MPLX (MPLX) 10-K 28 Feb 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2023	Feb. 23, 2024	Jun. 30, 2023
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	422-2121
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			$ 12
Entity Common Stock, Shares Outstanding		1,010,717,254
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001552000
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2023
Document Information [Line Items]
Document Transition Report	false
Document Financial Statement Error Correction [Flag]	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
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, 2023	Dec. 31, 2022		Dec. 31, 2021
Revenues and other income:
Sales-type Lease, Revenue	$ 136	$ 62		$ 0
Sales-type lease revenue, related parties	500	465		435
Income from equity method investments	600	476		321
Total revenues and other income	11,281	11,613		10,027
Costs and expenses:
Purchases - related parties	1,544	1,413		1,219
Depreciation and amortization	1,213	1,230		1,287
Impairment expense	0	0		42
General and administrative expenses	379	335		353
Other taxes	131	115		120
Total costs and expenses	6,381	6,702		6,035
Income from operations	4,900	4,911		3,992
Interest expense, net of amounts capitalized	897	843		785
Interest Expense, Other	26	77		86
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	3,977	3,986		3,113
Income Tax Expense (Benefit)	11	8		1
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total	3,966	3,978		3,112
Net Income (Loss) Attributable to Noncontrolling Interest	38	34		35
Net Income (Loss) Attributable to Parent, Total	3,928	3,944	[1]	3,077
Net Income (Loss) Allocated to Limited Partners	$ 3,829	$ 3,815		$ 2,936
Net Income Attributable To Parent Company Per Limited Partner Unit Basic And Diluted [Abstract]
Common - basic (in USD per unit)	$ 3.80	$ 3.75		$ 2.86
Common - diluted (in USD per unit)	$ 3.80	$ 3.75		$ 2.86
Limited Partners' Capital Account [Abstract]
Common - basic (in units)	1,001	1,010		1,027
Common - diluted (in units)	1,002	1,010		1,027
Nonrelated Party
Revenues and other income:
Rental Income	$ 243	$ 327		$ 376
Sales-type Lease, Revenue	136	62		0
Other Income	126	485		21
Costs and expenses:
Rental cost of sales	82	123		136
Related Party
Revenues and other income:
Rental Income	822	763		743
Sales-type lease revenue, related parties	500	465		435
Other Income	121	111		110
Costs and expenses:
Rental cost of sales	33	54		109
Related-party interest and other financial costs	0	5		8
Service [Member]
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	3,985	3,754		3,628
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties	2,539	2,359		2,313
Product [Member]
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties	250	198		145
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties	1,665	2,219		1,590
Oil and Gas, Refining and Marketing [Member]
Costs and expenses:
Cost of Goods and Services Sold	1,401	1,369		1,184
Natural Gas, Midstream [Member]
Costs and expenses:
Cost of Goods and Services Sold	1,598	2,063		1,585
Service, Other [Member]
Revenues and other income:
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties	294	394		345
Series A Preferred Stock [Member]
Costs and expenses:
Net Income (Loss) Attributable to Parent, Total	110	112	[1]	100
Preferred Stock Dividends, Income Statement Impact	94	88		100
Series B Preferred Stock [Member]
Costs and expenses:
Net Income (Loss) Attributable to Parent, Total	5	41	[1]	41
Preferred Stock Dividends, Income Statement Impact	$ 5	$ 41		$ 41
[1]The year ended December 31, 2022 includes a $509 million gain on a lease reclassification. See Note 20 for additional information.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income Statement - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 3,966	$ 3,978	$ 3,112
Other comprehensive income/(loss), net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	4	9	(2)
Comprehensive income	3,970	3,987	3,110
Less comprehensive income attributable to:
Noncontrolling interests	38	34	35
Comprehensive income attributable to MPLX LP	$ 3,932	$ 3,953	$ 3,075

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets, Current [Abstract]
Cash and cash equivalents	$ 1,048	$ 238
Receivables, net	823	737
Inventories	159	148
Other current assets	30	53
Total current assets	2,808	1,905
Equity method investments	3,743	4,095
Property, plant and equipment, net	19,264	18,848
Intangibles, net	654	705
Goodwill	7,645	7,645
Right of use assets, net	264	283
Other noncurrent assets	990	959
Total assets	36,529	35,665
Liabilities, Current [Abstract]
Accounts payable	153	224
Accrued liabilities	300	269
Accrued property, plant and equipment	216	128
Long-term debt due within one year	1,135	988
Accrued interest payable	242	237
Total current liabilities	2,624	2,401
Long-term deferred revenue	347	219
Long-term debt	19,296	18,808
Deferred income taxes	16	13
Long-term operating lease liabilities	211	230
Other long-term liabilities	126	142
Total liabilities	22,945	22,151
Commitments and contingencies (see Note 21)
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests	895	968
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred Units, Preferred Partners' Capital Accounts	0	611
Accumulated other comprehensive loss	(4)	(8)
Total MPLX LP partners’ capital	12,454	12,309
Noncontrolling interests	235	237
Total equity	12,689	12,546
Total liabilities, preferred units and equity	36,529	35,665
Related Party
Assets, Current [Abstract]
Receivables, net	587	610
Due from Related Parties, Current	748	729
Other current assets	7	3
Right of use assets, net	227	228
Noncurrent assets - related parties	1,161	1,225
Liabilities, Current [Abstract]
Operating lease liabilities	1	1
Other Liabilities, Current	360	343
Long-term deferred revenue	99	110
Long-term liabilities - related parties	325	338
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited Partners' Capital Account	3,758	3,293
Nonrelated Party
Assets, Current [Abstract]
Right of use assets, net	264	283
Liabilities, Current [Abstract]
Operating lease liabilities	45	46
Other Liabilities, Current	173	166
Long-term deferred revenue	344	216
Long-term operating lease liabilities	211	230
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited Partners' Capital Account	$ 8,700	$ 8,413

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - shares	Dec. 31, 2023	Dec. 31, 2022
Units outstanding	1,003,498,875	1,001,020,616
Series A Preferred Stock [Member]
Series A preferred, Units Outstanding	27,200,000	30,000,000
Series B Preferred Stock [Member]
Preferred Units, Outstanding	0	600,000
Nonrelated Party | Common Stock [Member]
Units outstanding	356,000,000	354,000,000
Related Party
Units outstanding	647,415,452
Related Party | Common Stock [Member]
Units outstanding	647,000,000	647,000,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net income		$ 3,966	$ 3,978	$ 3,112
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs		55	73	70
Depreciation and amortization		1,213	1,230	1,287
Impairment expense		0	0	42
Deferred income taxes		3	3	(2)
Gain on sales-type leases and equity method investments		(92)	(509)	0
(Gain)/loss on disposal of assets		(14)	34	(13)
Income from equity method investments		(600)	(476)	(321)
Distributions from unconsolidated affiliates		736	578	508
Change in fair value of derivatives		0	(47)	45
Changes in:
Receivables		14	14	(199)
Inventories		(19)	(5)	(24)
Accounts payable and accrued liabilities		(40)	(33)	193
Assets/liabilities - related parties		84	40	101
Right of use assets/operating lease liabilities		0	(3)	(2)
Deferred revenue		107	108	88
All other, net		(16)	34	26
Net cash provided by operating activities		5,397	5,019	4,911
Investing activities:
Additions to property, plant and equipment		(937)	(806)	(529)
Acquisitions, net of cash acquired		(246)	(28)	0
Disposal of assets		26	84	126
Investments in unconsolidated affiliates		(98)	(217)	(151)
Distributions from unconsolidated affiliates - return of capital		3	11	36
Net cash used in investing activities		(1,252)	(956)	(518)
Financing activities:
Proceeds from long-term lines of credit		1,589	3,379	4,175
Repayments of Debt		1,001	2,202	5,821
Debt issuance costs		(15)	(29)	0
Unit repurchases	[1]	0	(491)	(630)
Distributions to noncontrolling interests		(41)	(38)	(39)
Distributions to unitholders and general partner		(3,181)	(2,921)	(3,432)
Contributions from MPC		31	44	45
All other, net		(2)	(4)	(2)
Net cash used in financing activities		(3,335)	(3,838)	(4,395)
Net change in cash, cash equivalents and restricted cash		810	225	(2)
Cash, cash equivalents and restricted cash at beginning of period		238	13	15
Cash, cash equivalents and restricted cash at end of period		1,048	238	13
Revolving Credit Facility
Financing activities:
Related party debt borrowings		0	2,989	8,493
Related party debt repayments		0	(4,439)	(7,043)
Series A Preferred Stock [Member]
Financing activities:
Distributions to Series A preferred unitholders		(94)	(85)	(100)
Series B Preferred Stock [Member]
Financing activities:
Redemption of Series B preferred units		(600)	0	0
Distributions to Series A preferred unitholders		$ (21)	$ (41)	$ (41)
[1] Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period.

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Common Unit-holder MPC	Series B Preferred Unit-holders	Accumulated Other Comprehensive Loss	Non-controlling Interests	Series A Preferred Unit-holders
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests							$ 968
Beginning Balance at Dec. 31, 2020	$ 13,017	$ 9,384	$ 2,792	$ 611	$ (15)	$ 245
Net income	(3,012)	(1,087)	(1,849)	(41)	0	(35)
Unit repurchases	(630)	(630)	0	0	0	0
Conversion of Series A preferred units	3	3	0	0	0	0
Distributions	(3,512)	(1,269)	(2,163)	(41)	0
Distributions to Noncontrolling Interest Holders						39
Contributions	160	0	160	0	0	0
Stockholders' Equity, Other	2	4	0	0	(2)	0
Temporary Equity Account, Distributions							100
Net income allocated							100
Temporary Equity, Other Changes							3
Ending Balance at Dec. 31, 2021	12,052	8,579	2,638	611	(17)	241
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests							965
Net income	(3,890)	(1,371)	(2,444)	(41)	0	(34)
Unit repurchases	(491)	(491)	0	0	0	0
Distributions	(3,000)	(1,050)	(1,871)	(41)	0
Distributions to Noncontrolling Interest Holders						38
Contributions	82	0	82	0	0	0
Stockholders' Equity, Other	13	4	0	0	9	0
Temporary Equity Account, Distributions							85
Net income allocated							88
Ending Balance at Dec. 31, 2022	12,546	8,413	3,293	611	(8)	237
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests	968						968
Net income	(3,872)	(1,336)	(2,493)	(5)	0	(38)
Conversion of Series A preferred units	73	73	0	0	0	0
Partners' Capital Account, Redemptions	(600)	(2)	(3)	(595)	0	0
Distributions	(3,243)	(1,125)	(2,056)	(21)	0
Distributions to Noncontrolling Interest Holders						41
Contributions	31	0	31	0	0	0
Stockholders' Equity, Other	10	5	0	0	4	1
Temporary Equity Account, Distributions							94
Net income allocated							94
Temporary Equity, Other Changes							73
Ending Balance at Dec. 31, 2023	12,689	$ 8,700	$ 3,758	$ 0	$ (4)	$ 235
Temporary Equity, Carrying Amount, Including Portion Attributable to Noncontrolling Interests	$ 895						$ 895

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2023
Limited Liability Company or Limited Partnership, Business Organization and Operations [Abstract]
Business Description and Basis of Presentation [Text Block]	Description of the Business and Basis of Presentation Description of the Business MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to 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. Basis of Presentation

Summary of Principal Accounting

Summary of Principal Accounting Policies	12 Months Ended
	Dec. 31, 2023
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, 2023 and 2022, MPLX’s asset retirement obligation was $39 million and $34 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. Certain commodity derivative positions are governed by master netting arrangements and are reflected on the consolidated balance sheets on a net basis by counterparty. 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 Product sales and Purchased product costs on the Consolidated Statements of Income. During the years ended December 31, 2023, 2022 and 2021, MPLX did not elect hedge accounting for any derivatives. 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. All the outstanding performance unit awards were 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, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Standards	Accounting Standards Recently Adopted ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers During 2023, we adopted ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. The adoption of this accounting standard update did not have a material impact on our financial statements. Not Yet Adopted ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures In November 2023, the FASB issued an ASU to update reportable segment disclosure requirements primarily by requiring enhanced disclosures about significant segment expenses. This ASU is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. The amendments should be applied retrospectively to all prior periods presented in the financial statements. We are currently evaluating the impact this ASU will have on our disclosures. ASU 2023-01, Leases (Topic 842): Common Control Arrangements In March 2023, the FASB issued an ASU to amend certain provisions of ASC 842 that apply to arrangements between related parties under common control. The ASU amends the accounting for the amortization period of leasehold improvements in common-control leases for all entities and requires certain disclosures when the lease term is shorter than the useful life of the asset. This ASU is effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted. We do not expect the application of this ASU to have a material impact on our consolidated financial statements or disclosures.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2023
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions and Dispositions Acquisition of 40 Percent Interest in MarkWest Torñado GP, L.L.C. On December 15, 2023, MPLX used $303 million of cash on hand to purchase the remaining 40 percent interest in MarkWest Torñado GP, L.L.C. (“Torñado”) for approximately $270 million, including cash paid for working capital, and to extend the term of a gathering and processing agreement for approximately $33 million. As a result of this transaction, we now own 100 percent of Torñado and reflect it as a consolidated subsidiary within our consolidated financial results. It was previously accounted for as an equity method investment. Torñado provides natural gas gathering and processing related services in the Permian basin. Its assets include two gas processing plants, each with a capacity of 200 MMcf/d and approximately 142 miles of gathering pipeline. The results for this business are reported under our G&P segment. At December 15, 2023, the carrying value of our 60 percent equity investment in Torñado was $311 million. Upon acquisition of the remaining 40 percent member interest, our existing equity investment was remeasured to fair value resulting in the recognition of a $92 million gain, which is presented in Other income on the Consolidated Statements of Income. The fair value of the previously-held equity method investment was primarily based on the price negotiated for the 40 percent interest in Torñado. The acquisition was accounted for as a business combination requiring all of the Torñado assets and liabilities to be remeasured to fair value resulting in a consolidated fair value of net assets and liabilities of $673 million. The fair value of property, plant and equipment is based primarily on the cost approach. The fair value of the identifiable intangible assets, consisting of various customer contracts, was primarily based on the multi-period excess earnings method, which is an income approach. The following table reflects our determination of the fair value of the Torñado assets and liabilities (in millions): (In millions) Property, Plant and Equipment $ 583 Intangibles 77 Working capital, net 30 Other Long-term assets and liabilities, net (17) Total net assets and liabilities $ 673 Pro forma financial information assuming the acquisition had occurred as of the beginning of the calendar year prior to the year of the acquisition, as well as the revenues and earnings generated during the period since the acquisition date, were not material for disclosure purposes. Sale of Javelina On February 12, 2021, MPLX completed the sale of its 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, 2023 and 2022. Prior to the sale, Javelina was reported within the G&P segment.

Investments and Noncontrolling

Investments and Noncontrolling Interests	12 Months Ended
	Dec. 31, 2023
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 2023 2023 2022 L&S Andeavor Logistics Rio Pipeline LLC X 67% $ 171 $ 177 Illinois Extension Pipeline Company, L.L.C. 35% 228 236 LOOP LLC 41% 314 287 MarEn Bakken Company LLC (1) 25% 449 475 Minnesota Pipe Line Company, LLC 17% 174 178 Whistler Pipeline LLC 38% 214 211 Other (2) X 282 269 Total L&S 1,832 1,833 G&P Centrahoma Processing LLC 40% 114 131 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. X 67% 336 335 MarkWest Torñado GP, L.L.C. (3) 100% — 306 MarkWest Utica EMG, L.L.C. X 58% 676 669 Rendezvous Gas Services, L.L.C. X 78% 129 137 Sherwood Midstream Holdings LLC X 51% 113 125 Sherwood Midstream LLC X 50% 500 512 Other (2) X 43 47 Total G&P 1,911 2,262 Total $ 3,743 $ 4,095 (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”). (2) Some investments included within Other have also been deemed to be VIEs. (3) At December 31, 2022, we owned a 60 percent interest in Torñado. On December 15, 2023, we acquired the remaining 40 percent interest. As a result of acquiring the remaining interest, we obtained control of and now consolidate Torñado. For those entities that have been deemed to be VIEs, neither MPLX nor any of its subsidiaries have been deemed to be the primary beneficiary due to voting rights on significant matters. While we have the ability to exercise influence through participation in the management committees which make all significant decisions, we have equal influence over each committee as a joint interest partner and all significant decisions require the consent of the other investors without regard to economic interest. As such, we have determined that these entities should not be consolidated and applied 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, 2023, 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, 2023, 2022 and 2021. See Note 21 for information on our Guarantees related to indebtedness of equity method investees. From time to time, changes in the design or nature of the activities of our equity method investments may require us to reconsider our conclusions on the entity’s status as a VIE and/or our status as the primary beneficiary. Such reconsideration could result in a change in the classification of the equity method investment. Summarized financial information for MPLX’s equity method investments for the years ended December 31, 2023, 2022 and 2021 is as follows: 2023 (In millions) VIEs Non-VIEs Total Revenues and other income $ 806 $ 2,456 $ 3,262 Costs and expenses 336 995 1,331 Income from operations 470 1,460 1,930 Net income 437 1,197 1,634 Income from equity method investments $ 238 $ 362 $ 600 2022 (In millions) 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 2021 (In millions) 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 Summarized balance sheet information for MPLX’s equity method investments as of December 31, 2023 and 2022 is as follows: December 31, 2023 (In millions) VIEs Non-VIEs Total Current assets $ 148 $ 1,383 $ 1,531 Noncurrent assets 3,757 10,103 13,860 Current liabilities 80 899 979 Noncurrent liabilities $ 559 $ 4,297 $ 4,856 December 31, 2022 (In millions) 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 As of December 31, 2023 and 2022, the underlying net assets of MPLX’s investees in the G&P segment exceeded the carrying value of its equity method investments by approximately $45 million and $51 million, respectively. As of December 31, 2023 and 2022, the carrying value of MPLX’s equity method investments in the L&S segment exceeded the underlying net assets of its investees by $314 million and $320 million, respectively. At both December 31, 2023 and 2022, the G&P basis difference related to goodwill was $31 million. At both December 31, 2023 and 2022, 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, 2023
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; and 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 agreements. 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 marine transportation agreements with initial terms of five • 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 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 Agreement with MPC MPLX has an 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 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 bear interest at 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. There was no activity on the MPC Loan Agreement for the year ended December 31, 2023. Activity on the MPC Loan Agreement for the years ended December 31, 2022 and 2021 was as follows: (In millions, except %) 2022 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 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 and other related parties 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, 2023, 2022 and 2021, these sales totaled $739 million, $1,002 million and $811 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. For the years ended December 31, 2023, 2022 and 2021, General and administrative expenses incurred from MPC totaled $262 million, $235 million and $250 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 2023, 2022 and 2021, these charges totaled $94 million, $70 million and $55 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) 2023 2022 Current assets - related parties Receivables $ 587 $ 610 Lease receivables 149 111 Prepaid 5 5 Other 7 3 Total 748 729 Noncurrent assets - related parties Long-term lease receivables 789 883 Right of use assets 227 228 Unguaranteed residual asset 126 87 Long-term receivables 19 27 Total 1,161 1,225 Current liabilities - related parties MPC loan agreement and other payables (1) 278 262 Deferred revenue 81 80 Operating lease liabilities 1 1 Total 360 343 Long-term liabilities - related parties Long-term operating lease liabilities 226 228 Long-term deferred revenue 99 110 Total $ 325 $ 338 (1) There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2023 or 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.

Equity

Equity	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Equity	Equity Units Outstanding MPLX had 1,003,498,875 common units outstanding as of December 31, 2023. Of that number, 647,415,452 were owned by MPC. The table below summarizes the changes in the number of units outstanding for the years ended December 31, 2021, 2022, and 2023: (In units) Total Common Units 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 Unit-based compensation awards 196,428 Conversion of Series A preferred units 2,281,831 Balance at December 31, 2023 1,003,498,875 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, 2023, 2022 and 2021: (In millions, except per unit data) 2023 2022 2021 Number of units repurchased — 15 23 Cash paid for units repurchased (1) $ — $ 491 $ 630 Average cost per unit (1) $ — $ 31.96 $ 27.52 (1) Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period. As of December 31, 2023, we had $846 million available under our remaining unit repurchase authorization. Series A Redeemable Preferred Unit Conversions Since 2020, certain Series A preferred unitholders have exercised their rights to convert their Series A preferred units into approximately 2.4 million common units as discussed in Note 9. Redemption of the Series B Preferred Units On February 15, 2023, MPLX exercised its right to redeem all 600,000 units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units (the “Series B preferred units”). MPLX paid unitholders the Series B preferred unit redemption price of $1,000 per unit. Distributions on the Series B preferred units were 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. In accordance with these terms, MPLX made a final cash distribution of $21 million to Series B preferred unitholders on February 15, 2023, in conjunction with the redemption. The changes in the Series B preferred unit balance during 2023, 2022 and 2021 are included in the Consolidated Statements of Equity within Series B preferred units. Cash Distributions Total distributions for the years ended December 31, 2023, 2022 and 2021 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. 2023 2022 2021 Distributions per common unit $ 3.25 $ 2.96 $ 3.36 The allocation of total quarterly cash distributions to limited, and preferred unitholders is as follows for the years ended December 31, 2023, 2022 and 2021. 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) 2023 2022 2021 Common and preferred unit distributions: Common unitholders, includes common units of general partner (1) $ 3,256 $ 2,980 $ 3,432 Series A preferred unit distributions (1) 94 88 100 Series B preferred unit distributions (2) 5 41 41 Total cash distributions declared $ 3,355 $ 3,109 $ 3,573 (1) 2021 period includes the Supplemental Distribution Amount. (2) 2023 period includes the portion of the $21 million distribution paid to the Series B preferred unitholders on February 15, 2023 that was earned during the period prior to the redemption.

Net Income (Loss) Per Limited P

Net Income (Loss) Per Limited Partner Unit	12 Months Ended
	Dec. 31, 2023
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 2023, 2022 and 2021, 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, 2023, 2022 and 2021 were less than 1 million. (In millions) 2023 2022 2021 Net income attributable to MPLX LP (1) $ 3,928 $ 3,944 $ 3,077 Less: Distributions declared on Series A preferred units (2) 94 88 100 Distributions declared on Series B preferred units 5 41 41 Limited partners’ distributions declared on MPLX common units (including common units of general partner) (2) 3,256 2,980 3,432 Undistributed net income/(loss) attributable to MPLX LP $ 573 $ 835 $ (496) (1) The year ended December 31, 2022 includes a $509 million gain on a lease reclassification. See Note 20 for additional information. (2) The year ended December 31, 2021 includes the Supplemental Distribution Amount. 2023 (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 $ 3,256 $ 94 $ 5 $ 3,355 Undistributed net income attributable to MPLX LP 557 16 — 573 Net income attributable to MPLX LP (1) $ 3,813 $ 110 $ 5 $ 3,928 Impact of redemption of Series B preferred units (5) (5) Income available to common unitholders $ 3,808 $ 3,923 Weighted average units outstanding: Basic 1,001 Diluted 1,002 Net income attributable to MPLX LP per limited partner unit: Basic $ 3.80 Diluted $ 3.80 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) Includes a $509 million 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 loss attributable to MPLX LP per unit: Net income attributable to MPLX LP: Distribution 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.

Redeemable Preferred Units

Redeemable Preferred Units	12 Months Ended
	Dec. 31, 2023
Redeemable Preferred Units Disclosure [Abstract]
Preferred Stock	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 24, 2024, MPLX declared a quarterly cash distribution of $0.8500 per common unit for the fourth quarter of 2023. 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 years ended December 31, 2023 and December 31, 2021, certain Series A preferred unitholders exercised their rights to convert their Series A preferred units into 2,281,831 common units and 93,108 common units, respectively. Approximately 27.2 million Series A preferred units remain outstanding as of December 31, 2023. 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, 2023, 2022 and 2021, see the Consolidated Statements of Equity.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Segment Information	Segment Information MPLX’s chief operating decision maker (“CODM”) is the chief executive officer of its general partner. The CODM 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 CODM 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 and equity method investments; (vi) impairment expense; (vii) noncontrolling interests; and (viii) other adjustments as applicable. 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 CODM and thus are not reported in our disclosures. The tables below present information about revenues and other income, Segment Adjusted EBITDA, capital expenditures and investments in unconsolidated affiliates for our reportable segments: (In millions) 2023 2022 2021 L&S Service revenue $ 4,335 $ 4,057 $ 3,918 Rental income 857 803 772 Product related revenue 18 19 14 Sales-type lease revenue 500 465 435 Income from equity method investments 345 267 153 Other income 68 57 61 Total segment revenues and other income (1) 6,123 5,668 5,353 Segment Adjusted EBITDA (2) 4,228 3,818 3,681 Capital expenditures 414 325 316 Investments in unconsolidated affiliates 26 97 33 G&P Service revenue 2,189 2,056 2,023 Rental income 208 287 347 Product related revenue 2,191 2,792 2,066 Sales-type lease revenue 136 62 — Income from equity method investments 255 209 168 Other income (3) 179 539 70 Total segment revenues and other income (1) 5,158 5,945 4,674 Segment Adjusted EBITDA (2) 2,041 1,957 1,879 Capital expenditures 605 528 224 Investments in unconsolidated affiliates $ 72 $ 120 $ 118 (1) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $776 million, $644 million and $503 million for the years ended December 31, 2023, 2022 and 2021, respectively. Third party revenues for the G&P segment were $4,827 million, $5,678 million and $4,463 million for the years ended December 31, 2023, 2022 and 2021, respectively. (2) See below for the reconciliation from Segment Adjusted EBITDA to Net income. (3) Includes a $92 million gain on remeasurement of our existing equity investment in Torñado in conjunction with the purchase of the remaining joint venture interest in 2023. Includes a $509 million 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 and Segment Adjusted EBITDA. (In millions) 2023 2022 2021 Reconciliation to Net income: L&S Segment Adjusted EBITDA $ 4,228 $ 3,818 $ 3,681 G&P Segment Adjusted EBITDA 2,041 1,957 1,879 Total reportable segments 6,269 5,775 5,560 Depreciation and amortization (1) (1,213) (1,230) (1,287) Interest and other financial costs (923) (925) (879) Income from equity method investments 600 476 321 Distributions/adjustments related to equity method investments (774) (652) (537) Gain on sales-type leases and equity method investments 92 509 — Impairment expense — — (42) Adjusted EBITDA attributable to noncontrolling interests 42 38 39 Garyville incident response costs (2) (16) — — Other (3) (111) (13) (63) Net income $ 3,966 $ 3,978 $ 3,112 (1) Depreciation and amortization attributable to L&S was $530 million, $515 million and $546 million for the years ended December 31, 2023, 2022 and 2021, respectively. Depreciation and amortization attributable to G&P was $683 million, $715 million and $741 million for the years ended December 31, 2023, 2022 and 2021, respectively. (2) In August 2023, a naphtha release and resulting fire occurred at our Garyville Tank Farm resulting in the loss of four storage tanks with a combined shell capacity of 894 thousand barrels. We incurred $16 million of incident response costs, net of insurance recoveries, during the year ended December 31, 2023. (3) Includes unrealized derivative gain/(loss), 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, 2023
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. 2023 2022 2021 Total revenues and other income (1) L&S 87 % 88 % 90 % G&P 5 % 4 % 3 % Total 50 % 47 % 50 % (1) The percent calculations for the year ended December 31, 2023 exclude a $92 million gain associated with the remeasurement of its existing equity investment in Torñado. The percent calculations for the year ended December 31, 2022 exclude a $509 million gain on a lease reclassification. 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. For the year ended December 31, 2023, revenues with one customer primarily related to these NGL transactions accounted for approximately 10 percent of our total revenues and other income for the year ended December 31, 2023. 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, 2023
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: December 31, (In millions) 2023 2022 NGLs $ 8 $ 6 Line fill 15 16 Spare parts, materials and supplies 136 126 Total inventories $ 159 $ 148

Goodwill and Intangibles

Goodwill and Intangibles	12 Months Ended
	Dec. 31, 2023
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, 2023, 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 10.2 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, 2023 was $7,645 million and no impairment was recorded as a result of our November 30, 2023 annual goodwill impairment analysis. 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, 2021 $ 7,657 $ 3,141 $ 10,798 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2021 7,657 — 7,657 Disposal of assets (12) — (12) Balance as of December 31, 2022 7,645 — 7,645 Balance as of December 31, 2023 7,645 — 7,645 Gross goodwill as of December 31, 2023 7,645 3,141 10,786 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2023 $ 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, 2023 and 2022 is shown below: December 31, 2023 December 31, 2022 (In millions) Gross Accumulated Amortization (1) Net Gross Accumulated Amortization (1) Net L&S $ 283 $ (189) $ 94 $ 283 $ (153) $ 130 G&P 1,365 (805) 560 1,288 (713) 575 $ 1,648 $ (994) $ 654 $ 1,571 $ (866) $ 705 (1) Amortization expense attributable to the L&S segment for both years ended December 31, 2023 and 2022 was $36 million. Amortization expense attributable to the G&P segment for the years ended December 31, 2023 and 2022 was $92 million and $90 million, respectively. Estimated future amortization expense related to the intangible assets at December 31, 2023 is as follows: (In millions) 2024 $ 134 2025 121 2026 112 2027 84 2028 67 2029 and thereafter 136 Total $ 654

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Measurements Fair Values – Recurring The following table presents the impact on the Consolidated Balance Sheets of MPLX’s financial instruments carried at fair value on a recurring basis as of December 31, 2023 and 2022 by fair value hierarchy level. December 31, 2023 2022 (In millions) Asset Liability Asset Liability Embedded derivatives in commodity contracts (Level 3) Other current assets / Other current liabilities $ — $ 11 $ — $ 10 Other noncurrent assets / Other long-term liabilities — 50 — 51 Total carrying value in Consolidated Balance Sheets $ — $ 61 $ — $ 61 Level 2 instruments include over-the-counter fixed swaps to mitigate the price risk from our sales of propane. The swap valuations are based on observable inputs in the form of forward prices based on Mont Belvieu propane forward spot prices and contain no significant unobservable inputs. All of our Level 2 instruments were settled during 2023. There were no positions outstanding as of December 31, 2023. Level 3 instruments relate to an embedded derivative liability for a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.61 to $1.44 per gallon with a weighted average of $0.76 per gallon and (2) a 100 percent probability of renewal for the five Changes in Level 3 Fair Value Measurements The following table is a reconciliation of the net beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. (In millions) 2023 2022 Beginning balance $ (61) $ (108) Unrealized and realized (loss)/gain included in Net Income (1) (11) 35 Settlements 11 12 Ending balance (61) (61) The amount of total (loss)/gain for the period included in earnings attributable to the change in unrealized gain relating to liabilities still held at end of period $ (9) $ 33 (1) (Loss)/gain on derivatives embedded in commodity contracts are recorded in Purchased product costs Fair Values – Non-recurring Non-recurring fair value measurements and disclosures in 2023 relate primarily to the acquisition of the remaining interest in Torñado as discussed in Note 4. Non-recurring fair value measurements and disclosures in 2022 and 2021 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 (see Note 16). The fair value of MPLX’s debt is estimated based on prices from recent trade activity and is categorized in Level 3 of the fair value hierarchy. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs: December 31, 2023 2022 (In millions) Fair Value Carrying Value Fair Value Carrying Value Outstanding debt (1) $ 19,377 $ 20,547 $ 18,095 $ 19,905 (1) Any 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, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments During the year ended December 31, 2023, MPLX entered into commodity contracts that were executed to manage price risk during 2023. All of those positions were settled during 2023, with the associated gains included in the table below. As of December 31, 2023, MPLX had no outstanding commodity contracts beyond the embedded derivative discussed below. Embedded Derivative - MPLX has a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2027. The customer has the unilateral option to extend the agreement for one five decision points that may exist at the time they would elect whether to renew the contract. The changes in fair value of this compound embedded derivative are based on the difference between the contractual and index pricing, the probability of the producer customer exercising its option to extend, and the estimated favorability of these contracts compared to current market conditions. The changes in fair value are recorded in earnings through Purchased product costs in the Consolidated Statements of Income. For further information regarding the fair value measurement of derivative instruments, see Note 15. See Note 2 for a discussion of derivatives MPLX may use and the reasons for them. As of both December 31, 2023 and 2022, the estimated fair value of this contract was a liability of $61 million. As of December 31, 2023 and 2022, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized in the Consolidated Statements of Income is summarized below: (In millions) 2023 2022 2021 Product sales Realized gain $ 7 $ — $ — Product sales derivative gain 7 — — Purchased product costs Realized loss (11) (12) (14) Unrealized gain/(loss) — 47 (45) Purchased product cost derivative (loss)/gain (11) 35 (59) Total derivative (loss)/gain included in Net Income $ (4) $ 35 $ (59)

Debt

Debt	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt	Debt MPLX’s outstanding borrowings at December 31, 2023 and 2022 consisted of the following: December 31, (In millions) 2023 2022 MPLX LP: Bank revolving credit facility $ — $ — 4.500% senior notes due July 15, 2023 — 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 1,000 5.000% senior notes due March 1, 2033 1,100 — 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 1,500 5.650% senior notes due March 1, 2053 500 — 4.900% senior notes due April 15, 2058 500 500 Consolidated subsidiaries: MarkWest - 4.500% - 4.875% senior notes, due 2023-2025 12 23 ANDX - 4.250% - 5.200% senior notes, due 2027-2047 31 31 Financing lease obligations (1) 6 8 Total 20,706 20,108 Unamortized debt issuance costs (122) (117) Unamortized discount (153) (195) Amounts due within one year (1,135) (988) Total long-term debt due after one year $ 19,296 $ 18,808 (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, 2023: (In millions) 2024 $ 1,151 2025 1,701 2026 1,501 2027 2,001 2028 $ 1,250 Credit Agreements MPLX Credit Agreement MPLX’s credit agreement (the “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, 2023, MPLX was in compliance with the covenants contained in the MPLX Credit Agreement. Activity on the MPLX Credit Agreement was as follows: December 31, (In millions, except %) 2023 2022 Borrowings $ — $ 900 Weighted average interest rate of borrowings — % 1.45 % Repayments $ — $ 1,200 Outstanding balance at end of period $ — $ — Letters of credit outstanding $ 0.2 $ 0.2 Total remaining availability on facility $ 2,000 $ 2,000 Percent of borrowing capacity available 100 % 100 % 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 4.875% 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 5.000% senior notes due March 1, 2033 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 5.650% senior notes due March 1, 2053 March 1 st and September 1 st 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. On February 15, 2023, MPLX used $600 million of the net proceeds from the offering of the 2033 Senior Notes and 2053 Senior Notes described above to redeem all of the outstanding Series B preferred units. On March 13, 2023, MPLX used the remaining proceeds from the offering, and cash on hand, to redeem all of MPLX’s and MarkWest’s $1.0 billion aggregate principal amount of 4.50 percent senior notes due July 2023, at par, plus accrued and unpaid interest. The redemption resulted in a loss of $9 million due to the immediate expense recognition of unamortized debt discount and issuance costs, which is included on the Consolidated Statements of Income as Other financial costs, net. 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, net. 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, 2023
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, 2023, 2022 and 2021: 2023 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 369 $ 2,170 $ 2,539 Service revenue - related parties 3,966 19 3,985 Service revenue - product related — 294 294 Product sales 5 1,660 1,665 Product sales - related parties 13 237 250 Total revenues from contracts with customers $ 4,353 $ 4,380 8,733 Non-ASC 606 revenue (1) 2,548 Total revenues and other income $ 11,281 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 (1) Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income. Contract Balances Our receivables are primarily associated with customer contracts. Payment terms vary by product or service type; however, the period between invoicing and payment is not significant. Included within the receivables are balances related to commodity sales on behalf of our producer customers, for which we remit the net sales price back to the producer customers upon completion of the sale. Under certain of our contracts, we recognize revenues in excess of billings which we present as contract assets. 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. Under certain of our contracts, we receive payments in advance of satisfying our performance obligations, which are recorded as contract liabilities. 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. The tables below reflect the changes in ASC 606 contract balances for the years ended December 31, 2023 and 2022: (In millions) Balance at Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 21 $ (18) $ — $ 3 Long-term contract assets 1 — — 1 Deferred revenue 57 42 (40) 59 Deferred revenue - related parties 63 86 (102) 47 Long-term deferred revenue 216 128 — 344 Long-term deferred revenue - related parties 25 4 — 29 Long-term contract liabilities $ 2 $ (2) $ — $ — (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 (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) as of December 31, 2023. The amounts presented below are generally limited to fixed consideration from contracts with customers that contain minimum volume commitments. A significant portion of our future contracted revenue is excluded from the amounts presented below in accordance with ASC 606. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded from this disclosure. Additionally, we do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less, or that are terminable by our customer with little or no termination penalties. Potential future performance obligations related to renewals that have not yet been exercised or are not certain of exercise are excluded from the amounts presented below. Revenues classified as Rental income and Sales-type lease revenue are also excluded from this table. (In billions) 2024 $ 2.0 2025 1.9 2026 1.8 2027 1.7 2028 0.5 2029 and thereafter 0.6 Total revenue on remaining performance obligations $ 8.5 As of December 31, 2023, unsatisfied performance obligations included in the Consolidated Balance Sheets are $479 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 20 years. A portion of this amount is not disclosed in the table above as it is deemed variable consideration due to volume variability.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2023
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information (In millions) 2023 2022 2021 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 893 $ 813 $ 812 Income taxes paid 7 3 4 Cash paid for amounts included in the measurement of lease liabilities: Payments on operating leases 71 73 79 Net cash provided by financing activities included: Principal payments under finance lease obligations 1 2 2 Non-cash investing and financing activities: Net transfers of property, plant and equipment (to)/from materials and supplies inventories (8) (1) 1 ROU assets obtained in exchange for new operating lease obligations 21 78 20 ROU assets obtained in exchange for new finance lease obligations — 1 — Book value of equity method investment (1) 311 — — (1) Represents the book value of MPLX’s equity method investment in Torñado prior to MPLX buying out the remaining interest in this entity. See Note 4 for additional information. 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) 2023 2022 2021 Additions to property, plant and equipment $ 937 $ 806 $ 529 Increase in capital accruals 82 47 11 Total capital expenditures $ 1,019 $ 853 $ 540

Leases (Notes)

Leases (Notes)	12 Months Ended
	Dec. 31, 2023
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: 2023 2022 2021 (In millions) Related Party Third Related Third Related Third Components of lease costs: Operating lease costs $ 14 $ 56 $ 15 $ 61 $ 15 $ 71 Finance lease cost: Amortization of ROU assets — 1 — 1 — 2 Interest on lease liabilities — — — 1 — 1 Total finance lease cost — 1 — 2 — 3 Variable lease cost 4 10 2 16 — 15 Short-term lease cost 1 61 — 45 — 31 Total lease cost $ 19 $ 128 $ 17 $ 124 $ 15 $ 120 Supplemental balance sheet data related to leases were as follows: December 31, 2023 December 31, 2022 (In millions, except % and years) Related Party Third Party Related Party Third Party Operating leases Assets Right of use assets $ 227 $ 264 $ 228 $ 283 Liabilities Operating lease liabilities 1 45 1 46 Long-term operating lease liabilities 226 211 228 230 Total operating lease liabilities $ 227 $ 256 $ 229 $ 276 Weighted average remaining lease term 43 years 9 years 44 years 9 years Weighted average discount rate 5.8 % 4.2 % 5.8 % 4.1 % Finance leases Assets Property, plant and equipment, gross $ 10 $ 11 Less: Accumulated depreciation 5 4 Property, plant and equipment, net 5 7 Liabilities Long-term debt due within one year 1 1 Long-term debt 5 7 Total finance lease liabilities $ 6 $ 8 Weighted average remaining lease term 20 years 18 years Weighted average discount rate 6.0 % 6.0 % As of December 31, 2023, 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 2024 $ 15 $ 55 $ 1 2025 14 40 1 2026 14 35 1 2027 14 31 1 2028 14 29 1 2029 and thereafter 547 115 6 Gross lease payments 618 305 11 Less: Imputed interest 391 49 5 Total lease liabilities $ 227 $ 256 $ 6
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: 2023 2022 2021 (In millions) Related Party Third Related Third Related Third Components of lease costs: Operating lease costs $ 14 $ 56 $ 15 $ 61 $ 15 $ 71 Finance lease cost: Amortization of ROU assets — 1 — 1 — 2 Interest on lease liabilities — — — 1 — 1 Total finance lease cost — 1 — 2 — 3 Variable lease cost 4 10 2 16 — 15 Short-term lease cost 1 61 — 45 — 31 Total lease cost $ 19 $ 128 $ 17 $ 124 $ 15 $ 120 Supplemental balance sheet data related to leases were as follows: December 31, 2023 December 31, 2022 (In millions, except % and years) Related Party Third Party Related Party Third Party Operating leases Assets Right of use assets $ 227 $ 264 $ 228 $ 283 Liabilities Operating lease liabilities 1 45 1 46 Long-term operating lease liabilities 226 211 228 230 Total operating lease liabilities $ 227 $ 256 $ 229 $ 276 Weighted average remaining lease term 43 years 9 years 44 years 9 years Weighted average discount rate 5.8 % 4.2 % 5.8 % 4.1 % Finance leases Assets Property, plant and equipment, gross $ 10 $ 11 Less: Accumulated depreciation 5 4 Property, plant and equipment, net 5 7 Liabilities Long-term debt due within one year 1 1 Long-term debt 5 7 Total finance lease liabilities $ 6 $ 8 Weighted average remaining lease term 20 years 18 years Weighted average discount rate 6.0 % 6.0 % As of December 31, 2023, 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 2024 $ 15 $ 55 $ 1 2025 14 40 1 2026 14 35 1 2027 14 31 1 2028 14 29 1 2029 and thereafter 547 115 6 Gross lease payments 618 305 11 Less: Imputed interest 391 49 5 Total lease liabilities $ 227 $ 256 $ 6
Lessor, Operating Leases	Lessor Certain fee-based transportation and storage services agreements with MPC and third parties and certain fee-based natural gas transportation and processing agreements with third parties are accounted for as operating leases under ASC 842. The transportation and storage agreements have remaining terms ranging from less than one year to nine years with renewal options ranging from one year to five years, with some agreements having multiple renewal options. The primary terms of the natural gas transportation and processing 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. 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 years ended December 31, 2022 and 2021, 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. Lease revenues included on the Consolidated Statements of Income during 2023, 2022 and 2021 were as follows: 2023 2022 2021 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 822 $ 243 $ 763 $ 327 $ 743 $ 376 Sales-type leases: Interest income (Sales-type rental revenue - fixed minimum) 467 114 447 46 431 — Interest income (Revenue from variable lease payments) 33 22 18 16 4 — Sales-type lease revenue $ 500 $ 136 $ 465 $ 62 $ 435 $ — 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. 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. There were no amounts to report for the year ended December 31, 2023. 2022 2021 (In millions) Related Party (1) Third Party (2) Related Party (1) Third Lease receivables $ 87 $ 914 $ 519 $ — Unguaranteed residual assets 6 63 14 — Property, plant and equipment, net (50) (745) (421) — Deferred revenue — 277 — — Amount recognized on commencement date $ 43 $ 509 $ 112 $ — (1) The amount recognized on commencement date was recorded as a Contribution from MPC in the Consolidated Statements of Equity given the underlying agreements are between entities under common control. (2) The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income. The following is a schedule of minimum future rental payments on the non-cancellable operating leases as of December 31, 2023: (In millions) Related Party Third Party Total 2024 $ 759 $ 117 $ 876 2025 737 95 832 2026 590 75 665 2027 447 53 500 2028 168 46 214 2029 and thereafter 47 250 297 Total minimum future rentals $ 2,748 $ 636 $ 3,384 Annual minimum undiscounted lease payment receipts under our sales-type leases were as follows as of December 31, 2023: (In millions) Related Party Third Party Total 2024 $ 503 $ 175 $ 678 2025 504 161 665 2026 472 150 622 2027 359 141 500 2028 86 132 218 2029 and thereafter 128 959 1,087 Total minimum future rentals 2,052 1,718 3,770 Less: Imputed interest 1,114 778 1,892 Lease receivable (1) $ 938 940 1,878 Current lease receivables (2) 149 102 251 Long-term lease receivables (3) 789 838 1,627 Unguaranteed residual assets (3) 126 78 204 Total sales-type lease assets $ 1,064 $ 1,018 $ 2,082 (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, 2023 and 2022: December 31, (In millions) 2023 2022 Pipelines $ 677 $ 670 Refining logistics 1,399 1,310 Terminals 1,267 1,241 Marine 126 126 Gathering and transportation 86 94 Processing and fractionation 1,000 973 Land, building and other 165 163 Total property, plant and equipment 4,720 4,577 Less: accumulated depreciation 2,124 1,880 Property, plant and equipment, net $ 2,596 $ 2,697 Capital expenditures related to assets subject to sales-type lease arrangements were $85 million, $72 million and $48 million for the years ended December 31, 2023, 2022 and 2021, respectively. These amounts are reflected as Additions to property, plant and equipment in the Consolidated Statements of Cash Flows.
Lessor, Sales-type Leases	Lessor Certain fee-based transportation and storage services agreements with MPC and third parties and certain fee-based natural gas transportation and processing agreements with third parties are accounted for as operating leases under ASC 842. The transportation and storage agreements have remaining terms ranging from less than one year to nine years with renewal options ranging from one year to five years, with some agreements having multiple renewal options. The primary terms of the natural gas transportation and processing 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. 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 years ended December 31, 2022 and 2021, 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. Lease revenues included on the Consolidated Statements of Income during 2023, 2022 and 2021 were as follows: 2023 2022 2021 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 822 $ 243 $ 763 $ 327 $ 743 $ 376 Sales-type leases: Interest income (Sales-type rental revenue - fixed minimum) 467 114 447 46 431 — Interest income (Revenue from variable lease payments) 33 22 18 16 4 — Sales-type lease revenue $ 500 $ 136 $ 465 $ 62 $ 435 $ — 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. 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. There were no amounts to report for the year ended December 31, 2023. 2022 2021 (In millions) Related Party (1) Third Party (2) Related Party (1) Third Lease receivables $ 87 $ 914 $ 519 $ — Unguaranteed residual assets 6 63 14 — Property, plant and equipment, net (50) (745) (421) — Deferred revenue — 277 — — Amount recognized on commencement date $ 43 $ 509 $ 112 $ — (1) The amount recognized on commencement date was recorded as a Contribution from MPC in the Consolidated Statements of Equity given the underlying agreements are between entities under common control. (2) The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income. The following is a schedule of minimum future rental payments on the non-cancellable operating leases as of December 31, 2023: (In millions) Related Party Third Party Total 2024 $ 759 $ 117 $ 876 2025 737 95 832 2026 590 75 665 2027 447 53 500 2028 168 46 214 2029 and thereafter 47 250 297 Total minimum future rentals $ 2,748 $ 636 $ 3,384 Annual minimum undiscounted lease payment receipts under our sales-type leases were as follows as of December 31, 2023: (In millions) Related Party Third Party Total 2024 $ 503 $ 175 $ 678 2025 504 161 665 2026 472 150 622 2027 359 141 500 2028 86 132 218 2029 and thereafter 128 959 1,087 Total minimum future rentals 2,052 1,718 3,770 Less: Imputed interest 1,114 778 1,892 Lease receivable (1) $ 938 940 1,878 Current lease receivables (2) 149 102 251 Long-term lease receivables (3) 789 838 1,627 Unguaranteed residual assets (3) 126 78 204 Total sales-type lease assets $ 1,064 $ 1,018 $ 2,082 (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, 2023 and 2022: December 31, (In millions) 2023 2022 Pipelines $ 677 $ 670 Refining logistics 1,399 1,310 Terminals 1,267 1,241 Marine 126 126 Gathering and transportation 86 94 Processing and fractionation 1,000 973 Land, building and other 165 163 Total property, plant and equipment 4,720 4,577 Less: accumulated depreciation 2,124 1,880 Property, plant and equipment, net $ 2,596 $ 2,697 Capital expenditures related to assets subject to sales-type lease arrangements were $85 million, $72 million and $48 million for the years ended December 31, 2023, 2022 and 2021, respectively. 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, 2023
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, 2023 and 2022, accrued liabilities for remediation totaled $ 19 million 17 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 (collectively, 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 seeking disgorgement of pipeline profits from June 1, 2013 to present, removal of the pipeline and remediation. On November 8, 2023, the Court granted THPP’s motion to sever and stay the U.S. Government Parties’ counterclaims. The case will proceed on the merits of THPP’s challenge to the March 2021 order purporting to vacate all previous orders related to THPP’s alleged trespass. THPP continues not to operate that portion of the pipeline that crosses the property at issue. MPLX is also a party to a number of other lawsuits and other proceedings arising in the ordinary course of business. While the ultimate outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these other lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated financial position, results of operations or cash flows. 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, which owns and operates the Bakken Pipeline system. In 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the United States 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 Army Corps issued a draft EIS in September 2023 detailing various options for the easement, including denying the easement, approving the easement with additional measures, rerouting the easement, or approving the easement with no changes. The Army Corps has not selected a preferred alternative, but will make a decision in its final review, after considering input from the public and other agencies. The pipeline remains operational while the Army Corps finalizes its decision which is expected to be issued by the end of 2024. 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 vacation of the easement results in a temporary shutdown of the pipeline, 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 easement and/or return the pipeline into operation. If the vacation of the easement 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, 2023, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million. Contractual Commitments and Contingencies At December 31, 2023, MPLX’s contractual commitments to acquire property, plant and equipment totaled $136 million. 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, 2023, 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, terminalling, and gathering and processing agreements that obligate us to minimum volume, throughput or payment commitments over the remaining terms, which range from less than one year to eight years. After the minimum volume commitments are met in these agreements, MPLX pays additional amounts based on throughput. These agreements may include escalation clauses based on various inflationary indices; however, those potential increases have not been incorporated in minimum fees due under these agreements presented below. The minimum future payments under these agreements as of December 31, 2023 are as follows: (In millions) 2024 $ 187 2025 157 2026 145 2027 130 2028 120 2029 and thereafter 94 Total $ 833

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Pay vs Performance Disclosure
Net income attributable to MPLX LP(1)	$ 3,928	$ 3,944	[1]	$ 3,077
[1]The year ended December 31, 2022 includes a $509 million gain on a lease reclassification. See Note 20 for additional information.

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During the quarter ended December 31, 2023, no director or officer (as defined in Rule 16a-1(f) promulgated under the Exchange Act) of MPLX adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement” (as each term is defined in Item 408 of Regulation S-K).
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Description of Business and B_2

Description of Business and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2023
Limited Liability Company or Limited Partnership, Business Organization and Operations [Abstract]
Basis of presentation	Basis of Presentation

Summary of Principal Accounti_2

Summary of Principal Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
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. 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	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	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 Intangibles	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 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	Asset Retirement Obligations
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. Certain commodity derivative positions are governed by master netting arrangements and are reflected on the consolidated balance sheets on a net basis by counterparty. 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 Product sales and Purchased product costs on the Consolidated Statements of Income. During the years ended December 31, 2023, 2022 and 2021, MPLX did not elect hedge accounting for any derivatives. 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. All the outstanding performance unit awards were 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 Tax	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	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, 2023
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 2023 2023 2022 L&S Andeavor Logistics Rio Pipeline LLC X 67% $ 171 $ 177 Illinois Extension Pipeline Company, L.L.C. 35% 228 236 LOOP LLC 41% 314 287 MarEn Bakken Company LLC (1) 25% 449 475 Minnesota Pipe Line Company, LLC 17% 174 178 Whistler Pipeline LLC 38% 214 211 Other (2) X 282 269 Total L&S 1,832 1,833 G&P Centrahoma Processing LLC 40% 114 131 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. X 67% 336 335 MarkWest Torñado GP, L.L.C. (3) 100% — 306 MarkWest Utica EMG, L.L.C. X 58% 676 669 Rendezvous Gas Services, L.L.C. X 78% 129 137 Sherwood Midstream Holdings LLC X 51% 113 125 Sherwood Midstream LLC X 50% 500 512 Other (2) X 43 47 Total G&P 1,911 2,262 Total $ 3,743 $ 4,095 (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”). (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, 2023, 2022 and 2021 is as follows: 2023 (In millions) VIEs Non-VIEs Total Revenues and other income $ 806 $ 2,456 $ 3,262 Costs and expenses 336 995 1,331 Income from operations 470 1,460 1,930 Net income 437 1,197 1,634 Income from equity method investments $ 238 $ 362 $ 600 2022 (In millions) 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 2021 (In millions) 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 Summarized balance sheet information for MPLX’s equity method investments as of December 31, 2023 and 2022 is as follows: December 31, 2023 (In millions) VIEs Non-VIEs Total Current assets $ 148 $ 1,383 $ 1,531 Noncurrent assets 3,757 10,103 13,860 Current liabilities 80 899 979 Noncurrent liabilities $ 559 $ 4,297 $ 4,856 December 31, 2022 (In millions) 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

Related Party Agreements and _2

Related Party Agreements and Transactions (Tables)	12 Months Ended
	Dec. 31, 2023
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; and 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 agreements. 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 marine transportation agreements with initial terms of five • 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 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 Agreement with MPC MPLX has an 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 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 bear interest at 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. There was no activity on the MPC Loan Agreement for the year ended December 31, 2023. Activity on the MPC Loan Agreement for the years ended December 31, 2022 and 2021 was as follows: (In millions, except %) 2022 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 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 and other related parties 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, 2023, 2022 and 2021, these sales totaled $739 million, $1,002 million and $811 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. For the years ended December 31, 2023, 2022 and 2021, General and administrative expenses incurred from MPC totaled $262 million, $235 million and $250 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 2023, 2022 and 2021, these charges totaled $94 million, $70 million and $55 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) 2023 2022 Current assets - related parties Receivables $ 587 $ 610 Lease receivables 149 111 Prepaid 5 5 Other 7 3 Total 748 729 Noncurrent assets - related parties Long-term lease receivables 789 883 Right of use assets 227 228 Unguaranteed residual asset 126 87 Long-term receivables 19 27 Total 1,161 1,225 Current liabilities - related parties MPC loan agreement and other payables (1) 278 262 Deferred revenue 81 80 Operating lease liabilities 1 1 Total 360 343 Long-term liabilities - related parties Long-term operating lease liabilities 226 228 Long-term deferred revenue 99 110 Total $ 325 $ 338 (1) There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2023 or 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.
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 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 bear interest at 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. There was no activity on the MPC Loan Agreement for the year ended December 31, 2023. Activity on the MPC Loan Agreement for the years ended December 31, 2022 and 2021 was as follows: (In millions, except %) 2022 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
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) 2023 2022 Current assets - related parties Receivables $ 587 $ 610 Lease receivables 149 111 Prepaid 5 5 Other 7 3 Total 748 729 Noncurrent assets - related parties Long-term lease receivables 789 883 Right of use assets 227 228 Unguaranteed residual asset 126 87 Long-term receivables 19 27 Total 1,161 1,225 Current liabilities - related parties MPC loan agreement and other payables (1) 278 262 Deferred revenue 81 80 Operating lease liabilities 1 1 Total 360 343 Long-term liabilities - related parties Long-term operating lease liabilities 226 228 Long-term deferred revenue 99 110 Total $ 325 $ 338 (1) There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2023 or December 31, 2022.

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2021, 2022, and 2023: (In units) Total Common Units 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 Unit-based compensation awards 196,428 Conversion of Series A preferred units 2,281,831 Balance at December 31, 2023 1,003,498,875
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, 2023, 2022 and 2021: (In millions, except per unit data) 2023 2022 2021 Number of units repurchased — 15 23 Cash paid for units repurchased (1) $ — $ 491 $ 630 Average cost per unit (1) $ — $ 31.96 $ 27.52 (1) Cash paid for common units repurchased and average cost per unit includes commissions paid to brokers during the period. As of December 31, 2023, we had $846 million available under our remaining unit repurchase authorization.
Dividends Declared	Total distributions for the years ended December 31, 2023, 2022 and 2021 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. 2023 2022 2021 Distributions per common unit $ 3.25 $ 2.96 $ 3.36
Distributions Made to Limited Partner, by Distribution [Table Text Block]	The allocation of total quarterly cash distributions to limited, and preferred unitholders is as follows for the years ended December 31, 2023, 2022 and 2021. 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) 2023 2022 2021 Common and preferred unit distributions: Common unitholders, includes common units of general partner (1) $ 3,256 $ 2,980 $ 3,432 Series A preferred unit distributions (1) 94 88 100 Series B preferred unit distributions (2) 5 41 41 Total cash distributions declared $ 3,355 $ 3,109 $ 3,573 (1) 2021 period includes the Supplemental Distribution Amount. (2) 2023 period includes the portion of the $21 million distribution paid to the Series B preferred unitholders on February 15, 2023 that was earned during the period prior to the redemption.

Net Income (Loss) Per Limited_2

Net Income (Loss) Per Limited Partner Unit (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Distributions By Partner By Class [Table Text Block]	(In millions) 2023 2022 2021 Net income attributable to MPLX LP (1) $ 3,928 $ 3,944 $ 3,077 Less: Distributions declared on Series A preferred units (2) 94 88 100 Distributions declared on Series B preferred units 5 41 41 Limited partners’ distributions declared on MPLX common units (including common units of general partner) (2) 3,256 2,980 3,432 Undistributed net income/(loss) attributable to MPLX LP $ 573 $ 835 $ (496) (1) The year ended December 31, 2022 includes a $509 million 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]	2023 (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 $ 3,256 $ 94 $ 5 $ 3,355 Undistributed net income attributable to MPLX LP 557 16 — 573 Net income attributable to MPLX LP (1) $ 3,813 $ 110 $ 5 $ 3,928 Impact of redemption of Series B preferred units (5) (5) Income available to common unitholders $ 3,808 $ 3,923 Weighted average units outstanding: Basic 1,001 Diluted 1,002 Net income attributable to MPLX LP per limited partner unit: Basic $ 3.80 Diluted $ 3.80 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) Includes a $509 million 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 loss attributable to MPLX LP per unit: Net income attributable to MPLX LP: Distribution 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.

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	The tables below present information about revenues and other income, Segment Adjusted EBITDA, capital expenditures and investments in unconsolidated affiliates for our reportable segments: (In millions) 2023 2022 2021 L&S Service revenue $ 4,335 $ 4,057 $ 3,918 Rental income 857 803 772 Product related revenue 18 19 14 Sales-type lease revenue 500 465 435 Income from equity method investments 345 267 153 Other income 68 57 61 Total segment revenues and other income (1) 6,123 5,668 5,353 Segment Adjusted EBITDA (2) 4,228 3,818 3,681 Capital expenditures 414 325 316 Investments in unconsolidated affiliates 26 97 33 G&P Service revenue 2,189 2,056 2,023 Rental income 208 287 347 Product related revenue 2,191 2,792 2,066 Sales-type lease revenue 136 62 — Income from equity method investments 255 209 168 Other income (3) 179 539 70 Total segment revenues and other income (1) 5,158 5,945 4,674 Segment Adjusted EBITDA (2) 2,041 1,957 1,879 Capital expenditures 605 528 224 Investments in unconsolidated affiliates $ 72 $ 120 $ 118 (1) Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $776 million, $644 million and $503 million for the years ended December 31, 2023, 2022 and 2021, respectively. Third party revenues for the G&P segment were $4,827 million, $5,678 million and $4,463 million for the years ended December 31, 2023, 2022 and 2021, respectively. (2) See below for the reconciliation from Segment Adjusted EBITDA to Net income. (3) Includes a $92 million gain on remeasurement of our existing equity investment in Torñado in conjunction with the purchase of the remaining joint venture interest in 2023. Includes a $509 million 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 and Segment Adjusted EBITDA. (In millions) 2023 2022 2021 Reconciliation to Net income: L&S Segment Adjusted EBITDA $ 4,228 $ 3,818 $ 3,681 G&P Segment Adjusted EBITDA 2,041 1,957 1,879 Total reportable segments 6,269 5,775 5,560 Depreciation and amortization (1) (1,213) (1,230) (1,287) Interest and other financial costs (923) (925) (879) Income from equity method investments 600 476 321 Distributions/adjustments related to equity method investments (774) (652) (537) Gain on sales-type leases and equity method investments 92 509 — Impairment expense — — (42) Adjusted EBITDA attributable to noncontrolling interests 42 38 39 Garyville incident response costs (2) (16) — — Other (3) (111) (13) (63) Net income $ 3,966 $ 3,978 $ 3,112 (1) Depreciation and amortization attributable to L&S was $530 million, $515 million and $546 million for the years ended December 31, 2023, 2022 and 2021, respectively. Depreciation and amortization attributable to G&P was $683 million, $715 million and $741 million for the years ended December 31, 2023, 2022 and 2021, respectively. (2) In August 2023, a naphtha release and resulting fire occurred at our Garyville Tank Farm resulting in the loss of four storage tanks with a combined shell capacity of 894 thousand barrels. We incurred $16 million of incident response costs, net of insurance recoveries, during the year ended December 31, 2023. (3) Includes unrealized derivative gain/(loss), equity-based compensation, provision for income taxes, and other miscellaneous items.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2023
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consist of the following: December 31, (In millions) 2023 2022 NGLs $ 8 $ 6 Line fill 15 16 Spare parts, materials and supplies 136 126 Total inventories $ 159 $ 148

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2023
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) 2023 2022 L&S Pipelines 15 - 50 years $ 6,455 $ 6,323 Refining logistics 15 - 20 years 1,818 1,710 Terminals 15 - 40 years 1,651 1,618 Marine 15 - 20 years 1,100 1,000 Land, building and other 5 - 60 years 1,609 1,585 Construction-in-progress 146 180 Total L&S property, plant and equipment 12,779 12,416 G&P Gathering and transportation 5 - 40 years 7,484 6,781 Processing and fractionation 10 - 40 years 6,203 5,928 Land, building and other 5 - 40 years 525 511 Construction-in-progress 394 275 Total G&P property, plant and equipment 14,606 13,495 Total property, plant and equipment 27,385 25,911 Less accumulated depreciation 8,121 7,063 Property, plant and equipment, net $ 19,264 $ 18,848

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2021 $ 7,657 $ 3,141 $ 10,798 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2021 7,657 — 7,657 Disposal of assets (12) — (12) Balance as of December 31, 2022 7,645 — 7,645 Balance as of December 31, 2023 7,645 — 7,645 Gross goodwill as of December 31, 2023 7,645 3,141 10,786 Accumulated impairment losses — (3,141) (3,141) Balance as of December 31, 2023 $ 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, 2023 and 2022 is shown below: December 31, 2023 December 31, 2022 (In millions) Gross Accumulated Amortization (1) Net Gross Accumulated Amortization (1) Net L&S $ 283 $ (189) $ 94 $ 283 $ (153) $ 130 G&P 1,365 (805) 560 1,288 (713) 575 $ 1,648 $ (994) $ 654 $ 1,571 $ (866) $ 705 (1) Amortization expense attributable to the L&S segment for both years ended December 31, 2023 and 2022 was $36 million. Amortization expense attributable to the G&P segment for the years ended December 31, 2023 and 2022 was $92 million and $90 million, respectively.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated future amortization expense related to the intangible assets at December 31, 2023 is as follows: (In millions) 2024 $ 134 2025 121 2026 112 2027 84 2028 67 2029 and thereafter 136 Total $ 654

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	The following table presents the impact on the Consolidated Balance Sheets of MPLX’s financial instruments carried at fair value on a recurring basis as of December 31, 2023 and 2022 by fair value hierarchy level. December 31, 2023 2022 (In millions) Asset Liability Asset Liability Embedded derivatives in commodity contracts (Level 3) Other current assets / Other current liabilities $ — $ 11 $ — $ 10 Other noncurrent assets / Other long-term liabilities — 50 — 51 Total carrying value in Consolidated Balance Sheets $ — $ 61 $ — $ 61
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) 2023 2022 Beginning balance $ (61) $ (108) Unrealized and realized (loss)/gain included in Net Income (1) (11) 35 Settlements 11 12 Ending balance (61) (61) The amount of total (loss)/gain for the period included in earnings attributable to the change in unrealized gain relating to liabilities still held at end of period $ (9) $ 33 (1) (Loss)/gain on derivatives embedded in commodity contracts are recorded in Purchased product costs
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, 2023 2022 (In millions) Fair Value Carrying Value Fair Value Carrying Value Outstanding debt (1) $ 19,377 $ 20,547 $ 18,095 $ 19,905 (1) Any 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, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Gain (Loss) [Table Text Block]	The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized in the Consolidated Statements of Income is summarized below: (In millions) 2023 2022 2021 Product sales Realized gain $ 7 $ — $ — Product sales derivative gain 7 — — Purchased product costs Realized loss (11) (12) (14) Unrealized gain/(loss) — 47 (45) Purchased product cost derivative (loss)/gain (11) 35 (59) Total derivative (loss)/gain included in Net Income $ (4) $ 35 $ (59)

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	MPLX’s outstanding borrowings at December 31, 2023 and 2022 consisted of the following: December 31, (In millions) 2023 2022 MPLX LP: Bank revolving credit facility $ — $ — 4.500% senior notes due July 15, 2023 — 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 1,000 5.000% senior notes due March 1, 2033 1,100 — 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 1,500 5.650% senior notes due March 1, 2053 500 — 4.900% senior notes due April 15, 2058 500 500 Consolidated subsidiaries: MarkWest - 4.500% - 4.875% senior notes, due 2023-2025 12 23 ANDX - 4.250% - 5.200% senior notes, due 2027-2047 31 31 Financing lease obligations (1) 6 8 Total 20,706 20,108 Unamortized debt issuance costs (122) (117) Unamortized discount (153) (195) Amounts due within one year (1,135) (988) Total long-term debt due after one year $ 19,296 $ 18,808 (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, 2023: (In millions) 2024 $ 1,151 2025 1,701 2026 1,501 2027 2,001 2028 $ 1,250
Schedule of Long-term Debt Instruments [Table Text Block]	Activity on the MPLX Credit Agreement was as follows: December 31, (In millions, except %) 2023 2022 Borrowings $ — $ 900 Weighted average interest rate of borrowings — % 1.45 % Repayments $ — $ 1,200 Outstanding balance at end of period $ — $ — Letters of credit outstanding $ 0.2 $ 0.2 Total remaining availability on facility $ 2,000 $ 2,000 Percent of borrowing capacity available 100 % 100 %
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 4.875% 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 5.000% senior notes due March 1, 2033 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 5.650% senior notes due March 1, 2053 March 1 st and September 1 st 4.900% senior notes due April 15, 2058 April 15 th and October 15 th

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023, 2022 and 2021: 2023 (In millions) L&S G&P Total Revenues and other income: Service revenue $ 369 $ 2,170 $ 2,539 Service revenue - related parties 3,966 19 3,985 Service revenue - product related — 294 294 Product sales 5 1,660 1,665 Product sales - related parties 13 237 250 Total revenues from contracts with customers $ 4,353 $ 4,380 8,733 Non-ASC 606 revenue (1) 2,548 Total revenues and other income $ 11,281 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
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, 2023 and 2022: (In millions) Balance at Additions/ (Deletions) Revenue Recognized (1) Balance at Contract assets $ 21 $ (18) $ — $ 3 Long-term contract assets 1 — — 1 Deferred revenue 57 42 (40) 59 Deferred revenue - related parties 63 86 (102) 47 Long-term deferred revenue 216 128 — 344 Long-term deferred revenue - related parties 25 4 — 29 Long-term contract liabilities $ 2 $ (2) $ — $ — (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
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) as of December 31, 2023. The amounts presented below are generally limited to fixed consideration from contracts with customers that contain minimum volume commitments. A significant portion of our future contracted revenue is excluded from the amounts presented below in accordance with ASC 606. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded from this disclosure. Additionally, we do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less, or that are terminable by our customer with little or no termination penalties. Potential future performance obligations related to renewals that have not yet been exercised or are not certain of exercise are excluded from the amounts presented below. Revenues classified as Rental income and Sales-type lease revenue are also excluded from this table. (In billions) 2024 $ 2.0 2025 1.9 2026 1.8 2027 1.7 2028 0.5 2029 and thereafter 0.6 Total revenue on remaining performance obligations $ 8.5 As of December 31, 2023, unsatisfied performance obligations included in the Consolidated Balance Sheets are $479 million and will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 20 years. A portion of this amount is not disclosed in the table above as it is deemed variable consideration due to volume variability.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2023
Supplemental Cash Flow Information [Abstract]
Summary of Supplemental Cash Flow Information	(In millions) 2023 2022 2021 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 893 $ 813 $ 812 Income taxes paid 7 3 4 Cash paid for amounts included in the measurement of lease liabilities: Payments on operating leases 71 73 79 Net cash provided by financing activities included: Principal payments under finance lease obligations 1 2 2 Non-cash investing and financing activities: Net transfers of property, plant and equipment (to)/from materials and supplies inventories (8) (1) 1 ROU assets obtained in exchange for new operating lease obligations 21 78 20 ROU assets obtained in exchange for new finance lease obligations — 1 — Book value of equity method investment (1) 311 — — (1) Represents the book value of MPLX’s equity method investment in Torñado prior to MPLX buying out the remaining interest in this entity. See Note 4 for additional information.
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) 2023 2022 2021 Additions to property, plant and equipment $ 937 $ 806 $ 529 Increase in capital accruals 82 47 11 Total capital expenditures $ 1,019 $ 853 $ 540

Leases Disclosure (Tables)

Leases Disclosure (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Lease, Cost [Table Text Block]	The components of lease cost were as follows: 2023 2022 2021 (In millions) Related Party Third Related Third Related Third Components of lease costs: Operating lease costs $ 14 $ 56 $ 15 $ 61 $ 15 $ 71 Finance lease cost: Amortization of ROU assets — 1 — 1 — 2 Interest on lease liabilities — — — 1 — 1 Total finance lease cost — 1 — 2 — 3 Variable lease cost 4 10 2 16 — 15 Short-term lease cost 1 61 — 45 — 31 Total lease cost $ 19 $ 128 $ 17 $ 124 $ 15 $ 120
Supplemental Balance Sheet Disclosures [Text Block]	Supplemental balance sheet data related to leases were as follows: December 31, 2023 December 31, 2022 (In millions, except % and years) Related Party Third Party Related Party Third Party Operating leases Assets Right of use assets $ 227 $ 264 $ 228 $ 283 Liabilities Operating lease liabilities 1 45 1 46 Long-term operating lease liabilities 226 211 228 230 Total operating lease liabilities $ 227 $ 256 $ 229 $ 276 Weighted average remaining lease term 43 years 9 years 44 years 9 years Weighted average discount rate 5.8 % 4.2 % 5.8 % 4.1 % Finance leases Assets Property, plant and equipment, gross $ 10 $ 11 Less: Accumulated depreciation 5 4 Property, plant and equipment, net 5 7 Liabilities Long-term debt due within one year 1 1 Long-term debt 5 7 Total finance lease liabilities $ 6 $ 8 Weighted average remaining lease term 20 years 18 years Weighted average discount rate 6.0 % 6.0 %
Lessee, Operating Lease, Liability, to be Paid, Maturity	As of December 31, 2023, 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 2024 $ 15 $ 55 $ 1 2025 14 40 1 2026 14 35 1 2027 14 31 1 2028 14 29 1 2029 and thereafter 547 115 6 Gross lease payments 618 305 11 Less: Imputed interest 391 49 5 Total lease liabilities $ 227 $ 256 $ 6
Finance Lease, Liability, to be Paid, Maturity	As of December 31, 2023, 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 2024 $ 15 $ 55 $ 1 2025 14 40 1 2026 14 35 1 2027 14 31 1 2028 14 29 1 2029 and thereafter 547 115 6 Gross lease payments 618 305 11 Less: Imputed interest 391 49 5 Total lease liabilities $ 227 $ 256 $ 6
Operating Lease, Lease Income [Table Text Block]	Lease revenues included on the Consolidated Statements of Income during 2023, 2022 and 2021 were as follows: 2023 2022 2021 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 822 $ 243 $ 763 $ 327 $ 743 $ 376 Sales-type leases: Interest income (Sales-type rental revenue - fixed minimum) 467 114 447 46 431 — Interest income (Revenue from variable lease payments) 33 22 18 16 4 — Sales-type lease revenue $ 500 $ 136 $ 465 $ 62 $ 435 $ —
Sales-type Lease, Lease Income [Table Text Block]	Lease revenues included on the Consolidated Statements of Income during 2023, 2022 and 2021 were as follows: 2023 2022 2021 (In millions) Related Party Third Related Party Third Related Party Third Operating leases: Rental income $ 822 $ 243 $ 763 $ 327 $ 743 $ 376 Sales-type leases: Interest income (Sales-type rental revenue - fixed minimum) 467 114 447 46 431 — Interest income (Revenue from variable lease payments) 33 22 18 16 4 — Sales-type lease revenue $ 500 $ 136 $ 465 $ 62 $ 435 $ —
Lessor, Operating Lease, Payment to be Received, Fiscal Year Maturity [Table Text Block]	The following is a schedule of minimum future rental payments on the non-cancellable operating leases as of December 31, 2023: (In millions) Related Party Third Party Total 2024 $ 759 $ 117 $ 876 2025 737 95 832 2026 590 75 665 2027 447 53 500 2028 168 46 214 2029 and thereafter 47 250 297 Total minimum future rentals $ 2,748 $ 636 $ 3,384
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, 2023: (In millions) Related Party Third Party Total 2024 $ 503 $ 175 $ 678 2025 504 161 665 2026 472 150 622 2027 359 141 500 2028 86 132 218 2029 and thereafter 128 959 1,087 Total minimum future rentals 2,052 1,718 3,770 Less: Imputed interest 1,114 778 1,892 Lease receivable (1) $ 938 940 1,878 Current lease receivables (2) 149 102 251 Long-term lease receivables (3) 789 838 1,627 Unguaranteed residual assets (3) 126 78 204 Total sales-type lease assets $ 1,064 $ 1,018 $ 2,082 (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, 2023 and 2022: December 31, (In millions) 2023 2022 Pipelines $ 677 $ 670 Refining logistics 1,399 1,310 Terminals 1,267 1,241 Marine 126 126 Gathering and transportation 86 94 Processing and fractionation 1,000 973 Land, building and other 165 163 Total property, plant and equipment 4,720 4,577 Less: accumulated depreciation 2,124 1,880 Property, plant and equipment, net $ 2,596 $ 2,697

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule	MPLX executed various third-party transportation, terminalling, and gathering and processing agreements that obligate us to minimum volume, throughput or payment commitments over the remaining terms, which range from less than one year to eight years. After the minimum volume commitments are met in these agreements, MPLX pays additional amounts based on throughput. These agreements may include escalation clauses based on various inflationary indices; however, those potential increases have not been incorporated in minimum fees due under these agreements presented below. The minimum future payments under these agreements as of December 31, 2023 are as follows: (In millions) 2024 $ 187 2025 157 2026 145 2027 130 2028 120 2029 and thereafter 94 Total $ 833

Description of Business and B_3

Description of Business and Basis of Presentation (Details)			12 Months Ended
	Oct. 31, 2012	Mar. 27, 2012	Dec. 31, 2023
Limited Liability Company or Limited Partnership, Business Organization and Operations [Abstract]
Date of partnership formation		Mar. 27, 2012
Date for initial public offering completed	Oct. 31, 2012
Number of reportable segments			2

Summary of Principal Accounti_3

Summary of Principal Accounting Policies (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Asset Retirement Obligation	$ 39	$ 34

Tornado Acquisition (Details)

Tornado Acquisition (Details) - USD ($) $ in Millions	Dec. 15, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Contract with Customer, Asset, Noncurrent		$ 1	$ 1	$ 2
Equity method investments		$ 3,743	$ 4,095
MarkWest Tornado GP, L.L.C.
Business Acquisition [Line Items]
Payments to Acquire Additional Interest in Subsidiaries	$ 303
Payments to Acquire Businesses, Gross	270
Contract with Customer, Asset, Noncurrent	$ 33
Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage	100%
Equity Method Investment, Remaining Ownership Interest Purchased	40%
Equity Interest in Acquiree, Percentage	60%
Equity method investments	$ 311
Equity Interest in Acquiree, Remeasurement Gain	92
Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	673
Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	583
Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	77
Recognized Identifiable Assets Acquired and Liabilities Assumed, Working Capital, Net	30
Recognized Identifiable Other Long-term Assets Acquired and Liabilities Assumed, Net	$ (17)

Javelina Disposition (Details)

Javelina Disposition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Gain (Loss) on Disposition of Assets	$ 14	$ (34)	$ 13
Sale of Javelina Assets and Liabilities
Business Acquisition [Line Items]
Gain (Loss) on Disposition of Assets			$ 0

Investments and Noncontrollin_3

Investments and Noncontrolling Interest (Equity Method Investments) (Details) - USD ($) $ in Millions		Dec. 31, 2023		Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 3,743		$ 4,095
Sherwood Midstream Holdings LLC | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage		24.55%
Logistics and Storage [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 1,832		1,833
Logistics and Storage [Member] | Andeavor Logistics Rio Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		67%
Equity method investments		$ 171		177
Logistics and Storage [Member] | Illinois Extension Pipeline Company, L.L.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage		35%
Equity method investments		$ 228		236
Logistics and Storage [Member] | LOOP LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		41%
Equity method investments		$ 314		287
Logistics and Storage [Member] | MarEn Bakken Company LLC(1)
Schedule of Equity Method Investments [Line Items]
Ownership percentage	[1]	25%
Equity method investments	[1]	$ 449		475
Logistics and Storage [Member] | Minnesota Pipe Line Company, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		17%
Equity method investments		$ 174		178
Logistics and Storage [Member] | Whistler Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		38%
Equity method investments		$ 214		211
Logistics and Storage [Member] | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	$ 282		269
Logistics and Storage [Member] | Bakken Pipeline System | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage		9.19%
Gathering and Processing [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 1,911		2,262
Gathering and Processing [Member] | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	$ 43		47
Gathering and Processing [Member] | Centrahoma Processing LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		40%
Equity method investments		$ 114		131
Gathering and Processing [Member] | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage		67%
Equity method investments		$ 336		$ 335
Gathering and Processing [Member] | MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage		100%	[3]	60%
Equity method investments	[3]	$ 0		$ 306
Gathering and Processing [Member] | MarkWest Utica EMG, L.L.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage		58%
Equity method investments		$ 676		669
Gathering and Processing [Member] | Rendezvous Gas Services, L.L.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage		78%
Equity method investments		$ 129		137
Gathering and Processing [Member] | Sherwood Midstream Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 113		125
Gathering and Processing [Member] | Sherwood Midstream Holdings LLC | Direct Ownership Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage		51%
Gathering and Processing [Member] | Sherwood Midstream LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage		50%
Equity method investments		$ 500		$ 512
[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”).[2]Some investments included within Other have also been deemed to be VIEs.[3]At December 31, 2022, we owned a 60 percent interest in Torñado. On December 15, 2023, we acquired the remaining 40 percent interest. As a result of acquiring the remaining interest, we obtained control of and now consolidate Torñado.

Investments and Noncontrollin_4

Investments and Noncontrolling Interests (Summary of Equity Method Investment Financial Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Revenues and other income	$ 11,281	$ 11,613	$ 10,027
Costs and expenses	6,381	6,702	6,035
Net income	3,966	3,978	3,112
Income from equity method investments	600	476	321
Current assets	2,808	1,905
Current liabilities	2,624	2,401
VIEs
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	238	275	175
Non-VIEs
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	362	201	146
Non-VIEs
Schedule of Equity Method Investments [Line Items]
Revenues and other income	2,456	1,456	1,236
Costs and expenses	995	648	568
Income from operations	1,460	808	668
Net income	1,197	711	594
Current assets	1,383	450
Noncurrent assets	10,103	5,225
Current liabilities	899	181
Noncurrent liabilities	4,297	876
VIEs
Schedule of Equity Method Investments [Line Items]
Revenues and other income	806	1,197	820
Costs and expenses	336	603	490
Income from operations	470	594	330
Net income	437	535	266
Current assets	148	474
Noncurrent assets	3,757	7,721
Current liabilities	80	323
Noncurrent liabilities	559	2,546
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Revenues and other income	3,262	2,653	2,056
Costs and expenses	1,331	1,251	1,058
Income from operations	1,930	1,402	998
Net income	1,634	1,246	$ 860
Current assets	1,531	924
Noncurrent assets	13,860	12,946
Current liabilities	979	504
Noncurrent liabilities	$ 4,856	$ 3,422

Investments and Noncontrollin_5

Investments and Noncontrolling Interests (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Sherwood Midstream Holdings LLC | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage	24.55%
Gathering and Processing [Member]
Schedule of Equity Method Investments [Line Items]
Basis difference	$ (45)	$ (51)
Basis difference, not amortized	31	31
Logistics and Storage [Member]
Schedule of Equity Method Investments [Line Items]
Basis difference	314	320
Basis difference, not amortized	$ 167	$ 167
Logistics and Storage [Member] | Bakken Pipeline System | Indirect Ownership Interest
Schedule of Equity Method Investments [Line Items]
Ownership percentage	9.19%

Related Party Agreements and _3

Related Party Agreements and Transactions (Narrative) (Detail) - Related Party	12 Months Ended
	Dec. 31, 2023
Fuels Distribution [Member]
Related Party Transaction [Line Items]
Term Of Agreements	10 years
Renewal Term Agreement	5 years
Marine Services Equipment [Member]
Related Party Transaction [Line Items]
Renewal Term Agreement	5 years
Number of renewals	1
Co-location Agreements [Member]
Related Party Transaction [Line Items]
Term Of Agreements	50 years
Marine Management Services [Member]
Related Party Transaction [Line Items]
Term Of Agreements	5 years
Renewal Term Agreement	5 years
Number of renewals	1
Minimum | Marine Services Equipment [Member]
Related Party Transaction [Line Items]
Term Of Agreements	5 years
Maximum | Marine Services Equipment [Member]
Related Party Transaction [Line Items]
Term Of Agreements	6 years
Operating Agreements [Member] | Minimum
Related Party Transaction [Line Items]
Term Of Agreements	1 year
Operating Agreements [Member] | Maximum
Related Party Transaction [Line Items]
Term Of Agreements	10 years

Related Party Agreements and _4

Related Party Agreements and Transactions (Intercompany Loans with Related Parties) (Detail) - Revolving Credit Facility - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Repayments of Related Party Debt	$ 0	$ 4,439	$ 7,043
Proceeds from Related Party Debt	0	$ 2,989	$ 8,493
Related Party
Related Party Transaction [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,500
Debt Instrument, Description of Variable Rate Basis	one-month term SOFR adjusted upward by 0.10 percent plus 1.25 percent
Interest rate during period		1.50%	1.34%
Line of Credit, Current	$ 0	$ 0	$ 1,450

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, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party
Related Party Transaction [Line Items]
Sales Revenue, Goods, Related Party, Net Zero	$ 739	$ 1,002	$ 811

Related Party Agreements and _6

Related Party Agreements and Transactions (Summary of Expenses by Income Statement RP Line Item) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
General and administrative expenses	$ 379	$ 335	$ 353
Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
General and administrative expenses	262	235	250
Construction-in-progress | Marathon Petroleum Corporation [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 94	$ 70	$ 55

Related Party Agreements and _7

Related Party Agreements and Transactions (Summary of Balance Sheet by RP Line Item) (Details) - USD ($) $ in Millions		Dec. 31, 2023		Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Receivables, net		$ 823		$ 737
Lease receivables	[1]	251
Other current assets		30		53
Long-term lease receivables	[2]	1,627
Long-term lease receivables		264		283
Unguaranteed residual asset	[2]	204
Deferred Revenue, Noncurrent		347		219
Related Party
Related Party Transaction [Line Items]
Receivables, net		587		610
Lease receivables		149	[1]	111
Prepaid		5		5
Other current assets		7		3
Due from Related Parties, Current		748		729
Long-term lease receivables		789	[2]	883
Long-term lease receivables		227		228
Unguaranteed residual asset		126	[2]	87
Long-term receivables		19		27
Other Receivable, after Allowance for Credit Loss, Noncurrent		1,161		1,225
MPC loan agreement and other payables(1)	[3]	278		262
Deferred revenue		81		80
Operating lease liabilities		1		1
Other Liabilities, Current		360		343
Long-term operating lease liabilities		226		228
Deferred Revenue, Noncurrent		99		110
Other Liabilities, Noncurrent		325		338
Related Party | Revolving Credit Facility
Related Party Transaction [Line Items]
Line of Credit, Current		$ 0		$ 0	$ 1,450
[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] There were no borrowings outstanding on the MPC Loan Agreement as of December 31, 2023 or December 31, 2022.

Equity (Changes in Partners Cap

Equity (Changes in Partners Capital, Unit Rollforward) (Details) - shares	12 Months Ended			36 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2020
Stockholders Equity [Line Items]
Units outstanding	1,003,498,875	1,001,020,616	1,016,178,378	1,003,498,875	1,038,777,978
Unit-based compensation awards	196,428	190,529	214,466
Conversion of Series A preferred units	2,281,831		93,108	2,400,000
Units redeemed in unit repurchase program	0	(15,348,291)	(22,907,174)
Related Party
Stockholders Equity [Line Items]
Units outstanding	647,415,452			647,415,452

Repurchase Program (Details)

Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Aug. 02, 2022	Nov. 02, 2020
Equity, Class of Treasury Stock [Line Items]
Authorized Amount					$ 1,000	$ 1,000
Number of units repurchased		0	15,348,291	22,907,174
Cash Paid for Units Repurchased	[1]	$ 0	$ 491	$ 630
Average cost per unit(1)	[1]	$ 0	$ 31.96	$ 27.52
Remaining Authorized Repurchase Amount		$ 846
[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, 2024	Feb. 05, 2024	Jan. 24, 2024	Feb. 15, 2023	Oct. 26, 2021	Dec. 31, 2023		Dec. 31, 2022	Dec. 31, 2021
Distribution Made to Limited Partner [Line Items]
Cash Distributions Declared						$ 3,355		$ 3,109	$ 3,573
Distributions Declared, Per Unit						$ 3.25		$ 2.96	$ 3.36	[1]
Special Distribution
Distribution Made to Limited Partner [Line Items]
Distributions Declared, Per Unit					$ 0.575
Common Stock [Member]
Distribution Made to Limited Partner [Line Items]
Cash Distributions Declared						$ 3,256		$ 2,980	$ 3,432	[1]
Series A Preferred Stock [Member]
Distribution Made to Limited Partner [Line Items]
Cash Distributions Declared						94		88	100	[1]
Series B Preferred Stock [Member]
Distribution Made to Limited Partner [Line Items]
Cash Distributions Declared						$ 5	[2]	$ 41	$ 41
Distribution date				Feb. 15, 2023
Subsequent Event
Distribution Made to Limited Partner [Line Items]
Distribution declaration date			Jan. 24, 2024
Cash Distributions Declared			$ 853
Distributions Declared, Per Unit			$ 0.8500
Subsequent Event | Common Stock [Member]
Distribution Made to Limited Partner [Line Items]
Distribution date	Feb. 14, 2024
Distribution date of record		Feb. 05, 2024
[1]2021 period includes the Supplemental Distribution Amount.[2]2023 period includes the portion of the $21 million distribution paid to the Series B preferred unitholders on February 15, 2023 that was earned during the period prior to the redemption.

Series A Preferred Units (Detai

Series A Preferred Units (Details) - shares	12 Months Ended		36 Months Ended
	Dec. 31, 2023	Dec. 31, 2021	Dec. 31, 2023
Conversion of Series A preferred units	2,281,831	93,108	2,400,000
Common Stock [Member]
Conversion of Series A preferred units	2,281,831	93,108

Series B Preferred Units (Detai

Series B Preferred Units (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 15, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Partners' Capital Account, Distributions		$ 3,243	$ 3,000	$ 3,512
Series B Preferred Stock [Member]
Preferred Units, Outstanding		0	600,000
Preferred Stock, Dividend Rate, Percentage		6.875%
Preferred Stock, Redemption Price Per Share	$ 1,000
Preferred Stock, Redemption Terms	MPLX exercised its right to redeem all 600,000 units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units (the “Series B preferred units”). MPLX paid unitholders the Series B preferred unit redemption price of $1,000 per unit.
Partners' Capital Account, Distributions	$ 21
Distribution date	Feb. 15, 2023
Partners' Capital Account, Units, Redeemed	600,000

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, 2023		Dec. 31, 2022		Dec. 31, 2021
Net Income Per Share [Line Items]
Net income attributable to MPLX LP(1)	$ 3,928		$ 3,944	[1]	$ 3,077
Cash Distributions Declared	3,355		3,109		3,573
Undistributed net income/(loss) attributable to MPLX LP	573		835		(496)
Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP(1)	110		112	[1]	100
Cash Distributions Declared	94		88		100	[2]
Series B Preferred Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP(1)	5		41	[1]	41
Cash Distributions Declared	5	[3]	41		41
Common Stock [Member]
Net Income Per Share [Line Items]
Net income attributable to MPLX LP(1)	3,813		3,791	[1]	2,936
Cash Distributions Declared	$ 3,256		$ 2,980		$ 3,432	[2]
[1]The year ended December 31, 2022 includes a $509 million gain on a lease reclassification. See Note 20 for additional information.[2]2021 period includes the Supplemental Distribution Amount.[3]2023 period includes the portion of the $21 million distribution paid to the Series B preferred unitholders on February 15, 2023 that was earned during the period prior to the redemption.

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, 2023		Dec. 31, 2022		Dec. 31, 2021
Net income attributable to MPLX LP:
Cash Distributions Declared	$ 3,355		$ 3,109		$ 3,573
Undistributed net income loss attributable to MPLX LP	573		835		(496)
Net income attributable to MPLX LP(1)	3,928		$ 3,944	[1]	$ 3,077
Impact of redemption of Series B preferred units	(5)
Income available to common unitholders	$ 3,923
Weighted average units outstanding:
Basic (shares)	1,001		1,010		1,027
Diluted (shares)	1,002		1,010		1,027
Net income attributable to MPLX LP subsequent to initial public offering per limited partner unit:
Basic (in USD per unit)	$ 3.80		$ 3.75		$ 2.86
Diluted (in USD per unit)	$ 3.80		$ 3.75		$ 2.86
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
Common Stock [Member]
Net income attributable to MPLX LP:
Cash Distributions Declared	$ 3,256		2,980		$ 3,432	[2]
Undistributed net income loss attributable to MPLX LP	557		811		(496)
Net income attributable to MPLX LP(1)	3,813		3,791	[1]	2,936
Impact of redemption of Series B preferred units	(5)
Income available to common unitholders	3,808
Series A Preferred Stock [Member]
Net income attributable to MPLX LP:
Cash Distributions Declared	94		88		100	[2]
Undistributed net income loss attributable to MPLX LP	16		24		0
Net income attributable to MPLX LP(1)	110		112	[1]	100
Series B Preferred Stock [Member]
Net income attributable to MPLX LP:
Cash Distributions Declared	5	[3]	41		41
Undistributed net income loss attributable to MPLX LP	0		0		0
Net income attributable to MPLX LP(1)	$ 5		$ 41	[1]	$ 41
[1]The year ended December 31, 2022 includes a $509 million gain on a lease reclassification. See Note 20 for additional information.[2]2021 period includes the Supplemental Distribution Amount.[3]2023 period includes the portion of the $21 million distribution paid to the Series B preferred unitholders on February 15, 2023 that was earned during the period prior to the redemption.

Redeemable Preferred Units (Nar

Redeemable Preferred Units (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended				36 Months Ended
	Jan. 24, 2024	May 13, 2016	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021		Dec. 31, 2023
Redeemable Noncontrolling Interest [Line Items]
Distributions Declared, Per Unit			$ 3.25	$ 2.96	$ 3.36	[1]
Conversion of Series A preferred units			2,281,831		93,108		2,400,000
Series A Preferred Stock [Member]
Redeemable Noncontrolling Interest [Line Items]
Preferred Stock, Dividend Rate, Percentage		6.50%
Units issued, price per unit		$ 32.50
Proceeds from issuance of preferred units		$ 984
Preferred units, dividend rate, per-dollar-amount		$ 0.528125
Series A preferred, Units Issued		30,800,000
Series A preferred, Units Outstanding			27,200,000	30,000,000			27,200,000
Temporary Equity, 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.
Common Stock [Member]
Redeemable Noncontrolling Interest [Line Items]
Conversion of Series A preferred units			2,281,831		93,108
Subsequent Event
Redeemable Noncontrolling Interest [Line Items]
Distribution declaration date	Jan. 24, 2024
Distributions Declared, Per Unit	$ 0.8500
[1]2021 period includes the Supplemental Distribution Amount.

Segment Information (Details)

Segment Information (Details)	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information - Revenues

Segment Information - Revenues and Adjusted EBITDA (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 8,733		$ 8,924		$ 8,021
Sales-type lease revenue		136		62		0
Income from equity method investments		600		476		321
Capital expenditures		1,019		853		540
Investments in unconsolidated affiliates		(98)		(217)		(151)
Total segment revenues and other income		11,281		11,613		10,027
Nonrelated Party
Segment Reporting, Revenue Reconciling Item [Line Items]
Rental Income		243		327		376
Sales-type lease revenue		136		62		0
Other Income		126		485		21
Sales-type Lease, Selling Profit (Loss)				509	[1]	0
Other Income [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales-type Lease, Selling Profit (Loss)				509
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA		6,269		5,775		5,560
Segment Reconciling Items
Segment Reporting, Revenue Reconciling Item [Line Items]
Income from equity method investments		600		476		321
Logistics and Storage [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,353		4,076		3,932
Logistics and Storage [Member] | Nonrelated Party
Segment Reporting, Revenue Reconciling Item [Line Items]
Total segment revenues and other income		776		644		503
Logistics and Storage [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Rental Income		857		803		772
Sales-type lease revenue		500		465		435
Income from equity method investments		345		267		153
Other Income		68		57		61
Adjusted EBITDA	[2]	4,228		3,818		3,681
Capital expenditures		414		325		316
Investments in unconsolidated affiliates		(26)		(97)		(33)
Total segment revenues and other income	[3]	6,123		5,668		5,353
Gathering and Processing [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,380		4,848		4,089
Gathering and Processing [Member] | Nonrelated Party
Segment Reporting, Revenue Reconciling Item [Line Items]
Total segment revenues and other income		4,827		5,678		4,463
Gathering and Processing [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Rental Income		208		287		347
Sales-type lease revenue		136		62		0
Income from equity method investments		255		209		168
Other Income		179	[4]	539	[4]	70
Adjusted EBITDA	[2]	2,041		1,957		1,879
Capital expenditures		605		528		224
Investments in unconsolidated affiliates		(72)		(120)		(118)
Total segment revenues and other income	[3]	5,158		5,945		4,674
Service [Member] | Logistics and Storage [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,335		4,057		3,918
Service [Member] | Gathering and Processing [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,189		2,056		2,023
Product [Member] | Logistics and Storage [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		18		19		14
Product [Member] | Gathering and Processing [Member] | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 2,191		$ 2,792		$ 2,066
[1]The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income.[2]See below for the reconciliation from Segment Adjusted EBITDA to Net income.[3]Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $776 million, $644 million and $503 million for the years ended December 31, 2023, 2022 and 2021, respectively. Third party revenues for the G&P segment were $4,827 million, $5,678 million and $4,463 million for the years ended December 31, 2023, 2022 and 2021, respectively.[4]Includes a $92 million gain on remeasurement of our existing equity investment in Torñado in conjunction with the purchase of the remaining joint venture interest in 2023. Includes a $509 million 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, 2023		Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Depreciation and amortization		$ 1,213		$ 1,230	$ 1,287
Income from equity method investments		600		476	321
Gain on sales-type leases and equity method investment		92		509	0
Impairment expense		0		0	(42)
Net income		3,966		3,978	3,112
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA		6,269		5,775	5,560
Operating Segments | Logistics and Storage [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA	[1]	4,228		3,818	3,681
Depreciation and amortization		530		515	546
Income from equity method investments		345		267	153
Operating Segments | Gathering and Processing [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA	[1]	2,041		1,957	1,879
Depreciation and amortization		683		715	741
Income from equity method investments		255		209	168
Segment Reconciling Items
Segment Reporting Information [Line Items]
Depreciation and amortization	[2]	1,213		1,230	1,287
Interest and Other Financial Costs		923		925	879
Income from equity method investments		600		476	321
Distributions/adjustments related to equity method investments		774		652	537
Gain on sales-type leases and equity method investment		92		509	0
Impairment expense		0		0	(42)
Adjusted EBITDA attributable to noncontrolling interests		42		38	39
Garyville incident response costs		(16)	[3]	0	0
Other	[4]	$ (111)		$ (13)	$ (63)
[1]See below for the reconciliation from Segment Adjusted EBITDA to Net income.[2]Depreciation and amortization attributable to L&S was $530 million, $515 million and $546 million for the years ended December 31, 2023, 2022 and 2021, respectively. Depreciation and amortization attributable to G&P was $683 million, $715 million and $741 million for the years ended December 31, 2023, 2022 and 2021, respectively.[3]In August 2023, a naphtha release and resulting fire occurred at our Garyville Tank Farm resulting in the loss of four storage tanks with a combined shell capacity of 894 thousand barrels. We incurred $16 million of incident response costs, net of insurance recoveries, during the year ended December 31, 2023.[4]Includes unrealized derivative gain/(loss), equity-based compensation, provision for income taxes, and other miscellaneous items

Major Customers and Concentra_2

Major Customers and Concentration of Credit Risk (Details) - Revenue Benchmark [Member] - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2023		Dec. 31, 2022	[1]	Dec. 31, 2021
Marathon Petroleum Corporation [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	50%		47%		50%
Nonrelated Party
Concentration Risk [Line Items]
Concentration risk, percentage	10%
Logistics and Storage [Member] | Marathon Petroleum Corporation [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	87%	[1]	88%		90%
Gathering and Processing [Member] | Marathon Petroleum Corporation [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	5%		4%		3%
[1]The percent calculations for the year ended December 31, 2023 exclude a $92 million gain associated with the remeasurement of its existing equity investment in Torñado. The percent calculations for the year ended December 31, 2022 exclude a $509 million gain on a lease reclassification.

Inventories (Summary of Invento

Inventories (Summary of Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
NGLs	$ 8	$ 6
Line fill	15	16
Spare parts, materials and supplies	136	126
Total inventories	$ 159	$ 148

Property, Plant and Equipment_2

Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 27,385	$ 25,911
Less accumulated depreciation	8,121	7,063
Property, plant and equipment, net	19,264	18,848
Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,779	12,416
Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14,606	13,495
Pipelines And Related Assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,455	6,323
Refineries and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,818	1,710
Terminals and related assets [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,651	1,618
Barges and towing vessels [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,100	1,000
Land Building Office Equipment And Other [Member] | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,609	1,585
Land Building Office Equipment And Other [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	525	511
Gas Gathering And Transmission Equipment And Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,484	6,781
Processing, Fractionation And Storage Facilities [Member] | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,203	5,928
Construction-in-progress | Logistics and Storage [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	146	180
Construction-in-progress | Gathering and Processing [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 394	$ 275
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

Property Plant and Equipment (N

Property Plant and Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Interest costs capitalized	$ 15	$ 9	$ 14
Asset Impairment Charges	$ 0	$ 0	$ 42

Goodwill and Intangibles (Goodw

Goodwill and Intangibles (Goodwill) (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Nov. 30, 2023	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 0
Number of reporting units with goodwill	3
Goodwill	$ 7,645		$ 7,645	$ 7,657
Total Number of Reporting Units	5
Crude Gathering [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		10%
Gathering and Processing [Member]
Goodwill [Line Items]
Goodwill	$ 0		$ 0	$ 0
Measurement Input, Discount Rate [Member] | Goodwill | Income Approach Valuation Technique
Goodwill [Line Items]
Fair Value Inputs	10.20%

Goodwill and Intangibles (Recon

Goodwill and Intangibles (Reconciliation of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Gross goodwill	$ 10,786		$ 10,798
Goodwill, Impaired, Accumulated Impairment Loss	(3,141)		(3,141)
Goodwill, beginning balance	7,645	$ 7,657
Goodwill, Impairment Loss	0
Goodwill, Written off Related to Sale of Business Unit		(12)
Goodwill, ending balance	7,645	7,645
Logistics and Storage [Member]
Goodwill [Line Items]
Gross goodwill	7,645		7,657
Goodwill, Impaired, Accumulated Impairment Loss	0		0
Goodwill, beginning balance	7,645	7,657
Goodwill, Written off Related to Sale of Business Unit		(12)
Goodwill, ending balance	7,645	7,645
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, Written off Related to Sale of Business Unit		0
Goodwill, ending balance	$ 0	$ 0

Goodwill and Intangibles (Intan

Goodwill and Intangibles (Intangible Assets) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross Intangibles		$ 1,648	$ 1,571
Accumulated amortization	[1]	(994)	(866)
Intangibles, net		654	705
Logistics and Storage [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangibles		283	283
Accumulated amortization	[1]	(189)	(153)
Intangibles, net		94	130
Amortization of Intangible Assets		36	36
Gathering and Processing [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Intangibles		1,365	1,288
Accumulated amortization	[1]	(805)	(713)
Intangibles, net		560	575
Amortization of Intangible Assets		$ 92	$ 90
[1]Amortization expense attributable to the L&S segment for both years ended December 31, 2023 and 2022 was $36 million. Amortization expense attributable to the G&P segment for the years ended December 31, 2023 and 2022 was $92 million and $90 million, respectively.

Goodwill and Intangibles (Futur

Goodwill and Intangibles (Future Amortization Expense) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2024	$ 134
2025	121
2026	112
2027	84
2028	67
2029 and thereafter	136
Total future intangibles amortization expense	$ 654

Fair Value Measurements - Recur

Fair Value Measurements - Recurring (Financial Instruments by Valuation Hierarchy) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Subject to Master Netting Arrangement, before Offset	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	61	61
Fair Value, Inputs, Level 3 [Member] | Other current assets | Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Subject to Master Netting Arrangement, before Offset	0	0
Fair Value, Inputs, Level 3 [Member] | Other noncurrent assets | Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Subject to Master Netting Arrangement, before Offset	0	0
Fair Value, Inputs, Level 3 [Member] | Other current liabilities | Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Gross Liability	11	10
Fair Value, Inputs, Level 3 [Member] | Other Noncurrent Liabilities [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 50	$ 51

Fair Value Measurements - Rec_2

Fair Value Measurements - Recurring (Significant Unobservable Inputs in Level 3 Valuation) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.76
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]
Derivative, Forward Price	0.61
Maximum | Embedded Derivative Financial Instruments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Forward Price	1.44

Fair Value Measurements - Rec_3

Fair Value Measurements - Recurring (Changes in Level 3 Measurements) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		$ (61)	$ (108)
Unrealized and realized Gain (Loss) Included in Net Income	[1]	$ (11)	$ 35
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Cost of Goods and Services Sold	Cost of Goods and Services Sold
Settlements		$ 11	$ 12
Ending balance		(61)	(61)
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)		$ (9)	$ 33
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Cost of Goods and Services Sold	Cost of Goods and Services Sold
[1](Loss)/gain on derivatives embedded in commodity contracts are recorded in Purchased product costs

Fair Value Measurements - Repor

Fair Value Measurements - Reported (Details) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-Term Debt, Fair Value	[1]	$ 19,377	$ 18,095
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-Term Debt, Fair Value	[1]	$ 20,547	$ 19,905
[1]Any 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, 2023 USD ($) gal	Dec. 31, 2022 USD ($)
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 have been aggregated into a single compound embedded derivative.
Propane | Short | Over-the-Counter
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | gal	0
Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Number of renewals	1
Embedded Derivative Renewal Term	5 years
Derivative, Term of Contract	5 years
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Liability | $	$ 61	$ 61

Derivative Financial Instrume_4

Derivative Financial Instruments (Derivatives Income Statement Location) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net income	Net income	Net income
Derivative, Gain (Loss) on Derivative, Net	$ (4)	$ 35	$ (59)
Purchased product costs
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Realized Gain (Loss), Net	(11)	(12)	(14)
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ 0	$ 47	$ (45)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Goods and Services Sold	Cost of Goods and Services Sold	Cost of Goods and Services Sold
Derivative, Gain (Loss) on Derivative, Net	$ (11)	$ 35	$ (59)
Product sales
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Realized Gain (Loss), Net	$ 7	$ 0	$ 0
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Excluding Assessed Tax, Third parties	Revenue from Contract with Customer, Excluding Assessed Tax, Third parties	Revenue from Contract with Customer, Excluding Assessed Tax, Third parties
Derivative, Gain (Loss) on Derivative, Net	$ 7	$ 0	$ 0

Debt (Summary of Outstanding Bo

Debt (Summary of Outstanding Borrowings) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Feb. 15, 2023	Feb. 09, 2023	Dec. 31, 2022	Sep. 15, 2022	Aug. 25, 2022	Aug. 11, 2022	Mar. 14, 2022	Jan. 15, 2021
Debt Instrument [Line Items]
Finance Lease, Liability	[1]	$ 6			$ 8
Debt and capital lease obligations		20,706			20,108
Unamortized debt issuance costs		122			117
Unamortized discount		153			195
Debt, Current		1,135			988
Total long-term debt due after one year		19,296			18,808
MPLX Revolving Credit Facility due July 2027
Debt Instrument [Line Items]
Outstanding balance		0			0
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Outstanding balance					0
Senior Notes | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Interest Rate			4.50%
Senior Notes | Senior Note Due September 2032
Debt Instrument [Line Items]
Interest Rate								4.95%
Senior Notes | Senior Note Due March 2033
Debt Instrument [Line Items]
Interest Rate				5%
Senior Notes | Senior Note Due March 2052 [Member]
Debt Instrument [Line Items]
Interest Rate									4.95%
Senior Notes | Senior Note Due March 2053
Debt Instrument [Line Items]
Interest Rate				5.65%
Senior Notes | Senior Notes Due December 2022 [Member]
Debt Instrument [Line Items]
Interest Rate							3.50%
Senior Notes | Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Interest Rate						3.375%
Senior Notes | Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Interest Rate										5.25%
MPLX LP | Senior Notes | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0			989
Interest Rate		4.50%
Maturity Date		Jul. 15, 2023
MPLX LP | Senior Notes | Senior Notes Due December 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,149			1,149
Interest Rate		4.875%
Maturity Date		Dec. 01, 2024
MPLX LP | Senior Notes | Senior Notes Due February 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 500			500
Interest Rate		4%
Maturity Date		Feb. 15, 2025
MPLX LP | Senior Notes | Senior Notes Due June 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,189			1,189
Interest Rate		4.875%
Maturity Date		Jun. 01, 2025
MPLX LP | Senior Notes | Senior Notes Due March 2026 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Interest Rate		1.75%
Maturity Date		Mar. 01, 2026
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		4.125%
Maturity Date		Mar. 01, 2027
MPLX LP | Senior Notes | Senior Notes Due December 2027 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 732			732
Interest Rate		4.25%
Maturity Date		Dec. 01, 2027
MPLX LP | Senior Notes | Senior Notes Due March 2028 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,250			1,250
Interest Rate		4%
Maturity Date		Mar. 15, 2028
MPLX LP | Senior Notes | Senior Notes Due February 2029 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 750			750
Interest Rate		4.80%
Maturity Date		Feb. 15, 2029
MPLX LP | Senior Notes | Senior Notes Due August 2030 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Interest Rate		2.65%
Maturity Date		Aug. 15, 2030
MPLX LP | Senior Notes | Senior Note Due September 2032
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,000			1,000
Interest Rate		4.95%
Maturity Date		Sep. 01, 2032
MPLX LP | Senior Notes | Senior Note Due March 2033
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,100			0
Interest Rate		5%
Maturity Date		Mar. 01, 2033
MPLX LP | Senior Notes | Senior Notes Due April 2038 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,750			1,750
Interest Rate		4.50%
Maturity Date		Apr. 15, 2038
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		5.20%
Maturity Date		Mar. 01, 2047
MPLX LP | Senior Notes | Senior Notes Due December 2047 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 487			487
Interest Rate		5.20%
Maturity Date		Dec. 01, 2047
MPLX LP | Senior Notes | Senior Notes Due April 2048 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Interest Rate		4.70%
Maturity Date		Apr. 15, 2048
MPLX LP | Senior Notes | Senior Notes Due February 2049 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Interest Rate		5.50%
Maturity Date		Feb. 15, 2049
MPLX LP | Senior Notes | Senior Note Due March 2052 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 1,500			1,500
Interest Rate		4.95%
Maturity Date		Mar. 14, 2052
MPLX LP | Senior Notes | Senior Note Due March 2053
Debt Instrument [Line Items]
Long-term debt, gross		$ 500			0
Interest Rate		5.65%
Maturity Date		Mar. 01, 2053
MPLX LP | Senior Notes | Senior Notes Due April 2058 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 500			500
Interest Rate		4.90%
Maturity Date		Apr. 15, 2058
MarkWest | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross		$ 12			23
MarkWest | Senior Notes | Minimum
Debt Instrument [Line Items]
Interest Rate		4.50%
Maturity Date		Jul. 15, 2023
MarkWest | Senior Notes | Maximum
Debt Instrument [Line Items]
Interest Rate		4.875%
Maturity Date		Jun. 01, 2025
ANDX LP [Member] | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross		$ 31			$ 31
ANDX LP [Member] | Senior Notes | Minimum
Debt Instrument [Line Items]
Interest Rate		4.25%
Maturity Date		Dec. 01, 2027
ANDX LP [Member] | Senior Notes | Maximum
Debt Instrument [Line Items]
Interest Rate		5.20%
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, 2023	Feb. 15, 2023	Dec. 31, 2022	Sep. 15, 2022	Aug. 25, 2022	Aug. 11, 2022	Mar. 14, 2022	Jan. 15, 2021
Senior Note Due September 2032
Debt Instrument [Line Items]
Interest rate, stated percentage						4.95%
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 July 2023 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage		4.50%
Senior Notes Due January 2025 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage								5.25%
Senior Note Due March 2052 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage							4.95%
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 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 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 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 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		1,000
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	$ 0		989
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 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 Note Due March 2052 [Member]
Debt Instrument [Line Items]
Interest rate, stated percentage	4.95%
Debt Instrument, Maturity Date	Mar. 14, 2052
Long-term debt, gross	$ 1,500		1,500
MarkWest
Debt Instrument [Line Items]
Long-term debt, gross	$ 12		23
MarkWest | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Debt Instrument, Maturity Date	Jul. 15, 2023
MarkWest | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.875%
Debt Instrument, Maturity Date	Jun. 01, 2025
ANDX LP [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 31		$ 31
ANDX LP [Member] | Minimum
Debt Instrument [Line Items]
Interest rate, stated percentage	4.25%
Debt Instrument, Maturity Date	Dec. 01, 2027
ANDX LP [Member] | Maximum
Debt Instrument [Line Items]
Interest rate, stated percentage	5.20%
Debt Instrument, Maturity Date	Dec. 01, 2047

Debt (Schedule of Debt Payments

Debt (Schedule of Debt Payments) (Detail) $ in Millions	Dec. 31, 2023 USD ($)
Debt Disclosure [Abstract]
2024	$ 1,151
2025	1,701
2026	1,501
2027	2,001
2028	$ 1,250

Debt (Credit Agreements) (Detai

Debt (Credit Agreements) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Long-term Line of Credit		$ 0
MPLX Revolving Credit Facility due July 2027
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 2,000
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 renewals	2
Debt Instrument, Renewal Term	1 year
Number of prior quarterly reporting periods used in determining compliance with covenant of ratio of consolidated net debt to consolidated EBITDA	4
Proceeds from long-term lines of credit	$ 0	$ 900
Debt, Weighted Average Interest Rate	0%	1.45%
Repayments of long-term lines of credit	$ 0	$ 1,200
Letters of credit outstanding, amount	0.2	0.2
Remaining borrowing capacity	2,000	2,000
Long-term Line of Credit	$ 0	$ 0
Remaining borrowing capacity, percentage	100%	100%
Expiration date	Jul. 07, 2027
MPLX Revolving Credit Facility due July 2027 | Maximum
Debt Instrument [Line Items]
Additional borrowing capacity	$ 1,000
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
MPLX Revolving Credit Facility due July 2027 | Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 150

Debt (Senior Notes) (Details)

Debt (Senior Notes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Feb. 15, 2023	Feb. 09, 2023	Sep. 15, 2022	Aug. 25, 2022	Aug. 11, 2022	Mar. 14, 2022	Jan. 15, 2021
Series B Preferred Stock [Member]
Debt Instrument [Line Items]
Payments for Repurchase of Preferred Stock and Preference Stock	$ 600	$ 0	$ 0
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Outstanding balance		0
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 [Member]
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
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]
Debt Instrument [Line Items]
Interest rate, stated percentage				4.50%
Gain (Loss) on Extinguishment of Debt	9
Repayments of Debt	1,000
Senior Notes | Senior Note Due March 2053
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
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 | 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 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 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,500	1,500
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	1,000
Interest rate, stated percentage	4.95%
Debt Instrument, Maturity Date	Sep. 01, 2032
MPLX LP | Senior Notes | Senior Note Due March 2033
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,100	0
Interest rate, stated percentage	5%
Debt Instrument, Maturity Date	Mar. 01, 2033
MPLX LP | Senior Notes | Senior Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	989
Interest rate, stated percentage	4.50%
Debt Instrument, Maturity Date	Jul. 15, 2023
MPLX LP | Senior Notes | Senior Note Due March 2053
Debt Instrument [Line Items]
Long-term debt, gross	$ 500	0
Interest rate, stated percentage	5.65%
Debt Instrument, Maturity Date	Mar. 01, 2053
ANDX LP [Member] | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 31	31
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	$ 12	$ 23
Minimum | ANDX LP [Member] | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	4.25%
Debt Instrument, Maturity Date	Dec. 01, 2027
Minimum | MarkWest | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Debt Instrument, Maturity Date	Jul. 15, 2023
Maximum | ANDX LP [Member] | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	5.20%
Debt Instrument, Maturity Date	Dec. 01, 2047
Maximum | MarkWest | Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage	4.875%
Debt Instrument, Maturity Date	Jun. 01, 2025

Revenue Disaggregation of Reven

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 8,733	$ 8,924	$ 8,021
Revenue Not from Contract with Customer, Other	[1]	2,548	2,689	2,006
Total revenues and other income		11,281	11,613	10,027
Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		3,985	3,754	3,628
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		2,539	2,359	2,313
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		294	394	345
Product [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		250	198	145
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		1,665	2,219	1,590
Logistics and Storage [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,353	4,076	3,932
Logistics and Storage [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues and other income	[2]	6,123	5,668	5,353
Logistics and Storage [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		3,966	3,737	3,608
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		369	320	310
Logistics and Storage [Member] | Service [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,335	4,057	3,918
Logistics and Storage [Member] | Service, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		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	13	10
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		5	6	4
Logistics and Storage [Member] | Product [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		18	19	14
Gathering and Processing [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4,380	4,848	4,089
Gathering and Processing [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues and other income	[2]	5,158	5,945	4,674
Gathering and Processing [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		19	17	20
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		2,170	2,039	2,003
Gathering and Processing [Member] | Service [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		2,189	2,056	2,023
Gathering and Processing [Member] | Service, Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		294	394	345
Gathering and Processing [Member] | Product [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		237	185	135
Revenue from Contract with Customer, Excluding Assessed Tax, Third parties		1,660	2,213	1,586
Gathering and Processing [Member] | Product [Member] | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 2,191	$ 2,792	$ 2,066
[1]Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.[2]Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $776 million, $644 million and $503 million for the years ended December 31, 2023, 2022 and 2021, respectively. Third party revenues for the G&P segment were $4,827 million, $5,678 million and $4,463 million for the years ended December 31, 2023, 2022 and 2021, respectively.

Revenue Contract Balance Rollfo

Revenue Contract Balance Rollforward (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Beginning Balance Contract with Customer, Asset, Gross		$ 21	$ 25
Contract with Customer, Asset Increase (Decrease)		(18)	(4)
Contract with Customer, Asset, Reclassified to Receivable	[1]	0	0
Ending Balance Contract with Customer, Asset, Gross		3	21
Contract with Customer, Non Current Asset Reclassified to Receivable	[1]	0	0
Contract with Customer, Asset Increase (Decrease), Noncurrent		0	(1)
Contract with Customer, Asset, before Allowance for Credit Loss, Noncurrent		1	1	$ 2
Beginning Balance Deferred Revenue, Noncurrent		219
Ending Balance Deferred Revenue, Noncurrent		347	219
Contract Liability, Noncurrent, Revenue Recognized	[1]	0	0
Contract Liability, Noncurrent, Period Increase (Decrease) [Line Items]		(2)	(3)
Contract with Customer, Liability, Noncurrent		0	2	5
Contract with Customer, Liability, Change in Timeframe, Performance Obligation Satisfied, Revenue Recognized		0	0
Nonrelated Party
Deferred Revenue, Additions		42	41
Beginning Balance Deferred Revenue, Current		57	56
Deferred Revenue, Revenue Recognized	[1]	(40)	(40)
Ending Balance Deferred Revenue, Current		59	57
Beginning Balance Deferred Revenue, Noncurrent		216	135
Deferred Revenue, Noncurrent, Period Increase (Decrease)		128	81
Deferred Revenue, Noncurrent, Revenue Recognized	[1]	0	0
Ending Balance Deferred Revenue, Noncurrent		344	216
Related Party
Deferred Revenue, Additions		86	109
Beginning Balance Deferred Revenue, Current		80
Deferred Revenue, Revenue Recognized	[1]	(102)	(106)
Ending Balance Deferred Revenue, Current		81	80
Deferred Revenue from Contracts with Customers, Current		47	63	60
Beginning Balance Deferred Revenue, Noncurrent		110
Deferred Revenue, Noncurrent, Period Increase (Decrease)		4	(6)
Deferred Revenue, Noncurrent, Revenue Recognized	[1]	0	0
Ending Balance Deferred Revenue, Noncurrent		99	110
Deferred Revenue from Contracts with Customers, Noncurrent		$ 29	$ 25	$ 31
[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, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 8,500
Contract with Customer, Liability	479
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	$ 2,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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	$ 1,900
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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	$ 1,800
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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	$ 1,700
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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	$ 500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 600
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2043-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	20 years

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023		Dec. 31, 2022	Dec. 31, 2021
Supplemental Cash Flow Information [Abstract]
Interest paid (net of amounts capitalized)	$ 893		$ 813	$ 812
Income taxes paid	7		3	4
Payments on operating leases	71		73	79
Principal payments under finance lease obligations	1		2	2
Non-cash investing and financing activities:
Net transfers of property, plant and equipment (to)/from materials and supplies inventories	(8)		(1)	1
ROU assets obtained in exchange for new operating lease obligations	21		78	20
ROU assets obtained in exchange for new finance lease obligations	0		1	0
Book Value of Equity Method Investment	$ 311	[1]	$ 0	$ 0
[1]Represents the book value of MPLX’s equity method investment in Torñado prior to MPLX buying out the remaining interest in this entity. See Note 4 for additional information.

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, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplemental Cash Flow Information [Abstract]
Additions to property, plant and equipment	$ 937	$ 806	$ 529
Increase in capital accruals	82	47	11
Capital Expenditure	$ 1,019	$ 853	$ 540

Leases Lessee Disclosures (Deta

Leases Lessee Disclosures (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Long-term lease receivables		$ 264	$ 283
Operating Lease, Liability, Noncurrent		211	230
Finance Lease, Liability, to be Paid, Year One		1
Finance Lease, Liability, to be Paid, Year Two		1
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		6
Finance Lease, Liability, Payment, Due		11
Finance Lease, Liability, Undiscounted Excess Amount		5
Finance Lease, Liability	[1]	$ 6	$ 8
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Long-term debt due within one year	Long-term debt due within one year
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Long-term debt	Long-term debt
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]		Long-term debt, Long-term debt due within one year	Long-term debt, Long-term debt due within one year
Nonrelated Party
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		$ 56	$ 61	$ 71
Finance Lease, Right-of-Use Asset, Amortization		1	1	2
Finance Lease, Interest Expense		0	1	1
Finance Lease Cost		1	2	3
Variable lease cost		10	16	15
Short-term lease cost		61	45	31
Total lease cost		128	124	120
Long-term lease receivables		264	283
Operating lease liabilities		45	46
Operating Lease, Liability, Noncurrent		211	230
Lessee, Operating Lease, Liability, to be Paid, Year One		55
Lessee, Operating Lease, Liability, to be Paid, Year Two		40
Lessee, Operating Lease, Liability, to be Paid, Year Three		35
Lessee, Operating Lease, Liability, to be Paid, Year Four		31
Lessee, Operating Lease, Liability, to be Paid, Year Five		29
Lessee, Operating Lease, Liability, to be Paid, after Year Five		115
Lessee, Operating Lease, Liability, to be Paid		305
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		49
Operating Lease, Liability		256	276
Finance Lease, Liability		$ 6	$ 8
Operating Lease, Weighted Average Remaining Lease Term		9 years	9 years
Operating Lease, Weighted Average Discount Rate, Percent		4.20%	4.10%
Finance Lease, Right-of-Use Asset, before Accumulated Amortization		$ 10	$ 11
Finance Lease, Right-of-Use Asset, Accumulated Amortization		5	4
Finance Lease, Right-of-Use Asset, after Accumulated Amortization		5	7
Other current liabilities		1	1
Long-term debt		$ 5	$ 7
Finance Lease, Weighted Average Remaining Lease Term		20 years	18 years
Finance Lease, Weighted Average Discount Rate, Percent		6%	6%
Related Party
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		$ 14	$ 15	15
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		4	2	0
Short-term lease cost		1	0	0
Total lease cost		19	17	$ 15
Long-term lease receivables		227	228
Operating Lease, Liability, Current		1	1
Operating lease liabilities		1	1
Operating Lease, Liability, Noncurrent, Related Party		226	228
Lessee, Operating Lease, Liability, to be Paid, Year One		15
Lessee, Operating Lease, Liability, to be Paid, Year Two		14
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		547
Lessee, Operating Lease, Liability, to be Paid		618
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		391
Operating Lease, Liability, Related Party		$ 227	$ 229
Operating Lease, Weighted Average Remaining Lease Term		43 years	44 years
Operating Lease, Weighted Average Discount Rate, Percent		5.80%	5.80%
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Remaining Lease Term		95 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, 2023		Dec. 31, 2022		Dec. 31, 2021
Lessor, Lease, Description [Line Items]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		$ 678
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		665
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		622
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		500
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		218
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		1,087
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		3,770
Lessor, Operating Lease, Payment to be Received, Year One		876
Sales-type lease revenue, related parties		500		$ 465		$ 435
Lessor, Operating Lease, Payment to be Received, Year Two		832
Lessor, Operating Lease, Payment to be Received, Year Three		665
Lessor, Operating Lease, Payment to be Received, Year Four		500
Lessor, Operating Lease, Payment to be Received, Year Five		214
Lessor, Operating Lease, Payment to be Received, after Year Five		297
Lessor, Operating Lease, Payments to be Received		3,384
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		1,892
Sales-type Lease, Lease Receivable	[1]	1,878
Sales-type Lease, Unguaranteed Residual Asset	[2]	204
Accumulated depreciation		2,124		1,880
Property, Plant and Equipment, Net		2,596		2,697
Property Subject to or Available for Operating Lease, Gross		4,720		4,577
Sales-type Lease, Revenue		136		62		0
Deferred Revenue, Noncurrent		347		219
Contributions		31		82		160
Net Investment in Lease, before Allowance for Credit Loss, Current	[3]	251
Net Investment in Lease, before Allowance for Credit Loss, Noncurrent	[2]	1,627
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		2,082
Net Investment in Lease, Purchase		85		72		48
Pipelines And Related Assets [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		677		670
Refineries and related assets [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		1,399		1,310
Terminals and related assets [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		1,267		1,241
Barges and towing vessels [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		126		126
Gas Gathering And Transmission Equipment And Facilities [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		86		94
Processing, Fractionation And Storage Facilities [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		1,000		973
Land Building Office Equipment And Other [Member]
Lessor, Lease, Description [Line Items]
Property Subject to or Available for Operating Lease, Gross		165		163
Marathon Petroleum Corporation [Member] | Gain (loss) on sales-type lease | Limited Partners Common Units
Lessor, Lease, Description [Line Items]
Contributions	[4]			43		112
Nonrelated Party
Lessor, Lease, Description [Line Items]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		175
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		161
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		150
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		141
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		132
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		959
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		1,718
Lessor, Operating Lease, Payment to be Received, Year One		117
Operating Lease, Lease Income		243		327		376
Sales-type Lease, Selling Profit (Loss)				509	[5]	0
Sales-type Lease, Interest Income		114		46		0
Sales-type Lease, Variable Lease Income		22		16		0
Lessor, Operating Lease, Payment to be Received, Year Two		95
Lessor, Operating Lease, Payment to be Received, Year Three		75
Lessor, Operating Lease, Payment to be Received, Year Four		53
Lessor, Operating Lease, Payment to be Received, Year Five		46
Lessor, Operating Lease, Payment to be Received, after Year Five		250
Lessor, Operating Lease, Payments to be Received		636
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		778
Sales-type Lease, Lease Receivable		940	[1]	914		0
Sales-type Lease, Unguaranteed Residual Asset		78	[2]	63		0
Sales Type Lease Derecognition Properties And Equipment Net				745		0
Sales Type Lease Derecognition of Deferred Revenue				277		0
Sales-type Lease, Revenue		136		62		0
Deferred Revenue, Noncurrent		344		216		135
Net Investment in Lease, before Allowance for Credit Loss, Current	[3]	102
Net Investment in Lease, before Allowance for Credit Loss, Noncurrent	[2]	838
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		1,018
Related Party
Lessor, Lease, Description [Line Items]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One		503
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		504
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		472
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		359
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		86
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		128
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		2,052
Lessor, Operating Lease, Payment to be Received, Year One		759
Operating Lease, Lease Income		822		763		743
Sales-type Lease, Interest Income		467		447		431
Sales-type Lease, Variable Lease Income		33		18		4
Sales-type lease revenue, related parties		500		465		435
Lessor, Operating Lease, Payment to be Received, Year Two		737
Lessor, Operating Lease, Payment to be Received, Year Three		590
Lessor, Operating Lease, Payment to be Received, Year Four		447
Lessor, Operating Lease, Payment to be Received, Year Five		168
Lessor, Operating Lease, Payment to be Received, after Year Five		47
Lessor, Operating Lease, Payments to be Received		2,748
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount		1,114
Sales-type Lease, Lease Receivable	[1]	938
Sales-type Lease, Unguaranteed Residual Asset		126	[2]	87
Deferred Revenue, Noncurrent		99		110
Net Investment in Lease, before Allowance for Credit Loss, Current		149	[3]	111
Net Investment in Lease, before Allowance for Credit Loss, Noncurrent		789	[2]	883
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss		$ 1,064
Affiliated Entity
Lessor, Lease, Description [Line Items]
Sales-type Lease, Lease Receivable				87		519
Sales-type Lease, Unguaranteed Residual Asset				6		14
Sales Type Lease Derecognition Properties And Equipment Net				50		421
Sales Type Lease Derecognition of Deferred Revenue				$ 0		$ 0
Maximum
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years
Maximum | Lease Agreements, Lessor [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		9 years
Minimum
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		1 year
Minimum | Lease Agreements, Lessor [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		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 Contribution from MPC in the Consolidated Statements of Equity given the underlying agreements are between entities under common control.[5]The amount recognized on commencement date was recorded as a gain in Other income in the Consolidated Statements of Income.

Commitments and Contingencies_2

Commitments and Contingencies (Detail) - USD ($) $ in Millions		1 Months Ended
	Dec. 15, 2020	Jul. 31, 2020	Dec. 31, 2023	Dec. 31, 2022
Commitments And Contingencies [Line Items]
Loss Contingency, Damages Sought, Value		$ 187
Loss Contingency, Damages Paid, Value	$ 4
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]			Other long-term liabilities, Other Liabilities, Current	Other long-term liabilities, Other Liabilities, Current
Accrual for environmental loss contingencies			$ 19	$ 17
Capital Addition Purchase Commitments
Commitments And Contingencies [Line Items]
Contractual commitments to acquire property, plant and equipment			$ 136
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) - Minimum Committed Volume Contracts [Member] $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Other Commitments [Line Items]
2024	$ 187
2025	157
2026	145
2027	130
2028	120
2029 and thereafter	94
Total	$ 833
Minimum
Other Commitments [Line Items]
Term Of Agreements	1 year
Maximum
Other Commitments [Line Items]
Term Of Agreements	8 years