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 March 31, 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 1,058,603,592 common units outstanding at May 1, 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	35
Item 3.   Quantitative and Qualitative Disclosures about Market Risk	56
Item 4.   Controls and Procedures	57
PART II – OTHER INFORMATION
Item 1.    Legal Proceedings	58
Item 1A. Risk Factors	58
Item 6.    Exhibits	59
Signatures	61

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   March 31,
(In millions, except per unit data)	2020			2019(1)
Revenues and other income:
Service revenue	$	612		$	614
Service revenue - related parties	928			803
Service revenue - product related	39			34
Rental income	96			99
Rental income - related parties	234			325
Product sales	169			216
Product sales - related parties	33			41
Income/(loss) from equity method investments(2)	(1,184		)	77
Other income	1			—
Other income - related parties	64			26
Total revenues and other income	992			2,235
Costs and expenses:
Cost of revenues (excludes items below)	368			339
Purchased product costs	135			194
Rental cost of sales	35			37
Rental cost of sales - related parties	46			43
Purchases - related parties	276			278
Depreciation and amortization	325			301
Impairment expense	2,165			—
General and administrative expenses	97			101
Other taxes	31			30
Total costs and expenses	3,478			1,323
Income/(loss) from operations	(2,486		)	912
Related party interest and other financial costs	3			1
Interest expense (net of amounts capitalized of $13 million and $11 million, respectively)	211			214
Other financial costs	16			9
Income/(loss) before income taxes	(2,716		)	688
(Benefit)/provision for income taxes	—			(1		)
Net income/(loss)	(2,716		)	689
Less: Net income attributable to noncontrolling interests	8			6
Less: Net income attributable to Predecessor	—			180
Net income/(loss) attributable to MPLX LP	(2,724		)	503
Less: Series A preferred unit distributions	20			20
Less: Series B preferred unit distributions	11			—
Limited partners’ interest in net income/(loss) attributable to MPLX LP	$	(2,755	)	$	483
Per Unit Data (See Note 6)
Net income/(loss) attributable to MPLX LP per limited partner unit:
Common - basic	$	(2.60	)	$	0.61
Common - diluted	$	(2.60	)	$	0.61
Weighted average limited partner units outstanding:
Common - basic	1,058			794
Common - diluted	1,058			795

(1) Financial information for the first quarter of 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.

3

MPLX LP

Consolidated Statements of Comprehensive Income (Unaudited)

	Three Months Ended   March 31,
(In millions)	2020			2019(1)
Net income/(loss)	$	(2,716	)	$	689
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)	(2,717		)	690
Less comprehensive income attributable to:
Noncontrolling interests	8			6
Income attributable to Predecessor	—			180
Comprehensive income/(loss) attributable to MPLX LP	$	(2,725	)	$	504

(1) Financial information for the first quarter 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.

4

MPLX LP

Consolidated Balance Sheets (Unaudited)

 

(In millions)	March 31, 2020			December 31, 2019
Assets
Current assets:
Cash and cash equivalents	$	57		$	15
Receivables, net	522			593
Current assets - related parties	600			656
Inventories	105			110
Other current assets	45			110
Total current assets	1,329			1,484
Equity method investments	3,992			5,275
Property, plant and equipment, net	21,829			22,145
Intangibles, net	1,055			1,270
Goodwill	7,722			9,536
Right of use assets, net	352			365
Noncurrent assets - related parties	677			303
Other noncurrent assets	50			52
Total assets	37,006			40,430
Liabilities
Current liabilities:
Accounts payable	138			242
Accrued liabilities	135			187
Current liabilities - related parties	297			1,008
Accrued property, plant and equipment	234			283
Accrued interest payable	214			210
Operating lease liabilities	67			66
Other current liabilities	129			136
Total current liabilities	1,214			2,132
Long-term deferred revenue	241			217
Long-term liabilities - related parties	290			290
Long-term debt	20,467			19,704
Deferred income taxes	11			12
Long-term operating lease liabilities	284			302
Deferred credits and other liabilities	175			192
Total liabilities	22,682			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)	9,509			10,800
Common unitholder - MPC (666 million and 666 million units issued and outstanding)	3,014			4,968
Series B preferred units (.6 million and .6 million units issued and outstanding)	601			611
Accumulated other comprehensive loss	(16		)	(15		)
Total MPLX LP partners’ capital	13,108			16,364
Noncontrolling interests	248			249
Total equity	13,356			16,613
Total liabilities, preferred units and equity	$	37,006		$	40,430

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

5

MPLX LP

Consolidated Statements of Cash Flows (Unaudited)

	Three Months Ended   March 31,
(In millions)	2020			2019(1)
Increase/(decrease) in cash, cash equivalents and restricted cash
Operating activities:
Net income/(loss)	$	(2,716	)	$	689
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Amortization of deferred financing costs	14			7
Depreciation and amortization	325			301
Impairment expense	2,165			—
Deferred income taxes	—			(2		)
(Gain)/loss on disposal of assets	—			1
Loss/(income) from equity method investments(2)	1,184			(77		)
Distributions from unconsolidated affiliates	119			115
Changes in:
Current receivables	71			6
Inventories	3			4
Fair value of derivatives	(15		)	7
Current accounts payable and accrued liabilities	(142		)	(69		)
Current assets/current liabilities - related parties	(52		)	(157		)
Right of use assets/operating lease liabilities	(4		)	—
Deferred revenue	27			13
All other, net	30			15
Net cash provided by operating activities	1,009			853
Investing activities:
Additions to property, plant and equipment	(379		)	(575		)
Acquisitions, net of cash acquired	—			1
Disposal of assets	39			7
Investments in unconsolidated affiliates	(91		)	(135		)
Distributions from unconsolidated affiliates - return of capital	69			2
Net cash used in investing activities	(362		)	(700		)
Financing activities:
Long-term debt - borrowings	1,325			1,404
- repayments	(581		)	(821		)
Related party debt - borrowings	1,667			1,405
- repayments	(2,261		)	(1,405		)
Distributions to noncontrolling interests	(9		)	(6		)
Distributions to Series A preferred unitholders	(20		)	(20		)
Distributions to Series B preferred unitholders	(21		)	—
Distributions to unitholders and general partner	(717		)	(515		)
Distributions to common and Series B preferred unitholders from Predecessor	—			(259		)
Contributions from MPC	14			12
Contributions from noncontrolling interests	—			94
All other, net	(2		)	(5		)
Net cash used in financing activities	(605		)	(116		)
Net (decrease)/increase in cash, cash equivalents and restricted cash	42			37
Cash, cash equivalents and restricted cash at beginning of period	15			85
Cash, cash equivalents and restricted cash at end of period	$	57		$	122

(1) Financial information for the first quarter of 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 Series A 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
Balance at December 31, 2019	10,800			4,968			611			(15		)	249			—			16,613
Net income (excludes amounts attributable to Series A 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

(1) Financial information for the first quarter 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 recent 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 the midstream services we provide. 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 our 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 have continued to refine and update production forecasts in response to the current environment, which has 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.

(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 months ended March 31, 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 March 31, 2020, we reported $522 million of accounts receivable, net of allowances of $1 million.

We are also exposed to credit losses from off-balance sheet exposures, such as guarantees of joint venture debt. See Note 21 for more information on these off-balance sheet exposures.

We also adopted the following ASU during the first three 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

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. (“Southwest, Inc.”), 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 $1 million in acquisition costs during the first quarter of 2019 related to the Merger, which are reflected in general and administrative expenses. For the three months ended March 31, 2019, we recognized $589 million of revenues and other income and $180 million of net income related to ANDX.

10

4. Investments and Noncontrolling Interests

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

	Ownership as of	Carrying value at
	March 31,	March 31,		December 31,
(In millions, except ownership percentages)	2020	2020		2019
L&S
MarEn Bakken Company LLC	25%	$	479	$	481
Illinois Extension Pipeline Company, L.L.C.	35%	271		265
LOOP LLC	41%	239		238
Andeavor Logistics Rio Pipeline LLC(1)	67%	200		202
Minnesota Pipe Line Company, LLC	17%	190		190
Whistler Pipeline LLC(1)	38%	163		134
W2W Holdings LLC(1)(2)	50%	76		—
Wink to Webster Pipeline LLC(1)(2)	15%	—		126
Explorer Pipeline Company	25%	81		83
Other(1)		55		55
Total L&S		1,754		1,774
G&P
MarkWest Utica EMG, L.L.C.(1)	57%	712		1,984
Sherwood Midstream LLC(1)	50%	546		537
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(1)	67%	302		302
Rendezvous Gas Services, L.L.C.(1)	78%	167		170
Sherwood Midstream Holdings LLC(1)	52%	155		157
Centrahoma Processing LLC	40%	150		153
Other(1)		206		198
Total G&P		2,238		3,501
Total		$	3,992	$	5,275

(1) Investments deemed to be VIE’s. Some investments included within “Other” have also been deemed to be VIE’s.

(2) During the three months ended March 31, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

For those entities that have been deemed to be VIE’s, 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, since 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, 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 March 31, 2020, MPLX has a 24.1 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 three months ended March 31, 2020.

11

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. During the first quarter of 2020, 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.

Summarized financial information for MPLX’s equity method investments for the three months ended March 31, 2020 and 2019 is as follows:

	Three Months Ended March 31, 2020
(In millions)	VIEs			Non-VIEs		Total
Revenues and other income	$	(217	)	$	337	$	120
Costs and expenses	104			132		236
Income from operations	(321		)	205		(116		)
Net income	(337		)	186		(151		)
(Loss)/income from equity method investments(1)	$	(1,222	)	$	38	$	(1,184	)

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

	Three Months Ended March 31, 2019(1)
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	155	$	391	$	546
Costs and expenses	77		198		275
Income from operations	78		193		271
Net income	71		181		252
Income from equity method investments	$	27	$	50	$	77

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

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

	March 31, 2020
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	320	$	325	$	645
Noncurrent assets	5,384		5,115		10,499
Current liabilities	153		195		348
Noncurrent liabilities	$	544	$	859	$	1,403

	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

12

As of March 31, 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 $60 million, after the impairment charges recognized during the quarter. 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 March 31, 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 March 31, 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 March 31, 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, respectively.

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. Activity on the MPC Loan Agreement was as follows:

(In millions)	Three Months Ended March 31, 2020			Year Ended December 31, 2019
Borrowings	$	1,667		$	8,540
Average interest rate of borrowings	2.833		%	3.441		%
Repayments	$	2,261		$	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:

13

(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 March 31,
(In millions)	2020		2019
Service revenues - related parties
MPC	$	927	$	803
Other	1		—
Total Service revenue - related parties	928		803
Rental income - related parties
MPC	234		325
Product sales - related parties(1)
MPC	33		41
Other income - related parties
MPC	48		10
Other	16		16
Total Other income - related parties	$	64	$	26

(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 months ended March 31, 2020, these sales totaled $173 million. For the three months ended March 31, 2019, these sales totaled $223 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 rent and lease agreements with MPC.

14

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 March 31,
(In millions)	2020		2019
Rental cost of sales - related parties
MPC	$	46	$	43
Purchases - related parties
MPC	271		273
Other	5		5
Total Purchase - related parties	276		278
General and administrative expenses
MPC	$	64	$	62

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 months ended March 31, 2020 and 2019, these charges totaled $36 million and $41 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.

15

(In millions)	March 31, 2020		December 31, 2019
Current assets - related parties
Receivables - MPC	$	538	$	621
Receivables - Other	21		22
Prepaid - MPC	15		9
Lease Receivables - MPC	26		4
Total	600		656
Noncurrent assets - related parties
Long-term receivables - MPC	28		21
Right of use assets - MPC	231		232
Long-term lease receivables - MPC	399		43
Unguaranteed residual asset - MPC	19		7
Total	677		303
Current liabilities - related parties
Payables - MPC	227		911
Payables - Other	16		37
Operating lease liabilities - MPC	1		1
Deferred revenue - Minimum volume deficiencies - MPC	38		42
Deferred revenue - Project reimbursements - MPC	14		16
Deferred revenue - Project reimbursements - Other	1		1
Total	297		1,008
Long-term liabilities - related parties
Long-term operating lease liabilities - MPC	230		230
Long-term deferred revenue - Project reimbursements - MPC	54		53
Long-term deferred revenue - Project reimbursements - Other	6		7
Total	$	290	$	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 three months ended March 31, 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 months ended March 31, 2020 and 2019 include:

	Three Months Ended March 31,
	2020	2019
Common Units	ü	ü
Equity-based compensation awards	ü	ü
Series A preferred units	ü	ü
Series B preferred units	ü
TexNew Mex units	ü

For the three months ended March 31, 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 months ended March 31, 2020 and 2019 were 1 million and less than 1 million, respectively.

	Three Months Ended March 31,
(In millions)	2020			2019
Net income attributable to MPLX LP	$	(2,724	)	$	503
Less: Distributions declared on Series A preferred units(1)	20			20
Distributions declared on Series B preferred units(1)	11			—
Limited partners’ distributions declared on MPLX common units (including common units of general partner)(1)	728			523
Undistributed net loss attributable to MPLX LP	$	(3,483	)	$	(40	)

(1) See Note 7 for distribution information.

	Three Months Ended March 31, 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	$	728		$	20	$	11	$	759
Undistributed net loss attributable to MPLX LP	(3,483		)	—		—		(3,483		)
Net income attributable to MPLX LP(1)	$	(2,755	)	$	20	$	11	$	(2,724	)
Weighted average units outstanding:
Basic	1,058
Diluted	1,058
Net income attributable to MPLX LP per limited partner unit:
Basic	$	(2.60	)
Diluted	$	(2.60	)

(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 March 31, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	523		$	20	$	543
Undistributed net loss attributable to MPLX LP	(40		)	—		(40		)
Net income attributable to MPLX LP(1)	$	483		$	20	$	503
Weighted average units outstanding:
Basic	794
Diluted	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.61
Diluted	$	0.61

(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.

7. Equity

The changes in the number of common units outstanding during the three months ended March 31, 2020 are summarized below:

(In units)	Common
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	151,878
Balance at March 31, 2020	1,058,507,349

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 March 31, 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.

18

(In millions)	Series B Preferred Units
Balance at December 31, 2019	$	611
Net income allocated	11
Distributions received by Series B preferred unitholders	(21		)
Balance at March 31, 2020	$	601

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 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. No distributions were earned by the TexNew Mex units in the first quarter of 2020.

Cash distributions – In accordance with the MPLX partnership agreement, on April 28, 2020, MPLX declared a quarterly cash distribution for the first quarter of 2020, totaling $728 million, or $0.6875 per common unit. This rate will also be received by Series A preferred unitholders. These distributions will be paid on May 15, 2020 to common unitholders of record on May 8, 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. MPLX made a cash distribution to holders of the Series B preferred unitholders in February 2020 for approximately $21 million.

Quarterly distributions for the first quarter of 2020 and 2019 are summarized below:

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

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three months ended March 31, 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 March 31,
(In millions)	2020		2019(1)
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	728	$	523
Series A preferred unit distributions	20		20
Series B preferred unit distributions	11		—
Total cash distributions declared	$	759	$	543

(1) The distribution on common units for the three months ended March 31, 2019 does not include the impact of the issuance of units in connection with the merger.

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 April 28, 2020, MPLX declared a quarterly cash distribution of $0.6875 per common unit for the first 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.

19

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 March 31, 2020. The changes in the redeemable preferred balance from December 31, 2019 through March 31, 2020 are summarized below:

(In millions)	Redeemable Series A Preferred Units
Balance at December 31, 2019	$	968
Net income allocated	20
Distributions received by Series A preferred unitholders	(20		)
Balance at March 31, 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 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.

20

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 March 31,
(In millions)	2020			2019(1)
L&S
Service revenue	$	1,004		$	889
Rental income	242			335
Product related revenue	19			15
Income from equity method investments	50			45
Other income	51			12
Total segment revenues and other income(2)	1,366			1,296
Segment Adjusted EBITDA(3)	872			559
Capital expenditures	184			198
Investments in unconsolidated affiliates	54			7
G&P
Service revenue	536			528
Rental income	88			89
Product related revenue	222			276
(Loss)/income from equity method investments	(1,234		)	32
Other income	14			14
Total segment revenues and other (loss)/income(2)	(374		)	939
Segment Adjusted EBITDA(3)	422			371
Capital expenditures	134			306
Investments in unconsolidated affiliates	$	37		$	128

(1) Financial information for the first quarter of 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 $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

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

(In millions)	March 31, 2020		December 31, 2019
Segment assets
Cash and cash equivalents	$	57	$	15
L&S	20,891		20,810
G&P	16,058		19,605
Total assets	$	37,006	$	40,430

21

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

	Three Months Ended March 31,
(In millions)	2020			2019(1)
Reconciliation to Net (loss)/income:
L&S Segment Adjusted EBITDA	$	872		$	559
G&P Segment Adjusted EBITDA	422			371
Total reportable segments	1,294			930
Depreciation and amortization(2)	(325		)	(301		)
Benefit for income taxes	—			1
Amortization of deferred financing costs	(14		)	(7		)
Non-cash equity-based compensation	(5		)	(7		)
Impairment expense	(2,165		)	—
Net interest and other financial costs	(216		)	(217		)
(Loss)/income from equity method investments	(1,184		)	77
Distributions/adjustments related to equity method investments	(124		)	(122		)
Unrealized derivative gains/(losses)(3)	15			(4		)
Acquisition costs	—			(1		)
Other	(1		)	—
Adjusted EBITDA attributable to noncontrolling interests	9			7
Adjusted EBITDA attributable to Predecessor(4)	—			333
Net (loss)/income	$	(2,716	)	$	689

(1) Financial information for the first quarter of 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 $126 million for the three months ended March 31, 2020 and 2019, respectively. Depreciation and amortization attributable to G&P was $187 million and $175 million for the three months ended March 31, 2020 and 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)	March 31, 2020		December 31, 2019
NGLs	$	1	$	5
Line fill	6		10
Spare parts, materials and supplies	98		95
Total inventories	$	105	$	110

22

11. Property, Plant and Equipment

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

(In millions)	Estimated Useful Lives	March 31, 2020		December 31, 2019
L&S
Pipelines	2-51 years	$	5,637	$	5,572
Refining Logistics	13-40 years	2,308		2,870
Terminals	2-40 years	1,176		1,109
Marine	15-20 years	960		906
Land, building and other	1-61 years	1,827		1,817
Construction-in progress		618		660
Total L&S property, plant and equipment		12,526		12,934
G&P
Gathering and transportation	5-40 years	7,349		7,159
Processing and fractionation	15-40 years	5,605		5,545
Land, building and other	3-40 years	491		484
Construction-in-progress		616		745
Total G&P property, plant and equipment		14,061		13,933
Total property, plant and equipment		26,587		26,867
Less accumulated depreciation(1)		4,758		4,722
Property, plant and equipment, net		$	21,829	$	22,145

(1) The March 31, 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.

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. 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. 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.

23

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 is 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 March 31, 2020	7,722		—			7,722
Gross goodwill as of March 31, 2020	7,722		3,141			10,863
Accumulated impairment losses	—		(3,141		)	(3,141		)
Balance as of March 31, 2020	$	7,722	$	—		$	7,722

24

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 were 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 March 31, 2020 and December 31, 2019 is shown below:

		March 31, 2020							December 31, 2019
(In millions)	Useful Life	Gross		Accumulated Amortization(1)(2)			Net		Gross		Accumulated Amortization			Net
L&S	6 - 8 years	$	283	$	(54	)	$	229	$	283	$	(45	)	$	238
G&P	6 - 25 years	1,288		(462		)	826		1,288		(256		)	1,032
		$	1,571	$	(516	)	$	1,055	$	1,571	$	(301	)	$	1,270

(1) Amortization expense attributable to the G&P and L&S segments for the three months ended March 31, 2020 was $29 million and $9 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 March 31, 2020 is as follows:

(In millions)
2020	$	96
2021	128
2022	128
2023	128
2024	124
Thereafter	451
Total	$	1,055

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 March 31, 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.

	March 31, 2020					December 31, 2019
(In millions)	Assets		Liabilities			Assets		Liabilities
Significant unobservable inputs (Level 3)
Embedded derivatives in commodity contracts	$	—	$	(45	)	$	—	$	(60	)
Total carrying value on Consolidated Balance Sheets	$	—	$	(45	)	$	—	$	(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 $0.26 to $0.68 per gallon with a weighted average of $0.39 per gallon per the

25

current term of the embedded derivative and (2) the probability of renewal of 95 percent for the first five-year term and 83.5 percent for the second five-year term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. An increase in the probability of renewal would result in an increase in the fair value of the related embedded derivative liability. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of March 31, 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 March 31, 2020					Three Months Ended March 31, 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)	—		14			—		(6		)
Settlements	—		1			—		2
Fair value at end of period	—		(45		)	—		(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	$	—	$	13		$	—	$	(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:

	March 31, 2020				December 31, 2019
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-term debt	$	18,352	$	20,560	$	21,054	$	19,800
SMR liability	$	77	$	79	$	90	$	80

26

14. Derivative Financial Instruments

As of March 31, 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, the probability of the producer customer exercising its option to extend and the estimated favorability of these contracts compared to current market conditions. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. As of March 31, 2020 and December 31, 2019, the estimated fair value of this contract was a liability of $45 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 March 31, 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)	March 31, 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	$	—	$	(2	)	$	—	$	(5	)
Other noncurrent assets / Deferred credits and other liabilities	—		(43		)	—		(55		)
Total	$	—	$	(45	)	$	—	$	(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 March 31,
(In millions)	2020			2019
Product sales
Realized (loss)/gain	$	—		$	—
Unrealized (loss)/gain	—			—
Product sales derivative (loss)/gain	—			—
Purchased product costs
Realized (loss)/gain	(1		)	(2		)
Unrealized gain/(loss)	15			(4		)
Purchased product costs derivative gain/(loss)	14			(6		)
Cost of revenues
Realized (loss)/gain	—			—
Unrealized (loss)/gain	—			—
Cost of revenues derivative (loss)/gain	—			—
Total derivative gain/(loss)	$	14		$	(6	)

27

15. Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	March 31, 2020			December 31, 2019
MPLX LP:
Bank revolving credit facility	$	750		$	—
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)	14			19
Total	20,864			20,119
Unamortized debt issuance costs	(103		)	(106		)
Unamortized discount/premium	(290		)	(300		)
Amounts due within one year	(4		)	(9		)
Total long-term debt due after one year	$	20,467		$	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 three months ended March 31, 2020, MPLX borrowed $1,325 million under the MPLX Credit Agreement, at an average interest rate of 2.139 percent, and repaid $575 million. At March 31, 2020, MPLX had $750 million in outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of $2.75 billion, or 78.6 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 March 31, 2020, MPLX had drawn $1.0 billion on the term loan at an average interest rate of 2.273 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.

28

16. Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three months ended March 31, 2020 and 2019:

	Three Months Ended March 31, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	84	$	528	$	612
Service revenue - related parties	920		8		928
Service revenue - product related	—		39		39
Product sales	15		154		169
Product sales - related parties	4		29		33
Total revenues from contracts with customers	$	1,023	$	758	1,781
Non-ASC 606 (loss)/revenue(1)					(789		)
Total revenues and other income					$	992

	Three Months Ended March 31, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	86	$	528	$	614
Service revenue - related parties	803		—		803
Service revenue - product related	—		34		34
Product sales	11		205		216
Product sales - related parties	4		37		41
Total revenues from contracts with customers	$	904	$	804	1,708
Non-ASC 606 revenue(1)					527
Total revenues and other income					$	2,235

(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 first quarter of 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,

29

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 three-month periods ended March 31, 2020 and 2019:

(In millions)	Balance at December 31, 2019(1)		Additions/ (Deletions)			Revenue Recognized(2)			Balance at March 31, 2020
Contract assets	$	39	$	(27	)	$	—		$	12
Deferred revenue	23		5			(3		)	25
Deferred revenue - related parties	53		12			(16		)	49
Long-term deferred revenue	90		6			—			96
Long-term deferred revenue - related parties	$	55	$	1		$	—		$	56

(In millions)	Balance at December 31, 2018(1)		Additions/ (Deletions)(3)			Revenue Recognized(2)(3)			Balance at March 31, 2019(3)
Contract assets	$	36	$	(17	)	$	—		$	19
Deferred revenue	13		1			(1		)	13
Deferred revenue - related parties	65		9			(16		)	58
Long-term deferred revenue	56		1			—			57
Long-term deferred revenue - related parties	$	52	$	—		$	—		$	52

(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 first quarter of 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 March 31, 2020, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $224 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	$	1,344
2021	1,747
2022	1,717
2023	1,638
2024 and thereafter	5,662
Total revenue on remaining performance obligations(1),(2),(3)	$	12,108

(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.

30

17. Supplemental Cash Flow Information

	Three Months Ended March 31,
(In millions)	2020			2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	210		$	173
Non-cash investing and financing activities:
Net transfers of property, plant and equipment from (to) 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:

	Three Months Ended March 31,
(In millions)	2020			2019
(Decrease)/increase in capital accruals	$	(61	)	$	(71	)

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 March 31, 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 March 31, 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 March 31, 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 March 31, 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.

31

19. Equity-Based Compensation

Phantom Units

The following is a summary of phantom unit award activity of MPLX LP common units for the three months ended March 31, 2020:

	Number of Units		Weighted Average Fair Value
Outstanding at December 31, 2019	1,109,568		$	35.97
Granted	168,212		20.49
Settled	(174,888	)	36.29
Forfeited	(335	)	33.55
Outstanding at March 31, 2020	1,102,557		$	33.56

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 three months ended March 31, 2020:

	Number of Units
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	(1,169,354	)
Forfeited	(18,750	)
Outstanding at March 31, 2020	3,116,454

32

20. Leases

For the three months ended March 31, 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 three months ended March 31, 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 March 31, 2020				Three Months Ended March 31, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	186	$	63	$	279	$	65
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		N/A		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		N/A		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	N/A		N/A		N/A

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

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

The following is a schedule of future payments on the sales-type leases with MPC as of March 31, 2020:

(In millions)	Related Party
2020	$	129
2021	157
2022	157
2023	158
2024	158
2025 and thereafter	461
Total minimum future rentals	1,220
Less: present value discount	795
Lease receivable	$	425

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.

33

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 March 31, 2020 and December 31, 2019, accrued liabilities for remediation totaled $17 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 March 31, 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 that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system, 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 ordered the U.S. Army Corps of Engineers, 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. If the permit is vacated pending completion of the EIS and the vacatur is deemed temporary, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes while the pipeline is shutdown and 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 court vacates the permit and such action 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, if any. As of March 31, 2020, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $230 million.

Contractual Commitments and Contingencies – At March 31, 2020, MPLX’s contractual commitments to acquire property, plant and equipment totaled $318 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 March 31, 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.

34

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 recent 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;

35

• 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; and

• 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, including the dropdowns completed by MPC, 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 “Item 1A. Risk Factors” below, together with the risk factors described in our Annual Report on Form 10-K for the year ended December 31, 2019. 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.

36

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 March 31, 2020 and March 31, 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) Q1 2020 includes impairment related to equity method investments of approximately $1.3 billion within our G&P operating segment.

(2) Q1 2020 includes impairment related to equity method investments of approximately $1.3 billion, goodwill impairment of approximately $1.8 billion and long-lived asset impairments of approximately $0.3 billion, all within our G&P operating segment.

(3) Q1 2019 includes Adjusted EBITDA attributable to Predecessor and portion of DCF adjustments attributable to Predecessor.

Other Highlights

• Recognized approximately $3.4 billion of impairments during the quarter related to goodwill, equity method investments and long-lived assets (including intangibles).

• MPC announced the unanimous decision of its board of directors to maintain MPC’s current midstream structure, with MPC remaining the general partner of MPLX. This was a result of a comprehensive evaluation by a special committee formed by MPC’s board of directors, which included extensive input from multiple external advisors and significant feedback from investors.

• MPLX continues to focus on portfolio optimization, which could include asset divestitures.

RECENT DEVELOPMENTS

• Announced plans to reduce 2020 capital spending to approximately $1.0 billion and expect to reduce forecasted annual operating expenses by approximately $200 million. Reduction in capital spending is primarily related to the BANGL project which is no longer being pursued as the company works with others to optimize existing pipeline capacity while continuing to meet producers’ needs for flow assurance and future growth. The reduction in operating expenses will be achieved through the deferral of certain expense projects.

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

37

CURRENT ECONOMIC ENVIRONMENT

The recent 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

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.

38

COMPARABILITY OF OUR FINANCIAL RESULTS

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

RESULTS OF OPERATIONS

The following tables and discussion are a summary of our results of operations for the three months ended March 31, 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 March 31,
(In millions)	2020			2019			Variance
Total revenues and other income(1)	$	992		$	2,235		$	(1,243	)
Costs and expenses:
Cost of revenues (excludes items below)	368			339			29
Purchased product costs	135			194			(59		)
Rental cost of sales	35			37			(2		)
Rental cost of sales - related parties	46			43			3
Purchases - related parties	276			278			(2		)
Depreciation and amortization	325			301			24
Impairment expense	2,165			—			2,165
General and administrative expenses	97			101			(4		)
Other taxes	31			30			1
Total costs and expenses	3,478			1,323			2,155
Income/(loss) from operations	(2,486		)	912			(3,398		)
Related party interest and other financial costs	3			1			2
Interest expense, net of amounts capitalized	211			214			(3		)
Other financial costs	16			9			7
Income/(loss) before income taxes	(2,716		)	688			(3,404		)
(Benefit)/provision for income taxes	—			(1		)	1
Net income/(loss)	(2,716		)	689			(3,405		)
Less: Net income attributable to noncontrolling interests	8			6			2
Less: Net income attributable to Predecessor	—			180			(180		)
Net income/(loss) attributable to MPLX LP	(2,724		)	503			(3,227		)
Adjusted EBITDA attributable to MPLX LP (excluding Predecessor results)(2)	1,294			930			364
Adjusted EBITDA attributable to MPLX LP (including Predecessor results)(3)	N/A			1,263			N/A
DCF attributable to GP and LP unitholders (including Predecessor results)(3)	$	1,047		$	991		$	56

(1) Includes impairment expense of approximately $1.3 billion related to three equity method investments in 2020.

(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.

39

	Three Months Ended March 31,
(In millions)	2020			2019			Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income:
Net income	$	(2,716	)	$	689		$	(3,405	)
Provision for income taxes	—			(1		)	1
Amortization of deferred financing costs	14			7			7
Net interest and other financial costs	216			217			(1		)
Income from operations	(2,486		)	912			(3,398		)
Depreciation and amortization	325			301			24
Non-cash equity-based compensation	5			7			(2		)
Impairment expense	2,165			—			2,165
Loss (Income) from equity method investments	1,184			(77		)	1,261
Distributions/adjustments related to equity method investments	124			122			2
Unrealized derivative (gains)/losses(1)	(15		)	4			(19		)
Acquisition costs	—			1			(1		)
Other	1			—			1
Adjusted EBITDA	1,303			1,270			33
Adjusted EBITDA attributable to noncontrolling interests	(9		)	(7		)	(2		)
Adjusted EBITDA attributable to Predecessor(2)	—			(333		)	333
Adjusted EBITDA attributable to MPLX LP(3)	1,294			930			364
Deferred revenue impacts	23			9			14
Net interest and other financial costs	(216		)	(217		)	1
Maintenance capital expenditures	(34		)	(37		)	3
Maintenance capital expenditures reimbursements	14			7			7
Equity method investment capital expenditures paid out	(7		)	(4		)	(3		)
Other	4			—			4
Portion of DCF adjustments attributable to Predecessor(2)	—			69			(69		)
DCF	1,078			757			321
Preferred unit distributions	(31		)	(30		)	(1		)
DCF attributable to GP and LP unitholders	1,047			727			320
Adjusted EBITDA attributable to Predecessor(2)	—			333			(333		)
Portion of DCF adjustments attributable to Predecessor(2)	—			(69		)	69
DCF attributable to GP and LP unitholders (including Predecessor results)	$	1,047		$	991		$	56

(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 March 31, 2020, the L&S and G&P segments made up $872 million and $422 million of Adjusted EBITDA attributable to MPLX LP, respectively. For the three months ended March 31, 2019, the L&S and G&P segments made up $559 million and $371 million of Adjusted EBITDA attributable to MPLX LP, respectively.

40

	Three Months Ended March 31,
(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	$	1,009		$	853		$	156
Changes in working capital items	112			196			(84		)
All other, net	(30		)	(15		)	(15		)
Non-cash equity-based compensation	5			7			(2		)
Net gain/(loss) on disposal of assets	—			(1		)	1
Net interest and other financial costs	216			217			(1		)
Current income taxes	—			1			(1		)
Unrealized derivative (gains)/losses(1)	(15		)	4			(19		)
Acquisition costs	—			1			(1		)
Other adjustments to equity method investment distributions	5			7			(2		)
Other	1			—			1
Adjusted EBITDA	1,303			1,270			33
Adjusted EBITDA attributable to noncontrolling interests	(9		)	(7		)	(2		)
Adjusted EBITDA attributable to Predecessor(2)	—			(333		)	333
Adjusted EBITDA attributable to MPLX LP(3)	1,294			930			364
Deferred revenue impacts	23			9			14
Net interest and other financial costs	(216		)	(217		)	1
Maintenance capital expenditures	(34		)	(37		)	3
Maintenance capital expenditures reimbursements	14			7			7
Equity method investment capital expenditures paid out	(7		)	(4		)	(3		)
Other	4			—			4
Portion of DCF adjustments attributable to Predecessor(2)	—			69			(69		)
DCF	1,078			757			321
Preferred unit distributions	(31		)	(30		)	(1		)
DCF attributable to GP and LP unitholders	1,047			727			320
Adjusted EBITDA attributable to Predecessor(2)	—			333			(333		)
Portion of DCF adjustments attributable to Predecessor(2)	—			(69		)	69
DCF attributable to GP and LP unitholders (including Predecessor results)	$	1,047		$	991		$	56

(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 March 31, 2020, the L&S and G&P segments made up $872 million and $422 million of Adjusted EBITDA attributable to MPLX LP, respectively. For the three months ended March 31, 2019, the L&S and G&P segments made up $559 million and $371 million of Adjusted EBITDA attributable to MPLX LP, respectively.

Three months ended March 31, 2020 compared to three months ended March 31, 2019

Total revenues and other income decreased $1,243 million in the first quarter 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. The remaining increase of $21 million was primarily due to a $32 million increase in pipeline transportation volumes, prices and fees; $5 million from increased fees and shell capacity from Refining Logistics; a $13 million increase from additional marine vessels; $5 million from decreased expenses on the Explorer pipeline; and $38 million

41

from higher fees as a result of higher volumes in the Marcellus, Southwest, Bakken and Rockies. These increases were partially offset by a decrease of $71 million due to lower prices, primarily in the Southwest, Southern Appalachia and Marcellus.

Cost of Revenues increased $29 million in the first quarter of 2020 compared to the same period of 2019, primarily due to higher project-related costs, which include repairs, maintenance and operating cost, in the L&S segment as well as in the Marcellus region within the G&P segment. These were partially offset by lower repairs, maintenance and operating costs in the Southwest, Southern Appalachia and Rockies regions in the G&P segment and lower miscellaneous costs and expenses within the L&S segment.

Purchased product costs decreased $59 million in the first quarter of 2020 compared to the same period of 2019. This was primarily due to lower prices of $46 million in the Southwest and Southern Appalachia, partially offset by higher volumes of $6 million in the Southwest. In addition, there was a decrease of $18 million in unrealized derivative gains from prior year.

Depreciation and amortization expense increased $24 million in the first quarter of 2020 compared to the same period of 2019, primarily due to additions to in-service property, plant and equipment throughout 2019 and the first three months of 2020 as well as accelerated depreciation of certain gathering assets, partially offset by a decrease due to the classification of certain assets as a sales-type lease.

Impairment expense increased $2,165 million in the first quarter 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.

Net interest expense and other financial costs increased $6 million in the first quarter of 2020 compared to the same period of 2019. The increase is primarily related to costs associated with debt facilities that were entered into during the second half of 2019

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 months ended March 31, 2020 and 2019. Prior period financial information has been retrospectively adjusted for common control transactions.

42

L&S Segment

(1) Includes adjusted EBITDA attributable to Predecessor.

	Three Months Ended March 31,
(In millions)	2020			2019			Variance
Service revenue	$	1,004		$	889		$	115
Rental income	242			335			(93		)
Product related revenue	19			15			4
Income from equity method investments	50			45			5
Other income	51			12			39
Total segment revenues and other income	1,366			1,296			70
Cost of revenues	238			226			12
Purchases - related parties	199			190			9
Depreciation and amortization	138			126			12
General and administrative expenses	52			51			1
Other taxes	16			16			—
Segment income from operations	723			687			36
Depreciation and amortization	138			126			12
Income from equity method investments	(50		)	(45		)	(5		)
Distributions/adjustments related to equity method investments	57			54			3
Acquisition costs	—			1			(1		)
Non-cash equity-based compensation	3			5			(2		)
Other	1			—			1
Adjusted EBITDA attributable to Predecessor	—			(269		)	269
Segment adjusted EBITDA(1)	872			559			313
Capital expenditures	184			198			(14		)
Investments in unconsolidated affiliates	$	54		$	7		$	47

(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 March 31, 2020 compared to three months ended March 31, 2019

Service revenue increased $115 million in the first quarter of 2020 compared to the same period of 2019. This was primarily due to a $55 million increase due to the classification of lease income between service revenue, rental income and other income based on the nature of the contract; a $32 million increase in pipeline transportation volumes, prices and fees; $5 million from increased fees and shell capacity from Refining Logistics; a $13 million increase from additional marine vessels; and $10 million from various immaterial items.

43

Rental income decreased $93 million in the first quarter of 2020 compared to the same period of 2019, primarily due to a net decrease of $93 million due to the classification of lease income between service revenue, rental income and other income based on the nature of the contract.

Income from equity method investments increased $5 million in the first quarter of 2020 compared to the same period of 2019, primarily due to lower expenses on the Explorer pipeline.

Other Income increased $39 million in the first quarter of 2020 compared to the same period of 2019, primarily due to an increase of $38 million due to the classification of lease income between service revenue, rental income and other income based on the nature of the contract.

Cost of Revenues increased $12 million in the first quarter of 2020 compared to the same period of 2019, primarily due to higher project-related costs partially offset by lower other miscellaneous expenses.

Purchases - related parties increased $9 million in the first quarter of 2020 compared to the same period of 2019, primarily due to increased employee-related costs and other miscellaneous expenses from MPC partially offset by higher reimbursements from MPC for reimbursable projects.

Depreciation and amortization increased $12 million in the first quarter of 2020 compared to the same period of 2019, primarily due to additions to in-service property, plant and equipment throughout 2019 and the first quarter of 2020 partially offset by a decrease due to the classification of certain assets as a sales-type lease.

G&P Segment

(1) Includes impairment of equity method investments of $1,264 million.

(2) Includes impairment of goodwill of $1,814 million, long-lived assets including intangibles of $351 million and equity method investments of $1,264 million.

(3) Includes adjusted EBITDA attributable to Predecessor.

44

	Three Months Ended March 31,
(In millions)	2020			2019			Variance
Service revenue	$	536		$	528		$	8
Rental income	88			89			(1		)
Product related revenue	222			276			(54		)
(Loss)/income from equity method investments	(1,234		)	32			(1,266		)
Other income	14			14			—
Total segment revenues and other (loss)/income	(374		)	939			(1,313		)
Cost of revenues	211			193			18
Purchased product costs	135			194			(59		)
Purchases - related parties	77			88			(11		)
Depreciation and amortization	187			175			12
Impairment expense	2,165			—			2,165
General and administrative expenses	45			50			(5		)
Other taxes	15			14			1
Segment (loss)/income from operations	(3,209		)	225			(3,434		)
Depreciation and amortization	187			175			12
Impairment expense	2,165			—			2,165
Loss/(income) from equity method investments	1,234			(32		)	1,266
Distributions/adjustments related to equity method investments	67			68			(1		)
Unrealized derivative (gains)/losses(1)	(15		)	4			(19		)
Non-cash equity-based compensation	2			2			—
Adjusted EBITDA attributable to Predecessor	—			(64		)	64
Adjusted EBITDA attributable to noncontrolling interests	(9		)	(7		)	(2		)
Segment Adjusted EBITDA(2)	422			371			51
Capital expenditures	134			306			(172		)
Investments in unconsolidated affiliates	$	37		$	128		$	(91	)

(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) 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 March 31, 2020 compared to three months ended March 31, 2019

Service revenue increased $8 million in the first quarter of 2020 compared to the same period of 2019. This was primarily due to higher fees from higher volumes in the Marcellus, Southwest and Bakken of $30 million, offset by lower volumes of $5 million in the Rockies as well as other miscellaneous decreases.

Product related revenue decreased $54 million in the first quarter of 2020 compared to the same period of 2019. This was primarily due to lower prices in the Southwest, Southern Appalachia and Marcellus of approximately $71 million. This was partially offset by $13 million of volume increases in the Southwest, Marcellus, Bakken and Rockies as well as other miscellaneous increases.

Income from equity method investments decreased $1,266 million in the first quarter 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. Additionally, there was a decrease in various joint ventures due to lower volumes processed and lower NGL prices compared to the same period of 2019, offset by an increase in the Sherwood Midstream LLC joint venture due to additional plants coming online during 2019.

45

Cost of revenues increased $18 million in the first quarter 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 $59 million in the first quarter of 2020 compared to the same period of 2019. This was primarily due to lower prices of $46 million in the Southwest and Southern Appalachia, partially offset by higher costs from higher volumes of $6 million in the Southwest. In addition, there was an increase of $18 million in unrealized derivative gains from prior year.

Purchases - related parties decreased $11 million in the first 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.

Depreciation and amortization increased $12 million in the first quarter of 2020 compared to the same period of 2019, with the majority of the increase being due to additions to in-service property, plant and equipment throughout 2019 and the first three months of 2020 as well as accelerated depreciation of certain gathering assets.

Impairment expense increased $2,165 million in first quarter 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 $5 million in the first quarter of 2020 compared to the same period of 2019, primarily 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.

46

OPERATING DATA⁽¹⁾

	Three Months Ended   March 31,
	2020		2019
L&S
Pipeline throughput (mbpd)
Crude oil pipelines	3,210		3,105
Product pipelines	1,905		1,897
Total pipelines	5,115		5,002
Average tariff rates ($ per barrel)(2)
Crude oil pipelines	$	0.93	$	0.96
Product pipelines	0.79		0.68
Total pipelines	$	0.88	$	0.85
Terminal throughput (mbpd)	2,966		3,220
Marine Assets (number in operation)(3)
Barges	305		256
Towboats	23		23

47

	Three Months Ended   March 31, 2020
	MPLX LP(4)	MPLX LP Operated(5)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,420	1,420
Utica Operations	—	1,800
Southwest Operations	1,557	1,601
Bakken Operations	156	156
Rockies Operations	592	775
Total gathering throughput	3,725	5,752
Natural Gas Processed (MMcf/d)
Marcellus Operations	4,198	5,522
Utica Operations	—	648
Southwest Operations	1,648	1,679
Southern Appalachian Operations	243	243
Bakken Operations	156	156
Rockies Operations	539	539
Total natural gas processed	6,784	8,787
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(6)	456	456
Utica Operations(6)	—	34
Southwest Operations	15	15
Southern Appalachian Operations(7)	12	12
Bakken Operations	31	31
Rockies Operations	5	5
Total C2 + NGLs fractionated(8)	519	553

48

	Three Months Ended   March 31, 2019
	MPLX LP(4)	MPLX LP Operated(5)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,282	1,282
Utica Operations	—	2,109
Southwest Operations	1,581	1,581
Bakken Operations	152	152
Rockies Operations	642	827
Total gathering throughput	3,657	5,951
Natural Gas Processed (MMcf/d)
Marcellus Operations	4,152	5,148
Utica Operations	—	817
Southwest Operations	1,599	1,599
Southern Appalachian Operations	235	235
Bakken Operations	152	152
Rockies Operations	570	570
Total natural gas processed	6,708	8,521
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(6)	420	420
Utica Operations(6)	—	44
Southwest Operations	17	17
Southern Appalachian Operations(7)	13	13
Bakken Operations	16	16
Rockies Operations	4	4
Total C2 + NGLs fractionated(8)	470	514

	Three Months Ended   March 31,
	2020		2019
Pricing Information
Natural Gas NYMEX HH ($ per MMBtu)	$	1.87	$	2.87
C2 + NGL Pricing ($ per gallon)(9)	$	0.40	$	0.62

(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 190 mbpd and 189 mbpd of total MPLX Operated, fractionated products for the three months ended March 31, 2020 and 2019, respectively. Purity ethane makes up approximately 183 mbpd and 176 mbpd of total MPLX LP consolidated, fractionated products for the three months ended March 31, 2020 and 2019, respectively.

(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.

49

LIQUIDITY AND CAPITAL RESOURCES

Cash Flows

Our cash and cash equivalents was $57 million at March 31, 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:

	Three Months Ended March 31,
(In millions)	2020			2019
Net cash provided by (used in):
Operating activities	$	1,009		$	853
Investing activities	(362		)	(700		)
Financing activities	(605		)	(116		)
Total	$	42		$	37

Net cash provided by operating activities increased $156 million in the first three months of 2020 compared to the first three months of 2019, primarily due to increased net income of $24 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 $338 million in the first three months of 2020 compared to the first three months of 2019, primarily due to decreased spending related to the capital budget, a return of capital from our investment in Wink to Webster, decreased contributions to equity method investments as well as cash received from the sale of certain assets.

Financing activities were a $605 million use of cash in the first three months of 2020 compared to a $116 million use of cash in the first three months of 2019. The use of cash for the first three months of 2020 was primarily due to distributions of $717 million to common unitholders, distributions of $20 million to Series A preferred unitholders, distributions of $21 million to Series B preferred unitholders, distributions of $9 million to noncontrolling interests, repayment of $575 million on the MPLX Credit Agreement, payments of $6 million related to financing leases, and repayment of $2,261 million on the MPC Loan Agreement. These uses of cash were offset by borrowings of $1,325 million on the revolving credit facility, $1,667 million on the MPC Loan Agreement, and $14 million of contributions from MPC.

Debt and Liquidity Overview

Our outstanding borrowings at March 31, 2020 consist of the following:

(In millions)	March 31, 2020
MPLX LP:
Bank revolving credit facility	750
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	14
Total	20,864
Unamortized debt issuance costs	(103		)
Unamortized discount/premium	(290		)
Amounts due within one year	(4		)
Total long-term debt due after one year	$	20,467

50

Our intention is to maintain an investment grade credit profile. As of April 23, 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 March 31, 2020, we were in compliance with the covenants, including the financial covenant with a ratio of Consolidated Total Debt to Consolidated EBITDA of 3.8 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 $4.3 billion at March 31, 2020 consisting of:

	March 31, 2020
(In millions)	Total Capacity		Outstanding Borrowings			Available Capacity
Bank revolving credit facility due 2024(1)	$	3,500	$	(750	)	$	2,750
MPC Loan Agreement	1,500		—			1,500
Total liquidity	$	5,000	$	(750	)	4,250
Cash and cash equivalents						57
Total liquidity						$	4,307

(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.

51

Equity and Preferred Units Overview

Common units

The table below summarizes the changes in the number of units outstanding through March 31, 2020:

(In units)
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	151,878
Balance at March 31, 2020	1,058,507,349

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 three months ended March 31, 2020, we issued no common units under our ATM program. As of March 31, 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 $1,111 million per year, based on the number of common units outstanding at March 31, 2020. On April 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 May 15, 2020 to unitholders of record on May 8, 2020. This is consistent with the fourth quarter 2019 distribution of $0.6875 per unit and an increase of 4.6 percent over the first 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. MPLX made a cash distribution to holders of the Series B preferred unitholders in February 2020 for approximately $21 million.

The allocation of total quarterly cash distributions is as follows for the three months ended March 31, 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 March 31,
(In millions)	2020		2019
Distribution declared:
Limited partner units - public	$	270	$	191
Limited partner units - MPC	458		332
Total LP distribution declared	728		523
Series A preferred units	20		20
Series B preferred units	11		—
Total distribution declared	759		543
Cash distributions declared per limited partner common unit	$	0.6875	$	0.6575

52

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:

	Three Months Ended March 31,
(In millions)	2020			2019
Capital expenditures:
Maintenance	$	34		$	37
Maintenance reimbursements	(14		)	(7		)
Growth	284			467
Growth reimbursements	—			(5		)
Total capital expenditures	304			492
Less: Increase (decrease) in capital accruals	(61		)	(71		)
Additions to property, plant and equipment, net of reimbursements(1)	365			563
Investments in unconsolidated affiliates	91			135
Acquisitions	—			(1		)
Total capital expenditures and acquisitions	456			697
Less: Maintenance capital expenditures (including reimbursements)	20			30
Acquisitions	—			(1		)
Total growth capital expenditures(2)	$	436		$	668

(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 three months ended March 31, 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 joint venture which is reflected in the investing section of our statement of cash flows for the three months ended March 31, 2020.

Contractual Cash Obligations

As of March 31, 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 three months ended March 31, 2020, our third-party, long-term debt obligations increased by $750 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.

53

TRANSACTIONS WITH RELATED PARTIES

At March 31, 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, and excluding losses for impairment of equity method investments, MPC accounted for 55 percent and 53 percent of our total revenues and other income for the first 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, excluding impairment expense, MPC accounted for 29 percent and 29 percent for the first 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 March 31, 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 March 31, 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, 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.

54

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.

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. 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.

The “Current Economic Environment” section describes the effects that the recent outbreak of COVID-19 and its development into a pandemic and the recent decline in commodity prices have had on our business. Due to these developments, 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

55

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.

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 March 31, 2020 we had $3,992 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.

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 March 31, 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 months ended March 31, 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.

56

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, the probability of the producer customer exercising its option to extend and the estimated favorability of these contracts compared to current market conditions. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. As of March 31, 2020 and December 31, 2019, the estimated fair value of this contract was a liability of $45 million and $60 million, respectively.

Open Derivative Positions and Sensitivity Analysis

As of March 31, 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 March 31, 2020(1)		Change in Fair Value(2)		Change in Income Before Income Taxes for the Three Months Ended March 31, 2020(3)
Long-term debt
Fixed-rate	$	14,638	$	1,249	N/A
Variable-rate	$	3,714	$	37	$	8

(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 March 31, 2020.

(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 three months ended March 31, 2020.

At March 31, 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 March 31, 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 March 31, 2020, the end of the period covered by this report.

57

Changes in Internal Control Over Financial Reporting

During the quarter ended March 31, 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.

Litigation

In connection with our 9.19 percent indirect interest in a joint venture that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system, 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 ordered the U.S. Army Corps of Engineers, 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. If the permit is vacated pending completion of the EIS and the vacatur is deemed temporary, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes while the pipeline is shutdown and 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 court vacates the permit and such action 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, if any.

Environmental Proceedings

On April 10, 2020, we received a Notice of Probable Violation and Proposed Civil Penalty from the Pipeline and Hazardous Materials Safety Administration’s Office of Pipeline Safety (OPS) for alleged violations arising from the release at the Hospah Station pump station in New Mexico on September 7, 2018. The NOPV alleged a failure to follow written procedures for responding to, investigating, and correcting the cause of an increase in pressure of flow rate outside its normal operating limits, and a failure to follow appropriate procedures regarding related personnel performance. This matter was resolved for a cash penalty of approximately $236,000.

Item 1A. Risk Factors

Except as described below, 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.

The recent outbreak of COVID-19 and certain developments in the global oil markets have had, and may continue to have, material adverse consequences for general economic, financial and business conditions, and could materially and adversely affect our business, financial condition, results of operations and cash flows and those of our customers, suppliers and other counterparties.

The recent outbreak of COVID-19 and the responses of governmental authorities, companies and the self-imposed restrictions by many individuals across the world to stem the spread of the virus have significantly reduced global economic activity, as there has been a dramatic decrease in the number of businesses open for operation and substantially fewer people across the world have been traveling to work or leaving their home to purchase goods and services. This has also resulted, for example, in a dramatic reduction in airline flights and has reduced the number of cars on the road. As a result, there has been a decline in the demand for the fuels distribution services we provide and for the petroleum products that we transport and store.

58

Concerns over the negative effects of COVID-19 on economic and business prospects across the world have contributed to increased market and oil price volatility and have diminished expectations for the global economy. These factors, coupled with the emergence of decreasing business and consumer confidence and increasing unemployment resulting from the COVID-19 outbreak and the recent abrupt oil price decline, may precipitate a prolonged economic slowdown and recession. Any such prolonged period of economic slowdown or recession, or a protracted period of depressed prices for crude oil or refined petroleum products could have significant adverse consequences for our financial condition and the financial condition of our customers, suppliers and other counterparties, and could diminish our liquidity or trigger additional impairments.

The ultimate extent of the impact of COVID-19 on our business, financial condition, results of operations and cash flows will depend largely on future developments, including the duration and spread of the outbreak, particularly within the geographic areas where we operate, the related impact on overall economic activity and the timing of the lifting of restrictions and return of customer confidence, all of which are uncertain and cannot be predicted with certainty at this time.

The Court of Chancery of the State of Delaware will be, to the extent permitted by law, the sole and exclusive forum for substantially all disputes between us and our limited partners.

Our limited partnership agreement provides that the Court of Chancery of the State of Delaware will be the sole and exclusive forum for any claims, actions or proceedings:

• arising out of or relating in any way to our limited partnership agreement, or the rights or powers of, or restrictions on, our limited partners or the limited partnership;

• brought in a derivative manner on behalf of the limited partnership;

• asserting a claim of breach of a duty owed by any director, officer, or other employee of the limited partnership or the general partner, or owed by the general partner, to the partnership or the limited partners;

• asserting a claim arising pursuant to any provision of the Delaware Revised Uniform Limited Partnership Act; or

• asserting a claim governed by the internal affairs doctrine.

The forum selection provision may restrict a limited partner's ability to bring a claim against us or directors, officers or other employee of ours or our general partner in a forum that it finds favorable, which may discourage limited partners from bringing such claims at all. Alternatively, if a court were to find the forum selection provision contained in our limited partnership agreement to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving such action in another forum, which could materially adversely affect our business, financial condition and results of operations. However, the forum selection provision does not apply to any claims, actions or proceedings arising under the Securities Act or the Exchange Act.

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

59

		Incorporated by Reference From
Exhibit Number	Exhibit Description	Form	Exhibit	Filing Date	SEC File No.	Filed Herewith	Furnished Herewith
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	Form of 2020 MPLX LP Phantom Unit Award Agreement - MPLX Officer					X
10.2	Form of 2020 MPLX LP Phantom Unit Award Agreement - MPC Officer					X
10.3	Form of 2020 MPLX LP Performance Unit Award Agreement 2020-2022 Performance Cycle - MPLX Officer					X
10.4	Form of MPLX LP Performance Unit Award Agreement 2020-2022 Performance Cycle - MPC Officer					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
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.

60

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: May 7, 2020	By:	/s/ C. Kristopher Hagedorn
		C. Kristopher Hagedorn
		Vice President and Controller of MPLX GP LLC (the general partner of MPLX LP)

61

EX-10.1

Exhibit 10.1

MPLX LP
2018 INCENTIVE COMPENSATION PLAN

PHANTOM UNIT AWARD AGREEMENT

MPLX OFFICER

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to [NAME] (the “Participant”), an officer of the Company, on [DATE] (the “Grant Date”), [NUMBER] Phantom Units, with each Phantom Unit representing the right to receive a Unit of the Partnership, subject to the terms and conditions in the Plan and this Award Agreement. The number of Phantom Units awarded is subject to adjustment as provided in the Plan, and the Phantom Units hereby granted are also subject to the following terms and conditions:

1.    Relationship to the Plan. This grant of Phantom Units is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan.

2.    Vesting and Forfeiture of Phantom Units.

(a)    Subject to paragraph 3, the Phantom Units shall vest in three cumulative annual installments, as follows:

(i) one-third of the Phantom Units shall vest on the first anniversary of the Grant Date;

(ii) an additional one-third of the Phantom Units shall vest on the second anniversary of the     Grant Date; and

(iii) all remaining Phantom Units shall vest on the third anniversary of the Grant Date;

provided, however, that the Participant must be in continuous Employment from the Grant Date through the applicable vesting date in order for the applicable Phantom Units to vest. If the Employment of the Participant is terminated for any reason (including non-Mandatory Retirement) other than one listed in subparagraph (b)(i) – (iii) of this Paragraph 2, any Phantom Units that have not vested as of the date of such termination of Employment shall be immediately and 100% forfeited to the Company.

(b)    Subject to paragraph 3, the Phantom Units shall immediately vest in full, irrespective of the limitations set forth in subparagraph (a) above, upon the occurrence of any of the following events, provided such termination of Participant’s Employment constitutes a separation from service (within the meaning of Section 409A of the Code):

1

(i) the Participant’s death;

(ii) the termination of the Participant’s Employment due to Mandatory Retirement; or

(iii) the Participant’s Qualified Termination, provided, that the Participant has been in continuous Employment from the Grant Date to the Qualified Termination.

3.Forfeiture of Phantom Unit if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Board may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Phantom Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as being accepted by the Participant.

4.    Distributions. During the period of time between the Grant Date and the date the Phantom Units are settled, for any distributions from the Partnership on outstanding Units of the Partnership, the Participant shall be credited with the equivalent of all of the distributions that would be payable with respect to the Unit of the Partnership represented by each Phantom Unit, including any fractional Phantom Units, then credited to the Participant and the amount related to such credited distributions shall be accrued as a credit to the Participant’s account on the date such distribution is made. Any additional cash or Phantom Units granted pursuant to this Paragraph 4 shall be subject to the same terms and conditions applicable to the Phantom Units to which these distributions relate, including, without limitation, the restrictions on transfer, forfeiture, settlement and distribution provisions contained in this Award Agreement or the Plan.

5.    Settlement and Issuance of Units. Subject to the terms of the Plan, all vested amounts payable to the Participant in respect of the Phantom Units, including the issuance of Units of the Partnership pursuant to this Paragraph 5, shall be settled in Units and for cash accruals credited under Paragraph 4 above, in cash, within 60 days following the vesting date. During the period of time between the Grant Date and the date the Phantom Units settle, the Phantom Units will be evidenced by a credit to a bookkeeping account evidencing the unfunded and unsecured right of the Participant to receive Units, subject to the terms and conditions applicable to the Phantom Units. Following vesting and upon the settlement date as described above, the Participant shall be entitled to receive a number of Units of the Partnership equal to the total of the number of Phantom Units granted, with any fractional Phantom Units remaining settled in cash. Such Units shall be issued and registered in the name of the Participant. The Participant shall not have the right or be entitled to exercise any voting rights, receive distributions or have or be entitled to any rights as a Partnership unitholder in respect of the Phantom Units until such time as the Phantom Units have vested and been settled and corresponding Units of the Partnership have been issued.

6.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the Units otherwise deliverable to the Participant due to the vesting of Phantom Units pursuant to Paragraph 2, or from other compensation payable to the Participant, at the time of the vesting and delivery of such Units. Because the Participant is an employee of Marathon Petroleum Corporation (“MPC”), and provides beneficial services to the Company through Participant’s Employment with MPC, MPC as the employer of Participant shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

2

7.    Conditions Precedent. This Paragraph 7 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Phantom Units under Paragraph 2, the Participant must satisfy the following conditions to and including the vesting date for each applicable annual installment or other applicable portion of the Award, and including any distribution right under the Award, under the vesting provisions in Paragraph 2:

(a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc, Chevron Corporation; ExxonMobil Corporation, HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Gas; Genesis Energy, L.P.; Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.; Western Gas Equity Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

(b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

(c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

(d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The

3

Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

(e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 7 (a), (b), (c) or (d), any unvested and unpaid portion of this Award at the time of such breach shall be forfeited, andthe rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

8.    Forfeiture or Repayment Resulting from Forfeiture Event.

(a)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause all of the Participant’s unvested Phantom Units to be forfeited by the Participant and returned to the Company.

(b)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then with respect to Phantom Units granted under this Award Agreement that have vested, the Board may, but is not obligated to, require that the Participant pay to the Company an amount (the “Forfeiture Amount”) up to (but not in excess of) the lesser of (i) the value of such previously vested Phantom Units as of the date such Phantom Units vested or (ii) the value of such previously vested Phantom Units as of the date on which the Board makes a demand for payment of the Forfeiture Amount. Any Forfeiture Amount shall be paid by the Participant within 60 days of receipt from the Company of written notice requiring payment of such Forfeiture Amount.

(c)    This Paragraph 8 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 8 shall not apply to the Participant following the effective time of a Change in Control.

(d)    Notwithstanding the any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Company any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the Units of the Partnership are listed for trading.

9.    Nonassignability. Upon the Participant’s death, the Phantom Units credited to the Participant under this Award Agreement shall be transferred to the Participant’s estate and upon such transfer settled in Units of the Partnership. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the Phantom Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Phantom Units shall have no effect.

4

10.    Nature of the Grant. Under this Award Agreement, the Participant is subject to condition that this Award of Phantom Units is voluntary and occasional and this Award Agreement does not create any contractual or other right to receive future Awards of Phantom Units, or benefits in lieu of Phantom Units even if Phantom Units have been awarded repeatedly in the past.

11.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any subsidiary or successor, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

12.    Modification of Instrument. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

13.Officer Holding Requirement. Participant agrees that any Units of the Partnership received by the Participant in settlement of this Award shall be subject an additional holding period of one year from the date on which the Award is settled, during which holding period such Units (net of any Units of the Partnership used to satisfy the applicable tax withholding requirements) may not be sold or transferred by the Participant. This holding requirement shall cease to apply upon the death, retirement or other separation from service of the Participant during the holding period.

14.Section 409A. This Award is intended to comply with or be exempt from the requirements of Section 409A of the Code. Notwithstanding the foregoing, if the Participant is a “specified employee” as determined by the Company in accordance with its established policy, any settlement of any amount in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s separation from service as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of the Phantom Units granted in this Award Agreement that would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code.

15.    Definitions. For purposes of this Award Agreement:

“Employment” means employment with the Company or any of its subsidiaries or Affiliates including but not limited to MPC and its subsidiaries and Affiliates. For purposes of this Award Agreement, Employment shall also include any period of time during which the Participant is on Disability status. The length of any period of Employment shall be determined by the Company or the subsidiary or Affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

5

“Forfeiture Event” means the occurrence of at least one of the following events: (a) the Company is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or an authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Company with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or (iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company.

“Mandatory Retirement” means termination of Employment as a result of the Company’s policy, if any, in effect at the time of the Grant Date, requiring the mandatory retirement of officers and/or other employees upon reaching a certain age or milestone.

“Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date, and such definition and associated terms are hereby incorporated into this Award Agreement by reference.

MPLX GP LLC
By
	Authorized Officer

6

EX-10.2

EXHIBIT 10.2

MPLX LP
2018 INCENTIVE COMPENSATION PLAN

PHANTOM UNIT AWARD AGREEMENT

MPC OFFICER

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to [NAME] (the “Participant”), an officer of Marathon Petroleum Corporation, the parent corporation of the Company (“MPC”) in connection with benefits conferred on the Company and the Partnership for their service as an officer of MPC, on [DATE] (the “Grant Date”), [NUMBER] Phantom Units, with each Phantom Unit representing the right to receive a Unit of the Partnership, subject to the terms and conditions in the Plan and this Award Agreement. The number of Phantom Units awarded is subject to adjustment as provided in the Plan, and the Phantom Units hereby granted are also subject to the following terms and conditions:

1.    Relationship to the Plan. This grant of Phantom Units is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan.

2.    Vesting and Forfeiture of Phantom Units.

(a)    Subject to paragraph 3, the Phantom Units shall vest in three cumulative annual installments, as follows:

(i) one-third of the Phantom Units shall vest on the first anniversary of the Grant Date;

(ii) an additional one-third of the Phantom Units shall vest on the second anniversary of the     Grant Date; and

(iii) all remaining Phantom Units shall vest on the third anniversary of the Grant Date;

provided, however, that the Participant must be in continuous Employment from the Grant Date through the applicable vesting date in order for the applicable Phantom Units to vest. If the Employment of the Participant is terminated for any reason (including non-Mandatory Retirement) other than one listed in subparagraph (b)(i) – (iii) of this Paragraph 2, any Phantom Units that have not vested as of the date of such termination of Employment shall be immediately and 100% forfeited to the Company.

(b)    Subject to paragraph 3, the Phantom Units shall immediately vest in full, irrespective of the limitations set forth in subparagraph (a) above, upon the occurrence of any of the following events, provided such termination of Participant’s Employment constitutes a separation from service (within the meaning of Section 409A of the Code):

1

(i) the Participant’s death;

(ii) the termination of the Participant’s Employment due to Mandatory Retirement; or

(iii) the Participant’s Qualified Termination, provided, that the Participant has been in continuous Employment from the Grant Date to the Qualified Termination.

3.     Forfeiture of Phantom Unit if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Board may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Phantom Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as being accepted by the Participant.

4.    Distributions. During the period of time between the Grant Date and the date the Phantom Units are settled, for any distributions from the Partnership on outstanding Units of the Partnership, the Participant shall be credited with the equivalent of all of the distributions that would be payable with respect to the Unit of the Partnership represented by each Phantom Unit, including any fractional Phantom Units, then credited to the Participant and the amount related to such credited distributions shall be accrued as a credit to the Participant’s account on the date such distribution is made. Any additional cash or Phantom Units granted pursuant to this Paragraph 4 shall be subject to the same terms and conditions applicable to the Phantom Units to which these distributions relate, including, without limitation, the restrictions on transfer, forfeiture, settlement and distribution provisions contained in this Award Agreement or the Plan.

5.    Settlement and Issuance of Units. Subject to the terms of the Plan, all vested amounts payable to the Participant in respect of the Phantom Units, including the issuance of Units of the Partnership pursuant to this Paragraph 5, shall be settled in Units and for cash accruals credited under Paragraph 4 above, in cash, within 60 days following the vesting date. During the period of time between the Grant Date and the date the Phantom Units settle, the Phantom Units will be evidenced by a credit to a bookkeeping account evidencing the unfunded and unsecured right of the Participant to receive Units, subject to the terms and conditions applicable to the Phantom Units. Following vesting and upon the settlement date as described above, the Participant shall be entitled to receive a number of Units of the Partnership equal to the total of the number of Phantom Units granted, with any fractional Phantom Units remaining settled in cash. Such Units shall be issued and registered in the name of the Participant. The Participant shall not have the right or be entitled to exercise any voting rights, receive distributions or have or be entitled to any rights as a Partnership unitholder in respect of the Phantom Units until such time as the Phantom Units have vested and been settled and corresponding Units of the Partnership have been issued.

6.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the Units otherwise deliverable to the Participant due to the vesting of Phantom Units pursuant to Paragraph 2, or from other compensation payable to the Participant, at the time of the vesting and delivery of such Units. Because the Participant is an employee of Marathon Petroleum Corporation (“MPC”), and provides beneficial services to the Company through Participant’s Employment with MPC, MPC as the employer of Participant shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

2

7.    Conditions Precedent. This Paragraph 7 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Phantom Units under Paragraph 2, the Participant must satisfy the following conditions to and including the vesting date for each applicable annual installment or other applicable portion of the Award, and including any distribution right under the Award, under the vesting provisions in Paragraph 2:

(a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc, Chevron Corporation; ExxonMobil Corporation, HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Gas; Genesis Energy, L.P.; Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.; Western Gas Equity Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

(b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

(c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

(d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain

3

members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

(e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 7 (a), (b), (c) or (d), any unvested and unpaid portion of this Award at the time of such breach shall be forfeited, andthe rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

8.    Forfeiture or Repayment Resulting from Forfeiture Event.

(a)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause all of the Participant’s unvested Phantom Units to be forfeited by the Participant and returned to the Company.

(b)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then with respect to Phantom Units granted under this Award Agreement that have vested, the Board may, but is not obligated to, require that the Participant pay to the Company an amount (the “Forfeiture Amount”) up to (but not in excess of) the lesser of (i) the value of such previously vested Phantom Units as of the date such Phantom Units vested or (ii) the value of such previously vested Phantom Units as of the date on which the Board makes a demand for payment of the Forfeiture Amount. Any Forfeiture Amount shall be paid by the Participant within 60 days of receipt from the Company of written notice requiring payment of such Forfeiture Amount.

(c)    This Paragraph 8 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 8 shall not apply to the Participant following the effective time of a Change in Control.

(d)    Notwithstanding the any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Company any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the Units of the Partnership are listed for trading.

9.    Nonassignability. Upon the Participant’s death, the Phantom Units credited to the Participant under this Award Agreement shall be transferred to the Participant’s estate and upon such transfer settled in Units of the Partnership. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the

4

Phantom Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Phantom Units shall have no effect.

10.    Nature of the Grant. Under this Award Agreement, the Participant is subject to condition that this Award of Phantom Units is voluntary and occasional and this Award Agreement does not create any contractual or other right to receive future Awards of Phantom Units, or benefits in lieu of Phantom Units even if Phantom Units have been awarded repeatedly in the past.

11.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any subsidiary or successor, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

12.    Modification of Instrument. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

13.Officer Holding Requirement. Participant agrees that any Units of the Partnership received by the Participant in settlement of this Award shall be subject an additional holding period of one year from the date on which the Award is settled, during which holding period such Units (net of any Units of the Partnership used to satisfy the applicable tax withholding requirements) may not be sold or transferred by the Participant. This holding requirement shall cease to apply upon the death, retirement or other separation from service of the Participant during the holding period.

14.Section 409A. This Award is intended to comply with or be exempt from the requirements of Section 409A of the Code. Notwithstanding the foregoing, if the Participant is a “specified employee” as determined by the Company in accordance with its established policy, any settlement of any amount in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s separation from service as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of the Phantom Units granted in this Award Agreement that would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code.

15.    Definitions. For purposes of this Award Agreement:

“Employment” means employment with the Company or any of its subsidiaries or Affiliates including but not limited to MPC and its subsidiaries and Affiliates. For purposes of this Award Agreement, Employment shall also include any period of time during which the Participant

5

is on Disability status. The length of any period of Employment shall be determined by the Company or the subsidiary or Affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

“Forfeiture Event” means the occurrence of at least one of the following events: (a) the Company is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or an authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Company with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or (iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company.

“Mandatory Retirement” means termination of Employment as a result of the Company’s policy, if any, in effect at the time of the Grant Date, requiring the mandatory retirement of officers and/or other employees upon reaching a certain age or milestone.

“Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date, and such definition and associated terms are hereby incorporated into this Award Agreement by reference.

MPLX GP LLC
By
	Authorized Officer

6

EX-10.3

Exhibit 10.3

MPLX LP
2018 INCENTIVE COMPENSATION PLAN

PERFORMANCE UNIT AWARD AGREEMENT

2020-2022 PERFORMANCE CYCLE

MPLX OFFICER

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to [NAME] (the “Participant”), an officer of the Company, on [DATE] (the “Grant Date”), [NUMBER] performance units (“Performance Units”), conditioned upon the Company’s total unitholder return (or “TUR”) ranking relative to the Peer Group and the DCF Payout Percentages for the Performance Cycle as established by the Board, and as set forth herein. The Performance Units are subject to the following terms and conditions:

1.    Relationship to the Plan. This grant of Performance Units is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as otherwise defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan. References to the Participant also include the heirs or other legal representatives of the Participant.

2.    Forfeiture of Performance Units if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Committee may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Performance Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as being accepted by the Participant.

3.    Determination of TUR Payout Percentage and DCF Payout Percentages; Calculation of Payout Value. As soon as administratively feasible following the close of the Performance Cycle, the Board shall determine and certify the TUR Payout Percentage and the DCF Payout Percentages (collectively, “the Payout Percentages”). The final Payout Value will be the sum of the TUR Payout Value and the DCF Payout Value, each as determined in accordance with this Paragraph 3.

    (a)    The “TUR Payout Percentage” is the simple average of the TUR Period Percentages for each of the following four performance periods:

(i) January 1, 2020 through December 31, 2020;

(ii) January 1, 2021 through December 31, 2021;

(iii) January 1, 2022 through December 31, 2022; and

(iv) January 1, 2020 through December 31, 2022.

1

The Board shall determine the TUR Period Percentage for each performance period as follows:

(I) First, the Board shall determine the TUR Performance Percentile, and then the TUR Period Percentage as follows (using straight-line interpolation between threshold level (30^th percentile) and target level (50^th percentile) and between target level and maximum (100^th percentile)):

TUR Performance Percentile	TUR Period Percentage
Ranked below 30th percentile	0%
Ranked at 30th percentile	50%
Ranked at 50th percentile	100%
Ranked at the 100th percentile	200%

(II) Notwithstanding anything herein to the contrary, if the Partnership’s Total Unitholder Return calculated for the applicable performance period is negative, then the TUR Period Percentage for that performance period will not exceed 100% regardless of the TUR Performance Percentile for the performance period.

(III) Notwithstanding anything herein to the contrary, the Board has sole and absolute authority and discretion to reduce the TUR Payout Percentage as it may deem appropriate.

(b)    The “TUR Payout Value” for each Performance Unit is the product of the TUR Payout Percentage and $0.50.

(c)    A DCF Payout Percentage will be determined for each of the following three performance periods:

(i) January 1, 2020 through December 31, 2020;

(ii) January 1, 2021 through December 31, 2021; and

(iii) January 1, 2022 through December 31, 2022.

The Board shall determine the DCF Payout Percentage for each performance period based upon the Partnership’s DCF Per Common Unit for such performance period (each a “DCF Measurement Period”) as follows (using straight-line interpolation between levels above threshold):

DCF Per Common Unit	DCF Payout Percentage
Below Threshold	0%
Threshold	50%
Target	100%
Maximum	200%

The threshold, target and maximum performance levels for each DCF Measurement Period will be those certain levels that are established by the Board for purposes of this Award, which level shall be set forth in a confidential memorandum or other

2

written communication provided to the Participant, as such levels may be adjusted pursuant to the provisions of the Plan, as applicable. The confidential memorandum or other written communication containing the threshold, target and maximum performance levels for the first DCF Measurement Period is being provided to the Participant on or around the Grant Date and the confidential memorandum or other written communication containing the threshold, target and maximum performance levels for subsequent DCF Measurement Periods will be provided to the Participant following the determination of such levels by the Board at or near the beginning of such periods.

(d)    The “DCF Payout Value” for each Performance Unit will be the sum of:

(i)     the product of the DCF Payout Percentage for first performance period and $0.167;

(ii)    the product of the DCF Payout Percentage for second performance period and $0.167; and

(iii)    the product of the DCF Payout Percentage for the third performance period and $0.166.

Notwithstanding anything herein to the contrary, the Board has sole and absolute authority and discretion to reduce some or all of the DCF Payout Percentages as it may deem appropriate.

4.    Vesting and Payment of Performance Units; Payment Amount; Time and Form of Payment. Unless the Participant’s right to the Performance Units is previously forfeited or vested in accordance with Paragraphs 5, 6, 7, 8 or 9, the Participant shall vest in the Performance Units on December 31, 2021, provided the Participant has not terminated Employment on or before that date. The Participant will be entitled to an amount equal to the product of the vested number of Performance Units and the Payout Value, and such amount shall be distributed 75% in cash and 25% in common units.  The number of common units distributed shall be calculated by dividing 25% of the total amount payable by the Fair Market Value of the common units on the date on which the Payout Percentages are certified by the Board, rounding down to the nearest whole unit.  The remainder shall be paid in cash.  Such payments shall be made as soon as administratively feasible following the Board’s determinations under Paragraph 3 and, in any event, between January 1 and March 15^th immediately following the end of the Performance Cycle. If, in accordance with the Board’s determination under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 4 and the making of the related payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full.

5.    Termination of Employment. If the Participant’s Employment is terminated prior to the close of the Performance Cycle for any reason other than death, Retirement, Qualified Termination, or Mandatory Retirement, as set forth in Paragraphs 6, 7, 8 and 9 below, the Participant’s Performance Units shall be settled based on the performance for the Performance Cycle and shall vest and be payable on a pro-rata basis as follows, and in each case subject to the negative discretion of the Board:

(a)    If the Participant’s Employment is terminated prior to January 1, 2021, the Participant’s right to the Performance Units shall be forfeited in its entirety as of the date of such termination, and the rights of the Participant and the obligations of the Company under this Award Agreement shall be terminated;

(b)    If the Participant’s Employment is terminated during the period January 1, 2021 and December 31, 2021, the Participant will be entitled to receive a payment equal to the product of (i) one-third the number of Performance Units and (ii) the Payout Value;

3

(c)    If the Participant’s Employment is terminated during the period January 1, 2022 and December 31, 2022, the Participant will be entitled to receive a payment equal to the product of (i) two-thirds the number of Performance Units and (ii) the Payout Value.

Payment of such vested value of Performance Units under subparagraphs (b) or (c) of this Paragraph 5, as applicable, shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 5 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 5.

6.    Termination of Employment due to Death. If the Participant’s Employment is terminated by reason of death prior to the close of the Performance Cycle, the Participant’s right to receive the Performance Units shall vest in full as of the date of death and the Payout Value shall be determined as if the Payout Percentages are each 100%. The payment on the vested Performance Units shall be made in accordance with Paragraph 4 as soon as administratively feasible but in all cases no later than the last day of the calendar year following the calendar year in which the Participant’s death occurs; provided, however, that the timing of the payment shall be determined in the sole discretion of the Board and no other individual or entity shall directly or indirectly designate the taxable year of payment. Such vesting shall satisfy the rights of the Participant and the obligations of the Company under this Award Agreement in full.

7.    Termination of Employment due to Retirement. In the event of the Retirement of the Participant after nine months of the Performance Cycle have elapsed, the Participant’s Performance Units shall be settled based on the performance for the Performance Cycle and shall vest and be payable on a pro-rata basis as determined and certified by the Board after the close of the Performance Cycle as described below. Subject to the negative discretion of the Board, the Participant will be entitled to receive a payment equal to the product of (i) the pro-rata vesting percentage equal to the days of the Participant’s Employment during the Performance Cycle divided by the total days in the Performance Cycle and (ii) the Payout Value. Payment of such vested value of Performance Units under this Paragraph 7 shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 7 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 7.

8.Vesting Upon a Qualified Termination. Notwithstanding anything herein to the contrary, upon the Participant’s Qualified Termination prior to the end of the Performance Cycle, the Participant’s right to receive the Performance Units, unless previously forfeited pursuant to Paragraph 5, shall vest in full. The TUR Payout Percentage shall be determined as follows (subject to the negative discretion of the Board): (i) for the time period from the beginning of the Performance Cycle to the date of the Change in Control (as defined in the Marathon Petroleum Corporation Amended and Restated Executive Change in Control Severance Benefits Plan), based upon actual TUR Performance Percentile and (ii) for the time period from the date of the Change in Control to the end of the Performance Cycle, the TUR Payout Percentage shall be 100%. The DCF Payout Percentages shall be determined as follows (subject to the negative discretion of the Board): (i) for the time period from the beginning of the Performance Cycle to the date of the Change in Control (as defined in the Marathon Petroleum Corporation Amended and Restated Executive Change in Control Severance Benefits Plan), based upon actual DCF Payout

4

Percentages and (ii) for the time period from the date of the Change in Control to the end of the Performance Cycle, the DCF Payout Percentages shall be 100%. A payment equal to the vested value of the Performance Units shall be made in accordance with Paragraph 4, except that it shall be made 100% in cash.

9.    Termination of Employment due to Mandatory Retirement. In the event the Participant’s Employment is terminated as a result of Mandatory Retirement prior to the end of the Performance Cycle, the Participant’s right to receive the Performance Units shall vest in full, and such vested and shall be settled based on the Payout Value determined under Paragraph 3. Payment of such vested value of Performance Units under this Paragraph 9 shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 9 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Mandatory Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 9.

10.    Specified Employee. Notwithstanding any other provision of this Award Agreement to the contrary, if the Participant is a “specified employee” within the meaning of Section 409A of the Code as determined by the Company in accordance with its established policy, any settlement of any amount described in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s “separation from service” as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of this Award which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code.

11.    Conditions Precedent. This Paragraph 11 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Performance Units under Paragraph 4, the Participant must satisfy the following conditions to and including the vesting date for each applicable annual installment or other applicable portion of the Award, under the vesting provisions in Paragraph 4:

(a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc, Chevron Corporation; ExxonMobil Corporation, HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Gas; Genesis Energy, L.P.; Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.;

5

Western Gas Equity Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

(b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

(c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

(d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

(e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 11(a), (b), (c) or (d), any unvested and unpaid portion of this Award at the time of such breach shall be forfeited, andthe rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

12.    Repayment or Forfeiture Resulting from Forfeiture Event.

6

(a)    If there is a Forfeiture Event either during the Participant’s Employment or within three years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause some or all of the Participant’s outstanding Performance Units to be forfeited by the Participant.

(b)    If there is a Forfeiture Event either during the Participant’s Employment or within three years after termination of the Participant’s Employment and a payment has previously been made in settlement of Performance Units granted under this Award Agreement, the Board may, but is not obligated to, require that the Participant pay to the Company an amount in cash (the “Forfeiture Amount”) up to (but not in excess of) the amount paid in settlement of the Performance Units.

(c)     This Paragraph 12 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 12 shall not apply to the Participant following the effective time of a Change in Control.

(d)    Notwithstanding the foregoing or any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Company any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the common units of the Partnership are listed for trading.

13.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the common units and cash amount otherwise payable to the Participant due to the vesting of Performance Units pursuant to Paragraph 4, or from other compensation payable to the Participant (to the extent consistent with Section 409A of the Code), at the time of the vesting of the Performance Units and delivery of the cash settlement amount. Because the Participant is an employee of MPC, and provides beneficial services to the Company through Participant’s employment with MPC, MPC as the employer of Participant, shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

14.    No Unitholder Rights. The Participant shall in no way be entitled to any of the rights of a unitholder as a result of this Award Agreement.

15.    Nonassignability. Upon the Participant’s death, the Performance Units may be transferred by will or by the laws governing the descent and distribution of the Participant’s estate. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the Performance Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Performance Units shall have no effect.

16.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any affiliate thereof or successor thereto, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

17.    Modification of Agreement. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

7

18.    Officer Holding Requirement. Participant agrees that any common units received by the Participant in settlement of this Award shall be subject an additional holding period of one year from the date on which the Award is settled, during which holding period such common units (net of any common units used to satisfy the applicable tax withholding requirements) may not be sold or transferred by the Participant. This holding requirement shall cease to apply upon the death, retirement or other separation from service of the Participant during the holding period.

19.    Definitions. For purposes of this Award Agreement:

“Beginning Unit Price”means the average of the daily closing price of a common unit of the Partnership for the 20 trading days immediately prior to the commencement of the Performance Cycle, historically adjusted, if necessary, for any split, dividend, recapitalizations, or similar corporate events that occur during the measurement period.

“DCF Per Common Unit”for an applicable DCF Measurement Period means the quotient obtained by dividing (A) the Partnership’s distributable cash flow available to general and limited partners (as reported in the Partnership’s financial statements) for such DCF Measurement Period less all such amounts attributable to the general partner interest and the incentive distribution rights in the Partnership, by (B) the weighted average number of common units in the Partnership outstanding during such DCF Measurement Period.

“Employment” means employment with the Company or any of its subsidiaries or affiliates including but not limited to MPC and its subsidiaries and affiliates. For purposes of this Award Agreement, Employment shall also include any period of time during which the Participant is on Disability status. The length of any period of Employment shall be determined by the Company or the Subsidiary or affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

“End Unit Price”means the average of the daily closing price of a common unit of the Partnership for the 20 trading days prior to the end of the Performance Cycle.

“Forfeiture Event” means the occurrence of at least one of the following events: (a) the Company is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or any authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Company with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or (iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company.

“Mandatory Retirement” means, as determined by the Board of Directors of MPC, the mandatory retirement age of 65 for Participants who are in bona fide executive or in high policymaking positions and in Grades 19 and above if: (1) the Participant has been employed in such capacity for the two-year period immediately prior to mandatory retirement; and (2) the Participant is entitled to the minimum retirement benefit specified by federal law for persons who hold positions to which mandatory retirement may lawfully

8

apply. Mandatory Retirement is required by the earlier of the first of the month coincident with or immediately following the Participant’s 65^th birthday.

“Peer Group” means the group of companies that are pre-established by the Board which principally represent a group of selected peers, or such other group of companies as selected and pre-established by the Board. For this Award, the Board has determined that the Peer Group for each applicable measurement period will be the ten companies in the Alerian MLP Index with the highest market capitalization as determined on the last day of the measurement period.

“Performance Cycle”means the period from January 1, 2020 to December 31, 2022.

“Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date (disregarding subsection II of such definition) (the “CIC Plan”), and such definition and associated terms are hereby incorporated into this Award Agreement by reference. Notwithstanding the definition of a “Change in Control” under the terms of the CIC Plan, for purposes of this Award Agreement such Change in Control for purposes of determining whether a separation from service is a Qualified Termination shall include a Change in Control of either MPC, as the direct employer of the Participant, or a Change in Control of the Partnership, as the issuer of the Award.

“Retirement”means (a) for a Participant with ten or more years of Employment, termination on or after the Participant’s 50th birthday, or (b) termination on or after the Participant’s 65th birthday.

“Total Unitholder Return” or “TUR” means for the Company and each entity in the Peer Group the number derived using the following formula:

(End Unit Price – Beginning Unit Price) + Cumulative Cash Distributions

Beginning Unit Price.

“TUR Performance Percentile” means the percentile ranking of the Company’s Total Unitholder Return for a performance period among the Total Unitholder Returns of the Peer Group companies, ranked in descending order, for the performance period as determined at the end of the Performance Cycle.

MPLX GP LLC
By
	Authorized Officer

9

EX-10.4

EXHIBIT 10.4

MPLX LP
2018 INCENTIVE COMPENSATION PLAN

PERFORMANCE UNIT AWARD AGREEMENT

2020-2022 PERFORMANCE CYCLE

MPC OFFICER

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to [NAME] (the “Participant”), an officer of Marathon Petroleum Corporation, the parent corporation of the Company (“MPC”) in connection with benefits conferred on the Company and the Partnership for their service as an officer of MPC, on [DATE] (the “Grant Date”), [NUMBER] performance units (“Performance Units”), conditioned upon the Company’s total unitholder return (or “TUR”) ranking relative to the Peer Group and the DCF Payout Percentages for the Performance Cycle as established by the Board, and as set forth herein. The Performance Units are subject to the following terms and conditions:

1.    Relationship to the Plan. This grant of Performance Units is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as otherwise defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan. References to the Participant also include the heirs or other legal representatives of the Participant.

2.    Forfeiture of Performance Units if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Committee may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Performance Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as being accepted by the Participant.

3.    Determination of TUR Payout Percentage and DCF Payout Percentages; Calculation of Payout Value. As soon as administratively feasible following the close of the Performance Cycle, the Board shall determine and certify the TUR Payout Percentage and the DCF Payout Percentages (collectively, “the Payout Percentages”). The final Payout Value will be the sum of the TUR Payout Value and the DCF Payout Value, each as determined in accordance with this Paragraph 3.

    (a)    The “TUR Payout Percentage” is the simple average of the TUR Period Percentages for each of the following four performance periods:

(i) January 1, 2020 through December 31, 2020;

(ii) January 1, 2021 through December 31, 2021;

(iii) January 1, 2022 through December 31, 2022; and

1

(iv) January 1, 2020 through December 31, 2022.

The Board shall determine the TUR Period Percentage for each performance period as follows:

(I) First, the Board shall determine the TUR Performance Percentile, and then the TUR Period Percentage as follows (using straight-line interpolation between threshold level (30^th percentile) and target level (50^th percentile) and between target level and maximum (100^th percentile)):

TUR Performance Percentile	TUR Period Percentage
Ranked below 30th percentile	0%
Ranked at 30th percentile	50%
Ranked at 50th percentile	100%
Ranked at the 100th percentile	200%

(II) Notwithstanding anything herein to the contrary, if the Partnership’s Total Unitholder Return calculated for the applicable performance period is negative, then the TUR Period Percentage for that performance period will not exceed 100% regardless of the TUR Performance Percentile for the performance period.

(III) Notwithstanding anything herein to the contrary, the Board has sole and absolute authority and discretion to reduce the TUR Payout Percentage as it may deem appropriate.

(b)    The “TUR Payout Value” for each Performance Unit is the product of the TUR Payout Percentage and $0.50.

(c)    A DCF Payout Percentage will be determined for each of the following three performance periods:

(i) January 1, 2020 through December 31, 2020;

(ii) January 1, 2021 through December 31, 2021; and

(iii) January 1, 2022 through December 31, 2022.

The Board shall determine the DCF Payout Percentage for each performance period based upon the Partnership’s DCF Per Common Unit for such performance period (each a “DCF Measurement Period”) as follows (using straight-line interpolation between levels above threshold):

DCF Per Common Unit	DCF Payout Percentage
Below Threshold	0%
Threshold	50%
Target	100%
Maximum	200%

2

The threshold, target and maximum performance levels for each DCF Measurement Period will be those certain levels that are established by the Board for purposes of this Award, which level shall be set forth in a confidential memorandum or other written communication provided to the Participant, as such levels may be adjusted pursuant to the provisions of the Plan, as applicable. The confidential memorandum or other written communication containing the threshold, target and maximum performance levels for the first DCF Measurement Period is being provided to the Participant on or around the Grant Date and the confidential memorandum or other written communication containing the threshold, target and maximum performance levels for subsequent DCF Measurement Periods will be provided to the Participant following the determination of such levels by the Board at or near the beginning of such periods.

(d)    The “DCF Payout Value” for each Performance Unit will be the sum of:

(i) the product of the DCF Payout Percentage for first performance period and $0.167;

(ii) the product of the DCF Payout Percentage for second performance period and $0.167; and

(iii) the product of the DCF Payout Percentage for the third performance period and $0.166.

Notwithstanding anything herein to the contrary, the Board has sole and absolute authority and discretion to reduce some or all of the DCF Payout Percentages as it may deem appropriate.

4.    Vesting and Payment of Performance Units; Payment Amount; Time and Form of Payment. Unless the Participant’s right to the Performance Units is previously forfeited or vested in accordance with Paragraphs 5, 6, 7, 8 or 9, the Participant shall vest in the Performance Units on December 31, 2021, provided the Participant has not terminated Employment on or before that date. The Participant will be entitled to an amount equal to the product of the vested number of Performance Units and the Payout Value, and such amount shall be distributed 75% in cash and 25% in common units.  The number of common units distributed shall be calculated by dividing 25% of the total amount payable by the Fair Market Value of the common units on the date on which the Payout Percentages are certified by the Board, rounding down to the nearest whole unit.  The remainder shall be paid in cash.  Such payments shall be made as soon as administratively feasible following the Board’s determinations under Paragraph 3 and, in any event, between January 1 and March 15^th immediately following the end of the Performance Cycle. If, in accordance with the Board’s determination under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 4 and the making of the related payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full.

5.    Termination of Employment. If the Participant’s Employment is terminated prior to the close of the Performance Cycle for any reason other than death, Retirement, Qualified Termination, or Mandatory Retirement, as set forth in Paragraphs 6, 7, 8 and 9 below, the Participant’s Performance Units shall be settled based on the performance for the Performance Cycle and shall vest and be payable on a pro-rata basis as follows, and in each case subject to the negative discretion of the Board:

(a)    If the Participant’s Employment is terminated prior to January 1, 2021, the Participant’s right to the Performance Units shall be forfeited in its entirety as of the date of such termination, and the rights of the Participant and the obligations of the Company under this Award Agreement shall be terminated;

3

(b)    If the Participant’s Employment is terminated during the period January 1, 2021 and December 31, 2021, the Participant will be entitled to receive a payment equal to the product of (i) one-third the number of Performance Units and (ii) the Payout Value;

(c)    If the Participant’s Employment is terminated during the period January 1, 2022 and December 31, 2022, the Participant will be entitled to receive a payment equal to the product of (i) two-thirds the number of Performance Units and (ii) the Payout Value.

Payment of such vested value of Performance Units under subparagraphs (b) or (c) of this Paragraph 5, as applicable, shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 5 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 5.

6.    Termination of Employment due to Death. If the Participant’s Employment is terminated by reason of death prior to the close of the Performance Cycle, the Participant’s right to receive the Performance Units shall vest in full as of the date of death and the Payout Value shall be determined as if the Payout Percentages are each 100%. The payment on the vested Performance Units shall be made in accordance with Paragraph 4 as soon as administratively feasible but in all cases no later than the last day of the calendar year following the calendar year in which the Participant’s death occurs; provided, however, that the timing of the payment shall be determined in the sole discretion of the Board and no other individual or entity shall directly or indirectly designate the taxable year of payment. Such vesting shall satisfy the rights of the Participant and the obligations of the Company under this Award Agreement in full.

7.    Termination of Employment due to Retirement. In the event of the Retirement of the Participant after nine months of the Performance Cycle have elapsed, the Participant’s Performance Units shall be settled based on the performance for the Performance Cycle and shall vest and be payable on a pro-rata basis as determined and certified by the Board after the close of the Performance Cycle as described below. Subject to the negative discretion of the Board, the Participant will be entitled to receive a payment equal to the product of (i) the pro-rata vesting percentage equal to the days of the Participant’s Employment during the Performance Cycle divided by the total days in the Performance Cycle and (ii) the Payout Value. Payment of such vested value of Performance Units under this Paragraph 7 shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 7 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 7.

8.Vesting Upon a Qualified Termination. Notwithstanding anything herein to the contrary, upon the Participant’s Qualified Termination prior to the end of the Performance Cycle, the Participant’s right to receive the Performance Units, unless previously forfeited pursuant to Paragraph 5, shall vest in full. The TUR Payout Percentage shall be determined as follows (subject to the negative discretion of the Board): (i) for the time period from the beginning of the Performance Cycle to the date of the Change in Control (as defined in the Marathon Petroleum Corporation Amended and Restated Executive Change in Control Severance Benefits Plan), based upon actual TUR Performance Percentile and (ii) for the time period from the date of the Change in Control to the end of the Performance Cycle, the TUR Payout Percentage shall be 100%. The DCF Payout Percentages shall be determined as follows (subject to the negative discretion of the Board): (i) for the time period

4

from the beginning of the Performance Cycle to the date of the Change in Control (as defined in the Marathon Petroleum Corporation Amended and Restated Executive Change in Control Severance Benefits Plan), based upon actual DCF Payout Percentages and (ii) for the time period from the date of the Change in Control to the end of the Performance Cycle, the DCF Payout Percentages shall be 100%. A payment equal to the vested value of the Performance Units shall be made in accordance with Paragraph 4, except that it shall be made 100% in cash.

9.    Termination of Employment due to Mandatory Retirement. In the event the Participant’s Employment is terminated as a result of Mandatory Retirement prior to the end of the Performance Cycle, the Participant’s right to receive the Performance Units shall vest in full, and such vested and shall be settled based on the Payout Value determined under Paragraph 3. Payment of such vested value of Performance Units under this Paragraph 9 shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 9 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Mandatory Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 9.

10.    Specified Employee. Notwithstanding any other provision of this Award Agreement to the contrary, if the Participant is a “specified employee” within the meaning of Section 409A of the Code as determined by the Company in accordance with its established policy, any settlement of any amount described in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s “separation from service” as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of this Award which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code.

11.    Conditions Precedent. This Paragraph 11 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Performance Units under Paragraph 4, the Participant must satisfy the following conditions to and including the vesting date for each applicable annual installment or other applicable portion of the Award, under the vesting provisions in Paragraph 4:

(a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc, Chevron Corporation; ExxonMobil Corporation, HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Gas; Genesis Energy, L.P.;

5

Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.; Western Gas Equity Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

(b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

(c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

(d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

(e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 11(a), (b), (c) or (d), any unvested and unpaid portion of this Award at the time of such breach shall be forfeited, andthe rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

6

12.    Repayment or Forfeiture Resulting from Forfeiture Event.

(a)    If there is a Forfeiture Event either during the Participant’s Employment or within three years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause some or all of the Participant’s outstanding Performance Units to be forfeited by the Participant.

(b)    If there is a Forfeiture Event either during the Participant’s Employment or within three years after termination of the Participant’s Employment and a payment has previously been made in settlement of Performance Units granted under this Award Agreement, the Board may, but is not obligated to, require that the Participant pay to the Company an amount in cash (the “Forfeiture Amount”) up to (but not in excess of) the amount paid in settlement of the Performance Units.

(c)     This Paragraph 12 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 12 shall not apply to the Participant following the effective time of a Change in Control.

(d)    Notwithstanding the foregoing or any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Company any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the common units of the Partnership are listed for trading.

13.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the common units and cash amount otherwise payable to the Participant due to the vesting of Performance Units pursuant to Paragraph 4, or from other compensation payable to the Participant (to the extent consistent with Section 409A of the Code), at the time of the vesting of the Performance Units and delivery of the cash settlement amount. Because the Participant is an employee of MPC, and provides beneficial services to the Company through Participant’s employment with MPC, MPC as the employer of Participant, shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

14.    No Unitholder Rights. The Participant shall in no way be entitled to any of the rights of a unitholder as a result of this Award Agreement.

15.    Nonassignability. Upon the Participant’s death, the Performance Units may be transferred by will or by the laws governing the descent and distribution of the Participant’s estate. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the Performance Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Performance Units shall have no effect.

16.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any affiliate thereof or successor thereto, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

17.    Modification of Agreement. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

7

18.    Officer Holding Requirement. Participant agrees that any common units received by the Participant in settlement of this Award shall be subject an additional holding period of one year from the date on which the Award is settled, during which holding period such common units (net of any common units used to satisfy the applicable tax withholding requirements) may not be sold or transferred by the Participant. This holding requirement shall cease to apply upon the death, retirement or other separation from service of the Participant during the holding period.

19.    Definitions. For purposes of this Award Agreement:

“Beginning Unit Price”means the average of the daily closing price of a common unit of the Partnership for the 20 trading days immediately prior to the commencement of the Performance Cycle, historically adjusted, if necessary, for any split, dividend, recapitalizations, or similar corporate events that occur during the measurement period.

“DCF Per Common Unit”for an applicable DCF Measurement Period means the quotient obtained by dividing (A) the Partnership’s distributable cash flow available to general and limited partners (as reported in the Partnership’s financial statements) for such DCF Measurement Period less all such amounts attributable to the general partner interest and the incentive distribution rights in the Partnership, by (B) the weighted average number of common units in the Partnership outstanding during such DCF Measurement Period.

“Employment” means employment with the Company or any of its subsidiaries or affiliates including but not limited to MPC and its subsidiaries and affiliates. For purposes of this Award Agreement, Employment shall also include any period of time during which the Participant is on Disability status. The length of any period of Employment shall be determined by the Company or the Subsidiary or affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

“End Unit Price”means the average of the daily closing price of a common unit of the Partnership for the 20 trading days prior to the end of the Performance Cycle.

“Forfeiture Event” means the occurrence of at least one of the following events: (a) the Company is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or any authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Company with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or (iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company.

“Mandatory Retirement” means, as determined by the Board of Directors of MPC, the mandatory retirement age of 65 for Participants who are in bona fide executive or in high policymaking positions and in Grades 19 and above if: (1) the Participant has been employed in such capacity for the two-year period immediately prior to mandatory retirement; and (2) the Participant is entitled to the minimum retirement benefit specified by federal law for persons who hold positions to which mandatory retirement may lawfully

8

apply. Mandatory Retirement is required by the earlier of the first of the month coincident with or immediately following the Participant’s 65^th birthday.

“Peer Group” means the group of companies that are pre-established by the Board which principally represent a group of selected peers, or such other group of companies as selected and pre-established by the Board. For this Award, the Board has determined that the Peer Group for each applicable measurement period will be the ten companies in the Alerian MLP Index with the highest market capitalization as determined on the last day of the measurement period.

“Performance Cycle”means the period from January 1, 2020 to December 31, 2022.

“Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date (disregarding subsection II of such definition) (the “CIC Plan”), and such definition and associated terms are hereby incorporated into this Award Agreement by reference. Notwithstanding the definition of a “Change in Control” under the terms of the CIC Plan, for purposes of this Award Agreement such Change in Control for purposes of determining whether a separation from service is a Qualified Termination shall include a Change in Control of either MPC, as the direct employer of the Participant, or a Change in Control of the Partnership, as the issuer of the Award.

“Retirement”means (a) for a Participant with ten or more years of Employment, termination on or after the Participant’s 50th birthday, or (b) termination on or after the Participant’s 65th birthday.

“Total Unitholder Return” or “TUR” means for the Company and each entity in the Peer Group the number derived using the following formula:

(End Unit Price – Beginning Unit Price) + Cumulative Cash Distributions

Beginning Unit Price.

“TUR Performance Percentile” means the percentile ranking of the Company’s Total Unitholder Return for a performance period among the Total Unitholder Returns of the Peer Group companies, ranked in descending order, for the performance period as determined at the end of the Performance Cycle.

MPLX GP LLC
By
	Authorized Officer

9

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: May 7, 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: May 7, 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 March 31, 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: May 7, 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 March 31, 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: May 7, 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

Equity Method Investments (Tables)

3 Months Ended

Mar. 31, 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
	March 31,	March 31,		December 31,
(In millions, except ownership percentages)	2020	2020		2019
L&S
MarEn Bakken Company LLC	25%	$	479	$	481
Illinois Extension Pipeline Company, L.L.C.	35%	271		265
LOOP LLC	41%	239		238
Andeavor Logistics Rio Pipeline LLC(1)	67%	200		202
Minnesota Pipe Line Company, LLC	17%	190		190
Whistler Pipeline LLC(1)	38%	163		134
W2W Holdings LLC(1)(2)	50%	76		—
Wink to Webster Pipeline LLC(1)(2)	15%	—		126
Explorer Pipeline Company	25%	81		83
Other(1)		55		55
Total L&S		1,754		1,774
G&P
MarkWest Utica EMG, L.L.C.(1)	57%	712		1,984
Sherwood Midstream LLC(1)	50%	546		537
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(1)	67%	302		302
Rendezvous Gas Services, L.L.C.(1)	78%	167		170
Sherwood Midstream Holdings LLC(1)	52%	155		157
Centrahoma Processing LLC	40%	150		153
Other(1)		206		198
Total G&P		2,238		3,501
Total		$	3,992	$	5,275

(1) Investments deemed to be VIE’s. Some investments included within “Other” have also been deemed to be VIE’s.

(2) During the three months ended March 31, 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 three months ended March 31, 2020 and 2019 is as follows:

	Three Months Ended March 31, 2020
(In millions)	VIEs			Non-VIEs		Total
Revenues and other income	$	(217	)	$	337	$	120
Costs and expenses	104			132		236
Income from operations	(321		)	205		(116		)
Net income	(337		)	186		(151		)
(Loss)/income from equity method investments(1)	$	(1,222	)	$	38	$	(1,184	)

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

	Three Months Ended March 31, 2019(1)
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	155	$	391	$	546
Costs and expenses	77		198		275
Income from operations	78		193		271
Net income	71		181		252
Income from equity method investments	$	27	$	50	$	77

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

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

	March 31, 2020
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	320	$	325	$	645
Noncurrent assets	5,384		5,115		10,499
Current liabilities	153		195		348
Noncurrent liabilities	$	544	$	859	$	1,403

	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

XML

Series A Preferred Units (Tables)

3 Months Ended

Mar. 31, 2020

Temporary Equity Disclosure [Abstract]

Rollforward of Redeemable Preferred Units

The changes in the redeemable preferred balance from December 31, 2019 through March 31, 2020 are summarized below:

(In millions)	Redeemable Series A Preferred Units
Balance at December 31, 2019	$	968
Net income allocated	20
Distributions received by Series A preferred unitholders	(20		)
Balance at March 31, 2020	$	968

XML

Equity

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Equity

Equity

The changes in the number of common units outstanding during the three months ended March 31, 2020 are summarized below:

(In units)	Common
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	151,878
Balance at March 31, 2020	1,058,507,349

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 March 31, 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	11
Distributions received by Series B preferred unitholders	(21		)
Balance at March 31, 2020	$	601

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 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. No distributions were earned by the TexNew Mex units in the first quarter of 2020.

Cash distributions – In accordance with the MPLX partnership agreement, on April 28, 2020, MPLX declared a quarterly cash distribution for the first quarter of 2020, totaling $728 million, or $0.6875 per common unit. This rate will also be received by Series A preferred unitholders. These distributions will be paid on May 15, 2020 to common unitholders of record on May 8, 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. MPLX made a cash distribution to holders of the Series B preferred unitholders in February 2020 for approximately $21 million.

Quarterly distributions for the first quarter of 2020 and 2019 are summarized below:

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

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three months ended March 31, 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 March 31,
(In millions)	2020		2019(1)
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	728	$	523
Series A preferred unit distributions	20		20
Series B preferred unit distributions	11		—
Total cash distributions declared	$	759	$	543

(1)

The distribution on common units for the three months ended March 31, 2019 does not include the impact of the issuance of units in connection with the merger.

XML

Acquisitions

3 Months Ended

Mar. 31, 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. (“Southwest, Inc.”), 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 $1 million in acquisition costs during the first quarter of 2019 related to the Merger, which are reflected in general and administrative expenses. For the three months ended March 31, 2019, we recognized $589 million of revenues and other income and $180 million of net income related to ANDX.

XML

Property, Plant and Equipment

3 Months Ended

Mar. 31, 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	March 31, 2020		December 31, 2019
L&S
Pipelines	2-51 years	$	5,637	$	5,572
Refining Logistics	13-40 years	2,308		2,870
Terminals	2-40 years	1,176		1,109
Marine	15-20 years	960		906
Land, building and other	1-61 years	1,827		1,817
Construction-in progress		618		660
Total L&S property, plant and equipment		12,526		12,934
G&P
Gathering and transportation	5-40 years	7,349		7,159
Processing and fractionation	15-40 years	5,605		5,545
Land, building and other	3-40 years	491		484
Construction-in-progress		616		745
Total G&P property, plant and equipment		14,061		13,933
Total property, plant and equipment		26,587		26,867
Less accumulated depreciation(1)		4,758		4,722
Property, plant and equipment, net		$	21,829	$	22,145

(1) The March 31, 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.

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. 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. 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.

XML

Derivatives Financial Instruments - Derivative Income Statement Location (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Derivative [Line Items]
Total gain (loss)		$ 14	$ (6)
Product sales
Derivative [Line Items]
Realized gain (loss)		0	0
Total gain (loss)		0	0
Purchased product costs
Derivative [Line Items]
Realized gain (loss)		(1)	(2)
Total gain (loss)		14	(6)
Cost of revenues
Derivative [Line Items]
Realized gain (loss)		0	0
Total gain (loss)		0	0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	[1]	15	(4)	[2]
Not Designated as Hedging Instrument [Member] | Product sales
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts		0	0
Not Designated as Hedging Instrument [Member] | Purchased product costs
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts		15	(4)
Not Designated as Hedging Instrument [Member] | Cost of revenues
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts		$ 0	$ 0

[1] See below for the reconciliation from Segment Adjusted EBITDA to net income.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Equity-Based Compensation Plan - Summary of Phantom Unit Award Activity (Details) - $ / shares		3 Months Ended
	Jul. 30, 2019	Mar. 31, 2020
Phantom Units
Number of Units
Outstanding at December 31, 2019		1,109,568
Granted		168,212
Settled		174,888
Forfeited		335
Outstanding at March 31, 2020		1,102,557
Weighted Average Fair Value
Outstanding at December 31, 2019		$ 35.97
Granted		20.49
Settled		36.29
Forfeited		33.55
Outstanding at March 31, 2020		$ 33.56
ANDX LP [Member] | Public
Equity Transactions And Share Based Compensation [Line Items]
Common Units Conversion Ratio - ANDX to MPLX	1.135

XML

Goodwill and Intangibles Goodwill (Details)		3 Months Ended	12 Months Ended
	Nov. 30, 2019	Mar. 31, 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		7,722,000,000	$ 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)	(1,197,000,000)
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

Debt Debt - Summary of Outstanding Borrowings - Interest Rates and Table Due Dates (Details)	3 Months Ended
	Mar. 31, 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

Revenue Remaining Performance Obligations (Details) $ in Millions	Mar. 31, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Contract with customer, liability	$ 224
Revenue, Remaining Performance Obligation, Amount	12,108	[1],[2],[3]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-04-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,344
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	9 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	$ 1,747
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	$ 1,717
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	$ 1,638
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	$ 5,662
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.

XML

Fair Value Measurements - Recurring - Changes in Level 3 Measurements (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 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
Total gains (losses) (realized and unrealized) included in earnings	[1]	0	0
Settlements		0	0
Fair value at end of period		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
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		(60)	(61)
Total gains (losses) (realized and unrealized) included in earnings	[1]	14	(6)
Settlements		1	2
Fair value at end of period		(45)	(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		$ 13	$ (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

Other Assets and Liabilities from Related Parties (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Other current assets	$ 45	$ 110
Current Assets, Related Parties	600	656
Operating Lease, Right-of-Use Asset	352	365
Other Assets, Related Parties, Noncurrent	677	303
Operating Lease, Liability, Current	67	66
Current Liabilities, Related Parties	297	1,008
Operating Lease, Liability, Noncurrent	284	302
Liabilities, Related Parties, Noncurrent	290	290
MPC
Related Party Transaction [Line Items]
Receivables - related parties	538	621
Prepaid Insurance	15	9
Sales-type Lease, Interest Income	26	4
Sales-type Lease, Unguaranteed Residual Asset	19	7
Due from Related Parties, Noncurrent	28	21
Operating Lease, Right-of-Use Asset	231	232
Net Investment in Lease, Noncurrent	399	43
Due to Related Parties, Current	227	911
Operating Lease, Liability, Current	1	1
Operating Lease, Liability, Noncurrent	230	230
Other Affiliates [Member]
Related Party Transaction [Line Items]
Receivables - related parties	21	22
Due to Related Parties, Current	16	37
Minimum Committed Volume Contracts [Member] | MPC
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	38	42
Reimbursable Projects [Member] | MPC
Related Party Transaction [Line Items]
Deferred Revenue Related Parties	14	16
Deferred Revenue, Noncurrent, Related Parties	54	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

Equity Method Investments - Summary of Equity Method Investment Financial Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019		Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 3,992				$ 5,275
Revenues and other income		120		$ 546	[1]
Costs and expenses		236		275	[1]
Income (loss) from operations		(116)		271	[1]
Net income (loss)		(151)		252	[1]
Income/(loss) from equity method investments(2)		(1,184)	[2],[3],[4]	77	[1],[5],[6],[7]
Current assets		645				864
Noncurrent assets		10,499				10,996
Current liabilities		348				437
Noncurrent liabilities		1,403				1,127
Equity Method Investment, Other than Temporary Impairment		$ 1,264
MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%
Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35.00%
LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41.00%
Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38.00%
W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%
Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		15.00%
Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		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%
Jefferson Dry Gas
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%
Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40.00%
Other VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues and other income		$ (217)		155	[1]
Costs and expenses		104		77	[1]
Income (loss) from operations		(321)		78	[1]
Net income (loss)		(337)		71	[1]
Income/(loss) from equity method investments(2)		(1,222)	[4]	27	[1]
Current assets		320				534
Noncurrent assets		5,384				5,862
Current liabilities		153				192
Noncurrent liabilities		544				305
Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues and other income		337		391	[1]
Costs and expenses		132		198	[1]
Income (loss) from operations		205		193	[1]
Net income (loss)		186		181	[1]
Income/(loss) from equity method investments(2)		38		50	[1]
Current assets		325				330
Noncurrent assets		5,115				5,134
Current liabilities		195				245
Noncurrent liabilities		$ 859				822
Indirect Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.10%
Direct Ownership Interest [Member] | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		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%
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%
Direct Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		52.00%
G&P
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		$ (60)				1,000
Difference between carrying amount and underlying equity portion related to goodwill		31				498
G&P | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	712				1,984
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	546				537
G&P | Jefferson Dry Gas
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	302				302
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	167				170
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	155				157
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		150				153
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	206				198
L&S
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		330				329
Difference between carrying amount and underlying equity portion related to goodwill		167				167
L&S | MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		479				481
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		271				265
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		239				238
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	200				202
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		190				190
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	163				134
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8],[9]	76				0
L&S | Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8],[9]	0				126
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		81				83
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	55				55
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Equity method investments		2,238				3,501
Income/(loss) from equity method investments(2)		(1,234)		32	[7]
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Equity method investments		1,754				$ 1,774
Income/(loss) from equity method investments(2)		$ 50		$ 45	[7]

[1] Financial information for the first quarter of 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.

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

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

[5] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[6] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[7] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[8] Investments deemed to be VIE’s. Some investments included within “Other” have also been deemed to be VIE’s.

[9] During the three months ended March 31, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

XML

Segment Information - Segment Adjusted EBITDA (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Segment Reporting Information [Line Items]
Depreciation and amortization	[1]	$ 325		$ 301	[2],[3],[4]
Total revenues from contracts with customers		1,781		1,708	[5]
Rental income		96		99	[3]
Income/(loss) from equity method investments(2)		(1,184)	[6],[7],[8]	77	[2],[3],[4],[9]
Other income		1		0	[3]
Total segment revenues and other income		(992)		(2,235)	[3],[5]
Investments in unconsolidated affiliates		(91)		(135)	[2]
L&S
Segment Reporting Information [Line Items]
Depreciation and amortization		(138)		(126)
Total revenues from contracts with customers		1,023		904	[5]
Investments in unconsolidated affiliates		54		7	[4]
G&P
Segment Reporting Information [Line Items]
Depreciation and amortization		(187)		(175)
Total revenues from contracts with customers		758		804	[5]
Investments in unconsolidated affiliates		37		128	[4]
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA		1,294		930	[4]
Operating Segments | L&S
Segment Reporting Information [Line Items]
Rental income		242		335	[4]
Income/(loss) from equity method investments(2)		50		45	[4]
Other income		51		12	[4]
Total segment revenues and other income	[1]	(1,366)		(1,296)	[4]
Adjusted EBITDA	[10]	872		559	[4]
Capital Expenditure		184		198	[4]
Operating Segments | G&P
Segment Reporting Information [Line Items]
Rental income		88		89	[4]
Income/(loss) from equity method investments(2)		(1,234)		32	[4]
Other income		14		14	[4]
Total segment revenues and other income	[1]	374		(939)	[4]
Adjusted EBITDA	[10]	422		371	[4]
Capital Expenditure		134		306	[4]
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA attributable to Predecessor	[11]	0		333	[4]
Service [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		612		614	[3],[5]
Service [Member] | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		84		86	[5]
Service [Member] | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		528		528	[5]
Service [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,004		889	[4]
Service [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		536		528	[4]
Product [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		169		216	[3]
Product [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		19		15	[4]
Product [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		222		276	[4]
Third Party [Member] | L&S
Segment Reporting Information [Line Items]
Total segment revenues and other income		(158)		(153)
Third Party [Member] | G&P
Segment Reporting Information [Line Items]
Total segment revenues and other income		$ (425)		$ (887)

[1] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] Financial information for the first quarter of 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 2020 period includes $1,264 million of impairment expense. See Note 4.

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

[9] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[10] See below for the reconciliation from Segment Adjusted EBITDA to net income.

[11] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Leases Leases Narrative (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	[2]	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	[1]	186	$ 279
Sales-type Lease, Lease Receivable		425
Sales-type Lease, Unguaranteed Residual Asset		19			$ 7
Refining Logistics [Member] | MPC
Sales-type Lease, Unguaranteed Residual Asset		$ 10

[1] These amounts are presented net of executory costs.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Equity - Cash Distributions (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended
		Apr. 28, 2020	Mar. 31, 2020	Mar. 31, 2019
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Contributions from:			$ 225	$ 15	[1]
Distribution Made to Limited Partner, Cash Distributions Declared			759	543
Partners, Total Subsequent Distribution Amount			759	543
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders			9	6	[1]
Partners' Capital Account, Distributions			738	776	[1]
Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Partners, Total Subsequent Distribution Amount			728	523	[2]
Preferred Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Partners, Total Subsequent Distribution Amount			20	20
Preferred Class B [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Partners, Total Subsequent Distribution Amount			11	0
Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Declaration Date		Apr. 28, 2020
Cash distributions declared per limited partner common unit		$ 0.6875
Distribution date		May 15, 2020
Date of record		May 08, 2020
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	[3]		$ 11	0
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
Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[3]		$ 728	$ 523
Cash distributions declared per limited partner common unit			$ 0.6875	$ 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		$ 728
Preferred Class B [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Contributions from:			$ 0	$ 0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders			0	0	[1]
Partners' Capital Account, Distributions			21	0	[1]
MPC | Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Contributions from:			225	0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders			0	0	[1]
Partners' Capital Account, Distributions			$ 446	$ 327	[1]
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%

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] The distribution on common units for the three months ended March 31, 2019 does not include the impact of the issuance of units in connection with the merger.

[3] See Note 7 for distribution information.

XML

Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020		Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 174
Property, plant and equipment, gross	26,587		$ 26,867
Less accumulated depreciation(1)	4,758	[1]	4,722
Property, plant and equipment, net	21,829		22,145
L&S
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,526		12,934
L&S | Terminals
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,637		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	1,176		1,109
L&S | Refineries and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,308		2,870
L&S | Land, building and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,827		1,817
L&S | Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	618		660
G&P
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14,061		13,933
G&P | Pipelines
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,349		7,159
G&P | Processing, fractionation and storage facilities
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,605		5,545
G&P | Land, building and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	491		484
G&P | Construction-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 616		$ 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	2 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 March 31, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020 as discussed below.

XML

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 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 March 31, 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.

	March 31, 2020					December 31, 2019
(In millions)	Assets		Liabilities			Assets		Liabilities
Significant unobservable inputs (Level 3)
Embedded derivatives in commodity contracts	$	—	$	(45	)	$	—	$	(60	)
Total carrying value on Consolidated Balance Sheets	$	—	$	(45	)	$	—	$	(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 $0.26 to $0.68 per gallon with a weighted average of $0.39 per gallon per the

current term of the embedded derivative and (2) the probability of renewal of 95 percent for the first five-year term and 83.5 percent for the second five-year term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. An increase in the probability of renewal would result in an increase in the fair value of the related embedded derivative liability. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of March 31, 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 March 31, 2020					Three Months Ended March 31, 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)	—		14			—		(6		)
Settlements	—		1			—		2
Fair value at end of period	—		(45		)	—		(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	$	—	$	13		$	—	$	(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:

	March 31, 2020				December 31, 2019
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-term debt	$	18,352	$	20,560	$	21,054	$	19,800
SMR liability	$	77	$	79	$	90	$	80

XML

Supplemental Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2020

Supplemental Cash Flow Elements [Abstract]

Summary of Supplemental Cash Flow Information [Table Text Block]

	Three Months Ended March 31,
(In millions)	2020			2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	210		$	173
Non-cash investing and financing activities:
Net transfers of property, plant and equipment from (to) 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:

	Three Months Ended March 31,
(In millions)	2020			2019
(Decrease)/increase in capital accruals	$	(61	)	$	(71	)

XML

Equity-Based Compensation Plan

3 Months Ended

Mar. 31, 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 three months ended March 31, 2020:

	Number of Units		Weighted Average Fair Value
Outstanding at December 31, 2019	1,109,568		$	35.97
Granted	168,212		20.49
Settled	(174,888	)	36.29
Forfeited	(335	)	33.55
Outstanding at March 31, 2020	1,102,557		$	33.56

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 three months ended March 31, 2020:

	Number of Units
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	(1,169,354	)
Forfeited	(18,750	)
Outstanding at March 31, 2020	3,116,454

XML

Debt

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Debt

Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	March 31, 2020			December 31, 2019
MPLX LP:
Bank revolving credit facility	$	750		$	—
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)	14			19
Total	20,864			20,119
Unamortized debt issuance costs	(103		)	(106		)
Unamortized discount/premium	(290		)	(300		)
Amounts due within one year	(4		)	(9		)
Total long-term debt due after one year	$	20,467		$	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 three months ended March 31, 2020, MPLX borrowed $1,325 million under the MPLX Credit Agreement, at an average interest rate of 2.139 percent, and repaid $575 million. At March 31, 2020, MPLX had $750 million in outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of $2.75 billion, or 78.6 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 March 31, 2020, MPLX had drawn $1.0 billion on the term loan at an average interest rate of 2.273 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.

XML

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)	[2]	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, 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
Contributions from noncontrolling interests		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

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	[1]
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ (2,716)	$ 689	[2],[3],[4]
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)	(2,717)	690
Less comprehensive income attributable to:
Noncontrolling interests	8	6
Comprehensive Income (loss), Net of Tax, Attributable to Predecessor	0	180
Comprehensive income/(loss) attributable to MPLX LP	$ (2,725)	$ 504

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Inventories (Summary of Inventories) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
NGLs	$ 1	$ 5
Line fill	6	10
Spare parts, materials and supplies	98	95
Total inventories	$ 105	$ 110

XML

Segment Information (Details)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Number of reportable segments	2

XML

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Accrued liabilities for environmental remediation	$ 17	$ 19
Contractual commitments to acquire property, plant and equipment	318
MPC
Commitments And Contingencies [Line Items]
Due to Related Parties, Current	227	911
Environmental Loss Contingency [Member] | MPC
Commitments And Contingencies [Line Items]
Due to Related Parties, Current	$ 0	$ 0
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

XML

Equity-Based Compensation Plan - Summary of Performance Unit Award Activity (Detail) - Performance Shares [Member]	3 Months Ended
	Mar. 31, 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	(18,750)
Outstanding at March 31, 2020	3,116,454

XML

Equity - Changes in Partners Capital, Unit Rollforward (Details) - USD ($) $ / shares in Units, $ in Millions					3 Months Ended			12 Months Ended
		Apr. 28, 2020	Jul. 30, 2019	Jul. 29, 2019	Mar. 31, 2020	Mar. 31, 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					$ 2,736	$ (669)	[1]
Partners, Total Subsequent Distribution Amount					759	543
Contributions from:					225	15	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(738)	(776)	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest					13,356	17,730	[1]	$ 16,613	$ 17,731
Distribution Made to Limited Partner, Cash Distributions Declared					759	543
Preferred Class B [Member]
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity					(11)	0	[1]
Contributions from:					0	0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(21)	0	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest					$ 601	0	[1]	$ 611	0
Limited Partners Common Units
Stockholders Equity [Line Items]
Balance at December 31, 2019					1,058,355,471
Unit-based compensation awards					151,878
Balance at March 31, 2020					1,058,507,349			1,058,355,471
Distribution Made to Limited Partner, Cash Distributions Declared	[2]				$ 728	523
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		$ 728
Series B Preferred Stock [Member] | Preferred Partner [Member]
Stockholders Equity [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared	[2]				$ 11	0
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]
Partners, Total Subsequent Distribution Amount					$ 11	0
Preferred Class B [Member] | Preferred Partner [Member]
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity					(11)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest					601			$ 611
MPC | Limited Partners Common Units
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity					$ (1,733)	307	[1]
Units issued			161,000,000		666,000,000			666,000,000
Contributions from:					$ 225	0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(446)	(327)	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest					$ 3,014	(1,632)	[1]	$ 4,968	(1,612)
Units Outstanding					666,000,000			666,000,000
Public | Limited Partners Common Units
Stockholders Equity [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity					$ (1,022)	176	[1]
Units issued			102,000,000		393,000,000			392,000,000
Contributions from:					$ 0	0	[1]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(271)	(188)	[1]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest					$ 9,509	$ 8,326	[1]	$ 10,800	$ 8,336
Units Outstanding					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					$ 0			$ 1

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] See Note 7 for distribution information.

XML

Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]

As of March 31, 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)	March 31, 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	$	—	$	(2	)	$	—	$	(5	)
Other noncurrent assets / Deferred credits and other liabilities	—		(43		)	—		(55		)
Total	$	—	$	(45	)	$	—	$	(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 March 31,
(In millions)	2020			2019
Product sales
Realized (loss)/gain	$	—		$	—
Unrealized (loss)/gain	—			—
Product sales derivative (loss)/gain	—			—
Purchased product costs
Realized (loss)/gain	(1		)	(2		)
Unrealized gain/(loss)	15			(4		)
Purchased product costs derivative gain/(loss)	14			(6		)
Cost of revenues
Realized (loss)/gain	—			—
Unrealized (loss)/gain	—			—
Cost of revenues derivative (loss)/gain	—			—
Total derivative gain/(loss)	$	14		$	(6	)

XML

Accumulated Other Comprehensive Income (Tables)

3 Months Ended

Mar. 31, 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 March 31, 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 March 31, 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 March 31, 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 March 31, 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.

XML

Accumulated Other Comprehensive Income

3 Months Ended

Mar. 31, 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 March 31, 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 March 31, 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 March 31, 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 March 31, 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.

XML

Derivative Financial Instruments

3 Months Ended

Mar. 31, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities Disclosure [Text Block]

Derivative Financial Instruments

As of March 31, 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, the probability of the producer customer exercising its option to extend and the estimated favorability of these contracts compared to current market conditions. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. As of March 31, 2020 and December 31, 2019, the estimated fair value of this contract was a liability of $45 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 March 31, 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)	March 31, 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	$	—	$	(2	)	$	—	$	(5	)
Other noncurrent assets / Deferred credits and other liabilities	—		(43		)	—		(55		)
Total	$	—	$	(45	)	$	—	$	(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 March 31,
(In millions)	2020			2019
Product sales
Realized (loss)/gain	$	—		$	—
Unrealized (loss)/gain	—			—
Product sales derivative (loss)/gain	—			—
Purchased product costs
Realized (loss)/gain	(1		)	(2		)
Unrealized gain/(loss)	15			(4		)
Purchased product costs derivative gain/(loss)	14			(6		)
Cost of revenues
Realized (loss)/gain	—			—
Unrealized (loss)/gain	—			—
Cost of revenues derivative (loss)/gain	—			—
Total derivative gain/(loss)	$	14		$	(6	)

XML

Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents		$ 57	$ 15
Receivables, net		522	593
Current Assets, Related Parties		600	656
Inventories		105	110
Other current assets		45	110
Total current assets		1,329	1,484
Equity method investments		3,992	5,275
Property, plant and equipment, net		21,829	22,145
Intangibles, net		1,055	1,270
Goodwill		7,722	9,536
Operating Lease, Right-of-Use Asset		352	365
Other Assets, Related Parties, Noncurrent		677	303
Other noncurrent assets		50	52
Total assets		37,006	40,430
Current liabilities:
Accounts payable		138	242
Accrued Liabilities, Current		135	187
Current Liabilities, Related Parties		297	1,008
Accrued Property Plant and Equipment Current		234	283
Accrued interest payable		214	210
Operating Lease, Liability, Current		67	66
Other current liabilities		129	136
Total current liabilities		1,214	2,132
Long-term deferred revenue		241	217
Liabilities, Related Parties, Noncurrent		290	290
Long-term debt		20,467	19,704
Deferred income taxes		11	12
Operating Lease, Liability, Noncurrent		284	302
Deferred credits and other liabilities		175	192
Total liabilities		22,682	22,849
Commitments and contingencies (see Note 21)
Series A preferred units		968	968
Equity
Total MPLX LP partners’ capital		13,108	16,364
Accumulated other comprehensive loss	[1]	(16)	(15)
Noncontrolling interests		248	249
Total equity		13,356	16,613
Total liabilities, preferred units and equity		37,006	40,430
MPC
Current assets:
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		601	611
Limited Partners Common Units | Public
Equity
Total MPLX LP partners’ capital		9,509	10,800
Total equity		9,509	10,800
Limited Partners Common Units | MPC
Equity
Total MPLX LP partners’ capital		3,014	4,968
Total equity		3,014	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.”

XML

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 01, 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	Mar. 31, 2020
Amendment Flag	false
Entity File Number	001-35714
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
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		1,058,603,592
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

Description of the Business and Basis of Presentation

3 Months Ended

Mar. 31, 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 recent 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 the midstream services we provide. 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 our 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 have continued to refine and update production forecasts in response to the current environment, which has 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.

(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 months ended March 31, 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.

XML

Related Party Agreements and Transactions (Tables)

3 Months Ended

Mar. 31, 2020

Related Party Transactions [Abstract]

Other Long-term Debt, Noncurrent

Activity on the MPC Loan Agreement was as follows:

(In millions)	Three Months Ended March 31, 2020			Year Ended December 31, 2019
Borrowings	$	1,667		$	8,540
Average interest rate of borrowings	2.833		%	3.441		%
Repayments	$	2,261		$	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 March 31,
(In millions)	2020		2019
Service revenues - related parties
MPC	$	927	$	803
Other	1		—
Total Service revenue - related parties	928		803
Rental income - related parties
MPC	234		325
Product sales - related parties(1)
MPC	33		41
Other income - related parties
MPC	48		10
Other	16		16
Total Other income - related parties	$	64	$	26

(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 months ended March 31, 2020, these sales totaled $173 million. For the three months ended March 31, 2019, these sales totaled $223 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 March 31,
(In millions)	2020		2019
Rental cost of sales - related parties
MPC	$	46	$	43
Purchases - related parties
MPC	271		273
Other	5		5
Total Purchase - related parties	276		278
General and administrative expenses
MPC	$	64	$	62

Schedule of Related Party Transactions [Table Text Block]

(In millions)	March 31, 2020		December 31, 2019
Current assets - related parties
Receivables - MPC	$	538	$	621
Receivables - Other	21		22
Prepaid - MPC	15		9
Lease Receivables - MPC	26		4
Total	600		656
Noncurrent assets - related parties
Long-term receivables - MPC	28		21
Right of use assets - MPC	231		232
Long-term lease receivables - MPC	399		43
Unguaranteed residual asset - MPC	19		7
Total	677		303
Current liabilities - related parties
Payables - MPC	227		911
Payables - Other	16		37
Operating lease liabilities - MPC	1		1
Deferred revenue - Minimum volume deficiencies - MPC	38		42
Deferred revenue - Project reimbursements - MPC	14		16
Deferred revenue - Project reimbursements - Other	1		1
Total	297		1,008
Long-term liabilities - related parties
Long-term operating lease liabilities - MPC	230		230
Long-term deferred revenue - Project reimbursements - MPC	54		53
Long-term deferred revenue - Project reimbursements - Other	6		7
Total	$	290	$	290

XML

Segment Information (Tables)

3 Months Ended

Mar. 31, 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 March 31,
(In millions)	2020			2019(1)
L&S
Service revenue	$	1,004		$	889
Rental income	242			335
Product related revenue	19			15
Income from equity method investments	50			45
Other income	51			12
Total segment revenues and other income(2)	1,366			1,296
Segment Adjusted EBITDA(3)	872			559
Capital expenditures	184			198
Investments in unconsolidated affiliates	54			7
G&P
Service revenue	536			528
Rental income	88			89
Product related revenue	222			276
(Loss)/income from equity method investments	(1,234		)	32
Other income	14			14
Total segment revenues and other (loss)/income(2)	(374		)	939
Segment Adjusted EBITDA(3)	422			371
Capital expenditures	134			306
Investments in unconsolidated affiliates	$	37		$	128

(1) Financial information for the first quarter of 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 $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

(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)	March 31, 2020		December 31, 2019
Segment assets
Cash and cash equivalents	$	57	$	15
L&S	20,891		20,810
G&P	16,058		19,605
Total assets	$	37,006	$	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 March 31,
(In millions)	2020			2019(1)
Reconciliation to Net (loss)/income:
L&S Segment Adjusted EBITDA	$	872		$	559
G&P Segment Adjusted EBITDA	422			371
Total reportable segments	1,294			930
Depreciation and amortization(2)	(325		)	(301		)
Benefit for income taxes	—			1
Amortization of deferred financing costs	(14		)	(7		)
Non-cash equity-based compensation	(5		)	(7		)
Impairment expense	(2,165		)	—
Net interest and other financial costs	(216		)	(217		)
(Loss)/income from equity method investments	(1,184		)	77
Distributions/adjustments related to equity method investments	(124		)	(122		)
Unrealized derivative gains/(losses)(3)	15			(4		)
Acquisition costs	—			(1		)
Other	(1		)	—
Adjusted EBITDA attributable to noncontrolling interests	9			7
Adjusted EBITDA attributable to Predecessor(4)	—			333
Net (loss)/income	$	(2,716	)	$	689

(1) Financial information for the first quarter of 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 $126 million for the three months ended March 31, 2020 and 2019, respectively. Depreciation and amortization attributable to G&P was $187 million and $175 million for the three months ended March 31, 2020 and 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.

XML

Inventories

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

Inventories

Inventories

Inventories consist of the following:

(In millions)	March 31, 2020		December 31, 2019
NGLs	$	1	$	5
Line fill	6		10
Spare parts, materials and supplies	98		95
Total inventories	$	105	$	110

XML

Net Income Per Limited Partner Unit

3 Months Ended

Mar. 31, 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 months ended March 31, 2020 and 2019 include:

	Three Months Ended March 31,
	2020	2019
Common Units	ü	ü
Equity-based compensation awards	ü	ü
Series A preferred units	ü	ü
Series B preferred units	ü
TexNew Mex units	ü

For the three months ended March 31, 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 months ended March 31, 2020 and 2019 were 1 million and less than 1 million, respectively.

	Three Months Ended March 31,
(In millions)	2020			2019
Net income attributable to MPLX LP	$	(2,724	)	$	503
Less: Distributions declared on Series A preferred units(1)	20			20
Distributions declared on Series B preferred units(1)	11			—
Limited partners’ distributions declared on MPLX common units (including common units of general partner)(1)	728			523
Undistributed net loss attributable to MPLX LP	$	(3,483	)	$	(40	)

(1) See Note 7 for distribution information.

	Three Months Ended March 31, 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	$	728		$	20	$	11	$	759
Undistributed net loss attributable to MPLX LP	(3,483		)	—		—		(3,483		)
Net income attributable to MPLX LP(1)	$	(2,755	)	$	20	$	11	$	(2,724	)
Weighted average units outstanding:
Basic	1,058
Diluted	1,058
Net income attributable to MPLX LP per limited partner unit:
Basic	$	(2.60	)
Diluted	$	(2.60	)

(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 March 31, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	523		$	20	$	543
Undistributed net loss attributable to MPLX LP	(40		)	—		(40		)
Net income attributable to MPLX LP(1)	$	483		$	20	$	503
Weighted average units outstanding:
Basic	794
Diluted	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.61
Diluted	$	0.61

(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.

XML

Accounting Standards Accounting Standards

3 Months Ended

Mar. 31, 2020

Accounting Changes and Error Corrections [Abstract]

New Accounting Pronouncements and Changes in Accounting Principles [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 March 31, 2020, we reported $522 million of accounts receivable, net of allowances of $1 million.

We are also exposed to credit losses from off-balance sheet exposures, such as guarantees of joint venture debt. See Note 21 for more information on these off-balance sheet exposures.

We also adopted the following ASU during the first three 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

XML

Goodwill and Intangibles Intangibles (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 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		96
Finite-Lived Intangible Assets, Amortization Expense, Year Two		128
Finite-Lived Intangible Assets, Amortization Expense, Year Three		128
Finite-Lived Intangible Assets, Amortization Expense, Year Four		128
Finite-Lived Intangible Assets, Amortization Expense, Year Five		124
Finite-Lived Intangible Assets, Amortization Expense, after Year Five		451
Finite-Lived Intangible Assets, Net		1,055
Finite-Lived Intangible Assets, Accumulated Amortization	[1]	(516)		(301)
Intangibles, net		1,055		1,270
L&S
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets		9
Finite-Lived Intangible Assets, Gross		283		283
Finite-Lived Intangible Assets, Accumulated Amortization	[1]	(54)		(45)
Intangibles, net		$ 229		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		$ 29
Finite-Lived Intangible Assets, Gross		1,288		1,288
Finite-Lived Intangible Assets, Accumulated Amortization	[1]	(462)	[2]	(256)
Intangibles, net		$ 826		$ 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 three months ended March 31, 2020 was $29 million and $9 million, respectively.

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

XML

Debt - Additional Information (Detail) - USD ($) $ in Millions				3 Months Ended
	Sep. 26, 2019	Sep. 09, 2019	Jul. 21, 2017	Mar. 31, 2020	Mar. 31, 2019	[1]	Dec. 31, 2019	Jul. 30, 2019
Debt Instrument [Line Items]
Repayments of Long-term Debt				$ 581	$ 821
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				750			$ 0
MPLX Revolving Credit Facility due July 2024 [Member] | MPLX LP
Debt Instrument [Line Items]
Proceeds from Lines of Credit				$ 1,325
Debt Instrument, Interest Rate, Effective Percentage				2.139%
Repayments of Long-term Lines of Credit				$ 575
Letters of Credit Outstanding				1
Line of Credit Facility, Remaining Borrowing Capacity				$ 2,750
Line of Credit Facility, Remaining Borrowing Capacity, Percentage				78.60%
Bank revolving credit facility due 2022 | MPLX LP
Debt Instrument [Line Items]
Debt Instrument, Term			5 years
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				2.273%
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 first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 210	$ 173
Non-cash investing and financing activities:
Net transfers of property, plant and equipment from (to) materials and supplies inventories	$ (1)	$ 1

XML

Fair Value Measurements - Reported (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 20,560	$ 19,800
SMR liability	79	80
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	18,352	21,054
SMR liability	$ 77	$ 90

XML

Debt - Summary of Outstanding Borrowings (Detail) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019	Sep. 09, 2019
Debt Instrument [Line Items]
Total		$ 20,864	$ 20,119
Unamortized debt issuance costs		(103)	(106)
Unamortized discount/premium		(290)	(300)
Amounts due within one year		(4)	(9)
Total long-term debt due after one year		20,467	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]	14	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		$ 750	$ 0
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

Equity-Based Compensation Plan - Additional Information (Detail)	3 Months Ended
	Mar. 31, 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

XML

Summary of Charges for Employee Services and Omnibus Agreements (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Purchases - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	$ 276	$ 278
MPC | Rental cost of sales - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	46	43
MPC | Purchases - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	271	273
MPC | General and administrative expenses
Related Party Transaction [Line Items]
Labor and Related Expense	64	62
Other Affiliates [Member] | Purchases - related parties
Related Party Transaction [Line Items]
Labor and Related Expense	5	5
Construction-in-progress | MPC
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 36	$ 41

XML

Acquisitions Andeavor Logistics (Details) - USD ($) $ in Millions			3 Months Ended
		Jul. 30, 2019	Mar. 31, 2020		Mar. 31, 2019		Dec. 31, 2019	Sep. 09, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Cash and cash equivalents			$ 57				$ 15
Receivables, net			522				593
Inventories			105				110
Other current assets			45				110
Assets, Current			1,329				1,484
Equity method investments			3,992				5,275
Property, plant and equipment, net			21,829				22,145
Intangibles, net			1,055				1,270
Other noncurrent assets			50				52
Assets			37,006				40,430
Accounts payable			138				242
Accrued Liabilities, Current			135				187
Accrued interest payable			214				210
Other current liabilities			129				136
Liabilities, Current			1,214				2,132
Long-term deferred revenue			241				217
Liabilities, Related Parties, Noncurrent			290				290
Long-term debt			20,467				19,704
Deferred credits and other liabilities			175				192
Liabilities			22,682				22,849
Series A preferred units			968				968
Total MPLX LP partners’ capital			13,108				16,364
Accumulated other comprehensive loss	[1]		(16)		$ (15)		(15)		$ (16)
Revenues			992		2,235	[2],[3]
Goodwill			7,722				9,536		10,016
Net Income (Loss) Attributable to Parent			(2,724)	[4]	503	[2],[5]
Acquisition Costs, Period Cost			0		1	[6]
Noncontrolling interests			248				249
Partners' Capital, Including Portion Attributable to Noncontrolling Interest			13,356		17,730	[7]	16,613		17,731
Liabilities and Equity			37,006				40,430
Net income/(loss)			(2,716)		689	[2],[6],[8],[9]
Andeavor Logistics [Member]
Business Acquisition [Line Items]
Revenues					589
Acquisition Costs, Period Cost					1
Net income/(loss)					$ 180
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			229				238
Goodwill			$ 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			$ 826				1,032
Goodwill			$ 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 first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the first quarter of 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] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[7] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[8] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[9] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Leases Lessor Disclosure (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2020				Three Months Ended March 31, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	186	$	63	$	279	$	65
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		N/A		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		N/A		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	N/A		N/A		N/A

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

(2)

Financial information for the first quarter of 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 March 31, 2020				Three Months Ended March 31, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	186	$	63	$	279	$	65
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		N/A		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		N/A		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	N/A		N/A		N/A

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

(2)

Financial information for the first quarter of 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 with MPC as of March 31, 2020:

(In millions)	Related Party
2020	$	129
2021	157
2022	157
2023	158
2024	158
2025 and thereafter	461
Total minimum future rentals	1,220
Less: present value discount	795
Lease receivable	$	425

XML

Goodwill and Intangibles Goodwill and Intangibles (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2020	7,722		—			7,722
Gross goodwill as of March 31, 2020	7,722		3,141			10,863
Accumulated impairment losses	—		(3,141		)	(3,141		)
Balance as of March 31, 2020	$	7,722	$	—		$	7,722

XML

Revenue (Tables)

3 Months Ended

Mar. 31, 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 months ended March 31, 2020 and 2019:

	Three Months Ended March 31, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	84	$	528	$	612
Service revenue - related parties	920		8		928
Service revenue - product related	—		39		39
Product sales	15		154		169
Product sales - related parties	4		29		33
Total revenues from contracts with customers	$	1,023	$	758	1,781
Non-ASC 606 (loss)/revenue(1)					(789		)
Total revenues and other income					$	992

	Three Months Ended March 31, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	86	$	528	$	614
Service revenue - related parties	803		—		803
Service revenue - product related	—		34		34
Product sales	11		205		216
Product sales - related parties	4		37		41
Total revenues from contracts with customers	$	904	$	804	1,708
Non-ASC 606 revenue(1)					527
Total revenues and other income					$	2,235

(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 first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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

The tables below reflect the changes in our contract balances for the three-month periods ended March 31, 2020 and 2019:

(In millions)	Balance at December 31, 2019(1)		Additions/ (Deletions)			Revenue Recognized(2)			Balance at March 31, 2020
Contract assets	$	39	$	(27	)	$	—		$	12
Deferred revenue	23		5			(3		)	25
Deferred revenue - related parties	53		12			(16		)	49
Long-term deferred revenue	90		6			—			96
Long-term deferred revenue - related parties	$	55	$	1		$	—		$	56

(In millions)	Balance at December 31, 2018(1)		Additions/ (Deletions)(3)			Revenue Recognized(2)(3)			Balance at March 31, 2019(3)
Contract assets	$	36	$	(17	)	$	—		$	19
Deferred revenue	13		1			(1		)	13
Deferred revenue - related parties	65		9			(16		)	58
Long-term deferred revenue	56		1			—			57
Long-term deferred revenue - related parties	$	52	$	—		$	—		$	52

(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 first quarter of 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 March 31, 2020, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $224 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	$	1,344
2021	1,747
2022	1,717
2023	1,638
2024 and thereafter	5,662
Total revenue on remaining performance obligations(1),(2),(3)	$	12,108

(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.

XML

Segment Information - Assets by Segment (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Segment Reporting, Other Significant Reconciling Item [Line Items]
Cash and cash equivalents	$ 57	$ 15
Assets	37,006	40,430
L&S | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Assets	20,891	20,810
G&P | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Assets	$ 16,058	$ 19,605

XML

Leases Lessor Maturity Table (Details) $ in Millions	Mar. 31, 2020 USD ($)
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	129
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Next Twelve Months	157
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	157
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	158
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years	158
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter	461
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	1,220
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount	795
Sales-type Lease, Lease Receivable	$ 425

XML

Series A Preferred Units (Narrative) (Details) - $ / shares shares in Millions	Apr. 28, 2020	May 13, 2016	Mar. 31, 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	Apr. 28, 2020
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.6875

XML

Consolidated Statements of Cash Flows - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019	[1]
Equity Method Investment, Other than Temporary Impairment		$ 1,264
Proceeds from Contributions from Parent		14		$ 12
Operating activities:
Net income/(loss)		(2,716)		689	[2],[3],[4]
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Amortization of deferred financing costs		14		7
Depreciation and amortization	[5]	325		301	[3],[4]
Goodwill and Intangible Asset Impairment		2,165		0	[3],[4]
Deferred income taxes		0		(2)
(Gain)/loss on disposal of assets		0		1
Loss/(income) from equity method investments(2)		1,184	[6],[7],[8]	(77)	[3],[4],[9]
Distributions from unconsolidated affiliates		119		115
Changes in:
Current receivables		71		6
Inventories		3		4
Fair value of derivatives		(15)		7
Current accounts payable and accrued liabilities		(142)		(69)
Current assets/current liabilities - related parties		(52)		(157)
Increase (Decrease) in Other Operating Assets and Liabilities, Net		(4)		0
Deferred revenue		27		13
All other, net		30		15
Net cash provided by operating activities		1,009		853
Investing activities:
Additions to property, plant and equipment		(379)		(575)
Proceeds from Contributions from Affiliates		0		1
Disposal of assets		39		7
Investments in unconsolidated affiliates		(91)		(135)
Distributions from unconsolidated affiliates - return of capital		69		2
Net cash used in investing activities		(362)		(700)
Financing activities:
Long-term debt - borrowings		1,325		1,404
Long-term debt - repayments		(581)		(821)
Related party debt - borrowings		1,667		1,405
Related party debt - repayments		(2,261)		(1,405)
Distributions to noncontrolling interests		(9)		(6)
Distributions to unitholders and general partner		(717)		(515)
Contributions from noncontrolling interests		0		94	[10]
All other, net		(2)		(5)
Net cash used in financing activities		(605)		(116)
Net (decrease)/increase in cash, cash equivalents and restricted cash		42		37
Cash, cash equivalents and restricted cash at beginning of period		15		85
Cash, cash equivalents and restricted cash at end of period		57		122
Series A Preferred Stock [Member] | Preferred Partner [Member]
Financing activities:
Distributions to preferred unitholders		(20)		(20)
Series B Preferred Stock [Member] | Preferred Partner [Member]
Payments of Distributions on Preferred Units from Predecessor		0		259
Financing activities:
Distributions to preferred unitholders		$ (21)		$ 0

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

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

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

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

[9] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[10] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Interest Costs Capitalized	$ 13	$ 11

XML

Revenue

3 Months Ended

Mar. 31, 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 months ended March 31, 2020 and 2019:

	Three Months Ended March 31, 2020
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	84	$	528	$	612
Service revenue - related parties	920		8		928
Service revenue - product related	—		39		39
Product sales	15		154		169
Product sales - related parties	4		29		33
Total revenues from contracts with customers	$	1,023	$	758	1,781
Non-ASC 606 (loss)/revenue(1)					(789		)
Total revenues and other income					$	992

	Three Months Ended March 31, 2019(2)
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	86	$	528	$	614
Service revenue - related parties	803		—		803
Service revenue - product related	—		34		34
Product sales	11		205		216
Product sales - related parties	4		37		41
Total revenues from contracts with customers	$	904	$	804	1,708
Non-ASC 606 revenue(1)					527
Total revenues and other income					$	2,235

(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 first quarter of 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 three-month periods ended March 31, 2020 and 2019:

(In millions)	Balance at December 31, 2019(1)		Additions/ (Deletions)			Revenue Recognized(2)			Balance at March 31, 2020
Contract assets	$	39	$	(27	)	$	—		$	12
Deferred revenue	23		5			(3		)	25
Deferred revenue - related parties	53		12			(16		)	49
Long-term deferred revenue	90		6			—			96
Long-term deferred revenue - related parties	$	55	$	1		$	—		$	56

(In millions)	Balance at December 31, 2018(1)		Additions/ (Deletions)(3)			Revenue Recognized(2)(3)			Balance at March 31, 2019(3)
Contract assets	$	36	$	(17	)	$	—		$	19
Deferred revenue	13		1			(1		)	13
Deferred revenue - related parties	65		9			(16		)	58
Long-term deferred revenue	56		1			—			57
Long-term deferred revenue - related parties	$	52	$	—		$	—		$	52

(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 first quarter of 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 March 31, 2020, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $224 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	$	1,344
2021	1,747
2022	1,717
2023	1,638
2024 and thereafter	5,662
Total revenue on remaining performance obligations(1),(2),(3)	$	12,108

(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.

XML

Goodwill and Intangibles (Notes)

3 Months Ended

Mar. 31, 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.

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 is 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 March 31, 2020	7,722		—			7,722
Gross goodwill as of March 31, 2020	7,722		3,141			10,863
Accumulated impairment losses	—		(3,141		)	(3,141		)
Balance as of March 31, 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 were 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 March 31, 2020 and December 31, 2019 is shown below:

		March 31, 2020							December 31, 2019
(In millions)	Useful Life	Gross		Accumulated Amortization(1)(2)			Net		Gross		Accumulated Amortization			Net
L&S	6 - 8 years	$	283	$	(54	)	$	229	$	283	$	(45	)	$	238
G&P	6 - 25 years	1,288		(462		)	826		1,288		(256		)	1,032
		$	1,571	$	(516	)	$	1,055	$	1,571	$	(301	)	$	1,270

(1) Amortization expense attributable to the G&P and L&S segments for the three months ended March 31, 2020 was $29 million and $9 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 March 31, 2020 is as follows:

(In millions)
2020	$	96
2021	128
2022	128
2023	128
2024	124
Thereafter	451
Total	$	1,055

XML

Leases Leases (Notes)

3 Months Ended

Mar. 31, 2020

Disclosure Text Block [Abstract]

Leases of Lessor Disclosure [Text Block]

Leases

For the three months ended March 31, 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 three months ended March 31, 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 March 31, 2020				Three Months Ended March 31, 2019
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Operating lease revenue(1)(2)	$	186	$	63	$	279	$	65
Sales-type leases:
Profit/(loss) recognized at the commencement date	—		N/A		N/A		N/A
Interest income (Sales-type lease revenue- fixed minimum)	38		N/A		N/A		N/A
Interest income (Revenue from variable lease payments)	$	—	N/A		N/A		N/A

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

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

The following is a schedule of future payments on the sales-type leases with MPC as of March 31, 2020:

(In millions)	Related Party
2020	$	129
2021	157
2022	157
2023	158
2024	158
2025 and thereafter	461
Total minimum future rentals	1,220
Less: present value discount	795
Lease receivable	$	425

XML

Series A Preferred Units

3 Months Ended

Mar. 31, 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 April 28, 2020, MPLX declared a quarterly cash distribution of $0.6875 per common unit for the first 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 March 31, 2020. The changes in the redeemable preferred balance from December 31, 2019 through March 31, 2020 are summarized below:

(In millions)	Redeemable Series A Preferred Units
Balance at December 31, 2019	$	968
Net income allocated	20
Distributions received by Series A preferred unitholders	(20		)
Balance at March 31, 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.

XML

Equity Method Investments

3 Months Ended

Mar. 31, 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
	March 31,	March 31,		December 31,
(In millions, except ownership percentages)	2020	2020		2019
L&S
MarEn Bakken Company LLC	25%	$	479	$	481
Illinois Extension Pipeline Company, L.L.C.	35%	271		265
LOOP LLC	41%	239		238
Andeavor Logistics Rio Pipeline LLC(1)	67%	200		202
Minnesota Pipe Line Company, LLC	17%	190		190
Whistler Pipeline LLC(1)	38%	163		134
W2W Holdings LLC(1)(2)	50%	76		—
Wink to Webster Pipeline LLC(1)(2)	15%	—		126
Explorer Pipeline Company	25%	81		83
Other(1)		55		55
Total L&S		1,754		1,774
G&P
MarkWest Utica EMG, L.L.C.(1)	57%	712		1,984
Sherwood Midstream LLC(1)	50%	546		537
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(1)	67%	302		302
Rendezvous Gas Services, L.L.C.(1)	78%	167		170
Sherwood Midstream Holdings LLC(1)	52%	155		157
Centrahoma Processing LLC	40%	150		153
Other(1)		206		198
Total G&P		2,238		3,501
Total		$	3,992	$	5,275

(1) Investments deemed to be VIE’s. Some investments included within “Other” have also been deemed to be VIE’s.

(2) During the three months ended March 31, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

For those entities that have been deemed to be VIE’s, 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, since 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, 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 March 31, 2020, MPLX has a 24.1 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 three months ended March 31, 2020.

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. During the first quarter of 2020, 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.

Summarized financial information for MPLX’s equity method investments for the three months ended March 31, 2020 and 2019 is as follows:

	Three Months Ended March 31, 2020
(In millions)	VIEs			Non-VIEs		Total
Revenues and other income	$	(217	)	$	337	$	120
Costs and expenses	104			132		236
Income from operations	(321		)	205		(116		)
Net income	(337		)	186		(151		)
(Loss)/income from equity method investments(1)	$	(1,222	)	$	38	$	(1,184	)

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

	Three Months Ended March 31, 2019(1)
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	155	$	391	$	546
Costs and expenses	77		198		275
Income from operations	78		193		271
Net income	71		181		252
Income from equity method investments	$	27	$	50	$	77

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

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

	March 31, 2020
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	320	$	325	$	645
Noncurrent assets	5,384		5,115		10,499
Current liabilities	153		195		348
Noncurrent liabilities	$	544	$	859	$	1,403

	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 March 31, 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 $60 million, after the impairment charges recognized during the quarter. 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 March 31, 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 March 31, 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 March 31, 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, respectively.

XML

Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 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	March 31, 2020		December 31, 2019
L&S
Pipelines	2-51 years	$	5,637	$	5,572
Refining Logistics	13-40 years	2,308		2,870
Terminals	2-40 years	1,176		1,109
Marine	15-20 years	960		906
Land, building and other	1-61 years	1,827		1,817
Construction-in progress		618		660
Total L&S property, plant and equipment		12,526		12,934
G&P
Gathering and transportation	5-40 years	7,349		7,159
Processing and fractionation	15-40 years	5,605		5,545
Land, building and other	3-40 years	491		484
Construction-in-progress		616		745
Total G&P property, plant and equipment		14,061		13,933
Total property, plant and equipment		26,587		26,867
Less accumulated depreciation(1)		4,758		4,722
Property, plant and equipment, net		$	21,829	$	22,145

(1) The March 31, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020 as discussed below.

XML

Net Income Per Limited Partner Unit Accounting Policy (Policies)

3 Months Ended

Mar. 31, 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.

XML

Equity (Tables)

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Schedule of Stockholders Equity [Table Text Block]

The changes in the number of common units outstanding during the three months ended March 31, 2020 are summarized below:

(In units)	Common
Balance at December 31, 2019	1,058,355,471
Unit-based compensation awards	151,878
Balance at March 31, 2020	1,058,507,349

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 March 31, 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	11
Distributions received by Series B preferred unitholders	(21		)
Balance at March 31, 2020	$	601

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 months ended March 31, 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 March 31,
(In millions)	2020		2019(1)
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	728	$	523
Series A preferred unit distributions	20		20
Series B preferred unit distributions	11		—
Total cash distributions declared	$	759	$	543

(1)

The distribution on common units for the three months ended March 31, 2019 does not include the impact of the issuance of units in connection with the merger.

XML

Related Party Agreements and Transactions MPC Loan Agreement (Details) - Related Party Revolving Credit Agreement [Member] - MPC Investment [Member] - USD ($) $ in Millions				3 Months Ended	12 Months Ended
		Jul. 31, 2019	Apr. 27, 2018	Mar. 31, 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				$ 1,667	$ 8,540
Line of Credit Facility, Interest Rate During Period				2.833%	3.441%
Repayments of Lines of Credit				$ 2,261	$ 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

Description of Business and Basis of Presentation - Additional Information (Detail) $ in Millions		3 Months Ended	12 Months Ended
	Jul. 30, 2019 shares	Mar. 31, 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
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	$ 1,197
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

XML

Net Income Per Limited Partner Unit - Schedule of Distributions by Partner by Class (Detail) - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Net Income Per Share [Line Items]
Potentially dilutive units		1		1
Net income attributable to MPLX LP		$ (2,724)	[1]	$ 503	[2],[3]
Less: Distribution declared		759		543
Undistributed net income (loss) attributable to MPLX LP		(3,483)		(40)
Undistributed net loss attributable to MPLX LP		(3,483)		(40)
Contributions from:		225		15	[4]
Limited Partners Common Units
Net Income Per Share [Line Items]
Net income attributable to MPLX LP		(2,755)	[1]	483	[3]
Less: Distribution declared	[5]	728		523
Undistributed net income (loss) attributable to MPLX LP		(3,483)		(40)
MPC | Limited Partners Common Units
Net Income Per Share [Line Items]
Contributions from:		225		0	[4]
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP		20	[1]	20	[3]
Less: Distribution declared	[5]	20		20
Undistributed net income (loss) attributable to MPLX LP		0		0
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP	[1]	11
Less: Distribution declared	[5]	11		$ 0
Undistributed net income (loss) attributable to MPLX LP		$ 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 first quarter of 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] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] See Note 7 for distribution information.

XML

Fair Value Measurments - Recurring - Significant Unobservable Inputs in Level 3 Valuation (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.39
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	95.00%
Fair Value Inputs Probability of Renewal Second Term	83.50%
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	$ 0.26
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	$ 0.68

XML

Revenue Contract Balances (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Long-term deferred revenue, beginning balance		$ 217
Long-term deferred revenue, ending balance		241
Liability, change in timeframe, performance obligation satisfied, revenue recognized		0
ASC 606
Contract assets, beginning balance	[1]	39	$ 36
Contract assets, additions/(deletions)		(27)	(17)	[2]
Contract assets, revenue recognized	[3]	0	0	[2]
Contract assets, ending balance		12	19	[2]
Deferred revenue, beginning balance	[1]	23	13
Deferred revenue, additions/(deletions)		5	1	[2]
Deferred revenue, revenue recognized	[3]	(3)	(1)	[2]
Deferred revenue, ending balance		25	13	[2]
Deferred revenue - related parties, beginning balance	[1]	53	65
Deferred revenue - related party, additions/(deletions)		12	9	[2]
Deferred revenue - related parties, revenue recognized	[3]	(16)	(16)	[2]
Deferred revenue - related parties, ending balance		49	58	[2]
Long-term deferred revenue, beginning balance	[1]	90	56
Long-term deferred revenue, additions/(deletions)		6	1	[2]
Long-term deferred revenue, revenue recognized	[3]	0	0	[2]
Long-term deferred revenue, ending balance		96	57	[2]
Long-term deferred revenue - related parties, beginning balance	[1]	55	52
Long-term deferred revenue - related party, additions/(deletions)		1	0	[2]
Long-term deferred revenue - related parties, revenue recognized	[3]	0	0	[2]
Long-term deferred revenue - related parties, ending balance		$ 56	$ 52	[2]

[1] Balance represents ASC 606 portion of each respective line item.

[2] Financial information for the first quarter of 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

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 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.

XML

Derivative Financial Instruments - Derivatives Balance Sheet Location (Details) - Not Designated as Hedging Instrument [Member] - Commodity contracts - USD ($) $ in Millions		Mar. 31, 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]	45	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]	2	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]	$ 43	$ 55

[1] Includes embedded derivatives in commodity contracts as discussed above.

XML

Segment Information

3 Months Ended

Mar. 31, 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 March 31,
(In millions)	2020			2019(1)
L&S
Service revenue	$	1,004		$	889
Rental income	242			335
Product related revenue	19			15
Income from equity method investments	50			45
Other income	51			12
Total segment revenues and other income(2)	1,366			1,296
Segment Adjusted EBITDA(3)	872			559
Capital expenditures	184			198
Investments in unconsolidated affiliates	54			7
G&P
Service revenue	536			528
Rental income	88			89
Product related revenue	222			276
(Loss)/income from equity method investments	(1,234		)	32
Other income	14			14
Total segment revenues and other (loss)/income(2)	(374		)	939
Segment Adjusted EBITDA(3)	422			371
Capital expenditures	134			306
Investments in unconsolidated affiliates	$	37		$	128

(1) Financial information for the first quarter of 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 $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

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

(In millions)	March 31, 2020		December 31, 2019
Segment assets
Cash and cash equivalents	$	57	$	15
L&S	20,891		20,810
G&P	16,058		19,605
Total assets	$	37,006	$	40,430

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

	Three Months Ended March 31,
(In millions)	2020			2019(1)
Reconciliation to Net (loss)/income:
L&S Segment Adjusted EBITDA	$	872		$	559
G&P Segment Adjusted EBITDA	422			371
Total reportable segments	1,294			930
Depreciation and amortization(2)	(325		)	(301		)
Benefit for income taxes	—			1
Amortization of deferred financing costs	(14		)	(7		)
Non-cash equity-based compensation	(5		)	(7		)
Impairment expense	(2,165		)	—
Net interest and other financial costs	(216		)	(217		)
(Loss)/income from equity method investments	(1,184		)	77
Distributions/adjustments related to equity method investments	(124		)	(122		)
Unrealized derivative gains/(losses)(3)	15			(4		)
Acquisition costs	—			(1		)
Other	(1		)	—
Adjusted EBITDA attributable to noncontrolling interests	9			7
Adjusted EBITDA attributable to Predecessor(4)	—			333
Net (loss)/income	$	(2,716	)	$	689

(1) Financial information for the first quarter of 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 $126 million for the three months ended March 31, 2020 and 2019, respectively. Depreciation and amortization attributable to G&P was $187 million and $175 million for the three months ended March 31, 2020 and 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.

XML

Related Party Agreements and Transactions

3 Months Ended

Mar. 31, 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. Activity on the MPC Loan Agreement was as follows:

(In millions)	Three Months Ended March 31, 2020			Year Ended December 31, 2019
Borrowings	$	1,667		$	8,540
Average interest rate of borrowings	2.833		%	3.441		%
Repayments	$	2,261		$	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 March 31,
(In millions)	2020		2019
Service revenues - related parties
MPC	$	927	$	803
Other	1		—
Total Service revenue - related parties	928		803
Rental income - related parties
MPC	234		325
Product sales - related parties(1)
MPC	33		41
Other income - related parties
MPC	48		10
Other	16		16
Total Other income - related parties	$	64	$	26

(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 months ended March 31, 2020, these sales totaled $173 million. For the three months ended March 31, 2019, these sales totaled $223 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 rent and 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 March 31,
(In millions)	2020		2019
Rental cost of sales - related parties
MPC	$	46	$	43
Purchases - related parties
MPC	271		273
Other	5		5
Total Purchase - related parties	276		278
General and administrative expenses
MPC	$	64	$	62

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 months ended March 31, 2020 and 2019, these charges totaled $36 million and $41 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)	March 31, 2020		December 31, 2019
Current assets - related parties
Receivables - MPC	$	538	$	621
Receivables - Other	21		22
Prepaid - MPC	15		9
Lease Receivables - MPC	26		4
Total	600		656
Noncurrent assets - related parties
Long-term receivables - MPC	28		21
Right of use assets - MPC	231		232
Long-term lease receivables - MPC	399		43
Unguaranteed residual asset - MPC	19		7
Total	677		303
Current liabilities - related parties
Payables - MPC	227		911
Payables - Other	16		37
Operating lease liabilities - MPC	1		1
Deferred revenue - Minimum volume deficiencies - MPC	38		42
Deferred revenue - Project reimbursements - MPC	14		16
Deferred revenue - Project reimbursements - Other	1		1
Total	297		1,008
Long-term liabilities - related parties
Long-term operating lease liabilities - MPC	230		230
Long-term deferred revenue - Project reimbursements - MPC	54		53
Long-term deferred revenue - Project reimbursements - Other	6		7
Total	$	290	$	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 three months ended March 31, 2020 and 2019.

XML

Description of the Business and Basis of Presentation Accounting Policies (Policies)

3 Months Ended

Mar. 31, 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 recent 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 the midstream services we provide. 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 our 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 have continued to refine and update production forecasts in response to the current environment, which has 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.

(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 months ended March 31, 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.

XML

Net Income Per Limited Partner Unit (Tables)

3 Months Ended

Mar. 31, 2020

Earnings Per Share [Abstract]

Schedule of Distributions By Partner By Class

For the three months ended March 31, 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 months ended March 31, 2020 and 2019 were 1 million and less than 1 million, respectively.

	Three Months Ended March 31,
(In millions)	2020			2019
Net income attributable to MPLX LP	$	(2,724	)	$	503
Less: Distributions declared on Series A preferred units(1)	20			20
Distributions declared on Series B preferred units(1)	11			—
Limited partners’ distributions declared on MPLX common units (including common units of general partner)(1)	728			523
Undistributed net loss attributable to MPLX LP	$	(3,483	)	$	(40	)

(1)

See Note 7 for distribution information.

Schedule of Basic and Diluted Earnings Per Unit

	Three Months Ended March 31, 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	$	728		$	20	$	11	$	759
Undistributed net loss attributable to MPLX LP	(3,483		)	—		—		(3,483		)
Net income attributable to MPLX LP(1)	$	(2,755	)	$	20	$	11	$	(2,724	)
Weighted average units outstanding:
Basic	1,058
Diluted	1,058
Net income attributable to MPLX LP per limited partner unit:
Basic	$	(2.60	)
Diluted	$	(2.60	)

(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 March 31, 2019
(In millions, except per unit data)	Limited Partners’ Common Units			Series A Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	523		$	20	$	543
Undistributed net loss attributable to MPLX LP	(40		)	—		(40		)
Net income attributable to MPLX LP(1)	$	483		$	20	$	503
Weighted average units outstanding:
Basic	794
Diluted	795
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.61
Diluted	$	0.61

(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.

XML

Inventories (Tables)

3 Months Ended

Mar. 31, 2020

Inventory Disclosure [Abstract]

Summary of Inventories

Inventories consist of the following:

(In millions)	March 31, 2020		December 31, 2019
NGLs	$	1	$	5
Line fill	6		10
Spare parts, materials and supplies	98		95
Total inventories	$	105	$	110

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
		Mar. 31, 2020		Mar. 31, 2019
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		$ (3,483)		$ (40)
Net income attributable to MPLX LP		(2,724)	[1]	503	[2],[3]
Limited Partners Common Units
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		(3,483)		(40)
Net income attributable to MPLX LP		$ (2,755)	[1]	$ 483	[3]
Weighted average units outstanding:
Common - basic (in shares)		1,058		794	[2]
Common - diluted (in shares)		1,058		795	[2]
Net income attributable to MPLX LP per limited partner unit:
Basic (in USD per unit)		$ (2.60)		$ 0.61	[2]
Diluted (in USD per unit)		$ (2.60)		$ 0.61	[2]
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		$ 0		$ 0
Net income attributable to MPLX LP		20	[1]	$ 20	[3]
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Net income (loss) attributable to MPLX LP:
Undistributed net income (loss) attributable to MPLX LP		0
Net income attributable to MPLX LP	[1]	$ 11

[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 first quarter of 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.

XML

Sales to Related Parties (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Related Party Transaction [Line Items]
Rental income - related parties		$ 234	$ 325	[1]
Other income - related parties		64	26	[1]
MPC
Related Party Transaction [Line Items]
Rental income - related parties		234	325
Other income - related parties		48	10
Product sales to MPC that net to zero		173	223
Other Affiliates [Member]
Related Party Transaction [Line Items]
Other income - related parties		16	16
Product [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		33	41	[1],[2]
Product [Member] | MPC
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	[3]	33	41
Service [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		928	803	[1],[2]
Service [Member] | MPC
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		927	803
Service [Member] | Other Affiliates [Member]
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		$ 1	$ 0

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the first quarter of 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 months ended March 31, 2020, these sales totaled $173 million. For the three months ended March 31, 2019, these sales totaled $223 million.

XML

Accounting Standards Impact of Adoption (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Receivables, net	$ 522	$ 593
Accounts Receivable, Allowance for Credit Loss	$ 1

XML

Fair Value Measurements - Recurring - Financial Instruments by Valuation Hierarchy (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset	$ 0	$ 0
Derivative liability	45	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	$ 45	$ 60

XML

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,781	$ 1,708	[1]
Operating Income (Loss)	[2]	(789)	527	[1]
Total segment revenues and other income		992	2,235	[1],[3]
L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,023	904	[1]
G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		758	804	[1]
Service [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		612	614	[1],[3]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		928	803	[1],[3]
Service [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		84	86	[1]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		920	803	[1]
Service [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		528	528	[1]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		8	0	[1]
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		39	34	[1],[3]
Service, Other [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	[1]
Service, Other [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		39	34	[1]
Product [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		169	216	[3]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		33	41	[1],[3]
Revenue from Contract with Customer, excluding Assessed Tax and Non-ASC 606 Revenue	[2]	169	216	[1]
Product [Member] | L&S
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		4	4	[1]
Revenue from Contract with Customer, excluding Assessed Tax and Non-ASC 606 Revenue		15	11	[1]
Product [Member] | G&P
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		29	37	[1]
Revenue from Contract with Customer, excluding Assessed Tax and Non-ASC 606 Revenue	[2]	$ 154	$ 205	[1]

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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

[3] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Supplemental Cash Flow Information - Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
(Decrease)/increase in capital accruals	$ (61)	$ (71)

XML

Derivative Financial Instruments - Embedded Derivatives in Commodity Contracts (Details) - Natural Gas [Member] - Embedded derivatives in commodity contracts $ in Millions	3 Months Ended
	Mar. 31, 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	$ 45	$ 60

XML

Goodwill and Intangibles (Tables)

3 Months Ended

Mar. 31, 2020

Finite-Lived Intangible Assets [Line Items]

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

Gross intangible assets with accumulated amortization as of March 31, 2020 and December 31, 2019 is shown below:

		March 31, 2020							December 31, 2019
(In millions)	Useful Life	Gross		Accumulated Amortization(1)(2)			Net		Gross		Accumulated Amortization			Net
L&S	6 - 8 years	$	283	$	(54	)	$	229	$	283	$	(45	)	$	238
G&P	6 - 25 years	1,288		(462		)	826		1,288		(256		)	1,032
		$	1,571	$	(516	)	$	1,055	$	1,571	$	(301	)	$	1,270

(1) Amortization expense attributable to the G&P and L&S segments for the three months ended March 31, 2020 was $29 million and $9 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 March 31, 2020 is as follows:

(In millions)
2020	$	96
2021	128
2022	128
2023	128
2024	124
Thereafter	451
Total	$	1,055

XML

Debt (Tables)

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Summary of Outstanding Borrowings

MPLX’s outstanding borrowings consist of the following:

(In millions)	March 31, 2020			December 31, 2019
MPLX LP:
Bank revolving credit facility	$	750		$	—
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)	14			19
Total	20,864			20,119
Unamortized debt issuance costs	(103		)	(106		)
Unamortized discount/premium	(290		)	(300		)
Amounts due within one year	(4		)	(9		)
Total long-term debt due after one year	$	20,467		$	19,704

(1)    See Note 20 for lease information.

XML

Equity-Based Compensation Plan (Tables)

3 Months Ended

Mar. 31, 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 three months ended March 31, 2020:

	Number of Units		Weighted Average Fair Value
Outstanding at December 31, 2019	1,109,568		$	35.97
Granted	168,212		20.49
Settled	(174,888	)	36.29
Forfeited	(335	)	33.55
Outstanding at March 31, 2020	1,102,557		$	33.56

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 three months ended March 31, 2020:

	Number of Units
Outstanding at December 31, 2019	2,157,347
Granted	2,147,211
Settled	(1,169,354	)
Forfeited	(18,750	)
Outstanding at March 31, 2020	3,116,454

XML

Segment Information - Reconciliation to Net Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization	[1]	$ (325)		$ (301)	[2],[3],[4]
Income Tax Expense (Benefit)		0		1	[3],[4]
Amortization of Debt Issuance Costs		(14)		(7)	[2]
Share-based Payment Arrangement, Expense		(5)		(7)	[4]
Goodwill and Intangible Asset Impairment		(2,165)		0	[2],[3],[4]
Interest and Other Financial Costs		(216)		(217)	[4]
Income/(loss) from equity method investments(2)		(1,184)	[5],[6],[7]	77	[2],[3],[4],[8]
Proceeds from Equity Method Investment, Distribution, Return of Capital		(119)		(115)	[2]
Acquisition Costs, Period Cost		0		(1)	[4]
Other Cost and Expense, Operating		1		0	[4]
Net income		(2,716)		689	[2],[3],[4],[9]
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA		1,294		930	[4]
Amortization of Debt Issuance Costs		(14)		(7)	[4]
Segment Reconciling Items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Proceeds from Equity Method Investment, Distribution, Return of Capital		(124)		(122)	[4]
Adjusted EBITDA attributable to noncontrolling interests		9		7	[4]
L&S
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		138		126
L&S | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[10]	872		559	[4]
Income/(loss) from equity method investments(2)		50		45	[4]
G&P
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		187		175
G&P | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[10]	422		371	[4]
Income/(loss) from equity method investments(2)		(1,234)		32	[4]
Not Designated as Hedging Instrument [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	[10]	$ 15		$ (4)	[4]

[1] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the first quarter of 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 2020 period includes $1,264 million of impairment expense. See Note 4.

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

[8] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[9] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[10] See below for the reconciliation from Segment Adjusted EBITDA to net income.

XML

Leases Lessor Lease Revenues (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	[2]
MPC
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	[1]	$ 186	$ 279
Sales-type Lease, Interest Income		38
Sales-type Lease, Variable Lease Income		0
Third Party [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	[1]	$ 63	$ 65

[1] These amounts are presented net of executory costs.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Series A Preferred Units (Rollforward of Redeemable Preferred Units) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	[1]
Redeemable Noncontrolling Interest [Line Items]
Balance at December 31, 2019	$ 968
Distributions to unitholders and general partner	(717)	$ (515)
Balance at March 31, 2020	968
Series A Convertible Preferred Units
Redeemable Noncontrolling Interest [Line Items]
Balance at December 31, 2019	968
Net income allocated	20
Distributions to unitholders and general partner	(20)
Balance at March 31, 2020	$ 968

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

XML

Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Mar. 31, 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

XML

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Equity Method Investment, Other than Temporary Impairment		$ 1,264
Revenues and other income:
Total revenues from contracts with customers		1,781		$ 1,708	[1]
Rental income		96		99	[2]
Rental income - related parties		234		325	[2]
Income/(loss) from equity method investments(2)		(1,184)	[3],[4],[5]	77	[2],[6],[7],[8]
Other income		1		0	[2]
Other income - related parties		64		26	[2]
Revenues		992		2,235	[1],[2]
Costs and expenses:
Rental cost of sales		35		37	[2]
Rental cost of sales - related parties		46		43	[2]
Purchases - related parties		276		278	[2]
Depreciation and amortization	[9]	325		301	[2],[6],[7]
General and administrative expenses		97		101	[2]
Other taxes		31		30	[2]
Total costs and expenses		3,478		1,323	[2]
Income/(loss) from operations		(2,486)		912	[2]
Related party interest and other financial costs		3		1	[2]
Interest expense (net of amounts capitalized of $13 million and $11 million, respectively)		211		214	[2]
Other financial costs		16		9	[2]
Income/(loss) before income taxes		(2,716)		688	[2]
(Benefit)/provision for income taxes		0		(1)	[2],[7]
Net income		(2,716)		689	[2],[6],[7],[10]
Less: Net income (loss) attributable to noncontrolling interest		8		6	[2]
Income (Loss) Attributable to Predecessor		0		180	[2]
Net income (loss) attributable to MPLX LP		(2,724)	[11]	503	[2],[12]
Limited partners' interest in net income (loss) attributable to MPLX LP		(2,755)		483	[2]
Weighted average limited partner units outstanding:
Goodwill and Intangible Asset Impairment		2,165		0	[2],[6],[7]
Limited Partners Common Units
Costs and expenses:
Net income (loss) attributable to MPLX LP		$ (2,755)	[11]	$ 483	[12]
Net income (loss) attributable to MPLX LP per limited partner unit:
Common - basic (in USD per unit)		$ (2.60)		$ 0.61	[2]
Common - diluted (in USD per unit)		$ (2.60)		$ 0.61	[2]
Weighted average limited partner units outstanding:
Common - basic (in shares)		1,058		794	[2]
Common - diluted (in shares)		1,058		795	[2]
Service [Member]
Revenues and other income:
Total revenues from contracts with customers		$ 612		$ 614	[1],[2]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		928		803	[1],[2]
Service, Other [Member]
Revenues and other income:
Total revenues from contracts with customers		39		34	[1],[2]
Product [Member]
Revenues and other income:
Total revenues from contracts with customers		169		216	[2]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		33		41	[1],[2]
Oil and Gas, Refining and Marketing [Member]
Costs and expenses:
Cost of Goods and Services Sold		368		339	[2]
Natural Gas, Midstream [Member]
Costs and expenses:
Cost of Goods and Services Sold		135		194	[2]
Series A Preferred Stock [Member] | Preferred Partner [Member]
Costs and expenses:
Net income (loss) attributable to MPLX LP		20	[11]	20	[12]
Dividends, Preferred Stock		20		20	[2]
Series B Preferred Stock [Member] | Preferred Partner [Member]
Costs and expenses:
Net income (loss) attributable to MPLX LP	[11]	11
Dividends, Preferred Stock		$ 11		$ 0	[2]

[1] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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

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

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

[6] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[7] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[8] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[9] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $153 million for the three months ended March 31, 2020 and 2019, respectively. Third party losses for the G&P segment were $425 million for the three months ended March 31, 2020 and third party revenues were $887 million for the three months ended March 31, 2019.

[10] Financial information for the first quarter of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[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.

XML

Commitments and Contingencies

3 Months Ended

Mar. 31, 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 March 31, 2020 and December 31, 2019, accrued liabilities for remediation totaled $17 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 March 31, 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 that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system, 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 ordered the U.S. Army Corps of Engineers, 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. If the permit is vacated pending completion of the EIS and the vacatur is deemed temporary, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes while the pipeline is shutdown and 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 court vacates the permit and such action 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, if any. As of March 31, 2020, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $230 million.

Contractual Commitments and Contingencies – At March 31, 2020, MPLX’s contractual commitments to acquire property, plant and equipment totaled $318 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 March 31, 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.

XML

Supplemental Cash Flow Information

3 Months Ended

Mar. 31, 2020

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information [Text Block]

Supplemental Cash Flow Information

	Three Months Ended March 31,
(In millions)	2020			2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	210		$	173
Non-cash investing and financing activities:
Net transfers of property, plant and equipment from (to) 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:

	Three Months Ended March 31,
(In millions)	2020			2019
(Decrease)/increase in capital accruals	$	(61	)	$	(71	)

XML

Fair Value Measurements

3 Months Ended

Mar. 31, 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 March 31, 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.

	March 31, 2020					December 31, 2019
(In millions)	Assets		Liabilities			Assets		Liabilities
Significant unobservable inputs (Level 3)
Embedded derivatives in commodity contracts	$	—	$	(45	)	$	—	$	(60	)
Total carrying value on Consolidated Balance Sheets	$	—	$	(45	)	$	—	$	(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 $0.26 to $0.68 per gallon with a weighted average of $0.39 per gallon per the

current term of the embedded derivative and (2) the probability of renewal of 95 percent for the first five-year term and 83.5 percent for the second five-year term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. An increase in the probability of renewal would result in an increase in the fair value of the related embedded derivative liability. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of March 31, 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 March 31, 2020					Three Months Ended March 31, 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)	—		14			—		(6		)
Settlements	—		1			—		2
Fair value at end of period	—		(45		)	—		(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	$	—	$	13		$	—	$	(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:

	March 31, 2020				December 31, 2019
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Long-term debt	$	18,352	$	20,560	$	21,054	$	19,800
SMR liability	$	77	$	79	$	90	$	80