MPLX (MPLX) 10-K 23 Feb 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2022	Feb. 16, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-35714
Entity Registrant Name	MPLX LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-0005456
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	45840-3229
City Area Code	419
Local Phone Number	421-2414
Title of 12(b) Security	Common Units Representing Limited Partnership Interests
Trading Symbol	MPLX
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 10.6
Entity Common Stock, Shares Outstanding		1,001,043,931
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Central Index Key	0001552000
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2022
Document Information [Line Items]
Document Transition Report	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2022
Auditor Information [Abstract]
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Toledo, Ohio

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Revenues and other income:
Operating Lease, Lease Income	$ 327		$ 376		$ 398
Operating Lease, Lease Income, Related Party	763		743		952
Sales-type Lease, Revenue	62		0		0
Sales-type lease revenue, related parties	465		435		152
Income (Loss) from Equity Method Investments	476		321	[1]	(936)	[1]
Other Income	485	[2]	21		5
Related Party Transaction, Other Revenues from Transactions with Related Party	111		110		102
Revenues, Total	11,613		10,027		7,569
Costs and expenses:
Costs and Expenses, Related Party	1,413		1,219		1,116
Cost, Depreciation and Amortization	1,230		1,287		1,377
Goodwill and Intangible Asset Impairment	0		42		2,165
General and Administrative Expense	335		353		378
Restructuring Charges	0		0		37
Taxes, Miscellaneous	115		120		125
Costs and Expenses, Total	6,702		6,035		7,358
Operating Income (Loss), Total	4,911		3,992		211
Interest Expense, Related Party	5		8		5
Interest expense	843		785		829
Interest Expense, Other	77		86		62
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	3,986		3,113		(685)
Income Tax Expense (Benefit)	8		1		2
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total	3,978		3,112		(687)
Net Income (Loss) Attributable to Noncontrolling Interest	34		35		33
Net Income (Loss) Attributable to Parent, Total	3,944	[3]	3,077		(720)
Net Income (Loss) Allocated to Limited Partners	$ 3,815		$ 2,936		$ (842)
Net Income Attributable To Parent Company Per Limited Partner Unit Basic And Diluted [Abstract]
Common - basic (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Common - diluted (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Limited Partners' Capital Account [Abstract]
Common - basic (in units)	1,010		1,027		1,051
Common - diluted (in units)	1,010		1,027		1,051
Other VIEs and Non-VIEs [Member]
Revenues and other income:
Revenues, Total	$ 2,653		$ 2,056		$ 1,506
Costs and expenses:
Costs and Expenses, Total	1,251		1,058		945
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total	$ 1,246		$ 860		$ 440
Limited Partners Common Units
Net Income Attributable To Parent Company Per Limited Partner Unit Basic And Diluted [Abstract]
Common - basic (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Common - diluted (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Limited Partners' Capital Account [Abstract]
Common - basic (in units)	1,010		1,027		1,051
Common - diluted (in units)	1,010		1,027		1,051
Third Party
Revenues and other income:
Sales-type Lease, Revenue	$ 62		$ 0		$ 0
Costs and expenses:
Direct Costs of Leased and Rented Property or Equipment	123		136		135
Affiliated Entity
Costs and expenses:
Direct costs of leased and rented property or equipment, related parties	54		109		160
Service [Member]
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax	2,359		2,313		2,397
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	3,754		3,628		3,580
Product [Member]
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax	2,219		1,590		636
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	198		145		128
Product [Member] | Third Party
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax	2,219		1,590		636
Oil and Gas, Refining and Marketing [Member]
Costs and expenses:
Cost of Goods and Services Sold	1,369		1,184		1,326
Natural Gas, Midstream [Member]
Costs and expenses:
Cost of Goods and Services Sold	2,063		1,585		539
Service, Other [Member]
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax	394		345		155
Series A Preferred Stock [Member]
Costs and expenses:
Preferred Stock Dividends, Income Statement Impact	88		100		81
Series B Preferred Stock [Member]
Costs and expenses:
Preferred Stock Dividends, Income Statement Impact	$ 41		$ 41		$ 41
[1]The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively.[2]2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information.[3]The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information.

Consolidated Statements of In_2

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Income [Member]
Sales-type Lease, Selling Profit (Loss)	$ 509	$ 0	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income Statement - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 3,978	$ 3,112	$ (687)
Other comprehensive income/(loss), net of tax:
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Adjustment, Net of Tax	9	(2)	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total	3,987	3,110	(687)
Less comprehensive income attributable to:
Net Income (Loss) Attributable to Noncontrolling Interest	34	35	33
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	$ 3,953	$ 3,075	$ (720)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Assets, Current [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 238	$ 13
Accounts Receivable, after Allowance for Credit Loss, Current	737	654
Due from Related Parties, Current	729	644
Inventory, Gross	148	142
Assets, Current, Total	1,905	1,507
Equity Method Investments	4,095	3,981
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	18,848	20,042
Intangible Assets, Net (Excluding Goodwill)	705	831
Goodwill	7,645	7,657
Due from Related Parties, Noncurrent	1,225	1,161
Other Assets, Noncurrent	959	60
Assets, Total	35,665	35,507
Liabilities, Current [Abstract]
Accounts Payable, Current	224	172
Accrued Liabilities, Current	269	363
Due to Related Parties, Current	343	1,780
Accrued Property Plant and Equipment Current	128	97
Debt, Current	988	499
Interest Payable	237	202
Other Liabilities, Current	166	176
Total current liabilities	2,401	3,348
Deferred Revenue, Noncurrent	219	383
Due to Related Parties, Noncurrent	338	302
Long-term Debt and Lease Obligation	18,808	18,072
Deferred Income Tax Liabilities, Net	13	10
Deferred Credits and Other Liabilities, Noncurrent	142	170
Total liabilities	22,151	22,490
Commitments and contingencies (see Note 21)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Accumulated other comprehensive loss	(8)	(17)
Total MPLX LP partners’ capital	12,309	11,811
Noncontrolling interests	237	241
Total equity	12,546	12,052
Total liabilities, preferred units and equity	35,665	35,507
Public
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited Partners' Capital Account	8,413	8,579
Third Party
Assets, Current [Abstract]
Other Assets, Current	53	54
Operating Lease, Right-of-Use Asset	283	268
Liabilities, Current [Abstract]
Operating Lease, Liability, Current	46	59
Deferred Revenue, Noncurrent		0
Operating Lease, Liability, Noncurrent	230	205
Marathon Petroleum Corporation [Member]
Assets, Current [Abstract]
Operating Lease, Right-of-Use Asset	228	229
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited Partners' Capital Account, Related Party	3,293	2,638
Affiliated Entity
Liabilities, Current [Abstract]
Due to Related Parties, Current	343	1,780
Due to Related Parties, Noncurrent	338	302
Limited Partners Common Units | Public
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited Partners' Capital Account	8,413	8,579
Limited Partners Common Units | Marathon Petroleum Corporation [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited Partners' Capital Account	3,293	2,638
Series B Preferred Stock [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred Units, Preferred Partners' Capital Accounts	611	611
Series A Preferred Stock [Member]
Liabilities, Current [Abstract]
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests	$ 968	$ 965

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - shares	Dec. 31, 2022	Dec. 31, 2021
Units outstanding	1,001,020,616	1,016,178,378
Limited Partners Common Units | Public
Units issued	354,000,000	369,000,000
Units outstanding	354,000,000	369,000,000
Limited Partners Common Units | Marathon Petroleum Corporation [Member]
Units issued	647,000,000	647,000,000
Units outstanding	647,415,452	647,000,000
Series B Preferred Stock [Member]
Preferred Units, Issued	600,000	600,000
Preferred Units, Outstanding	600,000	600,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2020
Operating activities:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 3,978	$ 3,112		$ (687)
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs	73	70		61
Cost, Depreciation and Amortization	1,230	1,287		1,377
Goodwill and Intangible Asset Impairment	0	42		2,165
Deferred income taxes	3	(2)		(1)
Loss/(gain) on disposal of assets	34	(13)		4
Income (Loss) from Equity Method Investments	(476)	(321)	[1]	936	[1]
Distributions from unconsolidated affiliates	578	508		459
Increase (Decrease) in Derivative Assets and Liabilities	(47)	45		3
Changes in:
Receivables	14	(199)		62
Inventories	(5)	(24)		(12)
Accounts payable and accrued liabilities	(33)	193		36
Assets/liabilities - related parties	40	101		8
Increase (Decrease) in Other Operating Assets and Liabilities, Net	(3)	(2)		(5)
Deferred revenue	108	88		112
All other, net	34	26		3
Net cash provided by operating activities	5,019	4,911		4,521
Investing activities:
Additions to property, plant and equipment	(806)	(529)		(1,183)
Acquisitions, net of cash acquired	(28)	0		0
Disposal of assets	84	126		56
Investments in unconsolidated affiliates	(217)	(151)		(266)
Distributions from unconsolidated affiliates - return of capital	11	36		123
All other, net	0	0		8
Net cash used in investing activities	(956)	(518)		(1,262)
Financing activities:
Proceeds from long-term lines of credit	3,379	4,175		6,810
Repayments of Debt	2,202	5,821		6,414
Debt issuance costs	(29)	0		(25)
Payments for Repurchase of Common Stock	(491)	(630)		(33)
Distributions to noncontrolling interests	(38)	(39)		(37)
Distributions to unitholders and general partner	(2,921)	(3,432)		(2,884)
Contributions from MPC	44	45		50
All other, net	(4)	(2)		(10)
Net Cash Provided by (Used in) Financing Activities	(3,838)	(4,395)		(3,259)
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect, Total	225	(2)		0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning Balance	13	15		15
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	238	13		15
Other Income [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Sales-type Lease, Selling Profit (Loss)	(509)	0		0
Related Party Revolving Credit Agreement
Financing activities:
Related party debt - borrowings	2,989	8,493		6,264
Related party debt - repayments	(4,439)	(7,043)		(6,858)
Series A Preferred Stock [Member]
Financing activities:
Distributions to Series A preferred unitholders	(85)	(100)		(81)
Series B Preferred Stock [Member]
Financing activities:
Distributions to Series A preferred unitholders	$ (41)	$ (41)		$ (41)
[1]The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively.

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Series B Preferred Stock [Member]	Series A Preferred Stock [Member]	Public	Public Limited Partners Common Units	Marathon Petroleum Corporation [Member] Limited Partners Common Units	AOCI Attributable to Parent	Noncontrolling Interest
Limited Partners' Capital Account					$ 10,800	$ 4,968
Preferred Units, Preferred Partners' Capital Accounts		$ 611
Accumulated other comprehensive loss	$ (15)
Noncontrolling interests	249
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests			$ 968
Partners' Capital, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2019	16,613
Stockholders' Equity, Other	5	0			6	(1)	$ 0	$ 0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity	768	(41)			307	535	0	(33)
Stock Repurchased and Retired During Period, Value	(33)	0	0		(33)	0	0	0
Partners' Capital Account, Distributions	(2,959)	(41)	(81)		(1,082)	(1,799)	0	(37)
Partners' Capital Account, Contributions	261	0	0		0	261	0	0
Partners' Capital, Business Unit Exchanged for Common Units	(102)	0	0		0	(102)	0	0
Partners' Capital, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2020	13,017
Net income allocated			81
Temporary Equity, Other Changes			0
Limited Partners' Capital Account					9,384	2,792
Preferred Units, Preferred Partners' Capital Accounts		611
Accumulated other comprehensive loss	(15)
Noncontrolling interests	245
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests			968
Stockholders' Equity, Other	2	0			4	0	(2)	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity	(3,012)	(41)			(1,087)	(1,849)	0	(35)
Stock Repurchased and Retired During Period, Value	(630)	0	0		(630)	0	0	0
Partners' Capital Account, Distributions	(3,512)	(41)	(100)		(1,269)	(2,163)	0	(39)
Partners' Capital Account, Contributions	160	0	0		0	160	0	0
Unit conversion	(3)	0	3		(3)	0	0	0
Partners' Capital, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2021	12,052
Net income allocated			100
Temporary Equity, Other Changes			0
Limited Partners' Capital Account				$ 8,579	8,579	2,638
Preferred Units, Preferred Partners' Capital Accounts		611
Accumulated other comprehensive loss	(17)
Noncontrolling interests	241
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests			965
Stockholders' Equity, Other	13	0			4	0	9	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Excluding Portion Attributable to Temporary Equity	(3,890)	(41)			(1,371)	(2,444)	0	(34)
Stock Repurchased and Retired During Period, Value	(491)	0	0		(491)	0	0	0
Partners' Capital Account, Distributions	(3,000)	(41)	(85)		(1,050)	(1,871)	0	(38)
Partners' Capital Account, Contributions	82	0	0		0	82	$ 0	$ 0
Partners' Capital, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2022	12,546
Net income allocated			88
Temporary Equity, Other Changes			0
Limited Partners' Capital Account				$ 8,413	$ 8,413	$ 3,293
Preferred Units, Preferred Partners' Capital Accounts		$ 611
Accumulated other comprehensive loss	(8)
Noncontrolling interests	$ 237
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests			$ 968

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2022
Limited Liability Company or Limited Partnership, Business Organization and Operations [Abstract]
Business Description and Basis of Presentation	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 our sponsor and customer, “MPC,” refer collectively to Marathon Petroleum Corporation and its subsidiaries, other than the Partnership. We are engaged in the gathering, transportation, storage and distribution of crude oil, refined products, other hydrocarbon-based products and renewables; 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 was formed on March 27, 2012 as a Delaware limited partnership and completed its initial public offering on October 31, 2012. 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, other hydrocarbon-based products and renewables; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 10 for additional information regarding the operations and results of these segments. On July 31, 2020, MPLX completed the exchange of Western Refining Wholesale, LLC (WRW”) to Western Refining Southwest, Inc. (now known as Western Refining Southwest LLC) (“WRSW”), a wholly owned subsidiary of MPC, in exchange for the redemption of 18,582,088 MPLX common units held by WRSW (the “Wholesale Exchange”). See Note 4 for additional information regarding the Wholesale Exchange. These financial statements include the results of WRSW through July 31, 2020. Basis of Presentation The accompanying consolidated financial statements of MPLX have been prepared in accordance with GAAP. The 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.

Summary of Principal Accounting

Summary of Principal Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Summary of Principal Accounting Policies Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the respective reporting periods. Actual results could differ materially from those estimates. Estimates are subject to uncertainties due to the levels of subjectivity and judgment necessary to account for highly uncertain matters or the susceptibility of such matters to change and affect items such as valuing identified intangible assets; determining the fair value of derivative instruments; evaluating impairments of long-lived assets, goodwill and equity investments; establishing estimated useful lives for long-lived assets; acquisition accounting; estimating revenues, expense accruals and capital expenditures; valuing AROs; recognizing share-based compensation expense; and determining liabilities, if any, for environmental and legal contingencies. Revenue Recognition Revenue is measured based on consideration specified in a contract with a customer. MPLX recognizes revenue when it satisfies a performance obligation by transferring control over a product or providing services to a customer. MPLX enters into a variety of contract types in order to generate Product sales and Service revenue. MPLX provides services under the following types of arrangements: • Fee-based arrangements – Under fee-based arrangements, MPLX receives fees for the following services: gathering, processing and transportation of natural gas; transportation, fractionation, exchange and storage of NGLs; and transportation, terminalling, storage and distribution of crude oil, refined products, other hydrocarbon-based products, and renewables. The revenue MPLX earns from these arrangements is generally directly related to the volume of natural gas, NGLs, refined products or crude oil that is handled by or flows through MPLX’s systems and facilities and is not normally directly dependent on commodity prices. In certain cases, MPLX’s arrangements provide for minimum volume commitments. Fee-based arrangements are reported as Service revenue on the Consolidated Statements of Income. Revenue is recognized over time as services are performed. In certain instances when specifically stated in the contract terms, MPLX purchases product after fee-based services have been provided. Revenue from the sale of products purchased after services are provided is reported as Product sales on the Consolidated Statements of Income and recognized on a gross basis, as MPLX takes control of the product and is the principal in the transaction. • Percent-of-proceeds arrangements – Under percent-of-proceeds arrangements, MPLX gathers and processes natural gas on behalf of producers; sells the resulting residue gas, condensate and NGLs at market prices; and remits to producers an agreed-upon percentage of the proceeds. In other cases, instead of remitting cash payments to the producer, MPLX delivers an agreed-upon percentage of the residue gas and NGLs to the producer (take-in-kind arrangements) and sells the volumes MPLX retains to third parties or related parties. Revenue is recognized on a net basis when MPLX acts as an agent and does not have control of the gross amount of gas and/or NGLs prior to it being sold. Percent-of-proceeds revenue is reported as Service revenue - product related on the Consolidated Statements of Income. • Keep-whole arrangements – Under keep-whole arrangements, MPLX gathers natural gas from the producer, processes the natural gas and sells the resulting condensate and NGLs to third parties at market prices. Because the extraction of the condensate and NGLs from the natural gas during processing reduces the Btu content of the natural gas, MPLX must either purchase natural gas at market prices for return to producers or make cash payment to the producers equal to the value of the energy content of this natural gas. Certain keep-whole arrangements also have provisions that require MPLX to share a percentage of the keep-whole profits with the producers based on the oil to gas ratio or the NGL to gas ratio. Service revenue - product related is recorded based on the value of the NGLs received on the date the services are performed. Natural gas purchased to return to the producer and shared NGL profits are recorded as a reduction of Service revenue - product related on the Consolidated Statements of Income on the date the services are performed. Sales of NGLs under these arrangements are reported as Product sales on the Consolidated Statements of Income and are reported on a gross basis as MPLX is the principal in the arrangement and controls the product prior to sale. The sale of the NGLs may occur shortly after services are performed at the tailgate of the plant, or after a period of time as determined by MPLX. • Purchase arrangements – Under purchase arrangements, MPLX purchases natural gas at either the wellhead or the tailgate of a plant. MPLX then gathers and delivers the natural gas to pipelines where MPLX may resell the natural gas. Wellhead purchase arrangements represent an arrangement with a supplier and are recorded in Purchased product costs. Often, MPLX earns fees for services performed prior to taking control of the product in these arrangements and Service revenue is recorded for these fees. Revenue generated from the sale of product obtained in tailgate purchase arrangements is reported as Product sales on the Consolidated Statements of Income and is recognized on a gross basis as MPLX purchases and takes control of the product prior to sale and is the principal in the transaction. In many cases, MPLX provides services under contracts that contain a combination of more than one of the arrangements described above. When fees are charged (in addition to product received) under percent-of-proceeds arrangements, keep-whole arrangements or purchase arrangements, MPLX records such fees as Service revenue on the Consolidated Statements of Income. The terms of MPLX’s contracts vary based on gas quality conditions, the competitive environment when the contracts are signed, and customer requirements. Performance obligations are determined based on the specific terms of the arrangements, economics of the geographical regions, and the services offered and whether they are deemed distinct. MPLX allocates the consideration earned between the performance obligations based on the stand-alone selling price when multiple performance obligations are identified. Revenue from MPLX’s service arrangements will generally be recognized over time as the performance obligation is satisfied as services are provided. MPLX has elected to use the output measure of progress to recognize revenue based on the units delivered, processed or transported. The transaction price may have fixed components related to minimum volume commitments and variable components, which are primarily dependent on volumes. Variable consideration will generally not be estimated at contract inception as the transaction price is specifically allocable to the services provided each period. In instances in which tiered pricing structures do not reflect our efforts to perform, MPLX will estimate variable consideration at contract inception. Product sales will be recognized at a point in time when control of the product transfers to the customer. Minimum volume commitments may create contract liabilities if current period payments can be used for future services. Breakage is estimated and recognized into service revenue in instances where it is probable the customer will not use the credit in future periods. Amounts billed to customers for shipping and handling, electricity, and other costs to perform services are included in the transaction price as a component of Revenues and other income on the Consolidated Statements of Income. Shipping and handling costs associated with product sales are included in Purchased product costs on the Consolidated Statements of Income. Customers usually pay monthly based on the products purchased or services performed that month. Taxes collected from customers and remitted to the appropriate taxing authority are excluded from revenue. Based on the terms of certain contracts, MPLX is considered to be the lessor under several implicit operating and sales-type lease arrangements in accordance with GAAP. Revenue and costs related to the portion of the revenue earned under these contracts considered to be implicit operating leases are recorded as Rental income and Rental cost of sales, respectively, on the Consolidated Statements of Income. Revenue related to the portion of the revenue earned under these contracts considered to be implicit sales-type lease arrangements is recorded as Sales-type lease revenue on the Consolidated Statements of Income, while related costs are recorded to Cost of revenues or Purchases - related parties. Revenue and Expense Accruals MPLX routinely makes accruals based on estimates for both revenues and expenses due to the timing of compiling billing information, receiving certain third-party information and reconciling MPLX’s records with those of third parties. The delayed information from third parties includes, among other things, actual volumes purchased, transported or sold, adjustments to inventory and invoices for purchases, actual natural gas and NGL deliveries, and other operating expenses. MPLX makes accruals to reflect estimates for these items based on its internal records and information from third parties. Estimated accruals are adjusted when actual information is received from third parties and MPLX’s internal records have been reconciled. Other Taxes Other taxes primarily include real estate taxes. Cash and Cash Equivalents Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid debt instruments with maturities of three months or less. Receivables Receivables primarily consist of customer accounts receivable, which are recorded at the invoiced amount and generally do not bear interest. Allowances for doubtful accounts are generally recorded when it becomes probable that the receivable will not be collected and are recorded to bad debt expense. We review the allowance quarterly with past-due balances over 150 days and other higher-risk amounts being reviewed individually for collectability. Balances that remain outstanding after reasonable collection efforts have been unsuccessful are written off through a charge to the valuation allowance and a credit to accounts receivable. Leases Contracts with a term greater than one year that convey the right to direct the use of and obtain substantially all of the economic benefit of an asset are accounted for as right of use (“ROU”) assets and lease liabilities. Right of use asset and lease liability balances are recorded at the commencement date at present value of the fixed lease payments using a secured incremental borrowing rate with a maturity similar to the lease term because our leases do not provide implicit rates. We have elected to include both lease and non-lease components in the present value of the lease payments for all lessee asset classes with the exception of our marine and third-party contractor service and equipment leases. The lease component of the payment for the marine and equipment asset classes is determined using a relative standalone selling price. Operating lease expense is recognized on a straight-line basis over the lease term. See Note 20 for additional disclosures about our lease contracts. As a lessor under ASC 842, MPLX may be required to re-classify existing operating leases to sales-type leases upon modification and related reassessment of the leases. See Note 20 for further information regarding our ongoing evaluation of the impacts of lease reassessments as modifications occur. The net investment in sales-type leases with third parties is recorded within Receivables, net and Other noncurrent assets on the Consolidated Balance Sheets. The net investment in sales-type leases with related parties is recorded within Current assets - related parties and Noncurrent assets - related parties on the Consolidated Balance Sheets. These amounts are comprised of the present value of the sum of the future minimum lease payments representing the value of the lease receivable and the unguaranteed residual value of the leased assets. Management assesses the net investment in sales-type leases for recoverability quarterly. Inventories Inventories consist of materials and supplies to be used in operations, line fill and other NGLs. Cost for materials and supplies are determined primarily using the weighted-average cost method. Inventories are valued at the lower of cost or net realizable value. Imbalances Within our pipelines and storage assets, we experience volume gains and losses due to pressure and temperature changes, evaporation and variances in meter readings and other measurement methods. Until settled, positive imbalances are recorded as other current assets and negative imbalances are recorded as accounts payable. Positive and negative imbalances are settled in cash, settled by physical delivery of volumes from a different source, or tracked and settled in the future. Investment in Unconsolidated Affiliates Equity investments in which MPLX exercises significant influence but does not control and is not the primary beneficiary, are accounted for using the equity method and are reported in Equity method investments on the accompanying Consolidated Balance Sheets. This includes entities in which we hold majority ownership, but the minority shareholders have substantive participating rights. Differences in the basis of the investments and the separate net asset values of the investees, if any, are amortized into net income over the remaining useful lives of the underlying assets and liabilities, except for the excess related to goodwill. Regular evaluation of these investments is appropriate to evaluate any potential need for impairment. MPLX uses evidence of a loss in value to identify if an investment has an other than a temporary decline. Impairments are recorded through Income from equity method investments. Property, Plant and Equipment Property, plant and equipment are recorded at cost and depreciated on a straight-line basis over the estimated useful lives of the assets. Expenditures that extend the useful lives of assets are capitalized. 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 flows 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 future cash flows from the use of the asset group and its eventual disposition is less than the carrying value of an asset group, an impairment assessment is performed and the excess of the book value over the fair value is recorded as an impairment loss. When items of property, plant and equipment are sold or otherwise disposed of, any gains or losses are reported on the Consolidated Statements of Income. Gains on the disposal of property, plant and equipment are recognized when they occur, which is generally at the time of closing. If a loss on disposal is expected, such losses are recognized when the assets are classified as held for sale. Interest costs for the construction or development of long-lived assets are capitalized and amortized over the related asset’s estimated useful life. Goodwill and Intangibles Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in the acquisition of a business. Goodwill is not amortized, but rather is tested for impairment at the reporting unit level annually and when events or changes in circumstances indicate that the fair value of a reporting unit with goodwill has been reduced below carrying value. If we determine, based on a qualitative assessment, that it is not more likely than not that a reporting unit’s fair value is less than its carrying amount, no further impairment testing is required. If we do not perform a qualitative assessment or if that assessment indicates that further impairment testing is required, the fair value of each reporting unit is determined using an income and market approach which is compared to the carrying value of the reporting unit. If the carrying amount of the reporting unit exceeds its fair value, an impairment loss would be recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to that reporting unit. The fair value under the income approach is calculated using the expected present value of future cash flows method. Significant assumptions used in the cash flow forecasts include future net operating margins, future volumes, discount rates, and future capital requirements. See Note 14 for further details. Amortization of intangibles with definite lives is calculated using the straight-line method, which is reflective of the benefit pattern in which the estimated economic benefit is expected to be received over the estimated useful life of the intangible asset. Intangibles subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the intangible may not be recoverable. If the sum of the expected undiscounted future cash flows related to the asset is less than the carrying amount of the asset, an impairment loss is recognized based on the fair value of the asset. Environmental Costs Environmental expenditures for additional equipment that mitigates or prevents future contamination or improves environmental safety or efficiency of the existing assets are capitalized. We recognize remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs can be reasonably estimated. The timing of remediation accruals coincides with completion of a feasibility study or the commitment to a formal plan of action. Remediation liabilities are accrued based on estimates of known environmental exposure and are discounted when the estimated amounts are reasonably fixed and determinable. If recoveries of remediation costs from third parties are probable, a receivable is recorded and is discounted when the estimated amount is reasonably fixed and determinable. Asset Retirement Obligations An ARO is a legal obligation associated with the retirement of tangible long-lived assets that generally result from the acquisition, construction, development or normal operation of the asset. The fair value of AROs is recognized in the period in which the obligations are incurred, if a reasonable estimate of fair value can be made, and added to the carrying amount of the associated asset. This additional carrying amount is then depreciated over the life of the asset. The liability is determined using a credit adjusted risk free interest rate and increases due to the passage of time based on the time value of money until the obligation is settled. AROs have not been recognized for certain assets because the fair value cannot be reasonably estimated since the settlement dates of the obligations are indeterminate. Such obligations will be recognized in the period when sufficient information becomes available to estimate a range of potential settlement dates. As of December 31, 2022 and 2021, MPLX’s asset retirement obligation was $34 million and $31 million, respectively, and is included on the balance sheet within Other long-term liabilities. Derivative Instruments MPLX may use commodity derivatives to economically hedge a portion of its exposure to commodity price risk. All derivative instruments (including derivatives embedded in other contracts) are recorded at fair value. MPLX discloses the fair value of all derivative instruments under the captions Other current assets, Other noncurrent assets, Other current liabilities and Other long-term liabilities on the Consolidated Balance Sheets. 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. Changes in the fair value of derivative instruments are reported on the Consolidated Statements of Income in accounts related to the item whose value or cash flows are being managed. Derivative instruments are marked to market through Purchased product costs on the Consolidated Statements of Income. Certain commodity derivative positions are governed by master netting arrangements and are reflected on the consolidated balance sheets on a net basis by counterparty. MPLX did not utilize any commodity derivatives during the years ended December 31, 2022, 2021 and 2020, and therefore did not elect hedge accounting. MPLX has historically elected the normal purchases and normal sales designation for certain contracts related to the physical purchase of electric power and the sale of some commodities. Fair Value Measurement Financial assets and liabilities recorded at fair value in the Consolidated Balance Sheets are categorized based upon the fair value hierarchy established by GAAP, which classifies the inputs used to measure fair value into Level 1, Level 2 or Level 3. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The methods and assumptions utilized may produce a fair value that may not be realized in future periods upon settlement. Furthermore, while MPLX believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. For further discussion, see Note 15. Equity-Based Compensation Arrangements MPLX issues phantom units under the MPLX LP 2018 Incentive Compensation Plan. A phantom unit entitles the grantee a right to receive a common unit upon the issuance of the phantom unit. The fair value of phantom unit awards granted to employees and non-employee directors is based on the fair market value of MPLX LP common units on the date of grant. The fair value of the units awarded is amortized into earnings using a straight-line amortization schedule over the period of service corresponding with the vesting period. For phantom units that vest immediately and are not forfeitable, equity-based compensation expense is recognized at the time of grant. MPLX previously issued performance units under the MPLX LP 2018 Incentive Compensation Plan. Performance units paying out in cash are accounted for as liability awards and recorded at fair value with a mark-to-market adjustment made each quarter. The performance units paying out in units are accounted for as equity awards. Equity-classified performance units with a market condition use a Monte Carlo valuation model to calculate a grant date fair value of market conditions. Equity-classified performance units with a performance condition are valued based on the grant date fair value of the payout deemed most probable to occur and is adjusted as the expectation for payout changes. All the outstanding performance unit awards have been settled as of February 1, 2023. To satisfy common unit awards, MPLX may issue new common units, acquire common units in the open market or use common units already owned by the general partner. Income Taxes MPLX is not a taxable entity for United States federal income tax purposes or for the majority of the states that impose an income tax. Taxes on MPLX’s net income generally are borne by its partners through the allocation of taxable income. MPLX’s taxable income or loss, which may vary substantially from the net income or loss reported on the Consolidated Statements of Income, is includable in the federal income tax returns of each partner. MPLX and certain legal entities are, however, taxable entities under certain state jurisdictions. MPLX accounts for income taxes under the asset and liability method. Deferred income taxes are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, capital loss carryforwards and net operating loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of any tax rate change on deferred taxes is recognized as tax expense/(benefit) from continuing operations in the period that includes the enactment date of the tax rate change. Realizability of deferred tax assets is assessed and, if not more likely than not, a valuation allowance is recorded to reflect the deferred tax assets at net realizable value as determined by management. All deferred tax balances are classified as long-term in the accompanying Consolidated Balance Sheets. All changes in the tax bases of assets and liabilities are allocated among operations and items charged or credited directly to equity. Distributions In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule, as discussed in Notes 7 and 9, and subsequently allocated to the limited partner unitholders. Distributions, although earned, are not accrued as a liability until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described below. Net Income Per Limited Partner Unit MPLX uses the two-class method when calculating the net income per unit applicable to limited partners, because there is more than one class of participating security. The classes of participating securities include common units, Series A and Series B preferred units and certain equity-based compensation awards. Net income attributable to MPLX LP is allocated to the unitholders differently for preparation of the Consolidated Statements of Equity and the calculation of net income per limited partner unit. In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule and subsequently allocated to remaining unitholders in accordance with their respective ownership percentages. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 8. In preparing net income per limited partner units, during periods in which a net loss attributable to MPLX is reported or periods in which the total distributions exceed the reported net income attributable to MPLX’s unitholders, the amount allocable to certain equity-based compensation awards is based on actual distributions to the equity-based compensation awards. Diluted earnings per unit is calculated by dividing net income attributable to MPLX’s common unitholders, after deducting amounts allocable to other participating securities, by the weighted average number of common units and potential common units outstanding during the period. Potential common units are excluded from the calculation of diluted earnings per unit during periods in which net income attributable to MPLX’s unitholders, after deducting amounts that are allocable to the outstanding equity-based compensation awards and preferred units, is a loss, as the impact would be anti-dilutive. Business Combinations We recognize and measure the assets acquired and liabilities assumed in a business combination based on their estimated fair values at the acquisition date. Any excess or deficit of the purchase consideration when compared to the fair value of the net tangible assets acquired, if any, is recorded as goodwill or gain from a bargain purchase. Depending on the nature of the transaction, management may engage an independent valuation specialist to assist with the determination of fair value of the assets acquired, liabilities assumed, noncontrolling interests, if any, and goodwill, based on recognized business valuation methodologies. An income, market or cost valuation method may be utilized to estimate the fair value of the assets acquired, liabilities assumed, and noncontrolling interests, if any, in a business combination. The income valuation method represents the present value of future cash flows over the life of the asset using: (i) discrete financial forecasts, which rely on management’s estimates of volumes, certain commodity prices, revenue and operating expenses; (ii) long-term growth rates; and (iii) appropriate discount rates. The market valuation method uses prices paid for a reasonably similar asset by other purchasers in the market, with adjustments relating to any differences between the assets. The cost valuation method is based on the replacement cost of a comparable asset at prices at the time of the acquisition reduced for depreciation of the asset. If the initial accounting for the business combination is incomplete by the end of the reporting period in which the acquisition occurs, an estimate will be recorded. Subsequent to the acquisition, and not later than one year from the acquisition date, MPLX will record any material adjustments to the initial estimate based on new information obtained that would have existed as of the acquisition date. An adjustment that arises from information obtained that did not exist as of the date of the acquisition will be recorded in the period of the adjustment. Acquisition-related costs are expensed as incurred in connection with each business combination. Acquisitions in which the company or business being acquired by MPLX had an existing relationship with MPC may result in the transaction being considered a transfer between entities under common control. In these situations, MPLX records the assets acquired and liabilities assumed on its consolidated balance sheets at MPC’s historical carrying value. For the acquiring entity, transfers of businesses between entities under common control require prior periods to be retrospectively adjusted for those dates that the entity was under common control.

Accounting Standards

Accounting Standards	12 Months Ended
	Dec. 31, 2022
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Standards	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 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.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions and Dispositions Sale of Javelina On February 12, 2021, MarkWest Energy Operating Company, L.L.C., (“MarkWest Energy”) a wholly owned subsidiary of MPLX, completed the sale of all of MarkWest Energy’s equity interests in MarkWest Javelina Company L.L.C., MarkWest Javelina Pipeline Company L.L.C., and MarkWest Gas Services L.L.C. (collectively, “Javelina”) pursuant to the terms of an Equity Purchase Agreement entered into with a third party on December 23, 2020. The agreement included adjustments for working capital as well as an earnout provision based on the performance of the assets. No gain or loss was recorded on the sale. The estimated value of the earnout provision was recorded as a contingent asset shown within Other noncurrent assets on the Consolidated Balance Sheets as of December 31, 2022 and 2021. Prior to the sale, Javelina was reported within the G&P segment. Wholesale Exchange

Investments and Noncontrolling

Investments and Noncontrolling Interests	12 Months Ended
	Dec. 31, 2022
Equity Method Investments and Joint Ventures [Abstract]
Investments and Noncontrolling Interests	Investments and Noncontrolling Interests The following table presents MPLX’s equity method investments at the dates indicated: Ownership as of Carrying value at December 31, December 31, (In millions, except ownership percentages) VIE 2022 2022 2021 L&S Andeavor Logistics Rio Pipeline LLC X 67% $ 177 $ 183 Illinois Extension Pipeline Company, L.L.C. 35% 236 243 LOOP LLC 41% 287 265 MarEn Bakken Company LLC (1) 25% 475 449 Minnesota Pipe Line Company, LLC 17% 178 183 Whistler Pipeline LLC X 38% 211 155 Other (2) X 269 240 Total L&S 1,833 1,718 G&P Centrahoma Processing LLC 40% 131 133 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. X 67% 335 332 MarkWest Torñado GP, L.L.C. X 60% 306 246 MarkWest Utica EMG, L.L.C. X 57% 669 680 Rendezvous Gas Services, L.L.C. X 78% 137 147 Sherwood Midstream Holdings LLC X 51% 125 136 Sherwood Midstream LLC X 50% 512 544 Other (2) X 47 45 Total G&P 2,262 2,263 Total $ 4,095 $ 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) 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 and as such we have determined that these entities should not be consolidated and apply the equity method of accounting with respect to our investments in each entity. Sherwood Midstream 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 December 31, 2022, MPLX had 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 years ended December 31, 2022, 2021 and 2020. See Note 21 for information on our Guarantees related to indebtedness of equity method investees. During the first quarter of 2020, we recorded an other-than-temporary impairment for three joint ventures in which we have an interest. Impairment of these investments was $1,264 million, of which $1,251 million was related to MarkWest Utica EMG, L.L.C. and its investment in Ohio Gathering Company, L.L.C. The fair value of the investments was determined based upon applying the discounted cash flow method, which is an income approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future cash flows, including prices and volumes, the weighted average cost of capital and the long-term growth rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As such, the fair value of these equity method investments represents a Level 3 measurement. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment test will prove to be an accurate prediction of the future. The impairment was recorded through Income from equity method investments. The impairments were largely due to a reduction in forecasted volumes gathered and processed by the systems operated by the joint ventures. There were no additional impairments recorded during the remainder of 2020. Summarized financial information for MPLX’s equity method investments for the years ended December 31, 2022, 2021 and 2020 is as follows: December 31, 2022 (In millions) Other VIEs Non-VIEs Total Revenues and other income $ 1,197 $ 1,456 $ 2,653 Costs and expenses 603 648 1,251 Income from operations 594 808 1,402 Net income 535 711 1,246 Income from equity method investments $ 275 $ 201 $ 476 December 31, 2021 (In millions) Other VIEs Non-VIEs Total Revenues and other income $ 820 $ 1,236 $ 2,056 Costs and expenses 490 568 1,058 Income from operations 330 668 998 Net income 266 594 860 Income from equity method investments (1) $ 175 $ 146 $ 321 December 31, 2020 (In millions) Other VIEs Non-VIEs Total Revenues and other income $ 298 $ 1,208 $ 1,506 Costs and expenses 414 531 945 (Loss)/income from operations (116) 677 561 Net (loss)/income (175) 615 440 (Loss)/income from equity method investments (1) $ (1,100) $ 164 $ (936) (1) The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively. Summarized balance sheet information for MPLX’s equity method investments as of December 31, 2022 and 2021 is as follows: December 31, 2022 (In millions) Other VIEs Non-VIEs Total Current assets $ 474 $ 450 $ 924 Noncurrent assets 7,721 5,225 12,946 Current liabilities 323 181 504 Noncurrent liabilities $ 2,546 $ 876 $ 3,422 December 31, 2021 (In millions) Other VIEs Non-VIEs Total Current assets $ 335 $ 411 $ 746 Noncurrent assets 7,439 4,895 12,334 Current liabilities 217 310 527 Noncurrent liabilities $ 2,461 $ 788 $ 3,249 As of December 31, 2022 and 2021, the underlying net assets of MPLX’s investees in the G&P segment exceeded the carrying value of its equity method investments by approximately $51 million and $54 million, respectively. As of December 31, 2022 and 2021, the carrying value of MPLX’s equity method investments in the L&S segment exceeded the underlying net assets of its investees by $320 million and $327 million, respectively. At both December 31, 2022 and 2021, the G&P basis difference related to goodwill was $31 million. At both December 31, 2022 and 2021, the L&S basis difference related to goodwill was $167 million.

Related Party Agreements and Tr

Related Party Agreements and Transactions	12 Months Ended
	Dec. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	Related Party Agreements and Transactions MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below. MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products and other fees for storage capacity; operating and management fees; as well as reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under the marine transportation service agreement. In addition, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services type agreements as well as various other agreements as discussed below. The commercial agreements with MPC include: • MPLX has a fuels distribution agreement with MPC under which MPC pays MPLX a tiered monthly volume-based fee for marketing and selling MPC’s products. This agreement is subject to a minimum quarterly volume and has an initial term of 10 years, subject to a five • MPLX has various pipeline transportation agreements under which MPC pays MPLX fees for transporting crude and refined products on MPLX’s pipeline systems. These agreements are subject to minimum throughput volumes under which MPC will pay MPLX deficiency payments for any period in which they do not ship the minimum committed volume. Under certain agreements, deficiency payments can be applied as credits to future periods in which MPC ships volumes in excess of the minimum volume, subject to a limited period of time. These agreements are subject to various terms and renewal periods. • MPLX has a marine transportation agreement with an initial term of six years under which MPC pays MPLX fees for providing marine transportation of crude oil, feedstock and refined petroleum products, and related services. This agreement is subject to two automatic renewal periods of five years each. This agreement is currently in the first renewal term. • MPLX has a month-to-month trucking transportation services agreement under which MPC pays MPLX fees for gathering barrels and providing trucking, dispatch, delivery and data services. • MPLX has numerous storage services agreements governing storage services at various types of facilities including terminals, pipeline tank farms, caverns and refineries, under which MPC pays MPLX per-barrel fees for providing storage services. Some of these agreements provide MPC with exclusive access to storage at certain locations, such as storage located at MPC’s refineries or storage in certain caverns. Under these agreements, MPC pays MPLX a per-barrel fee for such storage capacity, regardless of whether MPC fully utilizes the available capacity. These agreements are subject to various terms and renewal periods. • MPLX has multiple terminal services agreements governing certain terminals under which MPC pays MPLX fees for terminal services. Under these agreements MPC pays MPLX agreed upon fees relating to MPC product receipts, deliveries and storage as well as any blending, additization, handling, transfers or other related charges. Many of these agreements are subject to minimum volume throughput commitments, or to various minimum commitments related to some or all terminal activities, under which MPC pays a deficiency payment for any period in which they do not meet the minimum commitment. Some of these agreements allow for deficiency payments to be applied as credits to a limited number of future periods with excess throughput volumes. These agreements are subject to various terms and renewal periods. • MPLX 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. The pricing structure under this agreement provides for a base volume subject to a base rate and incremental volumes subject to variable rates, which are calculated with reference to certain of our costs incurred as processor of the volumes. The pricing for both the base and incremental volumes are subject to revision each year. This agreement is subject to automatic three-month renewal periods. In many cases, agreements are location-based hybrid agreements, containing provisions relating to multiple of the types of agreements and services described above. Operating Agreements MPLX operates various pipelines owned by MPC under operating services agreements. Under these operating services agreements, MPLX receives an operating fee for operating the assets and is reimbursed for all direct and indirect costs associated with operating the assets. Most of these agreements are indexed for inflation. These agreements range from one Co-location Services Agreements MPLX is party to co-location services agreements with MPC’s refineries, under which MPC provides management, operational and other services to MPLX. MPLX pays MPC monthly fixed fees and direct reimbursements for such services calculated as set forth in the agreements. These agreements have initial terms of 50 years. Ground Lease Agreements MPLX is party to ground lease agreements with certain of MPC’s refineries under which MPLX is the lessee of certain sections of property which contain facilities owned by MPLX and are within the premises of MPC’s refineries. MPLX pays MPC monthly fixed fees under these ground leases. These agreements are subject to various terms. Marine Services Agreements with MPC MPLX has a management services agreement with MPC under which it provides management services to assist MPC in the oversight and management of the marine business. MPLX receives fixed annual fees for providing the required services, which are subject to predetermined annual escalation rates. This agreement is subject to an initial term of five years and automatically renews for one additional five Omnibus Agreements MPLX has omnibus agreements with MPC that address MPLX’s payment of fixed annual fees to MPC for the provision of executive management services by certain executive officers of the general partner and MPLX’s reimbursement of MPC for the provision of certain general and administrative services to it. They also provide for MPC’s indemnification to MPLX for certain matters, including environmental, title and tax matters; as well as our indemnification of MPC for certain matters under these agreements. Employee Services Agreements MPLX has various employee services agreements and secondment agreements with MPC under which MPLX reimburses MPC for employee benefit expenses, along with the provision of operational and management services in support of both our L&S and G&P segments’ operations. Related Party Loan MPLX is party to a loan agreement (the “MPC Loan Agreement”) with MPC. Under the terms of the MPC Loan Agreement, MPC extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC. 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 MPC Loan Agreement are scheduled to mature and become due and payable on July 31, 2024, provided that MPC 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 bore 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 17. The MPC Loan Agreement was amended effective January 1, 2023 to update the interest rate to one-month term SOFR adjusted upward by 0.10 percent plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 17. All other terms of the MPC Loan Agreement remain unchanged. Activity on the MPC Loan Agreement was as follows: (In millions, except %) December 31, 2022 December 31, 2021 Borrowings $ 2,989 $ 8,493 Weighted average interest rate of borrowings 1.50 % 1.34 % Repayments $ 4,439 $ 7,043 Outstanding balance at end of period $ — $ 1,450 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. Amounts earned under 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 years ended December 31, 2022, 2021 and 2020, these sales totaled $1,002 million, $811 million and $462 million, respectively. Related Party Expenses MPC charges MPLX for executive management services and certain general and administrative services provided to MPLX under the terms of our omnibus agreements (“Omnibus charges”) and for certain employee services provided to MPLX under employee services agreements (“ESA charges”). Omnibus charges and ESA charges are classified as Rental cost of sales - related parties, Purchases - related parties, or General and administrative expenses depending on the nature of the asset or activity with which the costs are associated. In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain rent and lease agreements with MPC. Starting in 2020, MPC advanced certain strategic priorities to lay a foundation for long-term success, including plans to optimize its assets and structurally lower costs in 2021 and beyond, which included an involuntary workforce reduction plan. The workforce reduction plan, together with employee reductions resulting from MPC's indefinite idling of its Martinez, California and Gallup, New Mexico refineries, affected approximately 2,050 employees. All of the employees that conduct MPLX’s business are directly employed by affiliates of MPC, and certain of those employees were affected by MPC’s workforce reductions. During 2020, MPLX reimbursed MPC for $37 million related to severance and employee benefits related expenses that MPC recorded in connection with its workforce reductions. These costs are shown on the Consolidated Statements of Income as Restructuring expenses. There were no similar costs in 2021 or 2022. For the years ended December 31, 2022, 2021 and 2020, General and administrative expenses incurred from MPC totaled $235 million, $250 million and $254 million, respectively. Some charges incurred under the omnibus and employee service agreements are related to engineering services and are associated with assets under construction. These charges are added to Property, plant and equipment, net on the Consolidated Balance Sheets. For 2022, 2021 and 2020, these charges totaled $70 million, $55 million and $97 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 (see Note 20 for additional information) and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts 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. December 31, (In millions) 2022 2021 Current assets - related parties Receivables $ 610 $ 555 Lease receivables 111 82 Prepaid 5 4 Other 3 3 Total 729 644 Noncurrent assets - related parties Long-term lease receivables 883 854 Right of use assets 228 229 Unguaranteed residual asset 87 47 Long-term receivables 27 31 Total 1,225 1,161 Current liabilities - related parties MPC loan agreement and other payables (1) 262 1,702 Deferred revenue 80 77 Operating lease liabilities 1 1 Total 343 1,780 Long-term liabilities - related parties Long-term operating lease liabilities 228 228 Long-term deferred revenue 110 74 Total $ 338 $ 302 (1) Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the MPC Loan Agreement. There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2022. Other Related Party Transactions From time to time, MPLX may also sell to or purchase from related parties, assets and inventory at the lesser of average unit cost or net realizable value. Sales to related parties for the years ended December 31, 2022, 2021 and 2020 were $25 million, $26 million and $10 million, respectively. Purchases from related parties for the year ended December 31, 2022 were $31 million and were immaterial for the years ended December 31, 2021 and 2020.

Equity

Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Equity	Equity Units Outstanding MPLX had 1,001,020,616 common units outstanding as of December 31, 2022. Of that number, 647,415,452 were owned by MPC, which also owns the non-economic GP Interest as described below. MPLX had 600,000 Series B preferred units outstanding as of December 31, 2022. The table below summarizes the changes in the number of units outstanding for the years ended December 31, 2020, 2021, and 2022: (In units) Total Common Units Balance at December 31, 2019 1,058,355,471 Unit-based compensation awards 478,438 Units redeemed in unit repurchase program (1,473,843) Wholesale Exchange (1) (18,582,088) Balance at December 31, 2020 1,038,777,978 Unit-based compensation awards 214,466 Conversion of Series A preferred units 93,108 Units redeemed in unit repurchase program (22,907,174) Balance at December 31, 2021 1,016,178,378 Unit-based compensation awards 190,529 Units redeemed in unit repurchase program (15,348,291) Balance at December 31, 2022 1,001,020,616 (1) In connection with the Wholesale Exchange as discussed in Note 4, MPLX redeemed 18,582,088 units from MPC in exchange for all of the outstanding membership interests in WRW. These units were cancelled by MPLX immediately following the transaction. 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, which was exhausted during the fourth quarter of 2022. 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. This unit repurchase authorization has no expiration date. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, accelerated unit repurchases, tender offers or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing 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. The table below summarizes the repurchases made under the unit repurchase program for the years ended December 31, 2022, 2021 and 2020: (In millions, except per unit data) 2022 2021 2020 Number of units repurchased 15 23 1 Cash paid for units repurchased (1) $ 491 $ 630 $ 33 Average cost per unit (1) $ 31.96 $ 27.52 $ 22.29 (1) Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period. As of December 31, 2022, we had $846 million available under our remaining unit repurchase authorization. Series B Preferred Units MPLX has 600,000 units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of MPLX at a price to the public of $1,000 per unit. The Series B preferred units are pari passu with the Series A preferred units with respect to distribution rights and rights upon liquidation. Distributions on the Series B preferred units are payable semi-annually in arrears on the 15th day, or the first business day thereafter, of February and August of each year up to and including February 15, 2023. The changes in the Series B preferred unit balance during 2022, 2021 and 2020 are included in the Consolidated Statements of Equity within Series B preferred units. On February 15, 2023, MPLX exercised its right to redeem all of the Series B preferred units. MPLX paid unitholders the Series B preferred unit redemption price of $1,000 per unit. Issuance of Additional Securities The Sixth Amended and Restated Agreement of Limited Partnership of MPLX LP, dated as of February 1, 2021 (“Partnership Agreement”), authorizes MPLX to issue an unlimited number of additional securities for the consideration and on the terms and conditions determined by the general partner without the approval of the unitholders. Cash Distributions Total distributions for the twelve months ended December 31, 2022, 2021 and 2020 are summarized in the table below. The 2021 period includes a supplemental distribution amount of $0.575 per common unit (the “Supplemental Distribution Amount”) related to the distribution declared for the third quarter of 2021, which was paid during the fourth quarter of 2021. 2022 2021 2020 Distributions per common unit $ 2.96 $ 3.36 $ 2.75 Additionally, 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 general, limited, and preferred unitholders is as follows for the years ended December 31, 2022, 2021 and 2020. The Partnership Agreement sets forth the calculation to be used to determine the amount and priority of cash distributions that the common unitholders and preferred unitholders will receive. 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. (In millions) 2022 2021 2020 Common and preferred unit distributions: Common unitholders, includes common units of general partner (1) $ 2,980 $ 3,432 $ 2,872 Series A preferred unit distributions (1) 88 100 81 Series B preferred unit distributions 41 41 41 Total cash distributions declared $ 3,109 $ 3,573 $ 2,994 (1) 2021 period includes the Supplemental Distribution Amount.

Net Income (Loss) Per Limited P

Net Income (Loss) Per Limited Partner Unit	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Net Income/(Loss) Per Limited Partner Unit Net income/(loss) per unit applicable to common limited partner units is computed by dividing net income/(loss) attributable to MPLX LP less income/(loss) allocated to participating securities by the weighted average number of common units outstanding. Classes of participating securities include common units, equity-based compensation awards, Series A preferred units and Series B preferred units. In 2022, 2021 and 2020, MPLX had dilutive potential common units consisting of certain equity-based compensation awards. Anti-dilutive potential common units omitted from the diluted earnings per unit calculation for the years ended December 31, 2022, 2021 and 2020 were less than 1 million. (In millions) 2022 2021 2020 Net income/(loss) attributable to MPLX LP (1) $ 3,944 $ 3,077 $ (720) Less: Distributions declared on Series A preferred units (2) 88 100 81 Distributions declared on Series B preferred units 41 41 41 Limited partners’ distributions declared on MPLX common units (including common units of general partner) (2) 2,980 3,432 2,872 Undistributed net income/(loss) attributable to MPLX LP $ 835 $ (496) $ (3,714) (1) The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information. (2) The year ended December 31, 2021 includes the Supplemental Distribution Amount. 2022 (In millions, except per unit data) Limited 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 $ 2,980 $ 88 $ 41 $ 3,109 Undistributed net income attributable to MPLX LP 811 24 — 835 Net income attributable to MPLX LP (1) $ 3,791 $ 112 $ 41 $ 3,944 Weighted average units outstanding: Basic 1,010 Diluted 1,010 Net income attributable to MPLX LP per limited partner unit: Basic $ 3.75 Diluted $ 3.75 (1) The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information. 2021 (In millions, except per unit data) Limited 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) $ 3,432 $ 100 $ 41 $ 3,573 Undistributed net loss attributable to MPLX LP (496) — — (496) Net income attributable to MPLX LP $ 2,936 $ 100 $ 41 $ 3,077 Weighted average units outstanding: Basic 1,027 Diluted 1,027 Net income attributable to MPLX LP per limited partner unit: Basic $ 2.86 Diluted $ 2.86 (1) Includes the Supplemental Distribution Amount. 2020 (In millions, except per unit data) Limited Series A Preferred Units Series B Preferred Units Total Basic and diluted net loss attributable to MPLX LP per unit: Net (loss)/income attributable to MPLX LP: Distribution declared $ 2,872 $ 81 $ 41 $ 2,994 Undistributed net loss attributable to MPLX LP (3,714) — — (3,714) Net (loss)/income attributable to MPLX LP $ (842) $ 81 $ 41 $ (720) Weighted average units outstanding: Basic 1,051 Diluted 1,051 Net loss attributable to MPLX LP per limited partner unit: Basic $ (0.80) Diluted $ (0.80)

Redeemable Preferred Units

Redeemable Preferred Units	12 Months Ended
	Dec. 31, 2022
Redeemable Preferred Units Disclosure [Abstract]
Redeemable Preferred Units	Series A Preferred Units Private Placement of Preferred Units On May 13, 2016, MPLX completed the private placement of approximately 30.8 million 6.5 percent Series A Convertible preferred units for a cash purchase price of $32.50 per unit. The aggregate net proceeds of approximately $984 million from the sale of the Series A preferred units were used for capital expenditures, repayment of debt and general business purposes. Preferred Unit Distribution Rights The Series A preferred units rank senior to all common units and pari passu with all Series B preferred units with respect to distributions and rights upon liquidation. The holders of the Series A preferred units are entitled to receive, when and if declared by the board, a quarterly distribution equal to the greater of $0.528125 per unit or the amount of distributions they would have received on an as converted basis, including any supplemental distributions made to common unitholders. On January 25, 2023, MPLX declared a quarterly cash distribution of $0.7750 per common unit for the fourth quarter of 2022. Holders of the Series A preferred units received the common unit rate in lieu of the lower $0.528125 base amount. The holders may convert their Series A preferred units into common units at any time, in full or in part, subject to minimum conversion amounts and conditions. After the fourth anniversary of the issuance date, MPLX may convert the Series A preferred units into common units at any time, in whole or in part, subject to certain minimum conversion amounts and conditions, if the closing price of MPLX common units is greater than $48.75 for the 20-day trading period immediately preceding the conversion notice date. The conversion rate for the Series A preferred units shall be the quotient of (a) the sum of (i) $32.50, plus (ii) any unpaid cash distributions on the applicable preferred unit, divided by (b) $32.50, subject to adjustment for unit distributions, unit splits and similar transactions. The holders of the Series A preferred units are entitled to vote on an as-converted basis with the common unitholders and have certain other class voting rights with respect to any amendment to the MPLX partnership agreement that would adversely affect any rights, preferences or privileges of the preferred units. In addition, upon certain events involving a change of control, the holders of preferred units may elect, among other potential elections, to convert their Series A preferred units to common units at the then applicable change of control conversion rate. Preferred Units Outstanding During the year ended December 31, 2021, certain Series A preferred unitholders exercised their rights to convert their Series A preferred units into 93,108 common units. As a result of these transactions, approximately 29.5 million Series A preferred units remain outstanding as of December 31, 2022. Financial Statement Presentation The Series A preferred units are considered redeemable securities under GAAP due to the existence of redemption provisions upon a deemed liquidation event, which is outside MPLX’s control. Therefore, they are presented as temporary equity in the mezzanine section of the Consolidated Balance Sheets. The Series A preferred units have been recorded at their issuance date fair value, net of issuance costs. Income allocations increase the carrying value and declared distributions decrease the carrying value of the Series A preferred units. As the Series A preferred units are not currently redeemable and not probable of becoming redeemable, adjustment to the initial carrying amount is not necessary and would only be required if it becomes probable that the Series A preferred units would become redeemable. For a summary of changes in the redeemable preferred balance for the years ended December 31, 2022, 2021 and 2020, see the Consolidated Statements of Equity.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2022
Segment Reporting [Abstract]
Segment Information	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, other hydrocarbon-based products and renewables. 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) income/(loss) from equity method investments; (iv) distributions and adjustments related to equity method investments; (v) gain on sales-type leases; (vi) impairment expense; (vii) restructuring expenses (viii) noncontrolling interests; and (ix) 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, restructuring expenses, capital expenditures and investments in unconsolidated affiliates as well as total assets for our reportable segments: (In millions) 2022 2021 2020 L&S Service revenue $ 4,057 $ 3,918 $ 3,889 Rental income 803 772 985 Product related revenue 19 14 51 Sales-type lease revenue 465 435 152 Income from equity method investments 267 153 154 Other income 57 61 54 Total segment revenues and other income (1) 5,668 5,353 5,285 Segment Adjusted EBITDA (2) 3,818 3,681 3,488 Restructuring expenses — — 29 Capital expenditures 325 316 498 Investments in unconsolidated affiliates 97 33 141 G&P Service revenue 2,056 2,023 2,088 Rental income 287 347 365 Product related revenue 2,792 2,066 868 Sales-type lease revenue 62 — — Income/(loss) from equity method investments 209 168 (1,090) Other income (3) 539 70 53 Total segment revenues and other income (1) 5,945 4,674 2,284 Segment Adjusted EBITDA (2) 1,957 1,879 1,723 Restructuring expenses — — 8 Capital expenditures 528 224 441 Investments in unconsolidated affiliates $ 120 $ 118 $ 125 (1) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $644 million, $503 million and $567 million for the years ended December 31, 2022, 2021 and 2020, respectively. Third party revenues for the G&P segment were $5,678 million, $4,463 million and $2,088 million for the years ended December 31, 2022, 2021 and 2020, respectively. (2) See below for the reconciliation from Segment Adjusted EBITDA to Net income/(loss). (3) Includes a $509 million non-cash gain on a lease reclassification for the year ended December 31, 2022. See Note 20 in the Consolidated Financial Statements for additional information. The table below provides a reconciliation between Net income/(loss) and Segment Adjusted EBITDA. (In millions) 2022 2021 2020 Reconciliation to Net income/(loss): L&S Segment Adjusted EBITDA $ 3,818 $ 3,681 $ 3,488 G&P Segment Adjusted EBITDA 1,957 1,879 1,723 Total reportable segments 5,775 5,560 5,211 Depreciation and amortization (1) (1,230) (1,287) (1,377) Interest and other financial costs (925) (879) (896) Income/(loss) from equity method investments 476 321 (936) Distributions/adjustments related to equity method investments (652) (537) (499) Gain on sales-type leases 509 — — Impairment expense — (42) (2,165) Restructuring expenses — — (37) Adjusted EBITDA attributable to noncontrolling interests 38 39 37 Other (2) (13) (63) (25) Net income/(loss) $ 3,978 $ 3,112 $ (687) (1) Depreciation and amortization attributable to L&S was $515 million, $546 million and $633 million for the years ended December 31, 2022, 2021 and 2020, respectively. Depreciation and amortization attributable to G&P was $715 million, $741 million and $744 million for the years ended December 31, 2022, 2021 and 2020, respectively. (2) Includes unrealized derivative gain/(loss), non-cash equity-based compensation, provision for income taxes, and other miscellaneous items.

Major Customers and Concentrati

Major Customers and Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2022
Risks and Uncertainties [Abstract]
Major Customers and Concentration of Credit Risk	Major Customers and Concentration of Credit Risk The table below shows, by segment, the percentage of total revenues and other income with MPC which is our most significant customer and our largest concentration of credit risk. 2022 2021 2020 Total revenues and other income (1)(2) L&S 88 % 90 % 89 % G&P 4 % 3 % 4 % Total 47 % 50 % 55 % (1) The percent calculations exclude losses attributable to the impairment of equity method investments. (2) The percent calculations for the year ended December 31, 2022 exclude a $509 million non-cash gain on a lease reclassification. MPLX has a concentration of trade receivables due from customers in the same industry: MPC, integrated oil companies, natural gas exploration and production companies, independent refining companies and other pipeline companies. These concentrations of customers may impact MPLX’s overall exposure to credit risk as they may be similarly affected by changes in economic, regulatory and other factors. MPLX manages its exposure to credit risk through credit analysis, credit limit approvals and monitoring procedures; and for certain transactions, it may request letters of credit, prepayments or guarantees.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2022
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: December 31, (In millions) 2022 2021 NGLs $ 6 $ 12 Line fill 16 23 Spare parts, materials and supplies 126 107 Total inventories $ 148 $ 142

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 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: Estimated December 31, (In millions) 2022 2021 L&S Pipelines 15-50 years $ 6,323 $ 6,299 Refining logistics 15-20 years 1,710 1,650 Terminals 15-40 years 1,618 1,655 Marine 15-20 years 1,000 965 Land, building and other 5-60 years 1,585 1,589 Construction-in-progress 180 213 Total L&S property, plant and equipment 12,416 12,371 G&P Gathering and transportation 5-40 years 6,781 7,668 Processing and fractionation 10-40 years 5,928 5,795 Land, building and other 5-40 years 511 514 Construction-in-progress 275 198 Total G&P property, plant and equipment 13,495 14,175 Total property, plant and equipment 25,911 26,546 Less accumulated depreciation (1) 7,063 6,504 Property, plant and equipment, net $ 18,848 $ 20,042 (1) Includes property, plant and equipment impairment charges recorded during the respective period, as discussed below. We capitalize interest as part of the cost of major projects during the construction period. Capitalized interest totaled $9 million, $14 million and $39 million as of the years ended December 31, 2022, 2021 and 2020, respectively. 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. 174 million

Goodwill and Intangibles

Goodwill and Intangibles	12 Months Ended
	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	Goodwill and Intangibles Goodwill MPLX annually evaluates goodwill for impairment as of November 30, as well as whenever events or changes in circumstances indicate it is more likely than not that the fair value of a reporting unit with goodwill is less than its carrying amount. Our reporting units are one level below our operating segments and are determined based on the way in which segment management operates and reviews each operating segment. We have five reporting units, three of which have goodwill allocated to them. For the annual impairment assessment as of November 30, 2022, management performed only a qualitative assessment for two reporting units as we determined it was more likely than not that the fair values of the reporting units exceeded their carrying values. The fair value of the crude gathering reporting unit for which a quantitative assessment was performed was determined based on applying both a discounted cash flow, or income approach, as well as a market approach which resulted in the fair value of the reporting unit exceeding its carrying value by greater than 10 percent. The significant assumptions used to develop the estimate of the fair value under the discounted cash flow method included management’s best estimates of the discount rate of 10.1 percent as well as estimates of future cash flows, which are impacted primarily by producer customers’ development plans, which impact future volumes and capital requirements. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the annual goodwill impairment test will prove to be an accurate prediction of the future. The fair value measurements for the individual reporting units represent Level 3 measurements. Total goodwill at December 31, 2022 was $7,645 million and no impairment was recorded as a result of our November 30, 2022 annual goodwill impairment analysis. During the first quarter of 2020, we determined that an interim impairment analysis of the goodwill recorded was necessary based on consideration of a number of first quarter events and circumstances. Our producer customers in our Eastern G&P region reduced production forecasts and drilling activity in response to the global economic downturn. Additionally, a decline in NGL prices impacted our future revenue forecast. After performing our evaluations related to the interim impairment of goodwill during the first quarter of 2020, we recorded an impairment of $1,814 million within the Eastern G&P reporting unit, which was recorded to “Impairment expense” on the Consolidated Statements of Income. The impairment was primarily driven by additional guidance related to the slowing of drilling activity, which reduced production growth forecasts from our producer customers. The interim impairment assessment of the remaining reporting units with goodwill resulted in the fair value of the reporting units exceeding their carrying value. The fair value of our reporting units was determined using the same methodology and significant assumptions described above and included management’s best estimates of the discount rate, which ranged from 9.5 percent to 11.5 percent. The changes in carrying amount of goodwill were as follows for the periods presented: (In millions) L&S G&P Total Gross goodwill as of December 31, 2020 $ 7,657 $ 3,141 $ 10,798 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2020 7,657 — 7,657 Impairment losses — — — Balance as of December 31, 2021 7,657 — 7,657 Impairment losses — — — Disposal of assets (12) — (12) Balance as of December 31, 2022 7,645 — 7,645 Gross goodwill as of December 31, 2022 7,645 3,141 10,786 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2022 $ 7,645 $ — $ 7,645 Intangible Assets MPLX’s intangible assets are comprised of customer contracts and relationships. Gross intangible assets with accumulated amortization as of December 31, 2022 and 2021 is shown below: December 31, 2022 December 31, 2021 (In millions) Useful Life Gross Accumulated Amortization (1) Net Gross Accumulated Amortization (1) Net L&S 6 - 8 years $ 283 $ (153) $ 130 $ 283 $ (117) $ 166 G&P 6 - 25 years 1,288 (713) 575 1,288 (623) 665 $ 1,571 $ (866) $ 705 $ 1,571 $ (740) $ 831 (1) Amortization expense attributable to the L&S segment for both years ended December 31, 2022 and 2021 was $36 million. Amortization expense attributable to the G&P segment for the years ended December 31, 2022 and 2021 was $90 million and $92 million, respectively. During the first quarter of 2020, we also determined that an impairment analysis of intangibles within our Western G&P reporting unit was necessary. See Note 13 for additional information regarding our assessment around the Western G&P reporting unit, and more specifically our East Texas G&P asset group. The fair value of the intangibles in our East Texas G&P asset group were determined based on applying the multi-period excess earnings method, which is an income approach. Key assumptions included management’s best estimates of the expected future cash flows from existing customers, customer attrition rates and the discount rate. After performing our evaluations related to the impairment of intangible assets associated with our East Texas G&P asset group during the first quarter of 2020, we recorded an impairment of $177 million to Impairment expense Estimated future amortization expense related to the intangible assets at December 31, 2022 is as follows: (In millions) 2023 $ 127 2024 127 2025 113 2026 104 2027 76 2028 and thereafter 158 Total $ 705

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 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 16. Level 3 instruments relate to a derivative liability for a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments uses significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.68 to $1.62 per gallon with a weighted average of $0.84 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of December 31, 2022 or December 31, 2021. Changes in Level 3 Fair Value Measurements The following table is a reconciliation of the net beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. (In millions) 2022 2021 Beginning balance $ (108) $ (63) Unrealized and realized gain/(loss) included in net income (1) 35 (59) Settlements 12 14 Ending balance (61) (108) The amount of total gain/(loss) for the period included in net income attributable to the change in unrealized gain or loss relating to liabilities still held at end of period $ 33 $ (47) (1) Gain/(loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs on 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 20. 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. The fair value of MPLX’s debt is estimated based on recent market non-binding indicative quotes. The debt fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs: December 31, 2022 2021 (In millions) Fair Value Carrying Value Fair Value Carrying Value Outstanding debt (1) $ 18,095 $ 19,905 $ 20,779 $ 18,664 (1) Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments For the years 2022, 2021 and 2020, 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 As of December 31, 2022 and 2021, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below: December 31, (In millions) 2022 2021 Derivative contracts not designated as hedging instruments and their balance sheet location Asset Liability Asset Liability Commodity contracts (1) Other current assets / Other current liabilities $ — $ 10 $ — $ 15 Other noncurrent assets / Other long-term liabilities — 51 — 93 Total $ — $ 61 $ — $ 108 (1) Includes the embedded derivative in the commodity contract discussed above. The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below: (In millions) 2022 2021 2020 Purchased product costs Realized loss $ (12) $ (14) $ (6) Unrealized gain/(loss) 47 (45) (3) Purchased product cost derivative gain/(loss) $ 35 $ (59) $ (9)

Debt

Debt	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Debt	Debt MPLX’s outstanding borrowings at December 31, 2022 and 2021 consisted of the following: December 31, (In millions) 2022 2021 MPLX LP: Bank revolving credit facility $ — $ 300 3.500% senior notes due December 1, 2022 — 486 3.375% senior notes due March 15, 2023 — 500 4.500% senior notes due July 15, 2023 989 989 4.875% senior notes due December 1, 2024 1,149 1,149 4.000% senior notes due February 15, 2025 500 500 4.875% senior notes due June 1, 2025 1,189 1,189 1.750% senior notes due March 1, 2026 1,500 1,500 4.125% senior notes due March 1, 2027 1,250 1,250 4.250% senior notes due December 1, 2027 732 732 4.000% senior notes due March 15, 2028 1,250 1,250 4.800% senior notes due February 15, 2029 750 750 2.650% senior notes due August 15, 2030 1,500 1,500 4.950% senior notes due September 1, 2032 1,000 — 4.500% senior notes due April 15, 2038 1,750 1,750 5.200% senior notes due March 1, 2047 1,000 1,000 5.200% senior notes due December 1, 2047 487 487 4.700% senior notes due April 15, 2048 1,500 1,500 5.500% senior notes due February 15, 2049 1,500 1,500 4.950% senior notes due March 14, 2052 1,500 — 4.900% senior notes due April 15, 2058 500 500 Consolidated subsidiaries: MarkWest - 4.500% - 4.875% senior notes, due 2023-2025 23 23 ANDX - 3.500% - 5.200% senior notes, due 2027-2047 31 45 Financing lease obligations (1) 8 9 Total 20,108 18,909 Unamortized debt issuance costs (117) (102) Unamortized discount (195) (236) Amounts due within one year (988) (499) Total long-term debt due after one year $ 18,808 $ 18,072 (1) See Note 20 for lease information. The following table shows five years of scheduled debt payments, including payments on finance lease obligations, as of December 31, 2022: (In millions) 2023 $ 1,002 2024 1,152 2025 1,701 2026 1,501 2027 $ 2,001 Credit Agreements MPLX 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 July 7, 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. The borrowing capacity under the MPLX Credit Agreement may be increased by up to an additional $1.0 billion, subject to certain conditions, including the consent of lenders whose commitments would increase. In addition, the maturity date may be extended, for up to two additional one year periods, subject to, among other conditions, the approval of lenders holding the majority of the commitments then outstanding, provided that the commitments of any non-consenting lenders will terminate on the then-effective maturity date. MPLX is charged various fees and expenses in connection with the agreement, including administrative agent fees, commitment fees on the unused portion of the facility and fees with respect to issued and outstanding letters of credit. The applicable margins to the benchmark interest rates and certain fees fluctuate based on the credit ratings in effect from time to time on MPLX’s long-term debt. The MPLX Credit Agreement contains certain representations and warranties, affirmative and restrictive covenants and events of default that MPLX considers to be usual and customary for an agreement of this type, including a financial covenant that requires MPLX to maintain a ratio of Consolidated Total Debt as of the end of each fiscal quarter to Consolidated EBITDA (both as defined in the MPLX Credit Agreement) for the prior four fiscal quarters of no greater than 5.0 to 1.0 (or 5.5 to 1.0 for up to two fiscal quarters following certain acquisitions). Consolidated EBITDA is subject to adjustments, including for certain acquisitions and dispositions completed and capital projects undertaken during the relevant period. Other covenants restrict MPLX and/or certain of its subsidiaries from incurring debt, creating liens on our assets and entering into transactions with affiliates. As of December 31, 2022, MPLX was in compliance with the covenants contained in the MPLX Credit Agreement. Activity on the new and previous MPLX Credit Agreement was as follows: (In millions, except %) December 31, 2022 December 31, 2021 Borrowings $ 900 $ 4,175 Weighted average interest rate of borrowings 1.45 % 1.34 % Repayments $ 1,200 $ 4,050 Outstanding balance at end of period $ — $ 300 Letters of credit outstanding $ 0.2 $ 0.2 Total remaining availability on facility $ 2,000 $ 3,200 Percent of borrowing capacity available 100 % 91 % Senior Notes Interest on each series of MPLX LP, MarkWest and ANDX senior notes is payable semi-annually in arrears, according to the table below. Senior Notes Interest payable semi-annually in arrears 4.500% senior notes due July 15, 2023 January 15 th and July 15 th 4.875% senior notes due December 1, 2024 June 1 st and December 1 st 4.000% senior notes due February 15, 2025 February 15 th and August 15 th 4.875% senior notes due June 1, 2025 June 1 st and December 1 st 1.750% senior notes due March 1, 2026 March 1 st and September 1 st 4.125% senior notes due March 1, 2027 March 1 st and September 1 st 4.250% senior notes due December 1, 2027 June 1 st and December 1 st 4.000% senior notes due March 15, 2028 March 15 th and September 15 th 4.800% senior notes due February 15, 2029 February 15 th and August 15 th 2.650% senior notes due August 15, 2030 February 15 th and August 15 th 4.950% senior notes due September 1, 2032 March 1 st and September 1 st 4.500% senior notes due April 15, 2038 April 15 th and October 15 th 5.200% senior notes due March 1, 2047 March 1 st and September 1 st 5.200% senior notes due December 1, 2047 June 1 st and December 1 st 4.700% senior notes due April 15, 2048 April 15 th and October 15 th 5.500% senior notes due February 15, 2049 February 15 th and August 15 th 4.950% senior notes due March 14, 2052 March 14 th and September 14 th 4.900% senior notes due April 15, 2058 April 15 th and October 15 th On February 9, 2023, MPLX issued $1.6 billion aggregate principal amount of notes, consisting of $1.1 billion principal amount of 5.00 percent senior notes due 2033 (the “2033 Senior Notes”) and $500 million principal amount of 5.65 percent senior notes due 2053 (the “2053 Senior Notes”). The 2033 Senior Notes were offered at a price to the public of 99.170 percent of par with interest payable semi-annually in arrears, commencing on September 1, 2023. The 2053 Senior Notes were offered at a price to the public of 99.536 percent of par with interest payable semi-annually in arrears, commencing on September 1, 2023. MPLX used $600 million of the net proceeds to redeem all of the outstanding Series B preferred units. We also provided notice to redeem all of MPLX’s and MarkWest’s $1.0 billion aggregate principal amount of 4.50 percent senior notes due July 2023. On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes in a public offering due March 2052 (the “2052 Senior Notes”). The 2052 Senior Notes were offered at a price to the public of 98.982 percent of par with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the MPC Intercompany Loan Agreement and the MPLX Credit Agreement as well as for general partnership purposes. 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 of par 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 100.101 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. On January 15, 2021, MPLX redeemed all of the $750 million outstanding aggregate principal amount of 5.250 percent senior notes, due January 15, 2025, including approximately $42 million aggregate principal amount of senior notes issued by ANDX, at a price equal to 102.625 percent of the principal amount. The payment of $20 million related to the note premium, offset by the immediate expense recognition of $12 million of unamortized debt premium and issuance costs, resulted in a loss on extinguishment of debt of $8 million that is included on the Consolidated Statements of Income as Other financial costs. Subordination of Senior Notes The MPLX senior notes are direct, unsecured unsubordinated obligations of MPLX LP. As such, they rank equally in right of payment with all of MPLX LP’s other unsubordinated debt and are not guaranteed by any of MPLX LP’s subsidiaries. The MPLX notes are effectively junior to MPLX LP’s secured indebtedness, if any, to the extent of the value of the relevant collateral. The MPLX notes are not obligations of any of MPLX’s subsidiaries and are effectively subordinated to all indebtedness and other obligations of such subsidiaries. The MPLX notes may be redeemed, in whole or part, at any time at the option of MPLX at a redemption price specified in the indenture governing the applicable notes, plus accrued and unpaid interest to the redemption date. The indenture governing the MPLX senior notes does not limit the amount of debt that MPLX may issue under the indenture, nor the amount of other debt that MPLX or any of its subsidiaries may issue or guaranty. The ANDX senior notes are non-recourse to MPLX and its subsidiaries other than ANDX, the general partner of ANDX and other subsidiaries, if any, of ANDX that are a co-issuer or guarantor of the ANDX senior notes. The MarkWest senior notes are non-recourse to MPLX and its subsidiaries other than MarkWest, the general partner of MarkWest and other subsidiaries, if any, of MarkWest that are a co-issuer or guarantor of the MarkWest senior notes.

Revenue

Revenue	12 Months Ended
	Dec. 31, 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 years ended December 31, 2022, 2021 and 2020: 2022 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 320 $ 2,039 $ 2,359 Service revenue - related parties 3,737 17 3,754 Service revenue - product related — 394 394 Product sales 6 2,213 2,219 Product sales - related parties 13 185 198 Total revenues from contracts with customers $ 4,076 $ 4,848 8,924 Non-ASC 606 revenue (1) 2,689 Total revenues and other income $ 11,613 2021 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 310 $ 2,003 $ 2,313 Service revenue - related parties 3,608 20 3,628 Service revenue - product related — 345 345 Product sales 4 1,586 1,590 Product sales - related parties 10 135 145 Total revenues from contracts with customers $ 3,932 $ 4,089 8,021 Non-ASC 606 revenue (1) 2,006 Total revenues and other income $ 10,027 2020 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 333 $ 2,064 $ 2,397 Service revenue - related parties 3,556 24 3,580 Service revenue - product related — 155 155 Product sales 39 597 636 Product sales - related parties 12 116 128 Total revenues from contracts with customers $ 3,940 $ 2,956 6,896 Non-ASC 606 revenue (1) 673 Total revenues and other income $ 7,569 (1) Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income/(loss) from equity method investments, and other income. Contract Balances Contract assets typically relate to deficiency payments related to minimum volume commitments and aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer. Contract assets are included in Other current assets and Other noncurrent assets on the Consolidated Balance Sheets. Contract liabilities, which we present 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 for the years ended December 31, 2022 and 2021: (In millions) Balance at Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 25 $ (4) $ — $ 21 Long-term contract assets 2 (1) — 1 Deferred revenue 56 41 (40) 57 Deferred revenue - related parties 60 109 (106) 63 Long-term deferred revenue 135 81 — 216 Long-term deferred revenue - related parties 31 (6) — 25 Long-term contract liabilities $ 5 $ (3) $ — $ 2 (In millions) Balance at Additions/ (Deletions) Revenue Recognized(1) Balance at Contract assets $ 40 $ (15) $ — $ 25 Long-term contract assets 2 — — 2 Deferred revenue 37 56 (37) 56 Deferred revenue - related parties 91 75 (106) 60 Long-term deferred revenue 119 16 — 135 Long-term deferred revenue - related parties 48 (17) — 31 Long-term contract liabilities $ 6 $ (1) $ — $ 5 (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 December 31, 2022, unsatisfied performance obligations included in the Consolidated Balance Sheets are $360 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. Additionally, we do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less. (In millions) 2023 $ 1,844 2024 1,717 2025 1,634 2026 1,471 2027 1,330 2028 and thereafter 733 Total revenue on remaining performance obligations (1)(2)(3) $ 8,729 (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.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information (In millions) 2022 2021 2020 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 813 $ 812 $ 821 Income taxes paid 3 4 2 Cash paid for amounts included in the measurement of lease liabilities Payments on operating leases 73 79 87 Interest payment under finance lease obligations — — 1 Net cash provided by financing activities included: Principal payments under finance lease obligations 2 2 9 Non-cash investing and financing activities: Net transfers of property, plant and equipment (to)/from materials and supplies inventories (1) 1 — ROU assets obtained in exchange for new operating lease obligations 78 20 17 ROU assets obtained in exchange for new finance lease obligations 1 — 1 Fair value of common units redeemed for Wholesale Exchange — — 340 The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that did not affect cash. The following is a reconciliation of additions to property, plant and equipment to total capital expenditure: (In millions) 2022 2021 2020 Additions to property, plant and equipment $ 806 $ 529 $ 1,183 Increase/(decrease) in capital accruals 47 11 (244) Total capital expenditures $ 853 $ 540 $ 939

Leases Leases (Notes)

Leases Leases (Notes)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Lessee, Operating Leases	Lessee We lease a wide variety of facilities and equipment under leases from third parties, including land and building space, office and field equipment, storage facilities and transportation equipment, while our related party leases primarily relate to ground leases associated with our refining logistics assets. Our remaining lease terms range from less than one one The components of lease cost were as follows: 2022 2021 2020 (In millions) Related Party Third Related Third Related Third Components of lease costs: Operating lease costs $ 15 $ 61 $ 15 $ 71 $ 14 $ 78 Finance lease cost: Amortization of ROU assets — 1 — 2 — 3 Interest on lease liabilities — 1 — 1 — 1 Total finance lease cost — 2 — 3 — 4 Variable lease cost 2 16 — 15 1 10 Short-term lease cost — 45 — 31 — 52 Total lease cost $ 17 $ 124 $ 15 $ 120 $ 15 $ 144 Supplemental balance sheet data related to leases were as follows: December 31, 2022 December 31, 2021 (In millions, except % and years) Related Party Third Party Related Party Third Party Operating leases Assets Right of use assets $ 228 $ 283 $ 229 $ 268 Liabilities Operating lease liabilities 1 46 1 59 Long-term operating lease liabilities 228 230 228 205 Total operating lease liabilities $ 229 $ 276 $ 229 $ 264 Weighted average remaining lease term 44.2 years 9.2 years 45.2 years 8.3 years Weighted average discount rate 5.8 % 4.1 % 5.8 % 4.1 % Finance leases Assets Property, plant and equipment, gross $ 11 $ 11 Less: Accumulated depreciation 4 4 Property, plant and equipment, net 7 7 Liabilities Long-term debt due within one year 1 2 Long-term debt 7 7 Total finance lease liabilities $ 8 $ 9 Weighted average remaining lease term 18.4 years 19.4 years Weighted average discount rate 6.0 % 6.0 % As of December 31, 2022, maturities of lease liabilities for operating lease obligations and finance lease obligations having initial or remaining non-cancellable lease terms in excess of one year are as follows: (In millions) Related Party Operating Third Party Operating Finance 2023 $ 15 $ 56 $ 2 2024 15 46 2 2025 14 34 1 2026 14 30 1 2027 14 29 1 2028 and thereafter 561 135 7 Gross lease payments 633 330 14 Less: Imputed interest 404 54 6 Total lease liabilities $ 229 $ 276 $ 8
Lessee, Finance Leases	Lessee We lease a wide variety of facilities and equipment under leases from third parties, including land and building space, office and field equipment, storage facilities and transportation equipment, while our related party leases primarily relate to ground leases associated with our refining logistics assets. Our remaining lease terms range from less than one one The components of lease cost were as follows: 2022 2021 2020 (In millions) Related Party Third Related Third Related Third Components of lease costs: Operating lease costs $ 15 $ 61 $ 15 $ 71 $ 14 $ 78 Finance lease cost: Amortization of ROU assets — 1 — 2 — 3 Interest on lease liabilities — 1 — 1 — 1 Total finance lease cost — 2 — 3 — 4 Variable lease cost 2 16 — 15 1 10 Short-term lease cost — 45 — 31 — 52 Total lease cost $ 17 $ 124 $ 15 $ 120 $ 15 $ 144 Supplemental balance sheet data related to leases were as follows: December 31, 2022 December 31, 2021 (In millions, except % and years) Related Party Third Party Related Party Third Party Operating leases Assets Right of use assets $ 228 $ 283 $ 229 $ 268 Liabilities Operating lease liabilities 1 46 1 59 Long-term operating lease liabilities 228 230 228 205 Total operating lease liabilities $ 229 $ 276 $ 229 $ 264 Weighted average remaining lease term 44.2 years 9.2 years 45.2 years 8.3 years Weighted average discount rate 5.8 % 4.1 % 5.8 % 4.1 % Finance leases Assets Property, plant and equipment, gross $ 11 $ 11 Less: Accumulated depreciation 4 4 Property, plant and equipment, net 7 7 Liabilities Long-term debt due within one year 1 2 Long-term debt 7 7 Total finance lease liabilities $ 8 $ 9 Weighted average remaining lease term 18.4 years 19.4 years Weighted average discount rate 6.0 % 6.0 % As of December 31, 2022, maturities of lease liabilities for operating lease obligations and finance lease obligations having initial or remaining non-cancellable lease terms in excess of one year are as follows: (In millions) Related Party Operating Third Party Operating Finance 2023 $ 15 $ 56 $ 2 2024 15 46 2 2025 14 34 1 2026 14 30 1 2027 14 29 1 2028 and thereafter 561 135 7 Gross lease payments 633 330 14 Less: Imputed interest 404 54 6 Total lease liabilities $ 229 $ 276 $ 8
Lessor, Operating Leases	Lessor Based on the terms of fee-based transportation and storage services agreements with MPC and third parties, MPLX is considered to be the lessor under several operating lease arrangements in accordance with GAAP. These agreements have remaining terms ranging from less than one year to 10 years with renewal options ranging from one year to five years, and some agreements having multiple renewal options. We are also considered to be the lessor under several operating lease agreements related to certain fee-based natural gas transportation and processing agreements in the Marcellus and Southern Appalachia region. The primary term of these agreements expire between 2026 and 2036, however, these contracts either have renewal options or will continue thereafter on a year-to-year basis until terminated by either party. Lease revenues included on the Consolidated Statements of Income during 2022, 2021 and 2020 were as follows: 2022 2021 2020 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 763 $ 327 $ 743 $ 376 $ 952 $ 398 Sales-type leases: Interest income (Sales-type rental revenue- fixed minimum) 447 46 431 — 151 — Interest income (Revenue from variable lease payments) 18 16 4 — 1 — Sales-type lease revenue $ 465 $ 62 $ 435 $ — $ 152 $ — MPLX did not elect to use the practical expedient to combine lease and non-lease components for lessor arrangements. The tables below represent the portion of the contract allocated to the lease component based on relative standalone selling price. We elected the practical expedient to carry forward historical classification conclusions until a modification of an existing agreement occurs. Once a modification occurs, the amended agreement is required to be assessed under ASC 842, to determine whether a reclassification of the lease is required. 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. Additionally, during the twelve months ended December 31, 2022, 2021 and 2020, we executed amendments to certain related party storage, transportation and terminal service agreements between MPLX and MPC to provide for reimbursements for projects, changes to minimum volume commitments or to extend the term of the agreement. The changes required the embedded leases within these agreements to be reassessed under ASC 842. As a result of these lease assessments, certain leases were reclassified from an operating lease to a sales-type lease. Accordingly, the underlying property, plant and equipment, net, and associated deferred revenue, if any, were derecognized and 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 respective periods. 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. 2022 2021 2020 (In millions) Related Party (1) Third Party (2) Related Party (1) Third Party Related Party (1) Third Party Lease receivables $ 87 $ 914 $ 519 $ — $ 370 $ — Unguaranteed residual assets 6 63 14 — 10 — Property, plant and equipment, net (50) (745) (421) — (171) — Deferred revenue — 277 — — — — Amount recognized on commencement date $ 43 $ 509 $ 112 $ — $ 209 $ — (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. The following is a schedule of minimum future rental revenue on the non-cancellable operating leases as of December 31, 2022: (In millions) Related Party Third Party Total 2023 $ 627 $ 97 $ 724 2024 569 95 664 2025 546 64 610 2026 446 37 483 2027 330 16 346 2028 and thereafter 149 21 170 Total minimum future rentals $ 2,667 $ 330 $ 2,997 Annual minimum undiscounted lease payment receipts under our sales-type leases were as follows as of December 31, 2022: (In millions) Related Party Third Party Total 2023 $ 489 $ 169 $ 658 2024 489 156 645 2025 489 146 635 2026 459 137 596 2027 357 128 485 2028 and thereafter 214 970 1,184 Total minimum future rentals 2,497 1,706 4,203 Less: present value discount 1,503 765 2,268 Lease receivable (1) $ 994 941 1,935 Current lease receivables (2) 111 98 209 Long-term lease receivables (3) 883 843 1,726 Unguaranteed residual assets (3) 87 66 153 Total sales-type lease assets $ 1,081 $ 1,007 $ 2,088 (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. The following schedule summarizes MPLX’s investment in assets held under operating lease by major classes as of December 31, 2022 and 2021: December 31, (In millions) 2022 2021 Pipelines $ 670 $ 953 Refining logistics 1,310 1,146 Terminals 1,241 1,290 Marine 126 129 Gathering and transportation 94 991 Processing and fractionation 973 867 Land, building and other 163 176 Total property, plant and equipment 4,577 5,552 Less: accumulated depreciation 1,880 2,042 Property, plant and equipment, net $ 2,697 $ 3,510 Capital expenditures related to assets subject to sales-type lease arrangements were $72 million for the year ended December 31, 2022; these amounts are reflected as Additions to property, plant and equipment in the Consolidated Statements of Cash Flows.
Lessor, Sales-type Leases	Lessor Based on the terms of fee-based transportation and storage services agreements with MPC and third parties, MPLX is considered to be the lessor under several operating lease arrangements in accordance with GAAP. These agreements have remaining terms ranging from less than one year to 10 years with renewal options ranging from one year to five years, and some agreements having multiple renewal options. We are also considered to be the lessor under several operating lease agreements related to certain fee-based natural gas transportation and processing agreements in the Marcellus and Southern Appalachia region. The primary term of these agreements expire between 2026 and 2036, however, these contracts either have renewal options or will continue thereafter on a year-to-year basis until terminated by either party. Lease revenues included on the Consolidated Statements of Income during 2022, 2021 and 2020 were as follows: 2022 2021 2020 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 763 $ 327 $ 743 $ 376 $ 952 $ 398 Sales-type leases: Interest income (Sales-type rental revenue- fixed minimum) 447 46 431 — 151 — Interest income (Revenue from variable lease payments) 18 16 4 — 1 — Sales-type lease revenue $ 465 $ 62 $ 435 $ — $ 152 $ — MPLX did not elect to use the practical expedient to combine lease and non-lease components for lessor arrangements. The tables below represent the portion of the contract allocated to the lease component based on relative standalone selling price. We elected the practical expedient to carry forward historical classification conclusions until a modification of an existing agreement occurs. Once a modification occurs, the amended agreement is required to be assessed under ASC 842, to determine whether a reclassification of the lease is required. 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. Additionally, during the twelve months ended December 31, 2022, 2021 and 2020, we executed amendments to certain related party storage, transportation and terminal service agreements between MPLX and MPC to provide for reimbursements for projects, changes to minimum volume commitments or to extend the term of the agreement. The changes required the embedded leases within these agreements to be reassessed under ASC 842. As a result of these lease assessments, certain leases were reclassified from an operating lease to a sales-type lease. Accordingly, the underlying property, plant and equipment, net, and associated deferred revenue, if any, were derecognized and 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 respective periods. 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. 2022 2021 2020 (In millions) Related Party (1) Third Party (2) Related Party (1) Third Party Related Party (1) Third Party Lease receivables $ 87 $ 914 $ 519 $ — $ 370 $ — Unguaranteed residual assets 6 63 14 — 10 — Property, plant and equipment, net (50) (745) (421) — (171) — Deferred revenue — 277 — — — — Amount recognized on commencement date $ 43 $ 509 $ 112 $ — $ 209 $ — (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. The following is a schedule of minimum future rental revenue on the non-cancellable operating leases as of December 31, 2022: (In millions) Related Party Third Party Total 2023 $ 627 $ 97 $ 724 2024 569 95 664 2025 546 64 610 2026 446 37 483 2027 330 16 346 2028 and thereafter 149 21 170 Total minimum future rentals $ 2,667 $ 330 $ 2,997 Annual minimum undiscounted lease payment receipts under our sales-type leases were as follows as of December 31, 2022: (In millions) Related Party Third Party Total 2023 $ 489 $ 169 $ 658 2024 489 156 645 2025 489 146 635 2026 459 137 596 2027 357 128 485 2028 and thereafter 214 970 1,184 Total minimum future rentals 2,497 1,706 4,203 Less: present value discount 1,503 765 2,268 Lease receivable (1) $ 994 941 1,935 Current lease receivables (2) 111 98 209 Long-term lease receivables (3) 883 843 1,726 Unguaranteed residual assets (3) 87 66 153 Total sales-type lease assets $ 1,081 $ 1,007 $ 2,088 (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. The following schedule summarizes MPLX’s investment in assets held under operating lease by major classes as of December 31, 2022 and 2021: December 31, (In millions) 2022 2021 Pipelines $ 670 $ 953 Refining logistics 1,310 1,146 Terminals 1,241 1,290 Marine 126 129 Gathering and transportation 94 991 Processing and fractionation 973 867 Land, building and other 163 176 Total property, plant and equipment 4,577 5,552 Less: accumulated depreciation 1,880 2,042 Property, plant and equipment, net $ 2,697 $ 3,510 Capital expenditures related to assets subject to sales-type lease arrangements were $72 million for the year ended December 31, 2022; these amounts are reflected as Additions to property, plant and equipment in the Consolidated Statements of Cash Flows.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	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 December 31, 2022 and 2021, accrued liabilities for remediation totaled $ 17 million 23 million 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. After subsequent appeal proceedings and in compliance with a new order issued by the BIA, in December 2020, THPP paid approximately $4 million in assessed trespass damages and ceased use of the portion of the pipeline that crosses the property at issue. In March 2021, the BIA issued an order purporting to vacate the BIA's prior orders related to THPP’s alleged trespass and direct the Regional Director of the BIA to reconsider the issue of THPP’s alleged trespass and issue a new order. In April 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 2021 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 and counterclaims to THPP’s suit claiming 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. 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 Over the years, MPLX has sold various assets in the normal course of its business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require MPLX to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. MPLX is typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based. We hold a 9.19 percent indirect interest in 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. The EIS has been delayed and the Army Corps currently expects to release a draft EIS in 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 December 31, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million. Contractual Commitments and Contingencies At December 31, 2022, MPLX’s contractual commitments to acquire property, plant and equipment totaled $165 million. These commitments were primarily related to G&P plant expansions. In addition, from time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of December 31, 2022, management does not believe there are any indications that MPLX will not be able to meet the construction milestones, that force majeure does not apply or that such fees and charges will otherwise be triggered. Other Contractual Obligations MPLX executed various third-party transportation and terminalling agreements that obligate us to minimum volume, throughput or payment commitments over the remaining terms of the agreements, which range from less than one year to nine years. After the minimum volume commitments are met in the transportation and terminalling agreements, MPLX pays additional amounts based on throughput. There are escalation clauses in the transportation and terminalling agreements, which are based on Consumer Price Index adjustments. The minimum future payments under these agreements as of December 31, 2022 are as follows: (In millions) 2023 $ 162 2024 152 2025 128 2026 118 2027 114 2028 and thereafter 204 Total $ 878

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On February 9, 2023, MPLX issued $1.6 billion aggregate principal amount of notes, consisting of $1.1 billion principal amount of 5.00 percent senior notes due 2033 and $500 million principal amount of 5.650 percent senior notes due 2053. The 2033 Senior Notes and 2053 Senior Notes will mature on March 1, 2033 and March 1, 2053, respectively. The 2033 Senior Notes were offered at a price to the public of 99.170 percent with interest payable semi-annually in arrears, commencing on September 1, 2023. The 2053 Senior Notes were offered at a price to the public of 99.536 percent with interest payable semi-annually in arrears, commencing on September 1, 2023. On February 15, 2023, MPLX used $600 million of the net proceeds from the 2033 Senior Notes and the 2053 Senior Notes to redeem all of the outstanding Series B preferred units. We also provided notice to redeem all of MPLX’s and MarkWest’s $1.0 billion aggregate principal amount of 4.50 percent senior notes due July 2023.

Description of Business and B_2

Description of Business and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2022
Limited Liability Company or Limited Partnership, Business Organization and Operations [Abstract]
Basis of presentation	Basis of Presentation The accompanying consolidated financial statements of MPLX have been prepared in accordance with GAAP. The 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.

Summary of Principal Accounti_2

Summary of Principal Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Use of estimates	Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the respective reporting periods. Actual results could differ materially from those estimates. Estimates are subject to uncertainties due to the levels of subjectivity and judgment necessary to account for highly uncertain matters or the susceptibility of such matters to change and affect items such as valuing identified intangible assets; determining the fair value of derivative instruments; evaluating impairments of long-lived assets, goodwill and equity investments; establishing estimated useful lives for long-lived assets; acquisition accounting; estimating revenues, expense accruals and capital expenditures; valuing AROs; recognizing share-based compensation expense; and determining liabilities, if any, for environmental and legal contingencies.
Revenue recognition	Revenue Recognition Revenue is measured based on consideration specified in a contract with a customer. MPLX recognizes revenue when it satisfies a performance obligation by transferring control over a product or providing services to a customer. MPLX enters into a variety of contract types in order to generate Product sales and Service revenue. MPLX provides services under the following types of arrangements: • Fee-based arrangements – Under fee-based arrangements, MPLX receives fees for the following services: gathering, processing and transportation of natural gas; transportation, fractionation, exchange and storage of NGLs; and transportation, terminalling, storage and distribution of crude oil, refined products, other hydrocarbon-based products, and renewables. The revenue MPLX earns from these arrangements is generally directly related to the volume of natural gas, NGLs, refined products or crude oil that is handled by or flows through MPLX’s systems and facilities and is not normally directly dependent on commodity prices. In certain cases, MPLX’s arrangements provide for minimum volume commitments. Fee-based arrangements are reported as Service revenue on the Consolidated Statements of Income. Revenue is recognized over time as services are performed. In certain instances when specifically stated in the contract terms, MPLX purchases product after fee-based services have been provided. Revenue from the sale of products purchased after services are provided is reported as Product sales on the Consolidated Statements of Income and recognized on a gross basis, as MPLX takes control of the product and is the principal in the transaction. • Percent-of-proceeds arrangements – Under percent-of-proceeds arrangements, MPLX gathers and processes natural gas on behalf of producers; sells the resulting residue gas, condensate and NGLs at market prices; and remits to producers an agreed-upon percentage of the proceeds. In other cases, instead of remitting cash payments to the producer, MPLX delivers an agreed-upon percentage of the residue gas and NGLs to the producer (take-in-kind arrangements) and sells the volumes MPLX retains to third parties or related parties. Revenue is recognized on a net basis when MPLX acts as an agent and does not have control of the gross amount of gas and/or NGLs prior to it being sold. Percent-of-proceeds revenue is reported as Service revenue - product related on the Consolidated Statements of Income. • Keep-whole arrangements – Under keep-whole arrangements, MPLX gathers natural gas from the producer, processes the natural gas and sells the resulting condensate and NGLs to third parties at market prices. Because the extraction of the condensate and NGLs from the natural gas during processing reduces the Btu content of the natural gas, MPLX must either purchase natural gas at market prices for return to producers or make cash payment to the producers equal to the value of the energy content of this natural gas. Certain keep-whole arrangements also have provisions that require MPLX to share a percentage of the keep-whole profits with the producers based on the oil to gas ratio or the NGL to gas ratio. Service revenue - product related is recorded based on the value of the NGLs received on the date the services are performed. Natural gas purchased to return to the producer and shared NGL profits are recorded as a reduction of Service revenue - product related on the Consolidated Statements of Income on the date the services are performed. Sales of NGLs under these arrangements are reported as Product sales on the Consolidated Statements of Income and are reported on a gross basis as MPLX is the principal in the arrangement and controls the product prior to sale. The sale of the NGLs may occur shortly after services are performed at the tailgate of the plant, or after a period of time as determined by MPLX. • Purchase arrangements – Under purchase arrangements, MPLX purchases natural gas at either the wellhead or the tailgate of a plant. MPLX then gathers and delivers the natural gas to pipelines where MPLX may resell the natural gas. Wellhead purchase arrangements represent an arrangement with a supplier and are recorded in Purchased product costs. Often, MPLX earns fees for services performed prior to taking control of the product in these arrangements and Service revenue is recorded for these fees. Revenue generated from the sale of product obtained in tailgate purchase arrangements is reported as Product sales on the Consolidated Statements of Income and is recognized on a gross basis as MPLX purchases and takes control of the product prior to sale and is the principal in the transaction. In many cases, MPLX provides services under contracts that contain a combination of more than one of the arrangements described above. When fees are charged (in addition to product received) under percent-of-proceeds arrangements, keep-whole arrangements or purchase arrangements, MPLX records such fees as Service revenue on the Consolidated Statements of Income. The terms of MPLX’s contracts vary based on gas quality conditions, the competitive environment when the contracts are signed, and customer requirements. Performance obligations are determined based on the specific terms of the arrangements, economics of the geographical regions, and the services offered and whether they are deemed distinct. MPLX allocates the consideration earned between the performance obligations based on the stand-alone selling price when multiple performance obligations are identified. Revenue from MPLX’s service arrangements will generally be recognized over time as the performance obligation is satisfied as services are provided. MPLX has elected to use the output measure of progress to recognize revenue based on the units delivered, processed or transported. The transaction price may have fixed components related to minimum volume commitments and variable components, which are primarily dependent on volumes. Variable consideration will generally not be estimated at contract inception as the transaction price is specifically allocable to the services provided each period. In instances in which tiered pricing structures do not reflect our efforts to perform, MPLX will estimate variable consideration at contract inception. Product sales will be recognized at a point in time when control of the product transfers to the customer. Minimum volume commitments may create contract liabilities if current period payments can be used for future services. Breakage is estimated and recognized into service revenue in instances where it is probable the customer will not use the credit in future periods. Amounts billed to customers for shipping and handling, electricity, and other costs to perform services are included in the transaction price as a component of Revenues and other income on the Consolidated Statements of Income. Shipping and handling costs associated with product sales are included in Purchased product costs on the Consolidated Statements of Income. Customers usually pay monthly based on the products purchased or services performed that month. Taxes collected from customers and remitted to the appropriate taxing authority are excluded from revenue.
Revenue and expense accruals	Revenue and Expense Accruals MPLX routinely makes accruals based on estimates for both revenues and expenses due to the timing of compiling billing information, receiving certain third-party information and reconciling MPLX’s records with those of third parties. The delayed information from third parties includes, among other things, actual volumes purchased, transported or sold, adjustments to inventory and invoices for purchases, actual natural gas and NGL deliveries, and other operating expenses. MPLX makes accruals to reflect estimates for these items based on its internal records and information from third parties. Estimated accruals are adjusted when actual information is received from third parties and MPLX’s internal records have been reconciled.
Other taxes	Other Taxes Other taxes primarily include real estate taxes.
Cash and Cash Equivalents, Policy	Cash and Cash Equivalents Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid debt instruments with maturities of three months or less.
Receivables	Receivables Receivables primarily consist of customer accounts receivable, which are recorded at the invoiced amount and generally do not bear interest. Allowances for doubtful accounts are generally recorded when it becomes probable that the receivable will not be collected and are recorded to bad debt expense. We review the allowance quarterly with past-due balances over 150 days and other higher-risk amounts being reviewed individually for collectability. Balances that remain outstanding after reasonable collection efforts have been unsuccessful are written off through a charge to the valuation allowance and a credit to accounts receivable.
Lessee, Leases	Leases Contracts with a term greater than one year that convey the right to direct the use of and obtain substantially all of the economic benefit of an asset are accounted for as right of use (“ROU”) assets and lease liabilities. Right of use asset and lease liability balances are recorded at the commencement date at present value of the fixed lease payments using a secured incremental borrowing rate with a maturity similar to the lease term because our leases do not provide implicit rates. We have elected to include both lease and non-lease components in the present value of the lease payments for all lessee asset classes with the exception of our marine and third-party contractor service and equipment leases. The lease component of the payment for the marine and equipment asset classes is determined using a relative standalone selling price. Operating lease expense is recognized on a straight-line basis over the lease term. See Note 20 for additional disclosures about our lease contracts.
Lessor, Leases	As a lessor under ASC 842, MPLX may be required to re-classify existing operating leases to sales-type leases upon modification and related reassessment of the leases. See Note 20 for further information regarding our ongoing evaluation of the impacts of lease reassessments as modifications occur. The net investment in sales-type leases with third parties is recorded within Receivables, net and Other noncurrent assets on the Consolidated Balance Sheets. The net investment in sales-type leases with related parties is recorded within Current assets - related parties and Noncurrent assets - related parties on the Consolidated Balance Sheets. These amounts are comprised of the present value of the sum of the future minimum lease payments representing the value of the lease receivable and the unguaranteed residual value of the leased assets. Management assesses the net investment in sales-type leases for recoverability quarterly.
Inventories	Inventories Inventories consist of materials and supplies to be used in operations, line fill and other NGLs. Cost for materials and supplies are determined primarily using the weighted-average cost method. Inventories are valued at the lower of cost or net realizable value.
Imbalances	Imbalances Within our pipelines and storage assets, we experience volume gains and losses due to pressure and temperature changes, evaporation and variances in meter readings and other measurement methods. Until settled, positive imbalances are recorded as other current assets and negative imbalances are recorded as accounts payable. Positive and negative imbalances are settled in cash, settled by physical delivery of volumes from a different source, or tracked and settled in the future.
Investment in unconsolidated affiliates	Investment in Unconsolidated Affiliates Equity investments in which MPLX exercises significant influence but does not control and is not the primary beneficiary, are accounted for using the equity method and are reported in Equity method investments on the accompanying Consolidated Balance Sheets. This includes entities in which we hold majority ownership, but the minority shareholders have substantive participating rights. Differences in the basis of the investments and the separate net asset values of the investees, if any, are amortized into net income over the remaining useful lives of the underlying assets and liabilities, except for the excess related to goodwill. Regular evaluation of these investments is appropriate to evaluate any potential need for impairment. MPLX uses evidence of a loss in value to identify if an investment has an other than a temporary decline. Impairments are recorded through Income from equity method investments.
Property, plant and equipment	Property, Plant and Equipment Property, plant and equipment are recorded at cost and depreciated on a straight-line basis over the estimated useful lives of the assets. Expenditures that extend the useful lives of assets are capitalized. 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 flows 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 future cash flows from the use of the asset group and its eventual disposition is less than the carrying value of an asset group, an impairment assessment is performed and the excess of the book value over the fair value is recorded as an impairment loss. When items of property, plant and equipment are sold or otherwise disposed of, any gains or losses are reported on the Consolidated Statements of Income. Gains on the disposal of property, plant and equipment are recognized when they occur, which is generally at the time of closing. If a loss on disposal is expected, such losses are recognized when the assets are classified as held for sale.
Goodwill and Intangible Assets, Policy	Goodwill and Intangibles Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in the acquisition of a business. Goodwill is not amortized, but rather is tested for impairment at the reporting unit level annually and when events or changes in circumstances indicate that the fair value of a reporting unit with goodwill has been reduced below carrying value. If we determine, based on a qualitative assessment, that it is not more likely than not that a reporting unit’s fair value is less than its carrying amount, no further impairment testing is required. If we do not perform a qualitative assessment or if that assessment indicates that further impairment testing is required, the fair value of each reporting unit is determined using an income and market approach which is compared to the carrying value of the reporting unit. If the carrying amount of the reporting unit exceeds its fair value, an impairment loss would be recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to that reporting unit. The fair value under the income approach is calculated using the expected present value of future cash flows method. Significant assumptions used in the cash flow forecasts include future net operating margins, future volumes, discount rates, and future capital requirements. See Note 14 for further details. Amortization of intangibles with definite lives is calculated using the straight-line method, which is reflective of the benefit pattern in which the estimated economic benefit is expected to be received over the estimated useful life of the intangible asset. Intangibles subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the intangible may not be recoverable. If the sum of the expected undiscounted future cash flows related to the asset is less than the carrying amount of the asset, an impairment loss is recognized based on the fair value of the asset.
Environmental costs	Environmental Costs Environmental expenditures for additional equipment that mitigates or prevents future contamination or improves environmental safety or efficiency of the existing assets are capitalized. We recognize remediation costs and penalties when the responsibility
Asset retirement obligations	Asset Retirement ObligationsAn ARO is a legal obligation associated with the retirement of tangible long-lived assets that generally result from the acquisition, construction, development or normal operation of the asset. The fair value of AROs is recognized in the period in which the obligations are incurred, if a reasonable estimate of fair value can be made, and added to the carrying amount of the associated asset. This additional carrying amount is then depreciated over the life of the asset. The liability is determined using a credit adjusted risk free interest rate and increases due to the passage of time based on the time value of money until the obligation is settled. AROs have not been recognized for certain assets because the fair value cannot be reasonably estimated since the settlement dates of the obligations are indeterminate. Such obligations will be recognized in the period when sufficient information becomes available to estimate a range of potential settlement dates. As of December 31, 2022 and 2021, MPLX’s asset retirement obligation was $34 million and $31 million, respectively, and is included on the balance sheet within Other long-term liabilities.
Derivative instruments	Derivative Instruments MPLX may use commodity derivatives to economically hedge a portion of its exposure to commodity price risk. All derivative instruments (including derivatives embedded in other contracts) are recorded at fair value. MPLX discloses the fair value of all derivative instruments under the captions Other current assets, Other noncurrent assets, Other current liabilities and Other long-term liabilities on the Consolidated Balance Sheets. 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. Changes in the fair value of derivative instruments are reported on the Consolidated Statements of Income in accounts related to the item whose value or cash flows are being managed. Derivative instruments are marked to market through Purchased product costs on the Consolidated Statements of Income. Certain commodity derivative positions are governed by master netting arrangements and are reflected on the consolidated balance sheets on a net basis by counterparty. MPLX did not utilize any commodity derivatives during the years ended December 31, 2022, 2021 and 2020, and therefore did not elect hedge accounting. MPLX has historically elected the normal purchases and normal sales designation for certain contracts related to the physical purchase of electric power and the sale of some commodities.
Fair value measurement	Fair Value Measurement Financial assets and liabilities recorded at fair value in the Consolidated Balance Sheets are categorized based upon the fair value hierarchy established by GAAP, which classifies the inputs used to measure fair value into Level 1, Level 2 or Level 3. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The methods and assumptions utilized may produce a fair value that may not be realized in future periods upon settlement. Furthermore, while MPLX believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. For further discussion, see Note 15.
Equity-based compensation arrangements	Equity-Based Compensation Arrangements MPLX issues phantom units under the MPLX LP 2018 Incentive Compensation Plan. A phantom unit entitles the grantee a right to receive a common unit upon the issuance of the phantom unit. The fair value of phantom unit awards granted to employees and non-employee directors is based on the fair market value of MPLX LP common units on the date of grant. The fair value of the units awarded is amortized into earnings using a straight-line amortization schedule over the period of service corresponding with the vesting period. For phantom units that vest immediately and are not forfeitable, equity-based compensation expense is recognized at the time of grant. MPLX previously issued performance units under the MPLX LP 2018 Incentive Compensation Plan. Performance units paying out in cash are accounted for as liability awards and recorded at fair value with a mark-to-market adjustment made each quarter. The performance units paying out in units are accounted for as equity awards. Equity-classified performance units with a market condition use a Monte Carlo valuation model to calculate a grant date fair value of market conditions. Equity-classified performance units with a performance condition are valued based on the grant date fair value of the payout deemed most probable to occur and is adjusted as the expectation for payout changes. All the outstanding performance unit awards have been settled as of February 1, 2023.
Income Tax, Policy	Income Taxes MPLX is not a taxable entity for United States federal income tax purposes or for the majority of the states that impose an income tax. Taxes on MPLX’s net income generally are borne by its partners through the allocation of taxable income. MPLX’s taxable income or loss, which may vary substantially from the net income or loss reported on the Consolidated Statements of Income, is includable in the federal income tax returns of each partner. MPLX and certain legal entities are, however, taxable entities under certain state jurisdictions. MPLX accounts for income taxes under the asset and liability method. Deferred income taxes are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis, capital loss carryforwards and net operating loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of any tax rate change on deferred taxes is recognized as tax expense/(benefit) from continuing operations in the period that includes the enactment date of the tax rate change. Realizability of deferred tax assets is assessed and, if not more likely than not, a valuation allowance is recorded to reflect the deferred tax assets at net realizable value as determined by management. All deferred tax balances are classified as long-term in the accompanying Consolidated Balance Sheets. All changes in the tax bases of assets and liabilities are allocated among operations and items charged or credited directly to equity.
Distribution Policy, Limited Partners	Distributions In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule, as discussed in Notes 7 and 9, and subsequently allocated to the limited partner unitholders. Distributions, although earned, are not accrued as a liability until declared. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described below.
Net income per limited partner unit	Net Income Per Limited Partner Unit MPLX uses the two-class method when calculating the net income per unit applicable to limited partners, because there is more than one class of participating security. The classes of participating securities include common units, Series A and Series B preferred units and certain equity-based compensation awards. Net income attributable to MPLX LP is allocated to the unitholders differently for preparation of the Consolidated Statements of Equity and the calculation of net income per limited partner unit. In preparing the Consolidated Statements of Equity, net income attributable to MPLX LP is allocated to Series A and Series B preferred unitholders based on a fixed distribution schedule and subsequently allocated to remaining unitholders in accordance with their respective ownership percentages. The allocation of net income attributable to MPLX LP for purposes of calculating net income per limited partner unit is described in Note 8. In preparing net income per limited partner units, during periods in which a net loss attributable to MPLX is reported or periods in which the total distributions exceed the reported net income attributable to MPLX’s unitholders, the amount allocable to certain equity-based compensation awards is based on actual distributions to the equity-based compensation awards. Diluted earnings per unit is calculated by dividing net income attributable to MPLX’s common unitholders, after deducting amounts allocable to other participating securities, by the weighted average number of common units and potential common units outstanding during the period. Potential common units are excluded from the calculation of diluted earnings per unit during periods in which net income attributable to MPLX’s unitholders, after deducting amounts that are allocable to the outstanding equity-based compensation awards and preferred units, is a loss, as the impact would be anti-dilutive.
Business combinations	Business Combinations We recognize and measure the assets acquired and liabilities assumed in a business combination based on their estimated fair values at the acquisition date. Any excess or deficit of the purchase consideration when compared to the fair value of the net tangible assets acquired, if any, is recorded as goodwill or gain from a bargain purchase. Depending on the nature of the transaction, management may engage an independent valuation specialist to assist with the determination of fair value of the assets acquired, liabilities assumed, noncontrolling interests, if any, and goodwill, based on recognized business valuation methodologies. An income, market or cost valuation method may be utilized to estimate the fair value of the assets acquired, liabilities assumed, and noncontrolling interests, if any, in a business combination. The income valuation method represents the present value of future cash flows over the life of the asset using: (i) discrete financial forecasts, which rely on management’s estimates of volumes, certain commodity prices, revenue and operating expenses; (ii) long-term growth rates; and (iii) appropriate discount rates. The market valuation method uses prices paid for a reasonably similar asset by other purchasers in the market, with adjustments relating to any differences between the assets. The cost valuation method is based on the replacement cost of a comparable asset at prices at the time of the acquisition reduced for depreciation of the asset. If the initial accounting for the business combination is incomplete by the end of the reporting period in which the acquisition occurs, an estimate will be recorded. Subsequent to the acquisition, and not later than one year from the acquisition date, MPLX will record any material adjustments to the initial estimate based on new information obtained that would have existed as of the acquisition date. An adjustment that arises from information obtained that did not exist as of the date of the acquisition will be recorded in the period of the adjustment. Acquisition-related costs are expensed as incurred in connection with each business combination. Acquisitions in which the company or business being acquired by MPLX had an existing relationship with MPC may result in the transaction being considered a transfer between entities under common control. In these situations, MPLX records the assets acquired and liabilities assumed on its consolidated balance sheets at MPC’s historical carrying value. For the acquiring entity, transfers of businesses between entities under common control require prior periods to be retrospectively adjusted for those dates that the entity was under common control.

Investments and Noncontrollin_2

Investments and Noncontrolling Interests (Tables)	12 Months Ended
	Dec. 31, 2022
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	The following table presents MPLX’s equity method investments at the dates indicated: Ownership as of Carrying value at December 31, December 31, (In millions, except ownership percentages) VIE 2022 2022 2021 L&S Andeavor Logistics Rio Pipeline LLC X 67% $ 177 $ 183 Illinois Extension Pipeline Company, L.L.C. 35% 236 243 LOOP LLC 41% 287 265 MarEn Bakken Company LLC (1) 25% 475 449 Minnesota Pipe Line Company, LLC 17% 178 183 Whistler Pipeline LLC X 38% 211 155 Other (2) X 269 240 Total L&S 1,833 1,718 G&P Centrahoma Processing LLC 40% 131 133 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. X 67% 335 332 MarkWest Torñado GP, L.L.C. X 60% 306 246 MarkWest Utica EMG, L.L.C. X 57% 669 680 Rendezvous Gas Services, L.L.C. X 78% 137 147 Sherwood Midstream Holdings LLC X 51% 125 136 Sherwood Midstream LLC X 50% 512 544 Other (2) X 47 45 Total G&P 2,262 2,263 Total $ 4,095 $ 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) Some investments included within Other have also been deemed to be VIEs.
Investment Company, Nonconsolidated Subsidiary, Summarized Financial Information	Summarized financial information for MPLX’s equity method investments for the years ended December 31, 2022, 2021 and 2020 is as follows: December 31, 2022 (In millions) Other VIEs Non-VIEs Total Revenues and other income $ 1,197 $ 1,456 $ 2,653 Costs and expenses 603 648 1,251 Income from operations 594 808 1,402 Net income 535 711 1,246 Income from equity method investments $ 275 $ 201 $ 476 December 31, 2021 (In millions) Other VIEs Non-VIEs Total Revenues and other income $ 820 $ 1,236 $ 2,056 Costs and expenses 490 568 1,058 Income from operations 330 668 998 Net income 266 594 860 Income from equity method investments (1) $ 175 $ 146 $ 321 December 31, 2020 (In millions) Other VIEs Non-VIEs Total Revenues and other income $ 298 $ 1,208 $ 1,506 Costs and expenses 414 531 945 (Loss)/income from operations (116) 677 561 Net (loss)/income (175) 615 440 (Loss)/income from equity method investments (1) $ (1,100) $ 164 $ (936) (1) The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively. Summarized balance sheet information for MPLX’s equity method investments as of December 31, 2022 and 2021 is as follows: December 31, 2022 (In millions) Other VIEs Non-VIEs Total Current assets $ 474 $ 450 $ 924 Noncurrent assets 7,721 5,225 12,946 Current liabilities 323 181 504 Noncurrent liabilities $ 2,546 $ 876 $ 3,422 December 31, 2021 (In millions) Other VIEs Non-VIEs Total Current assets $ 335 $ 411 $ 746 Noncurrent assets 7,439 4,895 12,334 Current liabilities 217 310 527 Noncurrent liabilities $ 2,461 $ 788 $ 3,249

Related Party Agreements and _2

Related Party Agreements and Transactions (Tables)	12 Months Ended
	Dec. 31, 2022
Related Party Transaction [Line Items]
Related Party Transactions Disclosure [Text Block]	Related Party Agreements and Transactions MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below. MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products and other fees for storage capacity; operating and management fees; as well as reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under the marine transportation service agreement. In addition, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services type agreements as well as various other agreements as discussed below. The commercial agreements with MPC include: • MPLX has a fuels distribution agreement with MPC under which MPC pays MPLX a tiered monthly volume-based fee for marketing and selling MPC’s products. This agreement is subject to a minimum quarterly volume and has an initial term of 10 years, subject to a five • MPLX has various pipeline transportation agreements under which MPC pays MPLX fees for transporting crude and refined products on MPLX’s pipeline systems. These agreements are subject to minimum throughput volumes under which MPC will pay MPLX deficiency payments for any period in which they do not ship the minimum committed volume. Under certain agreements, deficiency payments can be applied as credits to future periods in which MPC ships volumes in excess of the minimum volume, subject to a limited period of time. These agreements are subject to various terms and renewal periods. • MPLX has a marine transportation agreement with an initial term of six years under which MPC pays MPLX fees for providing marine transportation of crude oil, feedstock and refined petroleum products, and related services. This agreement is subject to two automatic renewal periods of five years each. This agreement is currently in the first renewal term. • MPLX has a month-to-month trucking transportation services agreement under which MPC pays MPLX fees for gathering barrels and providing trucking, dispatch, delivery and data services. • MPLX has numerous storage services agreements governing storage services at various types of facilities including terminals, pipeline tank farms, caverns and refineries, under which MPC pays MPLX per-barrel fees for providing storage services. Some of these agreements provide MPC with exclusive access to storage at certain locations, such as storage located at MPC’s refineries or storage in certain caverns. Under these agreements, MPC pays MPLX a per-barrel fee for such storage capacity, regardless of whether MPC fully utilizes the available capacity. These agreements are subject to various terms and renewal periods. • MPLX has multiple terminal services agreements governing certain terminals under which MPC pays MPLX fees for terminal services. Under these agreements MPC pays MPLX agreed upon fees relating to MPC product receipts, deliveries and storage as well as any blending, additization, handling, transfers or other related charges. Many of these agreements are subject to minimum volume throughput commitments, or to various minimum commitments related to some or all terminal activities, under which MPC pays a deficiency payment for any period in which they do not meet the minimum commitment. Some of these agreements allow for deficiency payments to be applied as credits to a limited number of future periods with excess throughput volumes. These agreements are subject to various terms and renewal periods. • MPLX 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. The pricing structure under this agreement provides for a base volume subject to a base rate and incremental volumes subject to variable rates, which are calculated with reference to certain of our costs incurred as processor of the volumes. The pricing for both the base and incremental volumes are subject to revision each year. This agreement is subject to automatic three-month renewal periods. In many cases, agreements are location-based hybrid agreements, containing provisions relating to multiple of the types of agreements and services described above. Operating Agreements MPLX operates various pipelines owned by MPC under operating services agreements. Under these operating services agreements, MPLX receives an operating fee for operating the assets and is reimbursed for all direct and indirect costs associated with operating the assets. Most of these agreements are indexed for inflation. These agreements range from one Co-location Services Agreements MPLX is party to co-location services agreements with MPC’s refineries, under which MPC provides management, operational and other services to MPLX. MPLX pays MPC monthly fixed fees and direct reimbursements for such services calculated as set forth in the agreements. These agreements have initial terms of 50 years. Ground Lease Agreements MPLX is party to ground lease agreements with certain of MPC’s refineries under which MPLX is the lessee of certain sections of property which contain facilities owned by MPLX and are within the premises of MPC’s refineries. MPLX pays MPC monthly fixed fees under these ground leases. These agreements are subject to various terms. Marine Services Agreements with MPC MPLX has a management services agreement with MPC under which it provides management services to assist MPC in the oversight and management of the marine business. MPLX receives fixed annual fees for providing the required services, which are subject to predetermined annual escalation rates. This agreement is subject to an initial term of five years and automatically renews for one additional five Omnibus Agreements MPLX has omnibus agreements with MPC that address MPLX’s payment of fixed annual fees to MPC for the provision of executive management services by certain executive officers of the general partner and MPLX’s reimbursement of MPC for the provision of certain general and administrative services to it. They also provide for MPC’s indemnification to MPLX for certain matters, including environmental, title and tax matters; as well as our indemnification of MPC for certain matters under these agreements. Employee Services Agreements MPLX has various employee services agreements and secondment agreements with MPC under which MPLX reimburses MPC for employee benefit expenses, along with the provision of operational and management services in support of both our L&S and G&P segments’ operations. Related Party Loan MPLX is party to a loan agreement (the “MPC Loan Agreement”) with MPC. Under the terms of the MPC Loan Agreement, MPC extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC. 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 MPC Loan Agreement are scheduled to mature and become due and payable on July 31, 2024, provided that MPC 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 bore 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 17. The MPC Loan Agreement was amended effective January 1, 2023 to update the interest rate to one-month term SOFR adjusted upward by 0.10 percent plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 17. All other terms of the MPC Loan Agreement remain unchanged. Activity on the MPC Loan Agreement was as follows: (In millions, except %) December 31, 2022 December 31, 2021 Borrowings $ 2,989 $ 8,493 Weighted average interest rate of borrowings 1.50 % 1.34 % Repayments $ 4,439 $ 7,043 Outstanding balance at end of period $ — $ 1,450 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. Amounts earned under 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 years ended December 31, 2022, 2021 and 2020, these sales totaled $1,002 million, $811 million and $462 million, respectively. Related Party Expenses MPC charges MPLX for executive management services and certain general and administrative services provided to MPLX under the terms of our omnibus agreements (“Omnibus charges”) and for certain employee services provided to MPLX under employee services agreements (“ESA charges”). Omnibus charges and ESA charges are classified as Rental cost of sales - related parties, Purchases - related parties, or General and administrative expenses depending on the nature of the asset or activity with which the costs are associated. In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain rent and lease agreements with MPC. Starting in 2020, MPC advanced certain strategic priorities to lay a foundation for long-term success, including plans to optimize its assets and structurally lower costs in 2021 and beyond, which included an involuntary workforce reduction plan. The workforce reduction plan, together with employee reductions resulting from MPC's indefinite idling of its Martinez, California and Gallup, New Mexico refineries, affected approximately 2,050 employees. All of the employees that conduct MPLX’s business are directly employed by affiliates of MPC, and certain of those employees were affected by MPC’s workforce reductions. During 2020, MPLX reimbursed MPC for $37 million related to severance and employee benefits related expenses that MPC recorded in connection with its workforce reductions. These costs are shown on the Consolidated Statements of Income as Restructuring expenses. There were no similar costs in 2021 or 2022. For the years ended December 31, 2022, 2021 and 2020, General and administrative expenses incurred from MPC totaled $235 million, $250 million and $254 million, respectively. Some charges incurred under the omnibus and employee service agreements are related to engineering services and are associated with assets under construction. These charges are added to Property, plant and equipment, net on the Consolidated Balance Sheets. For 2022, 2021 and 2020, these charges totaled $70 million, $55 million and $97 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 (see Note 20 for additional information) and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts 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. December 31, (In millions) 2022 2021 Current assets - related parties Receivables $ 610 $ 555 Lease receivables 111 82 Prepaid 5 4 Other 3 3 Total 729 644 Noncurrent assets - related parties Long-term lease receivables 883 854 Right of use assets 228 229 Unguaranteed residual asset 87 47 Long-term receivables 27 31 Total 1,225 1,161 Current liabilities - related parties MPC loan agreement and other payables (1) 262 1,702 Deferred revenue 80 77 Operating lease liabilities 1 1 Total 343 1,780 Long-term liabilities - related parties Long-term operating lease liabilities 228 228 Long-term deferred revenue 110 74 Total $ 338 $ 302 (1) Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the MPC Loan Agreement. There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2022. Other Related Party Transactions From time to time, MPLX may also sell to or purchase from related parties, assets and inventory at the lesser of average unit cost or net realizable value. Sales to related parties for the years ended December 31, 2022, 2021 and 2020 were $25 million, $26 million and $10 million, respectively. Purchases from related parties for the year ended December 31, 2022 were $31 million and were immaterial for the years ended December 31, 2021 and 2020.
Schedule of Related Party Transactions [Table Text Block]	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 (see Note 20 for additional information) and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts 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. December 31, (In millions) 2022 2021 Current assets - related parties Receivables $ 610 $ 555 Lease receivables 111 82 Prepaid 5 4 Other 3 3 Total 729 644 Noncurrent assets - related parties Long-term lease receivables 883 854 Right of use assets 228 229 Unguaranteed residual asset 87 47 Long-term receivables 27 31 Total 1,225 1,161 Current liabilities - related parties MPC loan agreement and other payables (1) 262 1,702 Deferred revenue 80 77 Operating lease liabilities 1 1 Total 343 1,780 Long-term liabilities - related parties Long-term operating lease liabilities 228 228 Long-term deferred revenue 110 74 Total $ 338 $ 302 (1) Includes $1,450 million as of December 31, 2021 related to outstanding borrowings on the MPC Loan Agreement. There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2022.
Schedule of Short-Term Debt [Table Text Block]	Related Party Loan MPLX is party to a loan agreement (the “MPC Loan Agreement”) with MPC. Under the terms of the MPC Loan Agreement, MPC extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC. 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 MPC Loan Agreement are scheduled to mature and become due and payable on July 31, 2024, provided that MPC 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 bore 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 17. The MPC Loan Agreement was amended effective January 1, 2023 to update the interest rate to one-month term SOFR adjusted upward by 0.10 percent plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 17. All other terms of the MPC Loan Agreement remain unchanged. Activity on the MPC Loan Agreement was as follows: (In millions, except %) December 31, 2022 December 31, 2021 Borrowings $ 2,989 $ 8,493 Weighted average interest rate of borrowings 1.50 % 1.34 % Repayments $ 4,439 $ 7,043 Outstanding balance at end of period $ — $ 1,450

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Schedule of Stockholders Equity [Table Text Block]	The table below summarizes the changes in the number of units outstanding for the years ended December 31, 2020, 2021, and 2022: (In units) Total Common Units Balance at December 31, 2019 1,058,355,471 Unit-based compensation awards 478,438 Units redeemed in unit repurchase program (1,473,843) Wholesale Exchange (1) (18,582,088) Balance at December 31, 2020 1,038,777,978 Unit-based compensation awards 214,466 Conversion of Series A preferred units 93,108 Units redeemed in unit repurchase program (22,907,174) Balance at December 31, 2021 1,016,178,378 Unit-based compensation awards 190,529 Units redeemed in unit repurchase program (15,348,291) Balance at December 31, 2022 1,001,020,616 (1) In connection with the Wholesale Exchange as discussed in Note 4, MPLX redeemed 18,582,088 units from MPC in exchange for all of the outstanding membership interests in WRW. These units were cancelled by MPLX immediately following the transaction.
Class of Treasury Stock [Table Text Block]	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, which was exhausted during the fourth quarter of 2022. 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. This unit repurchase authorization has no expiration date. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, accelerated unit repurchases, tender offers or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing 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. The table below summarizes the repurchases made under the unit repurchase program for the years ended December 31, 2022, 2021 and 2020: (In millions, except per unit data) 2022 2021 2020 Number of units repurchased 15 23 1 Cash paid for units repurchased (1) $ 491 $ 630 $ 33 Average cost per unit (1) $ 31.96 $ 27.52 $ 22.29 (1) Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period. As of December 31, 2022, we had $846 million available under our remaining unit repurchase authorization.
Distributions Made to Limited Partner, by Distribution [Table Text Block]	The allocation of total quarterly cash distributions to general, limited, and preferred unitholders is as follows for the years ended December 31, 2022, 2021 and 2020. The Partnership Agreement sets forth the calculation to be used to determine the amount and priority of cash distributions that the common unitholders and preferred unitholders will receive. 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. (In millions) 2022 2021 2020 Common and preferred unit distributions: Common unitholders, includes common units of general partner (1) $ 2,980 $ 3,432 $ 2,872 Series A preferred unit distributions (1) 88 100 81 Series B preferred unit distributions 41 41 41 Total cash distributions declared $ 3,109 $ 3,573 $ 2,994 (1) 2021 period includes the Supplemental Distribution Amount.

Net Income (Loss) Per Limited_2

Net Income (Loss) Per Limited Partner Unit (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Schedule of Distributions By Partner By Class [Table Text Block]	(In millions) 2022 2021 2020 Net income/(loss) attributable to MPLX LP (1) $ 3,944 $ 3,077 $ (720) Less: Distributions declared on Series A preferred units (2) 88 100 81 Distributions declared on Series B preferred units 41 41 41 Limited partners’ distributions declared on MPLX common units (including common units of general partner) (2) 2,980 3,432 2,872 Undistributed net income/(loss) attributable to MPLX LP $ 835 $ (496) $ (3,714) (1) The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information. (2) The year ended December 31, 2021 includes the Supplemental Distribution Amount.
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	2022 (In millions, except per unit data) Limited 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 $ 2,980 $ 88 $ 41 $ 3,109 Undistributed net income attributable to MPLX LP 811 24 — 835 Net income attributable to MPLX LP (1) $ 3,791 $ 112 $ 41 $ 3,944 Weighted average units outstanding: Basic 1,010 Diluted 1,010 Net income attributable to MPLX LP per limited partner unit: Basic $ 3.75 Diluted $ 3.75 (1) The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information. 2021 (In millions, except per unit data) Limited 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) $ 3,432 $ 100 $ 41 $ 3,573 Undistributed net loss attributable to MPLX LP (496) — — (496) Net income attributable to MPLX LP $ 2,936 $ 100 $ 41 $ 3,077 Weighted average units outstanding: Basic 1,027 Diluted 1,027 Net income attributable to MPLX LP per limited partner unit: Basic $ 2.86 Diluted $ 2.86 (1) Includes the Supplemental Distribution Amount. 2020 (In millions, except per unit data) Limited Series A Preferred Units Series B Preferred Units Total Basic and diluted net loss attributable to MPLX LP per unit: Net (loss)/income attributable to MPLX LP: Distribution declared $ 2,872 $ 81 $ 41 $ 2,994 Undistributed net loss attributable to MPLX LP (3,714) — — (3,714) Net (loss)/income attributable to MPLX LP $ (842) $ 81 $ 41 $ (720) Weighted average units outstanding: Basic 1,051 Diluted 1,051 Net loss attributable to MPLX LP per limited partner unit: Basic $ (0.80) Diluted $ (0.80)

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 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, restructuring expenses, capital expenditures and investments in unconsolidated affiliates as well as total assets for our reportable segments: (In millions) 2022 2021 2020 L&S Service revenue $ 4,057 $ 3,918 $ 3,889 Rental income 803 772 985 Product related revenue 19 14 51 Sales-type lease revenue 465 435 152 Income from equity method investments 267 153 154 Other income 57 61 54 Total segment revenues and other income (1) 5,668 5,353 5,285 Segment Adjusted EBITDA (2) 3,818 3,681 3,488 Restructuring expenses — — 29 Capital expenditures 325 316 498 Investments in unconsolidated affiliates 97 33 141 G&P Service revenue 2,056 2,023 2,088 Rental income 287 347 365 Product related revenue 2,792 2,066 868 Sales-type lease revenue 62 — — Income/(loss) from equity method investments 209 168 (1,090) Other income (3) 539 70 53 Total segment revenues and other income (1) 5,945 4,674 2,284 Segment Adjusted EBITDA (2) 1,957 1,879 1,723 Restructuring expenses — — 8 Capital expenditures 528 224 441 Investments in unconsolidated affiliates $ 120 $ 118 $ 125 (1) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $644 million, $503 million and $567 million for the years ended December 31, 2022, 2021 and 2020, respectively. Third party revenues for the G&P segment were $5,678 million, $4,463 million and $2,088 million for the years ended December 31, 2022, 2021 and 2020, respectively. (2) See below for the reconciliation from Segment Adjusted EBITDA to Net income/(loss). (3) Includes a $509 million non-cash gain on a lease reclassification for the year ended December 31, 2022. See Note 20 in the Consolidated Financial Statements 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/(loss) and Segment Adjusted EBITDA. (In millions) 2022 2021 2020 Reconciliation to Net income/(loss): L&S Segment Adjusted EBITDA $ 3,818 $ 3,681 $ 3,488 G&P Segment Adjusted EBITDA 1,957 1,879 1,723 Total reportable segments 5,775 5,560 5,211 Depreciation and amortization (1) (1,230) (1,287) (1,377) Interest and other financial costs (925) (879) (896) Income/(loss) from equity method investments 476 321 (936) Distributions/adjustments related to equity method investments (652) (537) (499) Gain on sales-type leases 509 — — Impairment expense — (42) (2,165) Restructuring expenses — — (37) Adjusted EBITDA attributable to noncontrolling interests 38 39 37 Other (2) (13) (63) (25) Net income/(loss) $ 3,978 $ 3,112 $ (687) (1) Depreciation and amortization attributable to L&S was $515 million, $546 million and $633 million for the years ended December 31, 2022, 2021 and 2020, respectively. Depreciation and amortization attributable to G&P was $715 million, $741 million and $744 million for the years ended December 31, 2022, 2021 and 2020, respectively. (2) Includes unrealized derivative gain/(loss), non-cash equity-based compensation, provision for income taxes, and other miscellaneous items.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2022
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consist of the following: December 31, (In millions) 2022 2021 NGLs $ 6 $ 12 Line fill 16 23 Spare parts, materials and supplies 126 107 Total inventories $ 148 $ 142

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment	Property, plant and equipment with associated accumulated depreciation is shown below: Estimated December 31, (In millions) 2022 2021 L&S Pipelines 15-50 years $ 6,323 $ 6,299 Refining logistics 15-20 years 1,710 1,650 Terminals 15-40 years 1,618 1,655 Marine 15-20 years 1,000 965 Land, building and other 5-60 years 1,585 1,589 Construction-in-progress 180 213 Total L&S property, plant and equipment 12,416 12,371 G&P Gathering and transportation 5-40 years 6,781 7,668 Processing and fractionation 10-40 years 5,928 5,795 Land, building and other 5-40 years 511 514 Construction-in-progress 275 198 Total G&P property, plant and equipment 13,495 14,175 Total property, plant and equipment 25,911 26,546 Less accumulated depreciation (1) 7,063 6,504 Property, plant and equipment, net $ 18,848 $ 20,042 (1) Includes property, plant and equipment impairment charges recorded during the respective period, as discussed below.

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	12 Months Ended
	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in carrying amount of goodwill were as follows for the periods presented: (In millions) L&S G&P Total Gross goodwill as of December 31, 2020 $ 7,657 $ 3,141 $ 10,798 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2020 7,657 — 7,657 Impairment losses — — — Balance as of December 31, 2021 7,657 — 7,657 Impairment losses — — — Disposal of assets (12) — (12) Balance as of December 31, 2022 7,645 — 7,645 Gross goodwill as of December 31, 2022 7,645 3,141 10,786 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2022 $ 7,645 $ — $ 7,645
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	MPLX’s intangible assets are comprised of customer contracts and relationships. Gross intangible assets with accumulated amortization as of December 31, 2022 and 2021 is shown below: December 31, 2022 December 31, 2021 (In millions) Useful Life Gross Accumulated Amortization (1) Net Gross Accumulated Amortization (1) Net L&S 6 - 8 years $ 283 $ (153) $ 130 $ 283 $ (117) $ 166 G&P 6 - 25 years 1,288 (713) 575 1,288 (623) 665 $ 1,571 $ (866) $ 705 $ 1,571 $ (740) $ 831 (1) Amortization expense attributable to the L&S segment for both years ended December 31, 2022 and 2021 was $36 million. Amortization expense attributable to the G&P segment for the years ended December 31, 2022 and 2021 was $90 million and $92 million, respectively.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated future amortization expense related to the intangible assets at December 31, 2022 is as follows: (In millions) 2023 $ 127 2024 127 2025 113 2026 104 2027 76 2028 and thereafter 158 Total $ 705

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of changes in Level 3 fair value measurements [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. (In millions) 2022 2021 Beginning balance $ (108) $ (63) Unrealized and realized gain/(loss) included in net income (1) 35 (59) Settlements 12 14 Ending balance (61) (108) The amount of total gain/(loss) for the period included in net income attributable to the change in unrealized gain or loss relating to liabilities still held at end of period $ 33 $ (47) (1) Gain/(loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs on the Consolidated Statements of Income.
Fair 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: December 31, 2022 2021 (In millions) Fair Value Carrying Value Fair Value Carrying Value Outstanding debt (1) $ 18,095 $ 19,905 $ 20,779 $ 18,664 (1) Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below: December 31, (In millions) 2022 2021 Derivative contracts not designated as hedging instruments and their balance sheet location Asset Liability Asset Liability Commodity contracts (1) Other current assets / Other current liabilities $ — $ 10 $ — $ 15 Other noncurrent assets / Other long-term liabilities — 51 — 93 Total $ — $ 61 $ — $ 108 (1) Includes the embedded derivative in the commodity contract discussed above.
Derivative Instruments, Gain (Loss) [Table Text Block]	The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below: (In millions) 2022 2021 2020 Purchased product costs Realized loss $ (12) $ (14) $ (6) Unrealized gain/(loss) 47 (45) (3) Purchased product cost derivative gain/(loss) $ 35 $ (59) $ (9)

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2022
Extinguishment of Debt [Line Items]
Schedule of Debt [Table Text Block]	MPLX’s outstanding borrowings at December 31, 2022 and 2021 consisted of the following: December 31, (In millions) 2022 2021 MPLX LP: Bank revolving credit facility $ — $ 300 3.500% senior notes due December 1, 2022 — 486 3.375% senior notes due March 15, 2023 — 500 4.500% senior notes due July 15, 2023 989 989 4.875% senior notes due December 1, 2024 1,149 1,149 4.000% senior notes due February 15, 2025 500 500 4.875% senior notes due June 1, 2025 1,189 1,189 1.750% senior notes due March 1, 2026 1,500 1,500 4.125% senior notes due March 1, 2027 1,250 1,250 4.250% senior notes due December 1, 2027 732 732 4.000% senior notes due March 15, 2028 1,250 1,250 4.800% senior notes due February 15, 2029 750 750 2.650% senior notes due August 15, 2030 1,500 1,500 4.950% senior notes due September 1, 2032 1,000 — 4.500% senior notes due April 15, 2038 1,750 1,750 5.200% senior notes due March 1, 2047 1,000 1,000 5.200% senior notes due December 1, 2047 487 487 4.700% senior notes due April 15, 2048 1,500 1,500 5.500% senior notes due February 15, 2049 1,500 1,500 4.950% senior notes due March 14, 2052 1,500 — 4.900% senior notes due April 15, 2058 500 500 Consolidated subsidiaries: MarkWest - 4.500% - 4.875% senior notes, due 2023-2025 23 23 ANDX - 3.500% - 5.200% senior notes, due 2027-2047 31 45 Financing lease obligations (1) 8 9 Total 20,108 18,909 Unamortized debt issuance costs (117) (102) Unamortized discount (195) (236) Amounts due within one year (988) (499) Total long-term debt due after one year $ 18,808 $ 18,072 (1) See Note 20 for lease information.
Schedule of Maturities of Long-Term Debt [Table Text Block]	The following table shows five years of scheduled debt payments, including payments on finance lease obligations, as of December 31, 2022: (In millions) 2023 $ 1,002 2024 1,152 2025 1,701 2026 1,501 2027 $ 2,001
Schedule of interest payable dates [Table Text Block]	Interest on each series of MPLX LP, MarkWest and ANDX senior notes is payable semi-annually in arrears, according to the table below. Senior Notes Interest payable semi-annually in arrears 4.500% senior notes due July 15, 2023 January 15 th and July 15 th 4.875% senior notes due December 1, 2024 June 1 st and December 1 st 4.000% senior notes due February 15, 2025 February 15 th and August 15 th 4.875% senior notes due June 1, 2025 June 1 st and December 1 st 1.750% senior notes due March 1, 2026 March 1 st and September 1 st 4.125% senior notes due March 1, 2027 March 1 st and September 1 st 4.250% senior notes due December 1, 2027 June 1 st and December 1 st 4.000% senior notes due March 15, 2028 March 15 th and September 15 th 4.800% senior notes due February 15, 2029 February 15 th and August 15 th 2.650% senior notes due August 15, 2030 February 15 th and August 15 th 4.950% senior notes due September 1, 2032 March 1 st and September 1 st 4.500% senior notes due April 15, 2038 April 15 th and October 15 th 5.200% senior notes due March 1, 2047 March 1 st and September 1 st 5.200% senior notes due December 1, 2047 June 1 st and December 1 st 4.700% senior notes due April 15, 2048 April 15 th and October 15 th 5.500% senior notes due February 15, 2049 February 15 th and August 15 th 4.950% senior notes due March 14, 2052 March 14 th and September 14 th 4.900% senior notes due April 15, 2058 April 15 th and October 15 th
Schedule of Long-term Debt Instruments [Table Text Block]	Activity on the new and previous MPLX Credit Agreement was as follows: (In millions, except %) December 31, 2022 December 31, 2021 Borrowings $ 900 $ 4,175 Weighted average interest rate of borrowings 1.45 % 1.34 % Repayments $ 1,200 $ 4,050 Outstanding balance at end of period $ — $ 300 Letters of credit outstanding $ 0.2 $ 0.2 Total remaining availability on facility $ 2,000 $ 3,200 Percent of borrowing capacity available 100 % 91 %

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 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 years ended December 31, 2022, 2021 and 2020: 2022 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 320 $ 2,039 $ 2,359 Service revenue - related parties 3,737 17 3,754 Service revenue - product related — 394 394 Product sales 6 2,213 2,219 Product sales - related parties 13 185 198 Total revenues from contracts with customers $ 4,076 $ 4,848 8,924 Non-ASC 606 revenue (1) 2,689 Total revenues and other income $ 11,613 2021 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 310 $ 2,003 $ 2,313 Service revenue - related parties 3,608 20 3,628 Service revenue - product related — 345 345 Product sales 4 1,586 1,590 Product sales - related parties 10 135 145 Total revenues from contracts with customers $ 3,932 $ 4,089 8,021 Non-ASC 606 revenue (1) 2,006 Total revenues and other income $ 10,027 2020 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 333 $ 2,064 $ 2,397 Service revenue - related parties 3,556 24 3,580 Service revenue - product related — 155 155 Product sales 39 597 636 Product sales - related parties 12 116 128 Total revenues from contracts with customers $ 3,940 $ 2,956 6,896 Non-ASC 606 revenue (1) 673 Total revenues and other income $ 7,569
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]	The tables below reflect the changes in ASC 606 contract balances for the years ended December 31, 2022 and 2021: (In millions) Balance at Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 25 $ (4) $ — $ 21 Long-term contract assets 2 (1) — 1 Deferred revenue 56 41 (40) 57 Deferred revenue - related parties 60 109 (106) 63 Long-term deferred revenue 135 81 — 216 Long-term deferred revenue - related parties 31 (6) — 25 Long-term contract liabilities $ 5 $ (3) $ — $ 2 (In millions) Balance at Additions/ (Deletions) Revenue Recognized(1) Balance at Contract assets $ 40 $ (15) $ — $ 25 Long-term contract assets 2 — — 2 Deferred revenue 37 56 (37) 56 Deferred revenue - related parties 91 75 (106) 60 Long-term deferred revenue 119 16 — 135 Long-term deferred revenue - related parties 48 (17) — 31 Long-term contract liabilities $ 6 $ (1) $ — $ 5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	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 December 31, 2022, unsatisfied performance obligations included in the Consolidated Balance Sheets are $360 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. Additionally, we do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less. (In millions) 2023 $ 1,844 2024 1,717 2025 1,634 2026 1,471 2027 1,330 2028 and thereafter 733 Total revenue on remaining performance obligations (1)(2)(3) $ 8,729 (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.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Summary of Supplemental Cash Flow Information	(In millions) 2022 2021 2020 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 813 $ 812 $ 821 Income taxes paid 3 4 2 Cash paid for amounts included in the measurement of lease liabilities Payments on operating leases 73 79 87 Interest payment under finance lease obligations — — 1 Net cash provided by financing activities included: Principal payments under finance lease obligations 2 2 9 Non-cash investing and financing activities: Net transfers of property, plant and equipment (to)/from materials and supplies inventories (1) 1 — ROU assets obtained in exchange for new operating lease obligations 78 20 17 ROU assets obtained in exchange for new finance lease obligations 1 — 1 Fair value of common units redeemed for Wholesale Exchange — — 340
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 did not affect cash. The following is a reconciliation of additions to property, plant and equipment to total capital expenditure: (In millions) 2022 2021 2020 Additions to property, plant and equipment $ 806 $ 529 $ 1,183 Increase/(decrease) in capital accruals 47 11 (244) Total capital expenditures $ 853 $ 540 $ 939

Leases Lessee Disclosure (Table

Leases Lessee Disclosure (Tables)	12 Months Ended
	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Lease, Cost [Table Text Block]	The components of lease cost were as follows: 2022 2021 2020 (In millions) Related Party Third Related Third Related Third Components of lease costs: Operating lease costs $ 15 $ 61 $ 15 $ 71 $ 14 $ 78 Finance lease cost: Amortization of ROU assets — 1 — 2 — 3 Interest on lease liabilities — 1 — 1 — 1 Total finance lease cost — 2 — 3 — 4 Variable lease cost 2 16 — 15 1 10 Short-term lease cost — 45 — 31 — 52 Total lease cost $ 17 $ 124 $ 15 $ 120 $ 15 $ 144
Supplemental Balance Sheet Disclosures [Text Block]	Supplemental balance sheet data related to leases were as follows: December 31, 2022 December 31, 2021 (In millions, except % and years) Related Party Third Party Related Party Third Party Operating leases Assets Right of use assets $ 228 $ 283 $ 229 $ 268 Liabilities Operating lease liabilities 1 46 1 59 Long-term operating lease liabilities 228 230 228 205 Total operating lease liabilities $ 229 $ 276 $ 229 $ 264 Weighted average remaining lease term 44.2 years 9.2 years 45.2 years 8.3 years Weighted average discount rate 5.8 % 4.1 % 5.8 % 4.1 % Finance leases Assets Property, plant and equipment, gross $ 11 $ 11 Less: Accumulated depreciation 4 4 Property, plant and equipment, net 7 7 Liabilities Long-term debt due within one year 1 2 Long-term debt 7 7 Total finance lease liabilities $ 8 $ 9 Weighted average remaining lease term 18.4 years 19.4 years Weighted average discount rate 6.0 % 6.0 %
Schedule of Future Minimum Lease Payments for Operating and Finance Leases [Table Text Block]	As of December 31, 2022, maturities of lease liabilities for operating lease obligations and finance lease obligations having initial or remaining non-cancellable lease terms in excess of one year are as follows: (In millions) Related Party Operating Third Party Operating Finance 2023 $ 15 $ 56 $ 2 2024 15 46 2 2025 14 34 1 2026 14 30 1 2027 14 29 1 2028 and thereafter 561 135 7 Gross lease payments 633 330 14 Less: Imputed interest 404 54 6 Total lease liabilities $ 229 $ 276 $ 8
Operating Lease, Lease Income [Table Text Block]	Lease revenues included on the Consolidated Statements of Income during 2022, 2021 and 2020 were as follows: 2022 2021 2020 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 763 $ 327 $ 743 $ 376 $ 952 $ 398 Sales-type leases: Interest income (Sales-type rental revenue- fixed minimum) 447 46 431 — 151 — Interest income (Revenue from variable lease payments) 18 16 4 — 1 — Sales-type lease revenue $ 465 $ 62 $ 435 $ — $ 152 $ —
Sales-type Lease, Lease Income [Table Text Block]	Lease revenues included on the Consolidated Statements of Income during 2022, 2021 and 2020 were as follows: 2022 2021 2020 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 763 $ 327 $ 743 $ 376 $ 952 $ 398 Sales-type leases: Interest income (Sales-type rental revenue- fixed minimum) 447 46 431 — 151 — Interest income (Revenue from variable lease payments) 18 16 4 — 1 — Sales-type lease revenue $ 465 $ 62 $ 435 $ — $ 152 $ —
Lessor, Operating Lease, Payment to be Received, Fiscal Year Maturity [Table Text Block]	The following is a schedule of minimum future rental revenue on the non-cancellable operating leases as of December 31, 2022: (In millions) Related Party Third Party Total 2023 $ 627 $ 97 $ 724 2024 569 95 664 2025 546 64 610 2026 446 37 483 2027 330 16 346 2028 and thereafter 149 21 170 Total minimum future rentals $ 2,667 $ 330 $ 2,997
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 December 31, 2022: (In millions) Related Party Third Party Total 2023 $ 489 $ 169 $ 658 2024 489 156 645 2025 489 146 635 2026 459 137 596 2027 357 128 485 2028 and thereafter 214 970 1,184 Total minimum future rentals 2,497 1,706 4,203 Less: present value discount 1,503 765 2,268 Lease receivable (1) $ 994 941 1,935 Current lease receivables (2) 111 98 209 Long-term lease receivables (3) 883 843 1,726 Unguaranteed residual assets (3) 87 66 153 Total sales-type lease assets $ 1,081 $ 1,007 $ 2,088 (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.
Schedule of Property Subject to or Available for Operating Lease [Table Text Block]	The following schedule summarizes MPLX’s investment in assets held under operating lease by major classes as of December 31, 2022 and 2021: December 31, (In millions) 2022 2021 Pipelines $ 670 $ 953 Refining logistics 1,310 1,146 Terminals 1,241 1,290 Marine 126 129 Gathering and transportation 94 991 Processing and fractionation 973 867 Land, building and other 163 176 Total property, plant and equipment 4,577 5,552 Less: accumulated depreciation 1,880 2,042 Property, plant and equipment, net $ 2,697 $ 3,510

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule	MPLX executed various third-party transportation and terminalling agreements that obligate us to minimum volume, throughput or payment commitments over the remaining terms of the agreements, which range from less than one year to nine years. After the minimum volume commitments are met in the transportation and terminalling agreements, MPLX pays additional amounts based on throughput. There are escalation clauses in the transportation and terminalling agreements, which are based on Consumer Price Index adjustments. The minimum future payments under these agreements as of December 31, 2022 are as follows: (In millions) 2023 $ 162 2024 152 2025 128 2026 118 2027 114 2028 and thereafter 204 Total $ 878

Description of Business and B_3

Description of Business and Basis of Presentation (Details)				12 Months Ended
	Jul. 31, 2020 shares	Oct. 31, 2012	Mar. 27, 2012	Dec. 31, 2022
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Date of partnership formation			Mar. 27, 2012
Date for initial public offering completed		Oct. 31, 2012
Number of reportable segments				2
Western Refining Wholesale & Western Refining Product Transport [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Partners' Capital Account, Units, Redeemed	18,582,088

Summary of Principal Accounti_3

Summary of Principal Accounting Policies (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Asset Retirement Obligation	$ 34	$ 31
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Deferred Credits and Other Liabilities, Noncurrent, Other Liabilities, Current	Deferred Credits and Other Liabilities, Noncurrent, Other Liabilities, Current

Javelina Disposition (Details)

Javelina Disposition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Gain (Loss) on Disposition of Assets	$ (34)	$ 13	$ (4)
Sale of Javelina Assets and Liabilities
Business Acquisition [Line Items]
Gain (Loss) on Disposition of Assets		$ 0

Wholesale Exchange (Details)

Wholesale Exchange (Details) - USD ($) $ in Millions	Jul. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill		$ 7,645	$ 7,657	$ 7,657
Western Refining Wholesale & Western Refining Product Transport [Member]
Business Acquisition [Line Items]
Partners' Capital Account, Units, Redeemed	18,582,088
Partner Capital, Units, contributed, fair value assigned	$ 340
Fair Value, Net Asset (Liability)	90
Excess of Fair Value over Book Value	250
Goodwill	$ 65

Investments and Noncontrollin_3

Investments and Noncontrolling Interest (Equity Method Investments) (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity Method Investments		$ 4,095	$ 3,981
Sherwood Midstream Holdings | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.55%
Logistics and Storage [Member]
Schedule of Equity Method Investments [Line Items]
Basis difference, not amortized		$ 167	167
Basis difference		$ 320	327
Logistics and Storage [Member] | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67%
Equity Method Investments		$ 177	183
Logistics and Storage [Member] | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41%
Equity Method Investments		$ 287	265
Logistics and Storage [Member] | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35%
Equity Method Investments		$ 236	243
Logistics and Storage [Member] | MarEn Bakken
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	[1]	25%
Equity Method Investments	[1]	$ 475	449
Logistics and Storage [Member] | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17%
Equity Method Investments		$ 178	183
Logistics and Storage [Member] | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38%
Equity Method Investments		$ 211	155
Logistics and Storage [Member] | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	[2]	$ 269	240
Logistics and Storage [Member] | Bakken Pipeline System | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		9.19%
Gathering and Processing [Member]
Schedule of Equity Method Investments [Line Items]
Basis difference, not amortized		$ 31	31
Basis difference		$ (51)	(54)
Gathering and Processing [Member] | Centrahoma Processing LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40%
Equity Method Investments		$ 131	133
Gathering and Processing [Member] | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67%
Equity Method Investments		$ 335	332
Gathering and Processing [Member] | MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		60%
Equity Method Investments		$ 306	246
Gathering and Processing [Member] | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57%
Equity Method Investments		$ 669	680
Gathering and Processing [Member] | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		78%
Equity Method Investments		$ 137	147
Gathering and Processing [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity Method Investments		$ 125	136
Gathering and Processing [Member] | Sherwood Midstream Holdings | Direct Ownership Interest
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		51%
Gathering and Processing [Member] | Sherwood Midstream LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50%
Equity Method Investments		$ 512	544
Gathering and Processing [Member] | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	[2]	47	45
Operating Segments | Logistics and Storage [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments		1,833	1,718
Operating Segments | Gathering and Processing [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments		$ 2,262	$ 2,263
[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]Some investments included within Other have also been deemed to be VIEs.

Investments and Noncontrollin_4

Investments and Noncontrolling Interests (Summary of Equity Method Investment Financial Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Revenues	$ 11,613	$ 10,027		$ 7,569
Total costs and expenses	6,702	6,035		7,358
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	3,978	3,112		(687)
Income (Loss) from Equity Method Investments	476	321	[1]	(936)	[1]
Assets, Current	1,905	1,507
Liabilities, Current	2,401	3,348
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Other than Temporary Impairment				1,251
Other VIEs
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments	275	175	[1]	(1,100)	[1]
Non-VIEs
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments	201	146	[1]	164	[1]
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues	2,653	2,056		1,506
Total costs and expenses	1,251	1,058		945
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	1,402	998		561
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	1,246	860		440
Assets, Current	924	746
Assets, Noncurrent	12,946	12,334
Liabilities, Current	504	527
Liabilities, Noncurrent	3,422	3,249
Income (Loss) from Equity Method Investments from Asset Impairment		6		1,264
Non-VIEs
Schedule of Equity Method Investments [Line Items]
Revenues	1,456	1,236		1,208
Total costs and expenses	648	568		531
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	808	668		677
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	711	594		615
Assets, Current	450	411
Assets, Noncurrent	5,225	4,895
Liabilities, Current	181	310
Liabilities, Noncurrent	876	788
Other VIEs
Schedule of Equity Method Investments [Line Items]
Revenues	1,197	820		298
Total costs and expenses	603	490		414
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	594	330		(116)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	535	266		$ (175)
Assets, Current	474	335
Assets, Noncurrent	7,721	7,439
Liabilities, Current	323	217
Liabilities, Noncurrent	$ 2,546	$ 2,461
[1]The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively.

Investments and Noncontrollin_5

Investments and Noncontrolling Interests (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments from Asset Impairment	$ 6	$ 1,264
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Other than Temporary Impairment		$ 1,251
Sherwood Midstream Holdings | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			24.55%
Gathering and Processing [Member]
Schedule of Equity Method Investments [Line Items]
Basis difference	(54)		$ (51)
Basis difference, not amortized	31		$ 31
Gathering and Processing [Member] | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			57%
Gathering and Processing [Member] | Sherwood Midstream LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			50%
Logistics and Storage [Member]
Schedule of Equity Method Investments [Line Items]
Basis difference	327		$ 320
Basis difference, not amortized	$ 167		$ 167

Related Party Agreements and _3

Related Party Agreements and Transactions (Narrative) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Commercial Agreements
Restructuring Charges	$ 0	$ 0	$ 37
Marathon Petroleum Corporation [Member]
Commercial Agreements
Restructuring Charges	$ 0	$ 0	$ 37
Marathon Petroleum Corporation [Member] | Fuels Distribution [Member]
Commercial Agreements
Term Of Agreements	10 years
Renewal Term Agreement	5 years
Marathon Petroleum Corporation [Member] | Marine Services Equipment [Member]
Commercial Agreements
Term Of Agreements	6 years
Automatic renewal term agreement	5 years
Number of renewals	2
Marathon Petroleum Corporation [Member] | Co-location Agreements [Member]
Commercial Agreements
Term Of Agreements	50 years
Commercial Agreements | Marathon Petroleum Corporation [Member] | Marine Management Services [Member]
Commercial Agreements
Term Of Agreements	5 years
Automatic renewal term agreement	5 years
Number of renewals	1
Operating Agreements [Member] | Marathon Petroleum Corporation [Member] | Minimum
Commercial Agreements
Term Of Agreements	1 year
Operating Agreements [Member] | Marathon Petroleum Corporation [Member] | Maximum
Commercial Agreements
Term Of Agreements	5 years

Related Party Agreements and _4

Related Party Agreements and Transactions (Intercompany Loans with Related Parties) (Detail) - Related Party Revolving Credit Agreement - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Repayments of Related Party Debt		$ 4,439	$ 7,043	$ 6,858
Proceeds from Related Party Debt		2,989	$ 8,493	$ 6,264
MPC Investment
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
Interest rate during period		1.50%	1.34%
Line of Credit, Current		$ 0	$ 1,450
MPC Investment | Subsequent Event
Related Party Transaction [Line Items]
Debt Instrument, Description of Variable Rate Basis	one-month term SOFR adjusted upward by 0.10 percent plus 1.25 percent

Related Party Agreements and _5

Related Party Agreements and Transactions (Summary of Revenue by Income Statement RP Line Item) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Sales Revenue, Goods, Related Party, Net Zero	$ 1,002	$ 811	$ 462

Related Party Agreements and _6

Related Party Agreements and Transactions (Summary of Expenses by Income Statement RP Line Item) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) employees
Related Party Transaction [Line Items]
Restructuring Charges	$ 0	$ 0	$ 37
General and Administrative Expense	335	353	378
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Restructuring Charges	0	0	37
General and Administrative Expense	235	250	$ 254
Restructuring and Related Cost, Number of Positions Eliminated | employees			2,050
Construction-in-progress | Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 70	$ 55	$ 97

Related Party Agreements and _7

Related Party Agreements and Transactions (Summary of Balance Sheet by RP Line Item) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Aug. 01, 2022	Apr. 30, 2021	Mar. 31, 2020
Related Party Transaction [Line Items]
Net Investment in Lease, Current	[1]	$ 209
Due from Related Parties, Noncurrent		1,225	$ 1,161
Net Investment in Lease, Noncurrent	[2]	1,726
Sales-type Lease, Unguaranteed Residual Asset	[2]	153
Due to Related Parties, Current		343	1,780
Deferred Revenue, Noncurrent		219	383
Due from Related Parties, Current		729	644
Due to Related Parties, Noncurrent		338	302
Asset and Inventory transfers
Related Party Transaction [Line Items]
Revenue from related parties		25	26	$ 10
Purchases from related parties		31
Other Affiliates [Member]
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	[3]	262	1,702
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Net Investment in Lease, Current	[1]	111
Operating Lease, Right-of-Use Asset		228	229
Net Investment in Lease, Noncurrent	[2]	883
Sales-type Lease, Unguaranteed Residual Asset	[2]	87
Operating Lease, Liability, Current		1	1
Operating Lease, Liability, Noncurrent, Related Party		228	228
Affiliated Entity
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties, Current		610	555
Prepaid Expense, Current		5	4
Other Assets, Current		3	3
Net Investment in Lease, Current		111	82
Net Investment in Lease, Noncurrent		883	854
Sales-type Lease, Unguaranteed Residual Asset		87	47		$ 6	$ 14	$ 10
Due to Related Parties, Current		343	1,780
Operating Lease, Liability, Current		1	1
Deferred Revenue, Noncurrent					$ 0	$ 0	$ 0
Accounts Receivable, Related Parties, Noncurrent		27	31
Due to Related Parties, Noncurrent		338	302
Operating Lease, Right-of-Use Asset, Related Party		228	229
Deferred Revenue, Current		80	77
Affiliated Entity | Reimbursable Projects and Minimum Volume Deficiency Credits
Related Party Transaction [Line Items]
Deferred Revenue, Noncurrent		$ 110	$ 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. There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2022.

Repurchase Program (Details)

Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Aug. 02, 2022	Nov. 02, 2020	Dec. 31, 2019
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 846
Stock Repurchased and Retired During Period, Value		$ 491	$ 630	$ 33
Stock Repurchase Program, Authorized Amount					$ 1,000	$ 1,000
Units outstanding		1,001,020,616	1,016,178,378	1,038,777,978			1,058,355,471
Payments for Repurchase of Common Stock		$ 491	$ 630	$ 33
Limited Partners Common Units
Equity, Class of Treasury Stock [Line Items]
Partners' Capital Account, Units		15,348,291	22,907,174	1,473,843
Treasury Stock Acquired, Average Cost Per Share	[1]	$ 31.96	$ 27.52	$ 22.29
Payments for Repurchase of Common Stock	[1]	$ 491	$ 630	$ 33
[1]Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period.

Equity (Changes in Partners Cap

Equity (Changes in Partners Capital, Unit Rollforward) (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
		Jul. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stockholders Equity [Line Items]
Payments for Repurchase of Common Stock			$ 491	$ 630	$ 33
Units outstanding			1,001,020,616	1,016,178,378	1,038,777,978	1,058,355,471
Western Refining Wholesale & Western Refining Product Transport [Member]
Stockholders Equity [Line Items]
Partners' Capital Account, Units, Redeemed		(18,582,088)
Limited Partners Common Units
Stockholders Equity [Line Items]
Unit-based compensation awards, in units			190,529	214,466	478,438
Unit conversion				93,108
Partners' Capital Account, Units, Redeemed					(18,582,088)
Stock Repurchased and Retired During Period, Shares			(15,348,291)	(22,907,174)	(1,473,843)
Payments for Repurchase of Common Stock	[1]		$ 491	$ 630	$ 33
Treasury Stock Acquired, Average Cost Per Share	[1]		$ 31.96	$ 27.52	$ 22.29
Limited Partners Common Units | Marathon Petroleum Corporation [Member]
Stockholders Equity [Line Items]
Units outstanding			647,415,452	647,000,000
[1]Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period.

Equity (Cash Distributions) (De

Equity (Cash Distributions) (Details) - USD ($) $ / shares in Units, $ in Millions							12 Months Ended
	Feb. 14, 2023	Feb. 06, 2023	Jan. 25, 2023	Aug. 15, 2022	Feb. 15, 2022	Oct. 26, 2021	Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2020
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared							$ 3,109	$ 3,573		$ 2,994
Distribution Made to Limited Partner, Distributions Declared, Per Unit							$ 2.96	$ 3.36	[1]	$ 2.75
Partners' Capital Account, Distributions							$ 3,000	$ 3,512		$ 2,959
Special Distribution
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Distributions Declared, Per Unit						$ 0.575
Series B Preferred Stock [Member]
Distribution Made to Limited Partner [Line Items]
Distribution made to limited partner, distribution date				Aug. 15, 2022	Feb. 15, 2022
Partners' Capital Account, Distributions				$ 21	$ 21
Subsequent Event
Distribution Made to Limited Partner [Line Items]
Distribution made to limited partner, declaration date			Jan. 25, 2023
Distribution Made to Limited Partner, Distributions Declared, Per Unit			$ 0.7750
Distribution made to limited partner, date of record		Feb. 06, 2023
Subsequent Event | Limited Partners Common Units
Distribution Made to Limited Partner [Line Items]
Distribution made to limited partner, distribution date	Feb. 14, 2023
Limited Partners Common Units
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared							2,980	3,432	[1],[2]	2,872
Limited Partners Common Units | Marathon Petroleum Corporation [Member]
Distribution Made to Limited Partner [Line Items]
Partners' Capital Account, Distributions							1,871	2,163		1,799
Limited Partners Common Units | Subsequent Event
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared			$ 776
Preferred Partner [Member] | Series B Preferred Stock [Member]
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared							41	41		41
Preferred Partner [Member] | Series A Preferred Stock [Member]
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared							$ 88	$ 100	[1],[2]	$ 81
[1]2021 period includes the Supplemental Distribution Amount.On January 25, 2023, MPLX declared a quarterly cash distribution, based on the results of the fourth quarter of 2022, totaling $776 million, or $0.7750 per common unit. This rate was also received by Series A preferred unitholders. These distributions were paid on February 14, 2023 to unitholders of record on February 6, 2023.[2]The year ended December 31, 2021 includes the Supplemental Distribution Amount.

Wholesale Exchange and Merger (

Wholesale Exchange and Merger (Details) - shares		12 Months Ended
	Jul. 31, 2020	Dec. 31, 2020
Limited Partners Common Units
Partners' Capital Account, Units, Redeemed		18,582,088
Western Refining Wholesale & Western Refining Product Transport [Member]
Partners' Capital Account, Units, Redeemed	18,582,088

Series B Preferred Units (Detai

Series B Preferred Units (Details) - Series B Preferred Stock [Member] - $ / shares		12 Months Ended
	Feb. 15, 2023	Dec. 31, 2022
Preferred Units, Outstanding		600,000
Preferred Stock, Dividend Rate, Percentage		6.875%
Units issued, price per unit		$ 1,000
Subsequent Event
Preferred Stock, Redemption Price Per Share	$ 1,000
Preferred Stock, Redemption Terms	MPLX exercised its right to redeem all of the Series B preferred units. MPLX paid unitholders the Series B preferred unit redemption price of $1,000 per unit.

Net Income (Loss) Per Limited_3

Net Income (Loss) Per Limited Partner Unit (Schedule of Distributions by Partner Class) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Net Income Per Share [Line Items]
Net income/(loss) attributable to MPLX LP(1)	$ 3,944	[1]	$ 3,077		$ (720)
Total cash distributions declared	3,109		3,573		2,994
Undistributed net income/(loss) attributable to MPLX LP	835		(496)		(3,714)
Limited Partners Common Units
Net Income Per Share [Line Items]
Total cash distributions declared	2,980		3,432	[2],[3]	2,872
Series A Preferred Stock [Member] | Preferred Partner [Member]
Net Income Per Share [Line Items]
Net income/(loss) attributable to MPLX LP(1)	112	[1]	100		81
Total cash distributions declared	88		100	[2],[3]	81
Series B Preferred Stock [Member] | Preferred Partner [Member]
Net Income Per Share [Line Items]
Net income/(loss) attributable to MPLX LP(1)	41	[1]	41		41
Total cash distributions declared	$ 41		$ 41		$ 41
[1]The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information.[2]2021 period includes the Supplemental Distribution Amount.On January 25, 2023, MPLX declared a quarterly cash distribution, based on the results of the fourth quarter of 2022, totaling $776 million, or $0.7750 per common unit. This rate was also received by Series A preferred unitholders. These distributions were paid on February 14, 2023 to unitholders of record on February 6, 2023.[3]The year ended December 31, 2021 includes the Supplemental Distribution Amount.

Net Income (Loss) Per Limited_4

Net Income (Loss) Per Limited Partner Unit (Basic and Diluted Earnings Per Unit) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Net income attributable to MPLX LP:
Total cash distributions declared	$ 3,109		$ 3,573		$ 2,994
Undistributed net income loss attributable to MPLX LP	835		(496)		(3,714)
Net income/(loss) attributable to MPLX LP(1)	$ 3,944	[1]	$ 3,077		$ (720)
Weighted average units outstanding:
Basic (shares)	1,010		1,027		1,051
Diluted (shares)	1,010		1,027		1,051
Net income attributable to MPLX LP subsequent to initial public offering per limited partner unit:
Basic (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Diluted (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1		1		1
Other Income [Member]
Net income attributable to MPLX LP subsequent to initial public offering per limited partner unit:
Sales-type Lease, Selling Profit (Loss)	$ 509		$ 0		$ 0
Limited Partners Common Units
Net income attributable to MPLX LP:
Total cash distributions declared	$ 2,980		$ 3,432	[2],[3]	$ 2,872
Weighted average units outstanding:
Basic (shares)	1,010		1,027		1,051
Diluted (shares)	1,010		1,027		1,051
Net income attributable to MPLX LP subsequent to initial public offering per limited partner unit:
Basic (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Diluted (in USD per unit)	$ 3.75		$ 2.86		$ (0.80)
Series A Preferred Stock [Member] | Preferred Partner [Member]
Net income attributable to MPLX LP:
Total cash distributions declared	$ 88		$ 100	[2],[3]	$ 81
Undistributed net income loss attributable to MPLX LP	24		0		0
Net income/(loss) attributable to MPLX LP(1)	112	[1]	100		81
Series B Preferred Stock [Member] | Preferred Partner [Member]
Net income attributable to MPLX LP:
Total cash distributions declared	41		41		41
Undistributed net income loss attributable to MPLX LP	0		0		0
Net income/(loss) attributable to MPLX LP(1)	41	[1]	41		41
Common Stock | Limited Partners Common Units
Net income attributable to MPLX LP:
Total cash distributions declared	2,980		3,432	[3]	2,872
Undistributed net income loss attributable to MPLX LP	811		(496)		(3,714)
Net income/(loss) attributable to MPLX LP(1)	$ 3,791	[1]	$ 2,936		$ (842)
[1]The year ended December 31, 2022 includes a $509 million non-cash gain on a lease reclassification. See Note 20 for additional information.[2]2021 period includes the Supplemental Distribution Amount.On January 25, 2023, MPLX declared a quarterly cash distribution, based on the results of the fourth quarter of 2022, totaling $776 million, or $0.7750 per common unit. This rate was also received by Series A preferred unitholders. These distributions were paid on February 14, 2023 to unitholders of record on February 6, 2023.[3]The year ended December 31, 2021 includes the Supplemental Distribution Amount.

Redeemable Preferred Units (Nar

Redeemable Preferred Units (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Jan. 25, 2023	May 13, 2016	Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2020
Redeemable Noncontrolling Interest [Line Items]
Distribution Made to Limited Partner, Distributions Declared, Per Unit			$ 2.96	$ 3.36	[1]	$ 2.75
Limited Partners Common Units
Redeemable Noncontrolling Interest [Line Items]
Partners' Capital Account, Units, Converted				93,108
Series A Preferred Stock [Member] | Preferred Partner [Member]
Redeemable Noncontrolling Interest [Line Items]
Preferred Stock, Dividend Rate, Percentage		6.50%
Units issued, price per unit		$ 32.50
Issuance of redeemable preferred units		$ 984
Preferred units, dividend rate, per-dollar-amount		$ 0.528125
Preferred units, description		The holders may convert their Series A preferred units into common units at any time, in full or in part, subject to minimum conversion amounts and conditions. After the fourth anniversary of the issuance date, MPLX may convert the Series A preferred units into common units at any time, in whole or in part, subject to certain minimum conversion amounts and conditions, if the closing price of MPLX common units is greater than $48.75 for the 20-day trading period immediately preceding the conversion notice date. The conversion rate for the Series A preferred units shall be the quotient of (a) the sum of (i) $32.50, plus (ii) any unpaid cash distributions on the applicable preferred unit, divided by (b) $32.50, subject to adjustment for unit distributions, unit splits and similar transactions. The holders of the Series A preferred units are entitled to vote on an as-converted basis with the common unitholders and have certain other class voting rights with respect to any amendment to the MPLX partnership agreement that would adversely affect any rights, preferences or privileges of the preferred units. In addition, upon certain events involving a change of control, the holders of preferred units may elect, among other potential elections, to convert their Series A preferred units to common units at the then applicable change of control conversion rate.
Temporary Equity, Shares Issued		30,800,000	30,000,000	30,000,000
Temporary Equity, Shares Outstanding			29,500,000	30,000,000
Subsequent Event
Redeemable Noncontrolling Interest [Line Items]
Distribution made to limited partner, declaration date	Jan. 25, 2023
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.7750
[1]2021 period includes the Supplemental Distribution Amount.On January 25, 2023, MPLX declared a quarterly cash distribution, based on the results of the fourth quarter of 2022, totaling $776 million, or $0.7750 per common unit. This rate was also received by Series A preferred unitholders. These distributions were paid on February 14, 2023 to unitholders of record on February 6, 2023.

Segment Information (Details)

Segment Information (Details)	12 Months Ended
	Dec. 31, 2022
Segment Reporting Information [Line Items]
Number of reportable segments	2

Segment Information - Revenues

Segment Information - Revenues and Adjusted EBITDA (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Lease, Lease Income		$ 327		$ 376		$ 398
Sales-type Lease, Revenue		62		0		0
Income (Loss) from Equity Method Investments		476		321	[1]	(936)	[1]
Restructuring Charges		0		0		37
Capital Expenditure		853		540		939
Investments in unconsolidated affiliates		(217)		(151)		(266)
Total segment revenues and other income		11,613		10,027		7,569
Other Income [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-type Lease, Selling Profit (Loss)		509		0		0
Marathon Petroleum Corporation [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-type Lease, Revenue		465		435		152
Restructuring Charges		0		0		37
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		8,924		8,021		6,896
Adjusted EBITDA		5,775		5,560		5,211
Segment Reconciling Items
Segment Reporting, Revenue Reconciling Item [Line Items]
Income (Loss) from Equity Method Investments		476		321		(936)
Restructuring Charges		0		0		(37)
Sales-type Lease, Selling Profit (Loss)		509		0		0
Logistics and Storage [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,076		3,932		3,940
Logistics and Storage [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Lease, Lease Income		803		772		985
Sales-type Lease, Revenue		465		435		152
Income (Loss) from Equity Method Investments		267		153		154
Other Operating Income		57		61		54
Adjusted EBITDA		3,818		3,681		3,488
Restructuring Charges		0		0		29
Capital Expenditure		325		316		498
Investments in unconsolidated affiliates		(97)		(33)		(141)
Total segment revenues and other income	[2]	5,668		5,353		5,285
Gathering and Processing [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,848		4,089		2,956
Gathering and Processing [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Lease, Lease Income		287		347		365
Sales-type Lease, Revenue		62		0		0
Income (Loss) from Equity Method Investments		209		168		(1,090)
Other Operating Income		539	[3]	70		53
Adjusted EBITDA		1,957		1,879		1,723
Restructuring Charges		0		0		8
Capital Expenditure		528		224		441
Investments in unconsolidated affiliates		(120)		(118)		(125)
Total segment revenues and other income	[2]	5,945		4,674		2,284
Service [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,359		2,313		2,397
Service [Member] | Logistics and Storage [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		320		310		333
Service [Member] | Logistics and Storage [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,057		3,918		3,889
Service [Member] | Gathering and Processing [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,039		2,003		2,064
Service [Member] | Gathering and Processing [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,056		2,023		2,088
Product [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,219		1,590		636
Product [Member] | Logistics and Storage [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		19		14		51
Product [Member] | Gathering and Processing [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,792		2,066		868
Third Party | Logistics and Storage [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total segment revenues and other income		644		503		567
Third Party | Gathering and Processing [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total segment revenues and other income		$ 5,678		$ 4,463		$ 2,088
[1]The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively.[2]Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $644 million, $503 million and $567 million for the years ended December 31, 2022, 2021 and 2020, respectively. Third party revenues for the G&P segment were $5,678 million, $4,463 million and $2,088 million for the years ended December 31, 2022, 2021 and 2020, respectively.[3]Includes a $509 million non-cash gain on a lease reclassification for the year ended December 31, 2022. See Note 20 in the Consolidated Financial Statements for additional information.

Segment Information - Reconcili

Segment Information - Reconciliation Adjusted EBITDA to Net income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2020
Segment Reporting Information [Line Items]
Cost, Depreciation and Amortization		$ 1,230	$ 1,287		$ 1,377
Income (Loss) from Equity Method Investments		476	321	[1]	(936)	[1]
Distributions from unconsolidated affiliates		578	508		459
Asset Impairment Charges		0	(42)		(2,165)
Restructuring Charges		0	0		37
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		3,978	3,112		(687)
Other Income [Member]
Segment Reporting Information [Line Items]
Sales-type Lease, Selling Profit (Loss)		509	0		0
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA		5,775	5,560		5,211
Operating Segments | Logistics and Storage [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA		3,818	3,681		3,488
Cost, Depreciation and Amortization		515	546		633
Income (Loss) from Equity Method Investments		267	153		154
Restructuring Charges		0	0		29
Operating Segments | Gathering and Processing [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA		1,957	1,879		1,723
Cost, Depreciation and Amortization		715	741		744
Income (Loss) from Equity Method Investments		209	168		(1,090)
Restructuring Charges		0	0		8
Segment Reconciling Items
Segment Reporting Information [Line Items]
Cost, Depreciation and Amortization	[2]	1,230	1,287		1,377
Interest and Other Financial Costs		925	879		896
Income (Loss) from Equity Method Investments		476	321		(936)
Distributions from unconsolidated affiliates		652	537		499
Sales-type Lease, Selling Profit (Loss)		509	0		0
Asset Impairment Charges		0	(42)		(2,165)
Restructuring Charges		0	0		(37)
Adjusted EBITDA attributable to noncontrolling interests		38	39		37
Other Cost and Expense, Operating	[3]	$ (13)	$ (63)		$ (25)
[1]The 2021 and 2020 amounts include impairment of $6 million and $1,264 million, respectively.[2]Depreciation and amortization attributable to L&S was $515 million, $546 million and $633 million for the years ended December 31, 2022, 2021 and 2020, respectively. Depreciation and amortization attributable to G&P was $715 million, $741 million and $744 million for the years ended December 31, 2022, 2021 and 2020, respectively.[3]Includes unrealized derivative gain/(loss), non-cash equity-based compensation, provision for income taxes, and other miscellaneous items

Major Customers and Concentra_2

Major Customers and Concentration of Credit Risk (Details) - Marathon Petroleum Corporation [Member] - Revenues And Other Income] - Customer Concentration Risk		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Concentration Risk [Line Items]
Concentration risk, percentage	[1],[2]	47%	50%	55%
Logistics and Storage [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	[1],[2]	88%	90%	89%
Gathering and Processing [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	[1],[2]	4%	3%	4%
[1]The percent calculations exclude losses attributable to the impairment of equity method investments.[2]The percent calculations for the year ended December 31, 2022 exclude a $509 million non-cash gain on a lease reclassification.

Inventories (Summary of Invento

Inventories (Summary of Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
NGLs	$ 6	$ 12
Line fill	16	23
Spare parts, materials and supplies	126	107
Total inventories	$ 148	$ 142

Property, Plant and Equipment_2

Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 25,911	$ 26,546
Total property, plant and equipment	[1]	7,063	6,504
Less accumulated depreciation(1)		18,848	20,042
Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		12,416	12,371
Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		13,495	14,175
Pipelines And Related Assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		6,323	6,299
Refineries and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,710	1,650
Terminals and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,618	1,655
Barges and towing vessels [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,000	965
Land Building Office Equipment And Other [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		1,585	1,589
Land Building Office Equipment And Other [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		511	514
Gas Gathering And Transmission Equipment And Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		6,781	7,668
Processing, Fractionation And Storage Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		5,928	5,795
Construction-in-progress | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		180	213
Construction-in-progress | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross		$ 275	$ 198
Minimum | Pipelines And Related Assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		15 years
Minimum | Refineries and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		15 years
Minimum | Terminals and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		15 years
Minimum | Barges and towing vessels [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		15 years
Minimum | Land Building Office Equipment And Other [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		5 years
Minimum | Land Building Office Equipment And Other [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		5 years
Minimum | Gas Gathering And Transmission Equipment And Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		5 years
Minimum | Processing, Fractionation And Storage Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		10 years
Maximum | Pipelines And Related Assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		50 years
Maximum | Refineries and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		20 years
Maximum | Terminals and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		40 years
Maximum | Barges and towing vessels [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		20 years
Maximum | Land Building Office Equipment And Other [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		60 years
Maximum | Land Building Office Equipment And Other [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		40 years
Maximum | Gas Gathering And Transmission Equipment And Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		40 years
Maximum | Processing, Fractionation And Storage Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives		40 years
[1]Includes property, plant and equipment impairment charges recorded during the respective period, as discussed below.

Property Plant and Equipment (N

Property Plant and Equipment (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Accumulated depreciation	[1]	$ 7,063	$ 6,504
Interest costs capitalized		$ 9	14	$ 39
Impairment of Long-Lived Assets Held-for-use			$ 42
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]				Asset Impairment Charges
[1]Includes property, plant and equipment impairment charges recorded during the respective period, as discussed below.

Goodwill and Intangibles (Goodw

Goodwill and Intangibles (Goodwill) (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Nov. 30, 2022
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 0	$ 0
Number of reporting units	3
Goodwill	$ 7,645	7,657	$ 7,657
Impairment of Intangible Assets, Finite-lived			177
Total Number of Reporting Units	5
Crude Gathering [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount				1,000%
Gathering and Processing [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 0	0	1,814
Goodwill	$ 0	$ 0	$ 0
Measurement Input, Discount Rate [Member] | Goodwill | Income Approach Valuation Technique
Goodwill [Line Items]
Fair Value Inputs	10.10%
Measurement Input, Discount Rate [Member] | Goodwill | Income Approach Valuation Technique | Minimum
Goodwill [Line Items]
Fair Value Inputs			9.50%
Measurement Input, Discount Rate [Member] | Goodwill | Income Approach Valuation Technique | Maximum
Goodwill [Line Items]
Fair Value Inputs			11.50%

Goodwill and Intangibles (Recon

Goodwill and Intangibles (Reconciliation of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Gross goodwill	$ 10,786		$ 10,798
Goodwill, Impaired, Accumulated Impairment Loss	(3,141)		(3,141)
Goodwill, beginning balance	7,657	$ 7,657
Goodwill, Impairment Loss	0	0
Goodwill, Written off Related to Sale of Business Unit	(12)
Goodwill, ending balance	7,645	7,657	7,657
Logistics and Storage [Member]
Goodwill [Line Items]
Gross goodwill	7,645		7,657
Goodwill, Impaired, Accumulated Impairment Loss	0		0
Goodwill, beginning balance	7,657	7,657
Goodwill, Impairment Loss	0	0
Goodwill, Written off Related to Sale of Business Unit	(12)
Goodwill, ending balance	7,645	7,657	7,657
Gathering and Processing [Member]
Goodwill [Line Items]
Gross goodwill	3,141		3,141
Goodwill, Impaired, Accumulated Impairment Loss	(3,141)		(3,141)
Goodwill, beginning balance	0	0
Goodwill, Impairment Loss	0	0	(1,814)
Goodwill, Written off Related to Sale of Business Unit	0
Goodwill, ending balance	$ 0	$ 0	$ 0

Goodwill and Intangibles (Intan

Goodwill and Intangibles (Intangible Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross		$ 1,571	$ 1,571
Accumulated amortization	[1]	(866)	(740)
Intangible Assets, Net (Excluding Goodwill)		705	831
Impairment of Intangible Assets, Finite-lived				$ 177
Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration]				Asset Impairment Charges
Logistics and Storage [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets		36	36
Gross		283	283
Accumulated amortization	[1]	(153)	(117)
Intangible Assets, Net (Excluding Goodwill)		$ 130	166
Logistics and Storage [Member] | Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		6 years
Logistics and Storage [Member] | Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		8 years
Gathering and Processing [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets		$ 90	92
Gross		1,288	1,288
Accumulated amortization	[1]	(713)	(623)
Intangible Assets, Net (Excluding Goodwill)		$ 575	$ 665
Gathering and Processing [Member] | Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		6 years
Gathering and Processing [Member] | Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		25 years
[1]Amortization expense attributable to the L&S segment for both years ended December 31, 2022 and 2021 was $36 million. Amortization expense attributable to the G&P segment for the years ended December 31, 2022 and 2021 was $90 million and $92 million, respectively.

Goodwill and Intangibles (Futur

Goodwill and Intangibles (Future Amortization Expense) (Details) $ in Millions	Dec. 31, 2022 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2023	$ 127
2024	127
2025	113
2026	104
2027	76
2028 and thereafter	158
Total future intangibles amortization expenses	$ 705

Fair Value Measurements - Recur

Fair Value Measurements - Recurring (Significant Unobservable Inputs in Level 3 Valuation) (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.84
Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Embedded Derivative Renewal Term	5 years
Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Probability of Renewal	100%
Minimum | Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Embedded Derivative Liability, Measurement Input	0.68
Maximum | Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Embedded Derivative Liability, Measurement Input	1.62

Fair Value Measurements - Rec_2

Fair Value Measurements - Recurring (Changes in Level 3 Measurements) (Details) - Embedded Derivative Financial Instruments [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		$ (108)	$ (63)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	[1]	35	(59)
Settlements		12	14
Ending balance		(61)	(108)
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)		$ 33	$ (47)
[1]Gain/(loss) on derivatives embedded in commodity contracts are recorded in Purchased product costs on the Consolidated Statements of Income.

Fair Value Measurements - Repor

Fair Value Measurements - Reported (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Outstanding debt(1)	[1]	$ 18,095	$ 20,779
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Outstanding debt(1)	[1]	$ 19,905	$ 18,664
[1]Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in Current liabilities - related parties on the Consolidated Balance Sheets.

Derivative Financial Instrume_3

Derivative Financial Instruments (Embedded Derivatives in Commodity Contracts) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Derivative [Line Items]
Description of Embedded Derivative	MPLX has a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2027. The customer has the unilateral option to extend the agreement for one five-year term through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending option has been aggregated into a single compound embedded derivative.
Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Number of renewals	1
Term of counterparty option to renew gas purchase agreement	5 years
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ (61)	$ (108)	$ (63)
Fair Value, Recurring [Member] | Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative [Line Items]
Derivative Liability	$ 61	$ 108

Derivative Financial Instrume_4

Derivative Financial Instruments (Derivatives Balance Sheet Location) (Details) - Commodity Contract [Member] - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset		$ 0	$ 0
Derivative liability, fair value, gross liability	[1]	61	108
Not Designated as Hedging Instrument | Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset		0	0
Not Designated as Hedging Instrument | Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value, gross liability	[1]	10	15
Not Designated as Hedging Instrument | Other noncurrent assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset		0	0
Not Designated as Hedging Instrument | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value, gross liability	[1]	$ 51	$ 93
[1]Includes the embedded derivative in the commodity contract discussed above.

Derivative Financial Instrume_5

Derivative Financial Instruments (Derivatives Income Statement Location) (Details) - Purchased product costs - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Realized Gain (Loss), Net	$ (12)	$ (14)	$ (6)
Total derivative gain/(loss)	35	(59)	(9)
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ 47	$ (45)	$ (3)

Debt (Summary of Outstanding Bo

Debt (Summary of Outstanding Borrowings) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Sep. 15, 2022	Aug. 25, 2022	Dec. 31, 2021	Jan. 15, 2021
Debt Instrument [Line Items]
Finance Lease, Liability	[1]	$ 8			$ 9
Debt and capital lease obligations		20,108			18,909
Unamortized debt issuance costs		117			102
Unamortized discount		195			236
Debt, Current		988			499
Total long-term debt due after one year		18,808			18,072
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Outstanding balance					300
MPLX Revolving Credit Facility due July 2027
Debt Instrument [Line Items]
Outstanding balance		0
Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage				3.50%
Senior Notes | Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage			3.375%
Senior Notes | Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage						5.25%
MPLX LP | Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0			486
Debt Instrument, Maturity Date		Dec. 01, 2022
Interest rate, stated percentage		3.50%
MPLX LP | Senior Notes | Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0			500
Debt Instrument, Maturity Date		Mar. 15, 2023
Interest rate, stated percentage		3.375%
MPLX LP | Senior Notes | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 989			989
Debt Instrument, Maturity Date		Jul. 15, 2023
Interest rate, stated percentage		4.50%
MPLX LP | Senior Notes | Senior Notes Due December 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,149			1,149
Debt Instrument, Maturity Date		Dec. 01, 2024
Interest rate, stated percentage		4.875%
MPLX LP | Senior Notes | Senior Notes Due February 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 500			500
Debt Instrument, Maturity Date		Feb. 15, 2025
Interest rate, stated percentage		4%
MPLX LP | Senior Notes | Senior Notes Due June 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,189			1,189
Debt Instrument, Maturity Date		Jun. 01, 2025
Interest rate, stated percentage		4.875%
MPLX LP | Senior Notes | 4.125% senior notes due March 2027
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,250			1,250
Debt Instrument, Maturity Date		Mar. 01, 2027
Interest rate, stated percentage		4.125%
MPLX LP | Senior Notes | Senior Notes Due December 2027 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 732			732
Debt Instrument, Maturity Date		Dec. 01, 2027
Interest rate, stated percentage		4.25%
MPLX LP | Senior Notes | Senior Notes Due March 2028 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,250			1,250
Debt Instrument, Maturity Date		Mar. 15, 2028
Interest rate, stated percentage		4%
MPLX LP | Senior Notes | Senior Notes Due February 2029 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 750			750
Debt Instrument, Maturity Date		Feb. 15, 2029
Interest rate, stated percentage		4.80%
MPLX LP | Senior Notes | Senior Notes Due April 2038 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,750			1,750
Debt Instrument, Maturity Date		Apr. 15, 2038
Interest rate, stated percentage		4.50%
MPLX LP | Senior Notes | 5.200% senior notes due March 2047
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,000			1,000
Debt Instrument, Maturity Date		Mar. 01, 2047
Interest rate, stated percentage		5.20%
MPLX LP | Senior Notes | Senior Notes Due December 2047 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 487			487
Debt Instrument, Maturity Date		Dec. 01, 2047
Interest rate, stated percentage		5.20%
MPLX LP | Senior Notes | Senior Notes Due April 2048 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Debt Instrument, Maturity Date		Apr. 15, 2048
Interest rate, stated percentage		4.70%
MPLX LP | Senior Notes | Senior Notes Due February 2049 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Debt Instrument, Maturity Date		Feb. 15, 2049
Interest rate, stated percentage		5.50%
MPLX LP | Senior Notes | Senior Notes Due April 2058 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 500			500
Debt Instrument, Maturity Date		Apr. 15, 2058
Interest rate, stated percentage		4.90%
MPLX LP | Senior Notes | Senior Notes Due August 2030 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Debt Instrument, Maturity Date		Aug. 15, 2030
Interest rate, stated percentage		2.65%
MPLX LP | Senior Notes | Senior Notes Due March 2026 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Debt Instrument, Maturity Date		Mar. 01, 2026
Interest rate, stated percentage		1.75%
MarkWest | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross		$ 23			23
MarkWest | Senior Notes | Senior Notes Due July 2023 [Member] | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		4.50%
MarkWest | Senior Notes | Senior Notes Due June 2025 [Member] | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		4.875%
ANDX LP [Member] | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross		$ 31			$ 45
ANDX LP [Member] | Senior Notes | Senior Notes Due December 2022 [Member] | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage		3.50%
ANDX LP [Member] | Senior Notes | Senior Notes Due January 2025 [Member] | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage		5.20%
ANDX LP [Member] | Senior Notes | Senior Notes Due December 2027 [Member] | Minimum
Debt Instrument [Line Items]
Debt Instrument, Maturity Date		Dec. 01, 2027
ANDX LP [Member] | Senior Notes | Senior Notes Due December 2047 [Member] | Maximum
Debt Instrument [Line Items]
Debt Instrument, Maturity Date		Dec. 01, 2047
[1]See Note 20 for lease information.

Debt (Summary of Outstanding _2

Debt (Summary of Outstanding Borrowings Interest Rates and Table Due Dates) (Details) - Senior Notes - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Sep. 15, 2022	Aug. 25, 2022	Aug. 11, 2022	Mar. 14, 2022	Dec. 31, 2021	Jan. 15, 2021
4.000% senior notes due February 2025
Debt Instrument [Line Items]
Interest rate, stated percentage			3.50%
4.875% senior notes due June 2025
Debt Instrument [Line Items]
Interest rate, stated percentage		3.375%
Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage							5.25%
Senior Note Due September 2032
Debt Instrument [Line Items]
Interest rate, stated percentage				4.95%
Senior Note Due March 2052 [Domain]
Debt Instrument [Line Items]
Interest rate, stated percentage					4.95%
MPLX LP | 4.000% senior notes due February 2025
Debt Instrument [Line Items]
Interest rate, stated percentage	3.50%
Debt Instrument, Maturity Date	Dec. 01, 2022
Long-term debt, gross	$ 0					$ 486
MPLX LP | 4.875% senior notes due June 2025
Debt Instrument [Line Items]
Interest rate, stated percentage	3.375%
Debt Instrument, Maturity Date	Mar. 15, 2023
Long-term debt, gross	$ 0					500
MPLX LP | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Debt Instrument, Maturity Date	Jul. 15, 2023
Long-term debt, gross	$ 989					989
MPLX LP | Senior Notes Due March 2028 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4%
Debt Instrument, Maturity Date	Mar. 15, 2028
Long-term debt, gross	$ 1,250					1,250
MPLX LP | Senior Notes Due February 2029 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.80%
Debt Instrument, Maturity Date	Feb. 15, 2029
Long-term debt, gross	$ 750					750
MPLX LP | Senior Notes Due April 2038 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Debt Instrument, Maturity Date	Apr. 15, 2038
Long-term debt, gross	$ 1,750					1,750
MPLX LP | 5.200% senior notes due March 2047
Debt Instrument [Line Items]
Interest rate, stated percentage	5.20%
Debt Instrument, Maturity Date	Mar. 01, 2047
Long-term debt, gross	$ 1,000					1,000
MPLX LP | Senior Notes Due April 2048 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.70%
Debt Instrument, Maturity Date	Apr. 15, 2048
Long-term debt, gross	$ 1,500					1,500
MPLX LP | Senior Notes Due November 2049 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	5.50%
Debt Instrument, Maturity Date	Feb. 15, 2049
Long-term debt, gross	$ 1,500					1,500
MPLX LP | Senior Notes Due April 2058 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.90%
Debt Instrument, Maturity Date	Apr. 15, 2058
Long-term debt, gross	$ 500					500
MPLX LP | Senior Notes Due December 2024 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.875%
Debt Instrument, Maturity Date	Dec. 01, 2024
Long-term debt, gross	$ 1,149					1,149
MPLX LP | Senior Notes Due February 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4%
Debt Instrument, Maturity Date	Feb. 15, 2025
Long-term debt, gross	$ 500					500
MPLX LP | Senior Notes Due June 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.875%
Debt Instrument, Maturity Date	Jun. 01, 2025
Long-term debt, gross	$ 1,189					1,189
MPLX LP | Senior Notes Due March 2027 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.125%
Debt Instrument, Maturity Date	Mar. 01, 2027
Long-term debt, gross	$ 1,250					1,250
MPLX LP | Senior Notes Due December 2027 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.25%
Debt Instrument, Maturity Date	Dec. 01, 2027
Long-term debt, gross	$ 732					732
MPLX LP | Senior Notes Due December 2047 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	5.20%
Debt Instrument, Maturity Date	Dec. 01, 2047
Long-term debt, gross	$ 487					487
MPLX LP | Senior Notes Due March 2026 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	1.75%
Debt Instrument, Maturity Date	Mar. 01, 2026
Long-term debt, gross	$ 1,500					1,500
MPLX LP | Senior Notes Due August 2030 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	2.65%
Debt Instrument, Maturity Date	Aug. 15, 2030
Long-term debt, gross	$ 1,500					1,500
MPLX LP | Senior Note Due September 2032
Debt Instrument [Line Items]
Interest rate, stated percentage	4.95%
Debt Instrument, Maturity Date	Sep. 01, 2032
Long-term debt, gross	$ 1,000					0
MPLX LP | Senior Note Due March 2052 [Domain]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.95%
Debt Instrument, Maturity Date	Mar. 14, 2052
Long-term debt, gross	$ 1,500					0
MarkWest
Debt Instrument [Line Items]
Long-term debt, gross	$ 23					23
MarkWest | Senior Notes Due July 2023 [Member] | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
MarkWest | Senior Notes Due June 2025 [Member] | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.875%
ANDX LP [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 31					$ 45
ANDX LP [Member] | 4.000% senior notes due February 2025 | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	3.50%
ANDX LP [Member] | Senior Notes Due January 2025 [Member] | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	5.20%
ANDX LP [Member] | Senior Notes Due December 2027 [Member] | Minimum
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Dec. 01, 2027
ANDX LP [Member] | Senior Notes Due December 2047 [Member] | Maximum
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Dec. 01, 2047

Debt (Schedule of Debt Payments

Debt (Schedule of Debt Payments) (Detail) $ in Millions	Dec. 31, 2022 USD ($)
Debt Disclosure [Abstract]
2023	$ 1,002
2024	1,152
2025	1,701
2026	1,501
2027	$ 2,001

Debt (Credit Agreements) (Detai

Debt (Credit Agreements) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 3,500
Proceeds from long-term lines of credit		$ 4,175
Debt, Weighted Average Interest Rate		1.34%
Repayments of long-term lines of credit		$ 4,050
Letters of credit outstanding, amount		0.2
Remaining borrowing capacity		$ 3,200
Remaining borrowing capacity, percentage		91%
Long-term Line of Credit		$ 300
MPLX Revolving Credit Facility due July 2027
Debt Instrument [Line Items]
Maximum borrowing capacity	2,000
Proceeds from long-term lines of credit	$ 900
Debt, Weighted Average Interest Rate	1.45%
Number of renewals	2
Debt Instrument, Renewal Term	1 year
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
Number of prior quarterly reporting periods used in determining compliance with covenant of ratio of consolidated net debt to consolidated EBITDA	4
Covenant of ratio of consolidated net debt to consolidated EBITDA (in ratio)	5
Covenant of ratio of consolidated net debt to consolidated EBITDA following certain acquisitions (in ratio)	5.5
Repayments of long-term lines of credit	$ 1,200
Letters of credit outstanding, amount	0.2
Remaining borrowing capacity	$ 2,000
Remaining borrowing capacity, percentage	100%
Long-term Line of Credit	$ 0
Debt Instrument, Second Renewal Term	1 year
Expiration date	Jul. 07, 2027
MPLX Revolving Credit Facility due July 2027 | Maximum
Debt Instrument [Line Items]
Additional borrowing capacity	$ 1,000
MPLX Revolving Credit Facility due July 2027 | Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	150
Senior Notes | ANDX LP [Member]
Debt Instrument [Line Items]
Long-term debt, outstanding	$ 31	$ 45

Debt (Senior Notes) (Details)

Debt (Senior Notes) (Details) - USD ($) $ in Millions		12 Months Ended
	Feb. 15, 2023	Dec. 31, 2022	Dec. 31, 2021	Feb. 09, 2023	Sep. 15, 2022	Aug. 25, 2022	Aug. 11, 2022	Mar. 14, 2022	Jan. 15, 2021
Subsequent Event | Series B Preferred Stock [Member]
Debt Instrument [Line Items]
Payments for Repurchase of Preferred Stock and Preference Stock	$ 600
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 3,500
Outstanding balance			$ 300
Senior Notes | Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage					3.375%
Percent of par					100%
Debt Instrument, Face Amount					$ 500
Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage						3.50%
Percent of par						100.101%
Debt Instrument, Face Amount						$ 500
Senior Notes | Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage									5.25%
Percent of par									102.625%
Gain (Loss) on Extinguishment of Debt			8
Write off of Deferred Debt Issuance Cost			12
Gain (Loss) on Extinguishment of Debt, before Write off of Debt Issuance Cost			20
Debt Instrument, Face Amount									$ 750
Senior Notes | Senior Note Due March 2052 [Domain]
Debt Instrument [Line Items]
Interest rate, stated percentage								4.95%
Percent of par								98.982%
Debt Instrument, Face Amount								$ 1,500
Senior Notes | Senior Note Due September 2032
Debt Instrument [Line Items]
Interest rate, stated percentage							4.95%
Percent of par							99.433%
Debt Instrument, Face Amount							$ 1,000
Senior Notes | Senior Note Due March 2033 | Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage				5%
Percent of par				99.17%
Debt Instrument, Face Amount				$ 1,100
Senior Notes | Senior Notes Due July 2023 [Member] | Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage				4.50%
Debt Instrument, Face Amount				$ 1,000
Senior Notes | Senior Note Due March 2053 | Subsequent Event
Debt Instrument [Line Items]
Interest rate, stated percentage				5.65%
Percent of par				99.536%
Debt Instrument, Face Amount				$ 500
Senior Notes | Senior Notes Due March 2033 and March 2053 | Subsequent Event
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 1,600
MPLX LP | Senior Notes | Senior Notes Due February 2029 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 750	750
Interest rate, stated percentage		4.80%
Debt Instrument, Maturity Date		Feb. 15, 2029
MPLX LP | Senior Notes | Senior Notes Due February 2049 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500	1,500
Interest rate, stated percentage		5.50%
Debt Instrument, Maturity Date		Feb. 15, 2049
MPLX LP | Senior Notes | Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0	500
Interest rate, stated percentage		3.375%
Debt Instrument, Maturity Date		Mar. 15, 2023
MPLX LP | Senior Notes | 4.125% senior notes due March 2027
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,250	1,250
Interest rate, stated percentage		4.125%
Debt Instrument, Maturity Date		Mar. 01, 2027
MPLX LP | Senior Notes | 5.200% senior notes due March 2047
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,000	1,000
Interest rate, stated percentage		5.20%
Debt Instrument, Maturity Date		Mar. 01, 2047
MPLX LP | Senior Notes | Senior Notes Due March 2028 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,250	1,250
Interest rate, stated percentage		4%
Debt Instrument, Maturity Date		Mar. 15, 2028
MPLX LP | Senior Notes | Senior Notes Due April 2038 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,750	1,750
Interest rate, stated percentage		4.50%
Debt Instrument, Maturity Date		Apr. 15, 2038
MPLX LP | Senior Notes | Senior Notes Due April 2048 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500	1,500
Interest rate, stated percentage		4.70%
Debt Instrument, Maturity Date		Apr. 15, 2048
MPLX LP | Senior Notes | Senior Notes Due April 2058 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 500	500
Interest rate, stated percentage		4.90%
Debt Instrument, Maturity Date		Apr. 15, 2058
MPLX LP | Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0	486
Interest rate, stated percentage		3.50%
Debt Instrument, Maturity Date		Dec. 01, 2022
MPLX LP | Senior Notes | Senior Notes Due December 2027 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 732	732
Interest rate, stated percentage		4.25%
Debt Instrument, Maturity Date		Dec. 01, 2027
MPLX LP | Senior Notes | Senior Notes Due December 2047 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 487	487
Interest rate, stated percentage		5.20%
Debt Instrument, Maturity Date		Dec. 01, 2047
MPLX LP | Senior Notes | Senior Notes Due March 2026 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500	1,500
Interest rate, stated percentage		1.75%
Debt Instrument, Maturity Date		Mar. 01, 2026
MPLX LP | Senior Notes | Senior Notes Due August 2030 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500	1,500
Interest rate, stated percentage		2.65%
Debt Instrument, Maturity Date		Aug. 15, 2030
MPLX LP | Senior Notes | Senior Note Due March 2052 [Domain]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500	0
Interest rate, stated percentage		4.95%
Debt Instrument, Maturity Date		Mar. 14, 2052
MPLX LP | Senior Notes | Senior Note Due September 2032
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,000	0
Interest rate, stated percentage		4.95%
Debt Instrument, Maturity Date		Sep. 01, 2032
MPLX LP | Senior Notes | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 989	989
Interest rate, stated percentage		4.50%
Debt Instrument, Maturity Date		Jul. 15, 2023
ANDX LP [Member] | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross		$ 31	45
ANDX LP [Member] | Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 14
ANDX LP [Member] | Senior Notes | Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount									$ 42
MarkWest | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross		$ 23	$ 23
Minimum | ANDX LP [Member] | Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		3.50%
Minimum | ANDX LP [Member] | Senior Notes | Senior Notes Due December 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date		Dec. 01, 2027
Minimum | MarkWest | Senior Notes | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		4.50%
Maximum | ANDX LP [Member] | Senior Notes | Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		5.20%
Maximum | ANDX LP [Member] | Senior Notes | Senior Notes Due December 2047 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date		Dec. 01, 2047

Revenue Disaggregation of Reven

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer, Other	[1]	$ 2,689	$ 2,006	$ 673
Revenues		11,613	10,027	7,569
Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		8,924	8,021	6,896
Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,359	2,313	2,397
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		3,754	3,628	3,580
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		394	345	155
Product [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,219	1,590	636
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		198	145	128
Product [Member] | Third Party
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,219	1,590	636
Logistics and Storage [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,076	3,932	3,940
Logistics and Storage [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[2]	5,668	5,353	5,285
Logistics and Storage [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		320	310	333
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		3,737	3,608	3,556
Logistics and Storage [Member] | Service [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,057	3,918	3,889
Logistics and Storage [Member] | Service, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0
Logistics and Storage [Member] | Product [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		13	10	12
Logistics and Storage [Member] | Product [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		19	14	51
Logistics and Storage [Member] | Product [Member] | Third Party
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		6	4	39
Gathering and Processing [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,848	4,089	2,956
Gathering and Processing [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[2]	5,945	4,674	2,284
Gathering and Processing [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,039	2,003	2,064
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		17	20	24
Gathering and Processing [Member] | Service [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,056	2,023	2,088
Gathering and Processing [Member] | Service, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		394	345	155
Gathering and Processing [Member] | Product [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		185	135	116
Gathering and Processing [Member] | Product [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,792	2,066	868
Gathering and Processing [Member] | Product [Member] | Third Party
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 2,213	$ 1,586	$ 597
[1]Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income/(loss) 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 $644 million, $503 million and $567 million for the years ended December 31, 2022, 2021 and 2020, respectively. Third party revenues for the G&P segment were $5,678 million, $4,463 million and $2,088 million for the years ended December 31, 2022, 2021 and 2020, respectively.

Revenue Contract Balance Rollfo

Revenue Contract Balance Rollforward (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Beginning Balance Deferred Revenue, Noncurrent		$ 383
Ending Balance Deferred Revenue, Noncurrent		219	$ 383
Contract with Customer, Liability, Change in Timeframe, Performance Obligation Satisfied, Revenue Recognized		0	0
Accounting Standards Update 2014-09 [Member]
Beginning Balance Contract with Customer, Asset, Gross		25	40
Contract with Customer, Asset Increase (Decrease)		(4)	(15)
Contract with Customer, Asset, Reclassified to Receivable	[1]	0	0
Ending Balance Contract with Customer, Asset, Gross		21	25
Contract with Customer, Non Current Asset Reclassified to Receivable	[1]	0	0
Contract with Customer, Asset Increase (Decrease), Noncurrent		(1)	0
Contract with Customer, Asset, before Allowance for Credit Loss, Noncurrent		1	2	$ 2
Beginning Balance Deferred Revenue, Current		56	37
Deferred Revenue, Period Increase (Decrease)		41	56
Deferred Revenue, Revenue Recognized	[1]	(40)	(37)
Ending Balance Deferred Revenue, Current		57	56
Beginning Balance Deferred revenue - related parties		60	91
Deferred Revenue - Related Party, Period Increase (Decrease)		109	75
Deferred Revenue - Related Parties, Revenue Recognized	[1]	(106)	(106)
Ending Balance Deferred Revenue, Current, Related Parties		63	60
Beginning Balance Deferred Revenue, Noncurrent		135	119
Deferred Revenue, Noncurrent, Period Increase (Decrease)		81	16
Deferred Revenue, Noncurrent, Revenue Recognized	[1]	0	0
Ending Balance Deferred Revenue, Noncurrent		216	135
Beginning Balance Deferred Revenue, Noncurrent, Related Parties		31	48
Deferred Revenue, Noncurrent, Related Party, Period Increase (Decrease)		(6)	(17)
Deferred Revenue, Noncurrent, Related Parties, Revenue Recognized	[1]	0	0
Ending Balance Deferred Revenue, Noncurrent, Related Parties		25	31
Contract Liability, Noncurrent, Revenue Recognized	[1]	0	0
Contract Liability, Noncurrent, Period Increase (Decrease) [Line Items]		(3)	(1)
Contract with Customer, Liability, Noncurrent		$ 2	$ 5	$ 6
[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	Dec. 31, 2022 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Liability	$ 360
Revenue, Remaining Performance Obligation, Amount	8,729	[1],[2],[3]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,844
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,717
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,634
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	3 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,471
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	4 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,330
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	5 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 733
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2043-10-31
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	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	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Interest paid (net of amounts capitalized)	$ 813	$ 812	$ 821
Income taxes paid	3	4	2
Operating Lease, Payments	73	79	87
Finance Lease, Interest Expense	0	0	1
Finance Lease, Principal Payments	2	2	9
Non-cash investing and financing activities:
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	(1)	1	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	78	20	17
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	1	0	1
Fair Value of Units Redeemed	$ 0	$ 0	$ 340

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	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Increase/(decrease) in capital accruals	$ 47	$ 11	$ (244)
Capital Expenditure	853	540	939
Payments to Acquire Property, Plant, and Equipment	$ 806	$ 529	$ 1,183

Leases Lessee Disclosures (Deta

Leases Lessee Disclosures (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, to be Paid, Year One		$ 2
Finance Lease, Liability, to be Paid, Year Two		2
Finance Lease, Liability, to be Paid, Year Three		1
Finance Lease, Liability, to be Paid, Year Four		1
Finance Lease, Liability, to be Paid, Year Five		1
Finance Lease, Liability, to be Paid, after Year Five		7
Finance Lease, Liability, Payment, Due		14
Finance Lease, Liability, Undiscounted Excess Amount		6
Finance Lease, Liability	[1]	$ 8	$ 9
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Debt, Current	Debt, Current
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Long-term Debt and Lease Obligation	Long-term Debt and Lease Obligation
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]		Debt, Current, Long-term Debt and Lease Obligation	Long-term Debt and Lease Obligation, Debt, Current
Third Party
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		$ 61	$ 71	$ 78
Finance Lease, Right-of-Use Asset, Amortization		1	2	3
Finance Lease, Interest Expense		1	1	1
Finance Lease Cost		2	3	4
Variable Lease, Cost		16	15	10
Short-term Lease, Cost		45	31	52
Lease, Cost		124	120	144
Lessee, Operating Lease, Liability, to be Paid, Year One		56
Lessee, Operating Lease, Liability, to be Paid, Year Two		46
Lessee, Operating Lease, Liability, to be Paid, Year Three		34
Lessee, Operating Lease, Liability, to be Paid, Year Four		30
Lessee, Operating Lease, Liability, to be Paid, Year Five		29
Lessee, Operating Lease, Liability, to be Paid, after Year Five		135
Lessee, Operating Lease, Liability, to be Paid		330
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		54
Operating Lease, Liability		276	264
Finance Lease, Liability		8	9
Operating Lease, Right-of-Use Asset		283	268
Operating Lease, Liability, Current		46	59
Operating Lease, Liability, Noncurrent		$ 230	$ 205
Operating Lease, Weighted Average Remaining Lease Term		9 years 2 months 12 days	8 years 3 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent		4.10%	4.10%
Finance Lease, Right-of-Use Asset, before Accumulated Amortization		$ 11	$ 11
Finance Lease, Right-of-Use Asset, Accumulated Amortization		4	4
Finance Lease, Right-of-Use Asset, after Accumulated Amortization		7	7
Other current liabilities		1	2
Long-term debt		$ 7	$ 7
Finance Lease, Weighted Average Remaining Lease Term		18 years 4 months 24 days	19 years 4 months 24 days
Finance Lease, Weighted Average Discount Rate, Percent		6%	6%
Marathon Petroleum Corporation [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		$ 15	$ 15	14
Finance Lease, Right-of-Use Asset, Amortization		0	0	0
Finance Lease, Interest Expense		0	0	0
Finance Lease Cost		0	0	0
Variable Lease, Cost		2	0	1
Short-term Lease, Cost		0	0	0
Lease, Cost		17	15	$ 15
Lessee, Operating Lease, Liability, to be Paid, Year One		15
Lessee, Operating Lease, Liability, to be Paid, Year Two		15
Lessee, Operating Lease, Liability, to be Paid, Year Three		14
Lessee, Operating Lease, Liability, to be Paid, Year Four		14
Lessee, Operating Lease, Liability, to be Paid, Year Five		14
Lessee, Operating Lease, Liability, to be Paid, after Year Five		561
Lessee, Operating Lease, Liability, to be Paid		633
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		404
Operating Lease, Liability		229	229
Operating Lease, Right-of-Use Asset		228	229
Operating Lease, Liability, Current		1	1
Operating Lease, Liability, Noncurrent, Related Party		$ 228	$ 228
Operating Lease, Weighted Average Remaining Lease Term		44 years 2 months 12 days	45 years 2 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent		5.80%	5.80%
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Remaining Lease Term		96 years
Lessee, Operating Lease, Renewal Term		50 years
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Remaining Lease Term		1 year
Lessee, Operating Lease, Renewal Term		1 year
[1]See Note 20 for lease information.

Leases Lessor Disclosures (Deta

Leases Lessor Disclosures (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020	Aug. 01, 2022	Jul. 31, 2022	Apr. 30, 2021	Mar. 31, 2020
Lessor, Lease, Description [Line Items]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		$ 658
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		645
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		635
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		596
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		485
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		1,184
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		4,203
Lessor, Operating Lease, Payment to be Received, Year One		724
Operating Lease, Lease Income		327		$ 376	$ 398
Lessor, Operating Lease, Payment to be Received, Year Two		664
Lessor, Operating Lease, Payment to be Received, Year Three		610
Lessor, Operating Lease, Payment to be Received, Year Four		483
Lessor, Operating Lease, Payment to be Received, Year Five		346
Lessor, Operating Lease, Payment to be Received, after Year Five		170
Lessor, Operating Lease, Payments to be Received		2,997
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		2,268
Sales-type Lease, Lease Receivable	[1]	1,935
Sales-type Lease, Unguaranteed Residual Asset	[2]	153
Accumulated depreciation		1,880		2,042
Property, Plant and Equipment, Net		2,697		3,510
Property Subject to or Available for Operating Lease, Gross		4,577		5,552
Operating Lease, Lease Income, Related Party		763		743	952
Sales-type Lease, Revenue		62		0	0
Deferred Revenue, Noncurrent		219		383
Partners' Capital Account, Contributions		82		160	261
Net Investment in Lease, Current	[3]	209
Net Investment in Lease, Noncurrent	[2]	1,726
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		2,088
Capital Expenditure		853		540	939
Reclassification, Other
Lessor, Lease, Description [Line Items]
Property, Plant and Equipment, Transfers and Changes		72
Pipelines And Related Assets [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		670		953
Refineries and related assets [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		1,310		1,146
Terminals and related assets [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		1,241		1,290
Barges and towing vessels [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		126		129
Gas Gathering And Transmission Equipment And Facilities [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		94		991
Processing, Fractionation And Storage Facilities [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		973		867
Land Building Office Equipment And Other [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		163		176
Third Party
Lessor, Lease, Description [Line Items]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		169
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		156
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		146
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		137
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		128
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		970
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		1,706
Lessor, Operating Lease, Payment to be Received, Year One		97
Sales-type Lease, Selling Profit (Loss)		509	[4]	0	0
Sales-type Lease, Interest Income		46		0	0
Sales-type Lease, Variable Lease Income		16		0	0
Lessor, Operating Lease, Payment to be Received, Year Two		95
Lessor, Operating Lease, Payment to be Received, Year Three		64
Lessor, Operating Lease, Payment to be Received, Year Four		37
Lessor, Operating Lease, Payment to be Received, Year Five		16
Lessor, Operating Lease, Payment to be Received, after Year Five		21
Lessor, Operating Lease, Payments to be Received		330
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		765
Sales-type Lease, Lease Receivable		941	[1]	0	0		$ 914
Sales-type Lease, Unguaranteed Residual Asset		66	[2]	0	0		63
Sales Type Lease Derecognition Properties And Equipment Net				0	0		745
Sales-type Lease, Revenue		62		0	0
Deferred Revenue, Noncurrent				0	0		$ 277
Net Investment in Lease, Current	[3]	98
Net Investment in Lease, Noncurrent	[2]	843
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		1,007
Marathon Petroleum Corporation [Member]
Lessor, Lease, Description [Line Items]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		489
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		489
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		489
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		459
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		357
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		214
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		2,497
Lessor, Operating Lease, Payment to be Received, Year One		627
Sales-type Lease, Interest Income		447		431	151
Sales-type Lease, Variable Lease Income		18		4	1
Lessor, Operating Lease, Payment to be Received, Year Two		569
Lessor, Operating Lease, Payment to be Received, Year Three		546
Lessor, Operating Lease, Payment to be Received, Year Four		446
Lessor, Operating Lease, Payment to be Received, Year Five		330
Lessor, Operating Lease, Payment to be Received, after Year Five		149
Lessor, Operating Lease, Payments to be Received		2,667
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		1,503
Sales-type Lease, Lease Receivable	[1]	994
Sales-type Lease, Unguaranteed Residual Asset	[2]	87
Sales-type Lease, Revenue		465		435	152
Net Investment in Lease, Current	[3]	111
Net Investment in Lease, Noncurrent	[2]	883
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		1,081
Marathon Petroleum Corporation [Member] | Limited Partners Common Units
Lessor, Lease, Description [Line Items]
Partners' Capital Account, Contributions		82		160	261
Marathon Petroleum Corporation [Member] | Gain (loss) on sales-type lease | Limited Partners Common Units
Lessor, Lease, Description [Line Items]
Partners' Capital Account, Contributions	[5]	43		112	$ 209
Affiliated Entity
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable						$ 87		$ 519	$ 370
Sales-type Lease, Unguaranteed Residual Asset		87		47		6		14	10
Sales Type Lease Derecognition Properties And Equipment Net						50		421	171
Deferred Revenue, Noncurrent						$ 0		$ 0	$ 0
Net Investment in Lease, Current		111		82
Net Investment in Lease, Noncurrent		$ 883		$ 854
Maximum
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years
Maximum | Lease Agreements, Lessor [Member]
Lessor, Lease, Description [Line Items]
Term Of Agreements		10 years
Minimum
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		1 year
Minimum | Lease Agreements, Lessor [Member]
Lessor, Lease, Description [Line Items]
Term Of Agreements		1 year
[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_2

Commitments and Contingencies (Detail) - USD ($) $ in Millions		1 Months Ended
	Dec. 15, 2020	Jul. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Commitments And Contingencies [Line Items]
Contractual commitments to acquire property, plant and equipment			$ 165
Loss Contingency, Damages Sought, Value		$ 187
Loss Contingency, Damages Paid, Value	$ 4
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]			Deferred Credits and Other Liabilities, Noncurrent, Other Liabilities, Current	Deferred Credits and Other Liabilities, Noncurrent, Other Liabilities, Current
Accrual for environmental loss contingencies			$ 17	$ 23
Indirect Ownership Interest | Bakken Pipeline System | Logistics and Storage [Member]
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage			9.19%
Financial Guarantee | Bakken Pipeline System | Guarantee of Indebtedness of Others
Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted			$ 170

Commitments and Contingencies_3

Commitments and Contingencies (Minimum Future Payments) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Transportation And Terminalling Agreements
Other Commitments [Line Items]
2023	$ 162
2024	152
2025	128
2026	118
2027	114
2028 and thereafter	204
Total	$ 878
Minimum Committed Volume Contracts [Member] | Minimum
Other Commitments [Line Items]
Term Of Agreements	1 year
Minimum Committed Volume Contracts [Member] | Maximum
Other Commitments [Line Items]
Term Of Agreements	9 years

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - USD ($) $ / shares in Units, $ in Millions	Feb. 15, 2023	Feb. 09, 2023
Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Stock, Redemption Price Per Share	$ 1,000
Payments for Repurchase of Preferred Stock and Preference Stock	$ 600
Senior Note Due March 2033 | Senior Notes
Subsequent Event [Line Items]
Interest rate, stated percentage		5%
Debt Instrument, Face Amount		$ 1,100
Percent of par		99.17%
Senior Note Due March 2053 | Senior Notes
Subsequent Event [Line Items]
Interest rate, stated percentage		5.65%
Debt Instrument, Face Amount		$ 500
Percent of par		99.536%
Senior Notes Due July 2023 [Member] | Senior Notes
Subsequent Event [Line Items]
Interest rate, stated percentage		4.50%
Debt Instrument, Face Amount		$ 1,000
Senior Notes Due March 2033 and March 2053 | Senior Notes
Subsequent Event [Line Items]
Debt Instrument, Face Amount		$ 1,600