MPLX (MPLX) 10-Q 1 Nov 22 2022 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Oct. 28, 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	Sep. 30, 2022
Amendment Flag	false
Entity File Number	001-35714
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
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		1,003,242,909
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

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021	Sep. 30, 2022		Sep. 30, 2021
Sales-type Lease, Revenue		$ 28		$ 0	$ 28		$ 0
Sales-type lease revenue, related parties		118		132	343		305
Operating Lease, Lease Income		75		88	268		286
Operating Lease, Lease Income, Related Party		201		164	564		574
Income from equity method investments		125		92	335		228
Other Income		505	[1]	(2)	494	[1]	2
Related Party Transaction, Other Revenues from Transactions with Related Party		28		27	82		82
Revenues		3,401		2,559	8,951		7,293
Costs and Expenses, Related Party		364		307	1,034		902
Cost, Depreciation and Amortization	[2]	302		324	925		971
Asset Impairment Charges		0		0	0		42
General and Administrative Expense		88		94	248		267
Taxes, Miscellaneous		30		27	97		93
Costs and Expenses		1,727		1,528	5,100		4,357
Interest And Other Financial Costs From Related Parties		0		2	5		4
Other Nonoperating Income (Expense)		19		21	59		67
Interest Expense, Debt, Excluding Amortization		217		197	627		590
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent, Total		1,674		1,031	3,851		2,936
Provision for income taxes		1		0	6		1
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total		1,438		811	3,160		2,275
Less: Net income (loss) attributable to noncontrolling interest		9		9	26		27
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total		1,437		811	3,154		2,274
Limited partners' interest in net income (loss) attributable to MPLX LP		1,395		754	3,032		2,137
Net income (loss) attributable to MPLX LP	[3]	$ 1,428	[4]	$ 802	$ 3,128	[4]	$ 2,247
Net income (loss) attributable to MPLX LP per limited partner unit:
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax		$ 1.36		$ 0.74	$ 2.97		$ 2.07
Common - diluted (in USD per unit)		$ 1.36		$ 0.74	$ 2.97		$ 2.07
Weighted average limited partner units outstanding:
Common - basic (in shares)		1,010		1,024	1,012		1,030
Common - diluted (in shares)		1,011		1,025	1,013		1,030
Third Party [Member]
Direct Costs of Leased and Rented Property or Equipment		$ 22		$ 33	$ 101		$ 97
Service [Member]
Total revenues from contracts with customers		627		600	1,758		1,767
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		948		902	2,801		2,681
Service [Member] | Third Party [Member]
Total revenues from contracts with customers		627		600	1,758		1,767
Service, Other [Member]
Total revenues from contracts with customers		83		82	324		235
Product [Member]
Total revenues from contracts with customers		617		448	1,812		1,034
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		46		26	142		99
Product [Member] | Third Party [Member]
Total revenues from contracts with customers		617		448	1,812		1,034
Oil and Gas, Refining and Marketing [Member]
Cost of Goods and Services Sold		371		298	981		864
Natural Gas, Midstream [Member]
Cost of Goods and Services Sold		540		421	1,670		1,035
Series A Preferred Stock [Member]
Dividends, Preferred Stock		23		38	65		79
Series A Preferred Stock [Member] | Preferred Partner [Member]
Net income (loss) attributable to MPLX LP	[3]	41	[4]	38	89	[4]	79
Series B Preferred Stock [Member]
Dividends, Preferred Stock		10		10	31		31
Series B Preferred Stock [Member] | Preferred Partner [Member]
Net income (loss) attributable to MPLX LP	[3]	10	[4]	10	31	[4]	31
Affiliated Entity
Direct costs of leased and rented property or equipment, related parties		$ 10		$ 24	$ 44		$ 86
[1]The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information.[2]Depreciation and amortization attributable to L&S was $128 million and $387 million for the three and nine months ended September 30, 2022, respectively, and $131 million and $414 million for the three and nine months ended September 30, 2021, respectively. Depreciation and amortization attributable to G&P was $174 million and $538 million for the three and nine months ended September 30, 2022, respectively, and $193 million and $557 million for the three and nine months ended September 30, 2021, respectively. (2)    Includes unrealized derivative gain/ (loss), non-cash equity-based compensation, and other miscellaneous items.[3]Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.[4]The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information.

Consolidated Statements of In_2

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Sales-type Lease, Selling Profit (Loss)	$ 509	$ 509
Other Income
Sales-type Lease, Selling Profit (Loss)	$ 509	$ 509

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 1,437	$ 811	$ 3,154	$ 2,274
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	1,437	811	3,163	2,272
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest [Abstract]
Less: Net income (loss) attributable to noncontrolling interest	9	9	26	27
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 1,428	$ 802	$ 3,137	$ 2,245

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) shares in Millions, $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2022	Sep. 30, 2022	Aug. 01, 2022	Jul. 31, 2022	Dec. 31, 2021	Apr. 30, 2021
Assets
Cash and cash equivalents		$ 121	$ 121			$ 13
Receivables, net		941	941			654
Inventories		151	151			142
Total current assets		1,951	1,951			1,507
Equity method investments		4,108	4,108			3,981
Property, plant and equipment, net		18,910	18,910			20,042
Intangibles, net		736	736			831
Goodwill		7,645	7,645			7,657
Due from Related Parties, Noncurrent		1,222	1,222			1,161
Other noncurrent assets		952	952			60
Total assets		35,812	35,812			35,507
Liabilities
Accounts Payable, Current		289	289			172
Accrued Liabilities, Current		300	300			363
Accrued Property Plant and Equipment Current		111	111			97
Long-term Debt and Lease Obligation, Current		982	982			499
Interest Payable, Current		192	192			202
Other current liabilities		217	217			176
Total current liabilities		2,499	2,499			3,348
Long-term deferred revenue		170	170			383
Long-term debt		18,797	18,797			18,072
Deferred Income Taxes and Other Tax Liabilities, Noncurrent		14	14			10
Other long-term liabilities		130	130			170
Total liabilities		22,169	22,169			22,490
Commitments and contingencies (see Note 15)
Equity
Accumulated other comprehensive loss		(8)	(8)			(17)
Total MPLX LP partners’ capital		12,438	12,438			11,811
Noncontrolling interests		238	238			241
Total equity		12,676	12,676			12,052
Total liabilities, preferred units and equity		35,812	35,812			35,507
Partners' Capital Account, Contributions		55
Sales-type Lease, Selling Profit (Loss)		509	509
Third Party [Member]
Assets
Other current assets		40	40			54
Property, plant and equipment, net					$ 745
Operating Lease, Right-of-Use Asset		288	288			268
Liabilities
Operating Lease, Liability, Current		44	44			59
Long-term deferred revenue					$ 277
Operating Lease, Liability, Noncurrent		241	241			205
Equity
Sales-type Lease, Selling Profit (Loss)	[1]	509	509
Public [Member]
Equity
Limited Partners' Capital Account		8,569	8,569			8,579
Marathon Petroleum Corporation [Member]
Liabilities
Limited Partners' Capital Account, Related Party		3,276	3,276			2,638
Affiliated Entity
Assets
Current Assets, Related Parties		698	698			644
Property, plant and equipment, net				$ 42			$ 421
Liabilities
Due to Related Parties, Current		364	364			1,780
Long-term deferred revenue				$ 0			$ 0
Liabilities, Related Parties, Noncurrent		$ 318	$ 318			$ 302
Limited Partners Common Units [Member] | Public [Member]
Liabilities
Units issued		359	359			369
Units Outstanding		359	359			369
Equity
Limited Partners' Capital Account		$ 8,569	$ 8,569			$ 8,579
Partners' Capital Account, Contributions		$ 0
Limited Partners Common Units [Member] | Marathon Petroleum Corporation [Member]
Liabilities
Units issued		647	647			647
Units Outstanding		647	647			647
Equity
Limited Partners' Capital Account		$ 3,276	$ 3,276			$ 2,638
Partners' Capital Account, Contributions		55
Limited Partners Common Units [Member] | Marathon Petroleum Corporation [Member] | Gain (loss) on sales-type lease
Equity
Partners' Capital Account, Contributions	[2]	43	43
Series A Preferred Stock [Member]
Liabilities
Series A preferred units (30 million and 30 million units issued and outstanding)		967	$ 967			$ 965
Equity
Partners' Capital Account, Contributions		$ 0
Series B Preferred Stock [Member]
Liabilities
Preferred Units, Issued		0.6	0.6			0.6
Preferred Units, Outstanding		0.6	0.6			0.6
Equity
Preferred Units, Preferred Partners' Capital Accounts		$ 601	$ 601			$ 611
Partners' Capital Account, Contributions		$ 0
Series A Convertible Preferred Units
Liabilities
Preferred Units, Issued		30	30			30
Preferred Units, Outstanding		30	30			30
[1]The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income.[2]The amount recognized on commencement date was recorded as a Contribution from MPC in the Consolidated Statements of Equity given the underlying agreements are between entities under common control

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Sep. 30, 2022	Dec. 31, 2021
Limited Partners Common Units [Member] | Public [Member]
Units issued	359	369
Units Outstanding	359	369
Limited Partners Common Units [Member] | Marathon Petroleum Corporation [Member]
Units issued	647	647
Units Outstanding	647	647
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	30
Preferred Units, Outstanding	30	30

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021
Operating activities:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 3,154		$ 2,274
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs		55		53
Cost, Depreciation and Amortization	[1]	925		971
Goodwill and Intangible Asset Impairment		0		42
Deferred income taxes		4		(1)
Sales-type Lease, Selling Profit (Loss)		(509)		0
Loss on disposal of assets		23		4
Income from equity method investments		(335)		(228)
Proceeds from Equity Method Investment, Distribution		405		361
Increase (Decrease) in Derivative Assets and Liabilities		(62)		41
Changes in:
Current receivables		(219)		(162)
Inventories		(7)		(22)
Current accounts payable and accrued liabilities		49		166
Current assets/current liabilities - related parties		52		94
Increase (Decrease) in Other Operating Assets and Liabilities, Net		1		2
Deferred revenue		64		65
All other, net		51		11
Net cash provided by operating activities		3,651		3,671
Net Cash Provided by (Used in) Investing Activities [Abstract]
Additions to property, plant and equipment		(535)		(374)
Payments to Acquire Businesses, Net of Cash Acquired		(28)		0
Disposal of assets		74		77
Payments to Acquire Equity Method Investments		(198)		(116)
Proceeds from Equity Method Investment, Distribution, Return of Capital		11		36
Net cash used in investing activities		(676)		(377)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Long-term debt - borrowings		3,379		3,000
Long-term debt - repayments		(2,202)		(4,946)
Payments of Debt Issuance Costs		29		0
Payments for Repurchase of Common Stock		(315)		(465)
Distributions to noncontrolling interests		(29)		(29)
Distributions to unitholders and general partner		(2,144)		(2,126)
Proceeds from Contributions from Parent		30		31
All other, net		(3)		(3)
Net cash used in financing activities		(2,867)		(3,270)
Net change in cash, cash equivalents and restricted cash		108		24
Cash, cash equivalents and restricted cash at beginning of period		13		15
Cash, cash equivalents and restricted cash at end of period		121		39
Third Party [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Sales-type Lease, Selling Profit (Loss)		(509)	[2]	0
Related Party Revolving Credit Agreement [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Related party debt - borrowings		2,824		6,571
Repayments of Related Party Debt		(4,274)		(5,201)
Series A Preferred Stock [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Distributions to preferred unitholders		(63)		(61)
Series B Preferred Stock [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Distributions to preferred unitholders		$ (41)		$ (41)
[1]Depreciation and amortization attributable to L&S was $128 million and $387 million for the three and nine months ended September 30, 2022, respectively, and $131 million and $414 million for the three and nine months ended September 30, 2021, respectively. Depreciation and amortization attributable to G&P was $174 million and $538 million for the three and nine months ended September 30, 2022, respectively, and $193 million and $557 million for the three and nine months ended September 30, 2021, respectively. (2)    Includes unrealized derivative gain/ (loss), non-cash equity-based compensation, and other miscellaneous items.[2]The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income.

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Series B Preferred Stock [Member]	Series A Preferred Stock [Member]	Public [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
Beginning Balance at Dec. 31, 2020	13,017
Ending Balance at Sep. 30, 2021	12,690
Proceeds from Equity Method Investment, Distribution, Return of Capital	36
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
Beginning Balance at Mar. 31, 2021	12,850
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
Stock Repurchased and Retired During Period, Value	(160)	0	0		(160)	0	0	0
Distributions to:	773	10			(278)	(476)	0	9
Temporary Equity, Dividends, Adjustment			20
Partners' Capital Account, Distributions	(735)	(20)			(261)	(445)	0	(9)
Other	1	0			1	0	0	0
Ending Balance at Sep. 30, 2021	12,690
Temporary Equity, Net Income			38
Partners' Capital Account, Contributions	16	0	0		0	16	0	0
Temporary Equity, Other Changes			0
Preferred Units, Preferred Partners' Capital Accounts		601
Limited Partners' Capital Account					8,919	2,944
Noncontrolling interests	243
Accumulated other comprehensive loss	(17)
Series A preferred units (30 million and 30 million units issued and outstanding)			986
Preferred Units, Preferred Partners' Capital Accounts		611
Limited Partners' Capital Account				$ 8,579	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
Beginning Balance at Dec. 31, 2021	12,052
Ending Balance at Sep. 30, 2022	12,676
Proceeds from Equity Method Investment, Distribution, Return of Capital	11
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
Beginning Balance at Mar. 31, 2022	12,036
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
Stock Repurchased and Retired During Period, Value	(196)	0	0		(196)	0	0	0
Distributions to:	1,414	10			(502)	(893)	0	9
Temporary Equity, Dividends, Adjustment			21
Partners' Capital Account, Distributions	(744)	(20)			(258)	(456)	0	(10)
Other	3	0			3	0	0	0
Ending Balance at Sep. 30, 2022	12,676
Temporary Equity, Net Income			23
Partners' Capital Account, Contributions	55	0	0		0	55	$ 0	$ 0
Temporary Equity, Other Changes			0
Preferred Units, Preferred Partners' Capital Accounts		$ 601
Limited Partners' Capital Account				$ 8,569	$ 8,569	$ 3,276
Noncontrolling interests	238
Accumulated other comprehensive loss	$ (8)
Series A preferred units (30 million and 30 million units issued and outstanding)			$ 967

Description of the Business and

Description of the Business and Basis of Presentation	9 Months Ended
	Sep. 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 These 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 nine months ended September 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 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.

Accounting Standards Accounting

Accounting Standards Accounting Standards	9 Months Ended
	Sep. 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.

Investments and Noncontrolling

Investments and Noncontrolling Interest	9 Months Ended
	Sep. 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 September 30, September 30, December 31, (In millions, except ownership percentages) 2022 2022 2021 L&S MarEn Bakken Company LLC (1) 25% $ 485 $ 449 Illinois Extension Pipeline Company, L.L.C. 35% 247 243 LOOP LLC 41% 283 265 Andeavor Logistics Rio Pipeline LLC (2) 67% 179 183 Minnesota Pipe Line Company, LLC 17% 180 183 Whistler Pipeline LLC (2) 38% 188 155 Explorer Pipeline Company 25% 62 66 W2W Holdings LLC (2) 50% 60 58 Other (2) 148 116 Total L&S 1,832 1,718 G&P MarkWest Utica EMG, L.L.C. (2) 57% 676 680 Sherwood Midstream LLC (2) 50% 515 544 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. (2) 67% 338 332 MarkWest Torñado GP, L.L.C. (2) 60% 301 246 Rendezvous Gas Services, L.L.C. (2) 78% 139 147 Sherwood Midstream Holdings LLC (2) 51% 128 136 Centrahoma Processing LLC 40% 134 133 Other (2) 45 45 Total G&P 2,276 2,263 Total $ 4,108 $ 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 September 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 nine months ended September 30, 2022.

Related Party Agreements and Tr

Related Party Agreements and Transactions	9 Months Ended
	Sep. 30, 2022
Related Party Transactions [Abstract]
Related Party Agreements and Transactions	Related Party Agreements and TransactionsMPLX 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 (the “MPC Loan Agreement”) with MPC Investment LLC (“MPC Investment”). Under the terms of the MPC Loan 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 MPC 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: Nine Months Ended (In millions) 2022 2021 Borrowings $ 2,824 $ 6,571 Weighted average interest rate of borrowings 1.458 % 1.345 % Repayments $ 4,274 $ 5,201 Outstanding balance at end of period $ — $ 1,370 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 in 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 nine months ended September 30, 2022, these sales totaled $235 million and $809 million, respectively. For the three and nine months ended September 30, 2021, these sales totaled $203 million and $548 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 nine months ended September 30, 2022, General and administrative expenses incurred from MPC totaled $60 million and $173 million, respectively. For the three and nine months ended September 30, 2021, General and administrative expenses incurred from MPC totaled $70 million and $190 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 in the Consolidated Balance Sheets. For the three and nine months ended September 30, 2022, these charges totaled $16 million and $54 million, respectively. For the three and nine months ended September 30, 2021, these charges totaled $13 million and $40 million, respectively. Related Party Assets and Liabilities Assets and liabilities with related parties appearing in 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) September 30, December 31, Current assets - related parties Receivables $ 581 $ 555 Lease receivables 102 82 Prepaid 12 4 Other 3 3 Total 698 644 Noncurrent assets - related parties Long-term lease receivables 889 854 Right of use assets 229 229 Unguaranteed residual asset 77 47 Long-term receivables 27 31 Total 1,222 1,161 Current liabilities - related parties MPC loan agreement and other payables (1) 291 1,702 Deferred revenue - project reimbursements 38 42 Deferred revenue - minimum volume deficiencies 34 35 Operating lease liabilities 1 1 Total 364 1,780 Long-term liabilities - related parties Long-term operating lease liabilities 227 228 Long-term deferred revenue - project reimbursements 91 74 Total $ 318 $ 302 (1) Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the MPC Loan Agreement, 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 September 30, 2022.

Equity

Equity	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Equity	Equity The changes in the number of common units during the nine months ended September 30, 2022 are summarized below: (In units) Common Units Balance at December 31, 2021 1,016,178,378 Unit-based compensation awards 190,529 Units redeemed in unit repurchase program (10,353,035) Balance at September 30, 2022 1,006,015,872 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. On August 2, 2022, we announced the board authorization for the repurchase of up to an additional $1 billion of MPLX common units held by the public. 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 and amount of future repurchases, if any, will depend upon several factors, including market and business conditions, and such repurchases may be discontinued at any time. Total unit repurchases were as follows for the respective periods: Three Months Ended Nine Months Ended (In millions, except per unit data) 2022 2021 2022 2021 Number of common units repurchased 6 6 10 18 Cash paid for common units repurchased $ 180 $ 155 $ 315 $ 465 Average cost per unit $ 31.65 $ 28.41 $ 31.98 $ 26.79 As of September 30, 2022, we had $1,006 million remaining under the unit repurchase authorization, which reflects the repurchase of 532,326 common units for $16 million that were transacted in the third quarter of 2022 and settled in the fourth quarter of 2022. 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 November 1, 2022, MPLX declared a cash distribution for the third quarter of 2022, totaling $777 million, or $0.7750 per common unit. This distribution will be paid on November 22, 2022 to common unitholders of record on November 15, 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 September 30, (1) $ 0.7750 $ 1.2800 (1) Includes a supplemental distribution amount of $0.575 per common unit declared and paid during the fourth quarter of 2021 (the “Supplemental Distribution Amount”). In accordance with the distribution rights discussed above, MPLX made cash distributions of $21 million to Series B unitholders on February 15, 2022 and August 15, 2022. The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three and nine months ended September 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 Nine Months Ended (In millions) 2022 2021 2022 2021 Common and preferred unit distributions: Common unitholders, includes common units of general partner (1) $ 777 $ 1,305 $ 2,204 $ 2,717 Series A preferred unit distributions (1) 23 38 65 79 Series B preferred unit distributions 10 10 31 31 Total cash distributions declared $ 810 $ 1,353 $ 2,300 $ 2,827 (1) 2021 periods include the Supplemental Distribution Amount.

Net Income Per Limited Partner

Net Income Per Limited Partner Unit	9 Months Ended
	Sep. 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 nine months ended September 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 nine months ended September 30, 2022 and 2021 were less than 1 million. Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Net income attributable to MPLX LP (1) $ 1,428 $ 802 $ 3,128 $ 2,247 Less: Distributions declared on Series A preferred units (2) 23 38 65 79 Distributions declared on Series B preferred units 10 10 31 31 Limited partners’ distributions declared on MPLX common units (including common units of general partner) (2) 777 1,305 2,204 2,717 Undistributed net gain/ (loss) attributable to MPLX LP $ 618 $ (551) $ 828 $ (580) (1) The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information. (2) 2021 periods include the Supplemental Distribution Amount. Three Months Ended September 30, 2022 (In millions, except per unit data) Limited Partners’ 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 $ 777 $ 23 $ 10 $ 810 Undistributed net gain attributable to MPLX LP (1) 600 $ 18 — 618 Net income attributable to MPLX LP (2) $ 1,377 $ 41 $ 10 $ 1,428 Weighted average units outstanding: Basic 1,010 Diluted 1,011 Net income attributable to MPLX LP per limited partner unit: Basic $ 1.36 Diluted $ 1.36 (1) The undistributed net gain attributable to MPLX LP includes a $509 million non-cash gain on a lease reclassification for the three months ended September 30, 2022. See Note 14 for additional information. (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. Three Months Ended September 30, 2021 (In millions, except per unit data) Limited Partners’ 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) $ 1,305 $ 38 $ 10 $ 1,353 Undistributed net loss attributable to MPLX LP (551) — — (551) Net income attributable to MPLX LP (2) $ 754 $ 38 $ 10 $ 802 Weighted average units outstanding: Basic 1,024 Diluted 1,025 Net income attributable to MPLX LP per limited partner unit: Basic $ 0.74 Diluted $ 0.74 (1) Includes the Supplemental Distribution Amount. (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. Nine Months Ended September 30, 2022 (In millions, except per unit data) Limited Partners’ 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 $ 2,204 $ 65 $ 31 $ 2,300 Undistributed net gain attributable to MPLX LP (1) 804 24 — 828 Net income attributable to MPLX LP (2) $ 3,008 $ 89 $ 31 $ 3,128 Weighted average units outstanding: Basic 1,012 Diluted 1,013 Net income attributable to MPLX LP per limited partner unit: Basic $ 2.97 Diluted $ 2.97 (1) The undistributed net gain attributable to MPLX LP includes a $509 million non-cash gain on a lease reclassification for the nine months ended September 30, 2022. See Note 14 for additional information. (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. Nine Months Ended September 30, 2021 (In millions, except per unit data) Limited Partners’ 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) $ 2,717 $ 79 $ 31 $ 2,827 Undistributed net loss attributable to MPLX LP (580) — — (580) Net income attributable to MPLX LP (2) $ 2,137 $ 79 $ 31 $ 2,247 Weighted average units outstanding: Basic 1,030 Diluted 1,030 Net income attributable to MPLX LP per limited partner unit: Basic $ 2.07 Diluted $ 2.07 (1) Includes the Supplemental Distribution Amount. (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.

Segment Information

Segment Information	9 Months Ended
	Sep. 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) gain on sales-type leases; (vii) noncontrolling interests; and (viii) 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 Nine Months Ended (In millions) 2022 2021 2022 2021 L&S Service revenue $ 1,038 $ 983 $ 3,031 $ 2,928 Rental income 210 172 593 597 Product related revenue 4 3 15 11 Sales-type lease revenue 118 132 343 305 Income from equity method investments 72 41 183 112 Other income 8 15 42 46 Total segment revenues and other income (1) 1,450 1,346 4,207 3,999 Segment Adjusted EBITDA (2) 969 904 2,839 2,747 Capital expenditures 80 85 238 220 Investments in unconsolidated affiliates 12 9 90 31 G&P Service revenue 537 519 1,528 1,520 Rental income 66 80 239 263 Product related revenue 742 553 2,263 1,357 Sales-type lease revenue 28 — 28 — Income from equity method investments 53 51 152 116 Other income (3) 525 10 534 38 Total segment revenues and other income (1) 1,951 1,213 4,744 3,294 Segment Adjusted EBITDA (2) 502 485 1,482 1,368 Capital expenditures 146 69 336 135 Investments in unconsolidated affiliates $ 30 $ 23 $ 108 $ 85 (1) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $175 million and $468 million for the three and nine months ended September 30, 2022, respectively, and $138 million and $405 million for the three and nine months ended September 30, 2021, respectively. Third party revenues for the G&P segment were $1,885 million and $4,551 million for the three and nine months ended September 30, 2022, respectively, and $1,170 million and $3,147 million for the three and nine months ended September 30, 2021, respectively. (2) See below for the reconciliation from Segment Adjusted EBITDA to Net income. (3) The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information. The table below provides a reconciliation between Net income and Segment Adjusted EBITDA. Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Reconciliation to Net income: L&S Segment Adjusted EBITDA $ 969 $ 904 $ 2,839 $ 2,747 G&P Segment Adjusted EBITDA 502 485 1,482 1,368 Total reportable segments 1,471 1,389 4,321 4,115 Depreciation and amortization (1) (302) (324) (925) (971) Gain on sales-type leases 509 — 509 — Impairment expense — — — (42) Interest and other financial costs (236) (220) (691) (661) Income from equity method investments 125 92 335 228 Distributions/adjustments related to equity method investments (166) (129) (450) (371) Other (2) 26 (6) 26 (53) Adjusted EBITDA attributable to noncontrolling interests 10 9 29 29 Net income $ 1,437 $ 811 $ 3,154 $ 2,274 (1) Depreciation and amortization attributable to L&S was $128 million and $387 million for the three and nine months ended September 30, 2022, respectively, and $131 million and $414 million for the three and nine months ended September 30, 2021, respectively. Depreciation and amortization attributable to G&P was $174 million and $538 million for the three and nine months ended September 30, 2022, respectively, and $193 million and $557 million for the three and nine months ended September 30, 2021, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 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: September 30, 2022 December 31, 2021 (In millions) Gross PP&E Accumulated Depreciation Net PP&E Gross PP&E Accumulated Depreciation Net PP&E L&S $ 12,373 $ 3,456 $ 8,917 $ 12,371 $ 3,227 $ 9,144 G&P 13,389 3,396 9,993 14,175 3,277 10,898 Total $ 25,762 $ 6,852 $ 18,910 $ 26,546 $ 6,504 $ 20,042 We capitalize interest as part of the cost of major projects during the construction period. Capitalized interest totaled $2 million and $7 million for the three and nine months ended September 30, 2022, respectively. Capitalized interest totaled $2 million and $12 million for the three and nine months ended September 30, 2021, respectively. 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.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 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 $0.51 to $1.56 per gallon with a weighted average of $0.75 per gallon and (2) the probability of renewal of 100 percent for the five Changes in Level 3 Fair Value Measurements The following table is a reconciliation of the net beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Beginning balance $ (92) $ (102) $ (108) $ (63) Unrealized and realized gain/ (loss) included in net income (1) 44 (7) 52 (52) Settlements 2 5 10 11 Ending balance (46) (104) (46) (104) 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 $ 42 $ (6) $ 50 $ (44) (1) Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs in the Consolidated Statements of Income. Fair Values – Non-recurring Non-recurring fair value measurements and disclosures relate primarily to MPLX’s sales-type leases as discussed in Note 14. The net investment in sales-type leases is recorded at the estimated fair value of the underlying leased assets at contract modification date. The leased assets were valued using a cost method valuation approach which utilizes Level 3 inputs. Fair Values – Reported We believe the carrying value of our other financial instruments, including cash and cash equivalents, receivables, receivables from related parties, lease receivables, lease receivables from related parties, accounts payable, and payables to related parties, approximate fair value. MPLX’s fair value assessment incorporates a variety of considerations, including the duration of the instruments, MPC’s investment-grade credit rating, and the historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. 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 prices from recent trade activity and is categorized in Level 3 of the fair value hierarchy. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs: September 30, 2022 December 31, 2021 (In millions) Fair Value Carrying Value Fair Value Carrying Value Outstanding debt (1) $ 17,552 $ 19,891 $ 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 in 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 $0.51 to $1.56 per gallon with a weighted average of $0.75 per gallon and (2) the probability of renewal of 100 percent for the five

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivatives As of September 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 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 September 30, 2022 and December 31, 2021, there were no derivative assets or liabilities that were offset in the Consolidated Balance Sheets. The impact of MPLX’s derivative contracts not designated as hedging instruments on its Consolidated Balance Sheets is summarized below: (In millions) September 30, 2022 December 31, 2021 Balance Sheet Location Asset Liability Asset Liability Commodity contracts Other current assets / Other current liabilities $ — $ 7 $ — $ 15 Other noncurrent assets / Other long-term liabilities — 39 — 93 Total $ — $ 46 $ — $ 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 in the Consolidated Statements of Income is summarized below: Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Purchased product costs Realized loss $ (2) $ (5) $ (10) $ (11) Unrealized gain / (loss) 46 (2) 62 (41) Purchased product cost derivative gain / (loss) $ 44 $ (7) $ 52 $ (52)

Debt

Debt	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Debt	Debt MPLX’s outstanding borrowings consist of the following: (In millions) September 30, December 31, MPLX LP: MPLX Credit Agreement $ — $ 300 Fixed rate senior notes 20,046 18,532 Consolidated subsidiaries: MarkWest 23 23 ANDX 31 45 Financing lease obligations 8 9 Total 20,108 18,909 Unamortized debt issuance costs (120) (102) Unamortized discount (209) (236) Amounts due within one year (982) (499) Total long-term debt due after one year $ 18,797 $ 18,072 Credit Agreement On July 7, 2022, MPLX entered into a new five-year credit agreement (the “MPLX Credit Agreement”) to replace the previous $3.5 billion credit facility that was scheduled to expire July 2024. The new MPLX Credit Agreement matures in July 2027 and, among other things, provides for a $2 billion unsecured revolving credit facility and letter of credit issuing capacity under the facility of up to $150 million. Letter of credit issuing capacity is included in, not in addition to, the $2 billion borrowing capacity. The financial covenants of the 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 MPLX Credit Agreement, plus an applicable margin. During the nine months ended September 30, 2022, MPLX borrowed $900 million under the new MPLX Credit Agreement and previous credit agreement, at an average interest rate of 1.454 percent, and repaid $1,200 million. At September 30, 2022, MPLX had no outstanding borrowings and less than $1 million in letters of credit outstanding under the new MPLX Credit Agreement, resulting in total availability of approximately $2.0 billion. Fixed Rate Senior Notes MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes maturing between 2023 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 MPC Loan Agreement and under the previous credit agreement. On August 11, 2022, MPLX issued $1.0 billion aggregate principal amount of 4.950 percent senior notes due September 2032 (the “2032 Senior Notes”) in an underwritten public offering. The 2032 Senior Notes were offered at a price to the public of 99.433 percent with interest payable semi-annually in arrears, commencing on March 1, 2023. The net proceeds were used to redeem all of the 3.500 percent senior notes due December 2022 and all of the 3.375 percent senior notes due March 2023, as discussed below. On August 25, 2022, MPLX redeemed all of the $500 million 3.500 percent senior notes due December 2022, $14 million of which was issued by Andeavor Logistics LP, at 100.1010 percent of the aggregate principal amount, plus accrued and unpaid interest to, but not including the redemption date. On September 15, 2022, MPLX redeemed all of the $500 million 3.375 percent senior notes due March 2023 at 100 percent of the aggregate principal amount. The impact of these debt extinguishments was not material to the Consolidated Statements of Income.

Revenue

Revenue	9 Months Ended
	Sep. 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 nine months ended September 30, 2022 and 2021: Three Months Ended September 30, 2022 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 94 $ 533 $ 627 Service revenue - related parties 944 4 948 Service revenue - product related — 83 83 Product sales 2 615 617 Product sales - related parties 2 44 46 Total revenues from contracts with customers $ 1,042 $ 1,279 2,321 Non-ASC 606 revenue (1) 1,080 Total revenues and other income $ 3,401 Three Months Ended September 30, 2021 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 87 $ 513 $ 600 Service revenue - related parties 896 6 902 Service revenue - product related — 82 82 Product sales 1 447 448 Product sales - related parties 2 24 26 Total revenues from contracts with customers $ 986 $ 1,072 2,058 Non-ASC 606 revenue (1) 501 Total revenues and other income $ 2,559 Nine Months Ended September 30, 2022 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 243 $ 1,515 $ 1,758 Service revenue - related parties 2,788 13 2,801 Service revenue - product related — 324 324 Product sales 5 1,807 1,812 Product sales - related parties 10 132 142 Total revenues from contracts with customers $ 3,046 $ 3,791 6,837 Non-ASC 606 revenue (1) 2,114 Total revenues and other income $ 8,951 Nine Months Ended September 30, 2021 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 262 $ 1,505 $ 1,767 Service revenue - related parties 2,666 15 2,681 Service revenue - product related — 235 235 Product sales 3 1,031 1,034 Product sales - related parties 8 91 99 Total revenues from contracts with customers $ 2,939 $ 2,877 5,816 Non-ASC 606 revenue (1) 1,477 Total revenues and other income $ 7,293 (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 in 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 nine-month periods ended September 30, 2022 and 2021: (In millions) Balance at December 31, 2021 Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 25 $ (9) $ — $ 16 Long-term contract assets 2 — — 2 Deferred revenue 56 40 (33) 63 Deferred revenue - related parties 60 79 (83) 56 Long-term deferred revenue 135 27 — 162 Long-term deferred revenue - related parties 31 (5) — 26 Long-term contract liabilities $ 5 $ (1) $ — $ 4 (In millions) Balance at December 31, 2020 Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 40 $ (21) $ 1 $ 20 Long-term contract assets 2 — — 2 Deferred revenue 37 40 (27) 50 Deferred revenue - related parties 91 59 (77) 73 Long-term deferred revenue 119 11 — 130 Long-term deferred revenue - related parties 48 (12) — 36 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 September 30, 2022, unsatisfied performance obligations included in the Consolidated Balance Sheets are $306 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 21 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 $ 497 2023 1,787 2024 1,665 2025 1,596 2026 1,427 2027 and thereafter 1,938 Total revenue on remaining performance obligations (1)(2)(3) $ 8,910 (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) Revenues classified as Rental income and Sales-type lease revenue 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.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2022
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information [Text Block]	Supplemental Cash Flow Information Nine Months Ended (In millions) 2022 2021 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 642 $ 627 Income taxes paid 2 2 Non-cash investing and financing activities: Net transfers of property, plant and equipment (to)/from materials and supplies inventories $ — $ 1 The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that do not affect cash. The following is a reconciliation of additions to property, plant and equipment to total capital expenditures: Nine Months Ended (In millions) 2022 2021 Additions to property, plant and equipment $ 535 $ 374 Increase/ (decrease) in capital accruals 39 (19) Total capital expenditures $ 574 $ 355

Leases, Codification Topic 842

Leases, Codification Topic 842	9 Months Ended
	Sep. 30, 2022
Leases [Abstract]
Leases of Lessor Disclosure [Text Block]	Leases Lease revenues included in the Consolidated Statements of Income were as follows: Three Months Ended Three Months Ended (In millions) Related Party Third Party Related Party Third Party Operating leases: Rental income $ 201 $ 75 $ 164 $ 88 Sales-type leases: Interest income (Sales-type rental revenue-fixed minimum) 114 19 132 — Interest income (Revenue from variable lease payments) 4 9 — — Sales-type lease revenue $ 118 $ 28 $ 132 $ — Nine Months Ended Nine Months Ended (In millions) Related Party Third Party Related Party Third Party Operating leases: Rental income $ 564 $ 268 $ 574 $ 286 Sales-type leases: Interest income (Sales-type rental revenue-fixed minimum) 336 19 305 — Interest income (Revenue from variable lease payments) 7 9 — — Sales-type lease revenue $ 343 $ 28 $ 305 $ — During the third quarter of 2022, the approved expansion of a gathering and compression system triggered the first assessment of the related third-party agreement under ASC 842. Similarly, an amendment to extend the term of our butane storage service agreement with MPC triggered the first assessment of the related-party agreement under ASC 842. As a result of the assessments during the period, the leases were reclassified from operating leases to sales-type leases. Accordingly, the underlying property, plant and equipment, net, and associated deferred revenue, if any, were derecognized. The present value of the future lease payments and the unguaranteed residual value of the assets were recorded as a net investment in sales-type lease during the period. 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 accounted for as sales-type leases. The following presents the consolidated financial statement impact of related-party and third-party sales-type leases, on commencement or modification date. These transactions, including any related gains recognized in the Consolidated Statements of Income, were non-cash transactions. Three Months Ended Three Months Ended (In millions) Related Party (1) Third Party (2) Related Party (1) Third Party Lease receivables $ 79 $ 914 $ — $ — Unguaranteed residual assets 6 63 — — Property, plant and equipment, net (42) (745) — — Deferred revenue — 277 — — Amount recognized on commencement date $ 43 $ 509 $ — $ — Nine Months Ended Nine Months Ended (In millions) Related Party (1) Third Party (2) Related Party (1) Third Party Lease receivables $ 79 $ 914 $ 519 $ — Unguaranteed residual assets 6 63 14 — Property, plant and equipment, net (42) (745) (421) — Deferred revenue — 277 — — Amount recognized on commencement date $ 43 $ 509 $ 112 $ — (1) The amount recognized on commencement date was recorded as a Contribution from MPC in the Consolidated Statements of Equity given the underlying agreements are between entities under common control. (2) The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income. Annual minimum undiscounted lease payment receipts under our sales-type leases were as follows as of September 30, 2022: (In millions) Related Party Third Party Total 2022 $ 119 $ 53 $ 172 2023 478 166 644 2024 479 156 635 2025 479 146 625 2026 449 136 585 2027 and thereafter 570 1,096 1,666 Total minimum future rentals 2,574 1,753 4,327 Less: present value discount 1,583 809 2,392 Lease receivables (1) 991 944 1,935 Current lease receivables (2) 102 106 208 Long-term lease receivables (3) 889 838 1,727 Unguaranteed residual assets (3) 77 63 140 Total sales-type lease assets $ 1,068 $ 1,007 $ 2,075 (1) This amount does not include the unguaranteed residual assets. (2) The related-party balance is presented in Current assets - related parties and the third-party balance is presented in Receivables, net in the Consolidated Balance Sheets. (3) The related-party balance is presented in Noncurrent assets - related parties and the third-party balance is presented in Other noncurrent assets in the Consolidated Balance Sheets.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies MPLX is the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which MPLX has not recorded 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 September 30, 2022 and December 31, 2021, accrued liabilities for remediation totaled $22 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. 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. Negotiations with the holders of the property rights at issue to settle this matter have been unsuccessful. 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. Guarantees related to indebtedness of equity method investees 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 pending completion of the EIS. The EIS has been delayed and the Army Corps currently expects to release a draft EIS in the first half of 2023. 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 September 30, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million. Contractual Commitments and Contingencies

Description of the Business a_2

Description of the Business and Basis of Presentation Accounting Policies (Policies)	9 Months Ended
	Sep. 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 These 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 nine months ended September 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 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.
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 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	These 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.

Net Income Per Limited Partne_2

Net Income Per Limited Partner Unit Accounting Policy (Policies)	9 Months Ended
	Sep. 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.

Investments and Noncontrollin_2

Investments and Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 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 September 30, September 30, December 31, (In millions, except ownership percentages) 2022 2022 2021 L&S MarEn Bakken Company LLC (1) 25% $ 485 $ 449 Illinois Extension Pipeline Company, L.L.C. 35% 247 243 LOOP LLC 41% 283 265 Andeavor Logistics Rio Pipeline LLC (2) 67% 179 183 Minnesota Pipe Line Company, LLC 17% 180 183 Whistler Pipeline LLC (2) 38% 188 155 Explorer Pipeline Company 25% 62 66 W2W Holdings LLC (2) 50% 60 58 Other (2) 148 116 Total L&S 1,832 1,718 G&P MarkWest Utica EMG, L.L.C. (2) 57% 676 680 Sherwood Midstream LLC (2) 50% 515 544 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. (2) 67% 338 332 MarkWest Torñado GP, L.L.C. (2) 60% 301 246 Rendezvous Gas Services, L.L.C. (2) 78% 139 147 Sherwood Midstream Holdings LLC (2) 51% 128 136 Centrahoma Processing LLC 40% 134 133 Other (2) 45 45 Total G&P 2,276 2,263 Total $ 4,108 $ 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.

Related Party Agreements and _2

Related Party Agreements and Transactions (Tables)	9 Months Ended
	Sep. 30, 2022
Related Party Transactions [Abstract]
Schedule of Short-term Debt	Activity on the MPC Loan Agreement was as follows: Nine Months Ended (In millions) 2022 2021 Borrowings $ 2,824 $ 6,571 Weighted average interest rate of borrowings 1.458 % 1.345 % Repayments $ 4,274 $ 5,201 Outstanding balance at end of period $ — $ 1,370
Schedule of Related Party Transactions [Table Text Block]	(In millions) September 30, December 31, Current assets - related parties Receivables $ 581 $ 555 Lease receivables 102 82 Prepaid 12 4 Other 3 3 Total 698 644 Noncurrent assets - related parties Long-term lease receivables 889 854 Right of use assets 229 229 Unguaranteed residual asset 77 47 Long-term receivables 27 31 Total 1,222 1,161 Current liabilities - related parties MPC loan agreement and other payables (1) 291 1,702 Deferred revenue - project reimbursements 38 42 Deferred revenue - minimum volume deficiencies 34 35 Operating lease liabilities 1 1 Total 364 1,780 Long-term liabilities - related parties Long-term operating lease liabilities 227 228 Long-term deferred revenue - project reimbursements 91 74 Total $ 318 $ 302 (1) Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the MPC Loan Agreement, 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 September 30, 2022.

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Schedule of Stockholders Equity [Table Text Block]	The changes in the number of common units during the nine months ended September 30, 2022 are summarized below: (In units) Common Units Balance at December 31, 2021 1,016,178,378 Unit-based compensation awards 190,529 Units redeemed in unit repurchase program (10,353,035) Balance at September 30, 2022 1,006,015,872
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 nine months ended September 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 Nine Months Ended (In millions) 2022 2021 2022 2021 Common and preferred unit distributions: Common unitholders, includes common units of general partner (1) $ 777 $ 1,305 $ 2,204 $ 2,717 Series A preferred unit distributions (1) 23 38 65 79 Series B preferred unit distributions 10 10 31 31 Total cash distributions declared $ 810 $ 1,353 $ 2,300 $ 2,827 (1) 2021 periods include the Supplemental Distribution Amount.

Net Income Per Limited Partne_3

Net Income Per Limited Partner Unit (Tables)	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Schedule of Distributions By Partner By Class [Table Text Block]	During the three and nine months ended September 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 nine months ended September 30, 2022 and 2021 were less than 1 million. Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Net income attributable to MPLX LP (1) $ 1,428 $ 802 $ 3,128 $ 2,247 Less: Distributions declared on Series A preferred units (2) 23 38 65 79 Distributions declared on Series B preferred units 10 10 31 31 Limited partners’ distributions declared on MPLX common units (including common units of general partner) (2) 777 1,305 2,204 2,717 Undistributed net gain/ (loss) attributable to MPLX LP $ 618 $ (551) $ 828 $ (580) (1) The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information. (2) 2021 periods include the Supplemental Distribution Amount.
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended September 30, 2022 (In millions, except per unit data) Limited Partners’ 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 $ 777 $ 23 $ 10 $ 810 Undistributed net gain attributable to MPLX LP (1) 600 $ 18 — 618 Net income attributable to MPLX LP (2) $ 1,377 $ 41 $ 10 $ 1,428 Weighted average units outstanding: Basic 1,010 Diluted 1,011 Net income attributable to MPLX LP per limited partner unit: Basic $ 1.36 Diluted $ 1.36 (1) The undistributed net gain attributable to MPLX LP includes a $509 million non-cash gain on a lease reclassification for the three months ended September 30, 2022. See Note 14 for additional information. (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. Three Months Ended September 30, 2021 (In millions, except per unit data) Limited Partners’ 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) $ 1,305 $ 38 $ 10 $ 1,353 Undistributed net loss attributable to MPLX LP (551) — — (551) Net income attributable to MPLX LP (2) $ 754 $ 38 $ 10 $ 802 Weighted average units outstanding: Basic 1,024 Diluted 1,025 Net income attributable to MPLX LP per limited partner unit: Basic $ 0.74 Diluted $ 0.74 (1) Includes the Supplemental Distribution Amount. (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. Nine Months Ended September 30, 2022 (In millions, except per unit data) Limited Partners’ 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 $ 2,204 $ 65 $ 31 $ 2,300 Undistributed net gain attributable to MPLX LP (1) 804 24 — 828 Net income attributable to MPLX LP (2) $ 3,008 $ 89 $ 31 $ 3,128 Weighted average units outstanding: Basic 1,012 Diluted 1,013 Net income attributable to MPLX LP per limited partner unit: Basic $ 2.97 Diluted $ 2.97 (1) The undistributed net gain attributable to MPLX LP includes a $509 million non-cash gain on a lease reclassification for the nine months ended September 30, 2022. See Note 14 for additional information. (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. Nine Months Ended September 30, 2021 (In millions, except per unit data) Limited Partners’ 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) $ 2,717 $ 79 $ 31 $ 2,827 Undistributed net loss attributable to MPLX LP (580) — — (580) Net income attributable to MPLX LP (2) $ 2,137 $ 79 $ 31 $ 2,247 Weighted average units outstanding: Basic 1,030 Diluted 1,030 Net income attributable to MPLX LP per limited partner unit: Basic $ 2.07 Diluted $ 2.07 (1) Includes the Supplemental Distribution Amount. (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.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 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 Nine Months Ended (In millions) 2022 2021 2022 2021 L&S Service revenue $ 1,038 $ 983 $ 3,031 $ 2,928 Rental income 210 172 593 597 Product related revenue 4 3 15 11 Sales-type lease revenue 118 132 343 305 Income from equity method investments 72 41 183 112 Other income 8 15 42 46 Total segment revenues and other income (1) 1,450 1,346 4,207 3,999 Segment Adjusted EBITDA (2) 969 904 2,839 2,747 Capital expenditures 80 85 238 220 Investments in unconsolidated affiliates 12 9 90 31 G&P Service revenue 537 519 1,528 1,520 Rental income 66 80 239 263 Product related revenue 742 553 2,263 1,357 Sales-type lease revenue 28 — 28 — Income from equity method investments 53 51 152 116 Other income (3) 525 10 534 38 Total segment revenues and other income (1) 1,951 1,213 4,744 3,294 Segment Adjusted EBITDA (2) 502 485 1,482 1,368 Capital expenditures 146 69 336 135 Investments in unconsolidated affiliates $ 30 $ 23 $ 108 $ 85 (1) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $175 million and $468 million for the three and nine months ended September 30, 2022, respectively, and $138 million and $405 million for the three and nine months ended September 30, 2021, respectively. Third party revenues for the G&P segment were $1,885 million and $4,551 million for the three and nine months ended September 30, 2022, respectively, and $1,170 million and $3,147 million for the three and nine months ended September 30, 2021, respectively. (2) See below for the reconciliation from Segment Adjusted EBITDA to Net income. (3) The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information.
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 Nine Months Ended (In millions) 2022 2021 2022 2021 Reconciliation to Net income: L&S Segment Adjusted EBITDA $ 969 $ 904 $ 2,839 $ 2,747 G&P Segment Adjusted EBITDA 502 485 1,482 1,368 Total reportable segments 1,471 1,389 4,321 4,115 Depreciation and amortization (1) (302) (324) (925) (971) Gain on sales-type leases 509 — 509 — Impairment expense — — — (42) Interest and other financial costs (236) (220) (691) (661) Income from equity method investments 125 92 335 228 Distributions/adjustments related to equity method investments (166) (129) (450) (371) Other (2) 26 (6) 26 (53) Adjusted EBITDA attributable to noncontrolling interests 10 9 29 29 Net income $ 1,437 $ 811 $ 3,154 $ 2,274 (1) Depreciation and amortization attributable to L&S was $128 million and $387 million for the three and nine months ended September 30, 2022, respectively, and $131 million and $414 million for the three and nine months ended September 30, 2021, respectively. Depreciation and amortization attributable to G&P was $174 million and $538 million for the three and nine months ended September 30, 2022, respectively, and $193 million and $557 million for the three and nine months ended September 30, 2021, respectively.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment	Property, plant and equipment with associated accumulated depreciation is shown below: September 30, 2022 December 31, 2021 (In millions) Gross PP&E Accumulated Depreciation Net PP&E Gross PP&E Accumulated Depreciation Net PP&E L&S $ 12,373 $ 3,456 $ 8,917 $ 12,371 $ 3,227 $ 9,144 G&P 13,389 3,396 9,993 14,175 3,277 10,898 Total $ 25,762 $ 6,852 $ 18,910 $ 26,546 $ 6,504 $ 20,042

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 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 liabilities classified as Level 3 in the fair value hierarchy. Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Beginning balance $ (92) $ (102) $ (108) $ (63) Unrealized and realized gain/ (loss) included in net income (1) 44 (7) 52 (52) Settlements 2 5 10 11 Ending balance (46) (104) (46) (104) 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 $ 42 $ (6) $ 50 $ (44) (1) Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs in 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: September 30, 2022 December 31, 2021 (In millions) Fair Value Carrying Value Fair Value Carrying Value Outstanding debt (1) $ 17,552 $ 19,891 $ 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 in the Consolidated Balance Sheets.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 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 contracts not designated as hedging instruments on its Consolidated Balance Sheets is summarized below: (In millions) September 30, 2022 December 31, 2021 Balance Sheet Location Asset Liability Asset Liability Commodity contracts Other current assets / Other current liabilities $ — $ 7 $ — $ 15 Other noncurrent assets / Other long-term liabilities — 39 — 93 Total $ — $ 46 $ — $ 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 in the Consolidated Statements of Income is summarized below: Three Months Ended Nine Months Ended (In millions) 2022 2021 2022 2021 Purchased product costs Realized loss $ (2) $ (5) $ (10) $ (11) Unrealized gain / (loss) 46 (2) 62 (41) Purchased product cost derivative gain / (loss) $ 44 $ (7) $ 52 $ (52)

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	MPLX’s outstanding borrowings consist of the following: (In millions) September 30, December 31, MPLX LP: MPLX Credit Agreement $ — $ 300 Fixed rate senior notes 20,046 18,532 Consolidated subsidiaries: MarkWest 23 23 ANDX 31 45 Financing lease obligations 8 9 Total 20,108 18,909 Unamortized debt issuance costs (120) (102) Unamortized discount (209) (236) Amounts due within one year (982) (499) Total long-term debt due after one year $ 18,797 $ 18,072

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 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 nine months ended September 30, 2022 and 2021: Three Months Ended September 30, 2022 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 94 $ 533 $ 627 Service revenue - related parties 944 4 948 Service revenue - product related — 83 83 Product sales 2 615 617 Product sales - related parties 2 44 46 Total revenues from contracts with customers $ 1,042 $ 1,279 2,321 Non-ASC 606 revenue (1) 1,080 Total revenues and other income $ 3,401 Three Months Ended September 30, 2021 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 87 $ 513 $ 600 Service revenue - related parties 896 6 902 Service revenue - product related — 82 82 Product sales 1 447 448 Product sales - related parties 2 24 26 Total revenues from contracts with customers $ 986 $ 1,072 2,058 Non-ASC 606 revenue (1) 501 Total revenues and other income $ 2,559 Nine Months Ended September 30, 2022 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 243 $ 1,515 $ 1,758 Service revenue - related parties 2,788 13 2,801 Service revenue - product related — 324 324 Product sales 5 1,807 1,812 Product sales - related parties 10 132 142 Total revenues from contracts with customers $ 3,046 $ 3,791 6,837 Non-ASC 606 revenue (1) 2,114 Total revenues and other income $ 8,951 Nine Months Ended September 30, 2021 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 262 $ 1,505 $ 1,767 Service revenue - related parties 2,666 15 2,681 Service revenue - product related — 235 235 Product sales 3 1,031 1,034 Product sales - related parties 8 91 99 Total revenues from contracts with customers $ 2,939 $ 2,877 5,816 Non-ASC 606 revenue (1) 1,477 Total revenues and other income $ 7,293
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 nine-month periods ended September 30, 2022 and 2021: (In millions) Balance at December 31, 2021 Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 25 $ (9) $ — $ 16 Long-term contract assets 2 — — 2 Deferred revenue 56 40 (33) 63 Deferred revenue - related parties 60 79 (83) 56 Long-term deferred revenue 135 27 — 162 Long-term deferred revenue - related parties 31 (5) — 26 Long-term contract liabilities $ 5 $ (1) $ — $ 4 (In millions) Balance at December 31, 2020 Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 40 $ (21) $ 1 $ 20 Long-term contract assets 2 — — 2 Deferred revenue 37 40 (27) 50 Deferred revenue - related parties 91 59 (77) 73 Long-term deferred revenue 119 11 — 130 Long-term deferred revenue - related parties 48 (12) — 36 Long-term contract liabilities $ 6 $ — $ — $ 6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	As of September 30, 2022, unsatisfied performance obligations included in the Consolidated Balance Sheets are $306 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 21 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 $ 497 2023 1,787 2024 1,665 2025 1,596 2026 1,427 2027 and thereafter 1,938 Total revenue on remaining performance obligations (1)(2)(3) $ 8,910 (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) Revenues classified as Rental income and Sales-type lease revenue 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.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2022
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information [Table Text Block]	Nine Months Ended (In millions) 2022 2021 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 642 $ 627 Income taxes paid 2 2 Non-cash investing and financing activities: Net transfers of property, plant and equipment (to)/from materials and supplies inventories $ — $ 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 a reconciliation of additions to property, plant and equipment to total capital expenditures: Nine Months Ended (In millions) 2022 2021 Additions to property, plant and equipment $ 535 $ 374 Increase/ (decrease) in capital accruals 39 (19) Total capital expenditures $ 574 $ 355

Leases, Codification Topic 842

Leases, Codification Topic 842 (Tables)	9 Months Ended
	Sep. 30, 2022
Leases [Abstract]
Sales-type Lease, Lease Income [Table Text Block]	Lease revenues included in the Consolidated Statements of Income were as follows: Three Months Ended Three Months Ended (In millions) Related Party Third Party Related Party Third Party Operating leases: Rental income $ 201 $ 75 $ 164 $ 88 Sales-type leases: Interest income (Sales-type rental revenue-fixed minimum) 114 19 132 — Interest income (Revenue from variable lease payments) 4 9 — — Sales-type lease revenue $ 118 $ 28 $ 132 $ — Nine Months Ended Nine Months Ended (In millions) Related Party Third Party Related Party Third Party Operating leases: Rental income $ 564 $ 268 $ 574 $ 286 Sales-type leases: Interest income (Sales-type rental revenue-fixed minimum) 336 19 305 — Interest income (Revenue from variable lease payments) 7 9 — — Sales-type lease revenue $ 343 $ 28 $ 305 $ —
Operating Lease, Lease Income [Table Text Block]	Lease revenues included in the Consolidated Statements of Income were as follows: Three Months Ended Three Months Ended (In millions) Related Party Third Party Related Party Third Party Operating leases: Rental income $ 201 $ 75 $ 164 $ 88 Sales-type leases: Interest income (Sales-type rental revenue-fixed minimum) 114 19 132 — Interest income (Revenue from variable lease payments) 4 9 — — Sales-type lease revenue $ 118 $ 28 $ 132 $ — Nine Months Ended Nine Months Ended (In millions) Related Party Third Party Related Party Third Party Operating leases: Rental income $ 564 $ 268 $ 574 $ 286 Sales-type leases: Interest income (Sales-type rental revenue-fixed minimum) 336 19 305 — Interest income (Revenue from variable lease payments) 7 9 — — Sales-type lease revenue $ 343 $ 28 $ 305 $ —
Sales-type and Direct Financing Leases, Lease Receivable, Maturity [Table Text Block]	Annual minimum undiscounted lease payment receipts under our sales-type leases were as follows as of September 30, 2022: (In millions) Related Party Third Party Total 2022 $ 119 $ 53 $ 172 2023 478 166 644 2024 479 156 635 2025 479 146 625 2026 449 136 585 2027 and thereafter 570 1,096 1,666 Total minimum future rentals 2,574 1,753 4,327 Less: present value discount 1,583 809 2,392 Lease receivables (1) 991 944 1,935 Current lease receivables (2) 102 106 208 Long-term lease receivables (3) 889 838 1,727 Unguaranteed residual assets (3) 77 63 140 Total sales-type lease assets $ 1,068 $ 1,007 $ 2,075 (1) This amount does not include the unguaranteed residual assets. (2) The related-party balance is presented in Current assets - related parties and the third-party balance is presented in Receivables, net in the Consolidated Balance Sheets.

Description of Business and Bas

Description of Business and Basis of Presentation - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Number of reportable segments	2

Investments and Noncontrollin_3

Investments and Noncontrolling Interests (Summary of Equity Method Investment Financial Information) (Details) - USD ($) $ in Millions		Sep. 30, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 4,108	$ 3,981
MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25%
Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35%
LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41%
Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67%
Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17%
Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38%
Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25%
W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57%
Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50%
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67%
MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		60%
Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		78%
Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40%
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		9.19%
Indirect Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.55%
Direct Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		51%
G&P | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	$ 676	680
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	515	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]	338	332
G&P | MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	301	246
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	139	147
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	128	136
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		134	133
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	45	45
L&S | MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	485	449
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		247	243
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		283	265
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	179	183
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		180	183
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	188	155
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		62	66
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	60	58
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	148	116
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Equity method investments		2,276	2,263
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 1,832	$ 1,718
[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.

Related Party Agreements and _3

Related Party Agreements and Transactions MPC Loan Agreement (Details) - Related Party Revolving Credit Agreement [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Related party debt - borrowings	$ 2,824	$ 6,571
Repayments of Related Party Debt	4,274	$ 5,201
MPC Investment [Member]
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
Line of Credit Facility, Interest Rate During Period	1.458%	1.345%
Line of Credit, Current	$ 0	$ 1,370	$ 1,450

Related Party Disclosures (Deta

Related Party Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Asset and Inventory transfers
Related Party Transaction [Line Items]
Revenue from Related Parties			$ 20	$ 19
Related Party Transaction, Purchases from Related Party			31
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Sales Revenue, Goods, Related Party, Net Zero	$ 235	$ 203	809	548
Marathon Petroleum Corporation [Member] | Asset under Construction [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 16	$ 13	$ 54	$ 40

Summary of Charges for Employee

Summary of Charges for Employee Services and Omnibus Agreements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Related Party Transaction [Line Items]
General and Administrative Expense	$ 88	$ 94	$ 248	$ 267
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
General and Administrative Expense	60	70	173	190
Asset under Construction [Member] | Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 16	$ 13	$ 54	$ 40

Other Assets and Liabilities fr

Other Assets and Liabilities from Related Parties (Details) - USD ($) $ in Millions		Sep. 30, 2022		Aug. 01, 2022	Jul. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Apr. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Net Investment in Lease, before Allowance for Credit Loss, Current	[1]	$ 208
Net Investment in Lease, Noncurrent	[2]	1,727
Sales-type Lease, Unguaranteed Residual Asset	[2]	140
Due from Related Parties, Noncurrent		1,222				$ 1,161
Long-term deferred revenue		170				383	$ 0
Third Party [Member]
Related Party Transaction [Line Items]
Net Investment in Lease, before Allowance for Credit Loss, Current	[1]	106
Net Investment in Lease, Noncurrent	[2]	838
Sales-type Lease, Unguaranteed Residual Asset		63	[2]		$ 63		0
Deferred Revenue, Current		63				56	50		$ 37
Long-term deferred revenue					$ 277		0
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Net Investment in Lease, before Allowance for Credit Loss, Current	[1]	102
Net Investment in Lease, Noncurrent	[2]	889
Sales-type Lease, Unguaranteed Residual Asset	[2]	77
Affiliated Entity
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties, Current		581				555
Prepaid Expense, Current		12				4
Other Assets, Current, Related Parties		3				3
Net Investment in Lease, before Allowance for Credit Loss, Current		102				82
Current Assets, Related Parties		698				644
Accounts Receivable, Related Parties, Noncurrent		27				31
Net Investment in Lease, Noncurrent		889				854
Operating Lease, Right-of-Use Asset, Related Party		229				229
Sales-type Lease, Unguaranteed Residual Asset		77		$ 6		47	0	$ 14
Accounts Payable, Related Parties, Current	[3]	291				1,702
Deferred Revenue, Current		56				60	73		$ 91
Operating Lease, Liability, Current		1				1
Operating Lease, Liability, Noncurrent		227				228
Due to Related Parties, Current		364				1,780
Long-term deferred revenue				$ 0				$ 0
Liabilities, Related Parties, Noncurrent		318				302
MPC Investment [Member] | Related Party Revolving Credit Agreement [Member]
Related Party Transaction [Line Items]
Line of Credit, Current		0				1,450	$ 1,370
Minimum Committed Volume Contracts [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Deferred Revenue, Current		34				35
Reimbursable Projects [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Deferred Revenue, Current		38				42
Long-term deferred revenue		$ 91				$ 74
[1]The related-party balance is presented in Current assets - related parties and the third-party balance is presented in Receivables, net in the Consolidated Balance Sheets.[2]The related-party balance is presented in Noncurrent assets - related parties and the third-party balance is presented in Other noncurrent assets in the Consolidated Balance Sheets.[3]Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the MPC Loan Agreement, 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 September 30, 2022.

Equity - Changes in Partners Ca

Equity - Changes in Partners Capital, Unit Rollforward (Details) - USD ($) $ / shares in Units, $ in Millions											3 Months Ended							9 Months Ended			11 Months Ended
	Nov. 01, 2022	Oct. 04, 2022	Aug. 15, 2022	Jul. 26, 2022	Apr. 26, 2022	Feb. 15, 2022	Oct. 26, 2021	[2]	Jul. 27, 2021	Apr. 27, 2021	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021		Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 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											$ (744)	$ (724)	$ (746)	$ (735)		$ (717)	$ (745)
Distribution Made to Limited Partner, Cash Distributions Declared											$ 810			$ 1,353	[1]			$ 2,300	$ 2,827	[1]
Stock Repurchase Program, Authorized Amount																						$ 1,000		$ 1,000
Treasury Stock Acquired, Average Cost Per Share											$ 31.65			$ 28.41				$ 31.98	$ 26.79
Stock Repurchase Program, Remaining Authorized Repurchase Amount											$ 1,006							$ 1,006
Cash distributions declared per limited partner common unit				$ 0.7050	$ 0.7050		$ 1.2800		$ 0.6875	$ 0.6875
Payments for Repurchase of Common Stock											$ 180			$ 155				$ 315	$ 465
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																		190,529
Stock Repurchased and Retired During Period, Shares											6,000,000			6,000,000				10,353,035	18,000,000
Balance at September 30, 2022											1,006,015,872							1,006,015,872
Distribution Made to Limited Partner, Cash Distributions Declared											$ 777			$ 1,305	[1],[2]			$ 2,204	$ 2,717	[1]
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											$ (20)	$ 0	$ (21)	(20)		$ 0	$ (21)
Subsequent Event
Stockholders Equity [Line Items]
Cash distributions declared per limited partner common unit	$ 0.7750
Payments for Repurchase of Common Stock		$ 16
Subsequent Event | Limited Partners Common Units [Member]
Stockholders Equity [Line Items]
Stock Repurchased and Retired During Period, Shares		532,326
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
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders			$ (21)			$ (21)
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				$ 31	$ 31
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
[1]2021 periods include the Supplemental Distribution Amount.[2]Includes a supplemental distribution amount of $0.575 per common unit declared and paid during the fourth quarter of 2021 (the “Supplemental Distribution Amount”)

Equity - Cash Distributions (De

Equity - Cash Distributions (Details) - USD ($) $ / shares in Units, $ in Millions

3 Months Ended

9 Months Ended

11 Months Ended

Nov. 22, 2022

Nov. 15, 2022

Nov. 01, 2022

Aug. 15, 2022

Jul. 26, 2022

Apr. 26, 2022

Feb. 15, 2022

Oct. 26, 2021

Jul. 27, 2021

Apr. 27, 2021

Sep. 30, 2022

Jun. 30, 2022

Mar. 31, 2022

Sep. 30, 2021

Jun. 30, 2021

Mar. 31, 2021

Sep. 30, 2022

Sep. 30, 2021

Dec. 31, 2023

Incentive Distribution Made to Managing Member or General Partner [Line Items]

Distribution Made to Limited Partner, Cash Distributions Declared

$ 810

$ 1,353

[1]

$ 2,300

$ 2,827

[1]

Cash distributions declared per limited partner common unit

$ 0.7050

$ 0.7050

$ 1.2800

[2]

$ 0.6875

$ 0.6875

Partners' Capital Account, Distributions

$ 744

$ 724

$ 746

735

$ 717

$ 745

Supplemental distribution

Incentive Distribution Made to Managing Member or General Partner [Line Items]

Cash distributions declared per limited partner common unit

$ 0.575

Series B Preferred Stock [Member]

Incentive Distribution Made to Managing Member or General Partner [Line Items]

Preferred Units, Outstanding

600,000

600,000

Distribution date

Aug. 15, 2022

Feb. 15, 2022

Partners' Capital Account, Distributions

$ 21

$ 21

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

Nov. 01, 2022

Cash distributions declared per limited partner common unit

$ 0.7750

Distribution date

Nov. 22, 2022

Date of record

Nov. 15, 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

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

$ 777

1,305

[1],[2]

$ 2,204

2,717

[1]

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

23

38

[1],[2]

65

79

[1],[2]

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

$ 31

$ 31

Cash distributions declared per limited partner common unit

$ 68.75

[1]2021 periods include the Supplemental Distribution Amount.[2]Includes a supplemental distribution amount of $0.575 per common unit declared and paid during the fourth quarter of 2021 (the “Supplemental Distribution Amount”)

Net Income Per Limited Partne_4

Net Income Per Limited Partner Unit - Schedule of Distributions by Partner by Class (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021		Sep. 30, 2022		Sep. 30, 2021
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	$ 1,428	[2]	$ 802		$ 3,128	[2]	$ 2,247
Distribution Made to Limited Partner, Cash Distributions Declared		810		1,353	[3]	2,300		2,827	[3]
Undistributed net income (loss) attributable to MPLX LP		618	[2]	(551)		828	[2]	(580)
Limited Partners Common Units [Member]
Net Income Per Share [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		777		1,305	[3],[4]	2,204		2,717	[3]
Undistributed net income (loss) attributable to MPLX LP		600	[2]	(551)		804	[2]	(580)
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	41	[2]	38		89	[2]	79
Distribution Made to Limited Partner, Cash Distributions Declared		23		38	[3],[4]	65		79	[3],[4]
Undistributed net income (loss) attributable to MPLX LP		18	[2]	0		24	[2]	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	[2]	10		31	[2]	31
Distribution Made to Limited Partner, Cash Distributions Declared		10		10		31		31
Undistributed net income (loss) attributable to MPLX LP		0	[2]	0		0	[2]	0
Common Stock | Limited Partners Common Units [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	$ 1,377	[2]	$ 754		$ 3,008	[2]	$ 2,137
[1]Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.[2]The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information.[3]2021 periods include the Supplemental Distribution Amount.[4]Includes a supplemental distribution amount of $0.575 per common unit declared and paid during the fourth quarter of 2021 (the “Supplemental Distribution Amount”)

Net Income Per Limited Partne_5

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				9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021		Sep. 30, 2022		Sep. 30, 2021
Weighted average units outstanding:
Common - basic (in shares)		1,010		1,024		1,012		1,030
Common - diluted (in shares)		1,011		1,025		1,013		1,030
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax		$ 1.36		$ 0.74		$ 2.97		$ 2.07
Common - diluted (in USD per unit)		$ 1.36		$ 0.74		$ 2.97		$ 2.07
Distribution Made to Limited Partner, Cash Distributions Declared		$ 810		$ 1,353	[1]	$ 2,300		$ 2,827	[1]
Undistributed net income (loss) attributable to MPLX LP		618	[2]	(551)		828	[2]	(580)
Net Income (Loss) Attributable to Parent	[3]	$ 1,428	[2]	$ 802		$ 3,128	[2]	$ 2,247
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		$ 777		$ 1,305	[1],[4]	$ 2,204		$ 2,717	[1]
Undistributed net income (loss) attributable to MPLX LP		600	[2]	(551)		804	[2]	(580)
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Weighted average units outstanding:
Distribution Made to Limited Partner, Cash Distributions Declared		23		38	[1],[4]	65		79	[1],[4]
Undistributed net income (loss) attributable to MPLX LP		18	[2]	0		24	[2]	0
Net Income (Loss) Attributable to Parent	[3]	41	[2]	38		89	[2]	79
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Weighted average units outstanding:
Distribution Made to Limited Partner, Cash Distributions Declared		10		10		31		31
Undistributed net income (loss) attributable to MPLX LP		0	[2]	0		0	[2]	0
Net Income (Loss) Attributable to Parent	[3]	10	[2]	10		31	[2]	31
Common Stock | Limited Partners Common Units [Member]
Weighted average units outstanding:
Net Income (Loss) Attributable to Parent	[3]	$ 1,377	[2]	$ 754		$ 3,008	[2]	$ 2,137
[1]2021 periods include the Supplemental Distribution Amount.[2]The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information.[3]Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.[4]Includes a supplemental distribution amount of $0.575 per common unit declared and paid during the fourth quarter of 2021 (the “Supplemental Distribution Amount”)

Segment Information (Details)

Segment Information (Details)	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information - Segment A

Segment Information - Segment Adjusted EBITDA (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021	Sep. 30, 2022		Sep. 30, 2021
Segment Reporting Information [Line Items]
Sales-type lease revenue, related parties		$ 118		$ 132	$ 343		$ 305
Operating Lease, Lease Income		75		88	268		286
Sales-type Lease, Revenue		28		0	28		0
Income from equity method investments		125		92	335		228
Total segment revenues and other income		(3,401)		(2,559)	(8,951)		(7,293)
Payments to Acquire Equity Method Investments					(198)		(116)
Sales-type Lease, Selling Profit (Loss)		509		0	509		0
L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,042		986	3,046		2,939
G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,279		1,072	3,791		2,877
Operating Segments
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		2,321		2,058	6,837		5,816
Adjusted EBITDA		1,471		1,389	4,321		4,115
Operating Segments | L&S
Segment Reporting Information [Line Items]
Sales-type lease revenue, related parties		118		132	343		305
Operating Lease, Lease Income		210		172	593		597
Income from equity method investments		72		41	183		112
Other income		8		15	42		46
Total segment revenues and other income	[1]	(1,450)		(1,346)	(4,207)		(3,999)
Adjusted EBITDA	[2]	969		904	2,839		2,747
Capital Expenditure		80		85	238		220
Payments to Acquire Equity Method Investments		(12)		(9)	(90)		(31)
Operating Segments | G&P
Segment Reporting Information [Line Items]
Operating Lease, Lease Income		66		80	239		263
Sales-type Lease, Revenue		28		0	28		0
Income from equity method investments		53		51	152		116
Other income		525	[3]	10	534	[3]	38
Total segment revenues and other income	[1]	(1,951)		(1,213)	(4,744)		(3,294)
Adjusted EBITDA	[2]	502		485	1,482		1,368
Capital Expenditure		146		69	336		135
Payments to Acquire Equity Method Investments		(30)		(23)	(108)		(85)
Service [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		627		600	1,758		1,767
Service [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,038		983	3,031		2,928
Service [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		537		519	1,528		1,520
Product [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		617		448	1,812		1,034
Product [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		4		3	15		11
Product [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		742		553	2,263		1,357
Third Party [Member] | L&S
Segment Reporting Information [Line Items]
Total segment revenues and other income		(175)		(138)	(468)		(405)
Third Party [Member] | G&P
Segment Reporting Information [Line Items]
Total segment revenues and other income		$ (1,885)		$ (1,170)	$ (4,551)		$ (3,147)
[1]Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $175 million and $468 million for the three and nine months ended September 30, 2022, respectively, and $138 million and $405 million for the three and nine months ended September 30, 2021, respectively. Third party revenues for the G&P segment were $1,885 million and $4,551 million for the three and nine months ended September 30, 2022, respectively, and $1,170 million and $3,147 million for the three and nine months ended September 30, 2021, respectively.[2]See below for the reconciliation from Segment Adjusted EBITDA to Net income.[3]The three and nine months ended September 30, 2022 include a $509 million non-cash gain on a lease reclassification. See Note 14 for additional information.

Segment Information - Reconcili

Segment Information - Reconciliation to Net Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization	[1]	$ (302)	$ (324)	$ (925)	$ (971)
Sales-type Lease, Selling Profit (Loss)		509	0	509	0
Asset Impairment Charges		0	0	0	42
Income from equity method investments		125	92	335	228
Proceeds from Equity Method Investment, Distribution				(405)	(361)
Net income		1,437	811	3,154	2,274
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA		1,471	1,389	4,321	4,115
Segment Reconciling Items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Interest and Other Financial Costs		(236)	(220)	(691)	(661)
Proceeds from Equity Method Investment, Distribution		(166)	(129)	(450)	(371)
Other Cost and Expense, Operating		26	(6)	26	(53)
Adjusted EBITDA attributable to noncontrolling interests		10	9	29	29
L&S
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization		(128)	(131)	(387)	(414)
L&S | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[2]	969	904	2,839	2,747
Income from equity method investments		72	41	183	112
G&P
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization		(174)	(193)	(538)	(557)
G&P | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[2]	502	485	1,482	1,368
Income from equity method investments		$ 53	$ 51	$ 152	$ 116
[1]Depreciation and amortization attributable to L&S was $128 million and $387 million for the three and nine months ended September 30, 2022, respectively, and $131 million and $414 million for the three and nine months ended September 30, 2021, respectively. Depreciation and amortization attributable to G&P was $174 million and $538 million for the three and nine months ended September 30, 2022, respectively, and $193 million and $557 million for the three and nine months ended September 30, 2021, respectively. (2)    Includes unrealized derivative gain/ (loss), non-cash equity-based compensation, and other miscellaneous items.[2]See below for the reconciliation from Segment Adjusted EBITDA to Net income.

Property, Plant and Equipment_2

Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 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	$ 25,762		$ 25,762		$ 26,546
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization	6,852		6,852		6,504
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	18,910		18,910		20,042
Asset Impairment Charges	0	$ 0	0	$ 42
Interest Costs Capitalized	2	$ 2	7	$ 12
L&S
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	12,373		12,373		12,371
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization	3,456		3,456		3,227
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	8,917		8,917		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	13,389		13,389		14,175
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization	3,396		3,396		3,277
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	$ 9,993		$ 9,993		$ 10,898

Fair Value Measurements - Recur

Fair Value Measurements - Recurring - Financial Instruments by Valuation Hierarchy (Details) - USD ($) $ in Millions	Sep. 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	(46)	(108)
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	$ 46	$ 108

Fair Value Measurments - Recurr

Fair Value Measurments - Recurring - Significant Unobservable Inputs in Level 3 Valuation (Details)	9 Months Ended
	Sep. 30, 2022 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.75
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%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Forward Price	0.51
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Forward Price	1.56

Fair Value Measurements - Rec_2

Fair Value Measurements - Recurring - Changes in Level 3 Measurements (Details) - Embedded Derivatives in Commodity Contracts (net) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value at beginning of period		$ (92)	$ (102)	$ (108)	$ (63)
Total gains (losses) (realized and unrealized) included in earnings	[1]	44	(7)	52	(52)
Settlements		2	5	10	11
Fair value at end of period		(46)	(104)	(46)	(104)
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		$ 42	$ (6)	$ 50	$ (44)
[1]Gain/ (loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs in the Consolidated Statements of Income.

Fair Value Measurements - Repor

Fair Value Measurements - Reported (Details) - USD ($) $ in Millions		Sep. 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]	$ 19,891	$ 18,664
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	[1]	$ 17,552	$ 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 in the Consolidated Balance Sheets.

Derivative Financial Instrume_3

Derivative Financial Instruments - Embedded Derivatives in Commodity Contracts (Details) - Embedded Derivative Financial Instruments [Member] $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Liability	$ (46)	$ (108)
Natural Gas [Member]
Derivative [Line Items]
Number of Renewals	1
Embedded Derivative Renewal Term	5 years

Derivative Financial Instrume_4

Derivative Financial Instruments - Derivatives Balance Sheet Location (Details) - Not Designated as Hedging Instrument [Member] - Commodity Contract [Member] - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	46	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	7	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	$ 39	$ 93

Derivatives Financial Instrumen

Derivatives Financial Instruments - Derivative Income Statement Location (Details) - Purchased product costs - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Derivative [Line Items]
Realized gain (loss)	$ (2)	$ (5)	$ (10)	$ (11)
Total gain (loss)	44	(7)	52	(52)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ 46	$ (2)	$ 62	$ (41)

Debt - Summary of Outstanding B

Debt - Summary of Outstanding Borrowings (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Aug. 25, 2022	Mar. 14, 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	(120)			(102)
Unamortized discount	(209)			(236)
Long-term Debt and Lease Obligation, Current	982			499
Total long-term debt due after one year	18,797			18,072
MPLX LP [Member]
Debt Instrument [Line Items]
Senior Notes	20,046			18,532
MarkWest [Member]
Debt Instrument [Line Items]
Senior Notes	23			23
ANDX LP [Member]
Debt Instrument [Line Items]
Senior Notes	$ 31			$ 45
Senior Note Due March 2052 [Domain] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.95%
Percent of Par			98.982%
Senior Notes Due December 2022 | Senior Notes [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.50%
Percent of Par		10,010.10%

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($) $ in Millions				9 Months Ended
	Aug. 11, 2022	Jul. 07, 2022	Mar. 14, 2022	Sep. 30, 2022	Sep. 15, 2022	Aug. 25, 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				120			102
Debt Instrument, Unamortized Discount				209			236
Long-term debt				18,797			$ 18,072
MPLX Revolving Credit Facility due June 2027
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 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				2,000
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
Senior Notes [Member] | Senior Note Due September 2032
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.95%
Percent of Par	99.433%
Debt Instrument, Face Amount	$ 1,000
Debt Instrument, Issuance Date	Aug. 11, 2022
Senior Notes [Member] | Senior Notes Due December 2022
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 500
Senior Notes [Member] | Senior Notes Due December 2022 | MPLX LP [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						3.50%
Percent of Par						10,010.10%
Senior Notes [Member] | Senior Notes Due December 2022 | ANDX LP [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 14
Senior Notes [Member] | Senior Notes Due March 2023
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 500
Senior Notes [Member] | Senior Notes Due March 2023 | MPLX LP [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					3.375%
Percent of Par					10,000%
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%

Revenue Disaggregation of Reven

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 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]	$ 1,080	$ 501	$ 2,114	$ 1,477
Revenues		3,401	2,559	8,951	7,293
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,321	2,058	6,837	5,816
L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,042	$ 986	$ 3,046	$ 2,939
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]	$ 1,450	$ 1,346	$ 4,207	$ 3,999
G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,279	$ 1,072	$ 3,791	$ 2,877
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]	$ 1,951	$ 1,213	$ 4,744	$ 3,294
Service [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		627	600	1,758	1,767
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		948	902	2,801	2,681
Service [Member] | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		627	600	1,758	1,767
Service [Member] | L&S
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		944	896	2,788	2,666
Service [Member] | L&S | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		94	87	243	262
Service [Member] | L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1,038	983	3,031	2,928
Service [Member] | G&P
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		4	6	13	15
Service [Member] | G&P | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		533	513	1,515	1,505
Service [Member] | G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		537	519	1,528	1,520
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		83	82	324	235
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		83	82	324	235
Product [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		617	448	1,812	1,034
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		46	26	142	99
Product [Member] | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		617	448	1,812	1,034
Product [Member] | L&S
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		2	2	10	8
Product [Member] | L&S | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2	1	5	3
Product [Member] | L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		4	3	15	11
Product [Member] | G&P
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		44	24	132	91
Product [Member] | G&P | Third Party [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		615	447	1,807	1,031
Product [Member] | G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 742	$ 553	$ 2,263	$ 1,357
[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 $175 million and $468 million for the three and nine months ended September 30, 2022, respectively, and $138 million and $405 million for the three and nine months ended September 30, 2021, respectively. Third party revenues for the G&P segment were $1,885 million and $4,551 million for the three and nine months ended September 30, 2022, respectively, and $1,170 million and $3,147 million for the three and nine months ended September 30, 2021, respectively.

Revenue Contract Balances (Deta

Revenue Contract Balances (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Contract with Customer, Asset, before Allowance for Credit Loss		$ 16	$ 20	$ 25	$ 40
Contract assets, additions/(deletions)		(9)	(21)
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)		(1)	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		4	6	5	6
Affiliated Entity
Deferred Revenue, Current		56	73	60	91
Deferred revenue, additions/(deletions)		79	59
Deferred revenue, revenue recognized	[1]	(83)	(77)
Long-term deferred revenue, additions/(deletions)		(5)	(12)
Long-term deferred revenue, revenue recognized	[1]	0	0
Affiliated Entity | Due to related parties, noncurrent
Contract with Customer, Liability, Noncurrent		26	36	31	48
Third Party [Member]
Deferred Revenue, Current		63	50	56	37
Deferred revenue, additions/(deletions)		40	40
Deferred revenue, revenue recognized	[1]	(33)	(27)
Long-term deferred revenue, additions/(deletions)		27	11
Long-term deferred revenue, revenue recognized	[1]	0	0
Third Party [Member] | Deferred revenue, noncurrent
Contract with Customer, Liability, Noncurrent		$ 162	$ 130	$ 135	$ 119
[1]No significant revenue was recognized related to past performance obligations in the current periods.

Revenue Remaining Performance O

Revenue Remaining Performance Obligations (Details) $ in Millions	Sep. 30, 2022 USD ($)
Revenue from Contract with Customer [Abstract]
Contract with customer, liability	$ 306
Revenue, Remaining Performance Obligation, Amount	8,910	[1],[2],[3]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 497
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	3 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	$ 1,787
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	$ 1,665
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	$ 1,596
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	$ 1,427
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	$ 1,938
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	21 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]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.[3]Revenues classified as Rental income and Sales-type lease revenue are excluded from this table.

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities	$ 642	$ 627
Income Taxes Paid, Net	2	2
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	$ 0	$ 1

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information - Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Increase/ (decrease) in capital accruals	$ 39	$ (19)
Payments to Acquire Property, Plant, and Equipment	535	374
Capital Expenditure	$ 574	$ 355

Leases, Codification Topic 84_2

Leases, Codification Topic 842 (Details) - USD ($) $ in Millions		3 Months Ended							9 Months Ended
		Sep. 30, 2022		Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022		Sep. 30, 2021	Aug. 01, 2022	Jul. 31, 2022	Dec. 31, 2021	Apr. 30, 2021
Lessor, Lease, Description [Line Items]
Operating Lease, Lease Income		$ 75				$ 88			$ 268		$ 286
Operating Lease, Lease Income, Related Party		201				164			564		574
Sales-type Lease, Revenue		28				0			28		0
Sales-type Lease, Selling Profit (Loss)		509				0			509		0
Sales-type lease revenue, related parties		118				132			343		305
Sales-type Lease, Lease Receivable	[1]	1,935							1,935
Sales-type Lease, Unguaranteed Residual Asset	[2]	140							140
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		172							172
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years		644							644
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		635							635
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		625							625
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		585							585
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		1,666							1,666
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		4,327							4,327
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		2,392							2,392
Sales-type Lease, Interest Income	[3]	208							208
Net Investment in Lease, Noncurrent	[2]	1,727							1,727
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		2,075							2,075
Partners' Capital Account, Contributions		55		$ 2	$ 10	16	$ 122	$ 7
Reclassification, Other
Lessor, Lease, Description [Line Items]
Property, Plant and Equipment, Transfers and Changes									20
Third Party [Member]
Lessor, Lease, Description [Line Items]
Sales-type Lease, Selling Profit (Loss)		509	[4]			0			509	[4]	0
Sales-type Lease, Interest Income		19				0			19		0
Sales-type Lease, Variable Lease Income		9				0			9		0
Sales-type Lease, Lease Receivable		944	[1]			0			944	[1]	0		$ 914
Sales-type Lease, Unguaranteed Residual Asset		63	[2]			0			63	[2]	0		$ 63
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		53							53
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years		166							166
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		156							156
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		146							146
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		136							136
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		1,096							1,096
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		1,753							1,753
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		809							809
Sales-type Lease, Interest Income	[3]	106							106
Net Investment in Lease, Noncurrent	[2]	838							838
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		1,007							1,007
Affiliated Entity
Lessor, Lease, Description [Line Items]
Sales-type Lease, Interest Income		114				132			336		305
Sales-type Lease, Variable Lease Income		4				0			7		0
Sales-type Lease, Lease Receivable						0					0	$ 79			$ 519
Sales-type Lease, Unguaranteed Residual Asset		77				0			77		0	$ 6		$ 47	$ 14
Sales-type Lease, Interest Income		102							102					82
Net Investment in Lease, Noncurrent		889							889					$ 854
Marathon Petroleum Corporation [Member]
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable	[1]	991							991
Sales-type Lease, Unguaranteed Residual Asset	[2]	77							77
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		119							119
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years		478							478
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		479							479
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		479							479
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		449							449
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		570							570
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		2,574							2,574
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		1,583							1,583
Sales-type Lease, Interest Income	[3]	102							102
Net Investment in Lease, Noncurrent	[2]	889							889
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		1,068							1,068
Marathon Petroleum Corporation [Member] | Limited Partners Common Units [Member]
Lessor, Lease, Description [Line Items]
Partners' Capital Account, Contributions		55		$ 2	$ 10	16	$ 122	$ 7
Marathon Petroleum Corporation [Member] | Limited Partners Common Units [Member] | Gain (loss) on sales-type lease
Lessor, Lease, Description [Line Items]
Partners' Capital Account, Contributions	[5]	$ 43				$ 0			$ 43		$ 112
[1]This amount does not include the unguaranteed residual assets.[2]The related-party balance is presented in Noncurrent assets - related parties and the third-party balance is presented in Other noncurrent assets in the Consolidated Balance Sheets.[3]The related-party balance is presented in Current assets - related parties and the third-party balance is presented in Receivables, net in the Consolidated Balance Sheets.[4]The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income.[5]The amount recognized on commencement date was recorded as a Contribution from MPC in the Consolidated Statements of Equity given the underlying agreements are between entities under common control

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	9 Months Ended
	Dec. 15, 2020	Jul. 31, 2020	Sep. 30, 2022	Dec. 31, 2021
Commitments And Contingencies [Line Items]
Accrued liabilities for environmental remediation			$ 22	$ 23
Loss Contingency, Damages Sought, Value		$ 187
Loss Contingency, Damages Paid, Value	$ 4
Guarantor Obligations, Origin and Purpose			Guarantees related to indebtedness of equity method investeesWe 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 pending completion of the EIS. The EIS has been delayed and the Army Corps currently expects to release a draft EIS in the first half of 2023.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 September 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