10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 _____________________________________________

FORM 10-Q

 ____________________________________________

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

For the quarterly period ended June 30, 2022

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 1,012,204,900 common units outstanding at July 29, 2022.

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 and Series A Preferred Units (Unaudited)	7
Notes to Consolidated Financial Statements (Unaudited)	8
Item 2.   Management’s Discussion and Analysis of Financial Condition and Results of Operations	26
Item 3.   Quantitative and Qualitative Disclosures about Market Risk	46
Item 4.   Controls and Procedures	46
PART II – OTHER INFORMATION
Item 1.    Legal Proceedings	48
Item 1A. Risk Factors	48
Item 2.    Unregistered Sales of Equity Securities and Use of Proceeds	48
Item 6.    Exhibits	49
Signatures	51

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
Barrel	One stock tank barrel, or 42 U.S. gallons of liquid volume, used in reference to crude oil or other liquid hydrocarbons
Btu	One British thermal unit, an energy measurement
DCF (a non-GAAP financial measure)	Distributable Cash Flow
EBITDA (a non-GAAP financial measure)	Earnings Before Interest, Taxes, Depreciation and Amortization
GAAP	Accounting principles generally accepted in the United States of America
G&P	Gathering and Processing segment
LIBOR	London Interbank Offered Rate
L&S	Logistics and Storage segment
mbpd	Thousand barrels per day
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
SEC	U.S. Securities and Exchange Commission
SOFR	Secured Overnight Financing Rate
VIE	Variable interest entity

2

Part I—Financial Information

Item 1. Financial Statements

MPLX LP

Consolidated Statements of Income (Unaudited)

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per unit data)	2022		2021		2022		2021
Revenues and other income:
Service revenue	$	577	$	578	$	1,131	$	1,167
Service revenue - related parties	938		907		1,853		1,779
Service revenue - product related	118		76		241		153
Rental income	102		99		193		198
Rental income - related parties	198		168		363		410
Product sales	698		304		1,195		586
Product sales - related parties	51		31		96		73
Sales-type lease revenue - related parties	114		136		225		173
Income from equity method investments	111		66		210		136
Other income (loss)	6		3		(11)		4
Other income - related parties	27		27		54		55
Total revenues and other income	2,940		2,395		5,550		4,734
Costs and expenses:
Cost of revenues (excludes items below)	323		293		610		566
Purchased product costs	663		338		1,130		614
Rental cost of sales	42		32		79		64
Rental cost of sales - related parties	19		23		34		62
Purchases - related parties	351		297		670		595
Depreciation and amortization	310		318		623		647
Impairment expense	—		42		—		42
General and administrative expenses	82		87		160		173
Other taxes	33		34		67		66
Total costs and expenses	1,823		1,464		3,373		2,829
Income from operations	1,117		931		2,177		1,905
Related party interest and other financial costs	1		2		5		2
Interest expense (net of amounts capitalized of $3 million, $5 million, $5 million and $10 million respectively)	212		195		410		393
Other financial costs	20		19		40		46
Income before income taxes	884		715		1,722		1,464
Provision for income taxes	—		—		5		1
Net income	884		715		1,717		1,463
Less: Net income attributable to noncontrolling interests	9		9		17		18
Net income attributable to MPLX LP	875		706		1,700		1,445
Less: Series A preferred unitholders interest in net income	21		21		42		41
Less: Series B preferred unitholders interest in net income	10		10		21		21
Limited partners’ interest in net income attributable to MPLX LP	$	844	$	675	$	1,637	$	1,383
Per Unit Data (See Note 6)
Net income attributable to MPLX LP per limited partner unit:
Common - basic	$	0.83	$	0.66	$	1.61	$	1.34
Common - diluted	$	0.83	$	0.66	$	1.61	$	1.34
Weighted average limited partner units outstanding:
Common - basic	1,012		1,029		1,013		1,033
Common - diluted	1,012		1,029		1,014		1,033

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

3

MPLX LP

Consolidated Statements of Comprehensive Income (Unaudited)

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Net income	$	884	$	715	$	1,717	$	1,463
Other comprehensive income, net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	—		—		9		(2)
Comprehensive income	884		715		1,726		1,461
Less comprehensive income attributable to:
Noncontrolling interests	9		9		17		18
Comprehensive income attributable to MPLX LP	$	875	$	706	$	1,709	$	1,443

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

4

MPLX LP

Consolidated Balance Sheets (Unaudited)

 

(In millions)	June 30, 2022		December 31, 2021
Assets
Current assets:
Cash and cash equivalents	$	298	$	13
Receivables, net	789		654
Current assets - related parties	731		644
Inventories	157		142
Other current assets	43		54
Total current assets	2,018		1,507
Equity method investments	4,099		3,981
Property, plant and equipment, net	19,767		20,042
Intangibles, net	768		831
Goodwill	7,645		7,657
Right of use assets, net	300		268
Noncurrent assets - related parties	1,142		1,161
Other noncurrent assets	49		60
Total assets	35,788		35,507
Liabilities
Current liabilities:
Accounts payable	352		172
Accrued liabilities	415		363
Current liabilities - related parties	403		1,780
Accrued property, plant and equipment	104		97
Long-term debt due within one year	1,000		499
Accrued interest payable	224		202
Operating lease liabilities	45		59
Other current liabilities	198		176
Total current liabilities	2,741		3,348
Long-term deferred revenue	429		383
Long-term liabilities - related parties	303		302
Long-term debt	18,775		18,072
Deferred income taxes	14		10
Long-term operating lease liabilities	250		205
Other long-term liabilities	167		170
Total liabilities	22,679		22,490
Commitments and contingencies (see Note 15)
Series A preferred units (30 million and 30 million units issued and outstanding)	965		965
Equity
Common unitholders - public (365 million and 369 million units issued and outstanding)	8,518		8,579
Common unitholders - MPC (647 million and 647 million units issued and outstanding)	2,784		2,638
Series B preferred units (0.6 million and 0.6 million units issued and outstanding)	611		611
Accumulated other comprehensive loss	(8)		(17)
Total MPLX LP partners’ capital	11,905		11,811
Noncontrolling interests	239		241
Total equity	12,144		12,052
Total liabilities, preferred units and equity	$	35,788	$	35,507

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

5

MPLX LP

Consolidated Statements of Cash Flows (Unaudited)

	Six Months Ended June 30,
(In millions)	2022		2021
Operating activities:
Net income	$	1,717	$	1,463
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs	36		35
Depreciation and amortization	623		647
Impairment expense	—		42
Deferred income taxes	4		(1)
Loss on disposal of assets	16		1
Income from equity method investments	(210)		(136)
Distributions from unconsolidated affiliates	258		239
Change in fair value of derivatives	(16)		39
Changes in:
Current receivables	(131)		(83)
Inventories	(15)		(8)
Current accounts payable and accrued liabilities	253		77
Current assets/current liabilities - related parties	—		101
Right of use assets/operating lease liabilities	—		1
Deferred revenue	41		43
All other, net	36		29
Net cash provided by operating activities	2,612		2,489
Investing activities:
Additions to property, plant and equipment	(294)		(235)
Acquisitions, net of cash acquired	(28)		—
Disposal of assets	67		74
Investments in unconsolidated affiliates	(156)		(84)
Net cash used in investing activities	(411)		(245)
Financing activities:
Long-term debt - borrowings	2,385		2,800
- repayments	(1,201)		(3,746)
Related party debt - borrowings	2,824		4,435
- repayments	(4,274)		(3,942)
Debt issuance costs	(16)		—
Unit repurchases	(135)		(310)
Distributions to noncontrolling interests	(19)		(20)
Distributions to Series A preferred unitholders	(42)		(41)
Distributions to Series B preferred unitholders	(21)		(21)
Distributions to unitholders and general partner	(1,430)		(1,421)
Contributions from MPC	17		17
All other, net	(4)		(2)
Net cash used in financing activities	(1,916)		(2,251)
Net increase/ (decrease) in cash, cash equivalents and restricted cash	285		(7)
Cash, cash equivalents and restricted cash at beginning of period	13		15
Cash, cash equivalents and restricted cash at end of period	$	298	$	8

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

6

MPLX LP

Consolidated Statements of Equity and Series A Preferred Units (Unaudited)

	Partnership
(In millions)	Common Unit-holders Public		Common Unit-holder MPC		Series B Preferred Unit-holders		Accumulated Other Comprehensive Loss		Non-controlling Interests		Total		Series A Preferred Unit-holders
Balance at December 31, 2020	$	9,384	$	2,792	$	611	$	(15)	$	245	$	13,017	$	968
Net income	266		443		11		—		9		729		20
Unit repurchases	(155)		—		—		—		—		(155)		—
Distributions	(269)		(445)		(21)		—		(10)		(745)		(20)
Contributions	—		7		—		—		—		7		—
Other	—		(1)		—		(2)		—		(3)		—
Balance at March 31, 2021	9,226		2,796		601		(17)		244		12,850		968
Net income	251		423		10		—		9		693		21
Unit repurchases	(155)		—		—		—		—		(155)		—
Distributions	(262)		(445)		—		—		(10)		(717)		(21)
Contributions	—		122		—		—		—		122		—
Other	1		1		—		—		—		2		—
Balance at June 30, 2021	$	9,061	$	2,897	$	611	$	(17)	$	243	$	12,795	$	968
Balance at December 31, 2021	$	8,579	$	2,638	$	611	$	(17)	$	241	$	12,052	$	965
Net income	287		506		11		—		8		812		21
Unit repurchases	(100)		—		—		—		—		(100)		—
Distributions	(260)		(456)		(21)		—		(9)		(746)		(21)
Contributions	—		10		—		—		—		10		—
Other	(1)		—		—		9		—		8		—
Balance at March 31, 2022	8,505		2,698		601		(8)		240		12,036		965
Net income	304		540		10		—		9		863		21
Unit repurchases	(35)		—		—		—		—		(35)		—
Distributions	(257)		(457)		—		—		(10)		(724)		(21)
Contributions	—		2		—		—		—		2		—
Other	1		1		—		—		—		2		—
Balance at June 30, 2022	$	8,518	$	2,784	$	611	$	(8)	$	239	$	12,144	$	965

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 gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the 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, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

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 information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2021. The results of operations for the three and six months ended June 30, 2022 are not necessarily indicative of the results to be expected for the full year.

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.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

2. Accounting Standards

Recently Adopted

ASU 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance

In November 2021, the FASB issued guidance requiring disclosures for certain types of government assistance that have been accounted for by analogy to grant or contribution models. Disclosures will include information about the type of transactions, accounting and the impact on financial statements. MPLX prospectively adopted this standard in the first quarter of 2022. The adoption of this standard did not have a material impact on our financial statements or disclosures.

8

3. Investments and Noncontrolling Interests

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

	Ownership as of	Carrying value at
	June 30,	June 30,		December 31,
(In millions, except ownership percentages)	2022	2022		2021
L&S
MarEn Bakken Company LLC(1)	25%	$	493	$	449
Illinois Extension Pipeline Company, L.L.C.	35%	244		243
LOOP LLC	41%	278		265
Andeavor Logistics Rio Pipeline LLC(2)	67%	180		183
Minnesota Pipe Line Company, LLC	17%	182		183
Whistler Pipeline LLC(2)	38%	174		155
Explorer Pipeline Company	25%	59		66
W2W Holdings LLC(2)	50%	59		58
Other(2)		136		116
Total L&S		1,805		1,718
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	683		680
Sherwood Midstream LLC(2)	50%	535		544
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	339		332
MarkWest Torñado GP, L.L.C.(2)	60%	286		246
Rendezvous Gas Services, L.L.C.(2)	78%	143		147
Sherwood Midstream Holdings LLC(2)	51%	130		136
Centrahoma Processing LLC	40%	134		133
Other(2)		44		45
Total G&P		2,294		2,263
Total		$	4,099	$	3,981

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

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

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

Sherwood Midstream LLC (“Sherwood Midstream”) has been deemed the primary beneficiary of Sherwood Midstream Holdings LLC (“Sherwood Midstream Holdings”) due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. Therefore, MPLX also reports its portion of Sherwood Midstream Holdings’ net assets as a component of its investment in Sherwood Midstream. As of June 30, 2022, MPLX has a 24.55 percent indirect ownership interest in Sherwood Midstream Holdings through Sherwood Midstream.

MPLX’s maximum exposure to loss as a result of its involvement with equity method investments includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. MPLX did not provide any financial support to equity method investments that it was not contractually obligated to provide during the six months ended June 30, 2022.

9

Summarized financial information for MPLX’s equity method investments for the six months ended June 30, 2022 and 2021 is as follows:

	Six Months Ended June 30, 2022
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	550	$	637	$	1,187
Costs and expenses	299		279		578
Income from operations	251		358		609
Net income	227		328		555
Income from equity method investments	$	124	$	86	$	210

	Six Months Ended June 30, 2021
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	336	$	607	$	943
Costs and expenses	217		284		501
Income from operations	119		323		442
Net income	105		283		388
Income from equity method investments	$	73	$	63	$	136

Summarized balance sheet information for MPLX’s equity method investments as of June 30, 2022 and December 31, 2021 is as follows:

	June 30, 2022
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	363	$	394	$	757
Noncurrent assets	7,583		5,062		12,645
Current liabilities	292		249		541
Noncurrent liabilities	$	2,464	$	805	$	3,269

	December 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	335	$	411	$	746
Noncurrent assets	7,439		4,895		12,334
Current liabilities	217		310		527
Noncurrent liabilities	$	2,461	$	788	$	3,249

4. 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, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products, 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 agreements.

On June 30, 2022, MPLX and MPC entered into a Master Amendment to Transportation Services Agreements (“Master Amendment”). The Master Amendment extends the term of six transportation services agreements through 2032 and provides

10

for automatic renewals of up to two additional five-year terms, subject to either party providing written notice at least six months prior to the end of the then-current term.

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 extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC Investment. The borrowing capacity of the MPC Loan Agreement is $1.5 billion aggregate principal amount of all loans outstanding at any one time. The loan agreement is scheduled to expire, and borrowings under the loan agreement are scheduled to mature and 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 maturity. Borrowings under the MPC Loan Agreement bear interest at LIBOR plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 11.

Activity on the MPC Loan Agreement was as follows:

	Six Months Ended June 30,
(In millions)	2022			2021
Borrowings	$	2,824		$	4,435
Average interest rate of borrowings	1.458		%	1.354		%
Repayments	$	4,274		$	3,942
Outstanding balance at end of period	$	—		$	493

Related Party Revenue

Related party sales to MPC primarily consist of crude oil and refined products pipeline and trucking transportation services based on tariff or 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. These agreements are classified as Other income - related parties on the Consolidated Statements of Income.

Certain product sales to MPC net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and six months ended June 30, 2022, these sales totaled $281 million and $574 million, respectively. For the three and six months ended June 30, 2021, these sales totaled $177 million and $345 million, respectively.

Related Party Expenses

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

For the three and six months ended June 30, 2022, General and administrative expenses incurred from MPC totaled $58 million and $113 million, respectively. For the three and six months ended June 30, 2021, General and administrative expenses incurred from MPC totaled $63 million and $120 million, respectively.

Some charges incurred under the omnibus and ESA agreements are related to engineering services and are associated with assets under construction. These charges are added to Property, plant and equipment, net on the Consolidated Balance Sheets. For the three and six months ended June 30, 2022, these charges totaled $19 million and $38 million, respectively. For the three and six months ended June 30, 2021, these charges totaled $15 million and $27 million, respectively.

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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 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 received under these agreements (excluding payments received under agreements classified as sales-type leases) 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. Deficiency payments under agreements that have been classified as sales-type leases are recorded as a reduction against the corresponding lease receivable. In addition, capital projects MPLX undertakes at the request of MPC are reimbursed in cash and recognized as revenue over the remaining term of the applicable agreements or in some cases, as a contribution from MPC.

(In millions)	June 30, 2022		December 31, 2021
Current assets - related parties
Receivables	$	628	$	555
Prepaid	10		4
Other	2		3
Lease receivables	91		82
Total	731		644
Noncurrent assets - related parties
Long-term receivables	27		31
Right of use assets	229		229
Long-term lease receivables	822		854
Unguaranteed residual asset	64		47
Total	1,142		1,161
Current liabilities - related parties
MPC loan agreement and other payables(1)	329		1,702
Operating lease liabilities	1		1
Deferred revenue - Minimum volume deficiencies	32		35
Deferred revenue - Project reimbursements	41		42
Total	403		1,780
Long-term liabilities - related parties
Long-term operating lease liabilities	228		228
Long-term deferred revenue - Project reimbursements	75		74
Total	$	303	$	302

(1)    Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in Current liabilities - related parties on the Consolidated Balance Sheets. There were no borrowings outstanding on the intercompany loan with MPC as of June 30, 2022.

5. Equity

The changes in the number of common units during the six months ended June 30, 2022 are summarized below:

(In units)	Common Units
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	183,478
Units redeemed in unit repurchase program	(4,156,956)
Balance at June 30, 2022	1,012,204,900

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Unit Repurchase Program

On November 2, 2020, MPLX announced the board authorization of a unit repurchase program for the repurchase of up to $1 billion of MPLX’s outstanding common units held by the public.

Total unit repurchases were as follows for the respective periods:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per unit data)	2022		2021		2022		2021
Number of common units repurchased	1		6		4		12
Cash paid for common units repurchased	$	35	$	155	$	135	$	310
Average cost per unit	$	33.74	$	27.40	$	32.48	$	26.02

As of June 30, 2022, we had $202 million remaining under the existing unit repurchase authorization. On August 2, 2022, MPLX announced the board of directors approved an incremental $1 billion unit repurchase authorization. The unit repurchase authorizations have no expiration date. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, accelerated unit repurchases, tender offers or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing of repurchases will depend upon several factors, including market and business conditions, and repurchases may be discontinued at any time.

Series B Preferred Units

MPLX has 600,000 outstanding units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of MPLX with a price to the public of $1,000 per unit (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. Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, 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, in each case assuming a distribution is declared by the Board of Directors. MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023 at the Series B preferred unit redemption price of $1,000 per unit, plus any accumulated and unpaid distributions up to the redemption date.

Cash distributions

On July 26, 2022, MPLX declared a cash distribution for the second quarter of 2022, totaling $714 million, or $0.7050 per common unit. This distribution will be paid on August 12, 2022 to common unitholders of record on August 5, 2022. This rate will also be received by Series A preferred unitholders.

Quarterly distributions for 2022 and 2021 are summarized below:

(Per common unit)	2022		2021
March 31,	$	0.7050	$	0.6875
June 30,	0.7050		0.6875

In accordance with the distribution rights discussed above, MPLX will make a cash distribution totaling $21 million to Series B unitholders on August 15, 2022.

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and six months ended June 30, 2022 and 2021. Distributions, although earned, are not accrued until declared. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the

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distributions were earned.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	714	$	705	$	1,427	$	1,412
Series A preferred unit distributions	21		21		42		41
Series B preferred unit distributions	10		10		21		21
Total cash distributions declared	$	745	$	736	$	1,490	$	1,474

6. Net Income Per Limited Partner Unit

Net income per unit applicable to common units is computed by dividing net income attributable to MPLX LP less income allocated to participating securities by the weighted average number of common units outstanding.

During the three and six months ended June 30, 2022 and 2021, MPLX had participating securities consisting of common units, certain equity-based compensation awards, Series A preferred units and Series B preferred units and had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three and six months ended June 30, 2022 and 2021 were less than 1 million.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Net income attributable to MPLX LP	$	875	$	706	$	1,700	$	1,445
Less: Distributions declared on Series A preferred units	21		21		42		41
Distributions declared on Series B preferred units	10		10		21		21
Limited partners’ distributions declared on MPLX common units (including common units of general partner)	714		705		1,427		1,412
Undistributed net gain/ (loss) attributable to MPLX LP	$	130	$	(30)	$	210	$	(29)

	Three Months Ended June 30, 2022
(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	$	714	$	21	$	10	$	745
Undistributed net gain attributable to MPLX LP	126		$	4	—		130
Net income attributable to MPLX LP(1)	$	840	$	25	$	10	$	875
Weighted average units outstanding:
Basic	1,012
Diluted	1,012
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.83
Diluted	$	0.83

(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.

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	Three Months Ended June 30, 2021
(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	$	705	$	21	$	10	$	736
Undistributed net loss attributable to MPLX LP	(30)		—		—		(30)
Net income attributable to MPLX LP(1)	$	675	$	21	$	10	$	706
Weighted average units outstanding:
Basic	1,029
Diluted	1,029
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.66
Diluted	$	0.66

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

	Six Months Ended June 30, 2022
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,427	$	42	$	21	$	1,490
Undistributed net gain attributable to MPLX LP	204		6		—		210
Net income attributable to MPLX LP(1)	$	1,631	$	48	$	21	$	1,700
Weighted average units outstanding:
Basic	1,013
Diluted	1,014
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.61
Diluted	$	1.61

(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.

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	Six Months Ended June 30, 2021
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,412	$	41	$	21	$	1,474
Undistributed net loss attributable to MPLX LP	(29)		—		—		(29)
Net income attributable to MPLX LP(1)	$	1,383	$	41	$	21	$	1,445
Weighted average units outstanding:
Basic	1,033
Diluted	1,033
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.34
Diluted	$	1.34

(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. 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 – gathers, transports, stores and distributes crude oil, refined products, and other hydrocarbon-based products. Also includes the operation of refining logistics, fuels distribution and inland marine businesses, terminals, rail facilities, and storage caverns.

•G&P – gathers, processes and transports natural gas; and 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) interest and other financial costs; (iii) impairment expense; (iv) income/(loss) from equity method investments; (v) distributions and adjustments related to equity method investments; (vi) noncontrolling interests; and (vii) 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. Assets by segment are not a measure used to assess the performance of the Partnership by our CEO and thus are not reported in our disclosures.

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The tables below present information about revenues and other income, Segment Adjusted EBITDA, capital expenditures and investments in unconsolidated affiliates for our reportable segments:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
L&S
Service revenue	$	1,010	$	992	$	1,993	$	1,945
Rental income	208		176		383		425
Product related revenue	7		4		11		8
Sales-type lease revenue	114		136		225		173
Income from equity method investments	59		35		111		71
Other income	22		16		34		31
Total segment revenues and other income(1)	1,420		1,359		2,757		2,653
Segment Adjusted EBITDA(2)	966		947		1,870		1,843
Capital expenditures	81		76		158		135
Investments in unconsolidated affiliates	10		13		78		22
G&P
Service revenue	505		493		991		1,001
Rental income	92		91		173		183
Product related revenue	860		407		1,521		804
Income from equity method investments	52		31		99		65
Other income	11		14		9		28
Total segment revenues and other income(1)	1,520		1,036		2,793		2,081
Segment Adjusted EBITDA(2)	491		427		980		883
Capital expenditures	95		36		190		66
Investments in unconsolidated affiliates	$	36	$	36	$	78	$	62

(1)    Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $293 million for the three and six months ended June 30, 2022, respectively, and $138 million and $267 million for the three and six months ended June 30, 2021, respectively. Third party revenues for the G&P segment were $1,454 million and $2,666 million for the three and six months ended June 30, 2022, respectively, and $988 million and $1,977 million for the three and six months ended June 30, 2021, respectively.

(2)    See below for the reconciliation from Segment Adjusted EBITDA to Net income.

The table below provides a reconciliation between Net income and Segment Adjusted EBITDA.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Reconciliation to Net income:
L&S Segment Adjusted EBITDA	$	966	$	947	$	1,870	$	1,843
G&P Segment Adjusted EBITDA	491		427		980		883
Total reportable segments	1,457		1,374		2,850		2,726
Depreciation and amortization(1)	(310)		(318)		(623)		(647)
Impairment expense	—		(42)		—		(42)
Interest and other financial costs	(233)		(216)		(455)		(441)
Income from equity method investments	111		66		210		136
Distributions/adjustments related to equity method investments	(152)		(121)		(284)		(242)
Other	1		(38)		—		(47)
Adjusted EBITDA attributable to noncontrolling interests	10		10		19		20
Net income	$	884	$	715	$	1,717	$	1,463

(1)    Depreciation and amortization attributable to L&S was $129 million and $259 million for the three and six months ended June 30, 2022, respectively, and $136 million and $283 million for the three and six months ended June 30, 2021, respectively. Depreciation and

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amortization attributable to G&P was $181 million and $364 million for the three and six months ended June 30, 2022, respectively, and $182 million and $364 million for the three and six months ended June 30, 2021, respectively.

8. Property, Plant and Equipment

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

	June 30, 2022						December 31, 2021
(In millions)	Gross PP&E		Accumulated Depreciation		Net PP&E		Gross PP&E		Accumulated Depreciation(1)		Net PP&E
L&S	$	12,442	$	3,424	$	9,018	$	12,371	$	3,227	$	9,144
G&P	14,312		3,563		10,749		14,175		3,277		10,898
Total	$	26,754	$	6,987	$	19,767	$	26,546	$	6,504	$	20,042

(1)    Includes property, plant and equipment impairment charges recorded in the second quarter of 2021, 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.

In the second quarter of 2021, we recognized impairment expense of $42 million within our G&P segment related to our continued emphasis on portfolio optimization with the divestiture of several non-core assets and the closure of other non-core assets.

9. Fair Value Measurements

Fair Values – Recurring

Fair value measurements and disclosures relate primarily to MPLX’s derivative positions as discussed in Note 10.

Level 3 instruments relate to an embedded derivative liability for 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 $0.72 to $1.98 per gallon with a weighted average of $0.98 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal 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. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of June 30, 2022 or December 31, 2021.

Changes in Level 3 Fair Value Measurements

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

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Embedded derivatives in commodity contracts (net):
Fair value at beginning of period	$	(99)	$	(66)	$	(108)	$	(63)
Total gain/ (loss) (realized and unrealized) included in earnings(1)	4		(39)		8		(45)
Settlements	3		3		8		6
Fair value at end of period	(92)		(102)		(92)		(102)
The amount of total gain/ (loss) for the period included in earnings attributable to the change in unrealized gain/ (loss) relating to liabilities still held at end of period	$	3	$	(39)	$	8	$	(41)

(1)     Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs on the Consolidated Statements of Income.

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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 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 10).

The fair value of MPLX’s debt is estimated based on recent market non-binding indicative quotes. The debt fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs:

	June 30, 2022				December 31, 2021
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Outstanding debt(1)	$	18,604	$	19,881	$	20,779	$	18,664

(1)    Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

10. Derivative Financial Instruments

As of June 30, 2022, MPLX had no 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 2027. The customer has the unilateral option to extend the agreement for one five-year term through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending option have been aggregated into a single compound embedded derivative. The probability of the customer exercising its option 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. For further information regarding the fair value measurement of derivative instruments, see Note 9. As of June 30, 2022 and December 31, 2021, the estimated fair value of this contract was a liability of $92 million and $108 million, respectively.

Certain derivative positions are subject to master netting agreements, therefore, MPLX has elected to offset derivative assets and liabilities that are legally permissible to be offset. As of June 30, 2022 and December 31, 2021, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	June 30, 2022				December 31, 2021
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability		Asset		Liability
Commodity contracts
Other current assets / Other current liabilities	$	—	$	(14)	$	—	$	(15)
Other noncurrent assets / Other long-term liabilities	—		(78)		—		(93)
Total	$	—	$	(92)	$	—	$	(108)

We make a distinction between realized or 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. 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:

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	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Purchased product costs
Realized loss	$	(3)	$	(3)	$	(8)	$	(6)
Unrealized gain/ (loss)	7		(36)		16		(39)
Purchased product cost derivative gain/ (loss)	$	4	$	(39)	$	8	$	(45)

11. Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	June 30, 2022		December 31, 2021
MPLX LP:
MPLX Credit Agreement	$	—	$	300
Fixed rate senior notes	20,032		18,532
Consolidated subsidiaries:
MarkWest	23		23
ANDX	45		45
Financing lease obligations	8		9
Total	20,108		18,909
Unamortized debt issuance costs	(114)		(102)
Unamortized discount	(219)		(236)
Amounts due within one year	(1,000)		(499)
Total long-term debt due after one year	$	18,775	$	18,072

Credit Agreement

On July 7, 2022, MPLX entered into a new five-year credit agreement (the “New MPLX Credit Agreement”) to replace the previous $3.5 billion credit facility that was scheduled to expire July 2024. The New MPLX Credit Agreement, among other things, provides for a $2 billion unsecured revolving credit facility that matures in July 2027. The New MPLX Credit Agreement provides for letter of credit issuing capacity under the facility of $150 million. Letter of credit issuing capacity is included in, not in addition to, the $2 billion borrowing capacity of the New MPLX Credit Agreement. The financial covenants of the New MPLX Credit Agreement are substantially the same as those contained in the previous credit agreement. Borrowings under the New MPLX Credit Agreement bear interest, at MPLX’s election, at either the Adjusted Term SOFR or the Alternate Base Rate, both as defined in the New MPLX Credit Agreement, plus an applicable margin.

During the six months ended June 30, 2022, MPLX borrowed $900 million under the MPLX Credit Agreement, at an average interest rate of 1.454 percent, and repaid $1,200 million. At June 30, 2022, MPLX had no outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of approximately $3.5 billion.

Fixed Rate Senior Notes

MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes maturing between 2022 and 2058 with interest rates ranging from 1.750 percent to 5.500 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.

On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The 2052 Senior Notes were offered at a price to the public of 98.982 percent with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the intercompany loan agreement with MPC and the MPLX revolving credit facility.

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12. Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three and six months ended June 30, 2022 and 2021:

	Three Months Ended June 30, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	77	$	500	$	577
Service revenue - related parties	933		5		938
Service revenue - product related	—		118		118
Product sales	2		696		698
Product sales - related parties	5		46		51
Total revenues from contracts with customers	$	1,017	$	1,365	2,382
Non-ASC 606 revenue(1)					558
Total revenues and other income					$	2,940

	Three Months Ended June 30, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	91	$	487	$	578
Service revenue - related parties	901		6		907
Service revenue - product related	—		76		76
Product sales	1		303		304
Product sales - related parties	3		28		31
Total revenues from contracts with customers	$	996	$	900	1,896
Non-ASC 606 revenue(1)					499
Total revenues and other income					$	2,395

	Six Months Ended June 30, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	149	$	982	$	1,131
Service revenue - related parties	1,844		9		1,853
Service revenue - product related	—		241		241
Product sales	3		1,192		1,195
Product sales - related parties	8		88		96
Total revenues from contracts with customers	$	2,004	$	2,512	4,516
Non-ASC 606 revenue(1)					1,034
Total revenues and other income					$	5,550

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	Six Months Ended June 30, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	175	$	992	$	1,167
Service revenue - related parties	1,770		9		1,779
Service revenue - product related	—		153		153
Product sales	2		584		586
Product sales - related parties	6		67		73
Total revenues from contracts with customers	$	1,953	$	1,805	3,758
Non-ASC 606 revenue(1)					976
Total revenues and other income					$	4,734

(1)    Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

Contract Balances

Contract assets typically relate to deficiency payments related to minimum volume commitments and aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer. Contract assets are included in Other current assets and Other noncurrent 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. The sales and related Receivables, net 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 ASC 606 contract balances of each respective line, for the six-month periods ended June 30, 2022 and 2021:

(In millions)	Balance at December 31, 2021		Additions/ (Deletions)		Revenue Recognized(1)		Balance at June 30, 2022
Contract assets	$	25	$	(14)	$	—	$	11
Long-term contract assets	2		—		—		2
Deferred revenue	56		26		(25)		57
Deferred revenue - related parties	60		54		(57)		57
Long-term deferred revenue	135		17		—		152
Long-term deferred revenue - related parties	31		(3)		—		28
Long-term contract liabilities	$	5	$	—	$	—	$	5

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(In millions)	Balance at December 31, 2020		Additions/ (Deletions)		Revenue Recognized(1)		Balance at June 30, 2021
Contract assets	$	40	$	(25)	$	1	$	16
Long-term contract assets	2		—		—		2
Deferred revenue	37		24		(17)		44
Deferred revenue - related parties	91		37		(50)		78
Long-term deferred revenue	119		9		—		128
Long-term deferred revenue - related parties	48		(8)		—		40
Long-term contract liabilities	$	6	$	—	$	—	$	6

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

Remaining Performance Obligations

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

As of June 30, 2022, unsatisfied performance obligations included on the Consolidated Balance Sheets are $293 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 22 years. A portion of this amount is not disclosed in the table below as it is deemed variable consideration due to volume variability.

(In millions)
2022	$	943
2023	1,727
2024	1,601
2025	1,530
2026	1,373
2027 and thereafter	1,865
Total revenue on remaining performance obligations(1)(2)(3)	$	9,039

(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 and sales-type leases 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.

13. Supplemental Cash Flow Information

	Six Months Ended June 30,
(In millions)	2022		2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	393	$	414
Income taxes paid	$	1	$	1

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

	Six Months Ended June 30,
(In millions)	2022		2021
Increase/ (decrease) in capital accruals	$	54	$	(34)

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14. Leases

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

	Three Months Ended  June 30, 2022				Three Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	198	$	102	$	168	$	99
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	112		—		135		—
Interest income (Revenue from variable lease payments)	2		—		1		—
Sales-type lease revenue	$	114	$	—	$	136	$	—

	Six Months Ended  June 30, 2022				Six Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	363	$	193	$	410	$	198
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	222		—		172		—
Interest income (Revenue from variable lease payments)	3		—		1		—
Sales-type lease revenue	$	225	$	—	$	173	$	—

See Note 4 for additional information on where related party lease assets are recorded in the Consolidated Balance Sheets. Capital expenditures related to assets subject to sales-type lease arrangements were $18 million for the six months ended June 30, 2022, these amounts are reflected as Additions to property, plant and equipment on the Consolidated Statements of Cash Flows. As of June 30, 2022 and December 31, 2021, third party lease assets are less than $1 million and are included within the Receivables, net and Other noncurrent assets captions within the Consolidated Balance Sheets.

During the second quarter of 2021, reimbursements for projects and changes to minimum volume commitments at certain L&S locations were agreed to between MPLX and MPC. These reimbursements and minimum volume commitments relate to the storage, transportation and terminal services agreements between MPLX and MPC at these locations and required the embedded leases within these agreements to be reassessed under ASC 842. As a result of the reassessment, certain leases were reclassified from an operating lease to a sales-type lease. Accordingly, the underlying assets previously shown on the Consolidated Balance Sheets associated with the sales-type leases 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 during the respective periods. See Note 4 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 the impacted storage and terminal services agreements are related to a common control transaction. During the second quarter of 2021, MPLX derecognized approximately $421 million of property, plant and equipment, recorded a lease receivable of approximately $519 million, recorded an unguaranteed residual asset of approximately $14 million with the difference recorded as a deemed Contribution from MPC of $112 million.

15. 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 a liability, MPLX is unable to estimate a range of possible loss 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.

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Environmental Matters

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

At June 30, 2022 and December 31, 2021, accrued liabilities for remediation totaled $27 million and $23 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, that may be imposed.

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.

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.

We hold a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. Completion of the EIS may now be delayed as the Army Corps engages with the Standing Rock Sioux Tribe on the tribe’s reasons for withdrawing as a cooperating agency with respect to preparation of the EIS.

In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.

We have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, has 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. If the pipeline were temporarily shut down, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of June 30, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.

Other Legal Proceedings

In July 2020, Tesoro High Plains Pipeline Company, LLC (“THPP”), a subsidiary of MPLX, received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification demanded the immediate cessation of pipeline operations and assessed trespass damages of approximately $187 million. On appeal, the Assistant Secretary - Indian Affairs issued an order vacating the BIA’s trespass order and remanded to the Regional Director for the BIA Great Plains Region to issue a new decision based on specific criteria. On December 15, 2020, the Regional Director of the BIA issued a new trespass notice to THPP, finding that THPP was in trespass and assessing trespass damages of approximately $4 million (including interest), which has been paid. The order also required that THPP immediately cease and desist use of the portion of the pipeline that crosses the property at issue. THPP has complied with the Regional Director’s December 15, 2020 notice. In March 2021, THPP received a copy of an order purporting to vacate all orders related to THPP’s alleged trespass issued by the BIA between July 2, 2020 and January 14, 2021. The order directs the Regional Director of the BIA to reconsider the issue of THPP’s alleged trespass and issue a new

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order, if necessary, after all interested parties have had an opportunity to be heard. Subsequently, landowners voluntarily dismissed the suit filed in the District of North Dakota. On April 23, 2021, THPP filed a lawsuit in the District of North Dakota against the United States of America, the U.S. Department of the Interior and the BIA (together, the “U.S. Government Parties”) challenging the March order purporting to vacate all previous orders related to THPP’s alleged trespass.

On February 8, 2022, the U.S. Government Parties filed their answer to THPP’s suit, asserting counterclaims for trespass and ejectment. The U.S. Government Parties claim THPP is in continued trespass with respect to the pipeline and seek disgorgement of pipeline profits from June 1, 2013 to present, removal of the pipeline and remediation. We intend to vigorously defend ourselves against these counterclaims. We continue to work towards a settlement of this matter with holders of the property rights at issue.

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 other lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated financial position, results of operations or cash flows.

Contractual Commitments and Contingencies

From time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of June 30, 2022, 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.

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, 2021.

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,” “intend,” “may,” “objective,” “opportunity,” “outlook,” “plan,” “policy,” “position,” “potential,” “predict,” “priority,” “project,” “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 financial and operating results;

•environmental, social and governance (“ESG”) goals and targets, including those related to greenhouse gas emissions, diversity and inclusion and ESG reporting;

•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;

•business strategies, growth opportunities and expected investments;

•the timing and amount of future distributions or unit repurchases; and

•the anticipated effects of actions of third parties such as competitors, activist investors, 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. 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 continuance or escalation of the military conflict between Russia and Ukraine, and related sanctions and market disruptions;

•general economic, political or regulatory developments, including inflation, changes in governmental policies relating to refined petroleum products, crude oil, natural gas or NGLs, or taxation;

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•the magnitude, duration and extent of future resurgences of the COVID-19 pandemic and its restrictions, including travel restrictions, business and school closures, increased remote work, stay-at-home orders and other actions taken by individuals, governments and the private sector to stem the spread of the virus;

•the ability of MPC to achieve its strategic objectives and the effects of those strategic decisions on us;

•changes in estimates or projections used to assess fair value of intangible assets, goodwill and property and equipment and/or strategic decisions or other developments with respect to our assets that cause impairment charges;

•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 our business, financial condition, results of operations and cash flows;

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

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

•volatility in or degradation of market and industry conditions;

•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 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;

•changes in 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;

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

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

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

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

•midstream and refining industry overcapacity or under capacity;

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

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

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

For additional risk factors affecting our business, see the risk factors described in our Annual Report on Form 10-K for the year ended December 31, 2021. We undertake no obligation to update any forward-looking statement 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. The business consists of two segments based on the nature of services it offers:

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Logistics and Storage (“L&S”), and Gathering and Processing (“G&P”). The L&S segment is engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products. The L&S segment also includes the operation of our refining logistics, fuels distribution and inland marine businesses, terminals, rail facilities and storage caverns. The G&P segment provides gathering, processing and transportation of natural gas; and the transportation, fractionation, storage and marketing of NGLs.

Significant Financial and Other Highlights

Significant financial highlights including revenues and other income, income from operations, net income, adjusted EBITDA attributable to MPLX and DCF attributable to GP and LP unitholders for the three months ended June 30, 2022 and June 30, 2021 are shown in the chart below. 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.

Other Highlights

•Generated net cash provided by operating activities of $1,487 million and free cash flow after distributions of $614 million in the second quarter of 2022.

•Announced a second quarter 2022 distribution of $0.7050 per common unit, resulting in a distribution coverage ratio of 1.69x for the second quarter.

•Returned $35 million and $135 million of cash to unitholders in the three and six months ended June 30, 2022, respectively, through the repurchase of common units under our unit repurchase program. We repurchased 1,037,434 and 4,156,956 common units during the three and six months ended June 30, 2022, respectively. As of June 30, 2022, we had $202 million remaining under the existing unit repurchase authorization.

•On August 2, 2022, MPLX announced the board of directors approved an incremental $1 billion unit repurchase authorization. The authorization has no expiration date.

•Renewed transportation service contracts with MPC, which were set to expire in 2022, extending the term by 10 years.

Current Economic Environment

Through the first six months of 2022, we continue to see recovery in the environment in which our business operates. The increase in global demand for refined products and global commodity supply constraints have contributed to improved throughputs and higher natural gas and NGL prices. We are unable to predict the potential effects that resurgences of COVID-19 or the continuance or escalation of the military conflict between Russia and Ukraine, and related sanctions, may have on our financial position and results. It remains uncertain how long these conditions may last or how severe they may become.

In 2022, data indicates a sharp rise in inflation in the U.S. and globally. Current and future inflationary effects may be driven by, among other things, supply chain disruptions, governmental stimulus or fiscal policies and increasing demand for certain goods and services as recovery from the COVID-19 pandemic continues. We have observed higher costs for labor and materials used in our business. We cannot predict the effect of higher inflation and fuel prices on demand for our products and services. In response to this business environment, MPLX remains focused on executing its strategic priorities of strict capital discipline, embedding a low-cost culture, and portfolio optimization.

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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, DCF, free cash flow (“FCF”) and free cash flow after distributions. 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. Management also utilizes Segment Adjusted EBITDA in evaluating the financial performance of our segments. The use of this measure allows investors to understand how management evaluates financial performance to make operating decisions and allocate resources.

We define Adjusted EBITDA as net income adjusted for: (i) depreciation and amortization; (ii) provision/(benefit) for income taxes; (iii) interest and other financial costs; (iv) impairment expense; (v) income from equity method investments; (vi) distributions and adjustments related to equity method investments; (vii) noncontrolling interests; and (viii) other adjustments as deemed necessary. We also use DCF, which we define as Adjusted EBITDA adjusted for: (i) deferred revenue impacts; (ii) sales-type lease payments, net of income; (iii) net interest and other financial costs; (iv) net maintenance capital expenditures; (v) equity method investment capital expenditures paid out; and (vi) other adjustments as deemed necessary. Segment Adjusted EBITDA represents Adjusted EBITDA attributable to the reportable segments.

We define FCF as net cash provided by operating activities adjusted for (i) net cash used in investing activities; (ii) cash contributions from MPC; (iii) cash contributions from noncontrolling interests and (iv) cash distributions to noncontrolling interests. We define free cash flow after distributions as FCF less base distributions to common and preferred unitholders.

We believe that the presentation of Adjusted EBITDA, DCF, FCF and free cash flow after distributions 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 while the GAAP measure most directly comparable to FCF and free cash flow after distributions is net cash provided by operating activities. These non-GAAP financial measures should not be considered alternatives to GAAP net income or net cash provided by operating activities as they 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. These non-GAAP financial measures should not be considered in isolation or as substitutes for analysis of our results as reported under GAAP. Additionally, because non-GAAP financial measures may be defined differently by other companies in our industry, our definitions 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 the Results of Operations section. For a reconciliation of FCF and free cash flow after distributions to their most directly comparable measure calculated and presented in accordance with GAAP, see the Liquidity and Capital resources section.

Comparability of our Financial Results

During the normal course of business, we amend or modify our contractual agreements with customers. These amendments or modifications require the agreements to be reassessed under ASC 842, which can impact the classification of revenues or costs associated with the agreement. These reassessments may impact the comparability of our financial results.

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Results of Operations

The following tables and discussion are a summary of our results of operations for the three and six months ended June 30, 2022 and 2021, including a reconciliation of Adjusted EBITDA and DCF from Net income and Net cash provided by operating activities, to the most directly comparable GAAP financial measures.

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2022		2021		Variance		2022		2021		Variance
Revenues and other income:
Total revenues and other income	$	2,940	$	2,395	$	545	$	5,550	$	4,734	$	816
Costs and expenses:
Cost of revenues (excludes items below)	323		293		30		610		566		44
Purchased product costs	663		338		325		1,130		614		516
Rental cost of sales	42		32		10		79		64		15
Rental cost of sales - related parties	19		23		(4)		34		62		(28)
Purchases - related parties	351		297		54		670		595		75
Depreciation and amortization	310		318		(8)		623		647		(24)
Impairment expense	—		42		(42)		—		42		(42)
General and administrative expenses	82		87		(5)		160		173		(13)
Other taxes	33		34		(1)		67		66		1
Total costs and expenses	1,823		1,464		359		3,373		2,829		544
Income from operations	1,117		931		186		2,177		1,905		272
Related party interest and other financial costs	1		2		(1)		5		2		3
Interest expense, net of amounts capitalized	212		195		17		410		393		17
Other financial costs	20		19		1		40		46		(6)
Income before income taxes	884		715		169		1,722		1,464		258
Provision for income taxes	—		—		—		5		1		4
Net income	884		715		169		1,717		1,463		254
Less: Net income attributable to noncontrolling interests	9		9		—		17		18		(1)
Net income attributable to MPLX LP	875		706		169		1,700		1,445		255
Adjusted EBITDA attributable to MPLX LP(1)	1,457		1,374		83		2,850		2,726		124
DCF attributable to GP and LP unitholders(1)	$	1,206	$	1,219	$	(13)	$	2,384	$	2,325	$	59

(1)    Non-GAAP measure. See reconciliation below to the most directly comparable GAAP measures.

30

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2022		2021		Variance		2022		2021		Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income:
Net income	$	884	$	715	$	169	$	1,717	$	1,463	$	254
Provision for income taxes	—		—		—		5		1		4
Interest and other financial costs	233		216		17		455		441		14
Income from operations	1,117		931		186		2,177		1,905		272
Depreciation and amortization	310		318		(8)		623		647		(24)
Impairment expense	—		42		(42)		—		42		(42)
Income from equity method investments	(111)		(66)		(45)		(210)		(136)		(74)
Distributions/adjustments related to equity method investments	152		121		31		284		242		42
Other	(1)		38		(39)		(5)		46		(51)
Adjusted EBITDA	1,467		1,384		83		2,869		2,746		123
Adjusted EBITDA attributable to noncontrolling interests	(10)		(10)		—		(19)		(20)		1
Adjusted EBITDA attributable to MPLX LP	1,457		1,374		83		2,850		2,726		124
Deferred revenue impacts	24		40		(16)		48		62		(14)
Sales-type lease payments, net of income	5		54		(49)		10		54		(44)
Net interest and other financial costs(1)	(215)		(198)		(17)		(419)		(418)		(1)
Maintenance capital expenditures, net of reimbursements	(39)		(18)		(21)		(53)		(29)		(24)
Equity method investment capital expenditures paid out	(3)		(2)		(1)		(6)		(3)		(3)
Other	8		—		8		17		(5)		22
DCF	1,237		1,250		(13)		2,447		2,387		60
Preferred unit distributions	(31)		(31)		—		(63)		(62)		(1)
DCF attributable to GP and LP unitholders	$	1,206	$	1,219	$	(13)	$	2,384	$	2,325	$	59

(1)    Excludes gain/ loss on extinguishment of debt and amortization of deferred financing costs.

31

	Six Months Ended June 30,
(In millions)	2022		2021		Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net cash provided by operating activities:
Net cash provided by operating activities	$	2,612	$	2,489	$	123
Changes in working capital items	(148)		(131)		(17)
All other, net	(36)		(29)		(7)
Gain on extinguishment of debt	—		(12)		12
Net interest and other financial costs(1)	419		418		1
Other adjustments to equity method investment distributions	26		3		23
Other	(4)		8		(12)
Adjusted EBITDA	2,869		2,746		123
Adjusted EBITDA attributable to noncontrolling interests	(19)		(20)		1
Adjusted EBITDA attributable to MPLX LP	2,850		2,726		124
Deferred revenue impacts	48		62		(14)
Sales-type lease payments, net of income(2)	10		54		(44)
Net interest and other financial costs(1)	(419)		(418)		(1)
Maintenance capital expenditures, net of reimbursements	(53)		(29)		(24)
Equity method investment capital expenditures paid out	(6)		(3)		(3)
Other	17		(5)		22
DCF	2,447		2,387		60
Preferred unit distributions	(63)		(62)		(1)
DCF attributable to GP and LP unitholders	$	2,384	$	2,325	$	59

(1)    Excludes gain/loss on extinguishment of debt and amortization of deferred financing costs.

(2)    The six months ended June 30, 2021 includes one-time impact from Refining Logistics harmonization project of $54 million.

Three months ended June 30, 2022 compared to three months ended June 30, 2021

Total revenues and other income increased $545 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher prices and volumes in most regions in the G&P segment of approximately $466 million. There were also increased revenue from terminal activities and fee escalations, as well as higher income from equity method investments.

Cost of revenues increased $30 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher spending driven by the timing of expense projects and higher operating costs.

Purchased product costs increased $325 million in the second quarter of 2022 compared to the same period of 2021 This was primarily due to higher prices of $287 million in the Southwest and Southern Appalachia and higher volumes in the Southwest, partially offset by a decrease of $43 million due to changes in the fair value of our embedded derivative.

Rental cost of sales and rental cost of sales - related parties increased $6 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher operating costs and repairs and maintenance costs in the Marcellus and to modifications to lease contracts which resulted in a greater portion of costs being recorded to purchases - related parties, as noted below.

Purchases - related parties increased $54 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in a greater portion of costs now being recorded to purchases - related parties as opposed to rental cost of sales - related parties costs, as noted above, as well as to increased transportation, employee, and project-related costs.

32

Six months ended June 30, 2022 compared to six months ended June 30, 2021

Total revenues and other income increased $816 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to higher prices and volumes in most regions in the G&P segment of approximately $697 million. There were also increased pipeline fees in the L&S segment due to higher pipeline throughput outweighing decreased average tariff rates, increased revenue from terminal activities, increased revenue from the recognition of volume deficiency credits, as well as a $74 million increase in income from equity method investments. These increases were partially offset by a loss on disposal of assets.

Cost of revenues increased $44 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to increased operating costs driven by the timing of expense projects and higher environmental response and remediation costs. Additionally, higher repairs and maintenance costs in the Marcellus and Rockies were partially offset by lower costs in the Southwest.

Purchased product costs increased $516 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to higher prices of $430 million in the Southwest and Southern Appalachia and higher volumes in the Southwest, partially offset by a decrease of $55 million due to changes in the fair value of our embedded derivative.

Rental cost of sales and rental cost of sales - related parties decreased $13 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs now being recorded to purchases - related parties, as noted below, as opposed to rental cost of sales - related parties. The decreases were partially offset by increased miscellaneous expenses as well as higher operating costs and repairs and maintenance costs in the Marcellus.

Purchases - related parties increased $75 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs now being recorded to purchases - related parties as opposed to rental cost of sales - related parties, as noted above. There were also increased transportation costs and other miscellaneous increases. These increases were partially offset by decreased employee-related costs from MPC.

Depreciation and amortization decreased $24 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to the prior year derecognition of fixed assets resulting from the modification of certain lease contracts and accelerated depreciation on refining logistics assets at MPC’s idled Gallup refinery.

33

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) interest and other financial costs; (iii) impairment expense; (iv) income/(loss) from equity method investments; (v) distributions and adjustments related to equity method investments; (vi) noncontrolling interests; and (vii) other adjustments as deemed necessary. These items are either: (i) believed to be non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about Segment Adjusted EBITDA for the reported segments for the three and six months ended June 30, 2022 and 2021.

L&S Segment

Second Quarter L&S Segment Financial Highlights (in millions)

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2022		2021		Variance		2022		2021		Variance
Service revenue	$	1,010	$	992	$	18	$	1,993	$	1,945	$	48
Rental income	208		176		32		383		425		(42)
Product related revenue	7		4		3		11		8		3
Sales-type lease revenue	114		136		(22)		225		173		52
Income from equity method investments	59		35		24		111		71		40
Other income	22		16		6		34		31		3
Total segment revenues and other income	1,420		1,359		61		2,757		2,653		104
Cost of revenues	159		143		16		300		287		13
Purchases - related parties	258		228		30		497		443		54
Depreciation and amortization	129		136		(7)		259		283		(24)
General and administrative expenses	43		46		(3)		86		92		(6)
Other taxes	20		19		1		41		38		3
Segment income from operations	811		787		24		1,574		1,510		64
Depreciation and amortization	129		136		(7)		259		283		(24)
Income from equity method investments	(59)		(35)		(24)		(111)		(71)		(40)
Distributions/adjustments related to equity method investments	79		58		21		137		116		21
Other	6		1		5		11		5		6
Segment adjusted EBITDA(1)	966		947		19		1,870		1,843		27
Capital expenditures	81		76		5		158		135		23
Investments in unconsolidated affiliates(2)	$	10	$	13	$	(3)	$	78	$	22	$	56

(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.

(2)    The six months ended June 30, 2022 includes a contribution of $60 million to our Bakken Pipeline joint venture to fund our share of a debt repayment by the joint venture.

34

Three months ended June 30, 2022 compared to three months ended June 30, 2021

Service revenue increased $18 million in the second quarter of 2022 compared to the same period of 2021. This was primarily driven by higher revenue recognized from increased revenue from terminal activities and annual fee escalations. These increases were partially offset by a net decrease in pipeline transportation fees due to lower tariff rates outweighing higher throughput volumes as well as a net decrease of $15 million from changes in the presentation of revenue between service revenue, rental income and sales-type lease revenue driven by modifications to agreements with MPC.

Rental income increased $32 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to a net increase of $36 million from changes in the presentation of revenue between service revenue, rental income and sales-type lease revenue driven by modifications to agreements with MPC. Annual fee escalations also contributed to the increase.

Sales-type lease revenue - related parties decreased $22 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to a decrease of $21 million from changes in the presentation of revenue between service revenue, rental income and sales-type lease revenue as a result of modifications to agreements with MPC.

Income from equity methods investments increased $24 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to increased throughput on equity method investment pipeline systems, including the Whistler pipeline which was placed into service in the third quarter of 2021.

Cost of revenues increased $16 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher project-related costs. The increases were partially offset by modifications to lease contracts which resulted in a greater portion of costs being recorded to purchases - related parties, as noted below.

Purchases - related parties increased $30 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in a greater portion of costs now being recorded to purchases - related parties as opposed to rental cost of sales - related parties, which is included in cost of revenues as noted above, as well as to increased project-related costs.

Six months ended June 30, 2022 compared to six months ended June 30, 2021

Service revenue increased $48 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to increased revenue from terminal activities, annual fee escalations, and higher revenue recognized from volume deficiency credits. Additionally, there was a net increase in pipeline fees due to increased throughput outweighing lower average tariff rates.

Rental income decreased $42 million in the first six months of 2022 compared to the same period of 2021. This was due to a net decrease of $52 million from changes in the presentation of lease income between service revenue, rental income and sales-type lease revenue as a result of modifications to lease contracts. The decrease was partially offset by increased storage fees and fee escalations.

Sales-type lease revenue - related parties increased $52 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to an increase of $52 million from changes in the presentation of lease income between service revenue, rental income and sales-type lease revenue driven by modifications of lease contracts.

Income from equity methods investments increased $40 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to increased throughput on equity method investment pipeline systems, including the Whistler pipeline which was placed into service in the third quarter of 2021.

Cost of revenues increased $13 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to higher project-related costs and higher environmental response and remediation costs compared to the first half of 2021. The increases were partially offset by modifications to lease contracts which resulted in costs being recorded to purchases - related parties, as noted below.

Purchases - related parties increased $54 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs now being recorded to purchases - related parties as opposed to rental cost of sales - related parties, which is included in cost of revenues as noted above. This increase as well as increased project-related costs, were partially offset by decreased employee-related costs from MPC.

Depreciation and amortization decreased $24 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to the derecognition of fixed assets due to the modification of certain lease contracts and accelerated depreciation on refining logistics assets at MPC’s idled Gallup refinery.

35

L&S Operating Data

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
L&S
Pipeline throughput (mbpd)
Crude oil pipelines	3,674		3,475		3,527		3,379
Product pipelines	2,247		2,103		2,103		1,981
Total pipelines	5,921		5,578		5,630		5,360
Average tariff rates ($ per barrel)(1)
Crude oil pipelines	$	0.86	$	0.95	$	0.89	$	0.95
Product pipelines	0.77		0.77		0.80		0.78
Total pipelines	$	0.82	$	0.88	$	0.85	$	0.89
Terminal throughput (mbpd)	3,101		2,986		3,021		2,801
Marine Assets (number in operation)(2)
Barges	296		299		296		299
Towboats	23		23		23		23

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

(2)     Represents total at end of period.

36

G&P Segment

Second Quarter G&P Segment Financial Highlights (in millions)

	Three Months Ended June 30,						Six Months Ended June 30,
(In millions)	2022		2021		Variance		2022		2021		Variance
Service revenue	$	505	$	493	$	12	$	991	$	1,001	$	(10)
Rental income	92		91		1		173		183		(10)
Product related revenue	860		407		453		1,521		804		717
Income from equity method investments	52		31		21		99		65		34
Other income	11		14		(3)		9		28		(19)
Total segment revenues and other income	1,520		1,036		484		2,793		2,081		712
Cost of revenues	225		205		20		423		405		18
Purchased product costs	663		338		325		1,130		614		516
Purchases - related parties	93		69		24		173		152		21
Depreciation and amortization	181		182		(1)		364		364		—
Impairment expense	—		42		(42)		—		42		(42)
General and administrative expenses	39		41		(2)		74		81		(7)
Other taxes	13		15		(2)		26		28		(2)
Segment income from operations	306		144		162		603		395		208
Depreciation and amortization	181		182		(1)		364		364		—
Impairment expense	—		42		(42)		—		42		(42)
Income from equity method investments	(52)		(31)		(21)		(99)		(65)		(34)
Distributions/adjustments related to equity method investments	73		63		10		147		126		21
Other	(7)		37		(44)		(16)		41		(57)
Adjusted EBITDA attributable to noncontrolling interests	(10)		(10)		—		(19)		(20)		1
Segment Adjusted EBITDA(1)	491		427		64		980		883		97
Capital expenditures	95		36		59		190		66		124
Investments in unconsolidated affiliates	$	36	$	36	$	—	$	78	$	62	$	16

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

Three months ended June 30, 2022 compared to three months ended June 30, 2021

Service revenue increased $12 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher fees from higher volumes in the Southwest, an increase due to a 2021 contract modification in the Marcellus resulting in a change in the presentation of the related income from rental income to service revenue.

37

Product related revenue increased $453 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher prices in the Southwest, Marcellus, Southern Appalachia and Bakken of approximately $333 million and higher volumes in the Southwest, Rockies, Bakken and Marcellus of $121 million.

Income from equity method investments increased $21 million in the second quarter of 2022 compared to the same period of 2021, primarily due to an impairment recorded in the second quarter of 2021 and higher volumes associated with joint ventures in the Southwest and Utica regions.

Cost of revenues increased $20 million in the second quarter of 2022 compared to the same period of 2021. This increase is attributable to higher operating costs and repairs and maintenance costs in the Marcellus and Rockies.

Purchased product costs increased $325 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to higher prices of $287 million in the Southwest and Southern Appalachia and higher volumes in the Southwest, partially offset by a decrease of $43 million due to changes in the fair value of our embedded derivative.

Purchases - related parties increased $24 million in the second quarter of 2022 compared to the same period of 2021. This was primarily due to an increase in transportation costs to related parties and an increase in employee related costs with related parties.

Impairment expense decreased $42 million in the second quarter of 2022 compared to the same period of 2021 due to impairments recorded in the second quarter of 2021.

Six months ended June 30, 2022 compared to six months ended June 30, 2021

Service revenue decreased $10 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to a decrease in revenue related to cost reimbursements in the Rockies, and lower fees from lower volumes in the Marcellus, partially offset by an increase due to a 2021 contract modification in the Marcellus resulting in a change in the presentation of the related income from rental income to service revenue, and higher fees from higher volumes in the Southwest.

Rental income decreased $10 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to a 2021 contract modification in the Marcellus resulting in a change in the presentation of the related income from rental income to service revenue, partially offset by an increase in cost reimbursement revenue in the Marcellus and Southern Appalachia.

Product related revenue increased $717 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to higher prices in the Southwest, Marcellus, Southern Appalachia and Bakken of approximately $520 million and higher fees from higher volumes in the Southwest, Rockies, Bakken and Marcellus of $208 million.

Income from equity method investments increased $34 million in the first six months of 2022 compared to the same period of 2021, primarily due to higher volumes and rates associated with joint ventures in the Utica, Marcellus and Southwest regions and an impairment recorded in the second quarter of 2021.

Other income decreased $19 million in the first six months of 2022 compared to the same period of 2021 due to a loss on disposal of assets.

Cost of revenues increased $18 million in the first six months of 2022 compared to the same period of 2021. This increase is attributable to higher operating costs and repairs and maintenance costs in the Marcellus and Rockies, partially offset by lower costs in the Southwest.

Purchased product costs increased $516 million in the first six months of 2022 compared to the same period of 2021. This was primarily due to higher prices of $430 million in the Southwest and Southern Appalachia and higher volumes in the Southwest, partially offset by a decrease of $55 million due to changes in the fair value of our embedded derivative.

Purchases - related parties increased $21 million in the first six months of 2022 compared to the same period of 2021, this was primarily due to an increase in transportation costs to related parties and an increase in employee related costs with related parties.

Impairment expense decreased $42 million in the first six months of 2022 compared to the same period of 2021 due to impairments recorded in the second quarter of 2021.

38

G&P Operating Data

	Three Months Ended  June 30, 2022		Three Months Ended  June 30, 2021
	MPLX LP(1)	MPLX LP Operated(2)	MPLX LP(1)	MPLX LP Operated(2)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,287	1,287	1,300	1,300
Utica Operations	—	1,943	—	1,531
Southwest Operations	1,429	1,694	1,356	1,496
Bakken Operations	148	148	155	155
Rockies Operations	425	554	442	595
Total gathering throughput	3,289	5,626	3,253	5,077
Natural Gas Processed (MMcf/d)
Marcellus Operations	3,987	5,445	4,155	5,605
Utica Operations	—	522	—	499
Southwest Operations	1,401	1,696	1,326	1,461
Southern Appalachian Operations	231	231	224	224
Bakken Operations	142	142	154	154
Rockies Operations	440	440	429	429
Total natural gas processed	6,201	8,476	6,288	8,372
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(3)	471	471	477	477
Utica Operations(3)	—	30	—	27
Southwest Operations	—	—	—	—
Southern Appalachian Operations	12	12	12	12
Bakken Operations	20	20	25	25
Rockies Operations	3	3	4	4
Total C2 + NGLs fractionated(4)	506	536	518	545

39

	Six Months Ended  June 30, 2022		Six Months Ended  June 30, 2021
	MPLX LP(1)	MPLX LP Operated(2)	MPLX LP(1)	MPLX LP Operated(2)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,300	1,300	1,299	1,299
Utica Operations	—	1,879	—	1,549
Southwest Operations	1,369	1,586	1,364	1,472
Bakken Operations	147	147	150	150
Rockies Operations	410	540	457	611
Total gathering throughput	3,226	5,452	3,270	5,081
Natural Gas Processed (MMcf/d)
Marcellus Operations	4,001	5,487	4,201	5,641
Utica Operations	—	473	—	506
Southwest Operations(5)	1,392	1,618	1,311	1,414
Southern Appalachian Operations	228	228	226	226
Bakken Operations	143	143	149	149
Rockies Operations	423	423	435	435
Total natural gas processed	6,187	8,372	6,322	8,371
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(3)	469	469	483	483
Utica Operations(3)	—	27	—	28
Southwest Operations(5)	—	—	4	4
Southern Appalachian Operations	11	11	11	11
Bakken Operations	20	20	22	22
Rockies Operations	4	4	4	4
Total C2 + NGLs fractionated(4)	504	531	524	552

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Pricing Information
Natural Gas NYMEX HH ($ per MMBtu)	$	7.50	$	2.97	$	6.04	$	2.85
C2 + NGL Pricing ($ per gallon)(6)	$	1.18	$	0.75	$	1.16	$	0.74

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

(2)     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.

(3)     Entities within the Marcellus and Utica Operations jointly own the Hopedale fractionation complex. Hopedale throughput is included in the Marcellus and Utica Operations and represent each region’s utilization of the complex.

(4)     Purity ethane makes up approximately 194 mbpd and 190 mbpd of total MPLX Operated, fractionated products for the three months ended June 30, 2022 and 2021, respectively, and approximately 191 mbpd and 195 mbpd of total fractionated products for the six months ended June 30, 2022 and 2021, respectively. Purity ethane makes up approximately 189 mbpd and 185 mbpd of total MPLX LP consolidated, fractionated products for the three months ended June 30, 2022 and 2021, respectively, and approximately 187 mbpd and 190 mbpd of total fractionated products for the six months ended June 30, 2022 and 2021, respectively.

(5)    The Southwest Operations for the six months ended June 30, 2021 include the Javelina complex, which was sold on February 12, 2021. The processing and fractionated volumes calculated for the number of days MPLX owned these assets during 2021 were 96 MMcf/d and 17 mbpd, respectively.

(6)    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.

40

Seasonality

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

In our G&P segment, we experience minimal impacts from seasonal fluctuations which impact the demand for natural gas and NGLs and the related 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.

Liquidity and Capital Resources

Cash Flows

Our cash and cash equivalents were $298 million at June 30, 2022 and $13 million at December 31, 2021. The change in cash, cash equivalents and restricted cash was due to the factors discussed below. Net cash provided by (used in) operating activities, investing activities and financing activities were as follows:

	Six Months Ended June 30,
(In millions)	2022		2021
Net cash provided by (used in):
Operating activities	$	2,612	$	2,489
Investing activities	(411)		(245)
Financing activities	(1,916)		(2,251)
Total	$	285	$	(7)

Net cash provided by operating activities increased $123 million in the first six months of 2022 compared to the first six months of 2021, primarily due to increased net income, higher distributions from equity methods investments and decreased working capital requirements offset by higher income from equity method investments.

Net cash used in investing activities increased $166 million in the first six months of 2022 compared to the first six months of 2021, primarily due to higher capital spending and an increase in contributions to equity method investments, which included the $60 million contribution to our Bakken Pipeline joint venture to fund our share of a debt repayment by the joint venture.

Financing activities were an $1,916 million use of cash in the first six months of 2022 compared to a $2,251 million use of cash in the first six months of 2021. The primary reason for the decrease in the use of cash was due to net debt repayments of $266 million in the first half of 2022 compared to net debt repayments of $453 million in the first half of 2021 as well as $175 million in lower unit repurchases in the first half of 2022 compared to the first half of 2021.

Free Cash Flow

The following table provides a reconciliation of FCF and free cash flow after distributions from net cash provided by operating activities for the three and six months ended June 30, 2022 and June 30, 2021.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Net cash provided by operating activities	$	1,487	$	1,365	$	2,612	$	2,489
Adjustments to reconcile net cash provided by operating activities to free cash flow
Net cash used in investing activities	(135)		(155)		(411)		(245)
Contributions from MPC	7		10		17		17
Distributions to noncontrolling interests	(10)		(10)		(19)		(20)
Free cash flow	1,349		1,210		2,199		2,241
Distributions paid to common and preferred unitholders	(735)		(729)		(1,493)		(1,483)
Free cash flow after distributions	$	614	$	481	$	706	$	758

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Debt and Liquidity Overview

On July 7, 2022, MPLX entered into a new five-year credit agreement (the “New MPLX Credit Agreement”) to replace the previous $3.5 billion credit facility that was scheduled to expire July 2024. The New MPLX Credit Agreement, among other things, provides for a $2 billion unsecured revolving credit facility that matures in July 2027. The New MPLX Credit Agreement provides for letter of credit issuing capacity under the facility of $150 million. Letter of credit issuing capacity is included in, not in addition to, the $2 billion borrowing capacity of the New MPLX Credit Agreement. The financial covenants of the New MPLX Credit Agreement are substantially the same as those contained in the previous credit agreement. Borrowings under the New MPLX Credit Agreement bear interest, at MPLX’s election, at either the Adjusted Term SOFR or the Alternate Base Rate, both as defined in the New MPLX Credit Agreement, plus an applicable margin.

On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The 2052 Senior Notes were offered at a price to the public of 98.982 percent with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the intercompany loan agreement with MPC and the MPLX revolving credit facility.

As of June 30, 2022, we had $20.1 billion in aggregate principal amount of senior notes outstanding. The increase compared to year-end 2021 resulted from the issuance of the 2052 Senior Notes, as discussed above.

Our intention is to maintain an investment-grade credit profile. As of June 30, 2022, the credit ratings on our senior unsecured debt were at or above investment grade level as follows:

Rating Agency	Rating
Moody’s	Baa2 (stable outlook)
Standard & Poor’s	BBB (stable outlook)
Fitch	BBB (stable 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 New MPLX Credit Agreement contains 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 New MPLX Credit Agreement) for the prior four fiscal quarters of no greater than 5.0 to 1.0 (or 5.5 to 1.0 during the six-month period following certain acquisitions). Consolidated EBITDA is subject to adjustments for certain acquisitions completed and capital projects undertaken during the relevant period. Other covenants restrict us and/or certain of our subsidiaries from incurring debt, creating liens on assets and entering into transactions with affiliates. As of June 30, 2022, we were in compliance with the covenants, including the financial covenant with a ratio of Consolidated Total Debt to Consolidated EBITDA of 3.54 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 New MPLX Credit Agreement and may limit our ability to obtain future financing, including refinancing existing indebtedness.

Our liquidity totaled $5.3 billion at June 30, 2022 consisting of:

	June 30, 2022
(In millions)	Total Capacity		Outstanding Borrowings		Available Capacity
MPLX Credit Agreement(1)	$	3,500	$	—	$	3,500
MPC Loan Agreement	1,500		—		1,500
Total	$	5,000	$	—	5,000
Cash and cash equivalents					298
Total liquidity					$	5,298

(1)     Outstanding borrowings include less than $1 million in letters of credit outstanding under this facility. Our total capacity decreased to $2 billion upon the execution of the New MPLX Credit Agreement on July 7, 2022.

We expect our ongoing sources of liquidity to include cash generated from operations and borrowings under the MPC Loan Agreement, the New 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

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expenditure requirements, contractual obligations, and quarterly cash distributions. We may also, from time to time, repurchase our senior notes or preferred units in the open market, in tender offers, in privately negotiated transactions or otherwise in such volumes, at market prices and upon such other terms as we deem appropriate and execute unit repurchases under our unit repurchase program. 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.

Equity and Preferred Units Overview

Common units

The table below summarizes the changes in the number of units outstanding through June 30, 2022:

(In units)	Common Units
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	183,478
Units redeemed in unit repurchase program	(4,156,956)
Balance at June 30, 2022	1,012,204,900

Unit Repurchase Program

During the six months ended June 30, 2022, we repurchased approximately 4 million common units at an average cost per unit of $32.48 per unit and paid $135 million of cash. As of June 30, 2022, we had repurchased a total of approximately 29 million units at an average cost per unit of $27.97 per unit for a total of $798 million under the unit repurchase program. As of June 30, 2022, we had $202 million remaining under the existing repurchase authorization.

On August 2, 2022, MPLX announced the board of directors approved an incremental $1.0 billion unit repurchase authorization. The authorization has no expiration date. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, accelerated unit repurchases, tender offers or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing of repurchases will depend upon several factors, including market and business conditions, and repurchases may be discontinued at any time.

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 $266 million per quarter, or $1,063 million per year, based on the number of common units outstanding at June 30, 2022.

On July 26, 2022, MPLX declared a cash distribution for the second quarter of 2022, totaling $714 million, or $0.7050 per common unit. This distribution will be paid on August 12, 2022 to common unitholders of record on August 5, 2022. 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. This rate will also be received by Series A preferred unitholders.

Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the board of directors. Accordingly, a cash distribution payment totaling $21 million will be paid to Series B unitholders on August 15, 2022.

MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023. MPLX will pay unitholders the Series B preferred unit redemption price of $1,000 per unit plus any accumulated and unpaid distributions up to the redemption date.

The allocation of total cash distributions is as follows for the three and six months ended June 30, 2022 and 2021. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

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	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per unit data)	2022		2021		2022		2021
Distribution declared:
Limited partner units - public	$	257	$	260	$	514	$	522
Limited partner units - MPC	457		445		913		890
Total LP distribution declared	714		705		1,427		1,412
Series A preferred units	21		21		42		41
Series B preferred units	10		10		21		21
Total distribution declared	745		736		1,490		1,474
Quarterly cash distributions declared per limited partner common unit	$	0.7050	$	0.6875	$	1.4100	$	1.3750

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 acquisitions or capital improvements that we expect will increase our operating capacity for 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 costs to develop or acquire additional pipeline, terminal, processing or storage capacity. In general, growth capital includes costs that are expected to generate additional or new cash flow for MPLX.

MPLX’s initial capital investment plan for 2022, totaled $900 million which includes growth capital of $700 million, maintenance capital of $140 million and a $60 million investment in an unconsolidated affiliate for the repayment of our 9.19 percent indirect share of the Bakken Pipeline joint venture’s debt due in 2022. Growth capital expenditures and investments in affiliates during the six months ended June 30, 2022 were primarily for gas gathering, processing and de-ethanization projects in our Bakken, Marcellus, and Southwest basins and the expansion of our crude gathering systems and long-haul pipeline investments in the Permian and Bakken basins. Spending for the period also included the $60 million contribution to our Bakken Pipeline joint venture to fund our share of a debt repayment by the joint venture. We continuously evaluate our capital plan and make changes as conditions warrant.

Our capital expenditures are shown in the table below:

	Six Months Ended June 30,
(In millions)	2022		2021
Capital expenditures:
Growth capital expenditures	$	278	$	155
Investments in unconsolidated affiliates	156		84
Capitalized interest	(5)		(10)
Total growth capital expenditures(1)	429		229
Maintenance capital expenditures	70		46
Maintenance capital reimbursements	(17)		(17)
Total maintenance capital expenditures	53		29
Total growth and maintenance capital expenditures	482		258
Investments in unconsolidated affiliates(2)	(156)		(84)
Maintenance capital reimbursements(3)	17		17
(Increase)/ decrease in capital accruals	(54)		34
Capitalized interest	5		10
Additions to property, plant and equipment, net(2)	$	294	$	235

(1)    Total growth capital expenditures exclude $28 million of acquisitions for the six months ended June 30, 2022.    

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(2)    Investments in unconsolidated affiliates, acquisitions, and additions to property, plant and equipment, net are shown as separate lines within investing activities in the Consolidated Statements of Cash Flows.

(3)    Maintenance capital reimbursements are included in the Contributions from MPC line within financing activities in the Consolidated Statements of Cash Flows.

Contractual Cash Obligations

As of June 30, 2022, our contractual cash obligations included third-party and related party debt, finance and operating lease obligations, purchase obligations for services and to acquire property, plant and equipment, and other liabilities. During the six months ended June 30, 2022, our third-party long-term debt obligations increased by $1.2 billion, primarily due to the issuance of the $1.5 billion aggregate principal amount of 4.950 percent 2052 Senior Notes, discussed above. A portion of the issuance was used to repay amounts outstanding on the MPLX Credit Agreement. There were no other material changes to our contractual obligations outside the ordinary course of business since December 31, 2021.

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 15. Although these arrangements serve a variety of our business purposes, we are not dependent on them to maintain our liquidity and capital resources, and we are not aware of any circumstances that are reasonably likely to cause the off-balance sheet arrangements to have a material adverse effect on our liquidity and capital resources.

Transactions with Related Parties

At June 30, 2022, MPC owned our non-economic general partnership interest and held approximately 64 percent of our outstanding common units.

We provide MPC with crude oil and product pipeline and trucking transportation services based on regulated tariff/contracted rates, as well as storage, terminal, fuels distribution, and inland marine transportation services based on contracted rates. We also have agreements with MPC under which we receive fees for operating MPC’s retained pipeline assets, providing management services for the marine business, and operating certain of MPC’s equity method investments. MPC provides us with certain services related to information technology, engineering, legal, accounting, treasury, human resources and other administrative services under employee services and omnibus services agreements.

The below table shows the percentage of Total revenues and other income as well as Total costs and expenses with MPC:

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Total revenues and other income	45	%	47	%	46	%	52	%
Total costs and expenses(1)	23	%	27	%	24	%	28	%

(1)     2021 periods exclude losses for impairment.

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, 2021 and Note 4 of the Notes to the 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.

During the six months ended June 30, 2022, environmental remediation costs increased due to a release of crude oil on our pipeline near Edwardsville, Illinois in March of 2022. There have been no additional material changes to our environmental matters and compliance costs since our Annual Report on Form 10-K for the year ended December 31, 2021.

Critical Accounting Estimates

As of June 30, 2022, 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, 2021.

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Accounting Standards Not Yet Adopted

We have not identified any recent accounting pronouncements that are expected to have a material impact on our financial condition, results of operations or cash flows upon adoption. Accounting standards are discussed in Note 2 of the Notes to the Consolidated Financial Statements.

Item 3. Quantitative and Qualitative Disclosures about Market Risk

We are exposed to market risks related to the volatility of commodity prices. We employ various strategies, including the potential use of commodity derivative instruments, to economically hedge the risks related to these price fluctuations. We are also exposed to market risks related to changes in interest rates. As of June 30, 2022, we did not have any open financial or commodity derivative instruments to hedge the economic risks related to interest rate fluctuations or the volatility of commodity prices, respectively; however, we continually monitor the market and our exposure and may enter into these arrangements in the future.

Commodity Price Risk

The information about commodity price risk for the three and six months ended June 30, 2022 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, 2021.

Outstanding Derivative Contracts

See Notes 9 and 10 to the unaudited consolidated financial statements for more information about the fair value measurement of our natural gas embedded derivative, as well as the amounts recorded in our consolidated balance sheets and statements of income.

Interest Rate Risk and Sensitivity Analysis

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

(In millions)	Fair Value as of June 30, 2022(1)		Change in Fair Value(2)		Change in Income Before Income Taxes for the Six Months Ended June 30, 2022(3)
Outstanding debt
Fixed-rate	$	18,604	$	1,478	N/A
Variable-rate(4)	$	—	$	—	$	1

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

(2)    Assumes a 100-basis-point decrease in the weighted average yield-to-maturity at June 30, 2022.

(3)    Assumes a 100-basis-point change in interest rates. The change to net income was based on the weighted average balance of all outstanding variable-rate debt for the six months ended June 30, 2022.

(4)    MPLX had no outstanding borrowings on the MPLX Credit Agreement as of June 30, 2022.

At June 30, 2022, our portfolio of third‑party debt consisted of fixed-rate instruments and also provides for borrowings under the MPLX Credit Agreement. 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 MPLX Credit Agreement, but may affect our results of operations and cash flows.

See Note 9 to the unaudited consolidated financial statements for additional information on the fair value of our debt.

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

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upon that evaluation, the chief executive officer and chief financial officer of our general partner concluded that the design and operation of these disclosure controls and procedures were effective as of June 30, 2022, the end of the period covered by this report.

Changes in Internal Control Over Financial Reporting

During the quarter ended June 30, 2022, 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.

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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. While it is possible that an adverse result in one or more of the lawsuits or proceedings in which we are a defendant could be material to us, based upon current information and our experience as a defendant in other matters, we believe that these lawsuits and proceedings, individually or in the aggregate, will not have a material adverse effect on our consolidated results of operations, financial position or cash flows.

Item 103 of Regulation S-K promulgated by the SEC requires disclosure of certain environmental matters when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions, unless we reasonably believe that the matter will result in no monetary sanctions, or in monetary sanctions, exclusive of interest and costs, of less than $300,000.

There have been no material changes to the legal matters previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2021, or in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2022.

Item 1A. Risk Factors

There have been no material changes from the risk factors previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2021.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

The following table sets forth a summary of our purchases during the quarter ended June 30, 2022, of equity securities that are registered by MPLX pursuant to Section 12 of the Securities Exchange Act of 1934, as amended.

					Millions of Dollars
Period	Total Number of Units Purchased	Average Price Paid per Unit(1)		Total Number of Units Purchased as Part of Publicly Announced Plans or Programs	Maximum Dollar Value of Units that May Yet Be Purchased Under the Plans or Programs(2)
4/01/2022-4/30/2022	1,037,434	$	33.74	1,037,434	$	202
5/01/2022-5/31/2022	—	—		—	202
6/01/2022-6/30/2022	—	—		—	$	202
Total	1,037,434	$	33.74	1,037,434

(1)Amounts in this column reflect the weighted average price paid for units purchased under our unit repurchase authorization. The weighted average price includes commissions paid to brokers during the quarter.

(2)On November 2, 2020, we announced the board authorization of a unit repurchase program for the repurchase of up to $1 billion of MPLX’s common units held by the public. On August 2, 2022, we announced our board of directors had approved an additional $1 billion unit repurchase authorization, which is not reflected in this column. These unit repurchase authorizations have no expiration date.

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Item 6. Exhibits  

		Incorporated by Reference From
Exhibit Number	Exhibit Description	Form	Exhibit	Filing Date	SEC File No.	Filed Herewith	Furnished Herewith
3.1	Certificate of Limited Partnership of MPLX LP	S-1	3.1	7/2/2012	333-182500
3.2	Amendment to the Certificate of Limited Partnership of MPLX LP	S-1/A	3.2	10/9/2012	333-182500
3.3	Sixth Amended and Restated Agreement of Limited Partnership of MPLX LP, dated as of February 1, 2021	8-K	3.1	2/3/2021	001-35714
10.1	Master Amendment to Transportation Services Agreements, dated as of June 30, 2022, by and among Marathon Petroleum Company LP, Marathon Petroleum Supply and Trading LLC, Marathon Pipe Line LLC and Ohio River Pipe Line LLC	8-K	10.1	7/6/2022	001-35714
10.2	Revolving Credit Agreement, dated as of July 7, 2022, by and among MPLX LP, as borrower, Wells Fargo Bank, National Association, as administrative agent, each of Wells Fargo Securities, LLC, JPMorgan Chase Bank, N.A., Barclays Bank PLC, BofA Securities, Inc., Citibank, N.A., Mizuho Bank, Ltd., MUFG Bank, Ltd., RBC Capital Markets and TD Securities (USA) LLC, as joint lead arrangers and joint bookrunners, JPMorgan Chase Bank, N.A., as syndication agent, each of Bank of America, N.A., Barclays Bank PLC, Citibank, N.A., Mizuho Bank, Ltd., MUFG Bank, Ltd., Royal Bank of Canada and The Toronto-Dominion Bank, New York Branch, as documentation agents, and the other lenders and issuing banks that are parties thereto	8-K	10.1	7/12/2022	001-35714
10.3	Seventh Amendment to Third Amended and Restated Terminal Services Agreement, dated March 1, 2017, between MPLX Terminals LLC and Marathon Petroleum Company LP					X
31.1	Certification of Chief Executive Officer pursuant to Rule 13a-14 and 15d-14 under the Securities Exchange Act of 1934					X
31.2	Certification of Chief Financial Officer pursuant to Rule 13a-14 and 15d-14 under the Securities Exchange Act of 1934					X
32.1	Certification of Chief Executive Officer pursuant to 18 U.S.C. Section 1350						X
32.2	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

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		Incorporated by Reference From
Exhibit Number	Exhibit Description	Form	Exhibit	Filing Date	SEC File No.	Filed Herewith	Furnished Herewith
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).

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SIGNATURES

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

	MPLX LP
	By:	MPLX GP LLC
		Its general partner
Date: August 2, 2022	By:	/s/ Kelly D. Wright
		Kelly D. Wright
		Vice President and Controller of MPLX GP LLC (the general partner of MPLX LP)

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EX-10.3

Exhibit 10.3

Seventh Amendment to the Third Amended and Restated Terminal Services Agreement

This Seventh Amendment to the Third Amended and Restated Terminal Services Agreement ("Amendment") is dated as of May 20,2022, by and between Marathon Petroleum Company LP, a Delaware limited partnership with an address of 539 South Main Street, Findlay, Ohio 45840 ("MPC"), and MPLX Terminals LLC, a Delaware limited liability company with an address of 200 East Hardin Street, Findlay, Ohio 45840 ("Terminal Owner"). Each of MPC and Terminal Owner shall be referred to herein individually as a "Party" or collectively as the "Parties."

    WHEREAS, MPC and Terminal Owner are Parties to that certain Third Amended and Restated Terminal Services Agreement, dated March 1, 2017, as amended on September 1, 2017, October 31, 2017, March 20, 2018, July 1, 2019, December 13, 2019, and September 28, 2020 (as amended, the “Agreement”); and

WHEREAS, MPC and Terminal Owner desire to amend the Agreement to update Schedule 3.1 and Schedule 5.1.

NOW, THEREFORE, in consideration of the forgoing and for other goods and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree that the foregoing recitals are incorporated herein by reference and as follows:

1.    Except for the provisions of the Agreement specifically addressed in this Amendment, all other provisions of the Agreement shall remain in full force and effect.

2.    Capitalized terms used but not defined in this Amendment shall have the meaning ascribed to such terms in the Agreement.

3.    Schedule 3.1 of the Agreement is hereby deleted in its entirety and replaced with the attached Schedule 3.1.

4.    Schedule 5.1 of the Agreement is hereby deleted in its entirety and replaced with the attached Schedule 5.1.

5.    The Minimum Quarterly Terminal Volume Commitments for the Charlotte (East), Jacksonville, Florida, Mt. Prospect, Illinois and Rockford, Illinois terminals for the second quarter of 2022 will be prorated to the effective date of this Amendment.

6.    The effective date of this Amendment is May 20,2022.

7.    This Amendment constitutes the entire agreement among the Parties regarding this subject matter and may be amended or modified only by a written instrument signed by each of the Parties and supersedes any other prior agreements or understandings of the Parties relating to this subject matter and the Parties are not relying on any statement, representation, promise or inducement not expressly set forth herein.

8.    This Amendment may be executed in one or more counterparts, and in both original form and one or more photocopies, each of which shall be deemed to be an original, but all of which together shall be deemed to constitute one and the same instrument.

IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be executed by their respective authorized representatives.

Marathon Petroleum Company LP			MPLX Terminals LLC
By: MPC Investment LLC, its General Partner
By:	/s/ P. A. Melton	By:	/s/ L. A. Wilkins
Name:	P. A. Melton	Name:	L. A. Wilkins
Title:	Vice President	Title:	President

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Schedule 3.1 - Terminals and Minimum Quarterly Terminal Volume Commitments

Terminal Name	State	Region	Facility Type	Loading Hours	Gallons	RC Assets
						Lanes	Docks	Shell Capacity
Bay City	MI	MW	Pipeline	24/7	71,625,000	3		437,600
Bellevue	OH	MW	Pipeline	24/7	5,664,000	1		-
Belton	SC	SE	Pipeline	24/7	74,949,000	3		370,500
Birmingham	AL	SE	Pipeline	24/7	58,131,000	2		251,000
Brecksville	OH	MW	Pipeline	24/7	30,912,000	2		454,800
Canton	OH	MW	Refinery	24/7	159,134,000	6		48,500
Champaign	IL	MW	Pipeline	24/7	96,441,000	4		554,500
Charleston	WV	MW	Barge	24/7	36,360,000	2	1	165,700
Charlotte (East)	NC	SE	Pipeline	24/7	110,751,000	4		451,800
Cincinnati	OH	MW	Barge	24/7	54,021,000	2	1	438,700
Columbus (East & West)	OH	MW	Pipeline	24/7	197,481,000	4		749,700
Columbus (GA)	GA	SE	Pipeline	24/7	22,335,000	1		132,600
Covington	KY	MW	Barge	24/7	100,056,000	4	1	342,100
Detroit	MI	MW	Refinery	24/7	260,460,000	6		-
Doraville	GA	SE	Pipeline	24/7	52,626,000	2		217,100
Evansville	IN	MW	Barge	24/7	37,686,000	2	1	104,100
Flint	MI	MW	Pipeline	24/7	37,401,000	2		223,800
Ft. Lauderdale (Eisenhower)	FL	SE	Marine	24/7	112,170,000	4	1	559,900
Ft. Lauderdale (Spangler)	FL	SE	Marine	24/7	107,451,000	3	1	473,800
Garyville	LA	SE	Refinery	24/7	61,788,000	2		96,700
Greensboro (Guilford County)	NC	SE	Pipeline	24/7	78,170,000			414,700
Hammond	IN	MW	Pipeline	24/7	117,831,000	3		1,193,800
Heath	OH	MW	Pipeline	24/7	49,524,000	2		11,100
Huntington	IN	MW	Pipeline	24/7	35,220,000	2		187,000
Indianapolis	IN	MW	Pipeline	24/7	64,806,000	3		951,600
Jackson	MI	MW	Pipeline	24/7	21,828,000	2		263,700
Kenova/Catlettsburg Docks	WV/KY	MW	Marine Docks	24/7	712,500,000		4	1,421,100
Knoxville	TN	SE	Pipeline	24/7	77,520,000	4		332,800
Lansing	MI	MW	Pipeline	24/7	59,682,000	3		174,700
Lexington	KY	MW	Pipeline	24/7	79,470,000	3		205,300
Lima	OH	MW	Pipeline	24/7	92,961,000	2		819,100
Louisville (Algonquin)	KY	MW	Barge	24/7	202,890,000	6	1	1,215,400
Louisville (Kramers)	KY	MW	Barge	24/7	115,401,000	4	1	558,300
Macon	GA	SE	Pipeline	24/7	79,296,000	3		294,200
Marietta	OH	MW	Barge	24/7	46,947,000	3	2	170,700
Midland	PA	MW	Barge	24/7	54,573,000	2	1	390,400
Montgomery	AL	SE	Pipeline	24/7	53,745,000	2		191,700
Mt. Vernon	IN	MW	Barge	24/7	105,945,000	1	1	595,000
Muncie	IN	MW	Pipeline	24/7	42,747,000	2		232,600
Nashville (Bordeaux)	TN	SE	Pipeline	24/7	64,008,000	3	1	233,800
Nashville (Downtown)	TN	SE	Barge	24/7	44,289,000	2	1	250,800
Nashville (51st)	TN	SE	Pipeline	24/7	60,903,000	3		331,100
Niles	MI	MW	Pipeline	24/7	74,589,000	2		631,100
North Muskegon	MI	MW	Pipeline	24/7	113,175,000	5		440,200
Oregon	OH	MW	Pipeline	24/7	53,250,000	2		247,800

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Paducah	KY	MW	Barge	24/7	30,654,000	2	1	208,300
Powder Springs	GA	SE	Pipeline	24/7	78,300,000	3		338,300
Robinson	IL	MW	Refinery	24/7	74,736,000	4		7,300
Romulus	MI	MW	Pipeline	24/7	27,309,000	3		268,400
Selma (Buffalo)	NC	SE	Pipeline	24/7	123,750,000	3		549,000
Selma (West Oak)	NC	SE	Pipeline	24/7	99,537,000	4		355,000
Speedway	IN	MW	Pipeline	24/7	124,647,000	5		526,300
Steubenville	OH	MW	Pipeline	24/7	16,599,000	2		128,100
Tampa	FL	SE	Marine	24/7	334,203,000	10	1	1,231,700
Viney Branch	KY	MW	Refinery	24/7	114,474,000	6		57,100
Youngstown	OH	MW	Pipeline	24/7	28,176,000	2		131,000

Terminal Complexes:

1.    Brecksville and Canton

2.    Cincinnati and Covington

3.    Evansville and Mt. Vernon

4.    Ft. Lauderdale (Spangler) and Ft. Lauderdale (Eisenhower)

5.    Indianapolis and Speedway

6.    Louisville (Kramers) and Louisville (Algonquin)

7.    Nashville (Bordeaux), Nashville (Downtown) and Nashville (51st)

8.    Selma (Buffalo) and Selma (West Oak)

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Schedule 5.1 – Fees

Terminal Name	Base Throughput Fee*	Excess Throughput Fee*
Bay City	0.01734290	0.01430226
Bellevue	0.01407703	0.01407703
Belton	0.01531581	0.01351395
Birmingham	0.01587889	0.01362657
Brecksville	0.03513627	0.01407703
Canton	0.01407703	0.01407703
Champaign	0.01497796	0.01407703
Charleston	0.02432511	0.01452750
Charlotte (East)	0.01554104	0.01385180
Cincinnati	0.03130732	0.01452750
Columbus (GA)	0.02894237	0.01373918
Columbus (OH)	0.01317610	0.01317610
Covington	0.01756813	0.01723029
Detroit LP	0.01407703	0.01407703
Doraville	0.02083400	0.01373918
Evansville	0.02207278	0.01475273
Flint	0.02432511	0.01418965
Ft. Lauderdale (Eisenhower)	0.01891953	0.01418965
Ft. Lauderdale (Spangler)	0.01520319	0.01520319
Garyville	0.01486534	0.01317610
Greensboro (Friendship)	0.01351395	0.01351395

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Hammond	0.02038354	0.01328872
Heath	0.01295087	0.01295087
Huntington	0.02049616	0.01430226
Indianapolis	0.02804144	0.01430226
Jackson	0.04189324	0.01430226
Kenova (Catlettsburg Docks)	0.00732006	0.00732006
Knoxville	0.01385180	0.01340133
Lansing	0.01587889	0.01430226
Lexington	0.01418965	0.01385180
Lima	0.01936999	0.01295087
Louisville (Algonquin)	0.01970784	0.01351395
Louisville (Kramers)	0.01677982	0.01418965
Macon	0.01497796	0.01317610
Marietta	0.02286110	0.01452750
Midland	0.02646482	0.01272564
Montgomery	0.01745552	0.01362657
Mt. Vernon	0.01790598	0.01238779
Muncie	0.01801860	0.01407703
Nashville (51st)	0.01858168	0.01362657
Nashville (Bordeaux)	0.01565366	0.01362657
Nashville (Downtown)	0.02218540	0.01362657
Niles	0.02015831	0.01396441
North Muskegon	0.01430226	0.01430226
Oregon	0.01813121	0.01407703

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Paducah	0.02871714	0.01407703
Powder Springs	0.01644197	0.01373918
Robinson	0.01475273	0.01373918
Romulus	0.03930307	0.01441488
Selma (Buffalo)	0.01373918	0.01373918
Selma (West Oak)	0.01373918	0.01373918
Speedway	0.01430226	0.01430226
Steubenville	0.03389749	0.01396441
Tampa	0.01542843	0.01430226
Viney Branch	0.01418965	0.01418965
Youngstown	0.02455034	0.01362657

*The table above reflects the fees effective as of January 1, 2022, as adjusted per Section 5.3.

Marine Docks

Kenova/Catlettsburg Docks includes Kenova Light Product, and Catlettsburg Crude, Heavy Oil, and

Light Oil Docks

Kenova/Catlettsburg Docks - $2,815,406 per month (reflects monthly fee effective as January 1, 2022, as adjusted per Section 5.3).

Butane/Natural Gasoline/Pentane Blending

A)    Facilities with Third Party Licensed Blending Technology

From and after July 1, 2019, at facilities at which Energy Transfer Partners LP (“ETP”) licenses blending technology to MPC, Terminal Owner's fee for performing the butane blending service shall be calculated as follows:

Ninety-five percent (95%) of the difference between the Daily Gasoline Value (defined below) and the Daily Butane Value (defined below). Expressed as a formula, the Butane Blending Service Fee is:

Butane Blending Service Fee = (DGV-DBV)* 95%

NOTE: Terminal Owner will reflect an Annual True-Up, as defined in Section 4 of this Schedule 5.1, as a separate line item on any monthly invoices submitted pursuant to this Agreement.

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Definitions:

1. Daily Gasoline Value ("DGV"): Expressed as a formula:

DGV = (GB)*(GPV+TF)

GB: number of Gallons of butane blended on a given day at the terminal site.

GPV: daily gasoline posted value per Gallon.

TF: the transportation fee for moving spot purchased gasoline to the terminal for the gasoline grade in which the butane is blended.

a. GPV is calculated by location as follows:

Location	Market	GPV Price Calculation
Bay City	Chicago	Daily posted Argus 85 CBOB and 91 PREM spot prices
Charlotte East	Gulf Coast	Daily posted Argus 85 CBOB and 91 PREM spot prices
Lansing	Chicago	Daily posted Argus 85 CBOB and 91 PREM spot prices
Nashville 51st	Gulf Coast	Daily posted Argus 85 CBOB and 91 PREM spot prices
Selma Buffalo	Gulf Coast	Daily posted Argus 85 CBOB and 91 PREM spot prices
Selma Oak	Gulf Coast	Daily posted Argus 85 CBOB and 91 PREM spot prices
Speedway	Chicago	Daily posted Argus 85 CBOB and 91 PREM spot prices
North Muskegon	Chicago	Daily posted Argus 85 CBOB and 91 PREM spot prices
Tampa	Gulf Coast	Daily posted Argus 85 CBOB and 91 PREM spot prices

b. TF is the avoided MPC cost of transporting one Gallon of gasoline (in the most cost effective method possible) to a terminal blending location, as verified and provided by MPC's Supply Distribution & Planning - Light Products Project Analysis organization.

2. Daily Butane Value ("DBV"): the daily agreed upon butane purchase price ("BPP") from ETP plus the total daily RIN value (“DRV”), multiplied by the daily total number of butane gallons blended ("GB"). Expressed as a formula:

DBV = (GB)*(BPP+DRV)

Bay City DBV = (GB)*(BPP+1/2DRV)

a. DRV will be determined by using the percentage of each type of RINs specified by the Renewable Fuel Standard Program updated annually or the most recent requirements and will be adjusted retroactively for any difference between the requirements at the time of the calculation and the requirements contained in a

8

final rule establishing Renewable Volume Obligations for the year. OPIS daily posting for the respective RINs pricing will be used. In order to minimize the daily average RINs Cost, postings for prior year’s RINs will be used up to the maximum allowable percentage.

3. Profit Sharing Payment: For each calendar month, a Profit Sharing Payment (“PSP”) is paid by ETP to MPC for volumes blended at the Bay City terminal. The PSP is calculated as the volume of gallons blended (“GB”) at Bay City in such month multiplied by fifty percent multiplied by the following value: (A) the volume weighted daily average of the high and low assessments of Argus posted Chicago Cycle 1 gasoline price (85 CBOB) minus (B) the volume weighted daily average of the high and low assessments of the OPIS posted Mt. Belvieu TET normal butane price minus (C) the average supply cost.

Fee calculations pursuant to this Schedule 5.1 for butane blending services completed prior to July 1, 2019 shall not be affected by changes in the foregoing formulas.

4. Annual True-Up: This cost or revenue is intended to cover changes in the estimated vs actual transportation costs, half of shared maintenance expenses, and estimated vs actual butane purchase costs. The cost or revenue is calculated ETP. MPC will pass ninety-five percent (95%) of this to Terminal Owner.

B)    Facilities Without Third Party Blending Technology

From and after September 1, 2018, at facilities at which no third party licensed blending technology is utilized, Terminal Owner’s fee for performing the butane or pentane blending service shall be calculated as follows:

Ninety-five percent (95%) of the difference between the Tank Daily Gasoline Value (defined below) and the Tank Daily Butane Value (defined below). Expressed as a formula, the Tank Butane Blending Service Fee is:

            Tank Butane Blending Service Fee = (TDGV-TDBV)* 95%

            Or

Ninety-five percent (95%) of the difference between the Tank Daily Gasoline Value (defined below) and the Tank Daily Pentane Value (defined below). Expressed as a formula, the Tank Pentane Blending Service Fee is:

            Tank Pentane Blending Service Fee = (TDGV-TDPV)* 95%

Definitions:

1.    Tank Daily Gasoline Value (“TDGV”): Expressed as a formula:

TDGV = (GB)*(GPV+TF)

    GB: number of Gallons of butane blended on a given day at the terminal site.

    GPV: daily gasoline posted value per gallon.

TF: the avoided transportation fee for moving spot purchased gasoline to the terminal for the gasoline grade in which the butane is blended.

a.    GPV is calculated by location using the daily posted average Argus 85 CBOB or Argus PREM spot prices for the respective blend and market derived from Schedule 3.1.

9

2.    Tank Daily Butane Value (“TDBV”): the daily agreed upon tank butane purchase price (“TBPP”) from supplier, plus the total daily RIN value (“DRV”), multiplied by the daily total number of butane Gallons blended (“GB”). Expressed as a formula:

TDBV = (GB)*(TBPP+DRV+TC)

a.    TC is the trucking cost of transporting one Gallon of butane (in the most cost effective method possible) to a terminal blending location.

b.    DRV will be determined by using the percentage of each type of RINs specified by the Renewable Fuel Standard Program updated annually to the most recent requirements and will be adjusted retroactively for any difference between the requirements at the time of the calculation and the requirements contained in a final rule establishing Renewable Volume Obligations for the year. OPIS daily posting for the respective RINs pricing will be used. In order to minimize the daily average RINs Cost, posting for prior year’s RINs will be used up to the maximum allowable percentage.

3.    Tank Daily Pentane Value (“TDPV”): the daily agreed upon tank pentane purchase price (“TPPP”) from supplier, plus the total daily RIN value (“DRV”), multiplied by the daily total number of butane Gallons blended (“GB”). Expressed as a formula:

TDPV = (GB) * (TPPP + DRV + TC)

a.    TC is the trucking costs of transporting one Gallon of pentane (in the most cost-effective manner) to a terminal blending location.

b.     DRV will be determined by using the percentage of each type of RINs specified by the Renewable Fuel Standard Program updated annually or the most recent requirements and will be adjusted retroactively for any difference between the requirements at the time of the calculation and the requirements contained in a final rule establishing Renewable Volume Obligations for the year. OPIS daily posting for the respective RINs pricing will be used. In order to minimize the daily average RINs Cost, postings for the prior year’s RINs will be used up to the maximum allowable percentage.

4.    In the event MPC requests a butane skid for temporary use at an MPC owned terminal(s), MPC shall pay an MPLX Tank Butane Blending Equipment Service Fee equal to 5% of the blending value. Expressed as a formula:

a.    MPLX Tank Butane Blending Equipment Service Fee = (TDGV-TDBV)* 5%.

5.    Annual Adjustment to Revenue: This cost or revenue is intended to cover changes in the estimated vs actual transportation costs. Annually during the month of April, MPC will issue an adjustment of revenue to MPLX. This adjustment will be the result in changes of actual vs previously estimated trucking costs associated with delivery of butane to the terminals for the previous April- March.

C)    Kenova Blending

From and after October 31st, 2019, at the Kenova, WV terminal the Terminal Owner’s fee for performing in-line or barge loading blending service shall be calculated as follows:

Ninety-five percent (95%) of the difference between the Marathon Daily Gasoline Value (defined below) and the Marathon Daily Butane Value (defined below) or the Marathon

10

Daily Pentane Value (defined below). Expressed as a formula the Inline or Barge Blending Service Fee is:

Inline or Barge Blending Service Fee = (MDGV – MDBV) * 0.95

Or

Inline or Barge Blending Service Fee = (MDGV – MDPV) * 0.95

Definitions:

1.    Marathon Daily Gasoline Value (“MDGV”): Expressed as a formula:

MDGV = (GB) * (GPV + KTF)

    GB: Number of Gallons of butane/pentane blended on a given day at the terminal site.

    GPV: daily gasoline posted value per Gallon

    KTF: the additional transportation costs for moving the gasoline barrel produced through butane or pentane blending to the terminal of sale

a.    GPV is calculated by the location using the daily posted averages of either Argus 85 CBOB or Argus Prem spot prices for the respective blend and market derived from Schedule 3.1

2.    Marathon Daily Butane Value (“MDBV”): the daily agreed upon Marathon butane purchase price (“MBPP”) from supplier, plus the total daily RIN value (“DRV”), multiplied by the daily total number of butane Gallons blended (“GB”). Expressed as a formula:

MDBV = (GB) * (MBPP + DRV + TC)

a.    TC is the trucking costs of transporting one Gallon of butane (in the most cost-effective manner) to a terminal blending location.

b.    DRV will be determined by using the percentage of each type of RINs specified by the Renewable Fuel Standard Program updated annually or the most recent requirements and will be adjusted retroactively for any difference between the requirements at the time of the calculation and the requirements contained in a final rule establishing Renewable Volume Obligations for the year. OPIS daily posting for the respective RINs pricing will be used. In order to minimize the daily average RINs Cost, postings for the prior year’s RINs will be used up to the maximum allowable percentage.

3.    Marathon Daily Pentane Value (“MDPV”): the daily agreed upon Marathon pentane purchase price (“MPPP”) from supplier, plus the total daily RIN value (“DRV”), multiplied by the daily total number of butane Gallons blended (“GB”). Expressed as a formula:

MDPV = (GB) * (MPPP + DRV + TC)

a.    TC is the trucking costs of transporting one Gallon of pentane (in the most cost-effective manner) to a terminal blending location.

b.    DRV will be determined by using the percentage of each type of RINs specified by the Renewable Fuel Standard Program updated annually or the most recent requirements and will be adjusted retroactively for any difference between the requirements at the time of the calculation and the requirements contained in a final rule establishing Renewable Volume Obligations for the year. OPIS daily posting for the respective RINs pricing will be used. In order to minimize the daily average

11

RINs Cost, postings for the prior year’s RINs will be used up to the maximum allowable percentage.

D) Butane Blending into Natural Gasoline at Facilities Without Third Party Licensed Blending Technology

a. Butane Blending into Natural Gasoline Project Service Fee: Prior to MPC requesting Terminal Owner to provide natural gasoline blending services at a Terminal that does not have butane blending into natural gasoline service capabilities, MPC will pay a one-time fee to Terminal Owner as reimbursement for the project capital costs to be incurred by a Terminal to enable such Terminal to provide butane blending into natural gasoline services, as well as an additional charge of 15% of such project capital costs. Prior to any Terminal incurring any project capital costs to be able to provide butane blending into natural gasoline services for MPC, the Parties will agree upon the Butane Blending into Natural Gasoline Project Services Fee for each Terminal providing such services.

b. Butane Blending into Natural Gasoline Services Fee: From and after August 20th, 2019 at any Terminal with no third-party licensed blending technology utilized, Terminal Owner’s fee for performing butane blending into natural gasoline services shall be calculated as follows, expressed as a formula:

Natural Gas Blending Services Fee = $1.58 * the number of barrels of butane blended into natural gasoline

Ethanol Denaturing

$0.02 per Gallon of undenatured ethanol.

Unit Train Ethanol Receipts

Beginning on January 15, 2017 and continuing thereafter for so long as the Master Terminal Services Agreement by and between MPC and ECO Energy Distribution Services, LLC dated October 19, 2015 (the "ECO Agreement") has not terminated, been cancelled or otherwise expired pursuant to its terms or agreement of the parties thereto, each of the following shall apply:

1. MPC shall pay Terminal Owner $0.0135 per Gallon for Unit Train Ethanol Receipts; provided that the invoice for the month ending March 31 of each year (or upon termination of the ECO Agreement, prorated according to the time of such termination) shall include an additional fee of $0.0135 per Gallon of Unit Train Ethanol Receipts that are less than 111,360,000 Gallons for the 12-month period ending on March 31 of the same year (prorated for the time period between January 15, 2017 through March 31, 2017. The $0.0135 per Gallon fee set forth in this Section shall be adjusted at the time of and in an amount equal to any adjustment to the Throughput Fees (as defined in the ECO Agreement) pursuant to Section 6.l(b) of the ECO Agreement, as may be amended from time to time.

At the end of each Calendar Quarter, Terminal Owner shall credit MPC on the monthly invoice (or upon termination of the ECO Agreement, prorated according to the time of such termination) an amount equal to the sum of (a) the Base Throughput Fee for Selma (Buffalo) set forth in Schedule 5.1 (as adjusted) multiplied by the volume (in Gallons) of ethanol redelivered by truck from the Selma (Buffalo) Terminal to the Selma (West Oak) Terminals during such Calendar Quarter; and (b) the Base Throughput Fee for Selma (Buffalo) set forth in Schedule 5.1 (as

12

adjusted) multiplied by the volume (in Gallons) of ethanol redelivered per MPC's direction from the Selma (Buffalo) Terminal into trucks for ECO during such Calendar Quarter.

Ethanol Excess Volume Value Capture

MPC will pay Terminal Owner fees as calculated herein for EV at Terminals where sales volume is made on a temperature corrected basis.

The value will be calculated via the following method: Multiply the volume by the price per the calculations described in the following two paragraphs.

The volume will be calculated via the following method: The American Petroleum Institute’s Manual of Petroleum Measurement Standards Chapter 11.3.4 “Miscellaneous Hydrocarbon Properties – Denatured Ethanol and Gasoline Blend Densities and Volume Correction Factors” (“Chapter 11.3.4”) provides data-based equations for Blends of Gasoline and Ethanol (“BGE”). Chapter 11.3.4 addresses excess volumes of gasohol (“EV”) created when gasoline and ethanol components are blended together. EV for truck rack throughput at Terminals equipped with Terminal Automation Software (TAS) will be calculated using the equation in Chapter 11.3.4 performed by TAS for any BGE. The TAS will be programmed to calculate EV by multiplying these BGE volumes by the correction factors as calculated using the equation from Chapter 11.3.4. This process of crediting Terminal Owner with the EV based on the technology Terminal Owner installed and maintains at its Terminals is known as “Ethanol Excess Volume Value Capture.”

The price will be calculated via the following method: Each Terminal is assigned to the CHICAGO (Midwest-designated as ‘MW’) or US GULF COAST (Southeast-designated as ‘SE’) region based on Schedule 3.1. EV credited to Terminal Owner will be valued using the non-weighted monthly average ARGUS 85 Assessment MID CBOB price for given market based on the location of the Terminal. The Midwest (‘MW’) will be using West Shore and Gulf Coast (‘SE’) will be using Pasadena posted pricing.

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EX-31.1

Exhibit 31.1

CERTIFICATION PURSUANT TO SECTION 302 OF

THE SARBANES-OXLEY ACT OF 2002

I, Michael J. Hennigan, certify that:

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

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

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

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

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

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

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

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

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

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

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

Date: August 2, 2022	/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, John J. Quaid, certify that:

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

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

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

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

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

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

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

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

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

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

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

Date: August 2, 2022	/s/ John J. Quaid
	John J. Quaid
	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 quarter ended June 30, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael J. Hennigan, Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC, the general partner of the Partnership, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

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

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

Date: August 2, 2022

/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 quarter ended June 30, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, John J. Quaid, Executive Vice President and Chief Financial Officer of MPLX GP LLC, the general partner of the Partnership, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

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

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

Date: August 2, 2022

/s/ John J. Quaid

John J. Quaid

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

XML

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Jul. 29, 2022
Document Information [Line Items]
Document Transition Report	false
Document Quarterly Report	true
Title of 12(b) Security	Common Units Representing Limited Partnership Interests
Entity Incorporation, State or Country Code	DE
Document Type	10-Q
Document Period End Date	Jun. 30, 2022
Amendment Flag	false
Entity File Number	001-35714
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Trading Symbol	MPLX
Entity Registrant Name	MPLX LP
Entity Central Index Key	0001552000
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		1,012,204,900
Entity Address, Address Line One	200 E. Hardin Street,
Entity Address, City or Town	Findlay,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45840
City Area Code	419
Local Phone Number	421-2414
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Security Exchange Name	NYSE
Entity Tax Identification Number	27-0005456

XML

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income from equity method investments		$ 111	$ 66	$ 210	$ 136
Other Income		6	3	(11)	4
Related Party Transaction, Other Revenues from Transactions with Related Party		27	27	54	55
Revenues		2,940	2,395	5,550	4,734
Purchases - related parties		351	297	670	595
Cost, Depreciation and Amortization	[1]	310	318	623	647
General and Administrative Expense		82	87	160	173
Taxes, Miscellaneous		33	34	67	66
Costs and Expenses		1,823	1,464	3,373	2,829
Interest And Other Financial Costs From Related Parties		1	2	5	2
Other Nonoperating Income (Expense)		20	19	40	46
Interest Expense, Debt, Excluding Amortization		212	195	410	393
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent, Total		1,117	931	2,177	1,905
Provision for income taxes		0	0	5	1
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total		884	715	1,722	1,464
Less: Net income (loss) attributable to noncontrolling interest		9	9	17	18
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total		884	715	1,717	1,463
Limited partners' interest in net income (loss) attributable to MPLX LP		844	675	1,637	1,383
Net income (loss) attributable to MPLX LP	[2]	$ 875	$ 706	$ 1,700	$ 1,445
Net income (loss) attributable to MPLX LP per limited partner unit:
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax		$ 0.83	$ 0.66	$ 1.61	$ 1.34
Common - diluted (in USD per unit)		$ 0.83	$ 0.66	$ 1.61	$ 1.34
Weighted average limited partner units outstanding:
Common - basic (in shares)		1,012	1,029	1,013	1,033
Common - diluted (in shares)		1,012	1,029	1,014	1,033
Asset Impairment Charges		$ 0	$ 42	$ 0	$ 42
Third Party [Member]
Operating Lease, Lease Income		102	99	193	198
Direct Costs of Leased and Rented Property or Equipment		42	32	79	64
Service [Member] | Third Party [Member]
Total revenues from contracts with customers		577	578	1,131	1,167
Service, Other [Member]
Total revenues from contracts with customers		118	76	241	153
Product [Member] | Third Party [Member]
Total revenues from contracts with customers		698	304	1,195	586
Oil and Gas, Refining and Marketing [Member]
Cost of Goods and Services Sold		323	293	610	566
Natural Gas, Midstream [Member]
Cost of Goods and Services Sold		663	338	1,130	614
Series A Preferred Stock [Member] | Preferred Partner [Member]
Dividends, Preferred Stock		21	21	42	41
Net income (loss) attributable to MPLX LP	[2]	25	21	48	41
Series B Preferred Stock [Member] | Preferred Partner [Member]
Dividends, Preferred Stock		10	10	21	21
Net income (loss) attributable to MPLX LP	[2]	10	10	21	21
Affiliated Entity
Sales-type Lease, Revenue		114	136	225	173
Operating Lease, Lease Income, Related Party		198	168	363	410
Direct costs of leased and rented property or equipment, related parties		19	23	34	62
Affiliated Entity | Service [Member]
Total revenues from contracts with customers		938	907	1,853	1,779
Affiliated Entity | Product [Member]
Total revenues from contracts with customers		$ 51	$ 31	$ 96	$ 73

[1] Depreciation and amortization attributable to L&S was $129 million and $259 million for the three and six months ended June 30, 2022, respectively, and $136 million and $283 million for the three and six months ended June 30, 2021, respectively. Depreciation and amortization attributable to G&P was $181 million and $364 million for the three and six months ended June 30, 2022, respectively, and $182 million and $364 million for the three and six months ended June 30, 2021, respectively.

[2] 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

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Interest Costs Capitalized	$ 3	$ 5	$ 5	$ 10

XML

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 884	$ 715	$ 1,717	$ 1,463
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	0	9	(2)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total	884	715	1,726	1,461
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest [Abstract]
Less: Net income (loss) attributable to noncontrolling interest	9	9	17	18
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 875	$ 706	$ 1,709	$ 1,443

XML

Consolidated Balance Sheets - USD ($) shares in Millions, $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 298	$ 13
Receivables, net	789	654
Inventories	157	142
Total current assets	2,018	1,507
Equity method investments	4,099	3,981
Property, plant and equipment, net	19,767	20,042
Intangibles, net	768	831
Goodwill	7,645	7,657
Other noncurrent assets	49	60
Total assets	35,788	35,507
Liabilities
Accounts Payable, Current	352	172
Accrued Liabilities, Current	415	363
Accrued Property Plant and Equipment Current	104	97
Long-term Debt and Lease Obligation, Current	1,000	499
Interest Payable, Current	224	202
Other current liabilities	198	176
Total current liabilities	2,741	3,348
Long-term debt	18,775	18,072
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	14	10
Other long-term liabilities	167	170
Total liabilities	22,679	22,490
Commitments and contingencies (see Note 15)
Equity
Accumulated other comprehensive loss	(8)	(17)
Total MPLX LP partners’ capital	11,905	11,811
Noncontrolling interests	239	241
Total equity	12,144	12,052
Total liabilities, preferred units and equity	35,788	35,507
Third Party [Member]
Assets
Other current assets	43	54
Operating Lease, Right-of-Use Asset	300	268
Liabilities
Operating Lease, Liability, Current	45	59
Long-term deferred revenue	429	383
Operating Lease, Liability, Noncurrent	250	205
Affiliated Entity
Assets
Current Assets, Related Parties	731	644
Other current assets	2	3
Operating Lease, Right-of-Use Asset	229	229
Due from Related Parties, Noncurrent	1,142	1,161
Liabilities
Due to Related Parties, Current	403	1,780
Operating Lease, Liability, Current	1	1
Liabilities, Related Parties, Noncurrent	303	302
Operating Lease, Liability, Noncurrent	$ 228	$ 228
Series B Preferred Stock [Member]
Liabilities
Preferred Units, Issued	0.6	0.6
Preferred Units, Outstanding	0.6	0.6
Equity
Preferred Units, Preferred Partners' Capital Accounts	$ 611	$ 611
Limited Partners Common Units [Member] | Public [Member]
Liabilities
Units issued	365.0	369.0
Equity
Limited Partners' Capital Account	$ 8,518	$ 8,579
Units Outstanding	365.0	369.0
Limited Partners Common Units [Member] | Marathon Petroleum Corporation [Member]
Liabilities
Units issued	647.0	647.0
Equity
Limited Partners' Capital Account	$ 2,784	$ 2,638
Units Outstanding	647.0	647.0
Series A Convertible Preferred Units
Liabilities
Preferred Units, Issued	30.0	30.0
Preferred Units, Outstanding	30.0	30.0
Series A Preferred Stock [Member]
Liabilities
Series A preferred units (30 million and 30 million units issued and outstanding)	$ 965	$ 965

XML

Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Jun. 30, 2022	Dec. 31, 2021
Limited Partners Common Units [Member] | Public [Member]
Units issued	365.0	369.0
Units Outstanding	365.0	369.0
Limited Partners Common Units [Member] | Marathon Petroleum Corporation [Member]
Units issued	647.0	647.0
Units Outstanding	647.0	647.0
Series B Preferred Stock [Member]
Preferred Units, Issued	0.6	0.6
Preferred Units, Outstanding	0.6	0.6
Series A Convertible Preferred Units
Preferred Units, Issued	30.0	30.0
Preferred Units, Outstanding	30.0	30.0

XML

Consolidated Statements of Cash Flows - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021
Operating activities:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 1,717	$ 1,463
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs		36	35
Cost, Depreciation and Amortization	[1]	623	647
Goodwill and Intangible Asset Impairment		0	42
Deferred income taxes		4	(1)
Loss on disposal of assets		16	1
Income from equity method investments		(210)	(136)
Proceeds from Equity Method Investment, Distribution		258	239
Increase (Decrease) in Derivative Assets and Liabilities		(16)	39
Changes in:
Current receivables		(131)	(83)
Inventories		(15)	(8)
Current accounts payable and accrued liabilities		253	77
Current assets/current liabilities - related parties		0	101
Increase (Decrease) in Other Operating Assets and Liabilities, Net		0	1
Deferred revenue		41	43
All other, net		36	29
Net cash provided by operating activities		2,612	2,489
Net Cash Provided by (Used in) Investing Activities [Abstract]
Additions to property, plant and equipment		(294)	(235)
Payments to Acquire Businesses, Net of Cash Acquired		(28)	0
Disposal of assets		67	74
Payments to Acquire Equity Method Investments		(156)	(84)
Net cash used in investing activities		(411)	(245)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Long-term debt - borrowings		2,385	2,800
Long-term debt - repayments		(1,201)	(3,746)
Payments of Debt Issuance Costs		16	0
Payments for Repurchase of Common Stock		(135)	(310)
Distributions to noncontrolling interests		(19)	(20)
Distributions to unitholders and general partner		(1,430)	(1,421)
Proceeds from Contributions from Parent		17	17
All other, net		(4)	(2)
Net cash used in financing activities		(1,916)	(2,251)
Net increase/ (decrease) in cash, cash equivalents and restricted cash		285	(7)
Cash, cash equivalents and restricted cash at beginning of period		13	15
Cash, cash equivalents and restricted cash at end of period		298	8
Related Party Revolving Credit Agreement [Member] | MPC Investment [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Related party debt - borrowings		2,824	4,435
Repayments of Related Party Debt		(4,274)	(3,942)
Series A Preferred Stock [Member] | Preferred Partner [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Distributions to preferred unitholders		(42)	(41)
Series B Preferred Stock [Member] | Preferred Partner [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Distributions to preferred unitholders		$ (21)	$ (21)

[1] Depreciation and amortization attributable to L&S was $129 million and $259 million for the three and six months ended June 30, 2022, respectively, and $136 million and $283 million for the three and six months ended June 30, 2021, respectively. Depreciation and amortization attributable to G&P was $181 million and $364 million for the three and six months ended June 30, 2022, respectively, and $182 million and $364 million for the three and six months ended June 30, 2021, respectively.

XML

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Series B Preferred Stock [Member]	Series A Preferred Stock [Member]	Public [Member] Limited Partners Common Units [Member]	Marathon Petroleum Corporation [Member] Limited Partners Common Units [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]
Preferred Units, Preferred Partners' Capital Accounts		$ 611
Limited Partners' Capital Account				$ 9,384	$ 2,792
Noncontrolling interests	$ 245
Accumulated other comprehensive loss	(15)
Series A preferred units (30 million and 30 million units issued and outstanding)			$ 968
Beginning Balance at Dec. 31, 2020	13,017
Stock Repurchased and Retired During Period, Value	(155)	0	0	(155)	0	$ 0	$ 0
Distributions to:	729	11		266	443	0	9
Temporary Equity, Dividends, Adjustment			20
Partners' Capital Account, Distributions	(745)	(21)		(269)	(445)	0	(10)
Other	(3)	0		0	(1)	(2)	0
Ending Balance at Mar. 31, 2021	12,850
Temporary Equity, Net Income			20
Partners' Capital Account, Contributions	7	0	0	0	7	0	0
Temporary Equity, Other Changes			0
Preferred Units, Preferred Partners' Capital Accounts		601
Limited Partners' Capital Account				9,226	2,796
Noncontrolling interests	244
Accumulated other comprehensive loss	(17)
Series A preferred units (30 million and 30 million units issued and outstanding)			968
Stock Repurchased and Retired During Period, Value	(155)	0	0	(155)	0	0	0
Distributions to:	693	10		251	423	0	9
Temporary Equity, Dividends, Adjustment			21
Partners' Capital Account, Distributions	(717)	0		(262)	(445)	0	(10)
Other	2	0		1	1	0	0
Ending Balance at Jun. 30, 2021	12,795
Temporary Equity, Net Income			21
Partners' Capital Account, Contributions	122	0	0	0	122	0	0
Temporary Equity, Other Changes			0
Preferred Units, Preferred Partners' Capital Accounts		611
Limited Partners' Capital Account				9,061	2,897
Noncontrolling interests	243
Accumulated other comprehensive loss	(17)
Series A preferred units (30 million and 30 million units issued and outstanding)			968
Preferred Units, Preferred Partners' Capital Accounts		611
Limited Partners' Capital Account				8,579	2,638
Noncontrolling interests	241
Accumulated other comprehensive loss	(17)
Series A preferred units (30 million and 30 million units issued and outstanding)			965
Beginning Balance at Dec. 31, 2021	12,052
Stock Repurchased and Retired During Period, Value	(100)	0	0	(100)	0	0	0
Distributions to:	812	11		287	506	0	8
Temporary Equity, Dividends, Adjustment			21
Partners' Capital Account, Distributions	(746)	(21)		(260)	(456)	0	(9)
Other	8	0		(1)	0	9	0
Ending Balance at Mar. 31, 2022	12,036
Temporary Equity, Net Income			21
Partners' Capital Account, Contributions	10	0	0	0	10	0	0
Temporary Equity, Other Changes			0
Preferred Units, Preferred Partners' Capital Accounts		601
Limited Partners' Capital Account				8,505	2,698
Noncontrolling interests	240
Accumulated other comprehensive loss	(8)
Series A preferred units (30 million and 30 million units issued and outstanding)			965
Stock Repurchased and Retired During Period, Value	(35)	0	0	(35)	0	0	0
Distributions to:	863	10		304	540	0	9
Temporary Equity, Dividends, Adjustment			21
Partners' Capital Account, Distributions	(724)	0		(257)	(457)	0	(10)
Other	2	0		1	1	0	0
Ending Balance at Jun. 30, 2022	12,144
Temporary Equity, Net Income			21
Partners' Capital Account, Contributions	2	0	0	0	2	$ 0	$ 0
Temporary Equity, Other Changes			0
Preferred Units, Preferred Partners' Capital Accounts		$ 611
Limited Partners' Capital Account				$ 8,518	$ 2,784
Noncontrolling interests	239
Accumulated other comprehensive loss	$ (8)
Series A preferred units (30 million and 30 million units issued and outstanding)			$ 965

XML

Description of the Business and Basis of Presentation

6 Months Ended

Jun. 30, 2022

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 gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the 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, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

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 information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2021. The results of operations for the three and six months ended June 30, 2022 are not necessarily indicative of the results to be expected for the full year.

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.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

XML

Accounting Standards Accounting Standards

6 Months Ended

Jun. 30, 2022

Accounting Changes and Error Corrections [Abstract]

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

Accounting Standards

Recently Adopted

ASU 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance

In November 2021, the FASB issued guidance requiring disclosures for certain types of government assistance that have been accounted for by analogy to grant or contribution models. Disclosures will include information about the type of transactions, accounting and the impact on financial statements. MPLX prospectively adopted this standard in the first quarter of 2022. The adoption of this standard did not have a material impact on our financial statements or disclosures.

XML

Investments and Noncontrolling Interest

6 Months Ended

Jun. 30, 2022

Equity Method Investments and Joint Ventures [Abstract]

Investments and Noncontrolling Interests [Text Block]

Investments and Noncontrolling Interests

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

	Ownership as of	Carrying value at
	June 30,	June 30,		December 31,
(In millions, except ownership percentages)	2022	2022		2021
L&S
MarEn Bakken Company LLC(1)	25%	$	493	$	449
Illinois Extension Pipeline Company, L.L.C.	35%	244		243
LOOP LLC	41%	278		265
Andeavor Logistics Rio Pipeline LLC(2)	67%	180		183
Minnesota Pipe Line Company, LLC	17%	182		183
Whistler Pipeline LLC(2)	38%	174		155
Explorer Pipeline Company	25%	59		66
W2W Holdings LLC(2)	50%	59		58
Other(2)		136		116
Total L&S		1,805		1,718
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	683		680
Sherwood Midstream LLC(2)	50%	535		544
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	339		332
MarkWest Torñado GP, L.L.C.(2)	60%	286		246
Rendezvous Gas Services, L.L.C.(2)	78%	143		147
Sherwood Midstream Holdings LLC(2)	51%	130		136
Centrahoma Processing LLC	40%	134		133
Other(2)		44		45
Total G&P		2,294		2,263
Total		$	4,099	$	3,981

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

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

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

Sherwood Midstream LLC (“Sherwood Midstream”) has been deemed the primary beneficiary of Sherwood Midstream Holdings LLC (“Sherwood Midstream Holdings”) due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. Therefore, MPLX also reports its portion of Sherwood Midstream Holdings’ net assets as a component of its investment in Sherwood Midstream. As of June 30, 2022, MPLX has a 24.55 percent indirect ownership interest in Sherwood Midstream Holdings through Sherwood Midstream.

MPLX’s maximum exposure to loss as a result of its involvement with equity method investments includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. MPLX did not provide any financial support to equity method investments that it was not contractually obligated to provide during the six months ended June 30, 2022.

Summarized financial information for MPLX’s equity method investments for the six months ended June 30, 2022 and 2021 is as follows:

	Six Months Ended June 30, 2022
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	550	$	637	$	1,187
Costs and expenses	299		279		578
Income from operations	251		358		609
Net income	227		328		555
Income from equity method investments	$	124	$	86	$	210

	Six Months Ended June 30, 2021
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	336	$	607	$	943
Costs and expenses	217		284		501
Income from operations	119		323		442
Net income	105		283		388
Income from equity method investments	$	73	$	63	$	136

Summarized balance sheet information for MPLX’s equity method investments as of June 30, 2022 and December 31, 2021 is as follows:

	June 30, 2022
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	363	$	394	$	757
Noncurrent assets	7,583		5,062		12,645
Current liabilities	292		249		541
Noncurrent liabilities	$	2,464	$	805	$	3,269

	December 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	335	$	411	$	746
Noncurrent assets	7,439		4,895		12,334
Current liabilities	217		310		527
Noncurrent liabilities	$	2,461	$	788	$	3,249

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Related Party Agreements and Transactions

6 Months Ended

Jun. 30, 2022

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, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products, 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 agreements.

On June 30, 2022, MPLX and MPC entered into a Master Amendment to Transportation Services Agreements (“Master Amendment”). The Master Amendment extends the term of six transportation services agreements through 2032 and provides

for automatic renewals of up to two additional five-year terms, subject to either party providing written notice at least six months prior to the end of the then-current term.

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 extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC Investment. The borrowing capacity of the MPC Loan Agreement is $1.5 billion aggregate principal amount of all loans outstanding at any one time. The loan agreement is scheduled to expire, and borrowings under the loan agreement are scheduled to mature and 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 maturity. Borrowings under the MPC Loan Agreement bear interest at LIBOR plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 11.

Activity on the MPC Loan Agreement was as follows:

	Six Months Ended June 30,
(In millions)	2022			2021
Borrowings	$	2,824		$	4,435
Average interest rate of borrowings	1.458		%	1.354		%
Repayments	$	4,274		$	3,942
Outstanding balance at end of period	$	—		$	493

Related Party Revenue

Related party sales to MPC primarily consist of crude oil and refined products pipeline and trucking transportation services based on tariff or 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. These agreements are classified as Other income - related parties on the Consolidated Statements of Income.

Certain product sales to MPC net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three and six months ended June 30, 2022, these sales totaled $281 million and $574 million, respectively. For the three and six months ended June 30, 2021, these sales totaled $177 million and $345 million, respectively.

Related Party Expenses

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

For the three and six months ended June 30, 2022, General and administrative expenses incurred from MPC totaled $58 million and $113 million, respectively. For the three and six months ended June 30, 2021, General and administrative expenses incurred from MPC totaled $63 million and $120 million, respectively.

Some charges incurred under the omnibus and ESA agreements are related to engineering services and are associated with assets under construction. These charges are added to Property, plant and equipment, net on the Consolidated Balance Sheets. For the three and six months ended June 30, 2022, these charges totaled $19 million and $38 million, respectively. For the three and six months ended June 30, 2021, these charges totaled $15 million and $27 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 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 received under these agreements (excluding payments received under agreements classified as sales-type leases) 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. Deficiency payments under agreements that have been classified as sales-type leases are recorded as a reduction against the corresponding lease receivable. In addition, capital projects MPLX undertakes at the request of MPC are reimbursed in cash and recognized as revenue over the remaining term of the applicable agreements or in some cases, as a contribution from MPC.

(In millions)	June 30, 2022		December 31, 2021
Current assets - related parties
Receivables	$	628	$	555
Prepaid	10		4
Other	2		3
Lease receivables	91		82
Total	731		644
Noncurrent assets - related parties
Long-term receivables	27		31
Right of use assets	229		229
Long-term lease receivables	822		854
Unguaranteed residual asset	64		47
Total	1,142		1,161
Current liabilities - related parties
MPC loan agreement and other payables(1)	329		1,702
Operating lease liabilities	1		1
Deferred revenue - Minimum volume deficiencies	32		35
Deferred revenue - Project reimbursements	41		42
Total	403		1,780
Long-term liabilities - related parties
Long-term operating lease liabilities	228		228
Long-term deferred revenue - Project reimbursements	75		74
Total	$	303	$	302

(1)    Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in Current liabilities - related parties on the Consolidated Balance Sheets. There were no borrowings outstanding on the intercompany loan with MPC as of June 30, 2022.

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Equity

6 Months Ended

Jun. 30, 2022

Equity [Abstract]

Equity

Equity

The changes in the number of common units during the six months ended June 30, 2022 are summarized below:

(In units)	Common Units
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	183,478
Units redeemed in unit repurchase program	(4,156,956)
Balance at June 30, 2022	1,012,204,900

Unit Repurchase Program

On November 2, 2020, MPLX announced the board authorization of a unit repurchase program for the repurchase of up to $1 billion of MPLX’s outstanding common units held by the public.

Total unit repurchases were as follows for the respective periods:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions, except per unit data)	2022		2021		2022		2021
Number of common units repurchased	1		6		4		12
Cash paid for common units repurchased	$	35	$	155	$	135	$	310
Average cost per unit	$	33.74	$	27.40	$	32.48	$	26.02

As of June 30, 2022, we had $202 million remaining under the existing unit repurchase authorization. On August 2, 2022, MPLX announced the board of directors approved an incremental $1 billion unit repurchase authorization. The unit repurchase authorizations have no expiration date. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, accelerated unit repurchases, tender offers or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing of repurchases will depend upon several factors, including market and business conditions, and repurchases may be discontinued at any time.

Series B Preferred Units

MPLX has 600,000 outstanding units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of MPLX with a price to the public of $1,000 per unit (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. Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, 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, in each case assuming a distribution is declared by the Board of Directors. MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023 at the Series B preferred unit redemption price of $1,000 per unit, plus any accumulated and unpaid distributions up to the redemption date.

Cash distributions

On July 26, 2022, MPLX declared a cash distribution for the second quarter of 2022, totaling $714 million, or $0.7050 per common unit. This distribution will be paid on August 12, 2022 to common unitholders of record on August 5, 2022. This rate will also be received by Series A preferred unitholders.

Quarterly distributions for 2022 and 2021 are summarized below:

(Per common unit)	2022		2021
March 31,	$	0.7050	$	0.6875
June 30,	0.7050		0.6875

In accordance with the distribution rights discussed above, MPLX will make a cash distribution totaling $21 million to Series B unitholders on August 15, 2022.

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and six months ended June 30, 2022 and 2021. Distributions, although earned, are not accrued until declared. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the

distributions were earned.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	714	$	705	$	1,427	$	1,412
Series A preferred unit distributions	21		21		42		41
Series B preferred unit distributions	10		10		21		21
Total cash distributions declared	$	745	$	736	$	1,490	$	1,474

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Net Income Per Limited Partner Unit

6 Months Ended

Jun. 30, 2022

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Net Income Per Limited Partner Unit

Net income per unit applicable to common units is computed by dividing net income attributable to MPLX LP less income allocated to participating securities by the weighted average number of common units outstanding.

During the three and six months ended June 30, 2022 and 2021, MPLX had participating securities consisting of common units, certain equity-based compensation awards, Series A preferred units and Series B preferred units and had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three and six months ended June 30, 2022 and 2021 were less than 1 million.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Net income attributable to MPLX LP	$	875	$	706	$	1,700	$	1,445
Less: Distributions declared on Series A preferred units	21		21		42		41
Distributions declared on Series B preferred units	10		10		21		21
Limited partners’ distributions declared on MPLX common units (including common units of general partner)	714		705		1,427		1,412
Undistributed net gain/ (loss) attributable to MPLX LP	$	130	$	(30)	$	210	$	(29)

	Three Months Ended June 30, 2022
(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	$	714	$	21	$	10	$	745
Undistributed net gain attributable to MPLX LP	126		$	4	—		130
Net income attributable to MPLX LP(1)	$	840	$	25	$	10	$	875
Weighted average units outstanding:
Basic	1,012
Diluted	1,012
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.83
Diluted	$	0.83

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

	Three Months Ended June 30, 2021
(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	$	705	$	21	$	10	$	736
Undistributed net loss attributable to MPLX LP	(30)		—		—		(30)
Net income attributable to MPLX LP(1)	$	675	$	21	$	10	$	706
Weighted average units outstanding:
Basic	1,029
Diluted	1,029
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.66
Diluted	$	0.66

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

	Six Months Ended June 30, 2022
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,427	$	42	$	21	$	1,490
Undistributed net gain attributable to MPLX LP	204		6		—		210
Net income attributable to MPLX LP(1)	$	1,631	$	48	$	21	$	1,700
Weighted average units outstanding:
Basic	1,013
Diluted	1,014
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.61
Diluted	$	1.61

(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.

	Six Months Ended June 30, 2021
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,412	$	41	$	21	$	1,474
Undistributed net loss attributable to MPLX LP	(29)		—		—		(29)
Net income attributable to MPLX LP(1)	$	1,383	$	41	$	21	$	1,445
Weighted average units outstanding:
Basic	1,033
Diluted	1,033
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.34
Diluted	$	1.34

(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.

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Segment Information

6 Months Ended

Jun. 30, 2022

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 – gathers, transports, stores and distributes crude oil, refined products, and other hydrocarbon-based products. Also includes the operation of refining logistics, fuels distribution and inland marine businesses, terminals, rail facilities, and storage caverns.

•G&P – gathers, processes and transports natural gas; and 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) interest and other financial costs; (iii) impairment expense; (iv) income/(loss) from equity method investments; (v) distributions and adjustments related to equity method investments; (vi) noncontrolling interests; and (vii) 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. Assets by segment are not a measure used to assess the performance of the Partnership by our CEO and thus are not reported in our disclosures.

The tables below present information about revenues and other income, Segment Adjusted EBITDA, capital expenditures and investments in unconsolidated affiliates for our reportable segments:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
L&S
Service revenue	$	1,010	$	992	$	1,993	$	1,945
Rental income	208		176		383		425
Product related revenue	7		4		11		8
Sales-type lease revenue	114		136		225		173
Income from equity method investments	59		35		111		71
Other income	22		16		34		31
Total segment revenues and other income(1)	1,420		1,359		2,757		2,653
Segment Adjusted EBITDA(2)	966		947		1,870		1,843
Capital expenditures	81		76		158		135
Investments in unconsolidated affiliates	10		13		78		22
G&P
Service revenue	505		493		991		1,001
Rental income	92		91		173		183
Product related revenue	860		407		1,521		804
Income from equity method investments	52		31		99		65
Other income	11		14		9		28
Total segment revenues and other income(1)	1,520		1,036		2,793		2,081
Segment Adjusted EBITDA(2)	491		427		980		883
Capital expenditures	95		36		190		66
Investments in unconsolidated affiliates	$	36	$	36	$	78	$	62

(1)    Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $293 million for the three and six months ended June 30, 2022, respectively, and $138 million and $267 million for the three and six months ended June 30, 2021, respectively. Third party revenues for the G&P segment were $1,454 million and $2,666 million for the three and six months ended June 30, 2022, respectively, and $988 million and $1,977 million for the three and six months ended June 30, 2021, respectively.

(2)    See below for the reconciliation from Segment Adjusted EBITDA to Net income.

The table below provides a reconciliation between Net income and Segment Adjusted EBITDA.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Reconciliation to Net income:
L&S Segment Adjusted EBITDA	$	966	$	947	$	1,870	$	1,843
G&P Segment Adjusted EBITDA	491		427		980		883
Total reportable segments	1,457		1,374		2,850		2,726
Depreciation and amortization(1)	(310)		(318)		(623)		(647)
Impairment expense	—		(42)		—		(42)
Interest and other financial costs	(233)		(216)		(455)		(441)
Income from equity method investments	111		66		210		136
Distributions/adjustments related to equity method investments	(152)		(121)		(284)		(242)
Other	1		(38)		—		(47)
Adjusted EBITDA attributable to noncontrolling interests	10		10		19		20
Net income	$	884	$	715	$	1,717	$	1,463

(1)    Depreciation and amortization attributable to L&S was $129 million and $259 million for the three and six months ended June 30, 2022, respectively, and $136 million and $283 million for the three and six months ended June 30, 2021, respectively. Depreciation and

amortization attributable to G&P was $181 million and $364 million for the three and six months ended June 30, 2022, respectively, and $182 million and $364 million for the three and six months ended June 30, 2021, respectively.

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Property, Plant and Equipment

6 Months Ended

Jun. 30, 2022

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

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

	June 30, 2022						December 31, 2021
(In millions)	Gross PP&E		Accumulated Depreciation		Net PP&E		Gross PP&E		Accumulated Depreciation(1)		Net PP&E
L&S	$	12,442	$	3,424	$	9,018	$	12,371	$	3,227	$	9,144
G&P	14,312		3,563		10,749		14,175		3,277		10,898
Total	$	26,754	$	6,987	$	19,767	$	26,546	$	6,504	$	20,042

(1)    Includes property, plant and equipment impairment charges recorded in the second quarter of 2021, 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.

In the second quarter of 2021, we recognized impairment expense of $42 million within our G&P segment related to our continued emphasis on portfolio optimization with the divestiture of several non-core assets and the closure of other non-core assets.

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Fair Value Measurements

6 Months Ended

Jun. 30, 2022

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 10.

Level 3 instruments relate to an embedded derivative liability for 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 $0.72 to $1.98 per gallon with a weighted average of $0.98 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal 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. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of June 30, 2022 or December 31, 2021.

Changes in Level 3 Fair Value Measurements

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

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Embedded derivatives in commodity contracts (net):
Fair value at beginning of period	$	(99)	$	(66)	$	(108)	$	(63)
Total gain/ (loss) (realized and unrealized) included in earnings(1)	4		(39)		8		(45)
Settlements	3		3		8		6
Fair value at end of period	(92)		(102)		(92)		(102)
The amount of total gain/ (loss) for the period included in earnings attributable to the change in unrealized gain/ (loss) relating to liabilities still held at end of period	$	3	$	(39)	$	8	$	(41)

(1)     Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs 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 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 10).

The fair value of MPLX’s debt is estimated based on recent market non-binding indicative quotes. The debt fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs:

	June 30, 2022				December 31, 2021
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Outstanding debt(1)	$	18,604	$	19,881	$	20,779	$	18,664

(1)    Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring

Level 3 instruments relate to an embedded derivative liability for 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 $0.72 to $1.98 per gallon with a weighted average of $0.98 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal 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. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of June 30, 2022 or December 31, 2021.

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Derivative Financial Instruments

6 Months Ended

Jun. 30, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities Disclosure [Text Block]

Derivative Financial Instruments

As of June 30, 2022, MPLX had no 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 2027. The customer has the unilateral option to extend the agreement for one five-year term through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending option have been aggregated into a single compound embedded derivative. The probability of the customer exercising its option 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. For further information regarding the fair value measurement of derivative instruments, see Note 9. As of June 30, 2022 and December 31, 2021, the estimated fair value of this contract was a liability of $92 million and $108 million, respectively.

Certain derivative positions are subject to master netting agreements, therefore, MPLX has elected to offset derivative assets and liabilities that are legally permissible to be offset. As of June 30, 2022 and December 31, 2021, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	June 30, 2022				December 31, 2021
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability		Asset		Liability
Commodity contracts
Other current assets / Other current liabilities	$	—	$	(14)	$	—	$	(15)
Other noncurrent assets / Other long-term liabilities	—		(78)		—		(93)
Total	$	—	$	(92)	$	—	$	(108)

We make a distinction between realized or 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. The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Purchased product costs
Realized loss	$	(3)	$	(3)	$	(8)	$	(6)
Unrealized gain/ (loss)	7		(36)		16		(39)
Purchased product cost derivative gain/ (loss)	$	4	$	(39)	$	8	$	(45)

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Debt

6 Months Ended

Jun. 30, 2022

Debt Disclosure [Abstract]

Debt

Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	June 30, 2022		December 31, 2021
MPLX LP:
MPLX Credit Agreement	$	—	$	300
Fixed rate senior notes	20,032		18,532
Consolidated subsidiaries:
MarkWest	23		23
ANDX	45		45
Financing lease obligations	8		9
Total	20,108		18,909
Unamortized debt issuance costs	(114)		(102)
Unamortized discount	(219)		(236)
Amounts due within one year	(1,000)		(499)
Total long-term debt due after one year	$	18,775	$	18,072

Credit Agreement

On July 7, 2022, MPLX entered into a new five-year credit agreement (the “New MPLX Credit Agreement”) to replace the previous $3.5 billion credit facility that was scheduled to expire July 2024. The New MPLX Credit Agreement, among other things, provides for a $2 billion unsecured revolving credit facility that matures in July 2027. The New MPLX Credit Agreement provides for letter of credit issuing capacity under the facility of $150 million. Letter of credit issuing capacity is included in, not in addition to, the $2 billion borrowing capacity of the New MPLX Credit Agreement. The financial covenants of the New MPLX Credit Agreement are substantially the same as those contained in the previous credit agreement. Borrowings under the New MPLX Credit Agreement bear interest, at MPLX’s election, at either the Adjusted Term SOFR or the Alternate Base Rate, both as defined in the New MPLX Credit Agreement, plus an applicable margin.

During the six months ended June 30, 2022, MPLX borrowed $900 million under the MPLX Credit Agreement, at an average interest rate of 1.454 percent, and repaid $1,200 million. At June 30, 2022, MPLX had no outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of approximately $3.5 billion.

Fixed Rate Senior Notes

MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes maturing between 2022 and 2058 with interest rates ranging from 1.750 percent to 5.500 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.

On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The 2052 Senior Notes were offered at a price to the public of 98.982 percent with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the intercompany loan agreement with MPC and the MPLX revolving credit facility.

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Revenue

6 Months Ended

Jun. 30, 2022

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer [Text Block]

Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three and six months ended June 30, 2022 and 2021:

	Three Months Ended June 30, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	77	$	500	$	577
Service revenue - related parties	933		5		938
Service revenue - product related	—		118		118
Product sales	2		696		698
Product sales - related parties	5		46		51
Total revenues from contracts with customers	$	1,017	$	1,365	2,382
Non-ASC 606 revenue(1)					558
Total revenues and other income					$	2,940

	Three Months Ended June 30, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	91	$	487	$	578
Service revenue - related parties	901		6		907
Service revenue - product related	—		76		76
Product sales	1		303		304
Product sales - related parties	3		28		31
Total revenues from contracts with customers	$	996	$	900	1,896
Non-ASC 606 revenue(1)					499
Total revenues and other income					$	2,395

	Six Months Ended June 30, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	149	$	982	$	1,131
Service revenue - related parties	1,844		9		1,853
Service revenue - product related	—		241		241
Product sales	3		1,192		1,195
Product sales - related parties	8		88		96
Total revenues from contracts with customers	$	2,004	$	2,512	4,516
Non-ASC 606 revenue(1)					1,034
Total revenues and other income					$	5,550

	Six Months Ended June 30, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	175	$	992	$	1,167
Service revenue - related parties	1,770		9		1,779
Service revenue - product related	—		153		153
Product sales	2		584		586
Product sales - related parties	6		67		73
Total revenues from contracts with customers	$	1,953	$	1,805	3,758
Non-ASC 606 revenue(1)					976
Total revenues and other income					$	4,734

(1)    Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

Contract Balances

Contract assets typically relate to deficiency payments related to minimum volume commitments and aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer. Contract assets are included in Other current assets and Other noncurrent 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. The sales and related Receivables, net 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 ASC 606 contract balances of each respective line, for the six-month periods ended June 30, 2022 and 2021:

(In millions)	Balance at December 31, 2021		Additions/ (Deletions)		Revenue Recognized(1)		Balance at June 30, 2022
Contract assets	$	25	$	(14)	$	—	$	11
Long-term contract assets	2		—		—		2
Deferred revenue	56		26		(25)		57
Deferred revenue - related parties	60		54		(57)		57
Long-term deferred revenue	135		17		—		152
Long-term deferred revenue - related parties	31		(3)		—		28
Long-term contract liabilities	$	5	$	—	$	—	$	5

(In millions)	Balance at December 31, 2020		Additions/ (Deletions)		Revenue Recognized(1)		Balance at June 30, 2021
Contract assets	$	40	$	(25)	$	1	$	16
Long-term contract assets	2		—		—		2
Deferred revenue	37		24		(17)		44
Deferred revenue - related parties	91		37		(50)		78
Long-term deferred revenue	119		9		—		128
Long-term deferred revenue - related parties	48		(8)		—		40
Long-term contract liabilities	$	6	$	—	$	—	$	6

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

Remaining Performance Obligations

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

As of June 30, 2022, unsatisfied performance obligations included on the Consolidated Balance Sheets are $293 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 22 years. A portion of this amount is not disclosed in the table below as it is deemed variable consideration due to volume variability.

(In millions)
2022	$	943
2023	1,727
2024	1,601
2025	1,530
2026	1,373
2027 and thereafter	1,865
Total revenue on remaining performance obligations(1)(2)(3)	$	9,039

(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 and sales-type leases are excluded from this table.

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

We do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less.

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Supplemental Cash Flow Information

6 Months Ended

Jun. 30, 2022

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information [Text Block]

Supplemental Cash Flow Information

	Six Months Ended June 30,
(In millions)	2022		2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	393	$	414
Income taxes paid	$	1	$	1

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

	Six Months Ended June 30,
(In millions)	2022		2021
Increase/ (decrease) in capital accruals	$	54	$	(34)

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Leases, Codification Topic 842

6 Months Ended

Jun. 30, 2022

Leases [Abstract]

Leases of Lessor Disclosure [Text Block]

Leases

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

	Three Months Ended  June 30, 2022				Three Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	198	$	102	$	168	$	99
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	112		—		135		—
Interest income (Revenue from variable lease payments)	2		—		1		—
Sales-type lease revenue	$	114	$	—	$	136	$	—

	Six Months Ended  June 30, 2022				Six Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	363	$	193	$	410	$	198
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	222		—		172		—
Interest income (Revenue from variable lease payments)	3		—		1		—
Sales-type lease revenue	$	225	$	—	$	173	$	—

See Note 4 for additional information on where related party lease assets are recorded in the Consolidated Balance Sheets. Capital expenditures related to assets subject to sales-type lease arrangements were $18 million for the six months ended June 30, 2022, these amounts are reflected as Additions to property, plant and equipment on the Consolidated Statements of Cash Flows. As of June 30, 2022 and December 31, 2021, third party lease assets are less than $1 million and are included within the Receivables, net and Other noncurrent assets captions within the Consolidated Balance Sheets.

During the second quarter of 2021, reimbursements for projects and changes to minimum volume commitments at certain L&S locations were agreed to between MPLX and MPC. These reimbursements and minimum volume commitments relate to the storage, transportation and terminal services agreements between MPLX and MPC at these locations and required the embedded leases within these agreements to be reassessed under ASC 842. As a result of the reassessment, certain leases were reclassified from an operating lease to a sales-type lease. Accordingly, the underlying assets previously shown on the Consolidated Balance Sheets associated with the sales-type leases 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 during the respective periods. See Note 4 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 the impacted storage and terminal services agreements are related to a common control transaction. During the second quarter of 2021, MPLX derecognized approximately $421 million of property, plant and equipment, recorded a lease receivable of approximately $519 million, recorded an unguaranteed residual asset of approximately $14 million with the difference recorded as a deemed Contribution from MPC of $112 million.

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Commitments and Contingencies

6 Months Ended

Jun. 30, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]

Commitments and ContingenciesMPLX 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 a liability, MPLX is unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material.

Environmental Matters

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

At June 30, 2022 and December 31, 2021, accrued liabilities for remediation totaled $27 million and $23 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, that may be imposed.

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.

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.

We hold a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. Completion of the EIS may now be delayed as the Army Corps engages with the Standing Rock Sioux Tribe on the tribe’s reasons for withdrawing as a cooperating agency with respect to preparation of the EIS.

In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.

We have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, has 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. If the pipeline were temporarily shut down, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of June 30, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.

Other Legal Proceedings

In July 2020, Tesoro High Plains Pipeline Company, LLC (“THPP”), a subsidiary of MPLX, received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification demanded the immediate cessation of pipeline operations and assessed trespass damages of approximately $187 million. On appeal, the Assistant Secretary - Indian Affairs issued an order vacating the BIA’s trespass order and remanded to the Regional Director for the BIA Great Plains Region to issue a new decision based on specific criteria. On December 15, 2020, the Regional Director of the BIA issued a new trespass notice to THPP, finding that THPP was in trespass and assessing trespass damages of approximately $4 million (including interest), which has been paid. The order also required that THPP immediately cease and desist use of the portion of the pipeline that crosses the property at issue. THPP has complied with the Regional Director’s December 15, 2020 notice. In March 2021, THPP received a copy of an order purporting to vacate all orders related to THPP’s alleged trespass issued by the BIA between July 2, 2020 and January 14, 2021. The order directs the Regional Director of the BIA to reconsider the issue of THPP’s alleged trespass and issue a new

order, if necessary, after all interested parties have had an opportunity to be heard. Subsequently, landowners voluntarily dismissed the suit filed in the District of North Dakota. On April 23, 2021, THPP filed a lawsuit in the District of North Dakota against the United States of America, the U.S. Department of the Interior and the BIA (together, the “U.S. Government Parties”) challenging the March order purporting to vacate all previous orders related to THPP’s alleged trespass.

On February 8, 2022, the U.S. Government Parties filed their answer to THPP’s suit, asserting counterclaims for trespass and ejectment. The U.S. Government Parties claim THPP is in continued trespass with respect to the pipeline and seek disgorgement of pipeline profits from June 1, 2013 to present, removal of the pipeline and remediation. We intend to vigorously defend ourselves against these counterclaims. We continue to work towards a settlement of this matter with holders of the property rights at issue.

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 other lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated financial position, results of operations or cash flows.

Contractual Commitments and Contingencies

From time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of June 30, 2022, management does not believe there are any indications that MPLX will not be able to meet the construction milestones, that force majeure does not apply or that such fees and charges will otherwise be triggered.

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

6 Months Ended

Jun. 30, 2022

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 gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the 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, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

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 information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2021. The results of operations for the three and six months ended June 30, 2022 are not necessarily indicative of the results to be expected for the full year.

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.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block]

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.Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

Nature of Operations

We are engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the 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, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

Basis of Accounting, Policy

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 information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

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Net Income Per Limited Partner Unit Accounting Policy (Policies)	6 Months Ended
	Jun. 30, 2022
Accounting Policies [Abstract]
Earnings Per Share, Policy [Policy Text Block]	Net income per unit applicable to common units is computed by dividing net income attributable to MPLX LP less income allocated to participating securities by the weighted average number of common units outstanding.

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Investments and Noncontrolling Interests (Tables)

6 Months Ended

Jun. 30, 2022

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments [Table Text Block]

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

	Ownership as of	Carrying value at
	June 30,	June 30,		December 31,
(In millions, except ownership percentages)	2022	2022		2021
L&S
MarEn Bakken Company LLC(1)	25%	$	493	$	449
Illinois Extension Pipeline Company, L.L.C.	35%	244		243
LOOP LLC	41%	278		265
Andeavor Logistics Rio Pipeline LLC(2)	67%	180		183
Minnesota Pipe Line Company, LLC	17%	182		183
Whistler Pipeline LLC(2)	38%	174		155
Explorer Pipeline Company	25%	59		66
W2W Holdings LLC(2)	50%	59		58
Other(2)		136		116
Total L&S		1,805		1,718
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	683		680
Sherwood Midstream LLC(2)	50%	535		544
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	339		332
MarkWest Torñado GP, L.L.C.(2)	60%	286		246
Rendezvous Gas Services, L.L.C.(2)	78%	143		147
Sherwood Midstream Holdings LLC(2)	51%	130		136
Centrahoma Processing LLC	40%	134		133
Other(2)		44		45
Total G&P		2,294		2,263
Total		$	4,099	$	3,981

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

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

Summarized Financial Information For Equity Method Investees Table [Table Text Block]

Summarized financial information for MPLX’s equity method investments for the six months ended June 30, 2022 and 2021 is as follows:

	Six Months Ended June 30, 2022
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	550	$	637	$	1,187
Costs and expenses	299		279		578
Income from operations	251		358		609
Net income	227		328		555
Income from equity method investments	$	124	$	86	$	210

	Six Months Ended June 30, 2021
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	336	$	607	$	943
Costs and expenses	217		284		501
Income from operations	119		323		442
Net income	105		283		388
Income from equity method investments	$	73	$	63	$	136

Summarized balance sheet information for MPLX’s equity method investments as of June 30, 2022 and December 31, 2021 is as follows:

	June 30, 2022
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	363	$	394	$	757
Noncurrent assets	7,583		5,062		12,645
Current liabilities	292		249		541
Noncurrent liabilities	$	2,464	$	805	$	3,269

	December 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	335	$	411	$	746
Noncurrent assets	7,439		4,895		12,334
Current liabilities	217		310		527
Noncurrent liabilities	$	2,461	$	788	$	3,249

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Related Party Agreements and Transactions (Tables)

6 Months Ended

Jun. 30, 2022

Related Party Transactions [Abstract]

Schedule of Short-term Debt

Activity on the MPC Loan Agreement was as follows:

	Six Months Ended June 30,
(In millions)	2022			2021
Borrowings	$	2,824		$	4,435
Average interest rate of borrowings	1.458		%	1.354		%
Repayments	$	4,274		$	3,942
Outstanding balance at end of period	$	—		$	493

Schedule of Related Party Transactions [Table Text Block]

(In millions)	June 30, 2022		December 31, 2021
Current assets - related parties
Receivables	$	628	$	555
Prepaid	10		4
Other	2		3
Lease receivables	91		82
Total	731		644
Noncurrent assets - related parties
Long-term receivables	27		31
Right of use assets	229		229
Long-term lease receivables	822		854
Unguaranteed residual asset	64		47
Total	1,142		1,161
Current liabilities - related parties
MPC loan agreement and other payables(1)	329		1,702
Operating lease liabilities	1		1
Deferred revenue - Minimum volume deficiencies	32		35
Deferred revenue - Project reimbursements	41		42
Total	403		1,780
Long-term liabilities - related parties
Long-term operating lease liabilities	228		228
Long-term deferred revenue - Project reimbursements	75		74
Total	$	303	$	302

(1)    Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in Current liabilities - related parties on the Consolidated Balance Sheets. There were no borrowings outstanding on the intercompany loan with MPC as of June 30, 2022.

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Equity (Tables)

6 Months Ended

Jun. 30, 2022

Equity [Abstract]

Schedule of Stockholders Equity [Table Text Block]

The changes in the number of common units during the six months ended June 30, 2022 are summarized below:

(In units)	Common Units
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	183,478
Units redeemed in unit repurchase program	(4,156,956)
Balance at June 30, 2022	1,012,204,900

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

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and six months ended June 30, 2022 and 2021. Distributions, although earned, are not accrued until declared. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	714	$	705	$	1,427	$	1,412
Series A preferred unit distributions	21		21		42		41
Series B preferred unit distributions	10		10		21		21
Total cash distributions declared	$	745	$	736	$	1,490	$	1,474

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Net Income Per Limited Partner Unit (Tables)

6 Months Ended

Jun. 30, 2022

Earnings Per Share [Abstract]

Schedule of Distributions By Partner By Class [Table Text Block]

During the three and six months ended June 30, 2022 and 2021, MPLX had participating securities consisting of common units, certain equity-based compensation awards, Series A preferred units and Series B preferred units and had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three and six months ended June 30, 2022 and 2021 were less than 1 million.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Net income attributable to MPLX LP	$	875	$	706	$	1,700	$	1,445
Less: Distributions declared on Series A preferred units	21		21		42		41
Distributions declared on Series B preferred units	10		10		21		21
Limited partners’ distributions declared on MPLX common units (including common units of general partner)	714		705		1,427		1,412
Undistributed net gain/ (loss) attributable to MPLX LP	$	130	$	(30)	$	210	$	(29)

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended June 30, 2022
(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	$	714	$	21	$	10	$	745
Undistributed net gain attributable to MPLX LP	126		$	4	—		130
Net income attributable to MPLX LP(1)	$	840	$	25	$	10	$	875
Weighted average units outstanding:
Basic	1,012
Diluted	1,012
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.83
Diluted	$	0.83

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

	Three Months Ended June 30, 2021
(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	$	705	$	21	$	10	$	736
Undistributed net loss attributable to MPLX LP	(30)		—		—		(30)
Net income attributable to MPLX LP(1)	$	675	$	21	$	10	$	706
Weighted average units outstanding:
Basic	1,029
Diluted	1,029
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.66
Diluted	$	0.66

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

	Six Months Ended June 30, 2022
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,427	$	42	$	21	$	1,490
Undistributed net gain attributable to MPLX LP	204		6		—		210
Net income attributable to MPLX LP(1)	$	1,631	$	48	$	21	$	1,700
Weighted average units outstanding:
Basic	1,013
Diluted	1,014
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.61
Diluted	$	1.61

(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.

	Six Months Ended June 30, 2021
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	1,412	$	41	$	21	$	1,474
Undistributed net loss attributable to MPLX LP	(29)		—		—		(29)
Net income attributable to MPLX LP(1)	$	1,383	$	41	$	21	$	1,445
Weighted average units outstanding:
Basic	1,033
Diluted	1,033
Net income attributable to MPLX LP per limited partner unit:
Basic	$	1.34
Diluted	$	1.34

(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.

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Segment Information (Tables)

6 Months Ended

Jun. 30, 2022

Segment Reporting [Abstract]

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

The tables below present information about revenues and other income, Segment Adjusted EBITDA, capital expenditures and investments in unconsolidated affiliates for our reportable segments:

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
L&S
Service revenue	$	1,010	$	992	$	1,993	$	1,945
Rental income	208		176		383		425
Product related revenue	7		4		11		8
Sales-type lease revenue	114		136		225		173
Income from equity method investments	59		35		111		71
Other income	22		16		34		31
Total segment revenues and other income(1)	1,420		1,359		2,757		2,653
Segment Adjusted EBITDA(2)	966		947		1,870		1,843
Capital expenditures	81		76		158		135
Investments in unconsolidated affiliates	10		13		78		22
G&P
Service revenue	505		493		991		1,001
Rental income	92		91		173		183
Product related revenue	860		407		1,521		804
Income from equity method investments	52		31		99		65
Other income	11		14		9		28
Total segment revenues and other income(1)	1,520		1,036		2,793		2,081
Segment Adjusted EBITDA(2)	491		427		980		883
Capital expenditures	95		36		190		66
Investments in unconsolidated affiliates	$	36	$	36	$	78	$	62

(1)    Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $293 million for the three and six months ended June 30, 2022, respectively, and $138 million and $267 million for the three and six months ended June 30, 2021, respectively. Third party revenues for the G&P segment were $1,454 million and $2,666 million for the three and six months ended June 30, 2022, respectively, and $988 million and $1,977 million for the three and six months ended June 30, 2021, respectively.

(2)    See below for the reconciliation from Segment Adjusted EBITDA to Net income.

Reconciliation of Other Significant Reconciling Items from Segments to Consolidated [Table Text Block]

The table below provides a reconciliation between Net income and Segment Adjusted EBITDA.

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Reconciliation to Net income:
L&S Segment Adjusted EBITDA	$	966	$	947	$	1,870	$	1,843
G&P Segment Adjusted EBITDA	491		427		980		883
Total reportable segments	1,457		1,374		2,850		2,726
Depreciation and amortization(1)	(310)		(318)		(623)		(647)
Impairment expense	—		(42)		—		(42)
Interest and other financial costs	(233)		(216)		(455)		(441)
Income from equity method investments	111		66		210		136
Distributions/adjustments related to equity method investments	(152)		(121)		(284)		(242)
Other	1		(38)		—		(47)
Adjusted EBITDA attributable to noncontrolling interests	10		10		19		20
Net income	$	884	$	715	$	1,717	$	1,463

(1)    Depreciation and amortization attributable to L&S was $129 million and $259 million for the three and six months ended June 30, 2022, respectively, and $136 million and $283 million for the three and six months ended June 30, 2021, respectively. Depreciation and

amortization attributable to G&P was $181 million and $364 million for the three and six months ended June 30, 2022, respectively, and $182 million and $364 million for the three and six months ended June 30, 2021, respectively.

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Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2022

Property, Plant and Equipment [Abstract]

Summary of Property, Plant and Equipment

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

	June 30, 2022						December 31, 2021
(In millions)	Gross PP&E		Accumulated Depreciation		Net PP&E		Gross PP&E		Accumulated Depreciation(1)		Net PP&E
L&S	$	12,442	$	3,424	$	9,018	$	12,371	$	3,227	$	9,144
G&P	14,312		3,563		10,749		14,175		3,277		10,898
Total	$	26,754	$	6,987	$	19,767	$	26,546	$	6,504	$	20,042

(1)    Includes property, plant and equipment impairment charges recorded in the second quarter of 2021, as discussed below.

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Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2022

Fair Value Disclosures [Abstract]

Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

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

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Embedded derivatives in commodity contracts (net):
Fair value at beginning of period	$	(99)	$	(66)	$	(108)	$	(63)
Total gain/ (loss) (realized and unrealized) included in earnings(1)	4		(39)		8		(45)
Settlements	3		3		8		6
Fair value at end of period	(92)		(102)		(92)		(102)
The amount of total gain/ (loss) for the period included in earnings attributable to the change in unrealized gain/ (loss) relating to liabilities still held at end of period	$	3	$	(39)	$	8	$	(41)

(1)     Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs 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 our third-party debt, excluding finance leases and unamortized debt issuance costs:

	June 30, 2022				December 31, 2021
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Outstanding debt(1)	$	18,604	$	19,881	$	20,779	$	18,664

(1)    Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

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Derivative Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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

The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	June 30, 2022				December 31, 2021
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability		Asset		Liability
Commodity contracts
Other current assets / Other current liabilities	$	—	$	(14)	$	—	$	(15)
Other noncurrent assets / Other long-term liabilities	—		(78)		—		(93)
Total	$	—	$	(92)	$	—	$	(108)

Derivative Instruments, Gain (Loss) [Table Text Block]

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

	Three Months Ended June 30,				Six Months Ended June 30,
(In millions)	2022		2021		2022		2021
Purchased product costs
Realized loss	$	(3)	$	(3)	$	(8)	$	(6)
Unrealized gain/ (loss)	7		(36)		16		(39)
Purchased product cost derivative gain/ (loss)	$	4	$	(39)	$	8	$	(45)

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Debt (Tables)

6 Months Ended

Jun. 30, 2022

Debt Disclosure [Abstract]

Schedule of Debt [Table Text Block]

MPLX’s outstanding borrowings consist of the following:

(In millions)	June 30, 2022		December 31, 2021
MPLX LP:
MPLX Credit Agreement	$	—	$	300
Fixed rate senior notes	20,032		18,532
Consolidated subsidiaries:
MarkWest	23		23
ANDX	45		45
Financing lease obligations	8		9
Total	20,108		18,909
Unamortized debt issuance costs	(114)		(102)
Unamortized discount	(219)		(236)
Amounts due within one year	(1,000)		(499)
Total long-term debt due after one year	$	18,775	$	18,072

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Revenue (Tables)

6 Months Ended

Jun. 30, 2022

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

The following tables represent a disaggregation of revenue for each reportable segment for the three and six months ended June 30, 2022 and 2021:

	Three Months Ended June 30, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	77	$	500	$	577
Service revenue - related parties	933		5		938
Service revenue - product related	—		118		118
Product sales	2		696		698
Product sales - related parties	5		46		51
Total revenues from contracts with customers	$	1,017	$	1,365	2,382
Non-ASC 606 revenue(1)					558
Total revenues and other income					$	2,940

	Three Months Ended June 30, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	91	$	487	$	578
Service revenue - related parties	901		6		907
Service revenue - product related	—		76		76
Product sales	1		303		304
Product sales - related parties	3		28		31
Total revenues from contracts with customers	$	996	$	900	1,896
Non-ASC 606 revenue(1)					499
Total revenues and other income					$	2,395

	Six Months Ended June 30, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	149	$	982	$	1,131
Service revenue - related parties	1,844		9		1,853
Service revenue - product related	—		241		241
Product sales	3		1,192		1,195
Product sales - related parties	8		88		96
Total revenues from contracts with customers	$	2,004	$	2,512	4,516
Non-ASC 606 revenue(1)					1,034
Total revenues and other income					$	5,550

	Six Months Ended June 30, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	175	$	992	$	1,167
Service revenue - related parties	1,770		9		1,779
Service revenue - product related	—		153		153
Product sales	2		584		586
Product sales - related parties	6		67		73
Total revenues from contracts with customers	$	1,953	$	1,805	3,758
Non-ASC 606 revenue(1)					976
Total revenues and other income					$	4,734

(1)    Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

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

The tables below reflect the changes in ASC 606 contract balances of each respective line, for the six-month periods ended June 30, 2022 and 2021:

(In millions)	Balance at December 31, 2021		Additions/ (Deletions)		Revenue Recognized(1)		Balance at June 30, 2022
Contract assets	$	25	$	(14)	$	—	$	11
Long-term contract assets	2		—		—		2
Deferred revenue	56		26		(25)		57
Deferred revenue - related parties	60		54		(57)		57
Long-term deferred revenue	135		17		—		152
Long-term deferred revenue - related parties	31		(3)		—		28
Long-term contract liabilities	$	5	$	—	$	—	$	5

(In millions)	Balance at December 31, 2020		Additions/ (Deletions)		Revenue Recognized(1)		Balance at June 30, 2021
Contract assets	$	40	$	(25)	$	1	$	16
Long-term contract assets	2		—		—		2
Deferred revenue	37		24		(17)		44
Deferred revenue - related parties	91		37		(50)		78
Long-term deferred revenue	119		9		—		128
Long-term deferred revenue - related parties	48		(8)		—		40
Long-term contract liabilities	$	6	$	—	$	—	$	6

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

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

As of June 30, 2022, unsatisfied performance obligations included on the Consolidated Balance Sheets are $293 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 22 years. A portion of this amount is not disclosed in the table below as it is deemed variable consideration due to volume variability.

(In millions)
2022	$	943
2023	1,727
2024	1,601
2025	1,530
2026	1,373
2027 and thereafter	1,865
Total revenue on remaining performance obligations(1)(2)(3)	$	9,039

(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 and sales-type leases are excluded from this table.

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

We do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less.

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Supplemental Cash Flow Information (Tables)

6 Months Ended

Jun. 30, 2022

Supplemental Cash Flow Elements [Abstract]

Summary of Supplemental Cash Flow Information [Table Text Block]

	Six Months Ended June 30,
(In millions)	2022		2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	393	$	414
Income taxes paid	$	1	$	1

Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures [Table Text Block]

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

	Six Months Ended June 30,
(In millions)	2022		2021
Increase/ (decrease) in capital accruals	$	54	$	(34)

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Leases, Codification Topic 842 (Tables)

6 Months Ended

Jun. 30, 2022

Leases [Abstract]

Sales-type Lease, Lease Income [Table Text Block]

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

	Three Months Ended  June 30, 2022				Three Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	198	$	102	$	168	$	99
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	112		—		135		—
Interest income (Revenue from variable lease payments)	2		—		1		—
Sales-type lease revenue	$	114	$	—	$	136	$	—

	Six Months Ended  June 30, 2022				Six Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	363	$	193	$	410	$	198
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	222		—		172		—
Interest income (Revenue from variable lease payments)	3		—		1		—
Sales-type lease revenue	$	225	$	—	$	173	$	—

Operating Lease, Lease Income [Table Text Block]

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

	Three Months Ended  June 30, 2022				Three Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	198	$	102	$	168	$	99
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	112		—		135		—
Interest income (Revenue from variable lease payments)	2		—		1		—
Sales-type lease revenue	$	114	$	—	$	136	$	—

	Six Months Ended  June 30, 2022				Six Months Ended  June 30, 2021
(In millions)	Related Party		Third Party		Related Party		Third Party
Operating leases:
Rental income	$	363	$	193	$	410	$	198
Sales-type leases:
Interest income (Sales-type rental revenue-fixed minimum)	222		—		172		—
Interest income (Revenue from variable lease payments)	3		—		1		—
Sales-type lease revenue	$	225	$	—	$	173	$	—

XML

Description of Business and Basis of Presentation - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2022
Accounting Policies [Abstract]
Number of reportable segments	2

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Investments and Noncontrolling Interests (Summary of Equity Method Investment Financial Information) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 4,099		$ 4,099		$ 3,981
Revenues		2,940	$ 2,395	5,550	$ 4,734
Costs and Expenses		1,823	1,464	3,373	2,829
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		884	715	1,717	1,463
Income from equity method investments		111	66	210	136
Assets, Current		2,018		2,018		1,507
Liabilities, Current		$ 2,741		$ 2,741		3,348
MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%		25.00%
Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35.00%		35.00%
LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41.00%		41.00%
Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%		67.00%
Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17.00%		17.00%
Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38.00%		38.00%
Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%		25.00%
W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%		50.00%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57.00%		57.00%
Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%		50.00%
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%		67.00%
MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		60.00%		60.00%
Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		78.00%		78.00%
Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40.00%		40.00%
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		9.19%		9.19%
Indirect Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.55%		24.55%
Direct Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		51.00%		51.00%
G&P | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	$ 683		$ 683		680
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	535		535		544
G&P | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	339		339		332
G&P | MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	286		286		246
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	143		143		147
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	130		130		136
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		134		134		133
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	44		44		45
L&S | MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	493		493		449
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		244		244		243
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		278		278		265
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	180		180		183
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		182		182		183
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	174		174		155
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		59		59		66
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	59		59		58
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	136		136		116
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Equity method investments		2,294		2,294		2,263
Revenues	[3]	1,520	1,036	2,793	2,081
Income from equity method investments		52	31	99	65
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Equity method investments		1,805		1,805		1,718
Revenues	[3]	1,420	1,359	2,757	2,653
Income from equity method investments		59	$ 35	111	71
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues				1,187	943
Costs and Expenses				578	501
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest				609	442
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest				555	388
Assets, Current		757		757		746
Assets, Noncurrent		12,645		12,645		12,334
Liabilities, Current		541		541		527
Liabilities, Noncurrent		3,269		3,269		3,249
Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues				637	607
Costs and Expenses				279	284
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest				358	323
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest				328	283
Income from equity method investments				86	63
Assets, Current		394		394		411
Assets, Noncurrent		5,062		5,062		4,895
Liabilities, Current		249		249		310
Liabilities, Noncurrent		805		805		788
Other VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues				550	336
Costs and Expenses				299	217
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest				251	119
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest				227	105
Income from equity method investments				124	$ 73
Assets, Current		363		363		335
Assets, Noncurrent		7,583		7,583		7,439
Liabilities, Current		292		292		217
Liabilities, Noncurrent		$ 2,464		$ 2,464		$ 2,461

[1] Investments deemed to be VIEs. Some investments included within Other have also been deemed to be VIEs.

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

[3] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $293 million for the three and six months ended June 30, 2022, respectively, and $138 million and $267 million for the three and six months ended June 30, 2021, respectively. Third party revenues for the G&P segment were $1,454 million and $2,666 million for the three and six months ended June 30, 2022, respectively, and $988 million and $1,977 million for the three and six months ended June 30, 2021, respectively.

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Related Party Agreements and Transactions MPC Loan Agreement (Details) - Related Party Revolving Credit Agreement [Member] - MPC Investment [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
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
Related party debt - borrowings	$ 2,824	$ 4,435
Line of Credit Facility, Interest Rate During Period	1.458%	1.354%
Repayments of Related Party Debt	$ 4,274	$ 3,942
Line of Credit, Current	$ 0	$ 493	$ 1,450

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Related Party Disclosures (Details) - Marathon Petroleum Corporation [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Related Party Transaction [Line Items]
Sales Revenue, Goods, Related Party, Net Zero	$ 281	$ 177	$ 574	$ 345
Asset under Construction [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 19	$ 15	$ 38	$ 27

XML

Summary of Charges for Employee Services and Omnibus Agreements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Related Party Transaction [Line Items]
General and Administrative Expense	$ 82	$ 87	$ 160	$ 173
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
General and Administrative Expense	58	63	113	120
Asset under Construction [Member] | Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 19	$ 15	$ 38	$ 27

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Other Assets and Liabilities from Related Parties (Details) - USD ($) $ in Millions		Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Sales-type Lease, Unguaranteed Residual Asset				$ 14
Affiliated Entity
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties, Current		$ 628	$ 555
Prepaid Expense, Current		10	4
Other current assets		2	3
Sales-type Lease, Interest Income		91	82
Current Assets, Related Parties		731	644
Accounts Receivable, Related Parties, Noncurrent		27	31
Operating Lease, Right-of-Use Asset		229	229
Net Investment in Lease, Noncurrent		822	854
Sales-type Lease, Unguaranteed Residual Asset		64	47
Due from Related Parties, Noncurrent		1,142	1,161
Accounts Payable, Related Parties, Current	[1]	329	1,702
Operating Lease, Liability, Current		1	1
Deferred Revenue, Current		57	60	78	$ 91
Due to Related Parties, Current		403	1,780
Operating Lease, Liability, Noncurrent		228	228
Liabilities, Related Parties, Noncurrent		303	302
MPC Investment [Member] | Related Party Revolving Credit Agreement [Member]
Related Party Transaction [Line Items]
Line of Credit, Current		0	1,450	$ 493
Minimum Committed Volume Contracts [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Deferred Revenue, Current		32	35
Reimbursable Projects [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Deferred Revenue, Current		41	42
Long-term deferred revenue		$ 75	$ 74

[1] Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in Current liabilities - related parties on the Consolidated Balance Sheets. There were no borrowings outstanding on the intercompany loan with MPC as of June 30, 2022.

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Equity - Changes in Partners Capital, Unit Rollforward (Details) - USD ($) $ / shares in Units, $ in Millions						3 Months Ended				6 Months Ended		11 Months Ended
	Aug. 15, 2022	Jul. 26, 2022	Apr. 26, 2022	Jul. 27, 2021	Apr. 27, 2021	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2023	Aug. 02, 2022	Dec. 31, 2021	Nov. 02, 2020
Stockholders Equity [Line Items]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						$ (724)	$ (746)	$ (717)	$ (745)
Distribution Made to Limited Partner, Cash Distributions Declared						$ 745		$ 736		$ 1,490	$ 1,474
Stock Repurchase Program, Authorized Amount															$ 1,000
Treasury Stock Acquired, Average Cost Per Share						$ 33.74		$ 27.40		$ 32.48	$ 26.02
Stock Repurchase Program, Remaining Authorized Repurchase Amount						$ 202				$ 202
Cash distributions declared per limited partner common unit			$ 0.7050	$ 0.6875	$ 0.6875
Payments for Repurchase of Common Stock						$ 35		$ 155		$ 135	$ 310
Limited Partners Common Units [Member]
Stockholders Equity [Line Items]
Balance at December 31, 2021							1,016,178,378			1,016,178,378
Unit-based compensation awards										183,478
Stock Repurchased and Retired During Period, Shares						1,000,000		6,000,000		4,156,956	12,000,000
Balance at June 30, 2022						1,012,204,900				1,012,204,900
Distribution Made to Limited Partner, Cash Distributions Declared						$ 714		$ 705		$ 1,427	$ 1,412
Series B Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred Units, Outstanding						600,000				600,000				600,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders						$ 0	$ (21)	0	$ (21)
Subsequent Event
Stockholders Equity [Line Items]
Stock Repurchase Program, Authorized Amount													$ 1,000
Cash distributions declared per limited partner common unit		$ 0.7050
Series B Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred Units, Outstanding						600,000				600,000
Dividend rate, percentage										6.875%
Price per share						$ 1,000				$ 1,000
Preferred Stock, Redemption Terms										MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023 at the Series B preferred unit redemption price of $1,000 per unit, plus any accumulated and unpaid distributions up to the redemption date.
Series B Preferred Stock [Member] | Preferred Partner [Member]
Stockholders Equity [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared						$ 10		$ 10		$ 21	$ 21
Cash distributions declared per limited partner common unit										$ 68.75
Series B Preferred Stock [Member] | Subsequent Event
Stockholders Equity [Line Items]
Dividend rate, percentage												4.652%
Preferred Stock, Dividend Payment Rate, Variable												LIBOR plus
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	$ (21)

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Equity - Cash Distributions (Details) - USD ($) $ / shares in Units, $ in Millions								3 Months Ended				6 Months Ended		11 Months Ended
	Aug. 15, 2022	Aug. 12, 2022	Aug. 05, 2022	Jul. 26, 2022	Apr. 26, 2022	Jul. 27, 2021	Apr. 27, 2021	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2023
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared								$ 745		$ 736		$ 1,490	$ 1,474
Cash distributions declared per limited partner common unit					$ 0.7050	$ 0.6875	$ 0.6875
Partners' Capital Account, Distributions								$ 724	$ 746	717	$ 745
Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Preferred Units, Outstanding								600,000				600,000
Preferred Stock, Dividend Rate, Percentage												6.875%
Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Declaration Date				Jul. 26, 2022
Cash distributions declared per limited partner common unit				$ 0.7050
Distribution date		Aug. 12, 2022
Date of record			Aug. 05, 2022
Subsequent Event | Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Preferred Stock, Dividend Payment Rate, Variable														LIBOR plus
Distribution date	Aug. 15, 2022
Partners' Capital Account, Distributions	$ 21
Preferred Stock, Dividend Rate, Percentage														4.652%
Limited Partners Common Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared								$ 714		705		$ 1,427	1,412
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared								21		21		42	41
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								$ 10		$ 10		$ 21	$ 21
Cash distributions declared per limited partner common unit												$ 68.75

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Net Income Per Limited Partner Unit - Schedule of Distributions by Partner by Class (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	$ 875	$ 706	$ 1,700	$ 1,445
Distribution Made to Limited Partner, Cash Distributions Declared		745	736	1,490	1,474
Undistributed net income (loss) attributable to MPLX LP		130	(30)	210	(29)
Limited Partners Common Units [Member]
Net Income Per Share [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		714	705	1,427	1,412
Undistributed net income (loss) attributable to MPLX LP		126	(30)	204	(29)
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	25	21	48	41
Distribution Made to Limited Partner, Cash Distributions Declared		21	21	42	41
Undistributed net income (loss) attributable to MPLX LP		4	0	6	0
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	10	10	21	21
Distribution Made to Limited Partner, Cash Distributions Declared		10	10	21	21
Undistributed net income (loss) attributable to MPLX LP		0	0	0	0
Common Stock | Limited Partners Common Units [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	$ 840	$ 675	$ 1,631	$ 1,383

[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.

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Net Income Per Limited Partner Unit - Basic and Diluted Earnings Per Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Weighted average units outstanding:
Common - basic (in shares)		1,012	1,029	1,013	1,033
Common - diluted (in shares)		1,012	1,029	1,014	1,033
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax		$ 0.83	$ 0.66	$ 1.61	$ 1.34
Common - diluted (in USD per unit)		$ 0.83	$ 0.66	$ 1.61	$ 1.34
Distribution Made to Limited Partner, Cash Distributions Declared		$ 745	$ 736	$ 1,490	$ 1,474
Undistributed net income (loss) attributable to MPLX LP		130	(30)	210	(29)
Net Income (Loss) Attributable to Parent	[1]	$ 875	$ 706	$ 1,700	$ 1,445
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1	1	1	1
Limited Partners Common Units [Member]
Weighted average units outstanding:
Distribution Made to Limited Partner, Cash Distributions Declared		$ 714	$ 705	$ 1,427	$ 1,412
Undistributed net income (loss) attributable to MPLX LP		126	(30)	204	(29)
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Weighted average units outstanding:
Distribution Made to Limited Partner, Cash Distributions Declared		21	21	42	41
Undistributed net income (loss) attributable to MPLX LP		4	0	6	0
Net Income (Loss) Attributable to Parent	[1]	25	21	48	41
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Weighted average units outstanding:
Distribution Made to Limited Partner, Cash Distributions Declared		10	10	21	21
Undistributed net income (loss) attributable to MPLX LP		0	0	0	0
Net Income (Loss) Attributable to Parent	[1]	10	10	21	21
Common Stock | Limited Partners Common Units [Member]
Weighted average units outstanding:
Net Income (Loss) Attributable to Parent	[1]	$ 840	$ 675	$ 1,631	$ 1,383

[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.

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Segment Information (Details)	6 Months Ended
	Jun. 30, 2022
Segment Reporting [Abstract]
Number of reportable segments	2

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Segment Information - Segment Adjusted EBITDA (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Income from equity method investments		$ 111	$ 66	$ 210	$ 136
Total segment revenues and other income		(2,940)	(2,395)	(5,550)	(4,734)
Payments to Acquire Equity Method Investments				(156)	(84)
L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,017	996	2,004	1,953
G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,365	900	2,512	1,805
Operating Segments
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		2,382	1,896	4,516	3,758
Adjusted EBITDA		1,457	1,374	2,850	2,726
Operating Segments | L&S
Segment Reporting Information [Line Items]
Operating Lease, Lease Income		208	176	383	425
Sales-type Lease, Revenue		114	136	225	173
Income from equity method investments		59	35	111	71
Other income		22	16	34	31
Total segment revenues and other income	[1]	(1,420)	(1,359)	(2,757)	(2,653)
Adjusted EBITDA	[2]	966	947	1,870	1,843
Capital Expenditure		81	76	158	135
Payments to Acquire Equity Method Investments		(10)	(13)	(78)	(22)
Operating Segments | G&P
Segment Reporting Information [Line Items]
Operating Lease, Lease Income		92	91	173	183
Income from equity method investments		52	31	99	65
Other income		11	14	9	28
Total segment revenues and other income	[1]	(1,520)	(1,036)	(2,793)	(2,081)
Adjusted EBITDA	[2]	491	427	980	883
Capital Expenditure		95	36	190	66
Payments to Acquire Equity Method Investments		(36)	(36)	(78)	(62)
Service [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,010	992	1,993	1,945
Service [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		505	493	991	1,001
Product [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		7	4	11	8
Product [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		860	407	1,521	804
Third Party [Member] | L&S
Segment Reporting Information [Line Items]
Total segment revenues and other income		(158)	(138)	(293)	(267)
Third Party [Member] | G&P
Segment Reporting Information [Line Items]
Total segment revenues and other income		$ (1,454)	$ (988)	$ (2,666)	$ (1,977)

[1] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $293 million for the three and six months ended June 30, 2022, respectively, and $138 million and $267 million for the three and six months ended June 30, 2021, respectively. Third party revenues for the G&P segment were $1,454 million and $2,666 million for the three and six months ended June 30, 2022, respectively, and $988 million and $1,977 million for the three and six months ended June 30, 2021, respectively.

[2] See below for the reconciliation from Segment Adjusted EBITDA to Net income.

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Segment Information - Reconciliation to Net Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization	[1]	$ (310)	$ (318)	$ (623)	$ (647)
Asset Impairment Charges		0	42	0	42
Income from equity method investments		111	66	210	136
Proceeds from Equity Method Investment, Distribution				(258)	(239)
Net income		884	715	1,717	1,463
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA		1,457	1,374	2,850	2,726
Segment Reconciling Items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Interest and Other Financial Costs		(233)	(216)	(455)	(441)
Proceeds from Equity Method Investment, Distribution		(152)	(121)	(284)	(242)
Other Cost and Expense, Operating		1	(38)	0	(47)
Adjusted EBITDA attributable to noncontrolling interests		10	10	19	20
L&S
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization		(129)	(136)	(259)	(283)
L&S | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[2]	966	947	1,870	1,843
Income from equity method investments		59	35	111	71
G&P
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization		(181)	(182)	(364)	(364)
G&P | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[2]	491	427	980	883
Income from equity method investments		$ 52	$ 31	$ 99	$ 65

[1] Depreciation and amortization attributable to L&S was $129 million and $259 million for the three and six months ended June 30, 2022, respectively, and $136 million and $283 million for the three and six months ended June 30, 2021, respectively. Depreciation and amortization attributable to G&P was $181 million and $364 million for the three and six months ended June 30, 2022, respectively, and $182 million and $364 million for the three and six months ended June 30, 2021, respectively.

[2] See below for the reconciliation from Segment Adjusted EBITDA to Net income.

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Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	$ 26,754		$ 26,754		$ 26,546
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization	6,987		6,987		6,504	[1]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	19,767		19,767		20,042
Asset Impairment Charges	0	$ 42	0	$ 42
L&S
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	12,442		12,442		12,371
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization	3,424		3,424		3,227
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	9,018		9,018		9,144
G&P
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	14,312		14,312		14,175
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization	3,563		3,563		3,277	[1]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	$ 10,749		$ 10,749		$ 10,898

[1] Includes property, plant and equipment impairment charges recorded in the second quarter of 2021, as discussed below.

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Fair Value Measurements - Recurring - Financial Instruments by Valuation Hierarchy (Details) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	(92,000,000)	(108,000,000)
Embedded Derivative Financial Instruments [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	92,000,000	$ 108,000,000
Minimum [Member] | Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs Forward Commodity Price	0.72
Maximum [Member] | Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs Forward Commodity Price	$ 1.98

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Fair Value Measurments - Recurring - Significant Unobservable Inputs in Level 3 Valuation (Details)	6 Months Ended
	Jun. 30, 2022 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.98
Embedded Derivative Financial Instruments [Member] | Natural Gas [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Embedded Derivative Renewal Term	5 years
Fair Value, Inputs, Level 3 [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Probability of Renewal	100.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Forward Commodity Price	$ 0.72
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Forward Commodity Price	$ 1.98

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Fair Value Measurements - Recurring - Changes in Level 3 Measurements (Details) - Embedded Derivatives in Commodity Contracts (net) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value at beginning of period		$ (99)	$ (66)	$ (108)	$ (63)
Total gains (losses) (realized and unrealized) included in earnings	[1]	4	(39)	8	(45)
Settlements		3	3	8	6
Fair value at end of period		(92)	(102)	(92)	(102)
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		$ 3	$ (39)	$ 8	$ (41)

[1] Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs on the Consolidated Statements of Income.

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Fair Value Measurements - Reported (Details) - USD ($) $ in Millions		Jun. 30, 2022	Dec. 31, 2021
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	[1]	$ 19,881	$ 18,664
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	[1]	$ 18,604	$ 20,779

[1] Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

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Derivative Financial Instruments - Embedded Derivatives in Commodity Contracts (Details) - Embedded Derivative Financial Instruments [Member] $ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Liability	$ (92)	$ (108)
Natural Gas [Member]
Derivative [Line Items]
Number of Renewals	1
Embedded Derivative Renewal Term	5 years

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Derivative Financial Instruments - Derivatives Balance Sheet Location (Details) - Not Designated as Hedging Instrument [Member] - Commodity Contract [Member] - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	92	108
Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	14	15
Other noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 78	$ 93

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Derivatives Financial Instruments - Derivative Income Statement Location (Details) - Purchased product costs - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Derivative [Line Items]
Realized gain (loss)	$ (3)	$ (3)	$ (8)	$ (6)
Total gain (loss)	4	(39)	8	(45)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ 7	$ (36)	$ 16	$ (39)

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Debt - Summary of Outstanding Borrowings (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Line of Credit	$ 0	$ 300
Financing lease obligations	8	9
Total	20,108	18,909
Unamortized debt issuance costs	(114)	(102)
Unamortized discount	(219)	(236)
Long-term Debt and Lease Obligation, Current	1,000	499
Total long-term debt due after one year	18,775	18,072
MPLX LP [Member]
Debt Instrument [Line Items]
Senior Notes	20,032	18,532
MarkWest [Member]
Debt Instrument [Line Items]
Senior Notes	23	23
ANDX LP [Member]
Debt Instrument [Line Items]
Senior Notes	$ 45	$ 45

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Debt - Additional Information (Detail) - USD ($) $ in Millions			6 Months Ended
	Jul. 07, 2022	Mar. 14, 2022	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Line of Credit			$ 0	$ 300
Finance Lease, Liability			8	9
Debt and Lease Obligation			20,108	18,909
Unamortized Debt Issuance Expense			114	102
Debt Instrument, Unamortized Discount			219	236
Long-term debt			18,775	$ 18,072
MPLX Revolving Credit Facility due June 2027 | Subsequent Event
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,000
Letter of Credit, Issuing Capacity	$ 150
Debt Instrument, Description of Variable Rate Basis	Adjusted Term SOFR or the Alternate Base Rate, both as defined in the New MPLX Credit Agreement, plus an applicable margin.
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit			$ 900
Debt Instrument, Interest Rate, Effective Percentage			1.454%
Repayments of Long-term Lines of Credit			$ 1,200
Line of Credit Facility, Remaining Borrowing Capacity			3,500
Long-term Line of Credit			0
Line of Credit Facility, Maximum Borrowing Capacity			3,500
MPLX Revolving Credit Facility due July 2024 [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding			$ 1
Senior Notes [Member] | Senior Note Due March 2052 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.95%
Percent of Par		98.982%
Debt Instrument, Face Amount		$ 1,500
Debt Instrument, Issuance Date		Mar. 14, 2022
Minimum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			1.75%
Maximum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.50%

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Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]		Product and Service, Other [Member]	Product and Service, Other [Member]	Product and Service, Other [Member]	Product and Service, Other [Member]
Revenue Not from Contract with Customer, Other	[1]	$ 558	$ 499	$ 1,034	$ 976
Revenues		2,940	2,395	5,550	4,734
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,382	1,896	4,516	3,758
L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,017	$ 996	$ 2,004	$ 1,953
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]		Product and Service, Other [Member]	Product and Service, Other [Member]	Product and Service, Other [Member]	Product and Service, Other [Member]
L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[2]	$ 1,420	$ 1,359	$ 2,757	$ 2,653
G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,365	$ 900	$ 2,512	$ 1,805
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]		Product and Service, Other [Member]	Product and Service, Other [Member]	Product and Service, Other [Member]	Product and Service, Other [Member]
G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[2]	$ 1,520	$ 1,036	$ 2,793	$ 2,081
Service [Member] | Affiliated Entity
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		938	907	1,853	1,779
Service [Member] | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		577	578	1,131	1,167
Service [Member] | L&S | Affiliated Entity
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		933	901	1,844	1,770
Service [Member] | L&S | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		77	91	149	175
Service [Member] | L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,010	992	1,993	1,945
Service [Member] | G&P | Affiliated Entity
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		5	6	9	9
Service [Member] | G&P | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		500	487	982	992
Service [Member] | G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		505	493	991	1,001
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		118	76	241	153
Service, Other [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0	0	0
Service, Other [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		118	76	241	153
Product [Member] | Affiliated Entity
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		51	31	96	73
Product [Member] | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		698	304	1,195	586
Product [Member] | L&S | Affiliated Entity
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		5	3	8	6
Product [Member] | L&S | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2	1	3	2
Product [Member] | L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		7	4	11	8
Product [Member] | G&P | Affiliated Entity
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		46	28	88	67
Product [Member] | G&P | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		696	303	1,192	584
Product [Member] | G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 860	$ 407	$ 1,521	$ 804

[1] Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

[2] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $158 million and $293 million for the three and six months ended June 30, 2022, respectively, and $138 million and $267 million for the three and six months ended June 30, 2021, respectively. Third party revenues for the G&P segment were $1,454 million and $2,666 million for the three and six months ended June 30, 2022, respectively, and $988 million and $1,977 million for the three and six months ended June 30, 2021, respectively.

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Revenue Contract Balances (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Contract with Customer, Asset, before Allowance for Credit Loss		$ 11	$ 16	$ 25	$ 40
Contract assets, additions/(deletions)		(14)	(25)
Contract assets, revenue recognized	[1]	0	1
Contract with Customer, Asset, before Allowance for Credit Loss, Noncurrent		2	2	2	2
Contract with Customer, Asset Increase (Decrease), Noncurrent		0	0
Contract With Customer Non Current Asset Reclassified To Receivable [Line Items]	[1]	0	0
Contract Liability, Noncurrent, Period Increase (Decrease)		0	0
Contract Liability, Noncurrent, Revenue Recognized	[1]	0	0
Liability, change in timeframe, performance obligation satisfied, revenue recognized		0	0
Other Noncurrent Liabilities [Member]
Contract with Customer, Liability, Noncurrent		5	6	5	6
Affiliated Entity
Deferred Revenue, Current		57	78	60	91
Deferred revenue, additions/(deletions)		54	37
Deferred revenue, revenue recognized	[1]	(57)	(50)
Long-term deferred revenue, additions/(deletions)		(3)	(8)
Long-term deferred revenue, revenue recognized	[1]	0	0
Affiliated Entity | Due to related parties, noncurrent
Contract with Customer, Liability, Noncurrent		28	40	31	48
Third Party [Member]
Deferred Revenue, Current		57	44	56	37
Deferred revenue, additions/(deletions)		26	24
Deferred revenue, revenue recognized	[1]	(25)	(17)
Long-term deferred revenue, additions/(deletions)		17	9
Long-term deferred revenue, revenue recognized	[1]	0	0
Third Party [Member] | Deferred revenue, noncurrent
Contract with Customer, Liability, Noncurrent		$ 152	$ 128	$ 135	$ 119

[1] No significant revenue was recognized related to past performance obligations in the current periods.

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Revenue Remaining Performance Obligations (Details) $ in Millions	Jun. 30, 2022 USD ($)
Revenue from Contract with Customer [Abstract]
Contract with customer, liability	$ 293
Revenue, Remaining Performance Obligation, Amount	9,039	[1],[2],[3]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 943
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,727
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]: 2024-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,601
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]: 2025-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,530
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]: 2026-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,373
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	4 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,865
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	5 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2043-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	22 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 and sales-type leases are excluded from this table.

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

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Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities	$ 393	$ 414
Income Taxes Paid, Net	$ 1	$ 1

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Supplemental Cash Flow Information - Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Increase/ (decrease) in capital accruals	$ 54	$ (34)

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Leases, Codification Topic 842 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Lessor, Lease, Description [Line Items]
Sales-type Lease, Selling Profit (Loss)		$ 112
Lessor, Sales-type Lease, Assumptions and Judgments, Value of Underlying Asset, Amount		421		$ 421
Sales-type Lease, Lease Receivable		519		519
Sales-type Lease, Unguaranteed Residual Asset		14		14
Reclassification, Other
Lessor, Lease, Description [Line Items]
Property, Plant and Equipment, Transfers and Changes			$ 18
Third Party [Member]
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 102	99	193	198
Sales-type Lease, Interest Income	0	0	0	0
Sales-type Lease, Variable Lease Income	0	0	0	0
Sales-type Lease, Lease Receivable	1		1		$ 1
Third Party [Member] | L&S
Lessor, Lease, Description [Line Items]
Sales-type Lease, Revenue	0	0	0	0
Affiliated Entity
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income, Related Party	198	168	363	410
Sales-type Lease, Revenue	114	136	225	173
Sales-type Lease, Interest Income	112	135	222	172
Sales-type Lease, Variable Lease Income	2	$ 1	3	$ 1
Sales-type Lease, Unguaranteed Residual Asset	$ 64		$ 64		$ 47

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Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	6 Months Ended
	Dec. 15, 2020	Jul. 31, 2020	Jun. 30, 2022	Dec. 31, 2021
Commitments And Contingencies [Line Items]
Accrued liabilities for environmental remediation			$ 27	$ 23
Loss Contingency, Damages Sought, Value		$ 187
Loss Contingency, Damages Paid, Value	$ 4
Guarantor Obligations, Origin and Purpose			GuaranteesOver 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.We hold a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. Completion of the EIS may now be delayed as the Army Corps engages with the Standing Rock Sioux Tribe on the tribe’s reasons for withdrawing as a cooperating agency with respect to preparation of the EIS.In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.We have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, has 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. If the pipeline were temporarily shut down, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of June 30, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage			9.19%
Financial Guarantee | Bakken Pipeline System [Member] | Guarantee of Indebtedness of Others
Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 170