the six months ended June 30, 2020 and 2019 is as follows:

	Six Months Ended June 30, 2020
(In millions)	VIEs			Non-VIEs		Total
Revenues and other income	$	(43	)	$	640	$	597
Costs and expenses	202			274		476
Income from operations	(245		)	366		121
Net income	(283		)	332		49
(Loss)/income from equity method investments(1)	$	(1,178	)	$	83	$	(1,095	)

(1) Includes the impact of any basis differential amortization or accretion in addition to the impairment of $1,264 million.

	Six Months Ended June 30, 2019(1)
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	306	$	724	$	1,030
Costs and expenses	159		295		454
Income from operations	147		429		576
Net income	127		383		510
Income from equity method investments(2)	$	54	$	106	$	160

(1) Financial information for the first six months of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Includes the impact of any basis differential amortization or accretion.

Summarized balance sheet information for MPLX’s equity method investments as of June 30, 2020 and December 31, 2019 is as follows:

	June 30, 2020
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	357	$	317	$	674
Noncurrent assets	5,824		5,061		10,885
Current liabilities	265		181		446
Noncurrent liabilities	$	656	$	853	$	1,509

	December 31, 2019
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	534	$	330	$	864
Noncurrent assets	5,862		5,134		10,996
Current liabilities	192		245		437
Noncurrent liabilities	$	305	$	822	$	1,127

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As of June 30, 2020, the underlying net assets of MPLX’s investees in the G&P segment exceeded the carrying value of its equity method investments by approximately $59 million. At December 31, 2019, the carrying value of MPLX’s equity method investments in the G&P segment exceeded the underlying net assets of its investees by approximately $1.0 billion. As of June 30, 2020 and December 31, 2019, the carrying value of MPLX’s equity method investments in the L&S segment exceeded the underlying net assets of its investees by $330 million and $329 million, respectively. At June 30, 2020 and December 31, 2019, the G&P basis difference was being amortized into net income over the remaining estimated useful lives of the underlying assets, except for $31 million and $498 million of excess related to goodwill, respectively. At June 30, 2020 and December 31, 2019, the L&S basis difference was being amortized into net income over the remaining estimated useful lives of the underlying assets, except for $167 million of excess related to goodwill.

5. Related Party Agreements and Transactions

MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below.

MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum throughput volumes on crude oil and refined products and other fees for storage capacity; operating and management fees; as well as reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under the marine transportation service agreement. MPLX also has a keep-whole commodity agreement with MPC under which MPC pays us a processing fee for NGLs related to keep-whole agreements and delivers shrink gas to the producers on our behalf. We pay MPC a marketing fee in exchange for assuming the commodity risk. Additionally, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services-type agreements as well as other various agreements.

Related Party Loan

MPLX is party to a loan agreement with MPC Investment LLC (“MPC Investment”) (the “MPC Loan Agreement”). Under the terms of the agreement, MPC Investment makes a loan or loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC Investment. In connection with the Merger, on July 31, 2019, MPLX and MPC Investment amended and restated the MPC Loan Agreement to increase the borrowing capacity under the MPC Loan Agreement to $1.5 billion in aggregate principal amount of all loans outstanding at any one time. The entire unpaid principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), shall become due and payable on July 31, 2024, provided that MPC Investment may demand payment of all or any portion of the outstanding principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), at any time prior to July 31, 2024. Borrowings under the MPC Loan Agreement prior to July 31, 2019 bore interest at LIBOR plus 1.50 percent while borrowings as of and after July 31, 2019 bear interest at LIBOR plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 15. Activity on the MPC Loan Agreement was as follows:

(In millions)	Six Months Ended June 30, 2020			Year Ended December 31, 2019
Borrowings	$	2,708		$	8,540
Average interest rate of borrowings	2.733		%	3.441		%
Repayments	$	3,302		$	7,946
Outstanding balance at end of period(1)	$	—		$	594

(1) Included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

Prior to the Merger, ANDX was also party to a loan agreement with MPC (“ANDX-MPC Loan Agreement”). This facility was entered into on December 21, 2018, with a borrowing capacity of $500 million. In connection with the Merger, on July 31, 2019, MPLX repaid the entire outstanding balance and terminated the ANDX-MPC Loan Agreement. Activity on the ANDX-MPC Loan Agreement prior to the Merger was as follows:

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(In millions)	Year Ended December 31, 2019
Borrowings	$	773
Average interest rate of borrowings	4.249		%
Repayments	$	773
Outstanding balance at end of period	$	—

Related Party Revenue

Related party sales to MPC consist of crude oil and refined products pipeline and trucking transportation services based on tariff/contracted rates; storage, terminal and fuels distribution services based on contracted rates; and marine transportation services. Related party sales to MPC also consist of revenue related to volume deficiency credits.

MPLX also has operating agreements with MPC under which it receives a fee for operating MPC’s retained pipeline assets and a fixed annual fee for providing oversight and management services required to run the marine business. MPLX also receives management fee revenue for engineering, construction and administrative services for operating certain of its equity method investments.

Revenue received from related parties included on the Consolidated Statements of Income was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Service revenues - related parties
MPC	$	857	$	847	$	1,784	$	1,650
Other	—		—		1		—
Total Service revenue - related parties	857		847		1,785		1,650
Rental income - related parties
MPC	237		286		471		611
Product sales - related parties(1)
MPC	30		36		63		77
Other income - related parties
MPC	48		10		96		20
Other	15		17		31		33
Total Other income - related parties	$	63	$	27	$	127	$	53

(1) There were additional product sales to MPC that net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and six months ended June 30, 2020, these sales totaled $52 million and $225 million. For the three and six months ended June 30, 2019, these sales totaled $295 million and $518 million.

Related Party Expenses

MPC provides executive management services and certain general and administrative services to MPLX under the terms of our omnibus agreements (“Omnibus charges”). Omnibus charges included in “Rental cost of sales - related parties” primarily relate to services that support MPLX’s rental operations and maintenance of assets available for rent. Omnibus charges included in “Purchases - related parties” primarily relate to services that support MPLX’s operations and maintenance activities, as well as compensation expenses. Omnibus charges included in “General and administrative expenses” primarily relate to services that support MPLX’s executive management, accounting and human resources activities. MPLX also obtains employee services from MPC under employee services agreements (“ESA charges”). ESA charges for personnel directly involved in or supporting operations and maintenance activities related to rental services are classified as “Rental cost of sales - related parties.” ESA charges for personnel directly involved in or supporting operations and maintenance activities related to other services are classified as “Purchases - related parties.” ESA charges for personnel involved in executive management, accounting and human resources activities are classified as “General and administrative expenses.” In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain lease agreements with MPC.

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Expenses incurred from MPC under the omnibus and employee services agreements as well as other purchases from MPC included on the Consolidated Statements of Income are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Rental cost of sales - related parties
MPC	$	41	$	36	$	87	$	79
Purchases - related parties
MPC	276		308		547		581
Other	4		5		9		10
Total Purchase - related parties	280		313		556		591
General and administrative expenses
MPC	$	68	$	53	$	132	$	115

Some charges incurred under the omnibus and ESA agreements are related to engineering services and are associated with assets under construction. These charges are added to “Property, plant and equipment, net” on the Consolidated Balance Sheets. For the three and six months ended June 30, 2020, these charges totaled $15 million and $51 million, respectively. For the three and six months ended June 30, 2019, these charges totaled $38 million and $79 million, respectively.

Related Party Assets and Liabilities

Assets and liabilities with related parties appearing on the Consolidated Balance Sheets are detailed in the table below. This table identifies the various components of related party assets and liabilities, including those associated with leases (see Note 20 for additional information) and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts are recorded as “Current liabilities - related parties.” In many cases, MPC may then apply the amount of any such deficiency payments as a credit for volumes in excess of its minimum volume commitment in future periods under the terms of the applicable agreements. MPLX recognizes related party revenues for the deficiency payments when credits are used for volumes in excess of minimum quarterly volume commitments, where it is probable the customer will not use the credit in future periods or upon the expiration of the credits. The use or expiration of the credits is a decrease in “Current liabilities - related parties.” In addition, capital projects MPLX is undertaking at the request of MPC are reimbursed in cash and recognized in income over the remaining term of the applicable agreements or in some cases as an equity contribution from its sponsor.

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(In millions)	June 30, 2020		December 31, 2019
Current assets - related parties
Receivables - MPC	$	547	$	621
Receivables - Other	7		22
Prepaid - MPC	11		9
Other - MPC	1		—
Lease Receivables - MPC	28		4
Total	594		656
Noncurrent assets - related parties
Long-term receivables - MPC	30		21
Right of use assets - MPC	231		232
Long-term lease receivables - MPC	395		43
Unguaranteed residual asset - MPC	20		7
Total	676		303
Current liabilities - related parties
Payables - MPC	260		911
Payables - Other	36		37
Operating lease liabilities - MPC	1		1
Deferred revenue - Minimum volume deficiencies - MPC	56		42
Deferred revenue - Project reimbursements - MPC	18		16
Deferred revenue - Project reimbursements - Other	1		1
Total	372		1,008
Long-term liabilities - related parties
Long-term operating lease liabilities - MPC	230		230
Long-term deferred revenue - Project reimbursements - MPC	51		53
Long-term deferred revenue - Project reimbursements - Other	6		7
Total	$	287	$	290

Other Related Party Transactions

From time to time, MPLX may also sell to or purchase from related parties, assets and inventory at the lesser of average unit cost or net realizable value. Sales to and purchases from related parties were not material for the six months ended June 30, 2020 and 2019.

6. Net Income/(Loss) Per Limited Partner Unit

Net income/(loss) per unit applicable to common units is computed by dividing net income/(loss) attributable to MPLX LP less income/(loss) allocated to participating securities by the weighted average number of common units outstanding. Additional MPLX common units, MPLX Series B preferred units, and TexNew Mex units were issued on July 30, 2019 as a result of the merger with ANDX as discussed in Note 3. Distributions declared on these newly issued common and Series B preferred units are a reduction to income available to MPLX common unit holders due to their participation in distributions of income.

16

Classes of participating securities for the three and six months ended June 30, 2020 and 2019 include:

	Six Months Ended June 30,
	2020	2019
Common Units	ü	ü
Equity-based compensation awards	ü	ü
Series A preferred units	ü	ü
Series B preferred units	ü	ü

For the three and six months ended June 30, 2020 and 2019, MPLX had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three and six months ended June 30, 2020 and 2019 were less than 1 million.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019			2020			2019
Net income/(loss) attributable to MPLX LP	$	648		$	482		$	(2,076	)	$	985
Less: Distributions declared on Series A preferred units(1)	21			21			41			41
Distributions declared on Series B preferred units(1)	10			21			21			21
Limited partners’ distributions declared on MPLX common units (including common units of general partner)(1)(2)	715			692			1,443			1,215
Undistributed net loss attributable to MPLX LP	$	(98	)	$	(252	)	$	(3,581	)	$	(292	)

(1) See Note 7 for distribution information.

(2) The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

	Three Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	715		$	21	$	10	$	746
Undistributed net loss attributable to MPLX LP	(98		)	—		—		(98		)
Net income attributable to MPLX LP(1)	$	617		$	21	$	10	$	648
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.58
Diluted	$	0.58

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

17

	Three Months Ended June 30, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	692		$	21	$	21	$	734
Undistributed net loss attributable to MPLX LP	(252		)	—		—		(252		)
Net income attributable to MPLX LP(1)	$	440		$	21	$	21	$	482
Weighted average units outstanding:
Basic(2)	794
Diluted(2)	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.56
Diluted	$	0.55

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

(2) The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the three months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

	Six Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,443		$	41	$	21	$	1,505
Undistributed net loss attributable to MPLX LP	(3,581		)	—		—		(3,581		)
Net (loss)/income attributable to MPLX LP(1)	$	(2,138	)	$	41	$	21	$	(2,076	)
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	(2.02	)
Diluted	$	(2.02	)

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

18

	Six Months Ended June 30, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,215		$	41	$	21	$	1,277
Undistributed net loss attributable to MPLX LP	(292		)	—		—		(292		)
Net income attributable to MPLX LP(1)	$	923		$	41	$	21	$	985
Weighted average units outstanding:
Basic(2)	794
Diluted(2)	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.16
Diluted	$	1.16

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

(2) The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the six months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

7. Equity

The changes in the number of common units outstanding during the six months ended June 30, 2020 are summarized below:

(In units)	Common
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	253,291
Balance at June 30, 2020	1,058,608,762

Merger

In connection with the Merger and as discussed in Note 3, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units while ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. This resulted in the issuance of MPLX common units of approximately 102 million units to public unitholders and approximately 161 million units to MPC on July 30, 2019.

Series B Preferred Units

Prior to the Merger, ANDX had outstanding 600,000 units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of ANDX at a price to the public of $1,000 per unit. Upon completion of the Merger, the ANDX preferred units converted to preferred units of MPLX representing substantially equivalent limited partnership interests in MPLX (the “Series B preferred units”). The Series B preferred units are pari passu with the Series A preferred units with respect to distribution rights and rights upon liquidation. Distributions on the Series B preferred units are payable semi-annually in arrears on the 15th day, or the first business day thereafter, of February and August of each year up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent.

The changes in the Series B preferred unit balance from December 31, 2019 through June 30, 2020 are summarized below. Series B preferred units are included in the Consolidated Balance Sheets and Consolidated Statements of Equity within “Equity of Predecessor” for the period prior to the Merger and within “Series B preferred units” for the period following the Merger.

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(In millions)	Series B Preferred Units
Balance at December 31, 2019	$	611
Net income allocated	21
Distributions received by Series B preferred unitholders	(21		)
Balance at June 30, 2020	$	611

TexNew Mex Units - Prior to the Merger, MPC held 80,000 Andeavor Logistics TexNew Mex units, representing all outstanding units. At the time of the Merger, each Andeavor Logistics TexNew Mex unit was automatically converted into TexNew Mex units of MPLX with substantially the same rights and obligations as the Andeavor Logistics TexNew Mex units. The TexNew Mex units represent the right to receive quarterly distribution payments in an amount calculated using the distributable cash flow generated by a particular portion of the TexNew Mex pipeline system, in excess of a base amount and adjusted for previously agreed upon stipulations and contingencies. In the fourth quarter of 2019, distributions of less than $1 million were earned by the TexNew Mex units, which were declared in January of 2020 and paid in February 2020. Distributions of $2 million were earned by the TexNew Mex units during the three months ended June 30, 2020.

Cash distributions – In accordance with the MPLX partnership agreement, on July 28, 2020, MPLX declared a quarterly cash distribution for the second quarter of 2020, totaling $715 million, or $0.6875 per common unit. This rate will also be received by Series A preferred unitholders. These distributions will be paid on August 14, 2020 to common unitholders of record on August 7, 2020. Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the Board of Directors. Accordingly, a cash distribution payment totaling $21 million will be paid to Series B unitholders on August 17, 2020.

Quarterly distributions for 2020 and 2019 are summarized below:

(Per common unit)	2020		2019
March 31,	$	0.6875	$	0.6575
June 30,	$	0.6875	$	0.6675

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and six months ended June 30, 2020 and 2019. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	715	$	692	$	1,443	$	1,215
Series A preferred unit distributions	21		21		41		41
Series B preferred unit distributions	10		21		21		21
Total cash distributions declared	$	746	$	734	$	1,505	$	1,277

The distribution on common units for the three and six months ended June 30, 2019 includes the impact of the issuance of approximately 102 million units issued to public unitholders and approximately 161 million units issued to MPC in connection with the Merger. Due to the timing of the closing, distributions presented in the table above include second quarter distributions on MPLX common units issued to former ANDX unitholders and Series B Unitholders in connection with the Merger. The distributions on common units exclude $12.5 million of waived distributions for the three and six months ended June 30, 2019.

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8. Series A Preferred Units

On May 13, 2016, MPLX LP issued approximately 30.8 million 6.5 percent Series A Convertible preferred units for a cash purchase price of $32.50 per unit. The Series A preferred units rank senior to all common units and pari passu with all Series B preferred units with respect to distributions and rights upon liquidation. The holders of the Series A preferred units are entitled to receive, when and if declared by the board, a quarterly distribution equal to the greater of $0.528125 per unit or the amount of distributions they would have received on an as converted basis. On July 28, 2020, MPLX declared a quarterly cash distribution of $0.6875 per common unit for the second quarter of 2020. Holders of the Series A preferred units will receive the common unit rate in lieu of the lower $0.528125 base amount.

The holders may convert their Series A preferred units into common units at any time, in full or in part, subject to minimum conversion amounts and conditions. After the fourth anniversary of the issuance date, MPLX may convert the Series A preferred units into common units at any time, in whole or in part, subject to certain minimum conversion amounts and conditions, if the closing price of MPLX LP common units is greater than $48.75 for the 20-day trading period immediately preceding the conversion notice date. The conversion rate for the Series A preferred units shall be the quotient of (a) the sum of (i) $32.50, plus (ii) any unpaid cash distributions on the applicable preferred unit, divided by (b) $32.50, subject to adjustment for unit distributions, unit splits and similar transactions. The holders of the Series A preferred units are entitled to vote on an as-converted basis with the common unitholders and have certain other class voting rights with respect to any amendment to the MPLX partnership agreement that would adversely affect any rights, preferences or privileges of the preferred units. In addition, upon certain events involving a change of control, the holders of preferred units may elect, among other potential elections, to convert their Series A preferred units to common units at the then change of control conversion rate.

Approximately 29.6 million Series A preferred units remaining outstanding as of June 30, 2020. The changes in the redeemable preferred balance from December 31, 2019 through June 30, 2020 are summarized below:

(In millions)	Redeemable Series A Preferred Units
Balance at December 31, 2019	$	968
Net income allocated	41
Distributions received by Series A preferred unitholders	(41		)
Balance at June 30, 2020	$	968

The Series A preferred units are considered redeemable securities under GAAP due to the existence of redemption provisions upon a deemed liquidation event which is outside MPLX’s control. Therefore, they are presented as temporary equity in the mezzanine section of the Consolidated Balance Sheets. The Series A preferred units have been recorded at their issuance date fair value, net of issuance costs. Income allocations increase the carrying value and declared distributions decrease the carrying value of the Series A preferred units. As the Series A preferred units are not currently redeemable and not probable of becoming redeemable, adjustment to the initial carrying amount is not necessary and would only be required if it becomes probable that the Series A preferred units would become redeemable.

9. Segment Information

MPLX’s chief operating decision maker is the chief executive officer (“CEO”) of its general partner. The CEO reviews MPLX’s discrete financial information, makes operating decisions, assesses financial performance and allocates resources on a type of service basis. MPLX has two reportable segments: L&S and G&P. Each of these segments is organized and managed based upon the nature of the products and services it offers.

• L&S – transports, stores, distributes and markets crude oil, asphalt, refined petroleum products and water. Also includes an inland marine business, terminals, rail facilities, storage caverns and refining logistics.

• G&P – gathers, processes and transports natural gas; and gathers, transports, fractionates, stores and markets NGLs.

Our CEO evaluates the performance of our segments using Segment Adjusted EBITDA. Amounts included in net income and excluded from Segment Adjusted EBITDA include: (i) depreciation and amortization; (ii) provision/(benefit) for income taxes; (iii) amortization of deferred financing costs; (iv) extinguishment of debt; (v) non-cash equity-based compensation; (vi) impairment expense; (vii) net interest and other financial costs; (viii) income/(loss) from equity method investments; (ix) distributions and adjustments related to equity method investments; (x) unrealized derivative gains/(losses); (xi) acquisition costs; (xii) noncontrolling interest; and (xiii) other adjustments as deemed necessary. These items are either: (i) believed to be

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non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about revenues and other income, capital expenditures and investments in unconsolidated affiliates as well as total assets for our reportable segments:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019(1)		2020			2019(1)
L&S
Service revenue	$	931	$	922	$	1,935		$	1,811
Rental income	246		296		488			631
Product related revenue	21		20		40			35
Income from equity method investments	40		54		90			99
Other income	52		16		103			28
Total segment revenues and other income(2)	1,290		1,308		2,656			2,604
Segment Adjusted EBITDA(3)	839		570		1,711			1,129
Capital expenditures	108		230		292			428
Investments in unconsolidated affiliates	74		61		128			68
G&P
Service revenue	489		544		1,025			1,072
Rental income	89		83		177			172
Product related revenue	151		231		373			507
Income/(loss) from equity method investments	49		29		(1,185		)	61
Other income	13		15		27			29
Total segment revenues and other (loss)/income(2)	791		902		417			1,841
Segment Adjusted EBITDA(3)	388		350		810			721
Capital expenditures	110		326		244			632
Investments in unconsolidated affiliates	$	57	$	127	$	94		$	255

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

(3) See below for the reconciliation from Segment Adjusted EBITDA to net income.

(In millions)	June 30, 2020		December 31, 2019
Segment assets
Cash and cash equivalents	$	67	$	15
L&S	21,308		20,810
G&P	15,647		19,605
Total assets	$	37,022	$	40,430

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The table below provides a reconciliation between net (loss)/income and Segment Adjusted EBITDA.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019(1)			2020			2019(1)
Reconciliation to Net (loss)/income:
L&S Segment Adjusted EBITDA	$	839		$	570		$	1,711		$	1,129
G&P Segment Adjusted EBITDA	388			350			810			721
Total reportable segments	1,227			920			2,521			1,850
Depreciation and amortization(2)	(321		)	(313		)	(646		)	(614		)
Benefit for income taxes	—			1			—			2
Amortization of deferred financing costs	(15		)	(12		)	(29		)	(19		)
Non-cash equity-based compensation	(3		)	(5		)	(8		)	(12		)
Impairment expense	—			—			(2,165		)	—
Net interest and other financial costs	(208		)	(217		)	(424		)	(434		)
Income/(loss) from equity method investments	89			83			(1,095		)	160
Distributions/adjustments related to equity method investments	(115		)	(132		)	(239		)	(254		)
Unrealized derivative (losses)/gains(3)	(6		)	—			9			(4		)
Acquisition costs	—			(4		)	—			(5		)
Other	(1		)	—			(2		)	—
Adjusted EBITDA attributable to noncontrolling interests	8			7			17			14
Adjusted EBITDA attributable to Predecessor(4)	—			329			—			662
Net (loss)/income	$	655		$	657		$	(2,061	)	$	1,346

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Depreciation and amortization attributable to L&S was $138 million and $276 million for the three and six months ended June 30, 2020, respectively, and $134 million and $260 million for the three and six months ended June 30, 2019, respectively. Depreciation and amortization attributable to G&P was $183 million and $370 million for the three and six months ended June 30, 2020, respectively, and $179 million and $354 million for the three and six months ended June 30, 2019, respectively.

(3) MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

(4) The adjusted EBITDA adjustments related to Predecessor are excluded from adjusted EBITDA attributable to MPLX LP prior to the Merger.

10. Inventories

Inventories consist of the following:

(In millions)	June 30, 2020		December 31, 2019
NGLs	$	2	$	5
Line fill	8		10
Spare parts, materials and supplies	105		95
Total inventories	$	115	$	110

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11. Property, Plant and Equipment

Property, plant and equipment with associated accumulated depreciation is shown below:

(In millions)	Estimated Useful Lives	June 30, 2020		December 31, 2019
L&S
Pipelines	2-51 years	$	5,719	$	5,572
Refining Logistics	13-40 years	2,324		2,870
Terminals	4-40 years	1,281		1,109
Marine	15-20 years	960		906
Land, building and other	1-61 years	1,834		1,817
Construction-in progress		520		660
Total L&S property, plant and equipment		12,638		12,934
G&P
Gathering and transportation	5-40 years	7,374		7,159
Processing and fractionation	15-40 years	5,923		5,545
Land, building and other	3-40 years	489		484
Construction-in-progress		368		745
Total G&P property, plant and equipment		14,154		13,933
Total property, plant and equipment		26,792		26,867
Less accumulated depreciation(1)		5,034		4,722
Property, plant and equipment, net		$	21,758	$	22,145

(1) The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020 as discussed below.

Long-lived assets used in operations are assessed for impairment whenever changes in facts and circumstances indicate that the carrying value of the assets may not be recoverable based on the expected undiscounted future cash flow of an asset group. For purposes of impairment evaluation, long-lived assets must be grouped at the lowest level for which independent cash flows can be identified, which is at least at the segment level and in some cases for similar assets in the same geographic region where cash flows can be separately identified. If the sum of the undiscounted cash flows is less than the carrying value of an asset group, fair value is calculated, and the carrying value is written down if greater than the calculated fair value.

No impairment triggers were identified in the second quarter of 2020; however, during the first quarter of 2020, we did identify an impairment trigger relating to asset groups within our Western G&P reporting unit as a result of significant impacts to forecasted cash flows for these asset groups resulting from the first quarter events and circumstances as discussed in Note 1. The cash flows associated with these assets were significantly impacted by volume declines reflecting decreased forecasted producer customer production as a result of lower commodity prices. After assessing each asset group within the Western G&P reporting unit for impairment, only the East Texas G&P asset group resulted in the fair value of the underlying assets being less than the carrying value. As a result, an impairment of $174 million was recorded to “Impairment expense” on the Consolidated Statements of Income in the first quarter of 2020. Fair value of the assets was determined using a combination of an income and cost approach. The income approach utilized significant assumptions including management’s best estimates of the expected future cash flows, the estimated useful life of the asset group and discount rate. The cost approach utilized assumptions for the current replacement costs of similar assets adjusted for estimated depreciation and deterioration of the existing equipment and economic obsolescence. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of our impairment analysis will prove to be an accurate prediction of the future. The fair value measurements for the asset group fair values represent Level 3 measurements.

12. Goodwill and Intangibles

Goodwill

MPLX annually evaluates goodwill for impairment as of November 30, as well as whenever events or changes in circumstances indicate it is more likely than not that the fair value of a reporting unit with goodwill is less than its carrying amount.

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There were no events or changes in circumstances noted in the second quarter of 2020 which would indicate it is more likely than not that the fair value of our reporting units with goodwill is less than their carrying amount. During the first quarter of 2020, we determined that an interim impairment analysis of the goodwill recorded was necessary based on consideration of a number of first quarter events and circumstances as discussed in Note 1. Our producer customers in our Eastern G&P region reduced production forecasts and drilling activity in response to the global economic downturn. Additionally, a decline in NGL prices impacted our future revenue forecast. After performing our evaluations related to the interim impairment of goodwill during the first quarter of 2020, we recorded an impairment of $1,814 million within the Eastern G&P reporting unit, which was recorded to “Impairment expense” on the Consolidated Statements of Income. The impairment was primarily driven by additional guidance related to the slowing of drilling activity, which has reduced production growth forecasts from our producer customers. This resulted in goodwill totaling approximately $7.7 billion as of March 31, 2020 within four reporting units. The fair value of the remaining reporting units with goodwill were in excess of their carrying value by percentages ranging from 8.5 percent to 270.0 percent. The reporting unit whose fair value exceeded its carrying amount by 8.5 percent, our Crude Gathering reporting unit, had goodwill totaling $1.1 billion at March 31, 2020. The operations which make up this reporting unit were acquired through the merger with ANDX. MPC accounted for its October 1, 2018 acquisition of Andeavor (including acquiring control of ANDX), using the acquisition method of accounting, which required Andeavor assets and liabilities to be recorded by MPC at the acquisition date fair value. The Merger was closed on July 30, 2019 and has been treated as a common control transaction, which required the recognition of assets acquired and liabilities assumed using MPC’s historical carrying value. As such, given the short amount of time from when fair value was established to the date of the impairment test, the amount by which the fair value exceeded the carrying value within this reporting unit was not unexpected.

Our reporting units are one level below our operating segments and are determined based on the way in which segment management operates and reviews each operating segment. The fair value of our six reporting units was determined based on applying both a discounted cash flow or income approach as well as a market approach. The discounted cash flow fair value estimate is based on known or knowable information at the measurement date. The significant assumptions that were used to develop the estimates of the fair values under the discounted cash flow method included management’s best estimates of the expected future results and discount rate, which ranged from 9.5 percent to 11.5 percent. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the interim goodwill impairment test will prove to be an accurate prediction of the future. The fair value measurements for the individual reporting units represent Level 3 measurements.

After performing our evaluations related to the impairment of goodwill during the fiscal year ending December 31, 2019, we recorded an impairment of $1,197 million within the Western G&P reporting unit. The remainder of the reporting units’ fair values were in excess of their carrying values. The impairment was primarily driven by updated guidance related to the slowing of drilling activity, which has reduced production growth forecasts from our producer customers. This resulted in goodwill totaling approximately $9.5 billion as of December 31, 2019, with all but one of our six reporting units having goodwill.

The changes in carrying amount of goodwill were as follows:

(In millions)	L&S		G&P			Total
Gross goodwill as of December 31, 2018	$	7,234	$	2,912		$	10,146
Accumulated impairment losses	—		(130		)	(130		)
Balance as of December 31, 2018	7,234		2,782			10,016
Impairment losses	—		(1,197		)	(1,197		)
Acquisitions	488		229			717
Balance as of December 31, 2019	7,722		1,814			9,536
Impairment losses	—		(1,814		)	(1,814		)
Balance as of June 30, 2020	7,722		—			7,722
Gross goodwill as of June 30, 2020	7,722		3,141			10,863
Accumulated impairment losses	—		(3,141		)	(3,141		)
Balance as of June 30, 2020	$	7,722	$	—		$	7,722

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Intangible Assets

During the first quarter of 2020, we also determined that an impairment analysis of intangibles within our Western G&P reporting unit was necessary. See Note 11 for additional information regarding our assessment around the Western G&P reporting unit, and more specifically our East Texas G&P asset group. The fair value of the intangibles in our East Texas G&P asset group was determined based on applying the multi-period excess earnings method, which is an income approach. Key assumptions included management’s best estimates of the expected future cash flows from existing customers, customer attrition rates and the discount rate. After performing our evaluations related to the impairment of intangible assets associated with our East Texas G&P asset group during the first quarter of 2020, we recorded an impairment of $177 million to “Impairment expense” on the Consolidated Statements of Income related to our customer relationships.

MPLX’s remaining intangible assets are comprised of customer contracts and relationships. Gross intangible assets with accumulated amortization as of June 30, 2020 and December 31, 2019 is shown below:

		June 30, 2020							December 31, 2019
(In millions)	Useful Life	Gross		Accumulated Amortization(1)(2)			Net		Gross		Accumulated Amortization			Net
L&S	6 - 8 years	$	283	$	(63	)	$	220	$	283	$	(45	)	$	238
G&P	6 - 25 years	1,288		(485		)	803		1,288		(256		)	1,032
		$	1,571	$	(548	)	$	1,023	$	1,571	$	(301	)	$	1,270

(1) Amortization expense attributable to the G&P and L&S segments for the six months ended June 30, 2020 was $52 million and $18 million, respectively.

(2) Impairment charge of $177 million is included within the G&P accumulated amortization.

Estimated future amortization expense related to the intangible assets at June 30, 2020 is as follows:

(In millions)
2020	$	64
2021	128
2022	128
2023	128
2024	124
Thereafter	451
Total	$	1,023

13. Fair Value Measurements

Fair Values – Recurring

Fair value measurements and disclosures relate primarily to MPLX’s derivative positions as discussed in Note 14. The following table presents the financial instruments carried at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 by fair value hierarchy level. MPLX has elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty.

	June 30, 2020					December 31, 2019
(In millions)	Assets		Liabilities			Assets		Liabilities
Significant unobservable inputs (Level 3)
Embedded derivatives in commodity contracts	$	—	$	(51	)	$	—	$	(60	)
Total carrying value on Consolidated Balance Sheets	$	—	$	(51	)	$	—	$	(60	)

Level 3 instruments include all NGL transactions and embedded derivatives in commodity contracts. The embedded derivative liability relates to a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.38 to $0.92 per gallon with a weighted average of $0.53 per gallon per the current term of the embedded derivative and (2) the probability of renewal of 100 percent for the first five-year term and

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second five-year term of the gas purchase commitment and related keep-whole processing agreement, respectively. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of June 30, 2020 or December 31, 2019.

Changes in Level 3 Fair Value Measurements

The following table is a reconciliation of the net beginning and ending balances recorded for net assets and liabilities classified as Level 3 in the fair value hierarchy.

	Three Months Ended June 30, 2020					Three Months Ended June 30, 2019
(In millions)	Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)			Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	—	$	(45	)	$	—	$	(65	)
Total (losses)/gains (realized and unrealized) included in earnings(1)	—		(7		)	—		(1		)
Settlements	—		1			—		1
Fair value at end of period	—		(51		)	—		(65		)
The amount of total (losses)/gains for the period included in earnings attributable to the change in unrealized gains/(losses) relating to liabilities still held at end of period	$	—	$	(6	)	$	—	$	(2	)

	Six Months Ended June 30, 2020					Six Months Ended June 30, 2019
(In millions)	Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)			Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	—	$	(60	)	$	—	$	(61	)
Total gains/(losses) (realized and unrealized) included in earnings(1)	—		7			—		(7		)
Settlements	—		2			—		3
Fair value at end of period	—		(51		)	—		(65		)
The amount of total gains/(losses) for the period included in earnings attributable to the change in unrealized gains/(losses) relating to liabilities still held at end of period	$	—	$	7		$	—	$	(5	)

(1) Gains and losses on commodity derivative contracts classified as Level 3 are recorded in “Product sales” on the Consolidated Statements of Income. Gains and losses on derivatives embedded in commodity contracts are recorded in “Purchased product costs” and “Cost of revenues” on the Consolidated Statements of Income.

Fair Values – Reported

MPLX’s primary financial instruments are cash and cash equivalents, receivables, receivables from related parties, lease receivables from related parties, accounts payable, payables to related parties and long-term debt. MPLX’s fair value assessment incorporates a variety of considerations, including (1) the duration of the instruments, (2) MPC’s investment-grade credit rating and (3) the historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. MPLX believes the carrying values of its current assets and liabilities approximate fair value. The recorded value of the amounts outstanding under the bank revolving credit facility, if any, approximates fair value due to the variable interest rate that approximates current market rates. Derivative instruments are recorded at fair value, based on available market information (see Note 14).

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The fair value of MPLX’s long-term debt is estimated based on recent market non-binding indicative quotes. The fair value of the SMR liability is estimated using a discounted cash flow approach based on the contractual cash flows and MPLX’s unsecured borrowing rate. The long-term debt and SMR liability fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of the long-term debt, excluding finance leases, and SMR liability:

	June 30, 2020				December 31, 2019
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-term debt	$	21,919	$	20,646	$	21,054	$	19,800
SMR liability	$	88	$	78	$	90	$	80

14. Derivative Financial Instruments

As of June 30, 2020, MPLX had no outstanding commodity contracts beyond the embedded derivative discussed below.

Embedded Derivative - MPLX has a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2022. The customer has the unilateral option to extend the agreement for two consecutive five-year terms through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending options have been aggregated into a single compound embedded derivative. The probability of the customer exercising its options is determined based on assumptions about the customer’s potential business strategy decision points that may exist at the time they would elect whether to renew the contract. The changes in fair value of this compound embedded derivative are based on the difference between the contractual and index pricing and the probability of the producer customer exercising its option to extend. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. As of June 30, 2020 and December 31, 2019, the estimated fair value of this contract was a liability of $51 million and $60 million, respectively.

Certain derivative positions are subject to master netting agreements, therefore, MPLX has elected to offset derivative assets and liabilities that are legally permissible to be offset. As of June 30, 2020 and December 31, 2019, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	June 30, 2020					December 31, 2019
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability			Asset		Liability
Commodity contracts(1)
Other current assets / Other current liabilities	$	—	$	(3	)	$	—	$	(5	)
Other noncurrent assets / Deferred credits and other liabilities	—		(48		)	—		(55		)
Total	$	—	$	(51	)	$	—	$	(60	)

(1) Includes embedded derivatives in commodity contracts as discussed above.

For further information regarding the fair value measurement of derivative instruments, including the effect of master netting arrangements or collateral, see Note 13. There were no material changes to MPLX’s policy regarding the accounting for Level 2 and Level 3 instruments as previously disclosed in MPLX’s Annual Report on Form 10-K for the year ended December 31, 2019. MPLX does not designate any of its commodity derivative positions as hedges for accounting purposes.

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The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019			2020			2019
Purchased product costs
Realized (loss)/gain	$	(1	)	$	(1	)	$	(2	)	$	(3	)
Unrealized (loss)/gain	(6		)	—			9			(4		)
Purchased product costs derivative (loss)/gain	(7		)	(1		)	7			(7		)
Total derivative (loss)/gain	$	(7	)	$	(1	)	$	7		$	(7	)

15. Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	June 30, 2020			December 31, 2019
MPLX LP:
Bank revolving credit facility	$	825		$	—
Term loan facility	1,000			1,000
Floating rate senior notes	2,000			2,000
Fixed rate senior notes	16,887			16,887
Consolidated subsidiaries:
MarkWest	23			23
ANDX	190			190
Financing lease obligations(1)	13			19
Total	20,938			20,119
Unamortized debt issuance costs	(100		)	(106		)
Unamortized discount/premium	(279		)	(300		)
Amounts due within one year	(3		)	(9		)
Total long-term debt due after one year	$	20,556		$	19,704

(1)    See Note 20 for lease information.

Credit Agreement

Effective July 30, 2019, in connection with the closing of the Merger, MPLX amended and restated its existing revolving credit facility (the “MPLX Credit Agreement”) to, among other things, increase borrowing capacity to up to $3.5 billion and extend its term from July 2022 to July 2024. During the six months ended June 30, 2020, MPLX borrowed $2.5 billion under the MPLX Credit Agreement, at an average interest rate of 1.525 percent, and repaid $1.675 billion. At June 30, 2020, MPLX had $825 million in outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of $2.675 billion, or 76.4 percent of the borrowing capacity.

Term Loan Agreement

On September 26, 2019, MPLX entered into a Term Loan Agreement which provides for a committed term loan facility for up to an aggregate of $1 billion. Borrowings under the Term Loan Agreement bear interest, at MPLX’s election, at either (i) the Adjusted LIBO Rate (as defined in the Term Loan Agreement) plus a margin ranging from 75.0 basis points to 100.0 basis points per annum, depending on MPLX’s credit ratings, or (ii) the Alternate Base Rate (as defined in the Term Loan Agreement). Amounts borrowed under the Term Loan Agreement will be due and payable on September 26, 2021. As of June 30, 2020, MPLX had $1.0 billion outstanding on the term loan at an average interest rate of 1.665 percent.

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Floating Rate Senior Notes

On September 9, 2019, MPLX issued $2.0 billion aggregate principal amount of floating rate senior notes in a public offering, consisting of $1.0 billion aggregate principal amount of notes due September 2021 and $1.0 billion aggregate principal amount of notes due September 2022 (collectively, the “Floating Rate Senior Notes”). The Floating Rate Senior Notes were offered at a price to the public of 100 percent of par. The Floating Rate Senior Notes are callable, in whole or in part, at par plus accrued and unpaid interest at any time on or after September 10, 2020. Interest on the Floating Rate Senior Notes is payable quarterly in March, June, September and December, commencing on December 9, 2019. The interest rate applicable to the floating rate senior notes due September 2021 is LIBOR plus 0.9 percent per annum. The interest rate applicable to the floating rate senior notes due September 2022 is LIBOR plus 1.1 percent per annum.

Fixed Rate Senior Notes

MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes expiring between 2022 and 2058 with interest rates ranging from 3.375 percent to 6.375 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.

16. Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three and six months ended June 30, 2020 and 2019:

	Three Months Ended June 30, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	77	$	486	$	563
Service revenue - related parties	854		3		857
Service revenue - product related	—		22		22
Product sales	17		103		120
Product sales - related parties	4		26		30
Total revenues from contracts with customers	$	952	$	640	1,592
Non-ASC 606 revenue(1)					489
Total revenues and other income					$	2,081

	Three Months Ended June 30, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	79	$	540	$	619
Service revenue - related parties	843		4		847
Service revenue - product related	—		26		26
Product sales	15		174		189
Product sales - related parties	5		31		36
Total revenues from contracts with customers	$	942	$	775	1,717
Non-ASC 606 revenue(1)					493
Total revenues and other income					$	2,210

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	Six Months Ended June 30, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	161	$	1,014	$	1,175
Service revenue - related parties	1,774		11		1,785
Service revenue - product related	—		61		61
Product sales	32		257		289
Product sales - related parties	8		55		63
Total revenues from contracts with customers	$	1,975	$	1,398	3,373
Non-ASC 606 loss(1)					(300		)
Total revenues and other income					$	3,073

	Six Months Ended June 30, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	165	$	1,068	$	1,233
Service revenue - related parties	1,646		4		1,650
Service revenue - product related	—		60		60
Product sales	26		379		405
Product sales - related parties	9		68		77
Total revenues from contracts with customers	$	1,846	$	1,579	3,425
Non-ASC 606 revenue(1)					1,020
Total revenues and other income					$	4,445

(1) Non-ASC 606 Revenue includes rental income, income/(loss) from equity method investments, derivative gains and losses, mark-to-market adjustments, and other income.

(2) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

Contract Balances

Contract assets typically relate to aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer or for deficiency payments associated with minimum volume commitments which have not been billed to customers. Contract assets are generally classified as current and included in “Other current assets” on the Consolidated Balance Sheets.

Contract liabilities, which we refer to as “Deferred revenue” and “Long-term deferred revenue,” typically relate to advance payments for aid in construction agreements and deferred customer credits associated with makeup rights and minimum volume commitments. Related to minimum volume commitments, breakage is estimated and recognized into service revenue in instances where it is probable the customer will not use the credit in future periods. We classify contract liabilities as current or long-term based on the timing of when we expect to recognize revenue.

“Receivables, net” primarily relate to our commodity sales. Portions of the “Receivables, net” balance are attributed to the sale of commodity product controlled by MPLX prior to sale while a significant portion of the balance relates to the sale of commodity product on behalf of our producer customers. Both types of transactions are commingled and excluded from the table below. MPLX remits the net sales price back to our producer customers upon completion of the sale. Each period end, certain amounts within accounts payable relate to our payments to producer customers. Such amounts are not deemed material at period end as a result of when we settle with each producer.

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The tables below reflect the changes in our contract balances for the six-month periods ended June 30, 2020 and 2019:

(In millions)	Balance at December 31, 2019(1)		Additions/ (Deletions)			Revenue Recognized(2)			Balance at June 30, 2020
Contract assets	$	39	$	(20	)	$	(1	)	$	18
Deferred revenue	23		8			(5		)	26
Deferred revenue - related parties	53		48			(29		)	72
Long-term deferred revenue	90		11			—			101
Long-term deferred revenue - related parties	$	55	$	(2	)	$	—		$	53

(In millions)	Balance at December 31, 2018(1)		Additions/ (Deletions)(3)			Revenue Recognized(2)(3)			Balance at June 30, 2019(3)
Contract assets	$	36	$	(8	)	$	(1	)	$	27
Deferred revenue	13		4			(3		)	14
Deferred revenue - related parties	65		18			(30		)	53
Long-term deferred revenue	56		14			—			70
Long-term deferred revenue - related parties	$	52	$	(2	)	$	—		$	50

(1) Balance represents ASC 606 portion of each respective line item.

(2) No significant revenue was recognized related to past performance obligations in the current periods.

(3) Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

Remaining Performance Obligations

The table below includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period.

As of June 30, 2020, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $250 million and are reflected in the amounts below. This will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 31 years. Further, MPLX does not disclose variable consideration due to volume variability in the table below.

(In millions)
2020	$	938
2021	1,790
2022	1,759
2023	1,673
2024 and thereafter	5,915
Total revenue on remaining performance obligations(1),(2),(3)	$	12,075

(1) All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

(2) Arrangements deemed implicit leases are included in “Rental income” and are excluded from this table.

(3) Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

We do not disclose information on the future performance obligations for any contract with an original expected duration of

one year or less.

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17. Supplemental Cash Flow Information

	Six Months Ended June 30,
(In millions)	2020			2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	423		$	402
Income taxes paid	1			—
Non-cash investing and financing activities:
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	$	(1	)	$	1

The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that did not affect cash. The following is the change of additions to property, plant and equipment related to capital accruals:

	Six Months Ended June 30,
(In millions)	2020			2019
(Decrease)/increase in capital accruals	$	(172	)	$	(77	)

18. Accumulated Other Comprehensive Loss

MPLX LP records an accumulated other comprehensive loss on the Consolidated Balance Sheets relating to pension and other post-retirement benefits provided by LOOP LLC (“LOOP”) and Explorer Pipeline Company (“Explorer”) to their employees. MPLX LP is not a sponsor of these benefit plans.

The following table shows the changes in “Accumulated other comprehensive loss” by component during the period December 31, 2019 through June 30, 2020.

(In millions)	Pension Benefits			Other Post-Retirement Benefits			Total
Balance at December 31, 2019(1)	$	(14	)	$	(1	)	$	(15	)
Other comprehensive loss - remeasurements(2)	—			(1		)	(1		)
Balance at June 30, 2020(1)	$	(14	)	$	(2	)	$	(16	)

The following table shows the changes in “Accumulated other comprehensive loss” by component during the period December 31, 2018 through June 30, 2019.

(In millions)	Pension Benefits			Other Post-Retirement Benefits			Total
Balance at December 31, 2018(1)	$	(14	)	$	(2	)	$	(16	)
Other comprehensive income - remeasurements(2)	—			1			1
Balance at June 30, 2019(1)	$	(14	)	$	(1	)	$	(15	)

(1) These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”

(2) Components of other comprehensive income/loss - remeasurements relate to actuarial gains and losses as well as amortization of prior service costs. MPLX records an adjustment to “Comprehensive income” in accordance with its ownership interest in LOOP and Explorer.

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19. Equity-Based Compensation

Phantom Units

The following is a summary of phantom unit award activity of MPLX LP common units for the six months ended June 30, 2020:

	Number of Units		Weighted Average Fair Value
Outstanding at December 31, 2019	1,109,568		$	35.97
Granted	195,461		19.43
Settled	(323,884	)	35.67
Forfeited	(4,627	)	36.40
Outstanding at June 30, 2020	976,518		$	32.76

Performance Units – MPLX grants performance units to certain officers of the general partner and certain eligible MPC officers who make significant contributions to its business. These performance units pay out 75 percent in cash and 25 percent in MPLX LP common units and often contain both market and performance conditions based on various metrics. Market conditions are valued using a Monte Carlo valuation while performance conditions are reevaluated periodically and valued at the compensation cost associated with the performance outcome deemed most probable. 

The performance units granted in 2020 are hybrid awards having a three-year performance period of January 1, 2020 through December 31, 2022. The payout of the award is dependent on two independent conditions, each constituting 50 percent of the overall target units granted. The awards have a performance condition based on MPLX LP’s distributable cash flow, and a market condition based on MPLX LP’s total unitholder return. The market condition was valued using a Monte Carlo valuation, resulting in a grant date fair value of $0.80 per unit for the 2020 equity-classified performance units. Grant date fair value of the performance condition is based on potential payouts per unit of up to $2.00 per unit. Compensation cost associated with the performance condition is based on the grant date fair value of the payout deemed most probable to occur and is adjusted as the expectation for payout changes.

During the first quarter of 2018, a performance award was granted; however, due to the nature of the award terms, the grant date for this award was not established until the first quarter of 2020 and we began recognizing units and expense related to this award at that time. The performance units granted in 2018 are hybrid awards having a three-year performance period of January 1, 2018 through December 31, 2020. The payout of the award is dependent on two independent conditions, each constituting 50 percent of the overall target units granted. The awards have a performance condition based on an average of MPLX LP’s distributable cash flow and a market condition based on MPLX LP’s total unitholder return. The market condition was valued using a Monte Carlo valuation, resulting in a grant date fair value of $0.45 per unit for the 2018 equity-classified performance units. Grant date fair value of the performance condition is based on potential payouts per unit of up to $2.00 per unit. Compensation cost associated with the performance condition is based on the grant date fair value of the payout deemed most probable to occur and is adjusted as the expectation for payout changes.

The following is a summary of the activity for performance unit awards to be settled in MPLX LP common units for the six months ended June 30, 2020:

	Number of Units
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	(1,169,354	)
Forfeited	(31,668	)
Outstanding at June 30, 2020	3,103,536

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20. Leases

During the first quarter of 2020, reimbursements for projects at certain MPLX refining logistics locations were agreed to between MPLX and MPC. These reimbursements relate to the storage services agreements between MPLX and MPC at these locations and required the embedded leases within these agreements to be reassessed under the leasing standard. As a result of the reassessment, one of our leases was reclassified from an operating lease to a sales-type lease. As a result, the underlying assets previously shown on the Consolidated Balance Sheets associated with the sales-type lease were derecognized and the net investment in the lease (i.e., the sum of the present value of the future lease payments and the unguaranteed residual value of the assets) was recorded as a lease receivable. See Note 5 for the location of lease receivables and unguaranteed residual assets on the Consolidated Balance Sheets. The difference between the net book value of the underlying assets and the net investment in the lease has been recorded as a Contribution from MPC in the Consolidated Statements of Equity given that the transaction related to refining logistics was a common control transaction. During the first quarter of 2020, MPLX derecognized approximately $171 million of property, plant and equipment, recorded a lease receivable of approximately $370 million, recorded an unguaranteed residual asset of approximately $10 million and a Contribution from MPC of $209 million.

Lease revenues included on the Consolidated Statements of Income were as follows:

	Three Months Ended June 30, 2020				Three Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	195	$	66	$	246	$	68
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

	Six Months Ended June 30, 2020				Six Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	381	$	129	$	525	$	133
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	76		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

(1) These amounts are presented net of executory costs.

(2) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

See Note 5 for additional information on where related party lease assets are recorded in the Consolidated Balance Sheets. Third party lease assets are less than $1 million as of June 30, 2020 and are included within the “Receivables, net” and “Other noncurrent assets” captions within the Consolidated Balance Sheets.

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The following is a schedule of future payments on the sales-type leases as of June 30, 2020:

(In millions)	Related Party
2020	$	78
2021	157
2022	157
2023	158
2024	158
2025 and thereafter	473
Total minimum future rentals	1,181
Less: present value discount	758
Lease receivable	$	423

21. Commitments and Contingencies

MPLX is the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which MPLX has not recorded an accrued liability, MPLX is unable to estimate a range of possible losses because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material.

Environmental Matters – MPLX is subject to federal, state and local laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for non-compliance.

At June 30, 2020 and December 31, 2019, accrued liabilities for remediation totaled $18 million and $19 million, respectively. However, it is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, which may be imposed. At June 30, 2020 and December 31, 2019, there were no balances with MPC for indemnification of environmental costs.

MPLX is involved in environmental enforcement matters arising in the ordinary course of business. While the outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these environmental matters will not, individually or collectively, have a material adverse effect on its consolidated results of operations, financial position or cash flows.

MPLX is also a party to a number of other lawsuits and other proceedings arising in the ordinary course of business. While the ultimate outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated results of operations, financial position or cash flows.

Guarantees – Over the years, MPLX has sold various assets in the normal course of its business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require MPLX to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. MPLX is typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based.

In connection with our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL, we have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, have agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system.

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In March 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits for the Bakken Pipeline system, to conduct a full environmental impact statement (“EIS”), and further requested briefing on whether an easement permit necessary for the operation of the Bakken Pipeline system should be vacated while the EIS is being prepared.

On July 6, 2020, the D.D.C. ordered vacatur of the easement permit during the pendency of an EIS and further ordered shut down of the pipeline by August 5, 2020. The D.D.C. denied a motion to stay that order. Dakota Access and the Army Corps are appealing the D.D.C.’s order to the U.S. Court of Appeals for the District of Columbia Circuit. On July 14, 2020, the Circuit Court issued an administrative stay while the court considers Dakota Access and the Army Corps’ emergency motion for stay pending appeal.

If the pipeline is temporarily shutdown pending completion of the EIS, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the 1% redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of June 30, 2020, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $230 million.

Other Legal Proceedings – In early July, MPLX received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification covers the rights of way for 23 tracts of land and demands the immediate cessation of pipeline operations. The notification also assesses trespass damages of approximately $187 million. MPLX expects to receive a notification for an additional 11 tracts in the near future. We appealed this determination, which triggered an automatic stay of the requested pipeline shutdown and payment. We believe the trespass damage calculation is dependent on a novel interpretation of the applicable law, and we continue to actively negotiate settlement of this matter with holders of the property rights at issue. Management does not believe the ultimate resolution of this matter will have a material adverse effect on our consolidated financial position, results of operations, or cash flows.

Contractual Commitments and Contingencies – At June 30, 2020, MPLX’s contractual commitments to acquire property, plant and equipment totaled $293 million. These commitments were primarily related to G&P plant expansion, terminal and pipeline projects. In addition, from time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of June 30, 2020, management does not believe there are any indications that MPLX will not be able to meet the construction milestones, that force majeure does not apply or that such fees and charges will otherwise be triggered.

22. Subsequent Events

On July 31, 2020, MPLX entered into a Redemption Agreement (the “Redemption Agreement”) with Western Refining Southwest, Inc., an Arizona corporation (“WRSW”) and wholly owned subsidiary of MPC, pursuant to which MPLX agreed to transfer to WRSW all of the outstanding membership interests in Western Refining Wholesale, LLC, a Delaware limited liability company (“WRW”) to WRSW in exchange for the redemption of MPLX common units held by WRSW. The transaction effects the transfer to MPC of the Western wholesale distribution business that MPLX acquired as a result of its acquisition of ANDX. The Redemption Agreement was approved by the conflicts committee and the board of directors of MPLX’s general partner. The conflicts committee, which is composed of independent members of the board of directors of MPLX’s general partner, retained independent legal and financial advisors to assist it in evaluating and negotiating the transaction.

Per the terms of Redemption Agreement, MPLX redeemed 18,582,088 Common Units (the “Redeemed Units”) held by WRSW on July 31, 2020. The number of Redeemed Units was calculated by dividing WRW’s aggregate valuation of $340 million by the simple average of the volume weighted average New York Stock Exchange prices of an MPLX Common Unit for the ten trading days ending at market close on July 27, 2020.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Management’s Discussion and Analysis of Financial Condition and Results of Operations should also be read in conjunction with the unaudited consolidated financial statements and accompanying footnotes included under Item 1. Financial Statements and in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2019.

Disclosures Regarding Forward-Looking Statements

This Quarterly Report on Form 10-Q, particularly Management’s Discussion and Analysis of Financial Condition and Results of Operations and Quantitative and Qualitative Disclosures about Market Risk, includes forward-looking statements that are subject to risks, contingencies or uncertainties. You can identify forward-looking statements by words such as “anticipate,” “believe,” “commitment,” “could,” “design,” “estimate,” “expect,” “forecast,” “goal,” “guidance,” “imply,” “intend,” “may,” “objective,” “opportunity,” “outlook,” “plan,” “policy,” “position,” “potential,” “predict,” “priority,” “project,” “proposition,” “prospective,” “pursue,” “seek,” “should,” “strategy,” “target,” “will,” “would” or other similar expressions that convey the uncertainty of future events or outcomes.

Forward-looking statements include, among other things, statements regarding:

• future levels of revenues and other income, income from operations, net income attributable to MPLX LP, earnings per unit, Adjusted EBITDA or DCF (see the Non-GAAP Financial Information section below for the definitions of Adjusted EBITDA and DCF);

• future levels of capital, environmental or maintenance expenditures, general and administrative and other expenses;

• the success or timing of completion of ongoing or anticipated capital or maintenance projects;

• the amount and timing of future distributions; and

• the anticipated effects of actions of third parties such as competitors, activist investors or federal, foreign, state or local regulatory authorities or plaintiffs in litigation.

Our forward-looking statements are not guarantees of future performance and you should not rely unduly on them, as they involve risks, uncertainties and assumptions that we cannot predict. Material differences between actual results and any future performance suggested in our forward-looking statements could result from a variety of factors, including the following:

• the effects of the outbreak of COVID-19 and the adverse impact thereof on our business, financial condition, results of operations and cash flows, including our growth, operating costs, labor availability, logistical capabilities, customer demand for our services and industry demand generally, cash position, taxes, the price of our securities and trading markets with respect thereto, our ability to access capital markets, and the global economy and financial markets generally;

• Marathon Petroleum Corporation’s (“MPC”) ability to achieve its strategic objectives and the effects of those strategic decisions on us;

• the risk that anticipated opportunities and any other synergies from or anticipated benefits of the Andeavor Logistics LP (“ANDX”) acquisition may not be fully realized or may take longer to realize than expected, including whether the transaction will be accretive within the expected timeframe or at all;

• disruption from the ANDX acquisition making it more difficult to maintain relationships with customers, employees or suppliers;

• risks relating to any unforeseen liabilities of ANDX;

• further impairments;

• negative capital market conditions, including an increase of the current yield on common units;

• the ability to achieve strategic and financial objectives, including with respect to distribution coverage, future distribution levels, proposed projects and completed transactions;

• the success of MPC’s portfolio optimization, including the ability to complete any divestitures on commercially reasonable terms and/or within the expected timeframe, and the effects of any such divestitures on the business, financial condition, results of operations and cash flows;

• adverse changes in laws including with respect to tax and regulatory matters;

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• the adequacy of capital resources and liquidity, including the availability of sufficient cash flow to pay distributions and access to debt on commercially reasonable terms, and the ability to successfully execute business plans, growth strategies and self-funding models;

• the timing and extent of changes in commodity prices and demand for crude oil, refined products, feedstocks or other hydrocarbon-based products;

• volatility in or degradation of market and industry conditions as a result of the COVID-19 pandemic, other infectious disease outbreaks or otherwise;

• changes to the expected construction costs and timing of projects and planned investments, and the ability to obtain regulatory and other approvals with respect thereto;

• completion of midstream infrastructure by competitors;

• disruptions due to equipment interruption or failure, including electrical shortages and power grid failures;

• the suspension, reduction or termination of MPC’s obligations under MPLX’s commercial agreements;

• modifications to financial policies, capital budgets, and earnings and distributions;

• the ability to manage disruptions in credit markets or changes to credit ratings;

• compliance with federal and state environmental, economic, health and safety, energy and other policies and regulations or enforcement actions initiated thereunder;

• adverse results in litigation;

• the reliability of processing units and other equipment;

• the effect of restructuring or reorganization of business components;

• the potential effects of changes in tariff rates on our business, financial condition, results of operations and cash flows;

• foreign imports and exports of crude oil, refined products, natural gas and NGLs;

• changes in producer customers’ drilling plans or in volumes of throughput of crude oil, natural gas, NGLs, refined products or other hydrocarbon-based products;

• non-payment or non-performance by our producer and other customers;

• changes in the cost or availability of third-party vessels, pipelines, railcars and other means of transportation for crude oil, natural gas, NGLs, feedstocks and refined products;

• the price, availability and acceptance of alternative fuels and alternative-fuel vehicles and laws mandating such fuels or vehicles;

• actions taken by our competitors, including pricing adjustments and the expansion and retirement of pipeline capacity, processing, fractionation and treating facilities in response to market conditions;

• expectations regarding joint venture arrangements and other acquisitions or divestitures of assets;

• midstream and refining industry overcapacity or under capacity;

• accidents or other unscheduled shutdowns affecting our machinery, pipelines, processing, fractionation and treating facilities or equipment, or those of our suppliers or customers;

• acts of war, terrorism or civil unrest that could impair our ability to gather, process, fractionate or transport crude oil, natural gas, NGLs or refined products; and

• political pressure and influence of environmental groups upon policies and decisions related to the production, gathering, refining, processing, fractionation, transportation and marketing of crude oil or other feedstocks, refined products, natural gas, NGLs or other hydrocarbon-based products.

For additional risk factors affecting our business, see the risk factors described in our Annual Report on Form 10-K for the year ended December 31, 2019, as updated in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020. We undertake no obligation to update any forward-looking statements except to the extent required by applicable law.

MPLX OVERVIEW

We are a diversified, large-cap MLP formed by MPC, that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. We are engaged in the transportation, storage and distribution of crude oil and refined petroleum products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. Our operations are conducted in our Logistics and Storage and Gathering and Processing segments.

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SIGNIFICANT FINANCIAL AND OTHER HIGHLIGHTS

Significant financial highlights including revenues and other income, income from operations, net income, adjusted EBITDA attributable to MPLX and DCF attributable to GP and LP unitholders for the three months ended June 30, 2020 and June 30, 2019 are shown in the chart below. These results include the recast of ANDX financial information into MPLX’s financial information as a result of the Merger. See the Non-GAAP Financial Information section below for the definitions of Adjusted EBITDA and DCF and the Results of Operations section for further details regarding changes in these metrics.

(1) Q2 2019 includes Adjusted EBITDA attributable to Predecessor and portion of DCF adjustments attributable to Predecessor.

Other Highlights

RECENT DEVELOPMENTS

• On July 31, MPLX entered into a Redemption Agreement with WRSW, a wholly owned subsidiary of MPC, in which MPLX agreed to transfer the Western wholesale distribution business that it acquired as a result of its acquisition of ANDX to MPC in exchange for the redemption of $340 million of MPLX common units held by WRSW. The Redemption Agreement was approved by the MPLX board of directors following the approval of the terms of the transaction by its independent conflicts committee. The transaction closed on July 31.

• Announced a second quarter distribution rate of $0.6875 per common unit.

CURRENT ECONOMIC ENVIRONMENT

The outbreak of COVID-19 and its development into a pandemic in March 2020 has resulted in significant economic disruption globally. Actions taken by various governmental authorities, individuals and companies around the world to prevent the spread of COVID-19 through social distancing have restricted travel, many business operations, public gatherings and the overall level of individual movement and in-person interaction across the globe. This has significantly reduced global economic activity and resulted in a decline in the demand for products for which we provide midstream services. Macroeconomic conditions and global geopolitical events have also resulted in significant price volatility related to those aforementioned products.

We are actively responding to the impacts that these matters are having on our business by:

• Canceling or delaying certain capital expenditures that we had expected to make in 2020.

• Taking actions to reduce operating expenses across the business.

• Continuing to evaluate and high-grade our capital portfolio

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Many uncertainties remain with respect to COVID-19, including its resulting economic effects, and we are unable to predict the ultimate economic impacts from COVID-19 and how quickly national economies can recover once the pandemic ultimately subsides. However, the adverse impact will likely continue to have an impact on our business and our customers’ businesses. We believe we have proactively addressed many of the known impacts of COVID-19 to the extent possible and will strive to continue to do so, but there can be no guarantee the measures will be fully effective.

NON-GAAP FINANCIAL INFORMATION

Our management uses a variety of financial and operating metrics to analyze our performance. These metrics are significant factors in assessing our operating results and profitability and include the non-GAAP financial measures of Adjusted EBITDA and DCF. The amount of Adjusted EBITDA and DCF generated is considered by the board of directors of our general partner in approving MPLX’s cash distributions.

We define Adjusted EBITDA as net income adjusted for: (i) depreciation and amortization; (ii) provision/(benefit) for income taxes; (iii) amortization of deferred financing costs; (iv) extinguishment of debt; (v) non-cash equity-based compensation; (vi) impairment expense; (vii) net interest and other financial costs; (viii) income/(loss) from equity method investments; (ix) distributions and adjustments related to equity method investments; (x) unrealized derivative gains/(losses); (xi) acquisition costs; (xii) noncontrolling interest; and (xiii) other adjustments as deemed necessary. We also use DCF, which we define as Adjusted EBITDA adjusted for: (i) deferred revenue impacts; (ii) net interest and other financial costs; (iii) maintenance capital expenditures; (iv) equity method investment capital expenditures paid out; and (v) other non-cash items. MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

We believe that the presentation of Adjusted EBITDA and DCF provides useful information to investors in assessing our financial condition and results of operations. The GAAP measures most directly comparable to Adjusted EBITDA and DCF are net income and net cash provided by operating activities. Adjusted EBITDA and DCF should not be considered alternatives to GAAP net income or net cash provided by operating activities. Adjusted EBITDA and DCF have important limitations as analytical tools because they exclude some but not all items that affect net income and net cash provided by operating activities or any other measure of financial performance or liquidity presented in accordance with GAAP. Adjusted EBITDA and DCF should not be considered in isolation or as substitutes for analysis of our results as reported under GAAP. Additionally, because Adjusted EBITDA and DCF may be defined differently by other companies in our industry, our definitions of Adjusted EBITDA and DCF may not be comparable to similarly titled measures of other companies, thereby diminishing their utility. For a reconciliation of Adjusted EBITDA and DCF to their most directly comparable measures calculated and presented in accordance with GAAP, see Results of Operations.

Management also utilizes Segment Adjusted EBITDA in evaluating the financial performance of our segments. The use of this measures allows investors to understand how management evaluates financial performance to make operating decisions and allocate resources.

COMPARABILITY OF OUR FINANCIAL RESULTS

Our acquisitions have impacted comparability of our financial results (see Note 3 of the Notes to Consolidated Financial Statements).

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RESULTS OF OPERATIONS

The following tables and discussion are a summary of our results of operations for the three and six months ended June 30, 2020 and 2019, including a reconciliation of Adjusted EBITDA and DCF from “Net income” and “Net cash provided by operating activities,” the most directly comparable GAAP financial measures. Prior period financial information has been retrospectively adjusted for common control transactions.

	Three Months Ended June 30,								Six Months Ended June 30,
(In millions)	2020		2019			Variance			2020			2019			Variance
Total revenues and other income(1)	$	2,081	$	2,210		$	(129	)	$	3,073		$	4,445		$	(1,372	)
Costs and expenses:
Cost of revenues (excludes items below)	315		353			(38		)	683			692			(9		)
Purchased product costs	87		166			(79		)	222			360			(138		)
Rental cost of sales	33		29			4			68			66			2
Rental cost of sales - related parties	41		36			5			87			79			8
Purchases - related parties	280		313			(33		)	556			591			(35		)
Depreciation and amortization	321		313			8			646			614			32
Impairment expense	—		—			—			2,165			—			2,165
General and administrative expenses	96		90			6			193			191			2
Other taxes	30		25			5			61			55			6
Total costs and expenses	1,203		1,325			(122		)	4,681			2,648			2,033
Income/(loss) from operations	878		885			(7		)	(1,608		)	1,797			(3,405		)
Related party interest and other financial costs	1		2			(1		)	4			3			1
Interest expense, net of amounts capitalized	206		214			(8		)	417			428			(11		)
Other financial costs	16		13			3			32			22			10
Income/(loss) before income taxes	655		656			(1		)	(2,061		)	1,344			(3,405		)
(Benefit)/provision for income taxes	—		(1		)	1			—			(2		)	2
Net income/(loss)	655		657			(2		)	(2,061		)	1,346			(3,407		)
Less: Net income attributable to noncontrolling interests	7		6			1			15			12			3
Less: Net income attributable to Predecessor	—		169			(169		)	—			349			(349		)
Net income/(loss) attributable to MPLX LP	648		482			166			(2,076		)	985			(3,061		)
Adjusted EBITDA attributable to MPLX LP (excluding Predecessor results)(2)	1,227		920			307			2,521			1,850			671
Adjusted EBITDA attributable to MPLX LP (including Predecessor results)(3)	N/A		1,249			N/A			N/A			2,512			N/A
DCF attributable to GP and LP unitholders (including Predecessor results)(3)	$	996	$	975		$	21		$	2,043		$	1,966		$	77

(1) The six months ended June 30, 2020 includes impairment expense of approximately $1.3 billion related to three equity method investments.

(2) Non-GAAP measure. See reconciliation below to the most directly comparable GAAP measures. Excludes adjusted EBITDA and DCF adjustments attributable to Predecessor.

(3) Non-GAAP measure. See reconciliation below to the most directly comparable GAAP measures. Includes adjusted EBITDA and DCF adjustments attributable to Predecessor.

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	Three Months Ended June 30,									Six Months Ended June 30,
(In millions)	2020			2019			Variance			2020			2019			Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income:
Net income	$	655		$	657		$	(2	)	$	(2,061	)	$	1,346		$	(3,407	)
Provision for income taxes	—			(1		)	1			—			(2		)	2
Amortization of deferred financing costs	15			12			3			29			19			10
Net interest and other financial costs	208			217			(9		)	424			434			(10		)
Income from operations	878			885			(7		)	(1,608		)	1,797			(3,405		)
Depreciation and amortization	321			313			8			646			614			32
Non-cash equity-based compensation	3			5			(2		)	8			12			(4		)
Impairment expense	—			—			—			2,165			—			2,165
(Income)/loss from equity method investments	(89		)	(83		)	(6		)	1,095			(160		)	1,255
Distributions/adjustments related to equity method investments	115			132			(17		)	239			254			(15		)
Unrealized derivative losses/(gains)(1)	6			—			6			(9		)	4			(13		)
Acquisition costs	—			4			(4		)	—			5			(5		)
Other	1			—			1			2			—			2
Adjusted EBITDA	1,235			1,256			(21		)	2,538			2,526			12
Adjusted EBITDA attributable to noncontrolling interests	(8		)	(7		)	(1		)	(17		)	(14		)	(3		)
Adjusted EBITDA attributable to Predecessor(2)	—			(329		)	329			—			(662		)	662
Adjusted EBITDA attributable to MPLX LP(3)	1,227			920			307			2,521			1,850			671
Deferred revenue impacts	40			22			18			63			31			32
Net interest and other financial costs	(208		)	(217		)	9			(424		)	(434		)	10
Maintenance capital expenditures	(33		)	(62		)	29			(67		)	(99		)	32
Maintenance capital expenditures reimbursements	6			9			(3		)	20			16			4
Equity method investment capital expenditures paid out	(4		)	(4		)	—			(11		)	(8		)	(3		)
Other	(1		)	10			(11		)	3			10			(7		)
Portion of DCF adjustments attributable to Predecessor(2)	—			63			(63		)	—			132			(132		)
DCF	1,027			741			286			2,105			1,498			607
Preferred unit distributions	(31		)	(32		)	1			(62		)	(62		)	—
DCF attributable to GP and LP unitholders	996			709			287			2,043			1,436			607
Adjusted EBITDA attributable to Predecessor(2)	—			329			(329		)	—			662			(662		)
Portion of DCF adjustments attributable to Predecessor(2)	—			(63		)	63			—			(132		)	132
DCF attributable to GP and LP unitholders (including Predecessor results)	$	996		$	975		$	21		$	2,043		$	1,966		$	77

(1) MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

(2) The adjusted EBITDA and DCF adjustments related to Predecessor are excluded from adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders prior to the acquisition date.

(3) For the three months ended June 30, 2020, the L&S and G&P segments made up $839 million and $388 million of Adjusted EBITDA attributable to MPLX LP, respectively. For the three months ended June 30, 2019, the L&S and G&P segments made up $570 million and $350 million of Adjusted EBITDA attributable to MPLX LP, respectively. For the six months ended June 30, 2020, the L&S and G&P segments made up $1,711 million and $810

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million of Adjusted EBITDA attributable to MPLX LP, respectively. For the six months ended June 30, 2019, the L&S and G&P segments made up $1,129 million and $721 million of Adjusted EBITDA attributable to MPLX LP, respectively.

	Six Months Ended June 30,
(In millions)	2020			2019			Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net cash provided by operating activities:
Net cash provided by operating activities	$	2,114		$	1,954		$	160
Changes in working capital items	12			112			(100		)
All other, net	(26		)	(7		)	(19		)
Non-cash equity-based compensation	8			12			(4		)
Net (loss)/gain on disposal of assets	(1		)	2			(3		)
Net interest and other financial costs	424			434			(10		)
Current income taxes	1			—			1
Asset retirement expenditures	—			1			(1		)
Unrealized derivative (gains)/losses(1)	(9		)	4			(13		)
Acquisition costs	—			5			(5		)
Other adjustments to equity method investment distributions	13			9			4
Other	2			—			2
Adjusted EBITDA	2,538			2,526			12
Adjusted EBITDA attributable to noncontrolling interests	(17		)	(14		)	(3		)
Adjusted EBITDA attributable to Predecessor(2)	—			(662		)	662
Adjusted EBITDA attributable to MPLX LP(3)	2,521			1,850			671
Deferred revenue impacts	63			31			32
Net interest and other financial costs	(424		)	(434		)	10
Maintenance capital expenditures	(67		)	(99		)	32
Maintenance capital expenditures reimbursements	20			16			4
Equity method investment capital expenditures paid out	(11		)	(8		)	(3		)
Other	3			10			(7		)
Portion of DCF adjustments attributable to Predecessor(2)	—			132			(132		)
DCF	2,105			1,498			607
Preferred unit distributions	(62		)	(62		)	—
DCF attributable to GP and LP unitholders	2,043			1,436			607
Adjusted EBITDA attributable to Predecessor(2)	—			662			(662		)
Portion of DCF adjustments attributable to Predecessor(2)	—			(132		)	132
DCF attributable to GP and LP unitholders (including Predecessor results)	$	2,043		$	1,966		$	77

(1) MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

(2) The adjusted EBITDA and DCF adjustments related to Predecessor are excluded from adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders prior to the acquisition date.

(3) For the six months ended June 30, 2020, the L&S and G&P segments made up $1,711 million and $810 million of Adjusted EBITDA attributable to MPLX LP, respectively. For the six months ended June 30, 2019, the L&S and G&P segments made up $1,129 million and $721 million of Adjusted EBITDA attributable to MPLX LP, respectively.

Three months ended June 30, 2020 compared to three months ended June 30, 2019

Total revenues and other income decreased $129 million in the second quarter of 2020 compared to the same period of 2019. This decrease was primarily due to lower G&P fees from lower volumes of $46 million as well as an unfavorable impact from lower prices of $87 million. There were also decreases due to lower L&S pipeline, terminal and storage volumes, including decreased throughputs on our Explorer and Bakken pipeline equity method investments. These decreases were offset by favorable L&S rate impacts as well as increased volume deficiency payments, favorable impacts from increased marine

44

equipment and increased volumes in our Sherwood Midstream LLC joint venture due to additional plants coming online in the second half of 2019.

Cost of Revenues decreased $38 million in the second quarter of 2020 compared to the same period of 2019, primarily due to lower operating costs due to lower throughput, lower project-related spend and other miscellaneous expense decreases.

Purchased product costs decreased $79 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to lower prices of $49 million in the Southwest and Southern Appalachia and lower costs from lower volumes of $36 million in the Southwest. This was partially offset by an increase of $6 million in unrealized derivative losses from prior year.

Purchases - related parties decreased $33 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to lower project spend and product purchases from MPC.

Depreciation and amortization expense increased $8 million in the second quarter of 2020 compared to the same period of 2019, primarily due to property, plant and equipment placed in service in the second half of 2019 and the first six months of 2020.

Net interest expense and other financial costs decreased $6 million in the second quarter of 2020 compared to the same period of 2019 due to decreased interest on variable rate debt as a result of lower interest rates during the quarter.

General and administrative expenses increased $6 million in the second quarter of 2020 compared to the same period of 2019 primarily due to increased employee costs from MPC.

Six months ended June 30, 2020 compared to six months ended June 30, 2019

Total revenues and other income decreased $1,372 million in the first six months of 2020 compared to the same period of 2019. The large decrease was driven by our ownership in MarkWest Utica EMG, L.L.C. (“MarkWest Utica EMG”), our indirect ownership in Ohio Gathering Company, L.L.C. through our investment of MarkWest Utica EMG and our ownership in Uintah Basin Field Services, L.L.C., as we recognized impairments related to these investments in the first quarter of 2020 in the amount of $1,264 million. Also contributing to the decrease was lower G&P fees from lower volumes of $6 million and an unfavorable impact from lower prices of $171 million. There were also decreases due to lower L&S pipeline, terminal and storage volumes, including decreased throughputs on our Explorer and Bakken pipeline equity method investments. These decreases were offset by favorable L&S rate impacts as well as increased volume deficiency payments, favorable impacts from increased marine equipment and increased volumes in our Sherwood Midstream LLC joint venture due to additional plants coming online in the second half of 2019.

Cost of Revenues decreased $9 million in the first six months of 2020 compared to the same period of 2019, primarily due to lower project-related costs, which include repairs, maintenance and operating costs in the L&S and G&P segments.

Purchased product costs decreased $138 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to lower prices of $94 million in the Southwest and Southern Appalachia and $31 million from lower volumes in the Southwest. There was also a decrease of $13 million due to unrealized derivative gains in the current year compared to unrealized derivative losses in the prior year.

Rental cost of sales - related parties increased $8 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to project costs incurred, partially offset by lower operating costs due to reduced throughput.

Purchases - related parties decreased $35 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to lower product purchases from MPC, lower project spend and decreased other miscellaneous costs from

MPC.

Depreciation and amortization expense increased $32 million in the first six months of 2020 compared to the same period of 2019, primarily due to property, plant and equipment placed in service in the second half of 2019 and the first six months of 2020.

Impairment expense increased $2,165 million in the first six months of 2020 compared to the same period of 2019. During the first quarter of 2020 we recorded impairment expense for goodwill, intangible assets and property, plant and equipment of $1,814 million, $177 million and $174 million, respectively. The impairment of goodwill related to our Eastern G&P reporting

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unit while the intangible asset and property, plant and equipment impairments relate to certain assets in our Southwest region. The impairments were primarily driven by the slowing of drilling activity, which has reduced production growth forecasts from our producer customers.

Other taxes increased $6 million in the first six months of 2020 compared to the same period of 2019 primarily due to prior period refunds and credits.

SEGMENT RESULTS

We classify our business in the following reportable segments: L&S and G&P. Segment Adjusted EBITDA represents Adjusted EBITDA attributable to the reportable segments. Amounts included in net income and excluded from Segment Adjusted EBITDA include: (i) depreciation and amortization; (ii) provision/(benefit) for income taxes; (iii) amortization of deferred financing costs; (iv) extinguishment of debt; (v) non-cash equity-based compensation; (vi) impairment expense; (vii) net interest and other financial costs; (viii) income/(loss) from equity method investments; (ix) distributions and adjustments related to equity method investments; (x) unrealized derivative gains/(losses); (xi) acquisition costs; (xii) noncontrolling interests; and (xiii) other adjustments as deemed necessary. These items are either: (i) believed to be non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about Segment Adjusted EBITDA for the reported segments for the three and six months ended June 30, 2020 and 2019. Prior period financial information has been retrospectively adjusted for common control transactions.

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L&S Segment

(1) Includes adjusted EBITDA attributable to Predecessor.

	Three Months Ended June 30,									Six Months Ended June 30,
(In millions)	2020			2019			Variance			2020			2019			Variance
Service revenue	$	931		$	922		$	9		$	1,935		$	1,811		$	124
Rental income	246			296			(50		)	488			631			(143		)
Product related revenue	21			20			1			40			35			5
Income from equity method investments	40			54			(14		)	90			99			(9		)
Other income	52			16			36			103			28			75
Total segment revenues and other income	1,290			1,308			(18		)	2,656			2,604			52
Cost of revenues	190			219			(29		)	428			445			(17		)
Purchases - related parties	211			227			(16		)	410			417			(7		)
Depreciation and amortization	138			134			4			276			260			16
General and administrative expenses	52			42			10			104			93			11
Other taxes	18			11			7			34			27			7
Segment income from operations	681			675			6			1,404			1,362			42
Depreciation and amortization	138			134			4			276			260			16
Income from equity method investments	(40		)	(54		)	14			(90		)	(99		)	9
Distributions/adjustments related to equity method investments	57			60			(3		)	114			114			—
Acquisition costs	—			4			(4		)	—			5			(5		)
Non-cash equity-based compensation	2			2			—			5			7			(2		)
Other	1			—			1			2			—			2
Adjusted EBITDA attributable to Predecessor	—			(251		)	251			—			(520		)	520
Segment adjusted EBITDA(1)	839			570			269			1,711			1,129			582
Capital expenditures	108			230			(122		)	292			428			(136		)
Investments in unconsolidated affiliates	$	74		$	61		$	13		$	128		$	68		$	60

(1) See the Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income table for the reconciliation to the most directly comparable GAAP measure.

Three months ended June 30, 2020 compared to three months ended June 30, 2019

Service revenue increased $9 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to a $28 million increase due to the reclassification of lease income between service revenue, rental income and other income based on modifications to lease contracts and a $12 million increase from additional marine equipment. There was also in increase in volume deficiency payments, favorable price impacts and other miscellaneous items. These increases were partially offset by reduced pipeline and storage volumes.

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Rental income decreased $50 million in the second quarter of 2020 compared to the same period of 2019, primarily due to a decrease of $66 million due to the reclassification of lease income between service revenue, rental income and other income based on modifications to lease contracts. The decrease was partially offset by an increase of $7 million from increased terminal storage revenue as well as other miscellaneous increases.

Income from equity method investments decreased $14 million in the second quarter of 2020 compared to the same period of 2019, primarily due to decreased throughput on the Explorer and Bakken pipelines due to declining demand during the second quarter of 2020.

Other income increased $36 million in the second quarter of 2020 compared to the same period of 2019, primarily due to an increase of $38 million due to the reclassification of lease income between service revenue, rental income and other income based on modifications to lease contracts.

Cost of revenues decreased $29 million in the second quarter of 2020 compared to the same period of 2019, primarily due to lower operating costs due to lower throughput, lower project-related spend and other miscellaneous expense decreases.

Purchases - related parties decreased $16 million in the second quarter of 2020 compared to the same period of 2019, primarily due to lower project spend and other miscellaneous expenses.

General and administrative expenses increased $10 million in the second quarter of 2020 compared to the same period of 2019, primarily due to increased employee costs from MPC.

Six months ended June 30, 2020 compared to six months ended June 30, 2019

Service revenue increased $124 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to an $83 million increase due to the reclassification of lease income between service revenue, rental income and other income based on modifications to lease contracts and a $25 million increase from additional marine equipment. There were also increases related to volume deficiency payments and favorable price impacts partially offset by unfavorable volume impacts.

Rental income decreased $143 million in the first six months of 2020 compared to the same period of 2019, primarily due to a decrease of $159 million due to the reclassification of lease income between service revenue, rental income and other income based on modifications to lease contracts. The decrease was partially offset by an increase of $13 million from increased terminal storage revenue.

Income from equity method investments decreased $9 million in the first six months of 2020 compared to the same period of 2019, primarily due to decreased throughput on the Explorer and Bakken pipelines due to declining demand during the second quarter of 2020.

Other income increased $75 million in the first six months of 2020 compared to the same period of 2019, primarily due to an increase of $76 million due to the reclassification of lease income between service revenue, rental income and other income based on modifications to lease contracts.

Cost of revenues decreased $17 million in the first six months of 2020 compared to the same period of 2019, primarily due to lower operating costs due to lower throughput, lower project-related spend and other miscellaneous expense decreases.

Purchases - related parties decreased $7 million in the first six months of 2020 compared to the same period of 2019, primarily due to lower project spend and other miscellaneous expenses.

Depreciation and amortization increased $16 million in the first six months of 2020 compared to the same period of 2019, primarily due to property, plant and equipment placed in service in the second half of 2019 and the first six months of 2020.

General and administrative expenses increased $11 million in the first six months of 2020 compared to the same period of 2019, primarily due to increased employee costs from MPC.

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G&P Segment

(1) Includes adjusted EBITDA attributable to Predecessor.

	Three Months Ended June 30,									Six Months Ended June 30,
(In millions)	2020			2019			Variance			2020			2019			Variance
Service revenue	$	489		$	544		$	(55	)	$	1,025		$	1,072		$	(47	)
Rental income	89			83			6			177			172			5
Product related revenue	151			231			(80		)	373			507			(134		)
Income/(loss) from equity method investments	49			29			20			(1,185		)	61			(1,246		)
Other income	13			15			(2		)	27			29			(2		)
Total segment revenues and other income/(loss)	791			902			(111		)	417			1,841			(1,424		)
Cost of revenues	199			199			—			410			392			18
Purchased product costs	87			166			(79		)	222			360			(138		)
Purchases - related parties	69			86			(17		)	146			174			(28		)
Depreciation and amortization	183			179			4			370			354			16
Impairment expense	—			—			—			2,165			—			2,165
General and administrative expenses	44			48			(4		)	89			98			(9		)
Other taxes	12			14			(2		)	27			28			(1		)
Segment income/(loss) from operations	197			210			(13		)	(3,012		)	435			(3,447		)
Depreciation and amortization	183			179			4			370			354			16
Impairment expense	—			—			—			2,165			—			2,165
(Income)/loss from equity method investments	(49		)	(29		)	(20		)	1,185			(61		)	1,246
Distributions/adjustments related to equity method investments	58			72			(14		)	125			140			(15		)
Unrealized derivative losses/(gains)(1)	6			—			6			(9		)	4			(13		)
Non-cash equity-based compensation	1			3			(2		)	3			5			(2		)
Adjusted EBITDA attributable to Predecessor	—			(78		)	78			—			(142		)	142
Adjusted EBITDA attributable to noncontrolling interests	(8		)	(7		)	(1		)	(17		)	(14		)	(3		)
Segment Adjusted EBITDA(2)	388			350			38			810			721			89
Capital expenditures	110			326			(216		)	244			632			(388		)
Investments in unconsolidated affiliates	$	57		$	127		$	(70	)	$	94		$	255		$	(161	)

(1) MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

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(2) See the Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income table for the reconciliation to the most directly comparable GAAP measure.

Three months ended June 30, 2020 compared to three months ended June 30, 2019

Service revenue decreased $55 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to lower fees from lower volumes in the Southwest, Bakken and Rockies of $38 million, a decrease due to lower prices in the Bakken of $2 million as well as other miscellaneous decreases.

Rental income increased $6 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to higher rental income from higher volumes in the Marcellus.

Product related revenue decreased $80 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to lower prices in all of the G&P regions of approximately $85 million and lower volumes in the Southwest of $34 million. This was partially offset by $20 million of volume increases in the Marcellus, Rockies and at our Javelina plant in the Southwest (this plant experienced downtime for maintenance in 2019), as well as other miscellaneous increases.

Income from equity method investments increased $20 million in the second quarter of 2020 compared to the same period of 2019. This increase was due to lower basis differential amortization related to MarkWest Utica EMG as a result of impairments recorded in the first quarter of 2020 and an increase from the Sherwood Midstream LLC joint venture due to additional plants coming online during the second half of 2019.

Purchased product costs decreased $79 million in the second quarter of 2020 compared to the same period of 2019. This was primarily due to lower prices of $49 million in the Southwest and Southern Appalachia and lower costs from lower volumes of $36 million in the Southwest. This was partially offset by an increase of $6 million in unrealized derivative losses from prior year.

Purchases - related parties decreased $17 million in the second quarter of 2020 compared to the same period of 2019, with this decrease primarily being attributable to aligning various expenses as a result of the ANDX acquisition and lower product purchases from MPC.

Six months ended June 30, 2020 compared to six months ended June 30, 2019

Service revenue decreased $47 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to lower fees from lower volumes in the Rockies of $19 million and lower prices in the Bakken of $3 million as well as other miscellaneous decreases.

Rental income increased $5 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to fees from higher volumes in the Marcellus.

Product related revenue decreased $134 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to lower prices in all of the G&P regions of approximately $168 million and lower volumes of $21 million in the Southwest. This was partially offset by $21 million of volume increases in the Rockies and the Javelina plant in the Southwest (this plant experienced downtime for maintenance in 2019), as well as other miscellaneous increases.

Income from equity method investments decreased $1,246 million in the first six months of 2020 compared to the same period of 2019. The large decrease was driven by our ownership in MarkWest Utica EMG, our indirect ownership in Ohio Gathering Company, L.L.C. through our investment of MarkWest Utica EMG and our ownership in Uintah Basin Field Services, L.L.C., as we recognized impairments related to these investments in the first quarter of 2020 in the amount of $1,264 million. This was partially offset by an increase in the Sherwood Midstream LLC joint venture due to additional plants coming online during the second half of 2019.

Cost of revenues increased $18 million in the first six months of 2020 compared to the same period of 2019. The majority of the increase is attributable to aligning various expenses as a result of the ANDX acquisition as well as higher repairs, maintenance and operating costs in the Marcellus offset by lower repairs, maintenance and operating costs in the Southwest, Southern Appalachia and Rockies.

Purchased product costs decreased $138 million in the first six months of 2020 compared to the same period of 2019. This was primarily due to lower prices of $94 million in the Southwest and Southern Appalachia and $31 million from lower volumes in

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the Southwest. There was also a decrease of $13 million due to unrealized derivative gains in the current year compared to unrealized derivative losses in the prior year.

Purchases - related parties decreased $28 million in the first six months of 2020 compared to the same period of 2019. This decrease is primarily attributable to aligning various expenses as a result of the ANDX acquisition and lower product purchases from MPC.

Depreciation and amortization increased $16 million in the first six months of 2020 compared to the same period of 2019 primarily due to property, plant and equipment placed in service throughout the second half of 2019 and the first six months of 2020.

Impairment expense increased $2,165 million in the first six months of 2020 compared to the same period of 2019. During the first quarter of 2020 we recorded impairment expense for goodwill, intangible assets and property, plant and equipment of $1,814 million, $177 million and $174 million, respectively. The impairment of goodwill related to our Eastern G&P reporting unit while the intangible asset and property, plant and equipment impairments relate to certain assets in our Southwest region. The impairments were primarily driven by the slowing of drilling activity, which has reduced production growth forecasts from our producer customers.

General and administrative expenses decreased $9 million in the first six months of 2020 compared to the same period of 2019 due to lower employee related costs.

SEASONALITY

The volume of crude oil and refined products transported and stored utilizing our assets is directly affected by the level of supply and demand for crude oil and refined products in the markets served directly or indirectly by our assets. Many effects of seasonality on the L&S segment’s revenues will be mitigated through the use of our fee-based transportation and storage services agreements with MPC that include minimum volume commitments.

Our G&P segment can be affected by seasonal fluctuations in the demand for natural gas and NGLs and the related fluctuations in commodity prices caused by various factors including variations in weather patterns from year to year. We are able to manage the seasonality impacts through the execution of our marketing strategy and via our storage capabilities. Overall, our exposure to the seasonality fluctuations is declining due to our growth in fee-based business.

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OPERATING DATA⁽¹⁾

	Three Months Ended   June 30,				Six Months Ended   June 30,
	2020		2019		2020		2019
L&S
Pipeline throughput (mbpd)
Crude oil pipelines	2,733		3,242		2,971		3,174
Product pipelines	1,586		1,867		1,746		1,882
Total pipelines	4,319		5,109		4,717		5,056
Average tariff rates ($ per barrel)(2)
Crude oil pipelines	$	0.99	$	0.88	$	0.96	$	0.92
Product pipelines	0.84		0.75		0.81		0.72
Total pipelines	$	0.94	$	0.83	$	0.90	$	0.84
Terminal throughput (mbpd)	2,420		3,287		2,693		3,253
Marine Assets (number in operation)(3)
Barges	305		261		305		261
Towboats	23		23		23		23

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	Three Months Ended   June 30, 2020		Three Months Ended   June 30, 2019
	MPLX LP(4)	MPLX LP Operated(5)	MPLX LP(4)	MPLX LP Operated(5)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,385	1,385	1,266	1,266
Utica Operations	—	1,903	—	2,066
Southwest Operations	1,365	1,393	1,617	1,617
Bakken Operations	126	126	147	147
Rockies Operations	495	683	649	852
Total gathering throughput	3,371	5,490	3,679	5,948
Natural Gas Processed (MMcf/d)
Marcellus Operations	4,112	5,516	4,216	5,202
Utica Operations	—	585	—	823
Southwest Operations	1,412	1,510	1,558	1,558
Southern Appalachian Operations	223	223	243	243
Bakken Operations	126	126	147	147
Rockies Operations	516	516	585	585
Total natural gas processed	6,389	8,476	6,749	8,558
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(6)	464	464	440	440
Utica Operations(6)	—	31	—	40
Southwest Operations	13	13	3	3
Southern Appalachian Operations(7)	12	12	12	12
Bakken Operations	19	19	21	21
Rockies Operations	4	4	3	3
Total C2 + NGLs fractionated(8)	512	543	479	519

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	Six Months Ended   June 30, 2020		Six Months Ended   June 30, 2019
	MPLX LP(4)	MPLX LP Operated(5)	MPLX LP(4)	MPLX LP Operated(5)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,402	1,402	1,274	1,274
Utica Operations	—	1,852	—	2,087
Southwest Operations	1,461	1,497	1,600	1,600
Bakken Operations	141	141	150	150
Rockies Operations	544	729	644	839
Total gathering throughput	3,548	5,621	3,668	5,950
Natural Gas Processed (MMcf/d)
Marcellus Operations	4,155	5,519	4,185	5,175
Utica Operations	—	616	—	820
Southwest Operations	1,530	1,595	1,578	1,578
Southern Appalachian Operations	233	233	239	239
Bakken Operations	141	141	150	150
Rockies Operations	528	528	578	578
Total natural gas processed	6,587	8,632	6,730	8,540
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(6)	460	460	430	430
Utica Operations(6)	—	33	—	43
Southwest Operations	14	14	10	10
Southern Appalachian Operations(7)	12	12	12	12
Bakken Operations	25	25	18	18
Rockies Operations	4	4	4	4
Total C2 + NGLs fractionated(8)	515	548	474	517

	Three Months Ended   June 30,				Six Months Ended   June 30,
	2020		2019		2020		2019
Pricing Information
Natural Gas NYMEX HH ($ per MMBtu)	$	1.76	$	2.51	$	1.81	$	2.69
C2 + NGL Pricing ($ per gallon)(9)	$	0.34	$	0.52	$	0.37	$	0.57

(1) Operating data is inclusive of operating data for ANDX.

(2) Average tariff rates calculated using pipeline transportation revenues divided by pipeline throughput barrels.

(3) Represents total at end of period.

(4) This column represents operating data for entities that have been consolidated into the MPLX financial statements.

(5) This column represents operating data for entities that have been consolidated into the MPLX financial statements as well as operating data for MPLX-operated equity method investments.

(6) Hopedale is jointly owned by Ohio Fractionation and MarkWest Utica EMG. Ohio Fractionation is a subsidiary of MarkWest Liberty Midstream. MarkWest Liberty Midstream and MarkWest Utica EMG are entities that operate in the Marcellus and Utica regions, respectively. Marcellus Operations includes Ohio Fractionation’s portion utilized of the jointly owned Hopedale Fractionation Complex. Utica Operations includes MarkWest Utica EMG’s portion utilized of the jointly owned Hopedale Fractionation Complex. Additionally, Sherwood Midstream has the right to fractionation revenue and the obligation to pay expenses related to 40 mbpd of capacity in the Hopedale 3 and Hopedale 4 fractionators.

(7) Includes NGLs fractionated for the Marcellus Operations and Utica Operations.

(8) Purity ethane makes up approximately 193 mbpd and 195 mbpd of total MPLX Operated, fractionated products for the three months ended June 30, 2020 and 2019, respectively, and approximately 191 mbpd and 192 mbpd of total fractionated products for the six months ended June 30, 2020 and 2019, respectively. Purity ethane makes up approximately 186 mbpd and 189 mbpd of total MPLX LP consolidated, fractionated products for the three months ended June 30, 2020 and 2019, respectively, and approximately 184 mbpd and 183 mbpd of total fractionated products for the six months ended June 30, 2020 and 2019, respectively.

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(9) C2 + NGL pricing based on Mont Belvieu prices assuming an NGL barrel of approximately 35 percent ethane, 35 percent propane, six percent Iso-Butane, 12 percent normal butane and 12 percent natural gasoline.

LIQUIDITY AND CAPITAL RESOURCES

Cash Flows

Our cash and cash equivalents were $67 million at June 30, 2020 and $15 million at December 31, 2019. The change in cash, cash equivalents and restricted cash was due to the factors discussed below. Net cash provided by (used in) operating activities, investing activities and financing activities were as follows:

	Six Months Ended June 30,
(In millions)	2020			2019
Net cash provided by (used in):
Operating activities	$	2,114		$	1,954
Investing activities	(777		)	(1,439		)
Financing activities	(1,285		)	(568		)
Total	$	52		$	(53	)

Net cash provided by operating activities increased $160 million in the first six months of 2020 compared to the first six months of 2019, primarily due to increased net income of $22 million, excluding impairments, as well as other changes related to depreciation and amortization and changes in working capital items.

Net cash used in investing activities decreased $662 million in the first six months of 2020 compared to the first six months of 2019, primarily due to decreased spending related to the capital budget, a return of capital from our investments in Wink to Webster and Whistler and decreased contributions to equity method investments.

Financing activities were a $1,285 million use of cash in the first six months of 2020 compared to a $568 million use of cash in the first six months of 2019. The use of cash for the first six months of 2020 was primarily due to distributions of $1,445 million to common unitholders, distributions of $41 million to Series A preferred unitholders, distributions of $21 million to Series B preferred unitholders, distributions of $17 million to noncontrolling interests, repayment of $1,675 million on the MPLX Credit Agreement, payments of $7 million related to financing leases, and repayment of $3,302 million on the MPC Loan Agreement. These uses of cash were offset by borrowings of $2,500 million on the revolving credit facility, $2,708 million on the MPC Loan Agreement, and $20 million of contributions from MPC.

Debt and Liquidity Overview

Our outstanding borrowings at June 30, 2020 consist of the following:

(In millions)	June 30, 2020
MPLX LP:
Bank revolving credit facility	$	825
Term loan facility	1,000
Floating rate senior notes	2,000
Fixed rate senior notes	16,887
Consolidated subsidiaries:
MarkWest	23
ANDX	190
Financing lease obligations	13
Total	20,938
Unamortized debt issuance costs	(100		)
Unamortized discount/premium	(279		)
Amounts due within one year	(3		)
Total long-term debt due after one year	$	20,556

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Our intention is to maintain an investment grade credit profile. As of June 30, 2020, the credit ratings on our senior unsecured debt were at or above investment grade level as follows:

Rating Agency	Rating
Moody’s	Baa2 (negative outlook)
Standard & Poor’s	BBB (negative outlook)
Fitch	BBB (negative outlook)

The ratings reflect the respective views of the rating agencies. Although it is our intention to maintain a credit profile that supports an investment grade rating, there is no assurance that these ratings will continue for any given period of time. The ratings may be revised or withdrawn entirely by the rating agencies if, in their respective judgments, circumstances so warrant.

The MPLX Credit Agreement and Term Loan Agreement contain certain representations and warranties, affirmative and restrictive covenants and events of default that we consider to be usual and customary for an agreement of this type. The financial covenant requires MPLX to maintain a ratio of Consolidated Total Debt as of the end of each fiscal quarter to Consolidated EBITDA (both as defined in the MPLX Credit Agreement) for the prior four fiscal quarters of no greater than 5.0 to 1.0 (or 5.5 to 1.0 during the six-month period following certain acquisitions). Consolidated EBITDA is subject to adjustments for certain acquisitions completed and capital projects undertaken during the relevant period. Other covenants restrict us and/or certain of our subsidiaries from incurring debt, creating liens on assets and entering into transactions with affiliates. As of June 30, 2020, we were in compliance with the covenants, including the financial covenant with a ratio of Consolidated Total Debt to Consolidated EBITDA of 3.9 to 1.0.

The agreements governing our debt obligations do not contain credit rating triggers that would result in the acceleration of interest, principal or other payments solely in the event that our credit ratings are downgraded. However, any downgrades in the credit ratings of our senior unsecured debt ratings to below investment grade ratings could, among other things, increase the applicable interest rates and other fees payable under the MPLX Credit Agreement and the Term Loan Agreement and may limit our ability to obtain future financing, including refinancing existing indebtedness.

Our liquidity totaled $4.2 billion at June 30, 2020 consisting of:

	June 30, 2020
(In millions)	Total Capacity		Outstanding Borrowings			Available Capacity
Bank revolving credit facility due 2024(1)	$	3,500	$	(825	)	$	2,675
MPC Loan Agreement	1,500		—			1,500
Total liquidity	$	5,000	$	(825	)	4,175
Cash and cash equivalents						67
Total liquidity						$	4,242

(1) Outstanding borrowings include less than $1 million in letters of credit outstanding under this facility.

We expect our ongoing sources of liquidity to include cash generated from operations and borrowings under the MPC Loan Agreement, the MPLX Credit Agreement and access to capital markets. We believe that cash generated from these sources will be sufficient to meet our short-term and long-term funding requirements, including working capital requirements, capital expenditure requirements, contractual obligations, and quarterly cash distributions. MPC manages our cash and cash equivalents on our behalf directly with third-party institutions as part of the treasury services that it provides to us under our omnibus agreement. From time to time, we may also consider utilizing other sources of liquidity, including the formation of joint ventures or sales of non-strategic assets.

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Equity and Preferred Units Overview

Common units

The table below summarizes the changes in the number of units outstanding through June 30, 2020:

(In units)
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	253,291
Balance at June 30, 2020	1,058,608,762

ATM

MPLX expects the net proceeds, if any, from sales under our ATM Program will be used for general business purposes including repayment or refinancing of debt and funding for acquisitions, working capital requirements and capital expenditures. During the six months ended June 30, 2020, we issued no common units under our ATM program. As of June 30, 2020, $1.7 billion of common units remain available for issuance through the ATM Program.

Distributions

We intend to pay a minimum quarterly distribution to the holders of our common units of $0.2625 per unit, or $1.05 per unit on an annualized basis, to the extent we have sufficient cash from our operations after the establishment of cash reserves and the payment of costs and expenses, including reimbursements of expenses to our general partner. The amount of distributions paid under our policy and the decision to make any distributions is determined by our general partner, taking into consideration the terms of our partnership agreement. Such minimum distribution would equate to $278 million per quarter, or $1,112 million per year, based on the number of common units outstanding at June 30, 2020. On July 28, 2020, we announced the board of directors of our general partner had declared a distribution of $0.6875 per unit that will be paid on August 14, 2020 to unitholders of record on August 7, 2020. This is consistent with the first quarter 2020 distribution of $0.6875 per unit and an increase of 3.0 percent over the second quarter 2019 distribution. This rate will also be received by Series A preferred unitholders. Although our partnership agreement requires that we distribute all of our available cash each quarter, we do not otherwise have a legal obligation to distribute any particular amount per common unit.

Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the Board of Directors. Accordingly, a cash distribution payment totaling $21 million will be paid to Series B unitholders on August 17, 2020.

TexNew Mex units are entitled to receive quarterly distribution payments in an amount calculated using the distributable cash flow generated by a particular portion of the TexNew Mex pipeline system, in excess of a base amount and adjusted for previously agreed upon stipulations and contingencies. During the three months ended June 30, 2020 a distribution of $2 million was earned as a result of increased volumes on the TexNew Mex pipeline due to the idling of MPC’s Gallup, New Mexico refinery.

The allocation of total quarterly cash distributions is as follows for the three and six months ended June 30, 2020 and 2019. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

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	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per unit data)	2020		2019		2020		2019
Distribution declared:
Limited partner units - public	$	270	$	261	$	540	$	452
Limited partner units - MPC	445		431		903		763
Total LP distribution declared	715		692		1,443		1,215
Series A preferred units	21		21		41		41
Series B preferred units	10		21		21		21
Total distribution declared	746		734		1,505		1,277
Cash distributions declared per limited partner common unit	$	0.6875	$	0.6675	$	1.3750	$	1.3250

Capital Expenditures

Our operations are capital intensive, requiring investments to expand, upgrade, enhance or maintain existing operations and to meet environmental and operational regulations. Our capital requirements consist of maintenance capital expenditures and growth capital expenditures. Examples of maintenance capital expenditures are those made to replace partially or fully depreciated assets, to maintain the existing operating capacity of our assets and to extend their useful lives, or other capital expenditures that are incurred in maintaining existing system volumes and related cash flows. In contrast, growth capital expenditures are those incurred for capital improvements that we expect will increase our operating capacity to increase volumes gathered, processed, transported or fractionated, decrease operating expenses within our facilities or increase operating income over the long term. Examples of growth capital expenditures include the acquisition of equipment or the construction costs associated with new well connections, and the development of additional pipeline, processing or storage capacity. In general, growth capital includes costs that are expected to generate additional or new cash flow for MPLX.

Our capital expenditures are shown in the table below:

	Six Months Ended June 30,
(In millions)	2020			2019
Capital expenditures:
Maintenance	$	67		$	99
Maintenance reimbursements	(20		)	(16		)
Growth	469			961
Growth reimbursements	—			(12		)
Total capital expenditures	516			1,032
Less: (Decrease)/increase in capital accruals	(172		)	(77		)
Asset retirement expenditures	—			1
Additions to property, plant and equipment, net of reimbursements(1)	688			1,108
Investments in unconsolidated affiliates	222			323
Acquisitions	—			(6		)
Total capital expenditures and acquisitions	910			1,425
Less: Maintenance capital expenditures (including reimbursements)	47			83
Acquisitions	—			(6		)
Total growth capital expenditures(2)	$	863		$	1,348

(1) This amount is represented in the Consolidated Statements of Cash Flows as Additions to property, plant and equipment after excluding growth and maintenance reimbursements. Reimbursements are shown as Contributions from MPC within the Financing activities section of the Consolidated Statements of Cash Flows.

(2) Amount excludes contributions from noncontrolling interests of zero and $94 million for the six months ended June 30, 2020 and 2019, respectively, as reflected in the financing section of our statement of cash flows. Also excludes a $69 million return of capital from our Wink to Webster Pipeline joint venture in the first quarter of 2020 and a $41 million return of capital from our Whistler Pipeline joint venture in the second quarter of 2020. These are reflected in the investing section of our statement of cash flows for the six months ended June 30, 2020.

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Contractual Cash Obligations

As of June 30, 2020, our contractual cash obligations included long-term debt, finance and operating lease obligations, purchase obligations for services and to acquire property, plant and equipment, and other liabilities. During the six months ended June 30, 2020, our third-party, long-term debt obligations increased by $825 million and was primarily used to repay our MPC Loan Agreement. There were no other material changes to these obligations outside the ordinary course of business since December 31, 2019.

Off-Balance Sheet Arrangements

Off-balance sheet arrangements comprise those arrangements that may potentially impact our liquidity, capital resources and results of operations, even though such arrangements are not recorded as liabilities under U.S. GAAP. Our off-balance sheet arrangements are limited to indemnities and guarantees that are described in Note 21. Although these arrangements serve a variety of our business purposes, we are not dependent on them to maintain our liquidity and capital resources, and we are not aware of any circumstances that are reasonably likely to cause the off-balance sheet arrangements to have a material adverse effect on our liquidity and capital resources.

TRANSACTIONS WITH RELATED PARTIES

At June 30, 2020, MPC owned our non-economic general partnership interest and held approximately 63 percent of our outstanding common units.

Excluding revenues attributable to volumes shipped by MPC under joint tariffs with third parties that are treated as third-party revenues for accounting purposes, MPC accounted for 56 percent and 53 percent of our total revenues and other income for the second quarter of 2020 and 2019, respectively. We provide crude oil and product pipeline transportation services based on regulated tariff rates and storage services and inland marine transportation based on contracted rates.

Of our total costs and expenses, MPC accounted for 32 percent and 30 percent for the second quarter of 2020 and 2019, respectively. MPC performed certain services for us related to information technology, engineering, legal, accounting, treasury, human resources and other administrative services.

For further discussion of agreements and activity with MPC and related parties see Item 1. Business in our Annual Report on Form 10-K for the year ended December 31, 2019 and Note 5 of the Notes to Consolidated Financial Statements in this report.

ENVIRONMENTAL MATTERS AND COMPLIANCE COSTS

We have incurred and may continue to incur substantial capital, operating and maintenance, and remediation expenditures as a result of environmental laws and regulations. If these expenditures, as with all costs, are not ultimately reflected in the prices of our products and services, our operating results will be adversely affected. We believe that substantially all of our competitors must comply with similar environmental laws and regulations. However, the specific impact on each competitor may vary depending on a number of factors, including, but not limited to, the age and location of its operating facilities.

As of June 30, 2020, there have been no significant changes to our environmental matters and compliance costs since our Annual Report on Form 10-K for the year ended December 31, 2019.

CRITICAL ACCOUNTING ESTIMATES

As of June 30, 2020, there have been no significant changes to our critical accounting estimates since our Annual Report on Form 10-K for the year ended December 31, 2019, except as noted below.

Impairment Assessments of Long-Lived Assets, Intangible Assets, Goodwill and Equity Method Investments

Fair value calculated for the purpose of testing our long-lived assets, intangible assets, goodwill and equity method investments for impairment is estimated using the expected present value of future cash flows method and comparative market prices when appropriate. Significant judgment is involved in performing these fair value estimates since the results are based on forecasted assumptions. Significant assumptions include:

• Future Operating Performance. Our estimates of future operating performance are based on our analysis of various supply and demand factors, which include, among other things, industry-wide capacity, our planned utilization rate,

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end-user demand, capital expenditures and economic conditions as well as commodity prices. Such estimates are consistent with those used in our planning and capital investment reviews.

• Future volumes. Our estimates of future throughput of crude oil, natural gas, NGL and refined product volumes are based on internal forecasts and depend, in part, on assumptions about our customers’ drilling activity which is inherently subjective and contingent upon a number of variable factors (including future or expected pricing considerations), many of which are difficult to forecast. Management considers these volume forecasts and other factors when developing our forecasted cash flows.

• Discount rate commensurate with the risks involved. We apply a discount rate to our cash flows based on a variety of factors, including market and economic conditions, operational risk, regulatory risk and political risk. This discount rate is also compared to recent observable market transactions, if possible. A higher discount rate decreases the net present value of cash flows.

• Future capital requirements. These are based on authorized spending and internal forecasts.

Assumptions about the effects of COVID-19 and the macroeconomic environment are inherently subjective and contingent upon the duration of the pandemic and its impact on the macroeconomic environment, which is difficult to forecast. We base our fair value estimates on projected financial information which we believe to be reasonable. However, actual results may differ from these projections.

The need to test for impairment can be based on several indicators, including a significant reduction in prices of or demand for commodities, a poor outlook for profitability, a significant reduction in pipeline throughput volumes, a significant reduction in natural gas or NGL volumes processed, other changes to contracts or changes in the regulatory environment in which the asset or equity method investment is located.

Long-lived assets used in operations are assessed for impairment whenever changes in facts and circumstances indicate that the carrying value of the assets may not be recoverable based on the expected undiscounted future cash flow of an asset group. For purposes of impairment evaluation, long-lived assets must be grouped at the lowest level for which independent cash flows can be identified, which is at least at the segment level and in some cases for similar assets in the same geographic region where cash flows can be separately identified. If the sum of the undiscounted cash flows is less than the carrying value of an asset group, fair value is calculated, and the carrying value is written down if greater than the calculated fair value.

No impairment triggers were identified in the second quarter of 2020, however, during the first quarter of 2020, we identified an impairment trigger relating to asset groups within our Western G&P reporting unit as a result of significant impacts to forecasted cash flows for these asset groups resulting from the first quarter events and circumstances as discussed in Note 1 of the Notes to Consolidated Financial Statements. The cash flows associated with these assets were significantly impacted by volume declines reflecting decreased forecasted producer customer production as a result of lower commodity prices. After assessing each asset group within the Western G&P reporting unit for impairment, only the East Texas G&P asset group resulted in the fair value of the underlying assets being less than the carrying value. As a result, an impairment of $174 million of property, plant and equipment and $177 million of intangibles was recorded to “Impairment expense” on the Consolidated Statements of Income for the first quarter of 2020. Fair value of our PP&E was determined using a combination of an income and cost approach. The income approach utilized significant assumptions including management’s best estimates of the expected future cash flows and the estimated useful life of the asset group. The cost approach utilized assumptions for the current replacement costs of similar assets adjusted for estimated depreciation and deterioration of the existing equipment and economic obsolescence. The fair value of the intangibles was determined based on applying the multi-period excess earnings method, which is an income approach. Key assumptions included management’s best estimates of the expected future cash flows from existing customers, customer attrition rates and the discount rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of our impairment analysis will prove to be an accurate prediction of the future. The fair value measurements for the asset group fair values represent Level 3 measurements.

Unlike long-lived assets, goodwill must be tested for impairment at least annually, and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. Goodwill is tested for impairment at the reporting unit level. A goodwill impairment loss is measured as the amount by which a reporting unit’s carrying value exceeds its fair value, without exceeding the recorded amount of goodwill.

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The “Current Economic Environment” section describes the effects that the outbreak of COVID-19 and its development into a pandemic and the decline in commodity prices have had on our business. Due to these developments in the first quarter of 2020, we performed impairment assessments as discussed further below.

Prior to performing our goodwill impairment assessment as of March 31, 2020, MPLX had goodwill totaling approximately $9,536 million. As part of that assessment, MPLX recorded approximately $1,814 million of impairment expense in the first quarter of 2020 related to our Eastern G&P reporting unit within the G&P operating segment, which brought the amount of goodwill recorded within this reporting unit to zero. The impairment was primarily driven by updated guidance related to the slowing of drilling activity which has reduced production growth forecasts from our producer customers. For the remaining reporting units with goodwill, we determined that no significant adjustments to the carrying value of goodwill were necessary. The interim impairment assessment resulted in the fair value of the reporting units exceeding their carrying value by percentages ranging from approximately 8.5 percent to 270.0 percent. The reporting unit whose fair value exceeded its carrying amount by 8.5 percent, our Crude Gathering reporting unit, had goodwill totaling $1.1 billion at March 31, 2020. The operations which make up this reporting unit were acquired through the merger with ANDX. MPC accounted for its October 1, 2018 acquisition of Andeavor (including acquiring control of ANDX), using the acquisition method of accounting, which required Andeavor assets and liabilities to be recorded by MPC at the acquisition date fair value. The Merger was closed on July 30, 2019 and has been treated as a common control transaction, which required the recognition of assets acquired and liabilities assumed using MPC’s historical carrying value. As such, given the short amount of time from when fair value was established to the date of the impairment test, the amount by which the fair value exceeded the carrying value within this reporting unit is not unexpected. An increase of one percentage point to the discount rate used to estimate the fair value of this reporting unit would not have resulted in goodwill impairment as of March 31, 2020. No other reporting units had had fair values exceeding carrying values of less than 20 percent. There were no events or changes in circumstances noted in the second quarter of 2020 which would indicate it is more likely than not that the fair value of our reporting units with goodwill is less than their carrying amount.

Significant assumptions used to estimate the reporting units’ fair value included estimates of future cash flows and market information for comparable assets. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment tests will prove to be an accurate prediction of the future. See Note 12 of the Notes to Consolidated Financial Statements for additional information relating to goodwill.

Equity method investments are assessed for impairment whenever factors indicate an other than temporary loss in value. Factors providing evidence of such a loss include the fair value of an investment that is less than its carrying value, absence of an ability to recover the carrying value or the investee’s inability to generate income sufficient to justify our carrying value. During the first quarter of 2020, we assessed certain of our equity method investments for impairment as a result of a number of first quarter events and circumstances as discussed in Note 1 of the Notes to Consolidated Financial Statements. As a result, we recorded an other than temporary impairment for three joint ventures in which we have an interest. Impairment of these investments was $1,264 million, of which $1,251 million was related to MarkWest Utica EMG, L.L.C. and its investment in Ohio Gathering Company, L.L.C. The fair value of the investments was determined based upon applying the discounted cash flow method, which is an income approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future cash flows, including prices and volumes, the weighted average cost of capital and the long-term growth rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As such, the fair value of these equity method investments represents a Level 3 measurement. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment test will prove to be an accurate prediction of the future. The impairment was recorded through “Income from equity method investments.” The impairments were largely due to a reduction in forecasted volumes gathered and processed by the systems operated by the joint ventures. At June 30, 2020 we had $4,065 million of equity method investments recorded on the Consolidated Balance Sheets.

An estimate of the sensitivity to net income resulting from impairment calculations is not practicable, given the numerous assumptions (e.g., pricing, volumes and discount rates) that can materially affect our estimates. That is, unfavorable adjustments to some of the above listed assumptions may be offset by favorable adjustments in other assumptions. See Note 4 of the Notes to Consolidated Financial Statements for additional information relating to equity method investments.

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ACCOUNTING STANDARDS NOT YET ADOPTED

While new financial accounting pronouncements will be effective for our financial statements in the future, there are no standards that have not yet been adopted that are expected to have a material impact on our financial statements. Accounting standards are discussed in Note 2 of the Notes to Consolidated Financial Statements.

Item 3. Quantitative and Qualitative Disclosures about Market Risk

We are exposed to market risks related to the volatility of commodity prices. We employ various strategies, including the potential use of commodity derivative instruments, to economically hedge the risks related to these price fluctuations. We are also exposed to market risks related to changes in interest rates. As of June 30, 2020, we did not have any open financial derivative instruments to economically hedge the risks related to interest rate fluctuations or commodity derivative instruments to economically hedge the risks related to the volatility of commodity prices; however, we continually monitor the market and our exposure and may enter into these arrangements in the future. While there is a risk related to changes in fair value of derivative instruments we may enter into; such risk is mitigated by price or rate changes related to the underlying commodity or financial transaction.

Commodity Price Risk

The information about commodity price risk for the three and six months ended June 30, 2020 does not differ materially from that discussed in Item 7A. Quantitative and Qualitative Disclosures about Market Risk of our Annual Report on Form 10-K for the year ended December 31, 2019.

Outstanding Derivative Contracts

We have a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2022. The customer has the unilateral option to extend the agreement for two consecutive five-year terms through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending options have been aggregated into a single compound embedded derivative. The probability of the customer exercising its options is determined based on assumptions about the customer’s potential business strategy decision points that may exist at the time they would elect whether to renew the contract. The changes in fair value of this compound embedded derivative are based on the difference between the contractual and index pricing and the probability of the producer customer exercising its option to extend. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. As of June 30, 2020 and December 31, 2019, the estimated fair value of this contract was a liability of $51 million and $60 million, respectively.

Open Derivative Positions and Sensitivity Analysis

As of June 30, 2020, we have no open commodity derivative contracts. We evaluate our portfolio of commodity derivative instruments on an ongoing basis and add or revise strategies in anticipation of changes in market conditions and in risk profiles.

Interest Rate Risk

Sensitivity analysis of the effect of a hypothetical 100-basis-point change in interest rates on long-term debt, excluding finance leases, is provided in the following table. Fair value of cash and cash equivalents, receivables, accounts payable and accrued interest approximate carrying value and are relatively insensitive to changes in interest rates due to the short-term maturity of the instruments. Accordingly, these instruments are excluded from the table.

(In millions)	Fair value as of June 30, 2020(1)		Change in Fair Value(2)		Change in Income Before Income Taxes for the Six Months Ended June 30, 2020(3)
Long-term debt
Fixed-rate	$	18,121	$	1,683	N/A
Variable-rate	$	3,798	$	33	$	17

(1) Fair value was based on market prices, where available, or current borrowing rates for financings with similar terms and maturities.

(2) Assumes a 100-basis-point decrease in the weighted average yield-to-maturity at June 30, 2020.

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(3) Assumes a 100-basis-point change in interest rates. The change to net income was based on the weighted average balance of all outstanding variable-rate debt for the six months ended June 30, 2020.

At June 30, 2020, our portfolio of long-term debt consisted of fixed-rate instruments and variable-rate instruments including our term loan, floating rate senior notes and our revolving credit facility. The fair value of our fixed-rate debt is relatively sensitive to interest rate fluctuations. Our sensitivity to interest rate declines and corresponding increases in the fair value of our debt portfolio unfavorably affects our results of operations and cash flows only when we elect to repurchase or otherwise retire fixed-rate debt at prices above carrying value. Interest rate fluctuations generally do not impact the fair value of borrowings under our bank revolving credit or term loan facilities, but may affect our results of operations and cash flows. As of June 30, 2020, we did not have any financial derivative instruments to hedge the risks related to interest rate fluctuations; however, we continually monitor the market and our exposure and may enter into these agreements in the future.

Item 4. Controls and Procedures

Disclosure Controls and Procedures

An evaluation of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended) was carried out under the supervision and with the participation of management, including the chief executive officer and chief financial officer of our general partner. Based upon that evaluation, the chief executive officer and chief financial officer of our general partner concluded that the design and operation of these disclosure controls and procedures were effective as of June 30, 2020, the end of the period covered by this report.

Changes in Internal Control Over Financial Reporting

During the quarter ended June 30, 2020, there were no changes in our internal control over financial reporting that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Part II – Other Information

Item 1. Legal Proceedings

We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Except as described below, there have been no material changes to the legal proceedings previously disclosed in our Annual Report on Form 10-K, as updated in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020.

Litigation

Dakota Access Pipeline

In connection with our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL, we have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, have agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system.

As previously disclosed in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, in March 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits for the Bakken Pipeline system, to conduct a full environmental impact statement (“EIS”), and further requested briefing on whether an easement permit necessary for the operation of the Bakken Pipeline system should be vacated while the EIS is being prepared.

On July 6, 2020, the D.D.C. ordered vacatur of the easement permit during the pendency of an EIS and further ordered shut down of the pipeline by August 5, 2020. The D.D.C. denied a motion to stay that order. Dakota Access and the Army Corps are appealing the D.D.C.’s order to the U.S. Court of Appeals for the District of Columbia Circuit. On July 14, 2020, the Circuit

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Court issued an administrative stay while the court considers Dakota Access and the Army Corps’ emergency motion for stay pending appeal.

If the pipeline is temporarily shutdown pending completion of the EIS, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the 1% redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest.

Tesoro High Plains Pipeline

In early July, MPLX received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification covers the rights of way for 23 tracts of land and demands the immediate cessation of pipeline operations. The notification also assesses trespass damages of approximately $187 million. MPLX expects to receive a notification for an additional 11 tracts in the near future. We appealed this determination, which triggered an automatic stay of the requested pipeline shutdown and payment. We believe the trespass damage calculation is dependent on a novel interpretation of the applicable law, and we continue to actively negotiate settlement of this matter with holders of the property rights at issue. Management does not believe the ultimate resolution of this matter will have a material adverse effect on our consolidated financial position, results of operations, or cash flows.

Environmental Proceedings

Gathering and Processing

On May 7, 2020, we received a show cause letter from the U.S. EPA relating to alleged violations relating to MPLX’s compliance under its Sarsen facility LDAR consent decree. We have reached a settlement in principle to resolve this matter with a cash penalty of $150,000. We expect the settlement will be finalized and the penalty will be paid in the third quarter of 2020.

On May 13, 2020, we received an offer from the Texas Commission on Environmental Quality to settle alleged violations relating to the installation of high bleed pneumatic controllers at its Hancock Compressor Station and Carthage East Gas Plant. We have reached an agreement to settle this matter for a cash penalty of $165,600.

Item 1A. Risk Factors

There have been no material changes from the risk factors previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2019, as updated in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020.

Item 5. Other Information

On July 31, 2020, MPLX entered into a Redemption Agreement (the “Redemption Agreement”) with Western Refining Southwest, Inc., an Arizona corporation (“WRSW”) and wholly owned subsidiary of MPC, pursuant to which MPLX agreed to transfer, following a series of intercompany transactions, all of the outstanding membership interests in Western Refining Wholesale, LLC, a Delaware limited liability company (“WRW”) to WRSW in exchange for the redemption of MPLX common units held by WRSW.  The transaction effects the transfer to MPC of the Western wholesale distribution business that MPLX acquired as a result of its acquisition of ANDX. The Redemption Agreement was approved by the conflicts committee and the board of directors of MPLX’s general partner. The conflicts committee, which is composed of independent members of the board of directors of MPLX’s general partner, retained independent legal and financial advisors to assist it in evaluating and negotiating the transaction.

Consistent with the terms of the Redemption Agreement, effective as of 11:59 p.m. on July 31, 2020 (the “Closing”), all of the outstanding membership interests in WRW were transferred to WRSW, and WRW became an indirect, wholly owned subsidiary of MPC. At the Closing, per the terms of Redemption Agreement, MPLX redeemed 18,582,088 Common Units (the “Redeemed Units”) held by WRSW. The number of Redeemed Units was calculated by dividing WRW’s aggregate valuation of $340 million by the simple average of the volume weighted average New York Stock Exchange prices of an MPLX Common

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Unit for the ten trading days ending at market close on July 27, 2020. Following the redemption of the Redeemed Units, and consistent with the terms of the Redemption Agreement, MPLX cancelled the Redeemed Units.

After giving effect to transactions contemplated under the Redemption Agreement (including the cancellation of the Redeemed Units as described above), MPC holds, indirectly through its subsidiaries, 647,415,452 common units constituting approximately 62% of the MPLX common units issued and outstanding as of August 3, 2020.

Each of MPLX and WRSW has agreed to customary representations, warranties and covenants, as well as customary indemnification obligations between the parties, in the Redemption Agreement.

The foregoing description of the Redemption Agreement is not complete and is qualified in its entirety by reference to the full text of the Redemption Agreement, which is filed as Exhibit 10.1 to this Quarterly Report on Form 10-Q and incorporated by reference herein.

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Item 6. Exhibits

		Incorporated by Reference From
Exhibit Number	Exhibit Description	Form	Exhibit	Filing Date	SEC File No.	Filed Herewith	Furnished Herewith
1.1	Underwriting Agreement, dated as of September 4, 2019, among the Issuer, MPLX GP LLC, the general partner of the Issuer, and each of Citigroup Global Markets Inc., Barclays Capital Inc. and RBC Capital Markets, LLC, acting as representatives of the several underwriters named therein	8-K	1.1	9/9/2019	001-35714
2.1*	Agreement and Plan of Merger, dated as of May 7, 2019, by and among Andeavor Logistics LP, Tesoro Logistics GP, LLC, MPLX LP, MPLX GP LLC and MPLX MAX LLC.	8-K	2.1	5/8/2019	001-35714
3.1	Certificate of Limited Partnership of MPLX LP	S-1	3.1	7/2/2012	333-182500
3.2	Amendment to the Certificate of Limited Partnership of MPLX LP	S-1/A	3.2	10/9/2012	333-182500
3.3	Fifth Amended and Restated Agreement of Limited Partnership of MPLX LP, dated as of July 30, 2019	8-K/A	3.1	8/14/2019	001-35714
10.1	Redemption Agreement, dated July 31, 2020, between MPLX LP and Western Refining Southwest, Inc.					X
31.10	Certification of Chief Executive Officer pursuant to Rule 13a-14 and 15d-14 under the Securities Exchange Act of 1934					X
31.20	Certification of Chief Financial Officer pursuant to Rule 13a-14 and 15d-14 under the Securities Exchange Act of 1934					X
32.10	Certification of Chief Executive Officer pursuant to 18 U.S.C. Section 1350						X
32.20	Certification of Chief Financial Officer pursuant to 18 U.S.C. Section 1350						X
101.INS	XBRL Instance Document: The instance document does not appear in the interactive data file because its XBRL tags are embedded within the Inline XBRL document.
101.SCH	Inline XBRL Taxonomy Extension Schema Document.					X
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document.					X
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document.					X
101.LAB	Inline XBRL Taxonomy Extension Label Linkbase Document.					X
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document.					X

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		Incorporated by Reference From
Exhibit Number	Exhibit Description	Form	Exhibit	Filing Date	SEC File No.	Filed Herewith	Furnished Herewith
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101).

* Schedules have been omitted pursuant to Item 601(b)(2) of Regulation S-K. MPLX LP hereby undertakes to furnish supplementally a copy of any omitted schedule upon request by the SEC.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	MPLX LP
	By:	MPLX GP LLC
		Its general partner
Date: August 3, 2020	By:	/s/ C. Kristopher Hagedorn
		C. Kristopher Hagedorn
		Vice President and Controller of MPLX GP LLC (the general partner of MPLX LP)

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EX-10.1

Exhibit 10.1

REDEMPTION AGREEMENT

between

MPLX LP

and

Western Refining Southwest, Inc.

Dated July 31, 2020

REDEMPTION AGREEMENT

THIS REDEMPTION AGREEMENT (this “Agreement”) is entered into on July 31, 2020 (the “Execution Date”), by and between MPLX LP, a Delaware limited partnership (“MPLX”), and Western Refining Southwest Inc., an Arizona corporation (“WRS” and, together with MPLX, the “Parties” and each individually a “Party”).

WITNESS:

WHEREAS, WNRL Energy, LLC (“Energy”) is the owner and holder of record of 100% of the outstanding limited liability company membership interests in Western Refining Wholesale, LLC (“Wholesale”) (the “Wholesale Membership Interests”);

WHEREAS, Wholesale is the owner and holder of record of 100% of the outstanding limited liability company membership interests in Western Refining Product Transport, LLC (“Transport”) (the “Transport Membership Interests” and together with the Wholesale Membership Interests, the “Membership Interests”);

WHEREAS, MPLX is the owner, directly or indirectly, of 100% of the outstanding partnership interests in Andeavor Logistics LP (“ANDX”), which in turn is the owner and holder of record of 100% of the outstanding limited liability company membership interests of Western Refining Logistics LP (“Logistics”), which in turn is the owner and holder of record of 100% of the outstanding limited liability company membership interests in WNRL Energy GP, LLC (“Energy GP”);

WHEREAS, Logistics is the owner and holder of record of 99.9% of the outstanding limited liability company membership interests in Energy, and Energy GP is the owner and holder of record of 0.1% of the outstanding limited liability company membership interests in Energy;

WHEREAS, Energy is willing and desires to distribute the Wholesale Membership Interests to Energy GP and Logistics, and Energy GP is willing and desires to distribute the Wholesale Membership Interests it receives from Energy to Logistics;

WHEREAS, Logistics is willing and desires to distribute the Wholesale Membership Interests it receives from Energy and Energy GP to ANDX;

WHEREAS, ANDX is willing and desires to distribute the Wholesale Membership Interests it receives from Logistics to MPLX;

WHEREAS, WRS is willing and desires to acquire from MPLX, and MPLX is willing to distribute to WRS, in exchange for and in redemption of Common Units of MPLX owned by WRS, the Wholesale Membership Interests on the terms and conditions set out below; and

WHEREAS, the Parties are willing to make the representations, warranties and covenants and to provide the consideration described in this Agreement.

NOW, THEREFORE, in consideration of the promises and mutual representations, warranties and covenants in this Agreement, the Parties agree as follows:

1

ARTICLE I

DEFINITIONS

Section 1.1Capitalized terms used in this Agreement have the meanings and are subject to the rules of construction set forth in Appendix A.

ARTICLE II

TRANSFER OF WHOLESALE MEMBERSHIP INTERESTS

Section 2.1Transfer of the Wholesale Membership Interests. Notwithstanding anything in Wholesale’s Organizational Documents to the contrary, subject to the terms and conditions provided for in this Agreement, the following transactions shall each be deemed to have occurred for all purposes in the order in which they are set forth in this Section 2.1 on the Closing Date or upon such date as otherwise stated below:

(a)Energy shall distribute, grant, convey, assign, transfer, set over and deliver (i) to Energy GP, 0.1% of Energy’s right, title and interest in and to the Wholesale Membership Interests, and (ii) to Logistics, 99.9% of Energy’s right, title and interest in and to the Wholesale Membership Interests (clauses (i) and (ii), collectively, the “Energy Distributions”);

(b)Energy GP shall distribute, grant, convey, assign, transfer, set over and deliver to Logistics all of Energy GP’s right, title and interest in and to its share of the Wholesale Membership Interests (the “Energy GP Distribution”);

(c)Logistics shall distribute, grant, convey, assign, transfer, set over and deliver to ANDX, all of Logistics’ right, title and interest in and to the Wholesale Membership Interests (the “Logistics Distribution”);

(d)ANDX shall distribute, grant, convey, assign, transfer, set over and deliver to MPLX all of ANDX’s right, title and interest in and to the Wholesale Membership Interests (the “ANDX Distribution” and, collectively with the Energy Distributions, the Energy GP Distribution and the Logistics Distribution, the “Wholesale Distributions”); and

(e)Within five (5) days of the Closing Date MPLX shall distribute, grant, convey, assign, transfer, set over and deliver to WRS, in exchange for the consideration set forth in Section 3.1, all of MPLX’s right, title and interest in and to the Wholesale Membership Interests (the “Transfer”).

Notwithstanding the foregoing, in lieu of one or more conveyance documents regarding the Wholesale Membership Interests and for administrative convenience only (and without limiting any of the representations, warranties, covenants or other provisions of this Agreement), MPLX agrees to deliver or cause to be delivered all of MPLX’s right, title and interest in and to the Wholesale Membership Interests to WRS.

2

ARTICLE III

CONSIDERATION

Section 3.1Redemption of MPLX Common Units. In consideration of the Transfer and subject to the terms and conditions provided for in this Agreement, MPLX shall redeem [Ÿ] Common Units, valued at $340,000,000 (the “Total Value”), from WRS (the “MPLX Common Units”). For the avoidance of doubt, the foregoing number of Common Units was determined by dividing the Total Value by the simple average of the volume weighted average price of a Common Unit on the NYSE for the ten trading days ending at market close on July [27], 2020. Thereafter, MPLX shall cancel the MPLX Common Units.

ARTICLE IV

INDEMNIFICATION

Section 4.1Indemnification by MPLX.

(a)Subject to Section 4.3, from and after the Closing Date, MPLX shall indemnify, defend and hold harmless WRS, and any other of WRS’s Affiliates and its and their respective directors, members, officers, employees, and representatives (the “WRS Indemnitees”), from and against any losses, liabilities, liens, encumbrances, costs, damages, deficiencies, diminution in value, judgments, demands, suits, assessments, charges, fines, penalties, or expenses (including reasonable attorneys’ fees and other costs of litigation) (“Losses”) actually suffered or incurred by any of them resulting from, related to, or arising out of (i) the breach of any representation or warranty of MPLX contained in this Agreement, in any Exhibit or Appendix to this Agreement or in any document, instrument, agreement or certificate delivered under this Agreement or (ii) any Energy Taxes.

(b)Solely for the purpose of indemnification pursuant to Section 4.1(a)(i), the representations and warranties of MPLX in this Agreement shall be deemed to have been made without regard to any materiality or Material Adverse Effect qualifiers.

Section 4.2Indemnification by WRS.

(a)Subject to Section 4.3, from and after the Closing Date, WRS shall indemnify, defend and hold harmless MPLX, and any other of MPLX’s Affiliates and its and their respective directors, members, officers, employees, and representatives (the “MPLX Indemnitees”), from and against any Losses actually suffered or incurred by any of them resulting from, related to, or arising out of the breach of any representation, warranty or covenant of WRS contained in this Agreement, in any Exhibit or Appendix to this Agreement or in any document, instrument, agreement or certificate delivered under this Agreement.

(b)Solely for the purpose of indemnification pursuant to Section 4.2(a)(i), the representations and warranties of WRS in this Agreement shall be deemed to have been made without regard to any materiality or Material Adverse Effect qualifiers.

Section 4.3Limitations on Indemnities.

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(a)Subject to the limitations and other provisions of this Agreement, the representations and warranties of the Parties hereto contained in this Agreement and the covenants and agreements of the Parties hereto contained herein required to be fully performed on or before the Closing shall survive for a period of one (1) year from the Closing Date, except for (i) the representations and warranties contained in Sections5.1, 5.2, 5.3, 5.7, 6.1, 6.2, 6.3, and 6.5 (collectively, the “Fundamental Representations”), which shall survive for a period of three (3) years from the Closing Date, and (ii) the representations and warranties contained in Section 5.10 (Taxes), which shall survive until the date that is sixty (60) days after the expiration of the applicable statutes of limitations (including all periods of extension and tolling). Each covenant and agreement of the Parties in this Agreement which by its terms requires performance after the Closing Date shall survive the Closing and shall remain in full force and effect until such covenant or agreement is fully performed. If a notice of a claim for indemnification under this Article IV has been timely given in accordance with this Agreement prior to the expiration of the applicable survival period for the applicable representation, warranty or covenant, then the applicable representation, warranty or covenant shall survive as to such claim, until such claim has been finally resolved.

(b)To the extent the WRS Indemnitees are entitled to indemnification for Losses pursuant to Section 4.1(a)(i) (but not including Losses with respect to breaches of Fundamental Representations, the representations and warranties contained in Section 5.10 (Taxes), or Energy Taxes), MPLX shall not be liable for those Losses unless the aggregate amount of such Losses exceeds the Deductible, and then only to the extent of any such excess; provided, however, that the aggregate liability to the WRS Indemnitees pursuant to such Sections (but not including Losses with respect to breaches of Fundamental Representations, the representations and warranties contained in Section 5.10 (Taxes), or Energy Taxes) shall not exceed the Cap. The maximum aggregate liability of MPLX for Losses under Section 4.1(a) shall not exceed the Total Value.

(c)NOTWITHSTANDING ANYTHING TO THE CONTRARY CONTAINED IN THIS AGREEMENT, NO PARTY HERETO SHALL BE ENTITLED TO RECOVER FROM ANY OTHER PARTY HERETO ANY AMOUNT IN RESPECT OF EXEMPLARY, PUNITIVE, REMOTE OR SPECULATIVE DAMAGES, EXCEPT, IN EACH CASE, TO THE EXTENT SUCH DAMAGES ARE FINALLY AND JUDICIALLY DETERMINED AND PAID TO AN UNAFFILIATED THIRD PARTY. ALL RELEASES, DISCLAIMERS, LIMITATIONS ON LIABILITY AND INDEMNITIES IN THIS AGREEMENT, INCLUDING THOSE IN THIS Article IV, SHALL APPLY EVEN IN THE EVENT OF THE SOLE, JOINT, AND/OR CONCURRENT, ACTIVE OR PASSIVE NEGLIGENCE, STRICT LIABILITY OR FAULT OF THE PARTY WHOSE LIABILITY IS RELEASED, DISCLAIMED, LIMITED OR INDEMNIFIED (EXCLUDING GROSS NEGLIGENCE, FRAUD OR WILLFUL MISCONDUCT).

Section 4.4Indemnification Procedures. A WRS Indemnitee or MPLX Indemnitee, as the case may be (an “Indemnified Party”), shall give the indemnifying party under Section 4.1 or Section 4.2, as applicable (an “Indemnifying Party”), prompt written notice of any matter which it has determined has given or could give rise to a right of indemnification under this Agreement that does not involve a third party, stating the amount of the Loss, if known, and method of

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computation thereof, containing a reference to the provisions of this Agreement in respect of which such right of indemnification is claimed or arises; provided, however, that the failure to provide such notice shall not release the Indemnifying Party from its obligations under this Article IV except to the extent the Indemnifying Party is prejudiced by such failure. With respect to a claim for indemnification involving a claim by a third party, the procedures with respect to indemnification shall be governed by the terms of Exhibit 1.

Section 4.5Additional Matters. The representations, warranties and covenants of an Indemnifying Party, and an Indemnified Party’s right to indemnification with respect thereto, shall not be affected or deemed waived by reason of any investigation made by or on behalf of such Indemnified Party or by reason of the fact that such Indemnified Party or any of its Affiliates, advisors or representatives knew or should have known that any such representation or warranty is, was or might be inaccurate.

Section 4.6Exclusive Remedy. From and after Closing, no Party shall have liability under this Agreement or the transactions contemplated hereby except as is provided in this Article IV other than claims or causes of action arising from fraud or willful misconduct.

ARTICLE V

REPRESENTATIONS AND WARRANTIES OF MPLX

MPLX represents and warrants as of the date hereof as follows:

Section 5.1Ownership Interests.

(a)To MPLX’s Knowledge, the Wholesale Membership Interests were duly authorized, validly issued, fully paid (to the extent required by the Organizational Documents of Wholesale) and nonassessable (except, to the extent applicable, as such nonassessability may be affected by Sections 18-303, 18-607 and 18-804 of the DLLCA). Immediately following the consummation of the Wholesale Distributions, MPLX will have good and valid record and beneficial title to the Wholesale Membership Interests, free and clear of any and all Liens, and, except as provided or created by the limited liability company agreement or other Organizational Documents of Wholesale, the 1933 Act or applicable state securities laws, the Wholesale Membership Interests will be free and clear of any restrictions on transfer or, to MPLX’s Knowledge, claims. To MPLX’s Knowledge, except as set forth in the Organizational Documents of MPLX, Wholesale or Transport there are no options, warrants, purchase rights, contracts, commitments or other securities exercisable or exchangeable for the Wholesale Membership Interests, or any other commitments or agreements of MPLX, Wholesale or Transport or any of their respective controlled Affiliates providing for the issuance of additional Equity Interests in Wholesale or Transport, or for the repurchase or redemption of any of the Wholesale Membership Interests, or any agreements of any kind which may obligate Wholesale or Transport to issue, purchase, register for sale, redeem or otherwise acquire any of its Equity Interests. Immediately following the Transfer, WRS will have good and valid record and beneficial title to the Wholesale Membership Interests, free and clear of any Liens and, except as provided or created by the limited liability company agreement or other

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Organizational Documents of Wholesale, the 1933 Act or applicable state securities laws, free and clear of any restrictions on transfer or, to MPLX’s Knowledge, claims.

(b)To MPLX’s Knowledge, the Transport Membership Interests were duly authorized, validly issued, fully paid (to the extent required by the Organizational Documents of Transport) and nonassessable (except, to the extent applicable, as such nonassessability may be affected by Sections 18-303, 18-607 and 18-804 of the DLLCA). Wholesale owns all of the Transport Membership Interests. To MPLX’s Knowledge, none of the Transport Membership Interests (i) are, except as set forth in the Organizational Documents of Transport, subject to or (ii) were issued in violation of any purchase option, call option, right of first refusal, preemptive right, subscription right or any similar right under any provision of local or state law applicable to the Transport Membership Interests, the Organizational Documents of Transport, or any contract, arrangement or agreement to which MPLX, Wholesale, Transport, or any of their respective controlled Affiliates is a party or to which it or any of their respective properties or assets is otherwise bound. Wholesale has good and valid and beneficial title to the Transport Membership Interests free and clear of all Liens.

Section 5.2Organization and Existence.

(a)MPLX is a limited partnership duly organized, validly existing and in good standing under the laws of the State of Delaware and is qualified to conduct business in each jurisdiction where the nature of its business or the ownership of its properties require it to be qualified, except where the failure to be so qualified would not constitute a Material Adverse Effect.

(b)To MPLX’s Knowledge, Wholesale has been duly organized and is validly existing and in good standing under the laws of the State of Delaware, with full limited liability company power and authority to operate and to carry on its business as it is currently conducted as of the date hereof. Wholesale is duly qualified to transact business and is in good standing as a foreign entity in each other jurisdiction in which such qualification is required for the conduct of its business, except where the failure to so qualify or to be in good standing does not or if continued would not have a Material Adverse Effect. MPLX has delivered to WRS correct and complete copies of Wholesale’s respective Organizational Documents. Wholesale is not in breach or default under the terms of any Organizational Document to which it is a party.

(c)To MPLX’s Knowledge, Transport has been duly organized and is validly existing and in good standing under the laws of the State of Delaware, with full limited liability company power and authority to operate and to carry on its business as it is currently conducted as of the date hereof. Transport is duly qualified to transact business and is in good standing as a foreign entity in each other jurisdiction in which such qualification is required for the conduct of its business, except where the failure to so qualify or to be in good standing does not or if continued would not have a Material Adverse Effect. MPLX has delivered to WRS correct and complete copies of Transport’s Organizational Documents. Transport is not in breach or default under the terms of any of Organizational Document to which it is a party.

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Section 5.3Authority and Action. MPLX has the limited partnership power and authority to enter into this Agreement and each agreement and instrument to be executed and delivered by MPLX pursuant hereto and to perform all of its obligations and consummate the transactions contemplated hereby and thereby. MPLX has taken all necessary and appropriate action to authorize, execute and deliver this Agreement and each agreement and instrument to be executed and delivered by MPLX pursuant hereto and to consummate the transactions contemplated hereby and thereby. This Agreement has been, and each agreement and instrument to be executed and delivered by MPLX pursuant hereto will be when so executed and delivered, duly and validly executed and delivered by MPLX and this Agreement is, and each agreement and instrument to be executed and delivered by MPLX pursuant hereto will be when so executed and delivered, a valid and binding obligation of MPLX, enforceable in accordance with its terms, except as such enforcement may be limited by applicable bankruptcy, insolvency, moratorium or similar laws affecting the rights of creditors generally and by general principles of equity.

Section 5.4Consents. No consent, approval, license, permit, order, waiver, or authorization of, or registration, declaration, or filing with, any Governmental Authority or other Person is required to be obtained or made by or with respect to MPLX, Wholesale, Transport, or the Wholesale Membership Interests in connection with:

(a)the execution, delivery, and performance of this Agreement (or any related instrument or agreement), or the consummation of the transactions contemplated hereby and thereby;

(b)the enforcement against MPLX of its obligations hereunder and thereunder; or

(c)following the Closing, the ownership by WRS of the Wholesale Membership Interests;

except, in each case, as would not have, individually or in the aggregate, a Material Adverse Effect or result in any material loss, cost or liability of WRS or its Subsidiaries (including, from and after the Closing, Wholesale or Transport).

Section 5.5No Violation. The execution and delivery of this Agreement (or any related instrument or agreement to be executed and delivered) by MPLX does not, or when executed will not, and the consummation of the transactions contemplated hereby or thereby and the performance by MPLX of the obligations that it is obligated to perform hereunder or thereunder do not:

(a)conflict with or result in a breach of any of the provisions of any Organizational Documents of MPLX, Wholesale or Transport;

(b)result in the creation, violation or acceleration of, or afford any Person the right to obtain, or accelerate any obligation or indebtedness under, any Lien on the Membership Interests, or on property or assets of MPLX, Wholesale, or Transport under any indenture, mortgage, lien, agreement, contract, commitment or instrument;

(c)conflict with any municipal, state or federal ordinance, law (including common law), rule, regulation, judgment, order, writ, injunction, or decree applicable to MPLX, Wholesale or Transport; or

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(d)conflict with, result in a breach of, constitute a default under (whether with notice or the lapse of time or both) or accelerate or permit the acceleration of the performance required by, or require consent, authorization or approval under any Wholesale Material Contract or any Transport Material Contract, any indenture, mortgage, lien or agreement, contract, commitment or instrument to which MPLX, Wholesale or Transport is a party or by which any of them is bound or to which any of the Wholesale Membership Interests are subject; except, in the case of clauses (b), (c) and (d), as would not have, individually or in the aggregate, a Material Adverse Effect or result in any material loss, cost or liability of WRS or its Subsidiaries (including, from and after the Closing, Wholesale or Transport).

Section 5.6Information.

(a)To MPLX’s Knowledge, this Agreement (and all related documents) does not contain any untrue statement of a material fact or omit to state any material fact necessary to make the statements herein not misleading and MPLX has not intentionally withheld disclosure from the Conflicts Committee of any fact that would constitute a Material Adverse Effect.

(b)The historical and pro forma operations, income and EBITDA information provided to the Conflicts Committee and its financial advisor as part of the Conflicts Committee’s review in connection with this Agreement have a reasonable basis, were prepared in good faith and are consistent with MPLX’s (and its applicable Affiliates’) management’s current expectations, which MPLX (and its applicable Affiliate) believes are reasonable, and are derived from, and consistent in all material respects with, MPLX’s (and its applicable Affiliates’) books and records.

Section 5.7Brokers. Neither MPLX nor any of its Affiliates has incurred any liability, contingent or otherwise, for any brokerage fee, commission or financial advisory fee in connection with the transactions contemplated by this Agreement.

Section 5.8Laws and Regulations; Litigation. There are no pending or, to MPLX’s Knowledge, threatened claims, fines, actions, suits, demands, investigations or proceedings or any arbitration or binding dispute resolution proceeding (collectively, “Litigation”) against any of MPLX, Wholesale or Transport or against or affecting the Wholesale Membership Interests, or the ownership of the Wholesale Membership Interests that (a) have, or would be likely to have, a Material Adverse Effect or (b) seek any material injunctive relief with respect to the Wholesale Membership Interests. Except as would not, individually or in the aggregate, have a Material Adverse Effect, none of Wholesale or Transport is in violation of or in default under any municipal, state or federal ordinance, law (including common law), rule or regulation or under any order of any Governmental Authority.

Section 5.9Title to Assets. Disclosure Schedule 5.9 sets forth a true and complete list of the material assets held by each of Wholesale (the “Wholesale Assets”) and Transport (the “TransportAssets”). To MPLX’s Knowledge, each of Wholesale and Transport has good and marketable title to all respective tangible personal property included in the Wholesale Assets and Transport Assets respectively, free and clear of all Liens, except Permitted Liens. To MPLX’s Knowledge, all tangible personal property included in the Wholesale Assets and Transport Assets

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is (a) in the aggregate, in good operating condition and repair (normal wear and tear excepted); (b) has been maintained in all material respects in accordance with applicable laws and regulations, as well as generally accepted industry practice; and (c) is sufficient for the purposes for which it is currently being used or held for use. The Wholesale Assets and Transport Assets constitute all of the material assets related to the ownership, use and operation of the Wholesale Business and Transport Business, as applicable, and are sufficient to own and operate the Wholesale Business and Transport Business, respectively, as of the date hereof.

Section 5.10Taxes.

(a)To MPLX’s Knowledge and with respect to all Tax periods in which MPLX has directly or indirectly owned Wholesale and Transport:

(i)All material Tax Returns that are required to be filed by or with respect to Wholesale and Transport on or prior to the Closing Date (taking into account any valid extension of time within which to file) have been or will be timely filed on or prior to the Closing Date and all such Tax Returns are true, correct and complete in all material respects.

(ii)All material Taxes due and payable by or with respect to Wholesale and Transport (whether or not shown on any Tax Return) have been fully paid, and any material deficiencies asserted or assessments made with respect to such Tax Returns have been paid in full or properly accrued. All Taxes that Wholesale or Transport has been required by applicable law to withhold, collect or deposit have been duly withheld or collected and, to the extent required, have been paid to the appropriate Governmental Authorities.

(iii)Except with respect to an ongoing audit of Wholesale by the state of California for Tax years 2011 through 2016, no Tax Proceeding of or with respect to Wholesale or Transport is currently pending or has been proposed in writing or has been threatened that constitutes a Material Adverse Effect.

(iv)No waivers or extensions of statutes of limitations have been given or requested in writing with respect to any amount of Taxes or any Tax Returns of or with respect to Wholesale or Transport, except for a waiver executed by Wholesale for an ongoing audit by the state of California for Tax years 2011 through 2016.

(b)To MPLX’s Knowledge, for U.S. federal income Tax purposes, Wholesale is classified as an entity that is disregarded as separate from Energy and Transport is classified as an association taxable as a corporation.

(c)To MPLX’s Knowledge, none of Wholesale or Transport is a party to any Tax allocation, sharing or indemnity agreement or arrangement with any Person or has any contractual obligation to indemnify any other Person with respect to Taxes (other than pursuant to contracts entered into in the ordinary course of business the primary subject of which is not Taxes.

(d)The representations and warranties set forth in this Section 5.10 are the sole and exclusive representations of MPLX with respect to Tax matters.

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Section 5.11Environmental Matters. Except as would not, individually or in the aggregate, have a Material Adverse Effect:

(a)Wholesale, Transport, the Wholesale Assets, and the Transport Assets are in compliance with Environmental Laws;

(b)to MPLX’s Knowledge, none of Wholesale, Transport, the Wholesale Assets, or the Transport Assets is the subject of any outstanding administrative or judicial order, or any judgment, agreement or arbitration award from any Governmental Authority under any Environmental Law and requiring remediation or the payment of a fine or penalty;

(c)neither Wholesale nor Transport is subject to any pending Litigation under any Environmental Law with respect to the Wholesale Assets or the Transport Assets; and

(d)no Release into the environment of any Hazardous Substance has occurred that to MPLX’s Knowledge has resulted or could reasonably be expected to result in either Wholesale or Transport incurring any material liability under Environmental Law; and

(e)The representations and warranties set forth in this Section 5.11 are the sole and exclusive representations of MPLX with respect to environmental matters.

Section 5.12Permits. To MPLX’s Knowledge, Wholesale and Transport possess all Permits required by law, necessary for the conduct of the Wholesale Business and the Transport Business, as applicable, and the ownership and operation of the Wholesale Assets and the Transport Assets, as applicable, except where the failure to possess such Permits would not be material to the conduct of the Wholesale Business or the Transport Business, as applicable, or the ownership and operation of the Wholesale Assets or Transport Assets, as applicable, taken as a whole, as applicable; and there are no unresolved notices of violation with respect to any such Permit and each such Permit is valid, binding and in full force and effect.

Section 5.13Material Contracts.

(a)Disclosure Schedule 5.13(a) sets forth a true and complete listing of the Wholesale Material Contracts. To MPLX’s Knowledge, each Wholesale Material Contract is in full force and effect, and no party thereto is in breach or default thereunder and no event has occurred that upon receipt of notice or lapse of time or both would constitute any breach or default thereunder, except for such breaches or defaults as would not, individually or in the aggregate, constitute a Material Adverse Effect. Wholesale has not given nor received any notice of any action or intent to terminate or amend in any material respect any Wholesale Material Contract.

(b)Disclosure Schedule 5.13(b) sets forth a true and complete listing of the Transport Material Contracts. To MPLX’s Knowledge, each Transport Material Contract is in full force and effect, and no party thereto is in material breach or default thereunder and no event has occurred that upon receipt of notice or lapse of time or both would constitute any material breach or default under any Transport Material Contract. Transport has not given nor received any notice of any action or intent to terminate or amend in any material respect any Transport Material Contract.

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Section 5.14No Liabilities. To MPLX’s Knowledge, neither Wholesale nor Transport has any liabilities (whether accrued or fixed, absolute or contingent, matured or unmatured, determined or determinable or otherwise) except as set forth in the Wholesale Material Contracts and the Transport Material Contracts, as applicable.

Section 5.15No Adverse Change. Except for any actions taken by Wholesale or Transport by this Agreement, from July 30, 2019, (a) Wholesale and Transport have in all material respects operated the Wholesale Assets and Transport Assets, as applicable, in the ordinary course consistent with past practices, and (b) no fact, event, change, occurrence, development or circumstance has occurred that has had or would reasonably be expected to constitute, individually or in the aggregate, a Material Adverse Effect.

Section 5.16Employment Matters. Wholesale and Transport do not have and, to MPLX’s Knowledge, have never had, any employees, independent contractors, or consultants. Wholesale and Transport do not currently and, to MPLX’s Knowledge, have never sponsored, maintained, contributed to or had an obligation to contribute to any Plan or been a participating employer in any Plan. Neither Wholesale nor Transport has any liability, contingent or otherwise, with respect to any Plan.

Section 5.17Insurance. All insurance policies, if any, carried by or maintained for the benefit of Wholesale and Transport that directly insure Wholesale or Transport (the “Insurance Policies”) are in full force and effect, and, to MPLX’s Knowledge, the parties thereto are not in breach or default thereunder.

Section 5.18Disclaimer of Warranties. Except as expressly set forth in this Article V or in any agreement or instrument to be executed by MPLX in connection with the transactions contemplated hereby, MPLX makes no representations or warranties whatsoever and disclaims all liability and responsibility for any other representation, warranty, statement or information made or communicated (orally or in writing), including, without limitation, any opinion, information or advice that may have been provided by any officer, shareholder, director, employee, agent or consultant of MPLX or its Affiliates. EXCEPT AS SPECIFICALLY REPRESENTED AND WARRANTED IN THIS Article V, THE DISTRIBUTION OF THE WHOLESALE MEMBERSHIP INTERESTS IS ON AN “AS IS” BASIS, AND MPLX DISCLAIMS ANY WARRANTY OF MERCHANTABILITY AND ANY WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE.

ARTICLE VIREPRESENTATIONS AND WARRANTIES OF WRS

WRS represents and warrants as of the date hereof as follows:

Section 6.1Organization. WRS is a corporation duly organized, validly existing and in good standing under the laws of the State of Arizona and is qualified to do business in each jurisdiction where the nature of its business or the ownership of its properties requires it to be qualified, except to the extent that the failure to be so qualified would not have a Material Adverse

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Effect. WRS has the corporate power to conduct its business as presently conducted and to own and hold the properties used in connection therewith.

Section 6.2Ownership. WRS has good and valid record and beneficial title to the MPLX Common Units, free and clear of any and all Liens, and except as provided or created by the Organizational Documents of MPLX, the 1933 Act or applicable state securities laws, the MPLX Common Units are free and clear of any restrictions on transfer, Taxes, or claims.

Section 6.3Authority and Action. WRS has the corporate power and authority to enter into this Agreement and each agreement and instrument to be executed and delivered by WRS pursuant hereto and to perform all of its obligations and consummate the transactions contemplated hereby and thereby. WRS has taken all necessary and appropriate corporate action to authorize, execute and deliver this Agreement and each agreement and instrument to be executed and delivered by WRS pursuant hereto and to consummate the transactions contemplated hereby and thereby. This Agreement has been, and each agreement and instrument to be executed and delivered by WRS pursuant hereto will be when so executed and delivered, duly and validly executed and delivered by WRS and constitutes or when so executed will constitute a valid and binding obligation of WRS, enforceable in accordance with its terms, except as such enforcement may be limited by applicable bankruptcy, insolvency, moratorium or similar laws affecting the rights of creditors generally and by general principles of equity.

Section 6.4Consents. No consent, approval, license, permit, order, waiver, or authorization of, or registration, declaration, or filing with, any Governmental Authority or other Person is required to be obtained or made by or with respect to WRS in connection with:

(a)the execution, delivery, and performance of this Agreement (or any related instrument or agreement), or the consummation of the transactions contemplated hereby and thereby;

(b)the enforcement against WRS of its obligations hereunder and thereunder; or

(c)the redemption by MPLX of the MPLX Common Units;

except, in each case, as would not have, individually or in the aggregate, a Material Adverse Effect or result in any material loss, cost or liability of MPLX or its Subsidiaries.

Section 6.5No Violation. The execution and delivery of this Agreement (or any related instrument or agreement to be executed and delivered) by WRS does not, or when executed will not, and the consummation of the transactions contemplated hereby or thereby and the performance by WRS of the obligations that it is obligated to perform hereunder or thereunder do not:

(a)conflict with or result in a breach of any of the provisions of any Organizational Documents of WRS;

(b)result in the creation, violation or acceleration of, or afford any Person the right to obtain or accelerate any obligation or indebtedness under, any Lien on the property or assets of WRS;

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(c)conflict with any municipal, state or federal ordinance, law (including common law), rule, regulation, judgment, order, writ, injunction, or decree applicable to WRS; or

(d)conflict with, result in a breach of, constitute a default under (whether with notice or the lapse of time or both) or accelerate or permit the acceleration of the performance required by, or require any consent, authorization or approval under, any indenture, mortgage, lien or agreement, contract, commitment or instrument to which WRS is a party or by which it is bound;

except, in the case of clauses (b), (c) and (d), as would not have, individually or in the aggregate, a Material Adverse Effect or result in any material loss, cost or liability of MPLX or its Subsidiaries.

Section 6.6Disclaimer of Warranties. Except as expressly set forth in this Article VI or in any agreement or instrument to be executed by WRS in connection with the transactions contemplated hereby, WRS makes no representations or warranties whatsoever and disclaims all liability and responsibility for any other representation, warranty, statement or information made or communicated (orally or in writing), including, without limitation, any opinion, information or advice that may have been provided by any officer, shareholder, director, employee, agent or consultant of WRS, or its Affiliates.

ARTICLE VII

COVENANTS

Section 7.1Further Assurances. In case at any time after the Closing any further action is necessary to carry out the purposes of this Agreement, each of the Parties will take such further action as the other Parties reasonably may request, all at the sole cost and expense of the requesting Party (unless the requesting Party is entitled to indemnification therefor).

Section 7.2Tax Covenants.

(a)Transaction Taxes. All sales, use, controlling interest, transfer, filing, recordation, registration and similar Taxes arising from or associated with the transactions contemplated by this Agreement, other than Taxes based on income or net worth (“Transaction Taxes”), shall be borne fifty percent (50%) by WRS and fifty percent (50%) by MPLX. Except to the extent required by applicable law, MPLX shall prepare and file all Tax Returns in respect of Transaction Taxes. The Parties shall reasonably cooperate in good faith to minimize, to the extent permissible under laws, the amount of any such Transaction Taxes. Each Party will provide and make available to each other Party any resale certificates and other exemption certificates or information reasonably requested by such other Party.

(b)Pre-Closing Tax Returns. MPLX will cause to be prepared each Tax Return of Wholesale and Transport for a Pre-Closing Tax Period that is required to be filed after the Closing Date (each, a “Pre-Closing Tax Return”). At least thirty (30) days prior to the due date for filing such Pre-Closing Tax Return, MPLX will deliver a copy of such Pre-Closing Tax Return, together with all supporting documentation and workpapers, to WRS for its review and comment. WRS shall provide any comments to any such draft Tax Return no later than fifteen (15) days after receipt of such draft from MPLX, and MPLX will revise such Pre-Closing Tax Return to reflect any reasonable

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comments timely received from WRS. Not later than five (5) days prior to the due date for filing such Pre-Closing Tax Return, MPLX will provide such revised Pre-Closing Tax Return to WRS for filing by WRS with the appropriate Governmental Authority. Not later than five (5) days prior to the due date for payment of Taxes with respect to such Pre-Closing Tax Return, MPLX will pay to WRS the amount of any Energy Taxes with respect to such Pre-Closing Tax Return.

(c)Straddle Period Tax Returns. WRS will prepare or cause to be prepared each Tax Return of Wholesale and Transport for a Straddle Period (each, a “Straddle Tax Return”). Not later than thirty (30) days prior to the due date for filing such Straddle Tax Return, WRS will deliver a copy of such Straddle Tax Return (other than Tax Returns relating to sales, use, payroll, or other Taxes that are required to be filed contemporaneously with, or promptly after, the close of a taxable period, in each case a copy of which shall be provided to MPLX by WRS upon MPLX’s written request), together with all supporting documentation and workpapers, to MPLX for its review and comment. MPLX shall provide any comments to any such draft Tax Return no later than fifteen (15) days after receipt of such draft from WRS, and WRS will cause such Straddle Tax Return (as revised to reflect any reasonable comments timely received MPLX) to be filed timely with the appropriate Governmental Authority and will provide a copy to MPLX. Not later than five (5) days prior to the due date for payment of with respect to such Straddle Tax Return, MPLX will pay to WRS the amount of any Energy Taxes with respect to such Straddle Tax Return.

(d)Proration of Straddle Period Taxes. In the case of Taxes that are payable with respect to any Straddle Period, the portion of any such Taxes that is attributable to the portion of such Straddle Period ending on the Closing Date shall be:

(i)in the case of Taxes that are imposed on a periodic basis with respect to the assets or capital of Wholesale or Transport, deemed to be the amount of such Taxes for the entire Straddle Period (or, in the case of such Taxes determined on an arrears basis, the amount of such Taxes for the immediately preceding period), multiplied by a fraction the numerator of which is the number of calendar days in the portion of such Straddle Period ending on and including the Closing Date and the denominator of which is the number of calendar days in the entire Straddle Period; and

(ii)in the case of all other Taxes, deemed equal to the amount which would be payable if the relevant Straddle Period ended on and included the Closing Date; provided that exemptions, allowances, or deductions that are calculated on an annual basis (including depreciation and amortization deductions) shall be allocated between the portion of the Straddle Period ending on and including the Closing Date and the portion of the Straddle Period beginning after the Closing Date in proportion to the number of days in each portion of such Straddle Period.

(iii)Notwithstanding anything to the contrary herein, any franchise Tax will be allocated to the period during which the income, operations, assets or capital comprising the base of such Tax is measured, regardless of whether the right to do business for another period is obtained by the payment of such franchise Tax.

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(e)Tax Refunds. Any refunds of Taxes of Wholesale or Transport (whether in the form of cash received or a credit or offset actually realized against Taxes otherwise payable) (“Tax Refunds”) for any Pre-Closing Tax Period shall be for the account of MPLX. Any Tax Refunds for any Tax period beginning after the Closing Date shall be for the account of WRS. Any Tax Refunds for any Straddle Period shall be equitably apportioned between MPLX and WRS in accordance with the principles provided for in Section 7.2(d). To the extent that WRS or Wholesale or Transport receives a Tax Refund that is for the account of MPLX pursuant to this Section 7.2(e), WRS shall pay the amount of such Tax Refund (and any interest received from the Governmental Authority), net of any reasonable out-of-pocket costs or expenses incurred by WRS or its Affiliates in procuring such refund, to MPLX. To the extent that MPLX receives a Tax Refund that is for the account of WRS pursuant to this Section 7.2(e), MPLX shall pay the amount of such Tax Refund (and any interest received from the Governmental Authority), net of any reasonable out-of-pocket costs or expenses incurred by MPLX or its Affiliates in procuring such refund, to WRS. The amount due to MPLX or WRS, as applicable, under this Section 7.2(e) shall be paid to the MPLX or WRS, as applicable, within thirty (30) days of the receipt of the Tax Refund from the applicable Governmental Authority (or, if the Tax Refund is in the form of a credit or offset against Taxes otherwise payable, within thirty (30) days after the due date of the Tax Return claiming such credit or offset).

(f)Tax Characterization. The Parties intend that, for U.S. federal (and applicable state and local) income tax purposes, the Transfer be treated as a distribution by MPLX pursuant to Section 731 of the Code and not as a sale of the Wholesale Membership Interests (or the Wholesale Assets). The Parties (and each such Party’s Affiliates) will prepare and file all Tax Returns consistent with the foregoing and will not take any position for Tax purposes inconsistent with the foregoing, except as otherwise required by applicable law or a final determination as defined in Section 1313 of the Code.

Section 7.3Conflicts. In the event of a conflict between the provisions of this Article VII and any other provision of this Agreement, the provisions of this Article VII shall control.

Section 7.4Post-Closing Payment for Services. With regard to the accounts receivable balance for certain fuel supply transactions as of July 31, 2020 between Wholesale; Speedway LLC; Western Refining Retail, LLC; Giant Four Corners, LLC; and Giant Stop-n-Go of New Mexico, LLC (the “Supply Payment”), WRS shall cause Wholesale to remit the Supply Payment, when received after the Closing, to Energy or to such other party as designated in writing by Energy, or Wholesale may direct Speedway LLC to remit the Supply Payment to Energy or to such other party as designated in writing by Energy.

Section 7.5Second Quarter 2020 Distribution. For the avoidance of doubt, notwithstanding anything in MPLX’s Organizational Documents to the contrary, neither WRS nor any of its Affiliates shall be entitled to receive any distribution from MPLX for the fiscal quarter ended June 30, 2020 with respect to the MPLX Common Units.

Section 7.6Sale Proceeds. If, following the Closing Date but on or before the date that is twelve months after the Closing Date, a Trigger Event occurs, WRS shall pay to MPLX, as

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additional consideration for the Membership Interests, an amount in cash equal to 75% of the sum of (a) the amount of Sale Proceeds received or deemed received by WRS and its Affiliates in respect of such Trigger Event less (b) the Total Value. Any such amount due to MPLX hereunder shall be paid no later than the closing date of the applicable Trigger Event.

ARTICLE VIII

CLOSING

The Closing of this Agreement shall be conducted as follows, with the performance of the Parties to be mutually dependent, and all transfers deemed to have taken place simultaneously:

Section 8.1Closing. The Closing of the transactions contemplated by this Agreement shall occur on July 31, 2020 (the “Closing Date”). The transactions contemplated by this Agreement shall be deemed to be effective at the Effective Time in the order set forth in this Agreement.

Section 8.2Deliveries by MPLX to WRS. At Closing, MPLX shall deliver to WRS:

(a)an Assignment and Assumption Agreement substantially in the form of Exhibit 2 duly executed by MPLX;

(b)appropriate resolutions and other similar documents of MPLX, to fully implement this Agreement;

(c)a properly executed certificate of MPLX certifying that MPLX is not a “foreign person” within the meaning of Section 1445 of the Code; and

(d)each other document or instrument specified in or as may be reasonably required by this Agreement.

Section 8.3Deliveries by WRS to MPLX. At Closing, WRS shall deliver to MPLX:

(a)appropriate resolutions and other similar documents of WRS, to fully implement this Agreement;

(b)a properly executed certificate of WRS certifying that WRS is not a “foreign person” within the meaning of Section 1445 and 1446(f) of the Code; and

(c)each other document or instrument specified in or as may be reasonably required by this Agreement.

ARTICLE IX

MISCELLANEOUS

Section 9.1Assigns. This Agreement shall be binding upon and shall inure to the benefit of the respective Parties and their permitted successors and assigns. A Party’s rights under this Agreement may not be assigned without the prior written consent of all other Parties, which consent may be withheld for any reason. Any purported assignment in violation of the foregoing shall be void ab initio.

Section 9.2Entire Understanding, Headings and Amendment.

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(a)This entire Agreement and the attached Annexes, Exhibits and Disclosure Schedules and all documents to be executed and delivered pursuant hereto constitute the entire understanding among the Parties, and supersede all previous agreements of any sort. EACH PARTY HERETO AGREES THAT, EXCEPT FOR THE REPRESENTATIONS AND WARRANTIES CONTAINED IN THIS AGREEMENT, NEITHER OF THE PARTIES MAKES OR RELIES ON ANY OTHER REPRESENTATIONS, WARRANTIES OR INDUCEMENTS, AND EACH HEREBY DISCLAIMS ANY OTHER REPRESENTATIONS, WARRANTIES OR INDUCEMENTS, EXPRESS OR IMPLIED, AS TO THE ACCURACY OR COMPLETENESS OF ANY OTHER INFORMATION, MADE BY, OR MADE AVAILABLE BY, ITSELF OR ANY OF ITS REPRESENTATIVES, WITH RESPECT TO, OR IN CONNECTION WITH, THE NEGOTIATION, EXECUTION OR DELIVERY OF THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED BY THIS AGREEMENT, NOTWITHSTANDING THE DELIVERY OR DISCLOSURE TO THE OTHER OR THE OTHER’S REPRESENTATIVES OF ANY DOCUMENTATION OR OTHER INFORMATION WITH RESPECT TO ANY ONE OR MORE OF THE FOREGOING. No Party shall be bound by, or be liable for, any alleged representation, promise, inducement or statement of intention not contained herein. Article headings are included only for purposes of convenience and shall not be construed as a part of this Agreement or in any way affecting the meaning of the provisions of this Agreement or its interpretation.

(b)None of this Agreement or any Ancillary Agreement may be amended or modified orally, and no amendment or modification of this Agreement or any Ancillary Agreement shall be valid unless in writing and signed by the Parties; provided, any such amendment or modification must be approved by the Conflicts Committee.

Section 9.3Rights of Third Parties. This Agreement shall not be construed to create any lien or encumbrance on the Membership Interests, or to create any express or implied rights in any Person other than the Parties, except as expressly provided with respect to the WRS Indemnitees and the MPLX Indemnitees in Article IV.

Section 9.4Notices. All notices shall be in writing and shall be delivered or sent by first‑class mail, postage prepaid, overnight courier or by means of electronic transmission. Any notice sent shall be addressed as follows:

(a)If to WRS:

Western Refining Southwest, Inc.

539 South Main Street

Findlay, Ohio 45840

Attn: President

With copy (which shall not constitute notice) to:

Marathon Petroleum Company LP

539 South Main Street

Findlay, Ohio 45840

Attn: General Counsel

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(b)If to MPLX:

MPLX LP

200 East Hardin Street

Findlay, Ohio 45840

Attn: General Counsel

Any notice required hereunder shall be effective when sent if given in the manner set forth above.

Section 9.5Choice of Law; Mediation; Submission to Jurisdiction; Waiver of Jury Trial.

(a)This Agreement and all the Ancillary Agreements shall be subject to and governed by the laws of the State of Delaware, excluding any conflicts-of-law rule or principle that might refer the construction or interpretation of this Agreement to the laws of another state. EACH OF THE PARTIES AGREES THAT THIS AGREEMENT INVOLVES AT LEAST U.S. $100,000.00 AND THAT THIS AGREEMENT HAS BEEN ENTERED INTO IN EXPRESS RELIANCE UPON 6 Del. C. § 2708. EACH OF THE PARTIES IRREVOCABLY AND UNCONDITIONALLY AGREES (i) TO BE SUBJECT TO THE JURISDICTION OF THE COURTS OF THE STATE OF DELAWARE AND OF THE FEDERAL COURTS SITTING IN THE STATE OF DELAWARE, AND (ii) TO THE EXTENT SUCH PARTY IS NOT OTHERWISE SUBJECT TO SERVICE OF PROCESS IN THE STATE OF DELAWARE, TO APPOINT AND MAINTAIN AN AGENT IN THE STATE OF DELAWARE AS SUCH PARTY’S AGENT FOR ACCEPTANCE OF LEGAL PROCESS AND TO NOTIFY THE OTHER PARTIES OF THE NAME AND ADDRESS OF SUCH AGENT.

(b)If the Parties cannot resolve any dispute or claim arising under this Agreement, then no earlier than ten (10) days nor more than sixty (60) days following written notice to the other Parties, any Party to such dispute or claim may initiate mandatory, non-binding mediation hereunder by giving a notice of mediation (a “Mediation Notice”) to the other Parties. In connection with any mediation pursuant to this Section 9.5(b), the mediator shall be jointly appointed by the Parties and the mediation shall be conducted in Findlay, Ohio unless otherwise agreed by the Parties. All costs and expenses of the mediator appointed pursuant to this Section 9.5(b) shall be shared equally and paid by the Parties. The then-current Model ADR Procedures for Mediation of Business Disputes of the Center for Public Resources, Inc., either as written or as modified by mutual agreement of the Parties, shall govern any mediation pursuant to this Section 9.5(b). In the mediation, each Party shall be represented by one or more senior representatives who shall have authority to resolve any disputes. If a dispute or claim has not been resolved within thirty (30) days after the receipt of the Mediation Notice by a Party, then any Party may refer the resolution of the dispute or claim to litigation.

(c)Subject to Section 9.5(b), each Party agrees that it shall bring any action or proceeding in respect of any claim arising out of or related to this Agreement, whether in tort or contract or at law or in equity, exclusively in any federal or state courts located in Delaware and (i) waives any objection to laying venue in any such action or proceeding in such courts; (ii) waives any objection that such courts are an inconvenient forum or do not have jurisdiction over it; and (iii) agrees that,

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to the fullest extent permitted by law, service of process upon it may be effected by mailing a copy thereof by registered or certified mail (or any substantially similar form of mail), postage prepaid, to it at its address specified in Section 9.4. The foregoing consents to jurisdiction and service of process shall not constitute general consents to service of process in the State of Delaware for any purpose except as provided herein and shall not be deemed to confer rights on any Person other than the Parties.

(d)EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH MAY ARISE UNDER THIS AGREEMENT IS LIKELY TO INVOLVE COMPLICATED AND DIFFICULT ISSUES, AND THEREFORE EACH SUCH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY RIGHT SUCH PARTY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY ACTION OR PROCEEDING DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS AGREEMENT, OR THE TRANSACTIONS CONTEMPLATED BY THIS AGREEMENT. EACH PARTY CERTIFIES AND ACKNOWLEDGES THAT (i) NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF ANY ACTION OR PROCEEDING, SEEK TO ENFORCE THE FOREGOING WAIVER, (ii) EACH PARTY UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THIS WAIVER, (iii) EACH PARTY MAKES THIS WAIVER VOLUNTARILY, AND (iv) EACH PARTY HAS BEEN INDUCED TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 9.5(d).

Section 9.6Time of the Essence. Time is of the essence in the performance of this Agreement in all respects. If the date specified herein for giving any notice or taking any action is not a business day (or if the period during which any notice is required to be given or any taken expires on a date which is not a business day), then the date for giving such notice or taking such action (and the expiration date of such period during which notice is required to be given or action taken) shall be the next day which is a business day.

Section 9.7Waiver and Severability.

(a)No waiver, either express or implied, by any Party hereto of any term or condition of this Agreement or right to enforcement thereof shall be effective, unless such waiver is in writing and signed by all Parties. Any such waiver shall constitute a waiver only with respect to the specific matter described in such writing and shall in no way adversely affect the rights of the Parties granting such waiver in any other respect or at any other time. The failure of any Party to exercise any rights or privileges under this Agreement shall not be construed as a waiver of any such rights or privileges under this Agreement. The rights and remedies provided in this Agreement are cumulative and, except as otherwise expressly provided in this Agreement, none is exclusive of any other or of any rights or remedies that any Party may hereunder or otherwise have at law or in equity.

(b)Whenever possible, each provision or portion of any provision of this Agreement shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision or portion of any provision of this Agreement is held to be invalid, illegal or unenforceable

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in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality or unenforceability shall not affect any other provision or portion of any provision in such jurisdiction, and this Agreement shall be reformed, construed and enforced in such jurisdiction as if such invalid, illegal or unenforceable provision or portion of any provision had never been contained herein.

Section 9.8Costs and Expenses. Except as otherwise specifically provided in this Agreement, each Party will bear its own costs and expenses in connection with this Agreement and the transactions contemplated hereby.

Section 9.9Counterpart Execution. This Agreement may be executed in counterparts, each of which shall be deemed an original, but all of which together shall constitute one agreement.

Section 9.10Deed; Bill of Sale; Assignment. To the extent required and permitted by applicable law, this Agreement shall also constitute a “deed,” “bill of sale” or “assignment” of the assets and the liabilities referenced herein.

[Signature page follows.]

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IN WITNESS WHEREOF, each of the Parties has caused this Agreement to be executed as of the date first set forth above.

Western Refining Southwest, Inc.
By:	/s/ Donald C. Templin
Name:	Donald C. Templin
Title:	Vice President
MPLX LP
By:	MPLX GP LLC, its General Partner
By:	/s/ Pamela K.M. Beall
Name:	Pamela K.M. Beall
Title:	Executive Vice President and Chief Financial Officer

APPENDIX A

DEFINITION OF TERMS

Introductory Note—Construction. Whenever the context requires, the gender of all words used in the Agreement includes the masculine, feminine and neuter and terms defined in the singular have the corresponding meanings in the plural, and vice versa. Except as the Agreement otherwise specifies, all references herein to any law, are references to that law (and any rules and regulations promulgated thereunder), as the same may have been amended. The word “includes” or “including” means “including, but not limited to,” unless the context otherwise requires. The words “shall” and “will” are used interchangeably and have the same meaning. The words “this Agreement,” “hereof,” “hereby,” “herein,” “hereunder” and similar terms in the Agreement refer to the relevant agreement as a whole and not any particular Section or Article in which such words appear. If a word or phrase is defined, its other grammatical forms have a corresponding meaning. Whenever the Agreement refers to a number of days, such number shall refer to calendar days unless business days are specified. Time periods within or following which any payment is to be made or an act is to be done shall be calculated by excluding the day on which the time period commences and including the day on which the time period ends. Unless specifically provided for in this Agreement, the term “or” shall not be deemed to be exclusive. References to a Person are also to its successors and/or permitted assigns, if any. All exhibits and annexes attached to this Agreement constitute a part of this Agreement and are incorporated herein for all purposes. All references to currency in this Agreement shall be to, and all payments required under this Agreement shall be paid in, lawful currency of the United States.

Definitions.

“1933 Act” means the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder.

“Affiliate” means, as to any specified entity, any other entity that, directly or indirectly through one or more intermediaries or otherwise, controls, is controlled by or is under common control with the specified entity. For purposes of this Agreement, “control” of an entity means the possession, directly or indirectly, of the power to direct or cause the direction of the management or policies of such entity, whether by contract or otherwise. Notwithstanding anything herein to the contrary, for purposes of this Agreement, (a) WRS and its Subsidiaries (including, from and after the Closing, Wholesale and Transport) shall be deemed not to be “Affiliates” of MPLX (or, prior to the Closing, Wholesale and Transport), or any of its Subsidiaries, and (b) MPLX and its Subsidiaries (including, prior to the Closing, Wholesale and Transport) shall not be deemed “Affiliates” of WRS and its Subsidiaries (including, from and after the Closing, Wholesale and Transport).

“Agreement” has the meaning set forth in the preamble.

“Ancillary Agreement” means all of the agreements set forth in the exhibits to this Agreement.

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“ANDX” has the meaning set forth in the recitals.

“Cap” means $34,000,000.

“Closing” means the consummation of the transactions contemplated by this Agreement.

“Closing Date” has the meaning set forth in Section 8.1.

“Code” means the United States Internal Revenue Code of 1986, as amended.

“Common Unit” has the meaning set forth in the MPLX Partnership Agreement.

“Conflicts Committee” means the Conflicts Committee of the Board of Directors of MPLX GP LLC, the general partner of MPLX.

“Contract” means any contract, commitment, instrument, undertaking, lease, note, mortgage, indenture, settlement, Permit, or other legally binding agreement.

“Deductible” means $1,700,000.

“DLLCA” means that Delaware Limited Liability Company Act, as amended.

“Effective Time” means 11:59 pm local time in Findlay, Ohio on the Closing Date.

“Energy” has the meaning set forth in the recitals.

“Energy GP” has the meaning set forth in the recitals.

“Energy Taxes” means any and all Taxes (a) imposed on Energy or MPLX attributable to Wholesale or Transport (including assets of Wholesale or Transport), or imposed on Wholesale or Transport, or for which Wholesale or Transport may otherwise be liable, for any Pre-Closing Tax Period and for the portion of any Straddle Period ending on and including the Closing Date (determined in accordance with Section 7.2(d)); (b) of any affiliated, combined, consolidated, unitary or similar group with respect to any Taxes of which Wholesale or Transport (or any predecessor of Wholesale or Transport) is or was a member on or prior to the Closing Date by reason of Treasury Regulations § 1.1502-6(a) or any analogous or similar foreign, state or local law; and (c) of any other Person for which any member of the Wholesale or Transport is or has been liable as a transferee or successor, by contract, or otherwise.

“Environmental Laws” means any and all applicable federal, state or local law or statute, or regulations promulgated thereunder, together with any amendments thereto and all substitutions thereof, concerning the environment, preservation or reclamation of natural resources, natural resource damages, human health and safety, prevention or control of spills or pollution, or to the management (including without limitation generation, treatment, storage, transportation, arrangement for transport, disposal, arrangement for disposal or other handling), Release or threatened Release of Hazardous Substances, including without limitation, the Clean Water Act, also known as the Federal Water Pollution Control Act, 33 U.S.C. § 1251 et. seq., the Oil Pollution Act of 1990, 33 U.S.C. § 2701 et. seq., the Toxic Substances Control Act, 15 U.S.C. § 2601 et. seq.,

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the Comprehensive Environmental Response, Compensation and Liability Act, 42 U.S.C. § 9601 et. seq., the Superfund Amendment and Reauthorization Act of 1986, Public Law 99- 499, 100 Stat. 1613, the Emergency Planning and Community Right to Know Act, 42 U.S.C. § 1101 et. seq., the Resource Conservation and Recovery Act, 42 U.S.C. § 6901 et. seq., the Occupational Safety and Health Act, as amended, 29 U.S.C. § 655 and § 657, the Clean Air Act, 42 U.S.C, § 7401 et. seq., the Safe Drinking Water Act, 42 U.S.C. § 300f to § 300j-26, the Hazardous Materials Transportation Authorization Act of 1994, 49 U.S.C. § 5101 et. seq., the Atomic Energy Act of 1954 as amended, 42 U.S.C. §§ 2014, 2021(d), 2022, 2111, 2113 and 2114.

“Equity Interest” means capital stock, voting securities, partnership or membership interests or units (whether general or limited), and any other interest or participation that confers on a Person the right to receive a share of the profits and losses of the issuing entity.

“Execution Date” means the date of this Agreement.

“Fundamental Representations” has the meaning set forth in Section 4.3(a).

“Governmental Authority” means any federal, state, local, foreign, multi-national, supra‑national, national, regional or other governmental agency, authority, administrative agency, regulatory body, commission, board, bureau, agency, officer, official, instrumentality, court or arbitral tribunal having governmental or quasi-governmental powers or any other instrumentality or political subdivision thereof; provided, however, that such term shall not include any entity or organization that is engaged in industrial or commercial operations and is wholly or partly owned by any government, to the extent that such entity or organization is acting in a commercial capacity.

“Hazardous Substance” means any substance, material or waste designated, regulated or classified as a hazardous waste, hazardous substance, hazardous material, pollutant, contaminant or toxic substance under any Environmental Law, including petroleum or petroleum distillates, asbestos or asbestos-containing materials, polychlorinated biphenyls, radon gas, radioactive materials or wastes, and infectious or medical wastes.

“Indemnified Party” has the meaning set forth in Section 4.4.

“Indemnifying Party” has the meaning set forth in Section 4.4.

“Insurance Policies” has the meaning set forth in Section 5.17.

“Knowledge” means the actual knowledge of Pamela K.M. Beall.

“Liens” means any security interest, lien, deed of trust, mortgage, pledge, charge, restriction, easement, encumbrance or other similar interest or right.

“Litigation” has the meaning set forth in Section 5.8.

“Logistics” has the meaning set forth in the recitals.

“Losses” has the meaning set forth in Section 4.1(a).

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“Material Adverse Effect” means any change, circumstance, effect or condition that is, or could reasonably be expected to be, individually or in the aggregate, materially adverse to (i) the business, financial condition, assets, liabilities or results of operations of Wholesale and Transport, taken as a whole, or the Wholesale Business and the Transport Business, taken as a whole; or (ii) any Party’s ability to enter into or perform its obligations under this Agreement or to consummate the transactions contemplated hereby; provided, that the term “Material Adverse Effect” shall not include:

(a)any fact, change, effect, condition or event that:

(i)generally affects economic conditions in any of the markets or geographical areas in which Wholesale and Transport operate;

(ii)generally affects economic conditions or the financial, banking, currency or capital markets in general (whether in the United States or any other country or in any international market), including changes in (1) general financial or market conditions, (2) currency exchange rates or currency fluctuations, (3) prevailing interest rates or credit markets, and (4) the price of commodities or raw materials used in the businesses of Wholesale or Transport;

(iii)generally affect the industries in which Wholesale and Transport operate; or

(iv)result from national or international political or social actions or conditions, including the engagement by any country in hostilities, whether commenced before or after the date hereof, and whether or not pursuant to the declaration of a national emergency or war, or the occurrence of any military or terrorist attack;

(b)changes in law, GAAP or other applicable accounting standards or interpretations thereof;

(c)any failure to meet internal projections, public estimates or expectations with respect to Wholesale or Transport (it being understood that the underlying causes of any such failure may be taken into consideration in determining whether a Material Adverse Effect has occurred); or

(d)the announcement of, or the taking of any action contemplated by, this Agreement and the other agreements contemplated hereby; provided, however, that facts, changes, affects, conditions or events referred to in clauses (a)(i), (a)(ii), (a)(iii), (a)(iv) and (b) above shall be considered for purposes of determining whether there has been or would reasonably be expected to be a Material Adverse Effect if and only to the extent such facts, changes, affects, conditions or events have had or would reasonably be expected to have a disproportionate effect on Wholesale or Transport as compared to other companies operating in similar businesses.

“Mediation Notice” had the meaning set forth in Section 9.5(b).

“Membership Interests” has the meaning set forth in the recitals.

“MPLX” has the meaning set forth in the preamble.

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“MPLX Common Units” has the meaning set forth in Section 3.1.

“MPLX Indemnitee” has the meaning set forth in Section 4.2.

“MPLX Partnership Agreement” means the Fifth Amended and Restated Agreement of Limited Partnership of MPLX dated July 30, 2019, including any and all amendments thereof.

“NYSE” means the New York Stock Exchange.

“Organizational Document” means, with respect to any entity, the legal organizational and governing documents of such entity, including the certificate of incorporation, certificate of formation, certificate of limited partnership, bylaws, limited liability company agreement, operating agreement, agreement of limited partnership or shareholders’ agreement, in each case, as currently in effect.

“Parties” and “Party” have the meaning set forth in the preamble.

“Permit” means permits, licenses, certificates, orders, approvals, authorization, grants, consents, concessions, warrants, franchises and similar rights and privileges.

“Permitted Lien” means:

(a)inchoate liens and charges imposed by law (including with respect to Taxes), Taxes, assessments, obligations under workers’ compensation, unemployment insurance or other social welfare legislation or other requirements, charges or levies of any Governmental Authority, in each case not yet delinquent and that will be paid by each of Wholesale and Transport, as applicable, in the ordinary course of business, or the validity or amount of which is being contested in good faith by Wholesale or Transport, provided, that such contesting entity shall be responsible for, and shall promptly pay when due, including any interest and penalties, all amounts finally determined to be owed that are the subject of such contest;

(b)easements, servitudes, leases, rights­of­way and other rights, exceptions, reservations, conditions, limitations, covenants and other restrictions or encumbrances that are recorded in the public records or reflected on the final survey, and in all cases that do not materially interfere with or impact WRS’s intended use of the Wholesale Assets or the Transport Assets;

(c)any liens consisting of (A) statutory landlord’s liens under leases which Wholesale or Transport is a party or other liens on leased property reserved in leases thereof for rent or for compliance with the terms of such leases, (B) rights reserved to or vested in any Governmental Authority to control or regulate any property of Wholesale or Transport or to limit the use of such property in any manner which does not materially impair the use of such property, (C) obligations or duties to any Governmental Authority with respect to any franchise, grant, license, lease or permit and the rights reserved or vested in any Governmental Authority to terminate any such franchise, grant, license, lease or permit or to condemn or expropriate any property, or (D) zoning or other land use or Environmental Laws and ordinances of any Governmental Authority, in each case that arise in the ordinary course of business and that do not interfere with the ordinary conduct of the

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business by Wholesale or Transport at such property; provided, that such Party shall be responsible for, and shall promptly pay when due, including any interest and penalties, all amounts finally determined to be owed that are the subject of such contest; and

(d)liens of carriers, warehousemen, mechanics, laborers and materialmen and similar charges that arise in the ordinary course of business, and that are either not filed of record and not delinquent or that are filed of record but are being contested in good faith by Wholesale or Transport; provided, that such Party shall be responsible for, and shall promptly pay when due, including any interest and penalties, all amounts finally determined to be owed that are the subject of such contest.

“Person” means any natural person, corporation, general partnership, limited partnership, limited liability company, unlimited liability corporation, proprietorship, other business organization, trust, union, association or Governmental Authority.

“Plan” means, whether written or oral, each “employee benefit plan” within the meaning of Section 3(3) of ERISA (including “multiemployer plans” within the meaning of Section 3(37) of ERISA) (whether or not subject to ERISA) and any and all employment, deferred compensation, change in control, severance, termination, loan, employee benefit, retention, bonus, pension, profit sharing, savings, retirement, welfare, incentive compensation, stock or equity-based compensation, stock purchase, stock appreciation, collective bargaining, fringe benefit, vacation, paid time off, sick leave or other similar agreements, plans, programs, policies, understandings or arrangements.

“Pre-Closing Tax Period” means any taxable period ending on or before the Closing Date.

“Pre-Closing Tax Return” has the meaning set forth in Section 7.2(b).

“Release” means any depositing, spilling, leaking, pumping, pouring, placing, emitting, discarding, abandoning, emptying, discharging, migrating, injecting, escaping, leaching, dumping or disposing of any Hazardous Substance into the environment.

“Sale Proceeds” means the aggregate value of all consideration (cash and non-cash) received or deemed to be received by WRS or its Affiliates, solely with respect to the Transport Business and/or the Wholesale Business, in respect of a Trigger Event.

“Straddle Period” means any Tax period beginning on or before and ending after the Closing Date.

“Straddle Tax Return” has the meaning set forth in Section 7.2(c).

“Subsidiary” means, with respect to any Person, (a) a corporation of which more than 50% of the voting power of shares entitled (without regard to the occurrence of any contingency) to vote in the election of directors or other governing body of such corporation is owned, directly or indirectly, at the date of determination, by such Person, by one or more Subsidiaries of such Person or a combination thereof, (b) a partnership (whether general or limited) in which such Person or a Subsidiary of such Person is, at the date of determination, a general or limited partner of such partnership, but only if more than 50% of the general partner interests of such partnership is owned,

6

directly or indirectly, at the date of determination, by such Person, by one or more Subsidiaries of such Person, or a combination thereof; or (c) any other Person (other than a corporation or a partnership) in which such Person, one or more subsidiaries of such Person, or a combination thereof, directly or indirectly, at the date of determination, has (i) at least a majority ownership interest or (ii) the power to elect or direct the election of a majority of the directors or other governing body of such Person.

“Supply Payment” has the meaning set forth in Section 7.4.

“Tax” means (i) any and all federal, state, provincial, county, local or foreign taxes or levies of any kind and any and all other like assessments, customs, duties, imposts, charges or fees, including income, gross receipts, ad valorem, value added, excise, real property, personal property, escheat, asset, sales, use, franchise, license, payroll, transaction, capital, capital gains, net worth, withholding, estimated, social security, utility, workers’ compensation, severance, disability, wage, employment, production, unemployment compensation, occupation, premium, windfall profits, transfer, gains, alternative or add-on minimum, stamp, documentary, recapture, business license, business organization, environmental, profits, lease, or other taxes or other charges imposed by or on behalf or payable to any Governmental Authority including tax liabilities arising under Treasury Regulation Section 1.1502-6 and any similar provisions from federal, state, local or foreign applicable law, together with any interest, fines, penalties, assessments, or additions resulting from, attributable to, or incurred in connection with any of the foregoing (whether or not disputed) and (ii) any transferee or other secondary or non-primary liability or other obligations with respect to any item in clause (i) above, whether such liability or obligation arises by assumption, operation of law, contract, indemnity, guarantee, as a successor or otherwise.

“Tax Refund” has the meaning set forth in Section 7.2(e).

“Tax Return” means any report, statement, form, return or other document or information required to be supplied to a Governmental Authority having jurisdiction over the payment or reporting of any Tax.

“Tax Proceeding” means any action, audit, litigation or other proceeding for assessment or collection of Taxes.

“Third Party Claim” has the meaning set forth in Exhibit 1.

“Transaction Taxes” has the meaning set forth in Section 7.2(a).

“Transport” has the meaning set forth in the recitals.

“Transport Membership Interests” has the meaning set forth in the recitals.

“Transfer” has the meaning set forth inSection 2.1

“Transport Assets” has the meaning set forth in Section 5.9.

7

“Transport Business” means the business of truck transportation of crude oil, fuels and other petroleum products, including without limitation, asphalt.

“Transport Material Contract” means any Contract material to Transport or to the ownership and operations of the Transport Business or the ownership, use or operation of the Transport Assets.

“Trigger Event” means any transaction or series of transactions (regardless of the structure or form of such transaction or series of transactions) by WRS or any of its Affiliates with a third party that directly or indirectly involves the sale, transfer or monetization by WRS or any of its Affiliates with respect to all or a substantial portion of the Membership Interests, the Wholesale Business or the Transport Business, including the entering into any contract, agreement or arrangement in respect of any of the foregoing; provided, however, that a Trigger Event will not be deemed to have occurred if the value attributable to the Membership Interests, the Wholesale Business or the Transport Business, or any portion thereof, is not a material portion of the consideration received by WRS or its Affiliates in connection with any transaction that would otherwise be deemed a Trigger Event. For avoidance of doubt, a Trigger Event shall not include the inclusion of Membership Interests, the Wholesale Business, the Transport Business or any portion thereof, as part of internal reorganizations or spin-off transaction in accordance with Code Section 355 or similar transactions. As used herein, “substantial portion” means eighty percent (80%) or more. 

“Wholesale” has the meaning set forth in the recitals.

“Wholesale Assets” has the meaning set forth in Section 5.9.

“Wholesale Business” means the business of distribution of petroleum products to distributors, retailers and end users.

“Wholesale Material Contract” means any Contract material to Wholesale or to the ownership and operations of the Wholesale Business or the ownership, use or operation of the Wholesale Assets.

“Wholesale Membership Interests” has the meaning set forth in the recitals.

“WRS” has the meaning set forth in the preamble.

“WRS Indemnitee” has the meaning set forth in Section 4.1.

8

Exhibit 1

(a)    If any third party institutes any legal proceedings or asserts any claim or demand in respect of which indemnification is available under Section 4.1 or Section 4.2 of this Agreement, as applicable (a “Third Party Claim”), the Indemnified Party shall promptly give written notice of the assertion of the Third Party Claim to the Indemnifying Party; provided, however, that failure of the Indemnified Party to so notify the Indemnifying Party shall not release, waive or otherwise affect the Indemnifying Party’s obligations with respect to such claim, except to the extent the Indemnifying Party is prejudiced by such failure.

(b)    Subject to the provisions of this Exhibit 1, the Indemnifying Party shall have the right, at its sole expense, to be represented by counsel of its choice, which must be reasonably satisfactory to the Indemnified Party, and to defend against, negotiate, settle or otherwise deal with any Third Party Claim which relates to any Losses with respect to which it is subject to an indemnification obligation under this Agreement; provided that, in order to defend against, negotiate, settle or otherwise deal with any such Third Party Claim, the Indemnifying Party must first acknowledge in writing to the Indemnified Party its unqualified obligation to indemnify the Indemnified Party under this Agreement and provide to the Indemnified Party reasonable evidence that the Indemnifying Party has reasonably sufficient financial resources to enable it to fulfill its obligations under Article IV and this Exhibit 1. Notwithstanding the immediately preceding sentence, the Indemnifying Party shall not have the right to defend against, negotiate, settle or otherwise deal with any Third Party Claim:

(i)    if the Indemnified Party reasonably and in good faith believes that the Third Party Claim would reasonably be likely to be materially detrimental to the reputation, customer or supplier relations or future business prospects of the Indemnified Party or any of its Affiliates;

(ii)    unless the Third Party Claim is solely for monetary damages (except where any non-monetary relief being sought is merely incidental to a primary claim for monetary damages on the part of the Indemnified Party);

(iii)    if the Third Party Claim involves criminal allegations; or

(iv)    if the Indemnifying Party fails to prosecute or defend, actively and diligently, the Third Party Claim.

(c)    If the Indemnifying Party elects to defend against, negotiate, settle or otherwise deal with any Third Party Claim, it shall within five (5) days of the Indemnified Party’s written notice of the assertion of such Third Party Claim (or sooner if the nature of the Third Party Claim so requires) notify the Indemnified Party of its intent to do so; provided that the Indemnifying Party must conduct its defense of the Third Party Claim actively and diligently thereafter in order to preserve its rights in this regard. If the Indemnifying Party elects not to defend against, negotiate, settle or otherwise deal with any Third Party Claim; fails to notify the Indemnified Party of its election timely as provided in this Agreement; or contests its obligation to indemnify the Indemnified

1

Party for Losses relating to such Third Party Claim under this Agreement, then the Indemnified Party may defend against, negotiate, settle or otherwise deal with such Third Party Claim. If the Indemnified Party defends any Third Party Claim, then the Indemnifying Party shall reimburse the Indemnified Party for the expenses of defending such Third Party Claim upon submission of periodic bills. If the Indemnifying Party assumes the defense of any Third Party Claim, the Indemnified Party may participate, at his or its own expense, in the defense of such Third Party Claim; provided, however, that such Indemnified Party shall be entitled to participate in any such defense with separate counsel at the expense of the Indemnifying Party if (i) so requested by the Indemnifying Party to participate or (ii) in the reasonable opinion of counsel to the Indemnified Party a conflict or potential conflict exists between the Indemnified Party and the Indemnifying Party that would make such separate representation advisable. Each party shall provide reasonable access to each other party to such documents and information as may reasonably be requested in connection with the defense, negotiation or settlement of any Third Party Claim; provided, however, that nothing in this Agreement shall require any party to disclose any documents, materials or other information that is subject to attorney-client privilege. Notwithstanding anything in this Exhibit 1 to the contrary, the Indemnifying Party shall not enter into any settlement of any Third Party Claim without the written consent of the Indemnified Party if such settlement (i) would create any liability of the Indemnified Party for which the Indemnified Party is not entitled to indemnification under this Agreement, (ii) would provide for any injunctive relief or other non-monetary obligation affecting the Indemnified Party, or (iii) does not include an unconditional release of the Indemnified Party from all liability and obligation in respect of the Third Party Claim.

(d)    After any final decision, judgment or award is rendered by a Governmental Authority of competent jurisdiction and the expiration of the time in which to appeal therefrom, or a settlement is consummated, or the Indemnified Party and the Indemnifying Party have arrived at a mutually binding agreement, in each case with respect to a Third Party Claim, the Indemnified Party shall forward to the Indemnifying Party notice of any sums due and owing by the Indemnifying Party pursuant to this Agreement with respect to such matter, and the Indemnifying Party shall pay all of such remaining sums so due and owing to the Indemnified Party by wire transfer of immediately available funds within five (5) business days after the date of such notice.

2

Exhibit 2

ASSIGNMENT AND ASSUMPTION AGREEMENT

This Assignment and Assumption Agreement (this “Agreement”) is entered into as of July 31, 2020, by and between Western Refining Southwest, Inc., an Arizona corporation (“WRS”), and MPLX, a Delaware limited partnership (“MPLX”), pursuant to that certain Redemption Agreement, dated July 31, 2020, to which WRS and MPLX are parties (the “Redemption Agreement”). Capitalized terms used and not defined herein have the meanings given to such terms in the Redemption Agreement.

In accordance with Section 2.1 of the Redemption Agreement, for good and valuable consideration, the receipt and sufficiency of which is acknowledged, MPLX hereby assigns, transfers, conveys and delivers the Wholesale Membership Interests to WRS, free and clear of all Liens other than as set forth in the Organizational Documents of Wholesale and other than restrictions on transfer under applicable federal and state securities laws, and WRS hereby unconditionally and absolutely acquires, accepts and assumes from MPLX the Wholesale Membership Interests.

Notwithstanding anything herein to the contrary, nothing herein shall in any way vary the covenants, agreements, representations and warranties of any of the Parties set forth in the Redemption Agreement. If there is a conflict between the provisions of the Redemption Agreement and the provisions of this Agreement, the provisions of the Redemption Agreement shall control.

This Agreement shall be binding upon, inure to the benefit of, and be enforceable by MPLX, WRS and their respective successors and assigns. This Agreement may not be amended except by an instrument in writing authorized and signed by MPLX and WRS.

In Witness Whereof, the parties hereto have executed this Agreement as of the date set forth above.

MPLX LP By: MPLX GP LLC, its General Partner		WESTERN REFINING SOUTHWEST, INC.
By:		By:
Name:	Pamela K.M. Beall	Name:	Donald C. Templin
Title:	Executive Vice President and Chief Financial Officer	Title:	Vice President

1

EX-31.1

Exhibit 31.1

CERTIFICATION PURSUANT TO SECTION 302 OF

THE SARBANES-OXLEY ACT OF 2002

I, Michael J. Hennigan, certify that:

1. I have reviewed this report on Form 10-Q of MPLX LP;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: August 3, 2020	/s/ Michael J. Hennigan
	Michael J. Hennigan
	Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC (the general partner of MPLX LP)

EX-31.2

Exhibit 31.2

CERTIFICATION PURSUANT TO SECTION 302 OF

THE SARBANES-OXLEY ACT OF 2002

I, Pamela K.M. Beall, certify that:

1. I have reviewed this report on Form 10-Q of MPLX LP;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: August 3, 2020	/s/ Pamela K.M. Beall
	Pamela K.M. Beall
	Director, Executive Vice President and Chief Financial Officer of MPLX GP LLC (the general partner of MPLX LP)

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of MPLX LP (the “Partnership”) on Form 10-Q for the quarterly period ended June 30, 2020 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael J. Hennigan, Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC, the general partner of the Partnership, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Partnership.

Date: August 3, 2020

/s/ Michael J. Hennigan

Michael J. Hennigan

Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC (the general partner of MPLX LP)

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of MPLX LP (the “Partnership”) on Form 10-Q for the quarterly period ended June 30, 2020 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Pamela K.M. Beall, Director, Executive Vice President and Chief Financial Officer of MPLX GP LLC, the general partner of the Partnership, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Partnership.

Date: August 3, 2020

/s/ Pamela K.M. Beall

Pamela K.M. Beall

Director, Executive Vice President and Chief Financial Officer of MPLX GP LLC (the general partner of MPLX LP)

XML

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Jul. 30, 2020
Document Information [Line Items]
Document Transition Report	false
Document Quarterly Report	true
Title of 12(b) Security	Common Units Representing Limited Partnership Interests
Entity Incorporation, State or Country Code	DE
Document Type	10-Q
Document Period End Date	Jun. 30, 2020
Amendment Flag	false
Entity File Number	001-35714
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Trading Symbol	MPLX
Entity Registrant Name	MPLX LP
Entity Central Index Key	0001552000
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		1,058,750,442
Entity Address, Address Line One	200 E. Hardin Street,
Entity Address, City or Town	Findlay,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45840
City Area Code	419
Local Phone Number	421-2414
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Security Exchange Name	NYSE
Entity Tax Identification Number	27-0005456

XML

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Revenues and other income:
Total revenues from contracts with customers	$ 1,592		$ 1,717	[1]	$ 3,373		$ 3,425	[1]
Rental income	98		93	[2]	194		192	[2]
Rental income - related parties	237		286	[2]	471		611	[2]
Income/(loss) from equity method investments(2)	89		83	[2],[3]	(1,095)	[4],[5]	160	[2],[6]
Other income	2		4	[2]	3		4	[2]
Other income - related parties	63		27	[2]	127		53	[2]
Revenues	2,081		2,210	[1],[2]	3,073		4,445	[1],[2]
Costs and expenses:
Rental cost of sales	33		29	[2]	68		66	[2]
Rental cost of sales - related parties	41		36	[2]	87		79	[2]
Purchases - related parties	280		313	[2]	556		591	[2]
Depreciation and amortization	321	[7]	313	[2],[3],[7]	646		614	[2],[6]
Goodwill and Intangible Asset Impairment	0		0	[2],[3]	2,165		0	[2],[6]
General and administrative expenses	96		90	[2]	193		191	[2]
Other taxes	30		25	[2]	61		55	[2]
Costs and Expenses	1,203		1,325	[2]	4,681		2,648	[2]
Income/(loss) from operations	878		885	[2]	(1,608)		1,797	[2]
Related party interest and other financial costs	1		2	[2]	4		3	[2]
Interest expense (net of amounts capitalized of $10 million, $12 million, $23 million and $23 million, respectively)	206		214	[2]	417		428	[2]
Other financial costs	16		13	[2]	32		22	[2]
Income/(loss) before income taxes	655		656	[2]	(2,061)		1,344	[2]
(Benefit)/provision for income taxes	0		(1)	[2],[3]	0		(2)	[2]
Net income	655		657	[2],[3],[8]	(2,061)		1,346	[2],[6],[8]
Less: Net income (loss) attributable to noncontrolling interest	7		6	[2]	15		12	[2]
Income (Loss) Attributable to Predecessor	0		169	[2]	0		349	[2]
Net income (loss) attributable to MPLX LP	648	[9]	482	[2],[10]	(2,076)	[11]	985	[2],[12]
Limited partners' interest in net income (loss) attributable to MPLX LP	617		461	[2]	(2,138)		944	[2]
Weighted average limited partner units outstanding:
Equity Method Investment, Other than Temporary Impairment					1,264
Limited Partners Common Units
Costs and expenses:
Net income (loss) attributable to MPLX LP	$ 617	[9]	$ 440	[10]	$ (2,138)	[11]	$ 923	[12]
Net income (loss) attributable to MPLX LP per limited partner unit:
Common - basic (in USD per unit)	$ 0.58		$ 0.56	[2]	$ (2.02)		$ 1.16	[2]
Common - diluted (in USD per unit)	$ 0.58		$ 0.55	[2]	$ (2.02)		$ 1.16	[2]
Weighted average limited partner units outstanding:
Common - basic (in shares)	1,059		794	[2],[13]	1,059		794	[2],[14]
Common - diluted (in shares)	1,059		795	[2],[13]	1,059		795	[2],[14]
Service [Member]
Revenues and other income:
Total revenues from contracts with customers	$ 563		$ 619	[1],[2]	$ 1,175		$ 1,233	[1],[2]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	857		847	[1],[2]	1,785		1,650	[1],[2]
Service, Other [Member]
Revenues and other income:
Total revenues from contracts with customers	22		26	[1],[2]	61		60	[1],[2]
Product [Member]
Revenues and other income:
Total revenues from contracts with customers	120		189	[2]	289		405	[2]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	30		36	[1],[2]	63		77	[1],[2]
Oil and Gas, Refining and Marketing [Member]
Costs and expenses:
Cost of Goods and Services Sold	315		353	[2]	683		692	[2]
Natural Gas, Midstream [Member]
Costs and expenses:
Cost of Goods and Services Sold	87		166	[2]	222		360	[2]
Series A Preferred Stock [Member] | Preferred Partner [Member]
Costs and expenses:
Net income (loss) attributable to MPLX LP	21	[9]	21	[10]	41	[11]	41	[12]
Dividends, Preferred Stock	21		21	[2]	41		41	[2]
Series B Preferred Stock [Member] | Preferred Partner [Member]
Costs and expenses:
Net income (loss) attributable to MPLX LP	10	[9]	21	[10]	21	[11]	21	[12]
Dividends, Preferred Stock	$ 10		$ 0	[2]	$ 21		$ 0	[2]

[1] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[5] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

[6] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[7] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

[8] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[9] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[10] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[11] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[12] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[13] The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the three months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

[14] The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the six months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

XML

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Interest Costs Capitalized	$ 10	$ 12	$ 23	$ 23

XML

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	[1]	Jun. 30, 2020	Jun. 30, 2019	[1]
Statement of Comprehensive Income [Abstract]
Net (loss)/income	$ 655	$ 657	[2],[3]	$ (2,061)	$ 1,346	[2],[4]
Other comprehensive income/(loss), net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	0	0		(1)	1
Comprehensive income/(loss)	655	657		(2,062)	1,347
Less comprehensive income attributable to:
Noncontrolling interests	7	6		15	12
Comprehensive Income (loss), Net of Tax, Attributable to Predecessor	0	169		0	349
Comprehensive income/(loss) attributable to MPLX LP	$ 648	$ 482		$ (2,077)	$ 986

[1] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Assets
Cash and cash equivalents		$ 67	$ 15
Receivables, net		562	593
Current Assets, Related Parties		594	656
Inventories		115	110
Other current assets		48	110
Total current assets		1,386	1,484
Equity method investments		4,065	5,275
Property, plant and equipment, net		21,758	22,145
Intangibles, net		1,023	1,270
Goodwill		7,722	9,536
Operating Lease, Right-of-Use Asset		341	365
Other Assets, Related Parties, Noncurrent		676	303
Other noncurrent assets		51	52
Total assets		37,022	40,430
Current liabilities:
Accounts payable		145	242
Accrued Liabilities, Current		138	187
Current Liabilities, Related Parties		372	1,008
Accrued Property Plant and Equipment Current		154	283
Accrued interest payable		207	210
Operating Lease, Liability, Current		69	66
Other current liabilities		143	136
Total current liabilities		1,228	2,132
Long-term deferred revenue		261	217
Liabilities, Related Parties, Noncurrent		287	290
Long-term debt		20,556	19,704
Deferred income taxes		11	12
Operating Lease, Liability, Noncurrent		274	302
Deferred credits and other liabilities		175	192
Total liabilities		22,792	22,849
Commitments and contingencies (see Note 21)
Series A preferred units		968	968
Equity
Total MPLX LP partners’ capital		13,015	16,364
Accumulated other comprehensive loss	[1]	(16)	(15)
Noncontrolling interests		247	249
Total equity		13,262	16,613
Total liabilities, preferred units and equity		37,022	40,430
MPC
Assets
Other current assets		1	0
Operating Lease, Right-of-Use Asset		231	232
Current liabilities:
Operating Lease, Liability, Current		1	1
Operating Lease, Liability, Noncurrent		230	230
Series B Preferred Stock [Member]
Equity
Total MPLX LP partners’ capital		611	611
Limited Partners Common Units | Public
Equity
Total MPLX LP partners’ capital		9,469	10,800
Total equity		9,469	10,800
Limited Partners Common Units | MPC
Equity
Total MPLX LP partners’ capital		2,951	4,968
Total equity		2,951	4,968
LOOP and Explorer
Equity
Accumulated other comprehensive loss		(16)	(15)
Retained Earnings [Member] | MPC
Equity
Total equity		$ 0	$ 0

[1] These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”

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Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Jun. 30, 2020	Dec. 31, 2019
Limited Partners Common Units | Public
Units issued	393.0	392.0
Units Outstanding	393.0	392.0
Limited Partners Common Units | MPC
Units issued	666.0	666.0
Units Outstanding	666.0	666.0
Series B Preferred Stock [Member]
Units issued	0.6	0.6
Units Outstanding	0.6	0.6

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Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019	[1]
Operating activities:
Net (loss)/income	$ (2,061)		$ 1,346	[2],[3]
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Amortization of deferred financing costs	29		19
Depreciation and amortization	646		614	[3]
Goodwill and Intangible Asset Impairment	2,165		0	[3]
Deferred income taxes	(1)		(2)
Retirement Expenditures	0		1
Loss/(gain) on disposal of assets	1		(2)
Loss/(income) from equity method investments(2)	1,095	[4],[5]	(160)	[3]
Distributions from unconsolidated affiliates	226		245
Changes in:
Current receivables	31		75
Inventories	(7)		0
Fair value of derivatives	(9)		7
Current accounts payable and accrued liabilities	(102)		(117)
Current assets/current liabilities - related parties	27		(124)
Increase (Decrease) in Other Operating Assets and Liabilities, Net	(1)		1
Deferred revenue	49		46
All other, net	26		7
Net cash provided by operating activities	2,114		1,954
Investing activities:
Additions to property, plant and equipment	(708)		(1,136)
Proceeds from Contributions from Affiliates	0		6
Disposal of assets	43		8
Investments in unconsolidated affiliates	(222)		(323)
Distributions from unconsolidated affiliates - return of capital	110		2
Payments for (Proceeds from) Other Investing Activities	0		(4)
Net cash used in investing activities	(777)		(1,439)
Financing activities:
Long-term debt - borrowings	2,500		3,139
Long-term debt - repayments	(1,682)		(2,272)
Related party debt - borrowings	2,708		3,833
Related party debt - repayments	(3,302)		(3,789)
Distributions to noncontrolling interests	(17)		(12)
Distributions to unitholders and general partner	(1,445)		(1,038)
Proceeds from Contributions from Parent	20		28
Contributions from noncontrolling interests	0		94
All other, net	(5)		(9)
Net cash used in financing activities	(1,285)		(568)
Net increase/(decrease) in cash, cash equivalents and restricted cash	52		(53)
Cash, cash equivalents and restricted cash at beginning of period	15		85
Cash, cash equivalents and restricted cash at end of period	67		32
Equity Method Investment, Other than Temporary Impairment	1,264
Series A Preferred Stock [Member] | Preferred Partner [Member]
Financing activities:
Distributions to preferred unitholders	(41)		(40)
Series B Preferred Stock [Member] | Preferred Partner [Member]
Financing activities:
Distributions to preferred unitholders	(21)		0
Payments of Distributions on Preferred Units from Predecessor	$ 0		$ 502

[1] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[5] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

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Consolidated Statements of Equity - USD ($)		Total	Preferred Class B [Member]		Public Limited Partners Common Units	MPC Limited Partners Common Units		Accumulated Other Comprehensive Loss		Noncontrolling Interests	Equity of Predecessor MPC
Beginning Balance at Dec. 31, 2018		$ 17,731,000,000	$ 0		$ 8,336,000,000	$ (1,612,000,000)		$ (16,000,000)		$ 156,000,000	$ 10,867,000,000
Distributions to:	[1]	(669,000,000)	0		176,000,000	307,000,000		0		(6,000,000)	(180,000,000)
Contributions from:	[1]	15,000,000	0		0	0		0		0	15,000,000
Unitholders and general partner	[1]	(776,000,000)	0		(188,000,000)	(327,000,000)		0		0	(261,000,000)
Noncontrolling interests	[1]	(6,000,000)	0		0	0		0		(6,000,000)	0
Contributions from noncontrolling interests	[1]	(94,000,000)	0		0	0		0		(94,000,000)	0
Other	[1]	3,000,000	0		2,000,000	0		1,000,000		0	0
Ending Balance at Mar. 31, 2019	[1]	17,730,000,000	0		8,326,000,000	(1,632,000,000)		(15,000,000)		250,000,000	10,801,000,000
Beginning Balance at Dec. 31, 2018		17,731,000,000	0		8,336,000,000	(1,612,000,000)		(16,000,000)		156,000,000	10,867,000,000
Contributions from noncontrolling interests	[2]	(94,000,000)
Ending Balance at Jun. 30, 2019		17,611,000,000	0		8,305,000,000	(1,671,000,000)		(15,000,000)		250,000,000	10,742,000,000
Beginning Balance at Mar. 31, 2019	[1]	17,730,000,000	0		8,326,000,000	(1,632,000,000)		(15,000,000)		250,000,000	10,801,000,000
Distributions to:		(636,000,000)	0	[1]	168,000,000	293,000,000		0	[1]	(6,000,000)	(169,000,000)
Contributions from:		13,000,000	0	[1]	0	0	[1]	0	[1]	0	13,000,000
Unitholders and general partner		(764,000,000)	0	[1]	(191,000,000)	(332,000,000)		0	[1]	0	241,000,000
Noncontrolling interests		(6,000,000)	0	[1]	0	0		0		(6,000,000)	0	[1]
Other		2,000,000	0	[1]	2,000,000	0		0		0	0
Ending Balance at Jun. 30, 2019		17,611,000,000	0		8,305,000,000	(1,671,000,000)		(15,000,000)		250,000,000	10,742,000,000
Beginning Balance at Dec. 31, 2019		16,613,000,000	611,000,000		10,800,000,000	4,968,000,000		(15,000,000)		249,000,000	0
Distributions to:		2,736,000,000	(11,000,000)		(1,022,000,000)	(1,733,000,000)		0		(8,000,000)	0
Contributions from:		225,000,000	0		0	225,000,000		0		0	0
Unitholders and general partner		(738,000,000)	(21,000,000)		(271,000,000)	(446,000,000)		0		0	0
Noncontrolling interests		(9,000,000)	0		0	0		0		(9,000,000)	0
Other		1,000,000	0		2,000,000	0		(1,000,000)		0	0
Ending Balance at Mar. 31, 2020		13,356,000,000	601,000,000		9,509,000,000	3,014,000,000		(16,000,000)		248,000,000	0
Beginning Balance at Dec. 31, 2019		16,613,000,000	611,000,000		10,800,000,000	4,968,000,000		(15,000,000)		249,000,000	0
Unitholders and general partner			(21,000,000)
Contributions from noncontrolling interests		0
Ending Balance at Jun. 30, 2020		13,262,000,000	611,000,000		9,469,000,000	2,951,000,000		(16,000,000)		247,000,000	0
Beginning Balance at Mar. 31, 2020		13,356,000,000	601,000,000		9,509,000,000	3,014,000,000		(16,000,000)		248,000,000	0
Distributions to:		(634,000,000)	(10,000,000)		229,000,000	388,000,000		0		(7,000,000)	0
Contributions from:		6,000,000	0		0	6,000,000		0		0	0
Unitholders and general partner		(728,000,000)	0		(270,000,000)	(458,000,000)		0		0	0
Noncontrolling interests		(8,000,000)	0		0	0		0		(8,000,000)	0
Other		2,000,000	0		1,000,000	1,000,000		0		0	0
Ending Balance at Jun. 30, 2020		$ 13,262,000,000	$ 611,000,000		$ 9,469,000,000	$ 2,951,000,000		$ (16,000,000)		$ 247,000,000	$ 0

[1] Financial information for the first and second quarters of 2019 has been retrospectively adjusted for the acquisition of ANDX.

[2] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Description of the Business and Basis of Presentation

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Business Description and Basis of Presentation [Text Block]

Description of the Business and Basis of Presentation

Description of the Business – MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to “MPC” refer collectively to Marathon Petroleum Corporation as our sponsor and its subsidiaries, other than the Partnership. We are engaged in the transportation, storage and distribution of crude oil, asphalt and refined petroleum products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.

MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, asphalt and refined petroleum products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 9 for additional information regarding the operations and results of these segments.

On July 30, 2019, MPLX completed its acquisition by merger (the “Merger”) of Andeavor Logistics LP (“ANDX”). At the effective time of the Merger, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. See Note 3 for additional information regarding the Merger.

Impairments – The outbreak of COVID-19 and its development into a pandemic in March 2020 resulted in significant economic disruption globally. Actions taken by various governmental authorities, individuals and companies around the world to prevent the spread of COVID-19 through social distancing have restricted travel, many business operations, public gatherings and the overall level of individual movement and in-person interaction across the globe. Although there have been some signs of economic improvement, these events significantly reduced global economic activity and resulted in a decline in the demand for the midstream services we provide beginning with the first quarter of 2020. Macroeconomic conditions and global geopolitical events have also resulted in significant price volatility related to those aforementioned products.

The overall deterioration in the economy and the environment in which MPLX and its customers operate, as well as a sustained decrease in unit price, were considered triggering events resulting in impairments of the carrying value of certain assets during the first quarter of 2020. We recognized impairments related to goodwill, certain equity method investments and certain long-lived assets (including intangibles), within our G&P segment. Many of our producer customers refined and updated production forecasts in response to the current environment, which impacted their current and expected future demand for our services, including the future utilization of our assets. Additionally, certain of our contracts have commodity price exposure, including NGL prices, which have experienced increased volatility as noted above. The table below provides information related to the impairments recognized during the first quarter of 2020 as well as the corresponding footnote where additional information can be found. No additional events or circumstances arose during the second quarter of 2020 which would indicate the need for any additional impairment beyond those recognized during the first quarter.

(In millions)	Impairment		Footnote Reference
Goodwill	$	1,814	12
Equity method investments	1,264		4
Intangibles, net	177		12
Property, plant and equipment, net	174		11
Total impairments	$	3,429

Basis of Presentation – The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain amounts in prior years have been reclassified to conform to current year presentation.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Annual Report on Form 10-K for the year ended December 31, 2019. The results of

operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results to be expected for the full year.

In relation to the Merger described above and in Note 3, ANDX’s assets, liabilities and results of operations prior to the Merger are collectively included in what we refer to as the “Predecessor” from October 1, 2018, which was the date that MPC acquired Andeavor. MPLX’s acquisition of ANDX is considered a transfer between entities under common control due to MPC’s relationship with ANDX prior to the Merger. As an entity under common control with MPC, MPLX recorded the assets acquired and liabilities assumed on its consolidated balance sheets at MPC’s historical carrying value. Transfers of businesses between entities under common control require prior periods to be retrospectively adjusted for those dates that the entity was under common control. Accordingly, the accompanying financial statements and related notes of MPLX LP have been retrospectively adjusted to include the historical results of ANDX beginning October 1, 2018.

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule. Distributions, although earned, are not accrued until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 6.

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Accounting Standards Accounting Standards

6 Months Ended

Jun. 30, 2020

Accounting Changes and Error Corrections [Abstract]

Accounting Standards Update and Change in Accounting Principle [Text Block]

Recently Adopted

ASU 2016-13, Credit Losses - Measurement of Credit Losses on Financial Instruments

Effective January 1, 2020, we adopted ASU 2016-13 using the modified retrospective transition method. This ASU requires entities to consider a broader range of information to estimate expected credit losses, which may result in earlier recognition of losses. The ASU requires the company to utilize an expected loss methodology in place of the incurred loss methodology for financial instruments, including trade receivables, and off-balance sheet credit exposures. Adoption of the standard did not have a material impact on our financial statements.

We are exposed to credit losses, primarily as a result of the midstream services that we provide. We assess each customer’s ability to pay through our credit review process, which considers various factors such as external credit ratings; a review of financial statements to determine liquidity, leverage, trends and business specific risks; market information; pay history and our business strategy. We monitor our ongoing credit exposure through timely review of customer payment activity. At June 30, 2020, we reported $562 million of accounts receivable, net of allowances of $1 million.

We also adopted the following ASU’s during the first six months of 2020, which did not have a material impact to our financial statements or financial statement disclosures:

ASU		Effective Date
2018-13	Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement	January 1, 2020
2020-04	Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting	April 1, 2020

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Acquisitions

6 Months Ended

Jun. 30, 2020

Business Combinations [Abstract]

Acquisitions

Acquisitions

Acquisition of Andeavor Logistics LP

As previously disclosed, on May 7, 2019, ANDX, Tesoro Logistics GP, LLC (then the general partner of ANDX (“TLGP”)), MPLX, MPLX GP LLC (the general partner of MPLX (“MPLX GP”)), and MPLX MAX LLC, a wholly owned subsidiary of MPLX (“Merger Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) that provided for, among other things, the merger of Merger Sub with and into ANDX. On July 30, 2019, the Merger was completed, and ANDX survived the Merger as a wholly owned subsidiary of MPLX. At the effective time of the Merger, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. See Note 7 for information on units issued in connection with the Merger.

Additionally, as a result of the Merger, each ANDX TexNew Mex Unit issued and outstanding immediately prior to the effective time of the Merger was converted into a right for Western Refining Southwest, Inc. (“WRSW”), a wholly owned subsidiary of MPC, as the holder of all such units, to receive a unit representing a substantially equivalent limited partner interest in MPLX (the “MPLX TexNew Mex Units”). By virtue of the conversion, all ANDX TexNew Mex Units were cancelled and ceased to exist as of the effective time of the Merger. The MPLX TexNew Mex Units are a new class of units in MPLX substantially equivalent to the ANDX TexNew Mex Units, including substantially equivalent rights, powers, duties and obligations that the ANDX TexNew Mex Units had immediately prior to the closing of the Merger.

As a result of the Merger, the ANDX Special Limited Partner Interest outstanding immediately prior to the effective time of the Merger was converted into a right for Southwest Inc., as the holder of all such interest, to receive a substantially equivalent special limited partner interest in MPLX (the “MPLX Special Limited Partner Interest”). By virtue of the conversion, the ANDX Special Limited Partner Interest was cancelled and ceased to exist as of the effective time of the Merger. For information on ANDX’s preferred units, please see Note 7.

The assets of ANDX consist of a network of owned and operated crude oil, refined product and natural gas pipelines; crude oil and water gathering systems; refining logistics assets; terminals with crude oil and refined products storage capacity; rail facilities; marine terminals including storage; bulk petroleum distribution facilities; a trucking fleet; and natural gas processing and fractionation systems and complexes. The assets are located in the western and inland regions of the United States and complement MPLX’s existing business and assets.

MPC accounted for its October 1, 2018 acquisition of Andeavor (including acquiring control of ANDX), using the acquisition method of accounting, which required Andeavor assets and liabilities to be recorded by MPC at the acquisition date fair value. The Merger was closed on July 30, 2019, and the results of ANDX have been incorporated into the results of MPLX as of October 1, 2018, which is the date that common control was established. As a result of MPC’s relationship with both MPLX and ANDX, the Merger has been treated as a common control transaction, which requires the recasting of MPLX’s historical results and the recognition of assets acquired and liabilities assumed using MPC’s historical carrying value. We recognized $5 million in acquisition costs during the first half of 2019 related to the Merger, which are reflected in general and administrative expenses. For the three and six months ended June 30, 2019, we recognized $588 million and $1,177 million of revenues and other income, respectively, related to ANDX. For the three and six months ended June 30, 2019 we recognized $168 million and $348 million, respectively, of net income related to ANDX.

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Equity Method Investments

6 Months Ended

Jun. 30, 2020

Equity Method Investments and Joint Ventures [Abstract]

Investments and Noncontrolling Interests [Text Block]

Investments and Noncontrolling Interests

The following table presents MPLX’s equity method investments at the dates indicated:

	Ownership as of	Carrying value at
	June 30,	June 30,		December 31,
(In millions, except ownership percentages)	2020	2020		2019
L&S
MarEn Bakken Company LLC(1)	25%	$	477	$	481
Illinois Extension Pipeline Company, L.L.C.	35%	268		265
LOOP LLC	41%	242		238
Andeavor Logistics Rio Pipeline LLC(2)	67%	196		202
Minnesota Pipe Line Company, LLC	17%	190		190
Whistler Pipeline LLC(2)	38%	188		134
Explorer Pipeline Company	25%	79		83
W2W Holdings LLC(2)(3)	50%	77		—
Wink to Webster Pipeline LLC(2)(3)	15%	—		126
Other(2)		60		55
Total L&S		1,777		1,774
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	725		1,984
Sherwood Midstream LLC(2)	50%	560		537
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	308		302
Rendezvous Gas Services, L.L.C.(2)	78%	166		170
Sherwood Midstream Holdings LLC(2)	51%	152		157
Centrahoma Processing LLC	40%	151		153
Other(2)		226		198
Total G&P		2,288		3,501
Total		$	4,065	$	5,275

(1) The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.    

(2) Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

(3) During the six months ended June 30, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

For those entities that have been deemed to be VIEs, neither MPLX nor any of its subsidiaries have been deemed to be the primary beneficiary due to voting rights on significant matters. While we have the ability to exercise influence through participation in the management committees which make all significant decisions, we have equal influence over each committee as a joint interest partner and all significant decisions require the consent of the other investors without regard to economic interest and as such we have determined that these entities should not be consolidated and apply the equity method of accounting with respect to our investments in each entity.

Sherwood Midstream has been deemed the primary beneficiary of Sherwood Midstream Holdings due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. Therefore, MPLX also reports its portion of Sherwood Midstream Holdings’ net assets as a component of its investment in Sherwood Midstream. As of June 30, 2020, MPLX has a 24.47 percent indirect ownership interest in Sherwood Midstream Holdings through Sherwood Midstream.

MPLX’s maximum exposure to loss as a result of its involvement with equity method investments includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. MPLX did not provide any financial support to equity method investments that it was not contractually obligated to provide during the six months ended June 30, 2020.

During the first quarter of 2020, we recorded an other than temporary impairment for three joint ventures in which we have an interest as discussed in Note 1. Impairment of these investments was $1,264 million, of which $1,251 million was related to MarkWest Utica EMG, L.L.C. and its investment in Ohio Gathering Company, L.L.C. The fair value of the investments was determined based upon applying the discounted cash flow method, which is an income approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future cash flows, including prices and volumes, the weighted average cost of capital and the long-term growth rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As such, the fair value of these equity method investments represents a Level 3 measurement. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment test will prove to be an accurate prediction of the future. The impairment was recorded through “Income from equity method investments.” The impairments were largely due to a reduction in forecasted volumes gathered and processed by the systems operated by the joint ventures. There were no additional impairments recorded during the second quarter of 2020.

Summarized financial information for MPLX’s equity method investments for the six months ended June 30, 2020 and 2019 is as follows:

	Six Months Ended June 30, 2020
(In millions)	VIEs			Non-VIEs		Total
Revenues and other income	$	(43	)	$	640	$	597
Costs and expenses	202			274		476
Income from operations	(245		)	366		121
Net income	(283		)	332		49
(Loss)/income from equity method investments(1)	$	(1,178	)	$	83	$	(1,095	)

(1) Includes the impact of any basis differential amortization or accretion in addition to the impairment of $1,264 million.

	Six Months Ended June 30, 2019(1)
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	306	$	724	$	1,030
Costs and expenses	159		295		454
Income from operations	147		429		576
Net income	127		383		510
Income from equity method investments(2)	$	54	$	106	$	160

(1) Financial information for the first six months of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Includes the impact of any basis differential amortization or accretion.

Summarized balance sheet information for MPLX’s equity method investments as of June 30, 2020 and December 31, 2019 is as follows:

	June 30, 2020
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	357	$	317	$	674
Noncurrent assets	5,824		5,061		10,885
Current liabilities	265		181		446
Noncurrent liabilities	$	656	$	853	$	1,509

	December 31, 2019
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	534	$	330	$	864
Noncurrent assets	5,862		5,134		10,996
Current liabilities	192		245		437
Noncurrent liabilities	$	305	$	822	$	1,127

As of June 30, 2020, the underlying net assets of MPLX’s investees in the G&P segment exceeded the carrying value of its equity method investments by approximately $59 million. At December 31, 2019, the carrying value of MPLX’s equity method investments in the G&P segment exceeded the underlying net assets of its investees by approximately $1.0 billion. As of June 30, 2020 and December 31, 2019, the carrying value of MPLX’s equity method investments in the L&S segment exceeded the underlying net assets of its investees by $330 million and $329 million, respectively. At June 30, 2020 and December 31, 2019, the G&P basis difference was being amortized into net income over the remaining estimated useful lives of the underlying assets, except for $31 million and $498 million of excess related to goodwill, respectively. At June 30, 2020 and December 31, 2019, the L&S basis difference was being amortized into net income over the remaining estimated useful lives of the underlying assets, except for $167 million of excess related to goodwill.

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Related Party Agreements and Transactions

6 Months Ended

Jun. 30, 2020

Related Party Transactions [Abstract]

Related Party Agreements and Transactions

Related Party Agreements and Transactions

MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below.

MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum throughput volumes on crude oil and refined products and other fees for storage capacity; operating and management fees; as well as reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under the marine transportation service agreement. MPLX also has a keep-whole commodity agreement with MPC under which MPC pays us a processing fee for NGLs related to keep-whole agreements and delivers shrink gas to the producers on our behalf. We pay MPC a marketing fee in exchange for assuming the commodity risk. Additionally, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services-type agreements as well as other various agreements.

Related Party Loan

MPLX is party to a loan agreement with MPC Investment LLC (“MPC Investment”) (the “MPC Loan Agreement”). Under the terms of the agreement, MPC Investment makes a loan or loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC Investment. In connection with the Merger, on July 31, 2019, MPLX and MPC Investment amended and restated the MPC Loan Agreement to increase the borrowing capacity under the MPC Loan Agreement to $1.5 billion in aggregate principal amount of all loans outstanding at any one time. The entire unpaid principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), shall become due and payable on July 31, 2024, provided that MPC Investment may demand payment of all or any portion of the outstanding principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), at any time prior to July 31, 2024. Borrowings under the MPC Loan Agreement prior to July 31, 2019 bore interest at LIBOR plus 1.50 percent while borrowings as of and after July 31, 2019 bear interest at LIBOR plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 15. Activity on the MPC Loan Agreement was as follows:

(In millions)	Six Months Ended June 30, 2020			Year Ended December 31, 2019
Borrowings	$	2,708		$	8,540
Average interest rate of borrowings	2.733		%	3.441		%
Repayments	$	3,302		$	7,946
Outstanding balance at end of period(1)	$	—		$	594

(1) Included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

Prior to the Merger, ANDX was also party to a loan agreement with MPC (“ANDX-MPC Loan Agreement”). This facility was entered into on December 21, 2018, with a borrowing capacity of $500 million. In connection with the Merger, on July 31, 2019, MPLX repaid the entire outstanding balance and terminated the ANDX-MPC Loan Agreement. Activity on the ANDX-MPC Loan Agreement prior to the Merger was as follows:

(In millions)	Year Ended December 31, 2019
Borrowings	$	773
Average interest rate of borrowings	4.249		%
Repayments	$	773
Outstanding balance at end of period	$	—

Related Party Revenue

Related party sales to MPC consist of crude oil and refined products pipeline and trucking transportation services based on tariff/contracted rates; storage, terminal and fuels distribution services based on contracted rates; and marine transportation services. Related party sales to MPC also consist of revenue related to volume deficiency credits.

MPLX also has operating agreements with MPC under which it receives a fee for operating MPC’s retained pipeline assets and a fixed annual fee for providing oversight and management services required to run the marine business. MPLX also receives management fee revenue for engineering, construction and administrative services for operating certain of its equity method investments.

Revenue received from related parties included on the Consolidated Statements of Income was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Service revenues - related parties
MPC	$	857	$	847	$	1,784	$	1,650
Other	—		—		1		—
Total Service revenue - related parties	857		847		1,785		1,650
Rental income - related parties
MPC	237		286		471		611
Product sales - related parties(1)
MPC	30		36		63		77
Other income - related parties
MPC	48		10		96		20
Other	15		17		31		33
Total Other income - related parties	$	63	$	27	$	127	$	53

(1) There were additional product sales to MPC that net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and six months ended June 30, 2020, these sales totaled $52 million and $225 million. For the three and six months ended June 30, 2019, these sales totaled $295 million and $518 million.

Related Party Expenses

MPC provides executive management services and certain general and administrative services to MPLX under the terms of our omnibus agreements (“Omnibus charges”). Omnibus charges included in “Rental cost of sales - related parties” primarily relate to services that support MPLX’s rental operations and maintenance of assets available for rent. Omnibus charges included in “Purchases - related parties” primarily relate to services that support MPLX’s operations and maintenance activities, as well as compensation expenses. Omnibus charges included in “General and administrative expenses” primarily relate to services that support MPLX’s executive management, accounting and human resources activities. MPLX also obtains employee services from MPC under employee services agreements (“ESA charges”). ESA charges for personnel directly involved in or supporting operations and maintenance activities related to rental services are classified as “Rental cost of sales - related parties.” ESA charges for personnel directly involved in or supporting operations and maintenance activities related to other services are classified as “Purchases - related parties.” ESA charges for personnel involved in executive management, accounting and human resources activities are classified as “General and administrative expenses.” In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain lease agreements with MPC.

Expenses incurred from MPC under the omnibus and employee services agreements as well as other purchases from MPC included on the Consolidated Statements of Income are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Rental cost of sales - related parties
MPC	$	41	$	36	$	87	$	79
Purchases - related parties
MPC	276		308		547		581
Other	4		5		9		10
Total Purchase - related parties	280		313		556		591
General and administrative expenses
MPC	$	68	$	53	$	132	$	115

Some charges incurred under the omnibus and ESA agreements are related to engineering services and are associated with assets under construction. These charges are added to “Property, plant and equipment, net” on the Consolidated Balance Sheets. For the three and six months ended June 30, 2020, these charges totaled $15 million and $51 million, respectively. For the three and six months ended June 30, 2019, these charges totaled $38 million and $79 million, respectively.

Related Party Assets and Liabilities

Assets and liabilities with related parties appearing on the Consolidated Balance Sheets are detailed in the table below. This table identifies the various components of related party assets and liabilities, including those associated with leases (see Note 20 for additional information) and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts are recorded as “Current liabilities - related parties.” In many cases, MPC may then apply the amount of any such deficiency payments as a credit for volumes in excess of its minimum volume commitment in future periods under the terms of the applicable agreements. MPLX recognizes related party revenues for the deficiency payments when credits are used for volumes in excess of minimum quarterly volume commitments, where it is probable the customer will not use the credit in future periods or upon the expiration of the credits. The use or expiration of the credits is a decrease in “Current liabilities - related parties.” In addition, capital projects MPLX is undertaking at the request of MPC are reimbursed in cash and recognized in income over the remaining term of the applicable agreements or in some cases as an equity contribution from its sponsor.

(In millions)	June 30, 2020		December 31, 2019
Current assets - related parties
Receivables - MPC	$	547	$	621
Receivables - Other	7		22
Prepaid - MPC	11		9
Other - MPC	1		—
Lease Receivables - MPC	28		4
Total	594		656
Noncurrent assets - related parties
Long-term receivables - MPC	30		21
Right of use assets - MPC	231		232
Long-term lease receivables - MPC	395		43
Unguaranteed residual asset - MPC	20		7
Total	676		303
Current liabilities - related parties
Payables - MPC	260		911
Payables - Other	36		37
Operating lease liabilities - MPC	1		1
Deferred revenue - Minimum volume deficiencies - MPC	56		42
Deferred revenue - Project reimbursements - MPC	18		16
Deferred revenue - Project reimbursements - Other	1		1
Total	372		1,008
Long-term liabilities - related parties
Long-term operating lease liabilities - MPC	230		230
Long-term deferred revenue - Project reimbursements - MPC	51		53
Long-term deferred revenue - Project reimbursements - Other	6		7
Total	$	287	$	290

Other Related Party Transactions

From time to time, MPLX may also sell to or purchase from related parties, assets and inventory at the lesser of average unit cost or net realizable value. Sales to and purchases from related parties were not material for the six months ended June 30, 2020 and 2019.

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Net Income Per Limited Partner Unit

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Net Income Per Limited Partner Unit

Net Income/(Loss) Per Limited Partner Unit

Net income/(loss) per unit applicable to common units is computed by dividing net income/(loss) attributable to MPLX LP less income/(loss) allocated to participating securities by the weighted average number of common units outstanding. Additional MPLX common units, MPLX Series B preferred units, and TexNew Mex units were issued on July 30, 2019 as a result of the merger with ANDX as discussed in Note 3. Distributions declared on these newly issued common and Series B preferred units are a reduction to income available to MPLX common unit holders due to their participation in distributions of income.

Classes of participating securities for the three and six months ended June 30, 2020 and 2019 include:

	Six Months Ended June 30,
	2020	2019
Common Units	ü	ü
Equity-based compensation awards	ü	ü
Series A preferred units	ü	ü
Series B preferred units	ü	ü

For the three and six months ended June 30, 2020 and 2019, MPLX had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three and six months ended June 30, 2020 and 2019 were less than 1 million.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019			2020			2019
Net income/(loss) attributable to MPLX LP	$	648		$	482		$	(2,076	)	$	985
Less: Distributions declared on Series A preferred units(1)	21			21			41			41
Distributions declared on Series B preferred units(1)	10			21			21			21
Limited partners’ distributions declared on MPLX common units (including common units of general partner)(1)(2)	715			692			1,443			1,215
Undistributed net loss attributable to MPLX LP	$	(98	)	$	(252	)	$	(3,581	)	$	(292	)

(1) See Note 7 for distribution information.

(2) The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

	Three Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	715		$	21	$	10	$	746
Undistributed net loss attributable to MPLX LP	(98		)	—		—		(98		)
Net income attributable to MPLX LP(1)	$	617		$	21	$	10	$	648
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.58
Diluted	$	0.58

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Three Months Ended June 30, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	692		$	21	$	21	$	734
Undistributed net loss attributable to MPLX LP	(252		)	—		—		(252		)
Net income attributable to MPLX LP(1)	$	440		$	21	$	21	$	482
Weighted average units outstanding:
Basic(2)	794
Diluted(2)	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.56
Diluted	$	0.55

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

(2) The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the three months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

	Six Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,443		$	41	$	21	$	1,505
Undistributed net loss attributable to MPLX LP	(3,581		)	—		—		(3,581		)
Net (loss)/income attributable to MPLX LP(1)	$	(2,138	)	$	41	$	21	$	(2,076	)
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	(2.02	)
Diluted	$	(2.02	)

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Six Months Ended June 30, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,215		$	41	$	21	$	1,277
Undistributed net loss attributable to MPLX LP	(292		)	—		—		(292		)
Net income attributable to MPLX LP(1)	$	923		$	41	$	21	$	985
Weighted average units outstanding:
Basic(2)	794
Diluted(2)	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.16
Diluted	$	1.16

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

(2)

The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the six months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

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Equity

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Equity

Equity

The changes in the number of common units outstanding during the six months ended June 30, 2020 are summarized below:

(In units)	Common
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	253,291
Balance at June 30, 2020	1,058,608,762

Merger

In connection with the Merger and as discussed in Note 3, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units while ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. This resulted in the issuance of MPLX common units of approximately 102 million units to public unitholders and approximately 161 million units to MPC on July 30, 2019.

Series B Preferred Units

Prior to the Merger, ANDX had outstanding 600,000 units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of ANDX at a price to the public of $1,000 per unit. Upon completion of the Merger, the ANDX preferred units converted to preferred units of MPLX representing substantially equivalent limited partnership interests in MPLX (the “Series B preferred units”). The Series B preferred units are pari passu with the Series A preferred units with respect to distribution rights and rights upon liquidation. Distributions on the Series B preferred units are payable semi-annually in arrears on the 15th day, or the first business day thereafter, of February and August of each year up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent.

The changes in the Series B preferred unit balance from December 31, 2019 through June 30, 2020 are summarized below. Series B preferred units are included in the Consolidated Balance Sheets and Consolidated Statements of Equity within “Equity of Predecessor” for the period prior to the Merger and within “Series B preferred units” for the period following the Merger.

(In millions)	Series B Preferred Units
Balance at December 31, 2019	$	611
Net income allocated	21
Distributions received by Series B preferred unitholders	(21		)
Balance at June 30, 2020	$	611

TexNew Mex Units - Prior to the Merger, MPC held 80,000 Andeavor Logistics TexNew Mex units, representing all outstanding units. At the time of the Merger, each Andeavor Logistics TexNew Mex unit was automatically converted into TexNew Mex units of MPLX with substantially the same rights and obligations as the Andeavor Logistics TexNew Mex units. The TexNew Mex units represent the right to receive quarterly distribution payments in an amount calculated using the distributable cash flow generated by a particular portion of the TexNew Mex pipeline system, in excess of a base amount and adjusted for previously agreed upon stipulations and contingencies. In the fourth quarter of 2019, distributions of less than $1 million were earned by the TexNew Mex units, which were declared in January of 2020 and paid in February 2020. Distributions of $2 million were earned by the TexNew Mex units during the three months ended June 30, 2020.

Cash distributions – In accordance with the MPLX partnership agreement, on July 28, 2020, MPLX declared a quarterly cash distribution for the second quarter of 2020, totaling $715 million, or $0.6875 per common unit. This rate will also be received by Series A preferred unitholders. These distributions will be paid on August 14, 2020 to common unitholders of record on August 7, 2020. Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the Board of Directors. Accordingly, a cash distribution payment totaling $21 million will be paid to Series B unitholders on August 17, 2020.

Quarterly distributions for 2020 and 2019 are summarized below:

(Per common unit)	2020		2019
March 31,	$	0.6875	$	0.6575
June 30,	$	0.6875	$	0.6675

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and six months ended June 30, 2020 and 2019. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	715	$	692	$	1,443	$	1,215
Series A preferred unit distributions	21		21		41		41
Series B preferred unit distributions	10		21		21		21
Total cash distributions declared	$	746	$	734	$	1,505	$	1,277

The distribution on common units for the three and six months ended June 30, 2019 includes the impact of the issuance of approximately 102 million units issued to public unitholders and approximately 161 million units issued to MPC in connection with the Merger. Due to the timing of the closing, distributions presented in the table above include second quarter distributions on MPLX common units issued to former ANDX unitholders and Series B Unitholders in connection with the Merger. The distributions on common units exclude $12.5 million of waived distributions for the three and six months ended June 30, 2019.

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Series A Preferred Units

6 Months Ended

Jun. 30, 2020

Temporary Equity Disclosure [Abstract]

Redeemable Preferred Units

Series A Preferred Units

On May 13, 2016, MPLX LP issued approximately 30.8 million 6.5 percent Series A Convertible preferred units for a cash purchase price of $32.50 per unit. The Series A preferred units rank senior to all common units and pari passu with all Series B preferred units with respect to distributions and rights upon liquidation. The holders of the Series A preferred units are entitled to receive, when and if declared by the board, a quarterly distribution equal to the greater of $0.528125 per unit or the amount of distributions they would have received on an as converted basis. On July 28, 2020, MPLX declared a quarterly cash distribution of $0.6875 per common unit for the second quarter of 2020. Holders of the Series A preferred units will receive the common unit rate in lieu of the lower $0.528125 base amount.

The holders may convert their Series A preferred units into common units at any time, in full or in part, subject to minimum conversion amounts and conditions. After the fourth anniversary of the issuance date, MPLX may convert the Series A preferred units into common units at any time, in whole or in part, subject to certain minimum conversion amounts and conditions, if the closing price of MPLX LP common units is greater than $48.75 for the 20-day trading period immediately preceding the conversion notice date. The conversion rate for the Series A preferred units shall be the quotient of (a) the sum of (i) $32.50, plus (ii) any unpaid cash distributions on the applicable preferred unit, divided by (b) $32.50, subject to adjustment for unit distributions, unit splits and similar transactions. The holders of the Series A preferred units are entitled to vote on an as-converted basis with the common unitholders and have certain other class voting rights with respect to any amendment to the MPLX partnership agreement that would adversely affect any rights, preferences or privileges of the preferred units. In addition, upon certain events involving a change of control, the holders of preferred units may elect, among other potential elections, to convert their Series A preferred units to common units at the then change of control conversion rate.

Approximately 29.6 million Series A preferred units remaining outstanding as of June 30, 2020. The changes in the redeemable preferred balance from December 31, 2019 through June 30, 2020 are summarized below:

(In millions)	Redeemable Series A Preferred Units
Balance at December 31, 2019	$	968
Net income allocated	41
Distributions received by Series A preferred unitholders	(41		)
Balance at June 30, 2020	$	968

The Series A preferred units are considered redeemable securities under GAAP due to the existence of redemption provisions upon a deemed liquidation event which is outside MPLX’s control. Therefore, they are presented as temporary equity in the mezzanine section of the Consolidated Balance Sheets. The Series A preferred units have been recorded at their issuance date fair value, net of issuance costs. Income allocations increase the carrying value and declared distributions decrease the carrying value of the Series A preferred units. As the Series A preferred units are not currently redeemable and not probable of becoming redeemable, adjustment to the initial carrying amount is not necessary and would only be required if it becomes probable that the Series A preferred units would become redeemable.

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Segment Information

6 Months Ended

Jun. 30, 2020

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

Segment Information

MPLX’s chief operating decision maker is the chief executive officer (“CEO”) of its general partner. The CEO reviews MPLX’s discrete financial information, makes operating decisions, assesses financial performance and allocates resources on a type of service basis. MPLX has two reportable segments: L&S and G&P. Each of these segments is organized and managed based upon the nature of the products and services it offers.

• L&S – transports, stores, distributes and markets crude oil, asphalt, refined petroleum products and water. Also includes an inland marine business, terminals, rail facilities, storage caverns and refining logistics.

• G&P – gathers, processes and transports natural gas; and gathers, transports, fractionates, stores and markets NGLs.

Our CEO evaluates the performance of our segments using Segment Adjusted EBITDA. Amounts included in net income and excluded from Segment Adjusted EBITDA include: (i) depreciation and amortization; (ii) provision/(benefit) for income taxes; (iii) amortization of deferred financing costs; (iv) extinguishment of debt; (v) non-cash equity-based compensation; (vi) impairment expense; (vii) net interest and other financial costs; (viii) income/(loss) from equity method investments; (ix) distributions and adjustments related to equity method investments; (x) unrealized derivative gains/(losses); (xi) acquisition costs; (xii) noncontrolling interest; and (xiii) other adjustments as deemed necessary. These items are either: (i) believed to be

non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about revenues and other income, capital expenditures and investments in unconsolidated affiliates as well as total assets for our reportable segments:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019(1)		2020			2019(1)
L&S
Service revenue	$	931	$	922	$	1,935		$	1,811
Rental income	246		296		488			631
Product related revenue	21		20		40			35
Income from equity method investments	40		54		90			99
Other income	52		16		103			28
Total segment revenues and other income(2)	1,290		1,308		2,656			2,604
Segment Adjusted EBITDA(3)	839		570		1,711			1,129
Capital expenditures	108		230		292			428
Investments in unconsolidated affiliates	74		61		128			68
G&P
Service revenue	489		544		1,025			1,072
Rental income	89		83		177			172
Product related revenue	151		231		373			507
Income/(loss) from equity method investments	49		29		(1,185		)	61
Other income	13		15		27			29
Total segment revenues and other (loss)/income(2)	791		902		417			1,841
Segment Adjusted EBITDA(3)	388		350		810			721
Capital expenditures	110		326		244			632
Investments in unconsolidated affiliates	$	57	$	127	$	94		$	255

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

(3) See below for the reconciliation from Segment Adjusted EBITDA to net income.

(In millions)	June 30, 2020		December 31, 2019
Segment assets
Cash and cash equivalents	$	67	$	15
L&S	21,308		20,810
G&P	15,647		19,605
Total assets	$	37,022	$	40,430

The table below provides a reconciliation between net (loss)/income and Segment Adjusted EBITDA.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019(1)			2020			2019(1)
Reconciliation to Net (loss)/income:
L&S Segment Adjusted EBITDA	$	839		$	570		$	1,711		$	1,129
G&P Segment Adjusted EBITDA	388			350			810			721
Total reportable segments	1,227			920			2,521			1,850
Depreciation and amortization(2)	(321		)	(313		)	(646		)	(614		)
Benefit for income taxes	—			1			—			2
Amortization of deferred financing costs	(15		)	(12		)	(29		)	(19		)
Non-cash equity-based compensation	(3		)	(5		)	(8		)	(12		)
Impairment expense	—			—			(2,165		)	—
Net interest and other financial costs	(208		)	(217		)	(424		)	(434		)
Income/(loss) from equity method investments	89			83			(1,095		)	160
Distributions/adjustments related to equity method investments	(115		)	(132		)	(239		)	(254		)
Unrealized derivative (losses)/gains(3)	(6		)	—			9			(4		)
Acquisition costs	—			(4		)	—			(5		)
Other	(1		)	—			(2		)	—
Adjusted EBITDA attributable to noncontrolling interests	8			7			17			14
Adjusted EBITDA attributable to Predecessor(4)	—			329			—			662
Net (loss)/income	$	655		$	657		$	(2,061	)	$	1,346

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Depreciation and amortization attributable to L&S was $138 million and $276 million for the three and six months ended June 30, 2020, respectively, and $134 million and $260 million for the three and six months ended June 30, 2019, respectively. Depreciation and amortization attributable to G&P was $183 million and $370 million for the three and six months ended June 30, 2020, respectively, and $179 million and $354 million for the three and six months ended June 30, 2019, respectively.

(3) MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

(4)

The adjusted EBITDA adjustments related to Predecessor are excluded from adjusted EBITDA attributable to MPLX LP prior to the Merger.

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Inventories

6 Months Ended

Jun. 30, 2020

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consist of the following:

(In millions)	June 30, 2020		December 31, 2019
NGLs	$	2	$	5
Line fill	8		10
Spare parts, materials and supplies	105		95
Total inventories	$	115	$	110

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Property, Plant and Equipment

6 Months Ended

Jun. 30, 2020

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

Property, plant and equipment with associated accumulated depreciation is shown below:

(In millions)	Estimated Useful Lives	June 30, 2020		December 31, 2019
L&S
Pipelines	2-51 years	$	5,719	$	5,572
Refining Logistics	13-40 years	2,324		2,870
Terminals	4-40 years	1,281		1,109
Marine	15-20 years	960		906
Land, building and other	1-61 years	1,834		1,817
Construction-in progress		520		660
Total L&S property, plant and equipment		12,638		12,934
G&P
Gathering and transportation	5-40 years	7,374		7,159
Processing and fractionation	15-40 years	5,923		5,545
Land, building and other	3-40 years	489		484
Construction-in-progress		368		745
Total G&P property, plant and equipment		14,154		13,933
Total property, plant and equipment		26,792		26,867
Less accumulated depreciation(1)		5,034		4,722
Property, plant and equipment, net		$	21,758	$	22,145

(1) The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020 as discussed below.

Long-lived assets used in operations are assessed for impairment whenever changes in facts and circumstances indicate that the carrying value of the assets may not be recoverable based on the expected undiscounted future cash flow of an asset group. For purposes of impairment evaluation, long-lived assets must be grouped at the lowest level for which independent cash flows can be identified, which is at least at the segment level and in some cases for similar assets in the same geographic region where cash flows can be separately identified. If the sum of the undiscounted cash flows is less than the carrying value of an asset group, fair value is calculated, and the carrying value is written down if greater than the calculated fair value.

No impairment triggers were identified in the second quarter of 2020; however, during the first quarter of 2020, we did identify an impairment trigger relating to asset groups within our Western G&P reporting unit as a result of significant impacts to forecasted cash flows for these asset groups resulting from the first quarter events and circumstances as discussed in Note 1. The cash flows associated with these assets were significantly impacted by volume declines reflecting decreased forecasted producer customer production as a result of lower commodity prices. After assessing each asset group within the Western G&P reporting unit for impairment, only the East Texas G&P asset group resulted in the fair value of the underlying assets being less than the carrying value. As a result, an impairment of $174 million was recorded to “Impairment expense” on the Consolidated Statements of Income in the first quarter of 2020. Fair value of the assets was determined using a combination of an income and cost approach. The income approach utilized significant assumptions including management’s best estimates of the expected future cash flows, the estimated useful life of the asset group and discount rate. The cost approach utilized assumptions for the current replacement costs of similar assets adjusted for estimated depreciation and deterioration of the existing equipment and economic obsolescence. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of our impairment analysis will prove to be an accurate prediction of the future. The fair value measurements for the asset group fair values represent Level 3 measurements.

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Goodwill and Intangibles (Notes)

6 Months Ended

Jun. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets Disclosure [Text Block]

Goodwill and Intangibles

Goodwill

MPLX annually evaluates goodwill for impairment as of November 30, as well as whenever events or changes in circumstances indicate it is more likely than not that the fair value of a reporting unit with goodwill is less than its carrying amount.

There were no events or changes in circumstances noted in the second quarter of 2020 which would indicate it is more likely than not that the fair value of our reporting units with goodwill is less than their carrying amount. During the first quarter of 2020, we determined that an interim impairment analysis of the goodwill recorded was necessary based on consideration of a number of first quarter events and circumstances as discussed in Note 1. Our producer customers in our Eastern G&P region reduced production forecasts and drilling activity in response to the global economic downturn. Additionally, a decline in NGL prices impacted our future revenue forecast. After performing our evaluations related to the interim impairment of goodwill during the first quarter of 2020, we recorded an impairment of $1,814 million within the Eastern G&P reporting unit, which was recorded to “Impairment expense” on the Consolidated Statements of Income. The impairment was primarily driven by additional guidance related to the slowing of drilling activity, which has reduced production growth forecasts from our producer customers. This resulted in goodwill totaling approximately $7.7 billion as of March 31, 2020 within four reporting units. The fair value of the remaining reporting units with goodwill were in excess of their carrying value by percentages ranging from 8.5 percent to 270.0 percent. The reporting unit whose fair value exceeded its carrying amount by 8.5 percent, our Crude Gathering reporting unit, had goodwill totaling $1.1 billion at March 31, 2020. The operations which make up this reporting unit were acquired through the merger with ANDX. MPC accounted for its October 1, 2018 acquisition of Andeavor (including acquiring control of ANDX), using the acquisition method of accounting, which required Andeavor assets and liabilities to be recorded by MPC at the acquisition date fair value. The Merger was closed on July 30, 2019 and has been treated as a common control transaction, which required the recognition of assets acquired and liabilities assumed using MPC’s historical carrying value. As such, given the short amount of time from when fair value was established to the date of the impairment test, the amount by which the fair value exceeded the carrying value within this reporting unit was not unexpected.

Our reporting units are one level below our operating segments and are determined based on the way in which segment management operates and reviews each operating segment. The fair value of our six reporting units was determined based on applying both a discounted cash flow or income approach as well as a market approach. The discounted cash flow fair value estimate is based on known or knowable information at the measurement date. The significant assumptions that were used to develop the estimates of the fair values under the discounted cash flow method included management’s best estimates of the expected future results and discount rate, which ranged from 9.5 percent to 11.5 percent. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the interim goodwill impairment test will prove to be an accurate prediction of the future. The fair value measurements for the individual reporting units represent Level 3 measurements.

After performing our evaluations related to the impairment of goodwill during the fiscal year ending December 31, 2019, we recorded an impairment of $1,197 million within the Western G&P reporting unit. The remainder of the reporting units’ fair values were in excess of their carrying values. The impairment was primarily driven by updated guidance related to the slowing of drilling activity, which has reduced production growth forecasts from our producer customers. This resulted in goodwill totaling approximately $9.5 billion as of December 31, 2019, with all but one of our six reporting units having goodwill.

The changes in carrying amount of goodwill were as follows:

(In millions)	L&S		G&P			Total
Gross goodwill as of December 31, 2018	$	7,234	$	2,912		$	10,146
Accumulated impairment losses	—		(130		)	(130		)
Balance as of December 31, 2018	7,234		2,782			10,016
Impairment losses	—		(1,197		)	(1,197		)
Acquisitions	488		229			717
Balance as of December 31, 2019	7,722		1,814			9,536
Impairment losses	—		(1,814		)	(1,814		)
Balance as of June 30, 2020	7,722		—			7,722
Gross goodwill as of June 30, 2020	7,722		3,141			10,863
Accumulated impairment losses	—		(3,141		)	(3,141		)
Balance as of June 30, 2020	$	7,722	$	—		$	7,722

Intangible Assets

During the first quarter of 2020, we also determined that an impairment analysis of intangibles within our Western G&P reporting unit was necessary. See Note 11 for additional information regarding our assessment around the Western G&P reporting unit, and more specifically our East Texas G&P asset group. The fair value of the intangibles in our East Texas G&P asset group was determined based on applying the multi-period excess earnings method, which is an income approach. Key assumptions included management’s best estimates of the expected future cash flows from existing customers, customer attrition rates and the discount rate. After performing our evaluations related to the impairment of intangible assets associated with our East Texas G&P asset group during the first quarter of 2020, we recorded an impairment of $177 million to “Impairment expense” on the Consolidated Statements of Income related to our customer relationships.

MPLX’s remaining intangible assets are comprised of customer contracts and relationships. Gross intangible assets with accumulated amortization as of June 30, 2020 and December 31, 2019 is shown below:

		June 30, 2020							December 31, 2019
(In millions)	Useful Life	Gross		Accumulated Amortization(1)(2)			Net		Gross		Accumulated Amortization			Net
L&S	6 - 8 years	$	283	$	(63	)	$	220	$	283	$	(45	)	$	238
G&P	6 - 25 years	1,288		(485		)	803		1,288		(256		)	1,032
		$	1,571	$	(548	)	$	1,023	$	1,571	$	(301	)	$	1,270

(1) Amortization expense attributable to the G&P and L&S segments for the six months ended June 30, 2020 was $52 million and $18 million, respectively.

(2) Impairment charge of $177 million is included within the G&P accumulated amortization.

Estimated future amortization expense related to the intangible assets at June 30, 2020 is as follows:

(In millions)
2020	$	64
2021	128
2022	128
2023	128
2024	124
Thereafter	451
Total	$	1,023

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Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

Fair Values – Recurring

Fair value measurements and disclosures relate primarily to MPLX’s derivative positions as discussed in Note 14. The following table presents the financial instruments carried at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 by fair value hierarchy level. MPLX has elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty.

	June 30, 2020					December 31, 2019
(In millions)	Assets		Liabilities			Assets		Liabilities
Significant unobservable inputs (Level 3)
Embedded derivatives in commodity contracts	$	—	$	(51	)	$	—	$	(60	)
Total carrying value on Consolidated Balance Sheets	$	—	$	(51	)	$	—	$	(60	)

Level 3 instruments include all NGL transactions and embedded derivatives in commodity contracts. The embedded derivative liability relates to a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.38 to $0.92 per gallon with a weighted average of $0.53 per gallon per the current term of the embedded derivative and (2) the probability of renewal of 100 percent for the first five-year term and

second five-year term of the gas purchase commitment and related keep-whole processing agreement, respectively. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of June 30, 2020 or December 31, 2019.

Changes in Level 3 Fair Value Measurements

The following table is a reconciliation of the net beginning and ending balances recorded for net assets and liabilities classified as Level 3 in the fair value hierarchy.

	Three Months Ended June 30, 2020					Three Months Ended June 30, 2019
(In millions)	Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)			Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	—	$	(45	)	$	—	$	(65	)
Total (losses)/gains (realized and unrealized) included in earnings(1)	—		(7		)	—		(1		)
Settlements	—		1			—		1
Fair value at end of period	—		(51		)	—		(65		)
The amount of total (losses)/gains for the period included in earnings attributable to the change in unrealized gains/(losses) relating to liabilities still held at end of period	$	—	$	(6	)	$	—	$	(2	)

	Six Months Ended June 30, 2020					Six Months Ended June 30, 2019
(In millions)	Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)			Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	—	$	(60	)	$	—	$	(61	)
Total gains/(losses) (realized and unrealized) included in earnings(1)	—		7			—		(7		)
Settlements	—		2			—		3
Fair value at end of period	—		(51		)	—		(65		)
The amount of total gains/(losses) for the period included in earnings attributable to the change in unrealized gains/(losses) relating to liabilities still held at end of period	$	—	$	7		$	—	$	(5	)

(1) Gains and losses on commodity derivative contracts classified as Level 3 are recorded in “Product sales” on the Consolidated Statements of Income. Gains and losses on derivatives embedded in commodity contracts are recorded in “Purchased product costs” and “Cost of revenues” on the Consolidated Statements of Income.

Fair Values – Reported

MPLX’s primary financial instruments are cash and cash equivalents, receivables, receivables from related parties, lease receivables from related parties, accounts payable, payables to related parties and long-term debt. MPLX’s fair value assessment incorporates a variety of considerations, including (1) the duration of the instruments, (2) MPC’s investment-grade credit rating and (3) the historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. MPLX believes the carrying values of its current assets and liabilities approximate fair value. The recorded value of the amounts outstanding under the bank revolving credit facility, if any, approximates fair value due to the variable interest rate that approximates current market rates. Derivative instruments are recorded at fair value, based on available market information (see Note 14).

The fair value of MPLX’s long-term debt is estimated based on recent market non-binding indicative quotes. The fair value of the SMR liability is estimated using a discounted cash flow approach based on the contractual cash flows and MPLX’s unsecured borrowing rate. The long-term debt and SMR liability fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of the long-term debt, excluding finance leases, and SMR liability:

	June 30, 2020				December 31, 2019
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-term debt	$	21,919	$	20,646	$	21,054	$	19,800
SMR liability	$	88	$	78	$	90	$	80

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Derivative Financial Instruments

6 Months Ended

Jun. 30, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities Disclosure [Text Block]

Derivative Financial Instruments

As of June 30, 2020, MPLX had no outstanding commodity contracts beyond the embedded derivative discussed below.

Embedded Derivative - MPLX has a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2022. The customer has the unilateral option to extend the agreement for two consecutive five-year terms through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending options have been aggregated into a single compound embedded derivative. The probability of the customer exercising its options is determined based on assumptions about the customer’s potential business strategy decision points that may exist at the time they would elect whether to renew the contract. The changes in fair value of this compound embedded derivative are based on the difference between the contractual and index pricing and the probability of the producer customer exercising its option to extend. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. As of June 30, 2020 and December 31, 2019, the estimated fair value of this contract was a liability of $51 million and $60 million, respectively.

Certain derivative positions are subject to master netting agreements, therefore, MPLX has elected to offset derivative assets and liabilities that are legally permissible to be offset. As of June 30, 2020 and December 31, 2019, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	June 30, 2020					December 31, 2019
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability			Asset		Liability
Commodity contracts(1)
Other current assets / Other current liabilities	$	—	$	(3	)	$	—	$	(5	)
Other noncurrent assets / Deferred credits and other liabilities	—		(48		)	—		(55		)
Total	$	—	$	(51	)	$	—	$	(60	)

(1) Includes embedded derivatives in commodity contracts as discussed above.

For further information regarding the fair value measurement of derivative instruments, including the effect of master netting arrangements or collateral, see Note 13. There were no material changes to MPLX’s policy regarding the accounting for Level 2 and Level 3 instruments as previously disclosed in MPLX’s Annual Report on Form 10-K for the year ended December 31, 2019. MPLX does not designate any of its commodity derivative positions as hedges for accounting purposes.

The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019			2020			2019
Purchased product costs
Realized (loss)/gain	$	(1	)	$	(1	)	$	(2	)	$	(3	)
Unrealized (loss)/gain	(6		)	—			9			(4		)
Purchased product costs derivative (loss)/gain	(7		)	(1		)	7			(7		)
Total derivative (loss)/gain	$	(7	)	$	(1	)	$	7		$	(7	)

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Debt

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Debt

Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	June 30, 2020			December 31, 2019
MPLX LP:
Bank revolving credit facility	$	825		$	—
Term loan facility	1,000			1,000
Floating rate senior notes	2,000			2,000
Fixed rate senior notes	16,887			16,887
Consolidated subsidiaries:
MarkWest	23			23
ANDX	190			190
Financing lease obligations(1)	13			19
Total	20,938			20,119
Unamortized debt issuance costs	(100		)	(106		)
Unamortized discount/premium	(279		)	(300		)
Amounts due within one year	(3		)	(9		)
Total long-term debt due after one year	$	20,556		$	19,704

(1)    See Note 20 for lease information.

Credit Agreement

Effective July 30, 2019, in connection with the closing of the Merger, MPLX amended and restated its existing revolving credit facility (the “MPLX Credit Agreement”) to, among other things, increase borrowing capacity to up to $3.5 billion and extend its term from July 2022 to July 2024. During the six months ended June 30, 2020, MPLX borrowed $2.5 billion under the MPLX Credit Agreement, at an average interest rate of 1.525 percent, and repaid $1.675 billion. At June 30, 2020, MPLX had $825 million in outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of $2.675 billion, or 76.4 percent of the borrowing capacity.

Term Loan Agreement

On September 26, 2019, MPLX entered into a Term Loan Agreement which provides for a committed term loan facility for up to an aggregate of $1 billion. Borrowings under the Term Loan Agreement bear interest, at MPLX’s election, at either (i) the Adjusted LIBO Rate (as defined in the Term Loan Agreement) plus a margin ranging from 75.0 basis points to 100.0 basis points per annum, depending on MPLX’s credit ratings, or (ii) the Alternate Base Rate (as defined in the Term Loan Agreement). Amounts borrowed under the Term Loan Agreement will be due and payable on September 26, 2021. As of June 30, 2020, MPLX had $1.0 billion outstanding on the term loan at an average interest rate of 1.665 percent.

Floating Rate Senior Notes

On September 9, 2019, MPLX issued $2.0 billion aggregate principal amount of floating rate senior notes in a public offering, consisting of $1.0 billion aggregate principal amount of notes due September 2021 and $1.0 billion aggregate principal amount of notes due September 2022 (collectively, the “Floating Rate Senior Notes”). The Floating Rate Senior Notes were offered at a price to the public of 100 percent of par. The Floating Rate Senior Notes are callable, in whole or in part, at par plus accrued and unpaid interest at any time on or after September 10, 2020. Interest on the Floating Rate Senior Notes is payable quarterly in March, June, September and December, commencing on December 9, 2019. The interest rate applicable to the floating rate senior notes due September 2021 is LIBOR plus 0.9 percent per annum. The interest rate applicable to the floating rate senior notes due September 2022 is LIBOR plus 1.1 percent per annum.

Fixed Rate Senior Notes

MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes expiring between 2022 and 2058 with interest rates ranging from 3.375 percent to 6.375 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.

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Revenue

6 Months Ended

Jun. 30, 2020

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer [Text Block]

Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three and six months ended June 30, 2020 and 2019:

	Three Months Ended June 30, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	77	$	486	$	563
Service revenue - related parties	854		3		857
Service revenue - product related	—		22		22
Product sales	17		103		120
Product sales - related parties	4		26		30
Total revenues from contracts with customers	$	952	$	640	1,592
Non-ASC 606 revenue(1)					489
Total revenues and other income					$	2,081

	Three Months Ended June 30, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	79	$	540	$	619
Service revenue - related parties	843		4		847
Service revenue - product related	—		26		26
Product sales	15		174		189
Product sales - related parties	5		31		36
Total revenues from contracts with customers	$	942	$	775	1,717
Non-ASC 606 revenue(1)					493
Total revenues and other income					$	2,210

	Six Months Ended June 30, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	161	$	1,014	$	1,175
Service revenue - related parties	1,774		11		1,785
Service revenue - product related	—		61		61
Product sales	32		257		289
Product sales - related parties	8		55		63
Total revenues from contracts with customers	$	1,975	$	1,398	3,373
Non-ASC 606 loss(1)					(300		)
Total revenues and other income					$	3,073

	Six Months Ended June 30, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	165	$	1,068	$	1,233
Service revenue - related parties	1,646		4		1,650
Service revenue - product related	—		60		60
Product sales	26		379		405
Product sales - related parties	9		68		77
Total revenues from contracts with customers	$	1,846	$	1,579	3,425
Non-ASC 606 revenue(1)					1,020
Total revenues and other income					$	4,445

(1) Non-ASC 606 Revenue includes rental income, income/(loss) from equity method investments, derivative gains and losses, mark-to-market adjustments, and other income.

(2) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

Contract Balances

Contract assets typically relate to aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer or for deficiency payments associated with minimum volume commitments which have not been billed to customers. Contract assets are generally classified as current and included in “Other current assets” on the Consolidated Balance Sheets.

Contract liabilities, which we refer to as “Deferred revenue” and “Long-term deferred revenue,” typically relate to advance payments for aid in construction agreements and deferred customer credits associated with makeup rights and minimum volume commitments. Related to minimum volume commitments, breakage is estimated and recognized into service revenue in instances where it is probable the customer will not use the credit in future periods. We classify contract liabilities as current or long-term based on the timing of when we expect to recognize revenue.

“Receivables, net” primarily relate to our commodity sales. Portions of the “Receivables, net” balance are attributed to the sale of commodity product controlled by MPLX prior to sale while a significant portion of the balance relates to the sale of commodity product on behalf of our producer customers. Both types of transactions are commingled and excluded from the table below. MPLX remits the net sales price back to our producer customers upon completion of the sale. Each period end, certain amounts within accounts payable relate to our payments to producer customers. Such amounts are not deemed material at period end as a result of when we settle with each producer.

The tables below reflect the changes in our contract balances for the six-month periods ended June 30, 2020 and 2019:

(In millions)	Balance at December 31, 2019(1)		Additions/ (Deletions)			Revenue Recognized(2)			Balance at June 30, 2020
Contract assets	$	39	$	(20	)	$	(1	)	$	18
Deferred revenue	23		8			(5		)	26
Deferred revenue - related parties	53		48			(29		)	72
Long-term deferred revenue	90		11			—			101
Long-term deferred revenue - related parties	$	55	$	(2	)	$	—		$	53

(In millions)	Balance at December 31, 2018(1)		Additions/ (Deletions)(3)			Revenue Recognized(2)(3)			Balance at June 30, 2019(3)
Contract assets	$	36	$	(8	)	$	(1	)	$	27
Deferred revenue	13		4			(3		)	14
Deferred revenue - related parties	65		18			(30		)	53
Long-term deferred revenue	56		14			—			70
Long-term deferred revenue - related parties	$	52	$	(2	)	$	—		$	50

(1) Balance represents ASC 606 portion of each respective line item.

(2) No significant revenue was recognized related to past performance obligations in the current periods.

(3) Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

Remaining Performance Obligations

The table below includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period.

As of June 30, 2020, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $250 million and are reflected in the amounts below. This will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 31 years. Further, MPLX does not disclose variable consideration due to volume variability in the table below.

(In millions)
2020	$	938
2021	1,790
2022	1,759
2023	1,673
2024 and thereafter	5,915
Total revenue on remaining performance obligations(1),(2),(3)	$	12,075

(1) All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

(2) Arrangements deemed implicit leases are included in “Rental income” and are excluded from this table.

(3) Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

We do not disclose information on the future performance obligations for any contract with an original expected duration of

one year or less.

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Supplemental Cash Flow Information

6 Months Ended

Jun. 30, 2020

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information [Text Block]

Supplemental Cash Flow Information

	Six Months Ended June 30,
(In millions)	2020			2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	423		$	402
Income taxes paid	1			—
Non-cash investing and financing activities:
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	$	(1	)	$	1

The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that did not affect cash. The following is the change of additions to property, plant and equipment related to capital accruals:

	Six Months Ended June 30,
(In millions)	2020			2019
(Decrease)/increase in capital accruals	$	(172	)	$	(77	)

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Accumulated Other Comprehensive Income

6 Months Ended

Jun. 30, 2020

Accumulated Other Comprehensive Income (Loss) [Line Items]

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

Accumulated Other Comprehensive Loss

MPLX LP records an accumulated other comprehensive loss on the Consolidated Balance Sheets relating to pension and other post-retirement benefits provided by LOOP LLC (“LOOP”) and Explorer Pipeline Company (“Explorer”) to their employees. MPLX LP is not a sponsor of these benefit plans.

The following table shows the changes in “Accumulated other comprehensive loss” by component during the period December 31, 2019 through June 30, 2020.

(In millions)	Pension Benefits			Other Post-Retirement Benefits			Total
Balance at December 31, 2019(1)	$	(14	)	$	(1	)	$	(15	)
Other comprehensive loss - remeasurements(2)	—			(1		)	(1		)
Balance at June 30, 2020(1)	$	(14	)	$	(2	)	$	(16	)

The following table shows the changes in “Accumulated other comprehensive loss” by component during the period December 31, 2018 through June 30, 2019.

(In millions)	Pension Benefits			Other Post-Retirement Benefits			Total
Balance at December 31, 2018(1)	$	(14	)	$	(2	)	$	(16	)
Other comprehensive income - remeasurements(2)	—			1			1
Balance at June 30, 2019(1)	$	(14	)	$	(1	)	$	(15	)

(1) These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”

(2)

Components of other comprehensive income/loss - remeasurements relate to actuarial gains and losses as well as amortization of prior service costs. MPLX records an adjustment to “Comprehensive income” in accordance with its ownership interest in LOOP and Explorer.

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Equity-Based Compensation Plan

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Equity-Based Compensation Plan

Equity-Based Compensation

Phantom Units

The following is a summary of phantom unit award activity of MPLX LP common units for the six months ended June 30, 2020:

	Number of Units		Weighted Average Fair Value
Outstanding at December 31, 2019	1,109,568		$	35.97
Granted	195,461		19.43
Settled	(323,884	)	35.67
Forfeited	(4,627	)	36.40
Outstanding at June 30, 2020	976,518		$	32.76

Performance Units – MPLX grants performance units to certain officers of the general partner and certain eligible MPC officers who make significant contributions to its business. These performance units pay out 75 percent in cash and 25 percent in MPLX LP common units and often contain both market and performance conditions based on various metrics. Market conditions are valued using a Monte Carlo valuation while performance conditions are reevaluated periodically and valued at the compensation cost associated with the performance outcome deemed most probable. 

The performance units granted in 2020 are hybrid awards having a three-year performance period of January 1, 2020 through December 31, 2022. The payout of the award is dependent on two independent conditions, each constituting 50 percent of the overall target units granted. The awards have a performance condition based on MPLX LP’s distributable cash flow, and a market condition based on MPLX LP’s total unitholder return. The market condition was valued using a Monte Carlo valuation, resulting in a grant date fair value of $0.80 per unit for the 2020 equity-classified performance units. Grant date fair value of the performance condition is based on potential payouts per unit of up to $2.00 per unit. Compensation cost associated with the performance condition is based on the grant date fair value of the payout deemed most probable to occur and is adjusted as the expectation for payout changes.

During the first quarter of 2018, a performance award was granted; however, due to the nature of the award terms, the grant date for this award was not established until the first quarter of 2020 and we began recognizing units and expense related to this award at that time. The performance units granted in 2018 are hybrid awards having a three-year performance period of January 1, 2018 through December 31, 2020. The payout of the award is dependent on two independent conditions, each constituting 50 percent of the overall target units granted. The awards have a performance condition based on an average of MPLX LP’s distributable cash flow and a market condition based on MPLX LP’s total unitholder return. The market condition was valued using a Monte Carlo valuation, resulting in a grant date fair value of $0.45 per unit for the 2018 equity-classified performance units. Grant date fair value of the performance condition is based on potential payouts per unit of up to $2.00 per unit. Compensation cost associated with the performance condition is based on the grant date fair value of the payout deemed most probable to occur and is adjusted as the expectation for payout changes.

The following is a summary of the activity for performance unit awards to be settled in MPLX LP common units for the six months ended June 30, 2020:

	Number of Units
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	(1,169,354	)
Forfeited	(31,668	)
Outstanding at June 30, 2020	3,103,536

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Leases Leases (Notes)

6 Months Ended

Jun. 30, 2020

Disclosure Text Block [Abstract]

Leases of Lessor Disclosure [Text Block]

Leases

During the first quarter of 2020, reimbursements for projects at certain MPLX refining logistics locations were agreed to between MPLX and MPC. These reimbursements relate to the storage services agreements between MPLX and MPC at these locations and required the embedded leases within these agreements to be reassessed under the leasing standard. As a result of the reassessment, one of our leases was reclassified from an operating lease to a sales-type lease. As a result, the underlying assets previously shown on the Consolidated Balance Sheets associated with the sales-type lease were derecognized and the net investment in the lease (i.e., the sum of the present value of the future lease payments and the unguaranteed residual value of the assets) was recorded as a lease receivable. See Note 5 for the location of lease receivables and unguaranteed residual assets on the Consolidated Balance Sheets. The difference between the net book value of the underlying assets and the net investment in the lease has been recorded as a Contribution from MPC in the Consolidated Statements of Equity given that the transaction related to refining logistics was a common control transaction. During the first quarter of 2020, MPLX derecognized approximately $171 million of property, plant and equipment, recorded a lease receivable of approximately $370 million, recorded an unguaranteed residual asset of approximately $10 million and a Contribution from MPC of $209 million.

Lease revenues included on the Consolidated Statements of Income were as follows:

	Three Months Ended June 30, 2020				Three Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	195	$	66	$	246	$	68
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

	Six Months Ended June 30, 2020				Six Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	381	$	129	$	525	$	133
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	76		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

(1) These amounts are presented net of executory costs.

(2) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

See Note 5 for additional information on where related party lease assets are recorded in the Consolidated Balance Sheets. Third party lease assets are less than $1 million as of June 30, 2020 and are included within the “Receivables, net” and “Other noncurrent assets” captions within the Consolidated Balance Sheets.

The following is a schedule of future payments on the sales-type leases as of June 30, 2020:

(In millions)	Related Party
2020	$	78
2021	157
2022	157
2023	158
2024	158
2025 and thereafter	473
Total minimum future rentals	1,181
Less: present value discount	758
Lease receivable	$	423

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Commitments and Contingencies

6 Months Ended

Jun. 30, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]

Commitments and Contingencies

MPLX is the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which MPLX has not recorded an accrued liability, MPLX is unable to estimate a range of possible losses because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material.

Environmental Matters – MPLX is subject to federal, state and local laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for non-compliance.

At June 30, 2020 and December 31, 2019, accrued liabilities for remediation totaled $18 million and $19 million, respectively. However, it is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, which may be imposed. At June 30, 2020 and December 31, 2019, there were no balances with MPC for indemnification of environmental costs.

MPLX is involved in environmental enforcement matters arising in the ordinary course of business. While the outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these environmental matters will not, individually or collectively, have a material adverse effect on its consolidated results of operations, financial position or cash flows.

MPLX is also a party to a number of other lawsuits and other proceedings arising in the ordinary course of business. While the ultimate outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated results of operations, financial position or cash flows.

Guarantees – Over the years, MPLX has sold various assets in the normal course of its business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require MPLX to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. MPLX is typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based.

In connection with our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL, we have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, have agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system.

In March 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits for the Bakken Pipeline system, to conduct a full environmental impact statement (“EIS”), and further requested briefing on whether an easement permit necessary for the operation of the Bakken Pipeline system should be vacated while the EIS is being prepared.

On July 6, 2020, the D.D.C. ordered vacatur of the easement permit during the pendency of an EIS and further ordered shut down of the pipeline by August 5, 2020. The D.D.C. denied a motion to stay that order. Dakota Access and the Army Corps are appealing the D.D.C.’s order to the U.S. Court of Appeals for the District of Columbia Circuit. On July 14, 2020, the Circuit Court issued an administrative stay while the court considers Dakota Access and the Army Corps’ emergency motion for stay pending appeal.

If the pipeline is temporarily shutdown pending completion of the EIS, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the 1% redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of June 30, 2020, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $230 million.

Other Legal Proceedings – In early July, MPLX received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification covers the rights of way for 23 tracts of land and demands the immediate cessation of pipeline operations. The notification also assesses trespass damages of approximately $187 million. MPLX expects to receive a notification for an additional 11 tracts in the near future. We appealed this determination, which triggered an automatic stay of the requested pipeline shutdown and payment. We believe the trespass damage calculation is dependent on a novel interpretation of the applicable law, and we continue to actively negotiate settlement of this matter with holders of the property rights at issue. Management does not believe the ultimate resolution of this matter will have a material adverse effect on our consolidated financial position, results of operations, or cash flows.

Contractual Commitments and Contingencies – At June 30, 2020, MPLX’s contractual commitments to acquire property, plant and equipment totaled $293 million. These commitments were primarily related to G&P plant expansion, terminal and pipeline projects. In addition, from time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of June 30, 2020, management does not believe there are any indications that MPLX will not be able to meet the construction milestones, that force majeure does not apply or that such fees and charges will otherwise be triggered.

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Subsequent Events Subsequent Events (Notes)

6 Months Ended

Jun. 30, 2020

Subsequent Event [Line Items]

Subsequent Events [Text Block]

Subsequent Events

On July 31, 2020, MPLX entered into a Redemption Agreement (the “Redemption Agreement”) with Western Refining Southwest, Inc., an Arizona corporation (“WRSW”) and wholly owned subsidiary of MPC, pursuant to which MPLX agreed to transfer to WRSW all of the outstanding membership interests in Western Refining Wholesale, LLC, a Delaware limited liability company (“WRW”) to WRSW in exchange for the redemption of MPLX common units held by WRSW. The transaction effects the transfer to MPC of the Western wholesale distribution business that MPLX acquired as a result of its acquisition of ANDX. The Redemption Agreement was approved by the conflicts committee and the board of directors of MPLX’s general partner. The conflicts committee, which is composed of independent members of the board of directors of MPLX’s general partner, retained independent legal and financial advisors to assist it in evaluating and negotiating the transaction.

Per the terms of Redemption Agreement, MPLX redeemed 18,582,088 Common Units (the “Redeemed Units”) held by WRSW on July 31, 2020. The number of Redeemed Units was calculated by dividing WRW’s aggregate valuation of $340 million by the simple average of the volume weighted average New York Stock Exchange prices of an MPLX Common Unit for the ten trading days ending at market close on July 27, 2020.

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Description of the Business and Basis of Presentation Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Business Description and Basis of Presentation [Text Block]

Description of the Business and Basis of Presentation

Description of the Business – MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to “MPC” refer collectively to Marathon Petroleum Corporation as our sponsor and its subsidiaries, other than the Partnership. We are engaged in the transportation, storage and distribution of crude oil, asphalt and refined petroleum products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.

MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, asphalt and refined petroleum products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 9 for additional information regarding the operations and results of these segments.

On July 30, 2019, MPLX completed its acquisition by merger (the “Merger”) of Andeavor Logistics LP (“ANDX”). At the effective time of the Merger, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. See Note 3 for additional information regarding the Merger.

Impairments – The outbreak of COVID-19 and its development into a pandemic in March 2020 resulted in significant economic disruption globally. Actions taken by various governmental authorities, individuals and companies around the world to prevent the spread of COVID-19 through social distancing have restricted travel, many business operations, public gatherings and the overall level of individual movement and in-person interaction across the globe. Although there have been some signs of economic improvement, these events significantly reduced global economic activity and resulted in a decline in the demand for the midstream services we provide beginning with the first quarter of 2020. Macroeconomic conditions and global geopolitical events have also resulted in significant price volatility related to those aforementioned products.

The overall deterioration in the economy and the environment in which MPLX and its customers operate, as well as a sustained decrease in unit price, were considered triggering events resulting in impairments of the carrying value of certain assets during the first quarter of 2020. We recognized impairments related to goodwill, certain equity method investments and certain long-lived assets (including intangibles), within our G&P segment. Many of our producer customers refined and updated production forecasts in response to the current environment, which impacted their current and expected future demand for our services, including the future utilization of our assets. Additionally, certain of our contracts have commodity price exposure, including NGL prices, which have experienced increased volatility as noted above. The table below provides information related to the impairments recognized during the first quarter of 2020 as well as the corresponding footnote where additional information can be found. No additional events or circumstances arose during the second quarter of 2020 which would indicate the need for any additional impairment beyond those recognized during the first quarter.

(In millions)	Impairment		Footnote Reference
Goodwill	$	1,814	12
Equity method investments	1,264		4
Intangibles, net	177		12
Property, plant and equipment, net	174		11
Total impairments	$	3,429

Basis of Presentation – The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain amounts in prior years have been reclassified to conform to current year presentation.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Annual Report on Form 10-K for the year ended December 31, 2019. The results of

operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results to be expected for the full year.

In relation to the Merger described above and in Note 3, ANDX’s assets, liabilities and results of operations prior to the Merger are collectively included in what we refer to as the “Predecessor” from October 1, 2018, which was the date that MPC acquired Andeavor. MPLX’s acquisition of ANDX is considered a transfer between entities under common control due to MPC’s relationship with ANDX prior to the Merger. As an entity under common control with MPC, MPLX recorded the assets acquired and liabilities assumed on its consolidated balance sheets at MPC’s historical carrying value. Transfers of businesses between entities under common control require prior periods to be retrospectively adjusted for those dates that the entity was under common control. Accordingly, the accompanying financial statements and related notes of MPLX LP have been retrospectively adjusted to include the historical results of ANDX beginning October 1, 2018.

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule. Distributions, although earned, are not accrued until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 6.

Use of Estimates, Policy [Policy Text Block]

The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain amounts in prior years have been reclassified to conform to current year presentation.

Earnings Per Share, Policy [Policy Text Block]

In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule. Distributions, although earned, are not accrued until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 6.

Net income/(loss) per unit applicable to common units is computed by dividing net income/(loss) attributable to MPLX LP less income/(loss) allocated to participating securities by the weighted average number of common units outstanding. Additional MPLX common units, MPLX Series B preferred units, and TexNew Mex units were issued on July 30, 2019 as a result of the merger with ANDX as discussed in Note 3. Distributions declared on these newly issued common and Series B preferred units are a reduction to income available to MPLX common unit holders due to their participation in distributions of income.

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Net Income Per Limited Partner Unit Accounting Policy (Policies)

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Earnings Per Share, Policy [Policy Text Block]

In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule. Distributions, although earned, are not accrued until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 6.

Net income/(loss) per unit applicable to common units is computed by dividing net income/(loss) attributable to MPLX LP less income/(loss) allocated to participating securities by the weighted average number of common units outstanding. Additional MPLX common units, MPLX Series B preferred units, and TexNew Mex units were issued on July 30, 2019 as a result of the merger with ANDX as discussed in Note 3. Distributions declared on these newly issued common and Series B preferred units are a reduction to income available to MPLX common unit holders due to their participation in distributions of income.

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Equity Method Investments (Tables)

6 Months Ended

Jun. 30, 2020

Schedule of Equity Method Investments [Line Items]

Equity Method Investments [Table Text Block]

The following table presents MPLX’s equity method investments at the dates indicated:

	Ownership as of	Carrying value at
	June 30,	June 30,		December 31,
(In millions, except ownership percentages)	2020	2020		2019
L&S
MarEn Bakken Company LLC(1)	25%	$	477	$	481
Illinois Extension Pipeline Company, L.L.C.	35%	268		265
LOOP LLC	41%	242		238
Andeavor Logistics Rio Pipeline LLC(2)	67%	196		202
Minnesota Pipe Line Company, LLC	17%	190		190
Whistler Pipeline LLC(2)	38%	188		134
Explorer Pipeline Company	25%	79		83
W2W Holdings LLC(2)(3)	50%	77		—
Wink to Webster Pipeline LLC(2)(3)	15%	—		126
Other(2)		60		55
Total L&S		1,777		1,774
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	725		1,984
Sherwood Midstream LLC(2)	50%	560		537
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	308		302
Rendezvous Gas Services, L.L.C.(2)	78%	166		170
Sherwood Midstream Holdings LLC(2)	51%	152		157
Centrahoma Processing LLC	40%	151		153
Other(2)		226		198
Total G&P		2,288		3,501
Total		$	4,065	$	5,275

(1) The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.    

(2) Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

(3) During the six months ended June 30, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

Summarized Financial Information For Equity Method Investees Table [Table Text Block]

Summarized financial information for MPLX’s equity method investments for the six months ended June 30, 2020 and 2019 is as follows:

	Six Months Ended June 30, 2020
(In millions)	VIEs			Non-VIEs		Total
Revenues and other income	$	(43	)	$	640	$	597
Costs and expenses	202			274		476
Income from operations	(245		)	366		121
Net income	(283		)	332		49
(Loss)/income from equity method investments(1)	$	(1,178	)	$	83	$	(1,095	)

(1) Includes the impact of any basis differential amortization or accretion in addition to the impairment of $1,264 million.

	Six Months Ended June 30, 2019(1)
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	306	$	724	$	1,030
Costs and expenses	159		295		454
Income from operations	147		429		576
Net income	127		383		510
Income from equity method investments(2)	$	54	$	106	$	160

(1) Financial information for the first six months of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Includes the impact of any basis differential amortization or accretion.

Summarized balance sheet information for MPLX’s equity method investments as of June 30, 2020 and December 31, 2019 is as follows:

	June 30, 2020
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	357	$	317	$	674
Noncurrent assets	5,824		5,061		10,885
Current liabilities	265		181		446
Noncurrent liabilities	$	656	$	853	$	1,509

	December 31, 2019
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	534	$	330	$	864
Noncurrent assets	5,862		5,134		10,996
Current liabilities	192		245		437
Noncurrent liabilities	$	305	$	822	$	1,127

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Related Party Agreements and Transactions (Tables)

6 Months Ended

Jun. 30, 2020

Related Party Transactions [Abstract]

Other Long-term Debt, Noncurrent

Activity on the MPC Loan Agreement was as follows:

(In millions)	Six Months Ended June 30, 2020			Year Ended December 31, 2019
Borrowings	$	2,708		$	8,540
Average interest rate of borrowings	2.733		%	3.441		%
Repayments	$	3,302		$	7,946
Outstanding balance at end of period(1)	$	—		$	594

(1) Included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

Prior to the Merger, ANDX was also party to a loan agreement with MPC (“ANDX-MPC Loan Agreement”). This facility was entered into on December 21, 2018, with a borrowing capacity of $500 million. In connection with the Merger, on July 31, 2019, MPLX repaid the entire outstanding balance and terminated the ANDX-MPC Loan Agreement. Activity on the ANDX-MPC Loan Agreement prior to the Merger was as follows:

(In millions)	Year Ended December 31, 2019
Borrowings	$	773
Average interest rate of borrowings	4.249		%
Repayments	$	773
Outstanding balance at end of period	$	—

Schedule of Sales to Related Parties

Revenue received from related parties included on the Consolidated Statements of Income was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Service revenues - related parties
MPC	$	857	$	847	$	1,784	$	1,650
Other	—		—		1		—
Total Service revenue - related parties	857		847		1,785		1,650
Rental income - related parties
MPC	237		286		471		611
Product sales - related parties(1)
MPC	30		36		63		77
Other income - related parties
MPC	48		10		96		20
Other	15		17		31		33
Total Other income - related parties	$	63	$	27	$	127	$	53

(1) There were additional product sales to MPC that net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and six months ended June 30, 2020, these sales totaled $52 million and $225 million. For the three and six months ended June 30, 2019, these sales totaled $295 million and $518 million.

Schedule of Employee Services Expenses from Related Parties

Expenses incurred from MPC under the omnibus and employee services agreements as well as other purchases from MPC included on the Consolidated Statements of Income are as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Rental cost of sales - related parties
MPC	$	41	$	36	$	87	$	79
Purchases - related parties
MPC	276		308		547		581
Other	4		5		9		10
Total Purchase - related parties	280		313		556		591
General and administrative expenses
MPC	$	68	$	53	$	132	$	115

Schedule of Related Party Transactions [Table Text Block]

(In millions)	June 30, 2020		December 31, 2019
Current assets - related parties
Receivables - MPC	$	547	$	621
Receivables - Other	7		22
Prepaid - MPC	11		9
Other - MPC	1		—
Lease Receivables - MPC	28		4
Total	594		656
Noncurrent assets - related parties
Long-term receivables - MPC	30		21
Right of use assets - MPC	231		232
Long-term lease receivables - MPC	395		43
Unguaranteed residual asset - MPC	20		7
Total	676		303
Current liabilities - related parties
Payables - MPC	260		911
Payables - Other	36		37
Operating lease liabilities - MPC	1		1
Deferred revenue - Minimum volume deficiencies - MPC	56		42
Deferred revenue - Project reimbursements - MPC	18		16
Deferred revenue - Project reimbursements - Other	1		1
Total	372		1,008
Long-term liabilities - related parties
Long-term operating lease liabilities - MPC	230		230
Long-term deferred revenue - Project reimbursements - MPC	51		53
Long-term deferred revenue - Project reimbursements - Other	6		7
Total	$	287	$	290

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Net Income Per Limited Partner Unit (Tables)

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Schedule of Distributions By Partner By Class

For the three and six months ended June 30, 2020 and 2019, MPLX had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three and six months ended June 30, 2020 and 2019 were less than 1 million.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019			2020			2019
Net income/(loss) attributable to MPLX LP	$	648		$	482		$	(2,076	)	$	985
Less: Distributions declared on Series A preferred units(1)	21			21			41			41
Distributions declared on Series B preferred units(1)	10			21			21			21
Limited partners’ distributions declared on MPLX common units (including common units of general partner)(1)(2)	715			692			1,443			1,215
Undistributed net loss attributable to MPLX LP	$	(98	)	$	(252	)	$	(3,581	)	$	(292	)

(1) See Note 7 for distribution information.

(2) The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

	Three Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	715		$	21	$	10	$	746
Undistributed net loss attributable to MPLX LP	(98		)	—		—		(98		)
Net income attributable to MPLX LP(1)	$	617		$	21	$	10	$	648
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.58
Diluted	$	0.58

Schedule of Basic and Diluted Earnings Per Unit

	Three Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	715		$	21	$	10	$	746
Undistributed net loss attributable to MPLX LP	(98		)	—		—		(98		)
Net income attributable to MPLX LP(1)	$	617		$	21	$	10	$	648
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.58
Diluted	$	0.58

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Three Months Ended June 30, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	692		$	21	$	21	$	734
Undistributed net loss attributable to MPLX LP	(252		)	—		—		(252		)
Net income attributable to MPLX LP(1)	$	440		$	21	$	21	$	482
Weighted average units outstanding:
Basic(2)	794
Diluted(2)	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.56
Diluted	$	0.55

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

(2) The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the three months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

	Six Months Ended June 30, 2020
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,443		$	41	$	21	$	1,505
Undistributed net loss attributable to MPLX LP	(3,581		)	—		—		(3,581		)
Net (loss)/income attributable to MPLX LP(1)	$	(2,138	)	$	41	$	21	$	(2,076	)
Weighted average units outstanding:
Basic	1,059
Diluted	1,059
Net income attributable to MPLX LP per limited partner unit:
Basic	$	(2.02	)
Diluted	$	(2.02	)

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Six Months Ended June 30, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,215		$	41	$	21	$	1,277
Undistributed net loss attributable to MPLX LP	(292		)	—		—		(292		)
Net income attributable to MPLX LP(1)	$	923		$	41	$	21	$	985
Weighted average units outstanding:
Basic(2)	794
Diluted(2)	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.16
Diluted	$	1.16

(1) Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

(2)

The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the six months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

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Equity (Tables)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Schedule of Stockholders Equity [Table Text Block]

The changes in the number of common units outstanding during the six months ended June 30, 2020 are summarized below:

(In units)	Common
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	253,291
Balance at June 30, 2020	1,058,608,762

Merger

In connection with the Merger and as discussed in Note 3, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units while ANDX common units held by certain affiliates of MPC were converted into the right to receive 1.0328 MPLX common units. This resulted in the issuance of MPLX common units of approximately 102 million units to public unitholders and approximately 161 million units to MPC on July 30, 2019.

Series B Preferred Units

Prior to the Merger, ANDX had outstanding 600,000 units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of ANDX at a price to the public of $1,000 per unit. Upon completion of the Merger, the ANDX preferred units converted to preferred units of MPLX representing substantially equivalent limited partnership interests in MPLX (the “Series B preferred units”). The Series B preferred units are pari passu with the Series A preferred units with respect to distribution rights and rights upon liquidation. Distributions on the Series B preferred units are payable semi-annually in arrears on the 15th day, or the first business day thereafter, of February and August of each year up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent.

The changes in the Series B preferred unit balance from December 31, 2019 through June 30, 2020 are summarized below. Series B preferred units are included in the Consolidated Balance Sheets and Consolidated Statements of Equity within “Equity of Predecessor” for the period prior to the Merger and within “Series B preferred units” for the period following the Merger.

(In millions)	Series B Preferred Units
Balance at December 31, 2019	$	611
Net income allocated	21
Distributions received by Series B preferred unitholders	(21		)
Balance at June 30, 2020	$	611

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

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and six months ended June 30, 2020 and 2019. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019		2020		2019
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	715	$	692	$	1,443	$	1,215
Series A preferred unit distributions	21		21		41		41
Series B preferred unit distributions	10		21		21		21
Total cash distributions declared	$	746	$	734	$	1,505	$	1,277

The distribution on common units for the three and six months ended June 30, 2019 includes the impact of the issuance of approximately 102 million units issued to public unitholders and approximately 161 million units issued to MPC in connection with the Merger. Due to the timing of the closing, distributions presented in the table above include second quarter distributions on MPLX common units issued to former ANDX unitholders and Series B Unitholders in connection with the Merger. The distributions on common units exclude $12.5 million of waived distributions for the three and six months ended June 30, 2019.

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Series A Preferred Units (Tables)

6 Months Ended

Jun. 30, 2020

Temporary Equity Disclosure [Abstract]

Rollforward of Redeemable Preferred Units

The changes in the redeemable preferred balance from December 31, 2019 through June 30, 2020 are summarized below:

(In millions)	Redeemable Series A Preferred Units
Balance at December 31, 2019	$	968
Net income allocated	41
Distributions received by Series A preferred unitholders	(41		)
Balance at June 30, 2020	$	968

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Segment Information (Tables)

6 Months Ended

Jun. 30, 2020

Segment Reporting [Abstract]

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

The tables below present information about revenues and other income, capital expenditures and investments in unconsolidated affiliates as well as total assets for our reportable segments:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2020		2019(1)		2020			2019(1)
L&S
Service revenue	$	931	$	922	$	1,935		$	1,811
Rental income	246		296		488			631
Product related revenue	21		20		40			35
Income from equity method investments	40		54		90			99
Other income	52		16		103			28
Total segment revenues and other income(2)	1,290		1,308		2,656			2,604
Segment Adjusted EBITDA(3)	839		570		1,711			1,129
Capital expenditures	108		230		292			428
Investments in unconsolidated affiliates	74		61		128			68
G&P
Service revenue	489		544		1,025			1,072
Rental income	89		83		177			172
Product related revenue	151		231		373			507
Income/(loss) from equity method investments	49		29		(1,185		)	61
Other income	13		15		27			29
Total segment revenues and other (loss)/income(2)	791		902		417			1,841
Segment Adjusted EBITDA(3)	388		350		810			721
Capital expenditures	110		326		244			632
Investments in unconsolidated affiliates	$	57	$	127	$	94		$	255

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

(3)

See below for the reconciliation from Segment Adjusted EBITDA to net income.

Reconciliation of Assets from Segment to Consolidated [Table Text Block]

(In millions)	June 30, 2020		December 31, 2019
Segment assets
Cash and cash equivalents	$	67	$	15
L&S	21,308		20,810
G&P	15,647		19,605
Total assets	$	37,022	$	40,430

Reconciliation of Other Significant Reconciling Items from Segments to Consolidated [Table Text Block]

The table below provides a reconciliation between net (loss)/income and Segment Adjusted EBITDA.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019(1)			2020			2019(1)
Reconciliation to Net (loss)/income:
L&S Segment Adjusted EBITDA	$	839		$	570		$	1,711		$	1,129
G&P Segment Adjusted EBITDA	388			350			810			721
Total reportable segments	1,227			920			2,521			1,850
Depreciation and amortization(2)	(321		)	(313		)	(646		)	(614		)
Benefit for income taxes	—			1			—			2
Amortization of deferred financing costs	(15		)	(12		)	(29		)	(19		)
Non-cash equity-based compensation	(3		)	(5		)	(8		)	(12		)
Impairment expense	—			—			(2,165		)	—
Net interest and other financial costs	(208		)	(217		)	(424		)	(434		)
Income/(loss) from equity method investments	89			83			(1,095		)	160
Distributions/adjustments related to equity method investments	(115		)	(132		)	(239		)	(254		)
Unrealized derivative (losses)/gains(3)	(6		)	—			9			(4		)
Acquisition costs	—			(4		)	—			(5		)
Other	(1		)	—			(2		)	—
Adjusted EBITDA attributable to noncontrolling interests	8			7			17			14
Adjusted EBITDA attributable to Predecessor(4)	—			329			—			662
Net (loss)/income	$	655		$	657		$	(2,061	)	$	1,346

(1) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

(2) Depreciation and amortization attributable to L&S was $138 million and $276 million for the three and six months ended June 30, 2020, respectively, and $134 million and $260 million for the three and six months ended June 30, 2019, respectively. Depreciation and amortization attributable to G&P was $183 million and $370 million for the three and six months ended June 30, 2020, respectively, and $179 million and $354 million for the three and six months ended June 30, 2019, respectively.

(3) MPLX makes a distinction between realized and unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded.

(4)

The adjusted EBITDA adjustments related to Predecessor are excluded from adjusted EBITDA attributable to MPLX LP prior to the Merger.

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Inventories (Tables)

6 Months Ended

Jun. 30, 2020

Inventory Disclosure [Abstract]

Summary of Inventories

Inventories consist of the following:

(In millions)	June 30, 2020		December 31, 2019
NGLs	$	2	$	5
Line fill	8		10
Spare parts, materials and supplies	105		95
Total inventories	$	115	$	110

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Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2020

Property, Plant and Equipment [Abstract]

Summary of Property, Plant and Equipment

Property, plant and equipment with associated accumulated depreciation is shown below:

(In millions)	Estimated Useful Lives	June 30, 2020		December 31, 2019
L&S
Pipelines	2-51 years	$	5,719	$	5,572
Refining Logistics	13-40 years	2,324		2,870
Terminals	4-40 years	1,281		1,109
Marine	15-20 years	960		906
Land, building and other	1-61 years	1,834		1,817
Construction-in progress		520		660
Total L&S property, plant and equipment		12,638		12,934
G&P
Gathering and transportation	5-40 years	7,374		7,159
Processing and fractionation	15-40 years	5,923		5,545
Land, building and other	3-40 years	489		484
Construction-in-progress		368		745
Total G&P property, plant and equipment		14,154		13,933
Total property, plant and equipment		26,792		26,867
Less accumulated depreciation(1)		5,034		4,722
Property, plant and equipment, net		$	21,758	$	22,145

(1) The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020 as discussed below.

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Goodwill and Intangibles (Tables)

6 Months Ended

Jun. 30, 2020

Finite-Lived Intangible Assets [Line Items]

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

Gross intangible assets with accumulated amortization as of June 30, 2020 and December 31, 2019 is shown below:

		June 30, 2020							December 31, 2019
(In millions)	Useful Life	Gross		Accumulated Amortization(1)(2)			Net		Gross		Accumulated Amortization			Net
L&S	6 - 8 years	$	283	$	(63	)	$	220	$	283	$	(45	)	$	238
G&P	6 - 25 years	1,288		(485		)	803		1,288		(256		)	1,032
		$	1,571	$	(548	)	$	1,023	$	1,571	$	(301	)	$	1,270

(1) Amortization expense attributable to the G&P and L&S segments for the six months ended June 30, 2020 was $52 million and $18 million, respectively.

(2)

Impairment charge of $177 million is included within the G&P accumulated amortization.

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

Estimated future amortization expense related to the intangible assets at June 30, 2020 is as follows:

(In millions)
2020	$	64
2021	128
2022	128
2023	128
2024	124
Thereafter	451
Total	$	1,023

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Goodwill and Intangibles Goodwill and Intangibles (Tables)

6 Months Ended

Jun. 30, 2020

Goodwill [Line Items]

Schedule of Goodwill [Table Text Block]

The changes in carrying amount of goodwill were as follows:

(In millions)	L&S		G&P			Total
Gross goodwill as of December 31, 2018	$	7,234	$	2,912		$	10,146
Accumulated impairment losses	—		(130		)	(130		)
Balance as of December 31, 2018	7,234		2,782			10,016
Impairment losses	—		(1,197		)	(1,197		)
Acquisitions	488		229			717
Balance as of December 31, 2019	7,722		1,814			9,536
Impairment losses	—		(1,814		)	(1,814		)
Balance as of June 30, 2020	7,722		—			7,722
Gross goodwill as of June 30, 2020	7,722		3,141			10,863
Accumulated impairment losses	—		(3,141		)	(3,141		)
Balance as of June 30, 2020	$	7,722	$	—		$	7,722

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Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following table presents the financial instruments carried at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 by fair value hierarchy level. MPLX has elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty.

	June 30, 2020					December 31, 2019
(In millions)	Assets		Liabilities			Assets		Liabilities
Significant unobservable inputs (Level 3)
Embedded derivatives in commodity contracts	$	—	$	(51	)	$	—	$	(60	)
Total carrying value on Consolidated Balance Sheets	$	—	$	(51	)	$	—	$	(60	)

Fair Value Inputs Assets and Liabilities Quantitative Information [Table Text Block]

Level 3 instruments include all NGL transactions and embedded derivatives in commodity contracts. The embedded derivative liability relates to a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.38 to $0.92 per gallon with a weighted average of $0.53 per gallon per the current term of the embedded derivative and (2) the probability of renewal of 100 percent for the first five-year term and

second five-year term of the gas purchase commitment and related keep-whole processing agreement, respectively. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of June 30, 2020 or December 31, 2019.

Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

The following table is a reconciliation of the net beginning and ending balances recorded for net assets and liabilities classified as Level 3 in the fair value hierarchy.

	Three Months Ended June 30, 2020					Three Months Ended June 30, 2019
(In millions)	Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)			Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	—	$	(45	)	$	—	$	(65	)
Total (losses)/gains (realized and unrealized) included in earnings(1)	—		(7		)	—		(1		)
Settlements	—		1			—		1
Fair value at end of period	—		(51		)	—		(65		)
The amount of total (losses)/gains for the period included in earnings attributable to the change in unrealized gains/(losses) relating to liabilities still held at end of period	$	—	$	(6	)	$	—	$	(2	)

	Six Months Ended June 30, 2020					Six Months Ended June 30, 2019
(In millions)	Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)			Commodity Derivative Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	—	$	(60	)	$	—	$	(61	)
Total gains/(losses) (realized and unrealized) included in earnings(1)	—		7			—		(7		)
Settlements	—		2			—		3
Fair value at end of period	—		(51		)	—		(65		)
The amount of total gains/(losses) for the period included in earnings attributable to the change in unrealized gains/(losses) relating to liabilities still held at end of period	$	—	$	7		$	—	$	(5	)

(1) Gains and losses on commodity derivative contracts classified as Level 3 are recorded in “Product sales” on the Consolidated Statements of Income. Gains and losses on derivatives embedded in commodity contracts are recorded in “Purchased product costs” and “Cost of revenues” on the Consolidated Statements of Income.

Fair Value Carrying Value by Balance Sheet Grouping [Table Text Block]

The following table summarizes the fair value and carrying value of the long-term debt, excluding finance leases, and SMR liability:

	June 30, 2020				December 31, 2019
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-term debt	$	21,919	$	20,646	$	21,054	$	19,800
SMR liability	$	88	$	78	$	90	$	80

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Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

As of June 30, 2020, MPLX had no outstanding commodity contracts beyond the embedded derivative discussed below.

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

The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	June 30, 2020					December 31, 2019
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability			Asset		Liability
Commodity contracts(1)
Other current assets / Other current liabilities	$	—	$	(3	)	$	—	$	(5	)
Other noncurrent assets / Deferred credits and other liabilities	—		(48		)	—		(55		)
Total	$	—	$	(51	)	$	—	$	(60	)

(1)

Includes embedded derivatives in commodity contracts as discussed above.

Derivative Instruments, Gain (Loss) [Table Text Block]

The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2020			2019			2020			2019
Purchased product costs
Realized (loss)/gain	$	(1	)	$	(1	)	$	(2	)	$	(3	)
Unrealized (loss)/gain	(6		)	—			9			(4		)
Purchased product costs derivative (loss)/gain	(7		)	(1		)	7			(7		)
Total derivative (loss)/gain	$	(7	)	$	(1	)	$	7		$	(7	)

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Debt (Tables)

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Summary of Outstanding Borrowings

MPLX’s outstanding borrowings consist of the following:

(In millions)	June 30, 2020			December 31, 2019
MPLX LP:
Bank revolving credit facility	$	825		$	—
Term loan facility	1,000			1,000
Floating rate senior notes	2,000			2,000
Fixed rate senior notes	16,887			16,887
Consolidated subsidiaries:
MarkWest	23			23
ANDX	190			190
Financing lease obligations(1)	13			19
Total	20,938			20,119
Unamortized debt issuance costs	(100		)	(106		)
Unamortized discount/premium	(279		)	(300		)
Amounts due within one year	(3		)	(9		)
Total long-term debt due after one year	$	20,556		$	19,704

(1)    See Note 20 for lease information.

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Revenue (Tables)

6 Months Ended

Jun. 30, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

The following tables represent a disaggregation of revenue for each reportable segment for the three and six months ended June 30, 2020 and 2019:

	Three Months Ended June 30, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	77	$	486	$	563
Service revenue - related parties	854		3		857
Service revenue - product related	—		22		22
Product sales	17		103		120
Product sales - related parties	4		26		30
Total revenues from contracts with customers	$	952	$	640	1,592
Non-ASC 606 revenue(1)					489
Total revenues and other income					$	2,081

	Three Months Ended June 30, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	79	$	540	$	619
Service revenue - related parties	843		4		847
Service revenue - product related	—		26		26
Product sales	15		174		189
Product sales - related parties	5		31		36
Total revenues from contracts with customers	$	942	$	775	1,717
Non-ASC 606 revenue(1)					493
Total revenues and other income					$	2,210

	Six Months Ended June 30, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	161	$	1,014	$	1,175
Service revenue - related parties	1,774		11		1,785
Service revenue - product related	—		61		61
Product sales	32		257		289
Product sales - related parties	8		55		63
Total revenues from contracts with customers	$	1,975	$	1,398	3,373
Non-ASC 606 loss(1)					(300		)
Total revenues and other income					$	3,073

	Six Months Ended June 30, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	165	$	1,068	$	1,233
Service revenue - related parties	1,646		4		1,650
Service revenue - product related	—		60		60
Product sales	26		379		405
Product sales - related parties	9		68		77
Total revenues from contracts with customers	$	1,846	$	1,579	3,425
Non-ASC 606 revenue(1)					1,020
Total revenues and other income					$	4,445

(1) Non-ASC 606 Revenue includes rental income, income/(loss) from equity method investments, derivative gains and losses, mark-to-market adjustments, and other income.

(2) Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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

The tables below reflect the changes in our contract balances for the six-month periods ended June 30, 2020 and 2019:

(In millions)	Balance at December 31, 2019(1)		Additions/ (Deletions)			Revenue Recognized(2)			Balance at June 30, 2020
Contract assets	$	39	$	(20	)	$	(1	)	$	18
Deferred revenue	23		8			(5		)	26
Deferred revenue - related parties	53		48			(29		)	72
Long-term deferred revenue	90		11			—			101
Long-term deferred revenue - related parties	$	55	$	(2	)	$	—		$	53

(In millions)	Balance at December 31, 2018(1)		Additions/ (Deletions)(3)			Revenue Recognized(2)(3)			Balance at June 30, 2019(3)
Contract assets	$	36	$	(8	)	$	(1	)	$	27
Deferred revenue	13		4			(3		)	14
Deferred revenue - related parties	65		18			(30		)	53
Long-term deferred revenue	56		14			—			70
Long-term deferred revenue - related parties	$	52	$	(2	)	$	—		$	50

(1) Balance represents ASC 606 portion of each respective line item.

(2) No significant revenue was recognized related to past performance obligations in the current periods.

(3) Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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

As of June 30, 2020, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $250 million and are reflected in the amounts below. This will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 31 years. Further, MPLX does not disclose variable consideration due to volume variability in the table below.

(In millions)
2020	$	938
2021	1,790
2022	1,759
2023	1,673
2024 and thereafter	5,915
Total revenue on remaining performance obligations(1),(2),(3)	$	12,075

(1) All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

(2) Arrangements deemed implicit leases are included in “Rental income” and are excluded from this table.

(3)

Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

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Supplemental Cash Flow Information (Tables)

6 Months Ended

Jun. 30, 2020

Supplemental Cash Flow Elements [Abstract]

Summary of Supplemental Cash Flow Information [Table Text Block]

	Six Months Ended June 30,
(In millions)	2020			2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	423		$	402
Income taxes paid	1			—
Non-cash investing and financing activities:
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	$	(1	)	$	1

Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures [Table Text Block]

The following is the change of additions to property, plant and equipment related to capital accruals:

	Six Months Ended June 30,
(In millions)	2020			2019
(Decrease)/increase in capital accruals	$	(172	)	$	(77	)

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Accumulated Other Comprehensive Income (Tables)

6 Months Ended

Jun. 30, 2020

Accumulated Other Comprehensive Income (Loss) [Line Items]

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

The following table shows the changes in “Accumulated other comprehensive loss” by component during the period December 31, 2019 through June 30, 2020.

(In millions)	Pension Benefits			Other Post-Retirement Benefits			Total
Balance at December 31, 2019(1)	$	(14	)	$	(1	)	$	(15	)
Other comprehensive loss - remeasurements(2)	—			(1		)	(1		)
Balance at June 30, 2020(1)	$	(14	)	$	(2	)	$	(16	)

The following table shows the changes in “Accumulated other comprehensive loss” by component during the period December 31, 2018 through June 30, 2019.

(In millions)	Pension Benefits			Other Post-Retirement Benefits			Total
Balance at December 31, 2018(1)	$	(14	)	$	(2	)	$	(16	)
Other comprehensive income - remeasurements(2)	—			1			1
Balance at June 30, 2019(1)	$	(14	)	$	(1	)	$	(15	)

(1) These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”

(2)

Components of other comprehensive income/loss - remeasurements relate to actuarial gains and losses as well as amortization of prior service costs. MPLX records an adjustment to “Comprehensive income” in accordance with its ownership interest in LOOP and Explorer.

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Equity-Based Compensation Plan (Tables)

6 Months Ended

Jun. 30, 2020

Phantom Units

Equity Transactions And Share Based Compensation [Line Items]

Summary of Share-based Compensation, Restricted Stock Units Award Activity

The following is a summary of phantom unit award activity of MPLX LP common units for the six months ended June 30, 2020:

	Number of Units		Weighted Average Fair Value
Outstanding at December 31, 2019	1,109,568		$	35.97
Granted	195,461		19.43
Settled	(323,884	)	35.67
Forfeited	(4,627	)	36.40
Outstanding at June 30, 2020	976,518		$	32.76

Performance Shares [Member]

Equity Transactions And Share Based Compensation [Line Items]

Summary of Share-based Compensation, Restricted Stock Units Award Activity

The following is a summary of the activity for performance unit awards to be settled in MPLX LP common units for the six months ended June 30, 2020:

	Number of Units
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	(1,169,354	)
Forfeited	(31,668	)
Outstanding at June 30, 2020	3,103,536

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Leases Lessor Disclosure (Tables)

6 Months Ended

Jun. 30, 2020

Lessor Disclosure [Abstract]

Operating Lease, Lease Income [Table Text Block]

Lease revenues included on the Consolidated Statements of Income were as follows:

	Three Months Ended June 30, 2020				Three Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	195	$	66	$	246	$	68
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

	Six Months Ended June 30, 2020				Six Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	381	$	129	$	525	$	133
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	76		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

(1) These amounts are presented net of executory costs.

(2)

Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

Sales-type Lease, Lease Income [Table Text Block]

Lease revenues included on the Consolidated Statements of Income were as follows:

	Three Months Ended June 30, 2020				Three Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	195	$	66	$	246	$	68
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

	Six Months Ended June 30, 2020				Six Months Ended June 30, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	381	$	129	$	525	$	133
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		—		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	76		—		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	$	—	N/A		N/A

(1) These amounts are presented net of executory costs.

(2)

Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

Sales-type and Direct Financing Leases, Lease Receivable, Maturity [Table Text Block]

The following is a schedule of future payments on the sales-type leases as of June 30, 2020:

(In millions)	Related Party
2020	$	78
2021	157
2022	157
2023	158
2024	158
2025 and thereafter	473
Total minimum future rentals	1,181
Less: present value discount	758
Lease receivable	$	423

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Description of Business and Basis of Presentation - Additional Information (Detail) $ in Millions		3 Months Ended	6 Months Ended	12 Months Ended
	Jul. 30, 2019 shares	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Description Of Business And Basis Of Presentation [Line Items]
Goodwill, Impairment Loss			$ 1,814	$ 1,197
Equity Method Investment, Other than Temporary Impairment		$ 1,264	$ 1,264
Impairment of Intangible Assets, Finite-lived		177
Number of reportable segments			2
Impairment of Long-Lived Assets Held-for-use		174
Impairment Charges		3,429
G&P
Description Of Business And Basis Of Presentation [Line Items]
Goodwill, Impairment Loss		$ 1,814	$ 1,814	$ 1,197
ANDX LP [Member] | Public
Description Of Business And Basis Of Presentation [Line Items]
Common Units Conversion Ratio - ANDX to MPLX | shares	1.135
ANDX LP [Member] | Nonpublic [Member]
Description Of Business And Basis Of Presentation [Line Items]
Common Units Conversion Ratio - ANDX to MPLX | shares	1.0328

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Accounting Standards Impact of Adoption (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Receivables, net	$ 562	$ 593
Accounts Receivable, Allowance for Credit Loss	$ 1

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Acquisitions Andeavor Logistics (Details) - USD ($) $ in Millions			3 Months Ended				6 Months Ended
		Jul. 30, 2019	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019		Mar. 31, 2020	Dec. 31, 2019	Sep. 09, 2019	Mar. 31, 2019	[9]	Dec. 31, 2018
Business Acquisition [Line Items]
Cash and cash equivalents			$ 67				$ 67					$ 15
Receivables, net			562				562					593
Inventories			115				115					110
Other current assets			48				48					110
Assets, Current			1,386				1,386					1,484
Equity method investments			4,065				4,065					5,275
Property, plant and equipment, net			21,758				21,758					22,145
Intangibles, net			1,023				1,023					1,270
Other noncurrent assets			51				51					52
Assets			37,022				37,022					40,430
Accounts payable			145				145					242
Accrued Liabilities, Current			138				138					187
Accrued interest payable			207				207					210
Other current liabilities			143				143					136
Liabilities, Current			1,228				1,228					2,132
Long-term deferred revenue			261				261					217
Liabilities, Related Parties, Noncurrent			287				287					290
Long-term debt			20,556				20,556					19,704
Deferred credits and other liabilities			175				175					192
Liabilities			22,792				22,792					22,849
Series A preferred units			968				968					968
Total MPLX LP partners’ capital			13,015				13,015					16,364
Accumulated other comprehensive loss	[1]		(16)		$ (15)		(16)		$ (15)			(15)				$ (16)
Revenues			2,081		2,210	[2],[3]	3,073		4,445	[2],[3]
Goodwill			7,722				7,722				$ 7,700	9,536				10,016
Net Income (Loss) Attributable to Parent			648	[4]	482	[2],[5]	(2,076)	[6]	985	[2],[7]
Acquisition Costs, Period Cost			0		4	[8]	0		5
Noncontrolling interests			247				247					249
Partners' Capital, Including Portion Attributable to Noncontrolling Interest			13,262		17,611		13,262		17,611		$ 13,356	16,613		$ 17,730		17,731
Liabilities and Equity			37,022				37,022					40,430
Net (loss)/income			655		657	[2],[8],[10]	(2,061)		1,346	[2],[10],[11]
Andeavor Logistics [Member]
Business Acquisition [Line Items]
Revenues					588				1,177
Acquisition Costs, Period Cost									5
Net (loss)/income					$ 168				$ 348
ANDX LP [Member] | Public
Business Acquisition [Line Items]
Common Units Conversion Ratio - ANDX to MPLX		1.135
ANDX LP [Member] | Nonpublic [Member]
Business Acquisition [Line Items]
Common Units Conversion Ratio - ANDX to MPLX		1.0328
Senior Notes [Member]
Business Acquisition [Line Items]
Long-term Debt, Gross													$ 2,000
L&S
Business Acquisition [Line Items]
Intangibles, net			220				220					238
Goodwill			7,722				$ 7,722					7,722				7,234
L&S | Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life							6 years
L&S | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life							8 years
G&P
Business Acquisition [Line Items]
Intangibles, net			803				$ 803					1,032
Goodwill			$ 0				$ 0					$ 1,814				$ 2,782
G&P | Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life							6 years
G&P | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life							25 years

[1] These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[5] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[6] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[7] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[8] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[9] Financial information for the first and second quarters of 2019 has been retrospectively adjusted for the acquisition of ANDX.

[10] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[11] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Equity Method Investments - Summary of Equity Method Investment Financial Information (Details) - USD ($) $ in Millions		3 Months Ended					6 Months Ended
		Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019		Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Revenues		$ 2,081			$ 2,210	[1],[2]	$ 3,073		$ 4,445	[1],[2]
Equity method investments		4,065					4,065				$ 5,275
Costs and Expenses		1,203			1,325	[1]	4,681		2,648	[1]
Net (loss)/income		655			657	[1],[3],[4]	(2,061)		1,346	[1],[3],[5]
Income/(loss) from equity method investments(2)		89			83	[1],[4]	(1,095)	[6],[7]	160	[1],[5]
Assets, Current		1,386					1,386				1,484
Liabilities, Current		$ 1,228					1,228				2,132
Equity Method Investment, Other than Temporary Impairment				$ 1,264			$ 1,264
MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%					25.00%
Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35.00%					35.00%
LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41.00%					41.00%
Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38.00%					38.00%
W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%					50.00%
Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		15.00%					15.00%
Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%					25.00%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57.00%					57.00%
Equity Method Investment, Other than Temporary Impairment				$ 1,251
Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%					50.00%
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%					67.00%
Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40.00%					40.00%
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		9.19%					9.19%
Indirect Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.47%					24.47%
Direct Ownership Interest [Member] | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%					67.00%
Direct Ownership Interest [Member] | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17.00%					17.00%
Direct Ownership Interest [Member] | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		78.00%					78.00%
Direct Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		51.00%					51.00%
G&P
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		$ (59)					$ (59)				1,000
Difference between carrying amount and underlying equity portion related to goodwill		31					31				498
G&P | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	725					725				1,984
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	560					560				537
G&P | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	308					308				302
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	166					166				170
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	152					152				157
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		151					151				153
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	226					226				198
L&S
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		330					330				329
Difference between carrying amount and underlying equity portion related to goodwill		167					167				167
L&S | MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[9]	477					477				481
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		268					268				265
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		242					242				238
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	196					196				202
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		190					190				190
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	188					188				134
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		77					77				0	[8],[10]
L&S | Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8],[10]	0					0				126
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		79					79				83
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	60					60				55
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Revenues		791	[11]		902	[4],[11]	417		1,841
Equity method investments		2,288					2,288				3,501
Income/(loss) from equity method investments(2)		49			29	[4]	(1,185)		61
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Revenues		1,290	[11]		1,308	[4],[11]	2,656		2,604
Equity method investments		1,777					1,777				1,774
Income/(loss) from equity method investments(2)		40			$ 54	[4]	90		99
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues							597		1,030
Costs and Expenses							476		454
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							121		576
Net (loss)/income							49		510
Income/(loss) from equity method investments(2)							(1,095)	[12]	160	[13]
Assets, Current		674					674				864
Assets, Noncurrent		10,885					10,885				10,996
Liabilities, Current		446					446				437
Liabilities, Noncurrent		1,509					1,509				1,127
Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues							640		724	[14]
Costs and Expenses							274		295	[14]
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							366		429	[14]
Net (loss)/income							332		383	[14]
Income/(loss) from equity method investments(2)							83	[12]	106	[13],[14]
Assets, Current		317					317				330
Assets, Noncurrent		5,061					5,061				5,134
Liabilities, Current		181					181				245
Liabilities, Noncurrent		853					853				822
Other VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues							(43)		306	[14]
Costs and Expenses							202		159	[14]
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							(245)		147	[14]
Net (loss)/income							(283)		127	[14]
Income/(loss) from equity method investments(2)							(1,178)	[12]	$ 54	[13],[14]
Assets, Current		357					357				534
Assets, Noncurrent		5,824					5,824				5,862
Liabilities, Current		265					265				192
Liabilities, Noncurrent		$ 656					$ 656				$ 305

[1] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[6] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[7] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

[8] Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

[9] The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.

[10] During the six months ended June 30, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

[11] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

[12] Includes the impact of any basis differential amortization or accretion in addition to the impairment of $1,264 million.

[13] Includes the impact of any basis differential amortization or accretion.

[14] Financial information for the first six months of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Related Party Agreements and Transactions MPC Loan Agreement (Details) - Related Party Revolving Credit Agreement [Member] - MPC Investment [Member] - USD ($) $ in Millions				6 Months Ended	12 Months Ended
		Jul. 31, 2019	Apr. 27, 2018	Jun. 30, 2020	Dec. 31, 2019	Dec. 21, 2018
Related Party Transaction [Line Items]
Line of Credit Facility, Current Borrowing Capacity		$ 1,500
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 1.25 percent	LIBOR plus 1.50 percent
Proceeds from Lines of Credit				$ 2,708	$ 8,540
Line of Credit Facility, Interest Rate During Period				2.733%	3.441%
Repayments of Lines of Credit				$ 3,302	$ 7,946
Long-term Line of Credit	[1]			$ 0	594
ANDX LP [Member]
Related Party Transaction [Line Items]
Line of Credit Facility, Current Borrowing Capacity						$ 500
Proceeds from Lines of Credit					$ 773
Line of Credit Facility, Interest Rate During Period					4.249%
Repayments of Lines of Credit					$ 773
Long-term Line of Credit	[1]				$ 0

[1] Included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

XML

Sales to Related Parties (Detail) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Related Party Transaction [Line Items]
Rental income - related parties		$ 237	$ 286	[1]	$ 471	$ 611	[1]
Other income - related parties		63	27	[1]	127	53	[1]
MPC
Related Party Transaction [Line Items]
Rental income - related parties		237	286		471	611
Other income - related parties		48	10		96	20
Product sales to MPC that net to zero		52	295		225	518
Other Affiliates [Member]
Related Party Transaction [Line Items]
Other income - related parties		15	17		31	33
Product [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		30	36	[1],[2]	63	77	[1],[2]
Product [Member] | MPC
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	[3]	30	36		63	77
Service [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		857	847	[1],[2]	1,785	1,650	[1],[2]
Service [Member] | MPC
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		857	847		1,784	1,650
Service [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		$ 0	$ 0		$ 1	$ 0

[1] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] There were additional product sales to MPC that net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and six months ended June 30, 2020, these sales totaled $52 million and $225 million. For the three and six months ended June 30, 2019, these sales totaled $295 million and $518 million.

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Summary of Charges for Employee Services and Omnibus Agreements (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Purchases - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	$ 280	$ 313	$ 556	$ 591
MPC | Rental cost of sales - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	41	36	87	79
MPC | Purchases - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	276	308	547	581
MPC | General and administrative expenses
Related Party Transaction [Line Items]
Labor and Related Expense	68	53	132	115
Other Affiliates [Member] | Purchases - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	4	5	9	10
Construction-in-progress | MPC
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 15	$ 38	$ 51	$ 79

XML

Other Assets and Liabilities from Related Parties (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Other current assets	$ 48	$ 110
Current Assets, Related Parties	594	656
Operating Lease, Right-of-Use Asset	341	365
Other Assets, Related Parties, Noncurrent	676	303
Operating Lease, Liability, Current	69	66
Current Liabilities, Related Parties	372	1,008
Operating Lease, Liability, Noncurrent	274	302
Liabilities, Related Parties, Noncurrent	287	290
MPC
Related Party Transaction [Line Items]
Receivables - related parties	547	621
Prepaid Insurance	11	9
Other current assets	1	0
Sales-type Lease, Interest Income	28	4
Sales-type Lease, Unguaranteed Residual Asset	20	7
Due from Related Parties, Noncurrent	30	21
Operating Lease, Right-of-Use Asset	231	232
Net Investment in Lease, Noncurrent	395	43
Due to Related Parties, Current	260	911
Operating Lease, Liability, Current	1	1
Operating Lease, Liability, Noncurrent	230	230
Other Affiliates [Member]
Related Party Transaction [Line Items]
Receivables - related parties	7	22
Due to Related Parties, Current	36	37
Minimum Committed Volume Contracts [Member] | MPC
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	56	42
Reimbursable Projects [Member] | MPC
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	18	16
Deferred Revenue, Noncurrent, Related Parties	51	53
Other Noncurrent Liabilities [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	1	1
Other Noncurrent Liabilities [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Deferred Revenue, Noncurrent, Related Parties	$ 6	$ 7

XML

Net Income Per Limited Partner Unit - Schedule of Distributions by Partner by Class (Detail) - USD ($) shares in Millions		3 Months Ended							6 Months Ended
		Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2019		Mar. 31, 2019	[6]	Jun. 30, 2020		Jun. 30, 2019
Net Income Per Share [Line Items]
Potentially dilutive units					1				1		1
Net income attributable to MPLX LP		$ 648,000,000	[1]		$ 482,000,000	[2],[3]			$ (2,076,000,000)	[4]	$ 985,000,000	[2],[5]
Less: Distribution declared		746,000,000			734,000,000				1,505,000,000		1,277,000,000
Undistributed net income (loss) attributable to MPLX LP		(98,000,000)			(252,000,000)				(3,581,000,000)		(292,000,000)
Undistributed net loss attributable to MPLX LP		(98,000,000)			(252,000,000)				(3,581,000,000)		(292,000,000)
Capital Contribution By Related Party		6,000,000		$ 225,000,000	13,000,000		$ 15,000,000
Limited Partners Common Units
Net Income Per Share [Line Items]
Net income attributable to MPLX LP		617,000,000	[1]		440,000,000	[3]			(2,138,000,000)	[4]	923,000,000	[5]
Less: Distribution declared	[7]	715,000,000			692,000,000	[8]			1,443,000,000		1,215,000,000	[8]
Undistributed net income (loss) attributable to MPLX LP		(98,000,000)			(252,000,000)				(3,581,000,000)		(292,000,000)
MPC | Limited Partners Common Units
Net Income Per Share [Line Items]
Capital Contribution By Related Party		6,000,000		$ 225,000,000	0	[6]	$ 0
MPC | ANDX LP [Member]
Net Income Per Share [Line Items]
Capital Contribution By Related Party					12,500,000						12,500,000
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP		21,000,000	[1]		21,000,000	[3]			41,000,000	[4]	41,000,000	[5]
Less: Distribution declared	[7]	21,000,000			21,000,000				41,000,000		41,000,000
Undistributed net income (loss) attributable to MPLX LP		0			0				0		0
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP		10,000,000	[1]		21,000,000	[3]			21,000,000	[4]	21,000,000	[5]
Less: Distribution declared	[7]	10,000,000			21,000,000				21,000,000		21,000,000
Undistributed net income (loss) attributable to MPLX LP		$ 0			$ 0				$ 0		$ 0

[1] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[4] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[5] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[6] Financial information for the first and second quarters of 2019 has been retrospectively adjusted for the acquisition of ANDX.

[7] See Note 7 for distribution information.

[8] The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

XML

Net Income Per Limited Partner Unit - Basic and Diluted Earnings Per Unit (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Potentially dilutive units				1		1		1
Distribution Made to Limited Partner, Cash Distributions Declared		$ 746		$ 734		$ 1,505		$ 1,277
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		(98)		(252)		(3,581)		(292)
Net income attributable to MPLX LP		648	[1]	482	[2],[3]	(2,076)	[4]	985	[2],[5]
Limited Partners Common Units
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[6]	715		692	[7]	1,443		1,215	[7]
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		(98)		(252)		(3,581)		(292)
Net income attributable to MPLX LP		$ 617	[1]	$ 440	[3]	$ (2,138)	[4]	$ 923	[5]
Weighted average units outstanding:
Common - basic (in shares)		1,059		794	[2],[8]	1,059		794	[2],[9]
Common - diluted (in shares)		1,059		795	[2],[8]	1,059		795	[2],[9]
Net income attributable to MPLX LP per limited partner unit:
Basic (in USD per unit)		$ 0.58		$ 0.56	[2]	$ (2.02)		$ 1.16	[2]
Diluted (in USD per unit)		$ 0.58		$ 0.55	[2]	$ (2.02)		$ 1.16	[2]
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[6]	$ 21		$ 21		$ 41		$ 41
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		0		0		0		0
Net income attributable to MPLX LP		21	[1]	21	[3]	41	[4]	41	[5]
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[6]	10		21		21		21
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		0		0		0		0
Net income attributable to MPLX LP		$ 10	[1]	$ 21	[3]	$ 21	[4]	$ 21	[5]

[1] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[4] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[5] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

[6] See Note 7 for distribution information.

[7] The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

[8] The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the three months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

[9] The Series B preferred units and the MPLX common units issued in connection with the Merger were not outstanding during the six months ended June 30, 2019. See Notes 3 and 7 for additional information about the treatment of these units.

XML

Equity - Changes in Partners Capital, Unit Rollforward (Details) - USD ($)						3 Months Ended						6 Months Ended			12 Months Ended
		Aug. 17, 2020	Jul. 28, 2020	Jul. 30, 2019	Jul. 29, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019		Mar. 31, 2019	[1]	Jun. 30, 2020	Jun. 30, 2019		Dec. 31, 2019	Dec. 31, 2018
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity						$ (634,000,000)	$ 2,736,000,000	$ (636,000,000)		$ (669,000,000)
Partners, Total Subsequent Distribution Amount						746,000,000		734,000,000				$ 1,505,000,000	$ 1,277,000,000
Contributions from:						6,000,000	225,000,000	13,000,000		15,000,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						(728,000,000)	(738,000,000)	(764,000,000)		(776,000,000)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest						13,262,000,000	13,356,000,000	17,611,000,000		17,730,000,000		13,262,000,000	17,611,000,000		$ 16,613,000,000	$ 17,731,000,000
Distribution Made to Limited Partner, Cash Distributions Declared						746,000,000		734,000,000				1,505,000,000	1,277,000,000
Preferred Class B [Member]
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity						(10,000,000)	(11,000,000)	0	[1]	0
Contributions from:						0	0	0	[1]	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						0	(21,000,000)	0	[1]	0		(21,000,000)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest						$ 611,000,000	$ 601,000,000	0		0		$ 611,000,000	0		$ 611,000,000	0
Limited Partners Common Units
Stockholders Equity [Line Items]
Balance at December 31, 2019							1,058,355,471					1,058,355,471
Unit-based compensation awards												253,291
Balance at June 30, 2020						1,058,608,762						1,058,608,762			1,058,355,471
Distribution Made to Limited Partner, Cash Distributions Declared	[2]					$ 715,000,000		692,000,000	[3]			$ 1,443,000,000	1,215,000,000	[3]
Andeavor Logistics [Member]
Stockholders Equity [Line Items]
Preferred Units, Outstanding					600,000
ANDX LP [Member]
Stockholders Equity [Line Items]
Dividend rate, percentage					6.875%
Price per share					$ 1,000
Subsequent Event | Limited Partners Common Units
Stockholders Equity [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared			$ 715,000,000
Series B Preferred Stock [Member] | Preferred Partner [Member]
Stockholders Equity [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[2]					10,000,000		21,000,000				$ 21,000,000	21,000,000
Series B Preferred Stock [Member] | MPLX LP
Stockholders Equity [Line Items]
Dividend rate, percentage												4.652%
Preferred Stock, Dividend Payment Rate, Variable												LIBOR plus
Preferred Class B [Member]
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity												$ (21,000,000)
Partners, Total Subsequent Distribution Amount						10,000,000		21,000,000				$ 21,000,000	21,000,000
Preferred Class B [Member] | Subsequent Event
Stockholders Equity [Line Items]
Partners, Total Subsequent Distribution Amount		$ 21,000,000
MPC | Limited Partners Common Units
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity						$ 388,000,000	$ (1,733,000,000)	293,000,000		307,000,000
Units issued				161,000,000		666,000,000						666,000,000			666,000,000
Contributions from:						$ 6,000,000	225,000,000	0	[1]	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						(458,000,000)	(446,000,000)	(332,000,000)		(327,000,000)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest						$ 2,951,000,000	3,014,000,000	(1,671,000,000)		(1,632,000,000)		$ 2,951,000,000	(1,671,000,000)		$ 4,968,000,000	(1,612,000,000)
Units Outstanding						666,000,000						666,000,000			666,000,000
MPC | ANDX LP [Member]
Stockholders Equity [Line Items]
Contributions from:								12,500,000					12,500,000
Public | Limited Partners Common Units
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity						$ 229,000,000	(1,022,000,000)	168,000,000		176,000,000
Units issued				102,000,000		393,000,000						393,000,000			392,000,000
Contributions from:						$ 0	0	0		0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						(270,000,000)	(271,000,000)	(191,000,000)		(188,000,000)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest						$ 9,469,000,000	$ 9,509,000,000	$ 8,305,000,000		$ 8,326,000,000		$ 9,469,000,000	$ 8,305,000,000		$ 10,800,000,000	$ 8,336,000,000
Units Outstanding						393,000,000						393,000,000			392,000,000
Nonpublic [Member] | ANDX LP [Member]
Stockholders Equity [Line Items]
Common Units Conversion Ratio - ANDX to MPLX				1.0328
Public | ANDX LP [Member]
Stockholders Equity [Line Items]
Common Units Conversion Ratio - ANDX to MPLX				1.135
TexNew Mex units [Member] | MPLX LP
Stockholders Equity [Line Items]
Units Outstanding				80,000
Distribution Made to Limited Partner, Cash Distributions Declared												$ 2,000,000			$ 1,000,000

[1] Financial information for the first and second quarters of 2019 has been retrospectively adjusted for the acquisition of ANDX.

[2] See Note 7 for distribution information.

[3] The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

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Equity - Cash Distributions (Details) - USD ($) $ / shares in Units, shares in Millions							3 Months Ended						6 Months Ended			12 Months Ended
		Aug. 17, 2020	Aug. 14, 2020	Aug. 07, 2020	Jul. 28, 2020	Jul. 29, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019		Mar. 31, 2019		Jun. 30, 2020	Jun. 30, 2019		Dec. 31, 2019	Jul. 30, 2019	Dec. 31, 2018
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Contributions from:							$ 6,000,000	$ 225,000,000	$ 13,000,000		$ 15,000,000	[1]
Distribution Made to Limited Partner, Cash Distributions Declared							746,000,000		734,000,000				$ 1,505,000,000	$ 1,277,000,000
Partners, Total Subsequent Distribution Amount							746,000,000		734,000,000				1,505,000,000	1,277,000,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							8,000,000	9,000,000	6,000,000		6,000,000	[1]
Partners' Capital Account, Distributions							728,000,000	738,000,000	764,000,000		776,000,000	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest							13,262,000,000	$ 13,356,000,000	17,611,000,000		$ 17,730,000,000	[1]	13,262,000,000	17,611,000,000		$ 16,613,000,000		$ 17,731,000,000
Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Partners, Total Subsequent Distribution Amount							715,000,000		692,000,000				1,443,000,000	1,215,000,000
Preferred Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Partners, Total Subsequent Distribution Amount							21,000,000		21,000,000				41,000,000	41,000,000
Preferred Class B [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Partners, Total Subsequent Distribution Amount							10,000,000		21,000,000				21,000,000	21,000,000
Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Declaration Date					Jul. 28, 2020
Cash distributions declared per limited partner common unit					$ 0.6875
Date of record				Aug. 07, 2020
Subsequent Event | Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution date			Aug. 14, 2020
Subsequent Event | Preferred Class B [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution date		Aug. 17, 2020
Partners, Total Subsequent Distribution Amount		$ 21,000,000
Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[2]						$ 715,000,000		$ 692,000,000	[3]			1,443,000,000	1,215,000,000	[3]
Cash distributions declared per limited partner common unit							$ 0.6875	$ 0.6875	$ 0.6675		$ 0.6575
Limited Partners Common Units | Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared					$ 715,000,000
Series A Preferred Stock [Member] | Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[2]						$ 10,000,000		$ 21,000,000				21,000,000	21,000,000
Series A Preferred Stock [Member] | Preferred Class B [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Cash distributions declared per limited partner common unit							$ 68.75
Preferred Class B [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Contributions from:							$ 0	$ 0	0	[1]	$ 0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							0	0	0	[1]	0	[1]
Partners' Capital Account, Distributions							0	21,000,000	0	[1]	0	[1]	21,000,000
Partners' Capital, Including Portion Attributable to Noncontrolling Interest							$ 611,000,000	601,000,000	0		0	[1]	$ 611,000,000	0		$ 611,000,000		0
MPC | Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Limited Partners' Capital Account, Units Issued							666						666			666	161
Contributions from:							$ 6,000,000	225,000,000	0	[1]	0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							0	0	0		0	[1]
Partners' Capital Account, Distributions							458,000,000	446,000,000	332,000,000		327,000,000	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest							$ 2,951,000,000	3,014,000,000	(1,671,000,000)		(1,632,000,000)	[1]	$ 2,951,000,000	(1,671,000,000)		$ 4,968,000,000		(1,612,000,000)
MPC | ANDX LP [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Contributions from:									12,500,000					12,500,000
ANDX LP [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Preferred Stock, Dividend Rate, Percentage						6.875%
MPLX LP | Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Preferred Stock, Dividend Payment Rate, Variable													LIBOR plus
Preferred Stock, Dividend Rate, Percentage													4.652%
TexNew Mex units [Member] | MPLX LP
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared													$ 2,000,000			$ 1,000,000
Public | Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Limited Partners' Capital Account, Units Issued							393						393			392	102
Contributions from:							$ 0	0	0		0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							0	0	0		0	[1]
Partners' Capital Account, Distributions							270,000,000	271,000,000	191,000,000		188,000,000	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest							$ 9,469,000,000	$ 9,509,000,000	$ 8,305,000,000		$ 8,326,000,000	[1]	$ 9,469,000,000	$ 8,305,000,000		$ 10,800,000,000		$ 8,336,000,000

[1] Financial information for the first and second quarters of 2019 has been retrospectively adjusted for the acquisition of ANDX.

[2] See Note 7 for distribution information.

[3] The three and six months ended June 30, 2019 amounts are net of $12.5 million of waived distributions with respect to units held by MPC and its affiliates.

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Series A Preferred Units (Narrative) (Details) - $ / shares shares in Millions	Jul. 28, 2020	May 13, 2016	Jun. 30, 2020
Series A Convertible Preferred Units
Redeemable Noncontrolling Interest [Line Items]
Issuance of preferred units		30.8
Dividend rate, percentage		6.50%
Price per share		$ 32.50
Dividend rate, per-dollar-amount		$ 0.528125
Description		The holders may convert their Series A preferred units into common units at any time, in full or in part, subject to minimum conversion amounts and conditions. After the fourth anniversary of the issuance date, MPLX may convert the Series A preferred units into common units at any time, in whole or in part, subject to certain minimum conversion amounts and conditions, if the closing price of MPLX LP common units is greater than $48.75 for the 20-day trading period immediately preceding the conversion notice date. The conversion rate for the Series A preferred units shall be the quotient of (a) the sum of (i) $32.50, plus (ii) any unpaid cash distributions on the applicable preferred unit, divided by (b) $32.50, subject to adjustment for unit distributions, unit splits and similar transactions. The holders of the Series A preferred units are entitled to vote on an as-converted basis with the common unitholders and have certain other class voting rights with respect to any amendment to the MPLX partnership agreement that would adversely affect any rights, preferences or privileges of the preferred units. In addition, upon certain events involving a change of control, the holders of preferred units may elect, among other potential elections, to convert their Series A preferred units to common units at the then change of control conversion rate.
Partners' Capital Account, Units			29.6
Subsequent Event
Redeemable Noncontrolling Interest [Line Items]
Distribution Made to Limited Partner, Declaration Date	Jul. 28, 2020
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.6875

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Series A Preferred Units (Rollforward of Redeemable Preferred Units) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	[1]
Redeemable Noncontrolling Interest [Line Items]
Balance at December 31, 2019	$ 968
Distributions to unitholders and general partner	(1,445)	$ (1,038)
Balance at June 30, 2020	968
Series A Convertible Preferred Units
Redeemable Noncontrolling Interest [Line Items]
Balance at December 31, 2019	968
Net income allocated	41
Distributions to unitholders and general partner	(41)
Balance at June 30, 2020	$ 968

[1] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Segment Information (Details)	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Number of reportable segments	2

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Segment Information - Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 321	[1]	$ 313	[1],[2],[3]	$ 646		$ 614	[2],[4]
Total revenues from contracts with customers	1,592		1,717	[5]	3,373		3,425	[5]
Rental income	98		93	[2]	194		192	[2]
Income/(loss) from equity method investments(2)	89		83	[2],[3]	(1,095)	[6],[7]	160	[2],[4]
Other income	2		4	[2]	3		4	[2]
Total segment revenues and other income	(2,081)		(2,210)	[2],[5]	(3,073)		(4,445)	[2],[5]
Investments in unconsolidated affiliates					(222)		(323)	[4]
L&S
Segment Reporting Information [Line Items]
Depreciation and amortization	138		134		276		260
Total revenues from contracts with customers	952		942	[5]	1,975		1,846	[5]
Investments in unconsolidated affiliates	(74)		(61)		(128)		(68)
G&P
Segment Reporting Information [Line Items]
Depreciation and amortization	183		179		370		354
Total revenues from contracts with customers	640		775	[5]	1,398		1,579	[5]
Investments in unconsolidated affiliates	(57)		(127)		(94)		(255)
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	1,227		920	[3]	2,521		1,850
Operating Segments | L&S
Segment Reporting Information [Line Items]
Rental income	246		296	[3]	488		631
Income/(loss) from equity method investments(2)	40		54	[3]	90		99
Other income	52		16	[3]	103		28
Total segment revenues and other income	(1,290)	[1]	(1,308)	[1],[3]	(2,656)		(2,604)
Adjusted EBITDA	839	[8]	570	[3],[8]	1,711		1,129
Capital Expenditure	108		230	[3]	292		428	[3]
Operating Segments | G&P
Segment Reporting Information [Line Items]
Rental income	89		83	[3]	177		172
Income/(loss) from equity method investments(2)	49		29	[3]	(1,185)		61
Other income	13		15	[3]	27		29
Total segment revenues and other income	(791)	[1]	(902)	[1],[3]	(417)		(1,841)
Adjusted EBITDA	388	[8]	350	[3],[8]	810		721
Capital Expenditure	110		326	[3]	244		632	[3]
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA attributable to Predecessor	0	[9]	329	[3],[9]	0		662
Service [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	563		619	[2],[5]	1,175		1,233	[2],[5]
Service [Member] | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	77		79	[5]	161		165	[5]
Service [Member] | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	486		540	[5]	1,014		1,068	[5]
Service [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	931		922	[3]	1,935		1,811
Service [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	489		544	[3]	1,025		1,072
Product [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	120		189	[2]	289		405	[2]
Product [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	21		20	[3]	40		35
Product [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers	151		231	[3]	373		507
Third Party [Member] | L&S
Segment Reporting Information [Line Items]
Total segment revenues and other income	(146)		(163)		(304)		(316)
Third Party [Member] | G&P
Segment Reporting Information [Line Items]
Total segment revenues and other income	$ (748)		$ (851)		$ (323)		$ (1,738)

[1] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[6] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[7] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

[8] See below for the reconciliation from Segment Adjusted EBITDA to net income.

[9] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Segment Information - Assets by Segment (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Segment Reporting, Other Significant Reconciling Item [Line Items]
Cash and cash equivalents	$ 67	$ 15
Assets	37,022	40,430
L&S | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Assets	21,308	20,810
G&P | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Assets	$ 15,647	$ 19,605

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Segment Information - Reconciliation to Net Income (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization	$ 321	[1]	$ 313	[1],[2],[3]	$ 646		$ 614	[2],[4]
Income Tax Expense (Benefit)	0		1	[2],[3]	0		2	[2]
Amortization of Debt Issuance Costs					(29)		(19)	[4]
Share-based Payment Arrangement, Expense	(3)		(5)	[3]	(8)		(12)
Goodwill and Intangible Asset Impairment	0		0	[2],[3]	(2,165)		0	[2],[4]
Interest and Other Financial Costs	(208)		(217)	[3]	(424)		(434)
Income/(loss) from equity method investments(2)	89		83	[2],[3]	(1,095)	[5],[6]	160	[2],[4]
Proceeds from Equity Method Investment, Distribution, Return of Capital					(226)		(245)	[4]
Acquisition Costs, Period Cost	0		(4)	[3]	0		(5)
Other Cost and Expense, Operating	1		0	[3]	2		0
Net income	655		657	[2],[3],[7]	(2,061)		1,346	[2],[4],[7]
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	1,227		920	[3]	2,521		1,850
Amortization of Debt Issuance Costs	(15)		(12)	[3]	(29)		(19)
Segment Reconciling Items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Proceeds from Equity Method Investment, Distribution, Return of Capital	(115)		(132)	[3]	(239)		(254)
Adjusted EBITDA attributable to noncontrolling interests	8		7	[3]	17		14
L&S
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization	138		134		276		260
L&S | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	839	[8]	570	[3],[8]	1,711		1,129
Income/(loss) from equity method investments(2)	40		54	[3]	90		99
G&P
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization	183		179		370		354
G&P | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	388	[8]	350	[3],[8]	810		721
Income/(loss) from equity method investments(2)	49		29	[3]	(1,185)		61
Not Designated as Hedging Instrument [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ (6)	[8]	$ 0	[3],[8]	$ 9		$ (4)

[1] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[6] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

[7] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[8] See below for the reconciliation from Segment Adjusted EBITDA to net income.

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Inventories (Summary of Inventories) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
NGLs	$ 2	$ 5
Line fill	8	10
Spare parts, materials and supplies	105	95
Total inventories	$ 115	$ 110

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Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020		Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 174
Property, plant and equipment, gross		$ 26,792		$ 26,867
Less accumulated depreciation(1)		5,034	[1]	4,722
Property, plant and equipment, net		21,758		22,145
L&S
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		12,638		12,934
L&S | Terminals
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		5,719		5,572
L&S | Marine
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		960		906
L&S | Terminals and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,281		1,109
L&S | Refineries and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		2,324		2,870
L&S | Land, building and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,834		1,817
L&S | Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		520		660
G&P
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		14,154		13,933
G&P | Pipelines
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		7,374		7,159
G&P | Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		5,923		5,545
G&P | Land, building and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		489		484
G&P | Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 368		$ 745
Maximum [Member] | L&S | Terminals
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		51 years
Maximum [Member] | L&S | Marine
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		20 years
Maximum [Member] | L&S | Terminals and related assets
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Maximum [Member] | L&S | Refineries and related assets
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Maximum [Member] | L&S | Land, building and other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		61 years
Maximum [Member] | G&P | Pipelines
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Maximum [Member] | G&P | Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Maximum [Member] | G&P | Land, building and other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Minimum [Member] | L&S | Terminals
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		2 years
Minimum [Member] | L&S | Marine
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		15 years
Minimum [Member] | L&S | Terminals and related assets
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		4 years
Minimum [Member] | L&S | Refineries and related assets
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		13 years
Minimum [Member] | L&S | Land, building and other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		1 year
Minimum [Member] | G&P | Pipelines
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		5 years
Minimum [Member] | G&P | Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		15 years
Minimum [Member] | G&P | Land, building and other
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		3 years

[1] The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020 as discussed below.

XML

Goodwill and Intangibles Goodwill (Details)		3 Months Ended	6 Months Ended	12 Months Ended
	Nov. 30, 2019	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Goodwill [Line Items]
Goodwill, Gross			$ 10,863,000,000		$ 10,146,000,000
Goodwill, Impaired, Accumulated Impairment Loss			(3,141,000,000)		(130,000,000)
Goodwill		$ 7,700,000,000	7,722,000,000	$ 9,536,000,000	10,016,000,000
Goodwill, Impairment Loss			(1,814,000,000)	(1,197,000,000)
Goodwill, Acquired During Period				717,000,000
Total Number of Reporting Units		6
Reporting Unit, Zero or Negative Carrying Amount, Amount of Allocated Goodwill				1
Number of Reporting Units	6	4
Crude Gathering [Member]
Goodwill [Line Items]
Goodwill		$ 1,100,000,000
Minimum [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		8.50%
Maximum [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		270.00%
L&S
Goodwill [Line Items]
Goodwill, Gross			7,722,000,000		7,234,000,000
Goodwill, Impaired, Accumulated Impairment Loss			0		0
Goodwill			7,722,000,000	7,722,000,000	7,234,000,000
Goodwill, Impairment Loss			0	0
Goodwill, Acquired During Period				488,000,000
G&P
Goodwill [Line Items]
Goodwill, Gross			3,141,000,000		2,912,000,000
Goodwill, Impaired, Accumulated Impairment Loss			(3,141,000,000)		(130,000,000)
Goodwill			0	1,814,000,000	$ 2,782,000,000
Goodwill, Impairment Loss		$ (1,814,000,000)	$ (1,814,000,000)	(1,197,000,000)
Goodwill, Acquired During Period				$ 229,000,000
Valuation, Income Approach [Member] | Measurement Input, Discount Rate [Member] | Goodwill [Member] | Minimum [Member]
Goodwill [Line Items]
Fair Value Inputs		9.50%
Valuation, Income Approach [Member] | Measurement Input, Discount Rate [Member] | Goodwill [Member] | Maximum [Member]
Goodwill [Line Items]
Fair Value Inputs		11.50%

XML

Goodwill and Intangibles Intangibles (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Mar. 31, 2020	Jun. 30, 2020		Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived		$ 177
Finite-Lived Intangible Assets, Gross			$ 1,571		$ 1,571
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months			64
Finite-Lived Intangible Asset, Expected Amortization, Year Two			128
Finite-Lived Intangible Asset, Expected Amortization, Year Three			128
Finite-Lived Intangible Asset, Expected Amortization, Year Four			128
Finite-Lived Intangible Asset, Expected Amortization, Year Five			124
Finite-Lived Intangible Asset, Expected Amortization, after Year Five			451
Finite-Lived Intangible Assets, Net			1,023
Finite-Lived Intangible Assets, Accumulated Amortization	[1]		(548)		(301)
Intangibles, net			1,023		1,270
L&S
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets			18
Finite-Lived Intangible Assets, Gross			283		283
Finite-Lived Intangible Assets, Accumulated Amortization	[1]		(63)		(45)
Intangibles, net			$ 220		238
L&S | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			6 years
L&S | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			8 years
G&P
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets			$ 52
Finite-Lived Intangible Assets, Gross			1,288		1,288
Finite-Lived Intangible Assets, Accumulated Amortization	[1]		(485)	[2]	(256)
Intangibles, net			$ 803		$ 1,032
G&P | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			6 years
G&P | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			25 years

[1] Amortization expense attributable to the G&P and L&S segments for the six months ended June 30, 2020 was $52 million and $18 million, respectively.

[2] Impairment charge of $177 million is included within the G&P accumulated amortization.

XML

Fair Value Measurements - Recurring - Financial Instruments by Valuation Hierarchy (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 0	$ 0
Derivative liability	51	60
Embedded derivatives in commodity contracts | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	0	0
Derivative liability	$ 51	$ 60

XML

Fair Value Measurments - Recurring - Significant Unobservable Inputs in Level 3 Valuation (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.53
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Embedded Derivative Renewal Term	5 years
Embedded Derivative Second Renewal Term	5 years
Fair Value, Inputs, Level 3 [Member] | Embedded derivatives in commodity contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Probability of Renewal Second Term	100.00%
Fair Value Inputs Probability of Renewal	100.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Commodity contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Forward Commodity Price	$ 0.38
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Commodity contracts
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Forward Commodity Price	$ 0.92

XML

Fair Value Measurements - Recurring - Changes in Level 3 Measurements (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Commodity Derivative Contracts (net)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value at beginning of period		$ 0	$ 0	$ 0	$ 0
Total gains (losses) (realized and unrealized) included in earnings	[1]	0	0	0	0
Settlements		0	0	0	0
Fair value at end of period		0	0	0	0
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized losses relating to liabilities still held at end of period		0	0	0	0
Embedded Derivatives in Commodity Contracts (net)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value at beginning of period		(45)	(65)	(60)	(61)
Total gains (losses) (realized and unrealized) included in earnings	[1]	(7)	(1)	7	(7)
Settlements		1	1	2	3
Fair value at end of period		(51)	(65)	(51)	(65)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized losses relating to liabilities still held at end of period		$ (6)	$ (2)	$ 7	$ (5)

[1] Gains and losses on commodity derivative contracts classified as Level 3 are recorded in “Product sales” on the Consolidated Statements of Income. Gains and losses on derivatives embedded in commodity contracts are recorded in “Purchased product costs” and “Cost of revenues” on the Consolidated Statements of Income.

XML

Fair Value Measurements - Reported (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 20,646	$ 19,800
SMR liability	78	80
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	21,919	21,054
SMR liability	$ 88	$ 90

XML

Derivative Financial Instruments - Embedded Derivatives in Commodity Contracts (Details) - Natural Gas [Member] - Embedded derivatives in commodity contracts $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Derivative [Line Items]
Number of Renewals	2
Embedded Derivative Renewal Term	5 years
Embedded Derivative Fair Value of Embedded Derivative Liability Including Inception Value Allocable to Host Contract	$ 51	$ 60

XML

Derivative Financial Instruments - Derivatives Balance Sheet Location (Details) - Not Designated as Hedging Instrument [Member] - Commodity contracts - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	[1]	51	60
Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	0	0
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	[1]	3	5
Other noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	0	0
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	[1]	$ 48	$ 55

[1] Includes embedded derivatives in commodity contracts as discussed above.

XML

Derivatives Financial Instruments - Derivative Income Statement Location (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Total gain (loss)	$ (7)		$ (1)		$ 7	$ (7)
Purchased product costs
Derivative [Line Items]
Realized gain (loss)	(1)		(1)		(2)	(3)
Total gain (loss)	(7)		(1)		7	(7)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(6)	[1]	0	[1],[2]	9	(4)
Not Designated as Hedging Instrument [Member] | Purchased product costs
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ (6)		$ 0		$ 9	$ (4)

[1] See below for the reconciliation from Segment Adjusted EBITDA to net income.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Debt - Summary of Outstanding Borrowings (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019	Sep. 09, 2019
Debt Instrument [Line Items]
Total		$ 20,938	$ 20,119
Unamortized debt issuance costs		(100)	(106)
Unamortized discount/premium		(279)	(300)
Amounts due within one year		(3)	(9)
Total long-term debt due after one year		20,556	19,704
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross				$ 2,000
Senior Notes [Member] | MarkWest [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		23	23
Senior Notes [Member] | ANDX LP [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		190	190
Variable Rate Senior Notes [Member] | MPLX LP
Debt Instrument [Line Items]
Long-term Debt, Gross		2,000	2,000
Fixed Rate Senior Notes [Member] | MPLX LP
Debt Instrument [Line Items]
Long-term Debt, Gross		16,887	16,887
Finance Lease [Member] | Marathon Pipe Line LLC [Member]
Debt Instrument [Line Items]
Financing lease obligations(1)	[1]	13	19
Floating Rate Senior Notes Due September 2021 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross				1,000
Floating Rate Senior Notes Due September 2022 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross				$ 1,000
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Long-term Line of Credit		825	0
MPLX Term Loan [Member]
Debt Instrument [Line Items]
Long-term Line of Credit		$ 1,000	$ 1,000
Minimum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.375%
Maximum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.375%

[1] See Note 20 for lease information.

XML

Debt Debt - Summary of Outstanding Borrowings - Interest Rates and Table Due Dates (Details)	6 Months Ended
	Jun. 30, 2020
MPLX LP | Line of Credit [Member] | MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Expiration Date	Jul. 30, 2024
MPLX LP | Senior Notes [Member] | Floating Rate Senior Notes Due September 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Sep. 09, 2021
MPLX LP | Senior Notes [Member] | Floating Rate Senior Notes Due September 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Sep. 09, 2022
Minimum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.375%
Minimum [Member] | MPLX LP | Senior Notes [Member] | Senior Notes Due October 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Oct. 15, 2022
Maximum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.375%
Maximum [Member] | MPLX LP | Senior Notes [Member] | Senior Notes Due April 2058 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Apr. 15, 2058

XML

Debt - Additional Information (Detail) - USD ($) $ in Millions			6 Months Ended
	Sep. 26, 2019	Sep. 09, 2019	Jun. 30, 2020	Jun. 30, 2019	[1]	Dec. 31, 2019	Jul. 30, 2019
Debt Instrument [Line Items]
Repayments of Long-term Debt			$ 1,682	$ 2,272
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity							$ 3,500
Long-term Line of Credit			825			$ 0
MPLX Revolving Credit Facility due July 2024 [Member] | MPLX LP
Debt Instrument [Line Items]
Proceeds from Lines of Credit			$ 2,500
Debt Instrument, Interest Rate, Effective Percentage			1.525%
Repayments of Long-term Lines of Credit			$ 1,675
Letters of Credit Outstanding			1
Line of Credit Facility, Remaining Borrowing Capacity			$ 2,675
Line of Credit Facility, Remaining Borrowing Capacity, Percentage			76.40%
MPLX Term Loan [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000
Debt Instrument, Description of Variable Rate Basis	(i) the Adjusted LIBO Rate (as defined in the Term Loan Agreement) plus a margin ranging from 75.0 basis points to 100.0 basis points per annum, depending on MPLX’s credit ratings, or (ii) the Alternate Base Rate (as defined in the Term Loan Agreement).
Long-term Debt, Maturity Date			Sep. 26, 2021
Long-term Line of Credit			$ 1,000			1,000
MPLX Term Loan [Member] | MPLX LP
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage			1.665%
Senior Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 2,000
Percent of Par		100.00%
Senior Notes [Member] | ANDX LP [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 190			190
Senior Notes [Member] | MarkWest [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 23			$ 23
Senior Notes [Member] | Floating Rate Senior Notes Due September 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,000
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 0.9 percent per annum
Senior Notes [Member] | Floating Rate Senior Notes Due September 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,000
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 1.1 percent per annum
Minimum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			3.375%
Maximum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.375%

[1] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,592	$ 1,717	[1]	$ 3,373		$ 3,425	[1]
Rental income		98	93	[2]	194		192	[2]
Rental income - related parties		237	286	[2]	471		611	[2]
Income/(loss) from equity method investments(2)		89	83	[2],[3]	(1,095)	[4],[5]	160	[2],[6]
Other income		2	4	[2]	3		4	[2]
Other income - related parties		63	27	[2]	127		53	[2]
Operating Income (Loss)	[7]	489	493	[1]	(300)		1,020	[1]
Total segment revenues and other income		2,081	2,210	[1],[2]	3,073		4,445	[1],[2]
L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		952	942	[1]	1,975		1,846	[1]
G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		640	775	[1]	1,398		1,579	[1]
Service [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		563	619	[1],[2]	1,175		1,233	[1],[2]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		857	847	[1],[2]	1,785		1,650	[1],[2]
Service [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		77	79	[1]	161		165	[1]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		854	843	[1]	1,774		1,646	[1]
Service [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		486	540	[1]	1,014		1,068	[1]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		3	4	[1]	11		4	[1]
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		22	26	[1],[2]	61		60	[1],[2]
Service, Other [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	[1]	0		0	[1]
Service, Other [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		22	26	[1]	61		60	[1]
Product [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		120	189	[2]	289		405	[2]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		30	36	[1],[2]	63		77	[1],[2]
Revenue from Contract with Customer, excluding Assessed Tax and Non-ASC 606 Revenue		120	189	[1]	289		405	[1]
Product [Member] | L&S
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		4	5	[1]	8		9	[1]
Revenue from Contract with Customer, excluding Assessed Tax and Non-ASC 606 Revenue		17	15	[1]	32		26	[1]
Product [Member] | G&P
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		26	31	[1]	55		68	[1]
Revenue from Contract with Customer, excluding Assessed Tax and Non-ASC 606 Revenue		$ 103	$ 174	[1]	$ 257		$ 379	[1]

[1] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[5] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

[6] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[7] Non-ASC 606 Revenue includes rental income, income/(loss) from equity method investments, derivative gains and losses, mark-to-market adjustments, and other income.

XML

Revenue Contract Balances (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Long-term deferred revenue, beginning balance		$ 217
Long-term deferred revenue, ending balance		261
Liability, change in timeframe, performance obligation satisfied, revenue recognized		0	$ 0
ASC 606
Contract assets, beginning balance	[1]	39	36
Contract assets, additions/(deletions)		(20)	(8)	[2]
Contract assets, revenue recognized	[3]	(1)	(1)	[2]
Contract assets, ending balance		18	27	[2]
Deferred revenue, beginning balance	[1]	23	13
Deferred revenue, additions/(deletions)		8	4	[2]
Deferred revenue, revenue recognized	[3]	(5)	(3)	[2]
Deferred revenue, ending balance		26	14	[2]
Deferred revenue - related parties, beginning balance	[1]	53	65
Deferred revenue - related party, additions/(deletions)		48	18	[2]
Deferred revenue - related parties, revenue recognized	[3]	(29)	(30)	[2]
Deferred revenue - related parties, ending balance		72	53	[2]
Long-term deferred revenue, beginning balance	[1]	90	56
Long-term deferred revenue, additions/(deletions)		11	14	[2]
Long-term deferred revenue, revenue recognized	[3]	0	0	[2]
Long-term deferred revenue, ending balance		101	70	[2]
Long-term deferred revenue - related parties, beginning balance	[1]	55	52
Long-term deferred revenue - related party, additions/(deletions)		(2)	(2)	[2]
Long-term deferred revenue - related parties, revenue recognized	[3]	0	0	[2]
Long-term deferred revenue - related parties, ending balance		$ 53	$ 50	[2]

[1] Balance represents ASC 606 portion of each respective line item.

[2] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] No significant revenue was recognized related to past performance obligations in the current periods.

XML

Revenue Remaining Performance Obligations (Details) $ in Millions	Jun. 30, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Contract with customer, liability	$ 250
Revenue, Remaining Performance Obligation, Amount	12,075	[1],[2],[3]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 938
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,790
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,759
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,673
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	3 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 5,915
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	31 years

[1] All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

[2] Arrangements deemed implicit leases are included in “Rental income” and are excluded from this table.

[3] Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

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Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 423	$ 402
Income Taxes Paid, Net	1	0
Non-cash investing and financing activities:
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	$ (1)	$ 1

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Supplemental Cash Flow Information - Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Supplemental Cash Flow Elements [Abstract]
(Decrease)/increase in capital accruals	$ (172)	$ (77)

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Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	$ (16)	$ (15)	$ (15)	$ (16)
Other Comprehensive Income (Loss), Net of Tax	[2]	(1)	1
Pension Plan [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	(14)	(14)	(14)	(14)
Other Comprehensive Income (Loss), Net of Tax	[2]	0	0
Other Postretirement Benefits Plan [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	(2)	(1)	$ (1)	$ (2)
Other Comprehensive Income (Loss), Net of Tax	[2]	$ (1)	$ 1

[1] These components of “Accumulated other comprehensive loss” are included in the computation of net periodic benefit cost by LOOP and Explorer and are therefore included on the Consolidated Statements of Income under the caption “Income/(loss) from equity method investments.”

[2] Components of other comprehensive income/loss - remeasurements relate to actuarial gains and losses as well as amortization of prior service costs. MPLX records an adjustment to “Comprehensive income” in accordance with its ownership interest in LOOP and Explorer.

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Equity-Based Compensation Plan - Summary of Phantom Unit Award Activity (Details) - $ / shares		6 Months Ended
	Jul. 30, 2019	Jun. 30, 2020
Phantom Units
Number of Units
Outstanding at December 31, 2019		1,109,568
Granted		195,461
Settled		323,884
Forfeited		4,627
Outstanding at June 30, 2020		976,518
Weighted Average Fair Value
Outstanding at December 31, 2019		$ 35.97
Granted		19.43
Settled		35.67
Forfeited		36.40
Outstanding at June 30, 2020		$ 32.76
ANDX LP [Member] | Public
Equity Transactions And Share Based Compensation [Line Items]
Common Units Conversion Ratio - ANDX to MPLX	1.135

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Equity-Based Compensation Plan - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2020 $ / shares
Officer | Performance Shares [Member] | MPLX LP 2012 Incentive Compensation Plan [Member]
Equity Transactions And Share Based Compensation [Line Items]
Percentage paid out in cash	75.00%
Share Based Compensation Arrangement By Share Based Payment Award Percentage Paid Out In Stock	25.00%
2020 [Member] | Performance Units Market Condition [Member]
Equity Transactions And Share Based Compensation [Line Items]
Performance units grant date fair value (in USD per unit)	$ 0.80
2018 [Member] | Performance Units Market Condition [Member]
Equity Transactions And Share Based Compensation [Line Items]
Performance units grant date fair value (in USD per unit)	0.45
Maximum [Member] | 2020 [Member] | Performance Unit Performance Condition [Member]
Equity Transactions And Share Based Compensation [Line Items]
Performance units grant date fair value (in USD per unit)	2.00
Maximum [Member] | 2018 [Member] | Performance Unit Performance Condition [Member]
Equity Transactions And Share Based Compensation [Line Items]
Performance units grant date fair value (in USD per unit)	$ 2.00

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Equity-Based Compensation Plan - Summary of Performance Unit Award Activity (Detail) - Performance Shares [Member]	6 Months Ended
	Jun. 30, 2020 shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	1,169,354
Forfeited	(31,668)
Outstanding at June 30, 2020	3,103,536

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Leases Leases Narrative (Details) - USD ($) $ in Millions	3 Months Ended					6 Months Ended
	Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2019	[1],[2]	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Lessor, Sales-type Lease, Assumptions and Judgments, Value of Underlying Asset, Amount			$ 171
Sales-type Lease, Lease Receivable			370
Sales-type Lease, Selling Profit (Loss)			209
MPC
Operating Lease, Lease Income	$ 195	[1]		$ 246		$ 381	$ 525
Sales-type Lease, Lease Receivable	423					423
Sales-type Lease, Unguaranteed Residual Asset	20					20		$ 7
Refining Logistics [Member] | MPC
Sales-type Lease, Unguaranteed Residual Asset			$ 10
Third Party [Member]
Operating Lease, Lease Income	66	[1]		$ 68		129	$ 133
Sales-type Lease, Lease Receivable	1					1
Sales-type Lease, Selling Profit (Loss)	$ 0					$ 0

[1] These amounts are presented net of executory costs.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Leases Lessor Maturity Table (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable		$ 370
MPC
Lessor, Lease, Description [Line Items]
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Current Year	$ 78
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	157
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	157
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three	158
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four	158
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five	473
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	1,181
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount	758
Sales-type Lease, Lease Receivable	423
Third Party [Member]
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable	$ 1

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Leases Lessor Lease Revenues (Details) - USD ($) $ in Millions	3 Months Ended					6 Months Ended
	Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2019	[1],[2]	Jun. 30, 2020	Jun. 30, 2019
Lessor, Lease, Description [Line Items]
Sales-type Lease, Selling Profit (Loss)			$ 209
MPC
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 195	[1]		$ 246		$ 381	$ 525
Sales-type Lease, Interest Income	38					76
Sales-type Lease, Variable Lease Income	0					0
Third Party [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	66	[1]		$ 68		129	$ 133
Sales-type Lease, Selling Profit (Loss)	0					0
Sales-type Lease, Interest Income	0					0
Sales-type Lease, Variable Lease Income	0					0
MPC
Lessor, Lease, Description [Line Items]
Sales-type Lease, Selling Profit (Loss)	$ 0					$ 0

[1] These amounts are presented net of executory costs.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Accrued liabilities for environmental remediation	$ 18	$ 19
Loss Contingency, Damages Sought, Value	187
Contractual commitments to acquire property, plant and equipment	293
MPC
Commitments And Contingencies [Line Items]
Due to Related Parties, Current	260	911
Environmental Loss Contingency [Member] | MPC
Commitments And Contingencies [Line Items]
Due to Related Parties, Current	$ 0	$ 0
Whistler Pipeline LLC [Member]
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage	38.00%
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage	9.19%
Guarantee Type, Other [Member]
Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 230

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Subsequent Events Subsequent Events (Details) - Subsequent Event $ in Millions	Jul. 31, 2020 USD ($) shares
Subsequent Event [Line Items]
Partners' Capital Account, Units, Redeemed | shares	18,582,088
Partners' Capital Account, Redemptions | $	$ 340