Marathon Petroleum (MPC) 10-K 26 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Entity Central Index Key	0001510295
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	FY
Amendment Flag	false
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-35054
Entity Registrant Name	Marathon Petroleum Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-1284632
Entity Address, Address Line One	539 South Main 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 Stock, par value $.01
Trading Symbol	MPC
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			$ 24.3
Entity Common Stock, Shares Outstanding		651,274,842

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Revenues and other income:
Sales and other operating revenues	$ 69,779		$ 111,148	$ 86,086
Income (loss) from equity method investments	(935)	[1]	312	299
Net gain on disposal of assets	70		278	6
Other income	118		127	198
Total revenues and other income	69,032		111,865	86,589
Costs and expenses:
Cost of revenues (excludes items below)	65,733		99,228	77,047
Impairment expense	8,426		1,197	0
Depreciation and amortization	3,375		3,225	2,170
Selling, general and administrative expenses	2,710		3,192	2,276
Restructuring expenses	367		0	0
Other taxes	668		561	406
Total costs and expenses	81,279		107,403	81,899
Income (loss) from continuing operations	(12,247)		4,462	4,690
Net interest and other financial costs	1,365		1,229	993
Income (loss) from continuing operations before income taxes	(13,612)		3,233	3,697
Provision (benefit) for income taxes on continuing operations	(2,430)		784	764
Income (loss) from continuing operations, net of tax	(11,182)		2,449	2,933
Income from discontinued operations, net of tax	1,205		806	673
Net income (loss)	(9,977)		3,255	3,606
Less net income (loss) attributable to:
Redeemable noncontrolling interest	81		81	75
Noncontrolling interests	(232)		537	751
Net income (loss) attributable to MPC	$ (9,826)		$ 2,637	$ 2,780
Basic:
Continuing operations	$ (16.99)		$ 2.78	$ 4.06
Discontinued operations	1.86		1.22	1.30
Net income (loss) per share	$ (15.13)		$ 4	$ 5.36
Weighted average shares outstanding	649		659	518
Diluted:
Continuing operations	$ (16.99)		$ 2.76	$ 4
Discontinued operations	1.86		1.21	1.28
Net income (loss) per share	$ (15.13)		$ 3.97	$ 5.28
Weighted average shares outstanding	649		664	526
[1]	2020 includes impairment expense. See Note 7 for further information.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income (loss)	$ (9,977)	$ 3,255	$ 3,606
Other comprehensive income (loss)	(192)	(176)	87
Comprehensive income (loss)	(10,169)	3,079	3,693
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	81	81	75
Noncontrolling interests	(232)	537	751
Comprehensive income (loss) attributable to MPC	(10,018)	2,461	2,867
Actuarial changes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)	(157)	(147)	75
Prior service
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)	(34)	(27)	8
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)	$ (1)	$ (2)	$ 4

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Actuarial changes
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, tax expense (benefit)	$ (51)	$ (40)	$ 14
Prior service
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, tax expense (benefit)	(11)	(17)	12
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
OCI, tax expense (benefit)	$ 0	$ (1)	$ 1

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	[1]	$ 415	$ 1,393
Receivables, less allowance for doubtful accounts		5,760	7,233
Inventories		7,999	9,804
Other current assets		2,724	893
Assets held for sale		11,389	11,135
Total current assets		28,287	30,458
Equity method investments		5,422	6,568
Property, plant and equipment, net		39,035	40,870
Goodwill		8,256	15,650
Right of use assets		1,521	1,806
Other noncurrent assets		2,637	3,204
Total assets		85,158	98,556
Current liabilities:
Accounts payable		7,803	11,222
Payroll and benefits payable		732	987
Accrued taxes		1,105	1,015
Debt due within one year		2,854	704
Operating lease liabilities		497	514
Other current liabilities		822	758
Liabilities held for sale		1,850	1,748
Total current liabilities		15,663	16,948
Long-term debt		28,730	28,020
Deferred income taxes		6,203	6,392
Defined benefit postretirement plan obligations		2,121	1,617
Long-term operating lease liabilities		1,014	1,300
Deferred credits and other liabilities		1,207	1,172
Total liabilities		54,938	55,449
Commitments and contingencies (see Note 29)
Redeemable noncontrolling interest		968	968
MPC stockholders’ equity:
Preferred stock, no shares issued and outstanding (par value $0.01 per share, 30 million shares authorized)		0	0
Common stock:
Issued – 980 million and 978 million shares (par value $0.01 per share, 2 billion shares authorized)		10	10
Held in treasury, at cost – 329 million and 329 million shares		(15,157)	(15,143)
Additional paid-in capital		33,208	33,157
Retained earnings		4,650	15,990
Accumulated other comprehensive loss		(512)	(320)
Total MPC stockholders’ equity		22,199	33,694
Noncontrolling interests		7,053	8,445
Total equity		29,252	42,139
Total liabilities, redeemable noncontrolling interest and equity		$ 85,158	$ 98,556
[1]	Excludes $140 million and $134 million of cash included in assets held for sale representing Speedway store cash.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Receivables, allowance for doubtful accounts, current	$ 18	$ 17
Preferred Stock:
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Preferred Stock, Shares Authorized	30
Common stock:
Common Stock, Shares, Issued	980	978
Common Stock, Par or Stated Value Per Share	$ 0.01
Common Stock, Shares Authorized	2,000
Treasury Stock, Shares	(329)	(329)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net income (loss)		$ (9,977)		$ 3,255	$ 3,606
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization of deferred financing costs and debt discount		69		33	70
Impairment expense		8,426		1,197	0
Depreciation and amortization		3,375		3,225	2,170
Pension and other postretirement benefits, net		220		(68)	93
Deferred income taxes		(241)		807	14
Net gain on disposal of assets		(70)		(278)	(6)
(Income) loss from equity method investments		935	[1]	(312)	(299)
Distributions from equity method investments		577		569	458
Income from discontinued operations		1,205		806	673
Changes in income tax receivable		(1,807)		(358)	238
Changes in the fair value of derivative instruments		45		(8)	(62)
Changes in operating assets and liabilities, net of effects of businesses acquired:
Current receivables		1,465		(1,717)	1,277
Inventories		1,750		(362)	965
Current accounts payable and accrued liabilities		(2,927)		2,453	(2,801)
Right of use assets and operating lease liabilities, net		(19)		(9)	0
All other, net		191		355	49
Cash provided by operating activities - continuing operations		807		7,976	5,099
Cash provided by operating activities - discontinued operations		1,612		1,465	1,059
Net cash provided by operating activities		2,419		9,441	6,158
Investing activities:
Additions to property, plant and equipment		(2,787)		(4,810)	(3,179)
Acquisitions, net of cash acquired		0		(129)	(3,822)
Disposal of assets		150		47	22
Investments – acquisitions, loans and contributions		(485)		(1,064)	(409)
Investments—redemptions, repayments and return of capital		137		98	16
All other, net		63		81	69
Cash used in investing activities - continuing operations		(2,922)		(5,777)	(7,303)
Cash used in investing activities - discontinued operations		(335)		(484)	(367)
Net cash used in investing activities		(3,257)		(6,261)	(7,670)
Financing activities:
Commercial paper – issued		2,055		0	0
Commercial paper - repayments		(1,031)		0	0
Long-term debt – borrowings		17,082		14,274	13,476
Long-term debt – repayments		(15,380)		(13,073)	(8,032)
Debt issuance costs		(50)		(22)	(86)
Issuance of common stock		11		10	24
Common stock repurchased		0		1,950	3,287
Dividends paid		(1,510)		(1,398)	(954)
Distributions to noncontrolling interests		(1,244)		(1,245)	(903)
Contributions from noncontrolling interests		0		97	12
Repurchases of noncontrolling interests		33		0	0
All other, net		(35)		(69)	(28)
Net cash provided by (used in) financing activities		(135)		(3,376)	222
Net change in cash, cash equivalents and restricted cash		(973)		(196)	(1,290)
Cash, cash equivalents, restricted cash and restricted cash equivalents, beginning balance		1,395		1,519	2,849
Cash, cash equivalents, restricted cash and restricted cash equivalents, ending balance		416		1,395	1,519
Discontinued Operations, Held-for-sale
Financing activities:
Cash, cash equivalents, restricted cash and restricted cash equivalents, beginning balance	[2]	134		206	166
Cash, cash equivalents, restricted cash and restricted cash equivalents, ending balance	[2]	$ 140		$ 134	$ 206
[1]	2020 includes impairment expense. See Note 7 for further information.
[2]	Reported as assets held for sale on our consolidated balance sheets.

Consolidated Statements of Equi

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Consolidated Statements of Equity) - USD ($) $ in Millions	Total	Cumulative effect, period of adoption, adjustment	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Retained EarningsCumulative effect, period of adoption, adjustment	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest [Member]	Noncontrolling Interest [Member]Cumulative effect, period of adoption, adjustment
Beginning balance at Dec. 31, 2017	$ 20,828	$ 68	$ 7	$ (9,869)	$ 11,262	$ 12,864	$ 66	$ (231)	$ 6,795	$ 2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	3,531					2,780			751
Dividends declared on common stock	(955)					(955)
Distributions to noncontrolling interests	(832)								(832)
Contributions from noncontrolling interests	12								12
Other comprehensive income (loss)	87							87
Shares repurchased	(3,287)			(3,287)
Shares issued - stock based compensation			1		345
Shares returned - stock based compensation				(18)
Stock based compensation	342								14
Equity transactions of MPLX & ANDX	(570)				2,357				(2,927)
Issuance of shares for Andeavor acquisition	19,766		2	(1)	19,765
Noncontrolling interest acquired from Andeavor	5,059								5,059
Ending balance at Dec. 31, 2018	44,049		10	(13,175)	33,729	14,755		(144)	8,874
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	3,174					2,637			537
Dividends declared on common stock	(1,402)					(1,402)
Distributions to noncontrolling interests	(1,164)								(1,164)
Contributions from noncontrolling interests	97								97
Other comprehensive income (loss)	(176)							(176)
Shares repurchased	(1,950)			(1,950)
Shares issued - stock based compensation					112
Shares returned - stock based compensation				(18)
Stock based compensation	101								7
Equity transactions of MPLX & ANDX	(590)				(684)				94
Ending balance at Dec. 31, 2019	42,139		10	(15,143)	33,157	15,990		(320)	8,445
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(10,058)					(9,826)			(232)
Dividends declared on common stock	(1,514)					(1,514)
Distributions to noncontrolling interests	(1,163)								(1,163)
Other comprehensive income (loss)	(192)							(192)
Shares issued - stock based compensation			0		92
Shares returned - stock based compensation				(14)
Stock based compensation	86								8
Equity transactions of MPLX & ANDX	(46)				(41)				(5)
Ending balance at Dec. 31, 2020	$ 29,252		$ 10	$ (15,157)	$ 33,208	$ 4,650		$ (512)	$ 7,053

Consolidated Statements of Eq_2

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Shares of Common Stock) - shares shares in Millions	Total	Common Stock
Beginning balance at Dec. 31, 2017		734
Shares issued - stock-based compensation		1
Shares issued - acquisitions		240
Ending balance at Dec. 31, 2018		975
Shares issued - stock-based compensation		3
Ending balance at Dec. 31, 2019	978	978
Shares issued - stock-based compensation		2
Ending balance at Dec. 31, 2020	980	980

Consolidated Statements of Eq_3

Consolidated Statements of Equity ad Redeemable Noncontrolling Interest (Shares of Treasury Stock) - shares shares in Millions	Total	Treasury Stock
Beginning balance at Dec. 31, 2017		(248)
Number of shares repurchased	(47)	(47)
Shares returned - stock-based compensation		0
Ending balance at Dec. 31, 2018		(295)
Number of shares repurchased	(34)	(34)
Shares returned - stock-based compensation		0
Ending balance at Dec. 31, 2019	(329)	(329)
Number of shares repurchased	0
Shares returned - stock-based compensation		0
Ending balance at Dec. 31, 2020	(329)	(329)

Consolidated Statements of Eq_4

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Redeemable Noncontrolling Interest) - USD ($) $ in Millions	Total	Redeemable Non-controlling Interest
Beginning balance at Dec. 31, 2017		$ 1,000
Net income (loss) attributable to redeemable noncontrolling interest	$ 75	75
Distributions to noncontrolling interests		(71)
Ending balance at Dec. 31, 2018		1,004
Net income (loss) attributable to redeemable noncontrolling interest	81	81
Distributions to noncontrolling interests		(81)
Equity transactions of MPLX & ANDX		(36)
Ending balance at Dec. 31, 2019	968	968
Net income (loss) attributable to redeemable noncontrolling interest	81	81
Distributions to noncontrolling interests		(81)
Equity transactions of MPLX & ANDX		0
Ending balance at Dec. 31, 2020	$ 968	$ 968

Consolidated Statements of Eq_5

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends declared per share of common stock (in dollars per share)	$ 2.32	$ 2.12	$ 1.84

Description of the Business and

Description of the Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business and Basis of Presentation	DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION Description of the Business We are a leading, integrated, downstream energy company headquartered in Findlay, Ohio. We operate the nation's largest refining system. We sell refined products to wholesale marketing customers domestically and internationally, to buyers on the spot market and to independent entrepreneurs who operate approximately 7,100 branded outlets. We also sell transportation fuel to consumers through approximately 1,090 direct dealer locations under long-term supply contracts. MPC’s midstream operations are primarily conducted through MPLX LP (“MPLX”), which owns and operates crude oil and light product transportation and logistics infrastructure as well as gathering, processing, and fractionation assets. We own the general partner and a majority limited partner interest in MPLX. On August 2, 2020, we entered into a definitive agreement to sell Speedway, our company-owned and operated retail transportation fuel and convenience store business, to 7-Eleven, Inc. (“7-Eleven”) for $21 billion in cash, subject to certain adjustments based on the levels of cash, debt and working capital at closing and certain other items. The taxable transaction is targeted to close by the end of the first quarter of 2021, subject to customary closing conditions and the receipt of regulatory approvals. We will retain our direct dealer business. As a result of the agreement to sell Speedway, its results are reported separately as discontinued operations in our consolidated statements of income for all periods presented and its assets and liabilities have been presented in our consolidated balance sheets as assets and liabilities held for sale. In addition, we separately disclosed the operating and investing cash flows of Speedway as discontinued operations within our consolidated statements of cash flow. See Note 5 for discontinued operations disclosures. Prior to presentation of Speedway as discontinued operations, Speedway and our retained direct dealer business were the two reporting units within our Retail segment. Beginning with the third quarter of 2020, the direct dealer business is managed as part of the Refining & Marketing segment. The results of the Refining & Marketing segment have been retrospectively adjusted to include the results of the direct dealer business in all periods presented. See Note 13 for our segment reporting disclosures. Refer to Note 8 for further information on the Andeavor acquisition, which closed on October 1, 2018, and to Notes 6 and 13 for additional information about our operations. Basis of Presentation All significant intercompany transactions and accounts have been eliminated. As a result of our agreement to sell Speedway, the following changes in our basis of presentation have occurred: • In accordance with ASC 205, Discontinued Operations, intersegment sales from our Refining & Marketing segment to Speedway are no longer eliminated as intercompany transactions and are now presented within sales and other operating revenue, since we will continue to supply fuel to Speedway subsequent to the sale to 7-Eleven. All periods presented have been retrospectively adjusted to reflect this change. • Beginning August 2, 2020, in accordance with ASC 360, Property, Plant, and Equipment, we ceased recording depreciation and amortization for Speedway’s property, plant and equipment, finite-lived intangible assets and right of use lease assets. Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

Summary of Principal Accounting

Summary of Principal Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary Of Principal Accounting Policies	SUMMARY OF PRINCIPAL ACCOUNTING POLICIES Principles Applied in Consolidation These consolidated financial statements include the accounts of our majority-owned, controlled subsidiaries and MPLX. As of December 31, 2020, we owned the general partner and 62 percent of the outstanding MPLX common units. Due to our ownership of the general partner interest, we have determined that we control MPLX and therefore we consolidate MPLX and record a noncontrolling interest for the interest owned by the public. Changes in ownership interest in consolidated subsidiaries that do not result in a change in control are recorded as equity transactions. Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority shareholders have substantive participating rights. Income from equity method investments represents our proportionate share of net income generated by the equity method investees. 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 any excess related to goodwill. Equity method investments are evaluated for impairment whenever changes in the facts and circumstances indicate an other than temporary loss in value has occurred. When the loss is deemed to be other than temporary, the carrying value of the equity method investment is written down to fair value. Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles 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. Revenue Recognition We recognize revenue based on consideration specified in contracts or agreements with customers when we satisfy our performance obligations by transferring control over products or services to a customer. Concurrent with our adoption of ASU 2014-09, Revenue from Contracts with Customers (“ASC 606”), as of January 1, 2018, we made an accounting policy election that all taxes assessed by a governmental authority that are both imposed on and concurrent with a revenue-producing transaction and collected from our customers will be recognized on a net basis within sales and other operating revenues. Our revenue recognition patterns are described below by reportable segment: • Refining & Marketing - The vast majority of our Refining & Marketing contracts contain pricing that is based on the market price for the product at the time of delivery. Our obligations to deliver product volumes are typically satisfied and revenue is recognized when control of the product transfers to our customers. Concurrent with the transfer of control, we typically receive the right to payment for the delivered product, the customer accepts the product and the customer has significant risks and rewards of ownership of the product. Payment terms require customers to pay shortly after delivery and do not contain significant financing components. • Midstream - Midstream revenue transactions typically are defined by contracts under which we sell a product or provide a service. Revenues from sales of product are recognized when control of the product transfers to the customer. Revenues from sales of services are recognized over time when the performance obligation is satisfied as services are provided in a series. We have elected to use the output measure of progress to recognize revenue based on the units delivered, processed or transported. The transaction prices in our Midstream contracts often have both 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 at each period end. Refer to Note 23 for disclosure of our revenue disaggregated by segment and product line and to Note 13 for a description of our reportable segment operations. Crude Oil and Refined Product Exchanges and Matching Buy/Sell Transactions We enter into exchange contracts and matching buy/sell arrangements whereby we agree to deliver a particular quantity and quality of crude oil or refined products at a specified location and date to a particular counterparty and to receive from the same counterparty the same commodity at a specified location on the same or another specified date. The exchange receipts and deliveries are nonmonetary transactions, with the exception of associated grade or location differentials that are settled in cash. The matching buy/sell purchase and sale transactions are settled in cash. No revenues are recorded for exchange and matching buy/sell transactions as they are accounted for as exchanges of inventory. The exchange transactions are recognized at the carrying amount of the inventory transferred. 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. Restricted Cash Restricted cash consists of cash and investments that must be maintained as collateral for letters of credit issued to certain third-party producer customers. The balances will be outstanding until certain capital projects are completed and the third party releases the restriction. Accounts Receivable and Allowance for Doubtful Accounts Our receivables primarily consist of customer accounts receivable. Customer receivables are recorded at the invoiced amounts and generally do not bear interest. Allowances for doubtful accounts are generally recorded when it becomes probable the receivable will not be collected and are booked to bad debt expense. The allowance for doubtful accounts is the best estimate of the amount of probable credit losses in customer accounts receivable. We review the allowance quarterly and past-due balances over 180 days are reviewed individually for collectability. We mitigate credit risk with master netting agreements with companies engaged in the crude oil or refinery feedstock trading and supply business or the petroleum refining industry. A master netting agreement generally provides for a once per month net cash settlement of the accounts receivable from and the accounts payable to a particular counterparty. 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 assets. 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 equipment leases. The lease component of the payment for the marine and equipment asset classes is determined using a relative standalone selling price. See Note 28 for additional disclosures about our lease contracts. Inventories Inventories are carried at the lower of cost or market value. Cost of inventories is determined primarily under the LIFO method. Costs for crude oil and refined product inventories are aggregated on a consolidated basis for purposes of assessing if the LIFO cost basis of these inventories may have to be written down to market value. Derivative Instruments We use derivatives to economically hedge a portion of our exposure to commodity price risk and, historically, to interest rate risk. Our use of selective derivative instruments that assume market risk is limited. All derivative instruments (including derivative instruments embedded in other contracts) are recorded at fair value. Certain commodity derivatives are reflected on the consolidated balance sheets on a net basis by counterparty as they are governed by master netting agreements. Cash flows related to derivatives used to hedge commodity price risk and interest rate risk are classified in operating activities with the underlying transactions. Derivatives not designated as accounting hedges Derivatives that are not designated as accounting hedges may include commodity derivatives used to hedge price risk on (1) inventories, (2) fixed price sales of refined products, (3) the acquisition of foreign-sourced crude oil, (4) the acquisition of ethanol for blending with refined products, (5) the sale of NGLs, (6) the purchase of natural gas and (7) the purchase of soybean oil. Changes in the fair value of derivatives not designated as accounting hedges are recognized immediately in net income. Concentrations of credit risk All of our financial instruments, including derivatives, involve elements of credit and market risk. The most significant portion of our credit risk relates to nonperformance by counterparties. The counterparties to our financial instruments consist primarily of major financial institutions and companies within the energy industry. To manage counterparty risk associated with financial instruments, we select and monitor counterparties based on an assessment of their financial strength and on credit ratings, if available. Additionally, we limit the level of exposure with any single counterparty. 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, which range from one year to 61 years. Such assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset group may not be recoverable. If the sum of the expected undiscounted future cash flows from the use of the asset group and its eventual disposition is less than the carrying amount of the asset group, an impairment assessment is performed and the excess of the book value over the fair value of the asset group 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 in net income. Gains on the disposal of property, plant and equipment are recognized when earned, 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 expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset. Goodwill and Intangible Assets 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/or 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. 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. Intangibles not subject to amortization are tested for impairment annually and when circumstances indicate that the fair value is less than the carrying amount of the intangible. If the fair value is less than the carrying value, an impairment is recorded for the difference. Major Maintenance Activities Costs for planned turnaround and other major maintenance activities are expensed in the period incurred. These types of costs include contractor repair services, materials and supplies, equipment rentals and our labor 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 The fair value of asset retirement obligations is recognized in the period in which the obligations are incurred if a reasonable estimate of fair value can be made. The majority of our recognized asset retirement liability relates to conditional asset retirement obligations for removal and disposal of fire-retardant material from certain refining facilities. The remaining recognized asset retirement liability relates to other refining assets, certain pipelines and processing facilities and other related pipeline assets. The fair values recorded for such obligations are based on the most probable current cost projections. Asset retirement obligations have not been recognized for some 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. The asset retirement obligations principally include the hazardous material disposal and removal or dismantlement requirements associated with the closure of certain refining, terminal, pipeline and processing assets. Our practice is to keep our assets in good operating condition through routine repair and maintenance of component parts in the ordinary course of business and by continuing to make improvements based on technological advances. As a result, we believe that generally these assets have no expected settlement date for purposes of estimating asset retirement obligations since the dates or ranges of dates upon which we would retire these assets cannot be reasonably estimated at this time. Income Taxes Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their tax bases. Deferred tax assets are recorded when it is more likely than not that they will be realized. The realization of deferred tax assets is assessed periodically based on several factors, primarily our expectation to generate sufficient future taxable income. Stock-Based Compensation Arrangements The fair value of stock options granted to our employees is estimated on the date of grant using the Black-Scholes option pricing model. The model employs various assumptions based on management’s estimates at the time of grant, which impact the calculation of fair value and ultimately, the amount of expense that is recognized over the vesting period of the stock option award. Of the required assumptions, the expected life of the stock option award and the expected volatility of our stock price have the most significant impact on the fair value calculation. The average expected life is based on our historical employee exercise behavior. The assumption for expected volatility of our stock price reflects a weighting of 50 percent of our common stock implied volatility and 50 percent of our common stock historical volatility. The fair value of restricted stock awards granted to our employees is determined based on the fair market value of our common stock on the date of grant. The fair value of performance unit awards granted to our employees is estimated on the date of grant using a Monte Carlo valuation model. Our stock-based compensation expense is recognized based on management’s estimate of the awards that are expected to vest, using the straight-line attribution method for all service-based awards with a graded vesting feature. If actual forfeiture results are different than expected, adjustments to recognized compensation expense may be required in future periods. Unearned stock-based compensation is charged to equity when restricted stock awards are granted. Compensation expense is recognized over the vesting period and is adjusted if conditions of the restricted stock award are not met. 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 surplus 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. For material acquisitions, management engages an independent valuation specialist to assist with the determination of fair value of the assets acquired, liabilities assumed, noncontrolling interest, 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 interest, 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 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 date, and not later than one year from the acquisition date, we will record any material adjustments to the initial estimate based on new information obtained that would have existed as of the date of the acquisition. Any 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. Environmental Credits and Obligations In order to comply with certain regulations, specifically the RFS2 requirements implemented by the EPA and the cap-and-trade emission reduction program and low carbon fuel standard implemented by the state of California, we are required to reduce our emissions, blend certain levels of biofuels or obtain allowances or credits to offset the obligations created by our operations. In regard to each program, we record an asset, included in other current or other noncurrent assets on the balance sheet, for allowances or credits owned in excess of our anticipated current period compliance requirements. The asset value is based on the product of the excess allowances or credits as of the balance sheet date, if any, and the weighted average cost of those allowances or credits. We record a liability, included in other current or other noncurrent liabilities on the balance sheet, when we are deficient allowances or credits based on the product of the deficient amount as of the balance sheet date, if any, and the market price of the allowances or credits at the balance sheet date. The cost of allowances or credits used for compliance is reflected in cost of revenues on the income statement. Any gains or losses on the sale or expiration of allowances or credits are classified as other income on the income statement. Proceeds from the sale of allowances or credits are reported in investing activities - all other, net on the cash flow statement.

Accounting Standards

Accounting Standards	12 Months Ended
	Dec. 31, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Standards	ACCOUNTING STANDARDS Recently Adopted Effective January 1, 2020, we adopted ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” using the modified retrospective transition method. The amendment requires entities to consider a broader range of information to estimate expected credit losses, which may result in earlier recognition of losses. The ASU requires the company to utilize an expected loss methodology in place of the incurred loss methodology for financial instruments, including trade receivables, and off-balance sheet credit exposures. Adoption of the standard did not have a material impact on our financial statements. We are exposed to credit losses primarily through our sales of refined petroleum products, crude oil and midstream services. We assess each customer’s ability to pay through our credit review process. The credit review process considers various factors such as external credit ratings, a review of financial statements to determine liquidity, leverage, trends and business specific risks, market information, pay history and our business strategy. Customers that do not qualify for payment terms are required to prepay or provide a letter of credit. We monitor our ongoing credit exposure through timely review of customer payment activity. At December 31, 2020, we reported $5,760 million of accounts and notes receivable, net of allowances of $18 million. We are also exposed to credit losses from off-balance sheet exposures, such as guarantees of joint venture debt. See Note 29 for more information on these off-balance sheet exposures. We also adopted the following ASUs during 2020, none of which had a material impact to our financial statements or financial statement disclosures: ASU Effective Date 2018-13 Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement January 1, 2020 2020-04 Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting April 1, 2020 Not Yet Adopted ASU 2019-12, Income Taxes (Topic 740) - Simplifying the Accounting for Income Taxes

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Restructuring	RESTRUCTURING During the third quarter of 2020, we indefinitely idled our refinery located in Gallup, New Mexico and initiated actions to strategically reposition our Martinez, California refinery to a renewable diesel facility. We also approved an involuntary workforce reduction plan. In connection with these strategic actions, we recorded restructuring expenses of $367 million in 2020. The indefinite idling of the Gallup refinery and actions to strategically reposition the Martinez refinery to a renewable diesel facility resulted in $195 million of restructuring expenses. Of the $195 million of restructuring expenses, we expect $130 million to settle in cash for costs related to decommissioning refinery processing units and storage tanks and fulfilling environmental remediation obligations. Additionally, we recorded a non-cash reserve against our materials and supplies inventory at these facilities of $51 million. The involuntary workforce reduction plan, together with employee reductions resulting from our actions affecting the Gallup and Martinez refineries, affected approximately 2,050 employees. We recorded $172 million of restructuring expenses for separation benefits payable under our employee separation plan and certain collective bargaining agreements that we expect to settle in cash. Certain of the affected MPC employees provided services to MPLX. MPLX has various employee services agreements and secondment agreements with MPC pursuant to which MPLX reimburses MPC for employee costs, along with the provision of operational and management services in support of MPLX’s operations. Pursuant to such agreements, MPC was reimbursed by MPLX for $37 million of the $172 million of restructuring expenses recorded for these actions. Restructuring expenses were accrued as restructuring reserves within accounts payable, payroll and benefits payable, other current liabilities and deferred credits and other liabilities within our consolidated balance sheets. We expect cash payments for the majority of these reserves to occur within the next nine months. (In millions) Employee separation costs Exit and disposal costs Total Restructuring reserve balance at September 30, 2020 (a) $ 158 $ 133 $ 291 Adjustments 14 5 19 Cash payments (134) (35) (169) Restructuring reserve balance at December 31, 2020 $ 38 $ 103 $ 141 (a) The restructuring reserve was zero until the third quarter of 2020.

Discontinued Operations and Ass

Discontinued Operations and Assets Held for Sale	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations and Assets Held for Sale	DISCONTINUED OPERATIONS AND ASSETS HELD FOR SALE On August 2, 2020, we entered into a definitive agreement to sell Speedway to 7-Eleven for $21 billion, subject to certain adjustments based on the levels of cash, debt and working capital at closing and certain other items. The taxable transaction is targeted to close in the first quarter of 2021, subject to customary closing conditions and the receipt of regulatory approvals. As a result of the agreement to sell Speedway, its results are reported separately as discontinued operations, net of tax, in our consolidated statements of income for all periods presented and its assets and liabilities have been presented in our consolidated balance sheets as assets and liabilities held for sale. Additionally, beginning August 2, 2020, in accordance with ASC 360, Property, Plant, and Equipment, we ceased recording depreciation and amortization for Speedway’s property, plant and equipment, finite-lived intangible assets and right of use lease assets. In addition, we separately disclosed the operating and investing cash flows of Speedway as discontinued operations within our consolidated statements of cash flow. The following tables present Speedway results as reported in income from discontinued operations, net of tax, within our consolidated statements of income and the carrying value of assets and liabilities as presented within assets and liabilities held for sale on our consolidated balance sheets. (In millions) 2020 2019 2018 Total revenues and other income $ 19,920 $ 26,793 $ 22,051 Costs and expenses: Cost of revenues (excludes items below) 17,573 24,860 20,557 Depreciation and amortization 244 413 320 Selling, general and administrative expenses 323 216 142 Other taxes 193 190 151 Total costs and expenses 18,333 25,679 21,170 Income from operations 1,587 1,114 881 Net interest and other financial costs 20 18 10 Income before income taxes 1,567 1,096 871 Provision for income taxes 362 290 198 Income from discontinued operations, net of tax $ 1,205 $ 806 $ 673 December 31, (In millions) 2020 2019 Assets Cash and cash equivalents $ 140 $ 134 Receivables 217 246 Inventories 438 439 Other current assets 34 28 Equity method investments 311 330 Property, plant and equipment, net 4,784 4,745 Goodwill 4,390 4,390 Right of use assets 719 653 Other noncurrent assets 168 170 Total assets classified as held for sale $ 11,201 $ 11,135 Liabilities Accounts payable $ 300 $ 401 Payroll and benefits payable 168 139 Accrued taxes 178 171 Debt due within one year 8 7 Operating lease liabilities 94 90 Other current liabilities 170 139 Long-term debt 122 107 Defined benefit postretirement plan obligations 25 26 Long-term operating lease liabilities 598 575 Deferred credits and other liabilities 86 93 Total liabilities classified as held for sale $ 1,749 $ 1,748 Separation Agreements In connection with the definitive agreement to sell Speedway, we have agreed to enter into a 15-year fuel supply agreement, at closing, through which we will continue to supply fuel to Speedway subsequent to the sale to 7-Eleven. Due to our expected continuing involvement with Speedway through a fuel supply agreement, intersegment sales from our Refining & Marketing segment to Speedway are no longer eliminated as intercompany transactions and are now presented within sales and other operating revenue. Purchase of Speedway’s Interest in PFJ Southeast During the fourth quarter of 2020, Pilot Travel Centers LLC exercised an option to purchase our 29 percent interest in PFJ Southeast LLC (“PFJ”), subject to customary closing conditions and the receipt of regulatory approvals. PFJ has been accounted for as an asset held for sale as of September 30, 2020 and is reported as the equity method investment balance in the above table.

Master Limited Partnership

Master Limited Partnership	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Master Limited Partnerships	MASTER LIMITED PARTNERSHIP We own the general partner and a majority limited partner interest in MPLX, which owns and operates crude oil and light product transportation and logistics infrastructure as well as gathering, processing, and fractionation assets. We control MPLX through our ownership of the general partner interest and, as of December 31, 2020, we owned approximately 62 percent of the outstanding MPLX common units. Javelina Assets Held-for-Sale On December 23, 2020, MPLX entered into an agreement with a third party to sell all 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”). Javelina’s assets and liabilities have been presented within our consolidated balance sheets as assets and liabilities held for sale as of December 31, 2020. On February 12, 2021, MPLX completed the sale of Javelina. 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. MPLX may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, tender offers, accelerated unit repurchases or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing and amount of repurchases will depend upon several factors, including market and business conditions, and repurchases may be initiated, suspended or discontinued at any time. The repurchase authorization has no expiration date. During the year ended December 31, 2020, 1,473,843 common units had been repurchased at an average cost per unit of $22.29. Total cash paid for units repurchased during the year was $33 million and $967 million remained outstanding on the program for future repurchases as of December 31, 2020. As of December 31, 2020, MPLX had agreements to acquire 99,406 additional common units for $2 million, which settled in early January 2021. Redemption of Business from MPLX On July 31, 2020, Western Refining Southwest, Inc. (now known as Western Refining Southwest LLC) (“WRSW”), a wholly owned subsidiary of MPC, entered into a Redemption Agreement (the “Redemption Agreement”) with MPLX, pursuant to which MPLX transferred to WRSW all of the outstanding membership interests in Western Refining Wholesale, LLC, (“WRW”) in exchange for the redemption of MPLX common units held by WRSW. The transaction effects the transfer to MPC of the Western wholesale distribution business that MPLX acquired as a result of its acquisition of Andeavor Logistics LP (“ANDX”). Beginning in the third quarter of 2020, the results of these operations are presented in MPC’s Refining & Marketing segment. At the closing, per the terms of Redemption Agreement, MPLX redeemed 18,582,088 MPLX common units (the “Redeemed Units”) held by WRSW. The number of Redeemed Units was calculated by dividing WRW’s aggregate valuation of $340 million by the simple average of the volume weighted average NYSE prices of an MPLX common unit for the ten trading days ending at market close on July 27, 2020. The transaction resulted in a minor decrease in MPC’s ownership interest in MPLX. MPLX’s Acquisition of ANDX On July 30, 2019, MPLX completed its acquisition of ANDX, and ANDX survived as a wholly owned subsidiary of MPLX. At the effective time of the ANDX acquisition, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by MPC were converted into the right to receive 1.0328 MPLX common units. Additionally, as a result of MPLX’s acquisition of MPLX, 600,000 ANDX preferred units were converted into 600,000 preferred units of MPLX (“Series B preferred units”). Series B preferred unitholders are entitled to receive, when and if declared by the board of directors of MPLX’s general partner, a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three month LIBOR plus 4.652 percent. MPC accounted for this transaction as a common control transaction, as defined by ASC 805, which resulted in an increase to noncontrolling interest and a decrease to additional paid-in capital of approximately $55 million, net of tax. During the third quarter of 2019, we pushed down to MPLX the portion of the goodwill attributable to ANDX as of October 1, 2018, the date of our acquisition of Andeavor. Due to this push down of goodwill, we also recorded an incremental $642 million deferred tax liability associated with the portion of the non-deductible goodwill attributable to the noncontrolling interest in MPLX with an offsetting reduction of our additional paid-in capital balance. We have consolidated ANDX since we acquired Andeavor on October 1, 2018 in accordance with ASC 810. Dropdowns to MPLX and GP/IDR Exchange On February 1, 2018, we contributed our refining logistics assets and fuels distribution services to MPLX in exchange for $4.1 billion in cash and approximately 112 million common units and 2 million general partner units from MPLX. MPLX financed the cash portion of the transaction with a $4.1 billion 364-day term loan facility, which was entered into on January 2, 2018. We agreed to waive approximately one-third of the first quarter 2018 distributions on the common units issued in connection with this transaction. The contributions of these assets were accounted for as transactions between entities under common control and we did not record a gain or loss. Immediately following the February 1, 2018 dropdown to MPLX, our IDRs were cancelled and our economic general partner interest was converted into a non-economic general partner interest, all in exchange for 275 million newly issued MPLX common units (“GP/IDR Exchange”). As a result of this transaction, the general partner units and IDRs were eliminated, are no longer outstanding and no longer participate in distributions of cash from MPLX. Agreements We have various long-term, fee-based commercial agreements with MPLX. Under these agreements, MPLX provides transportation, storage, distribution and marketing services to us. With certain exceptions, these agreements generally contain minimum volume commitments. These transactions are eliminated in consolidation but are reflected as intersegment transactions between our Refining & Marketing and Midstream segments. We also have agreements with MPLX that establish fees for operational and management services provided between us and MPLX and for executive management services and certain general and administrative services provided by us to MPLX. These transactions are eliminated in consolidation but are reflected as intersegment transactions between our Corporate and Midstream segments. Noncontrolling Interest As a result of equity transactions of MPLX and ANDX, we are required to adjust non-controlling interest and additional paid-in capital. Changes in MPC’s additional paid-in capital resulting from changes in its ownership interest in MPLX and ANDX were as follows: (In millions) 2020 2019 2018 Increase due to the issuance of MPLX common units and general partner units to MPC $ — $ — $ 1,114 Increase due to GP/IDR Exchange — — 1,808 Increase (decrease) due to the issuance of MPLX & ANDX common units (27) (51) 6 Tax impact (14) (633) (571) Increase (decrease) in MPC's additional paid-in capital, net of tax $ (41) $ (684) $ 2,357

Impairments

Impairments	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Impairments	IMPAIRMENTS The outbreak of COVID-19 and its development into a pandemic in March 2020 have resulted in significant economic disruption globally. Actions taken by various governmental authorities, individuals and companies around the world to prevent the spread of COVID-19 through social distancing have restricted travel, many business operations, public gatherings and the overall level of individual movement and in-person interaction across the globe. These actions have, in turn significantly reduced global economic activity and resulted in a decrease in motor vehicle usage and demand for gasoline and a dramatic reduction in airline flights. These macroeconomic conditions and certain global geopolitical events in the first quarter of 2020 contributed to a significant decline in crude oil prices as well as an increase in crude oil price volatility. The decrease in demand for refined petroleum products has resulted in a significant decrease in the price and volume of the refined petroleum products we produce and sell as compared to 2019. During the first quarter of 2020, the overall deterioration in the economy and the environment in which we operate, the related changes to our expected future cash flows, as well as a sustained decrease in share price were considered triggering events requiring the performance of various tests of the carrying values of our assets. Triggering events requiring the performance of various tests of the carrying value of our Midstream assets were also identified by MPLX as a result of the overall deterioration in the economy and the environment in which MPLX and its customers operate, which led to a reduction in forecasted volumes processed by the systems operated by MarkWest Utica EMG, L.L.C., MPLX’s equity method investee, as well as a sustained decrease in the MPLX unit price. These tests resulted in the majority of the impairment charges in 2020, as discussed below. The table below provides information related to the impairments recognized during 2020 and 2019, along with the location of these impairments within the consolidated statements of income. (In millions) Income Statement Line 2020 2019 Goodwill Impairment expense $ 7,394 $ 1,197 Equity method investments Income (loss) from equity method investments 1,315 42 Long-lived assets Impairment expense (a) 1,032 — Total impairments $ 9,741 $ 1,239 (a) The remaining difference not described in the narrative below is related to certain immaterial Midstream assets. Goodwill During the first quarter of 2020, we recorded an impairment of goodwill of $7.33 billion. See Note 19 for detail by segment. The goodwill impairment within the Refining & Marketing segment was primarily driven by the effects of COVID-19 and the decline in commodity prices. The impairment within the Midstream segment was primarily driven by additional information related to the slowing of drilling activity, which has reduced production growth forecasts from MPLX’s producer customers. During the third quarter of 2020, we recorded an impairment of goodwill of $64 million. The $64 million of goodwill was transferred from our Midstream segment to our Refining & Marketing segment during the third quarter of 2020 in connection with the transfer to MPC of the MPLX wholesale distribution business as described in Note 6. The transfer required goodwill impairment tests for the transferor and transferee reporting units. Our Refining & Marketing reporting unit that recorded the $64 million impairment expense has no remaining goodwill. The fair values of the reporting units for the first quarter of 2020 goodwill impairment analysis were determined based on applying both a discounted cash flow method, or income approach, as well as a market approach. The discounted cash flow fair value estimate is based on known or knowable information at the measurement date. The significant assumptions that were used to develop the estimates of the fair values under the discounted cash flow method included management’s best estimates of the expected future results and discount rates, which range from 9.0 percent to 13.5 percent across all reporting units. Significant assumptions that were used to estimate the MPLX Eastern Gathering and Processing and MPLX Crude Gathering reporting units’ fair values under the discounted cash flow method included management’s best estimates of the discount rate, as well as estimates of future cash flows, which are impacted primarily by producer customer’s 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 interim goodwill impairment test will prove to be an accurate prediction of the future. The fair value measurements for the individual reporting units’ overall fair values represent Level 3 measurements. During the fourth quarter of 2019, we recorded an impairment of goodwill in our Midstream segment. As a result of the merger of MPLX and ANDX in 2019 and subsequent changes to MPLX’s internal organization structure, the number of reporting units within our Midstream segment was reduced from 16 to 7 in conjunction with the annual impairment test, however, this change in structure did not have any impact on MPC’s operating segments. Reporting units are determined based on the way in which segment management operates and reviews each operating segment. MPLX performed a goodwill impairment assessment prior to the change in reporting units in addition to performing an impairment assessment immediately following the change in their reporting units. Significant assumptions used to estimate the reporting units’ fair value include the discount rate as well as estimates of future cash flows, which are impacted primarily by producer customers’ development plans, which impact future volumes and capital requirements. After MPLX performed its evaluations related to the impairment of goodwill, we recorded an impairment of $1,156 million prior to the change in reporting units and additional impairment of $41 million subsequent to the change in reporting units. The remainder of the reporting units fair values were in excess of their carrying values. The impairment was primarily driven by the updated guidance related to the slowing of drilling activity which has reduced production growth forecasts from MPLX’s producer customers. The fair value of the reporting units for the fourth quarter of 2019 goodwill impairment analysis was determined based on applying both a discounted cash flow or income approach as well as a market approach. The discounted cash flow fair value estimate is based on known or knowable information at the measurement date. The significant assumptions that were used to develop the estimates of the fair values under the discounted cash flow method included management’s best estimates of the expected future results and discount rates, which range from 9.0 percent to 10.0 percent. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the annual goodwill impairment test will prove to be an accurate prediction of the future. The fair value measurements for the individual reporting units’ overall fair values, and the fair values of the goodwill assigned thereto, represent Level 3 measurements. Equity Method Investments During the first quarter of 2020, we recorded equity method investment impairment charges totaling $1.315 billion, of which $1.25 billion related to MarkWest Utica EMG, L.L.C. and its investment in Ohio Gathering Company, L.L.C. The impairments were largely due to a reduction in forecasted volumes gathered and processed by the systems operated by the equity method investments. The fair value of the investments were determined based upon applying a discounted cash flow method, an income approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future cash flows, including prices and volumes, the weighted average cost of capital and the long-term growth rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment test will prove to be an accurate prediction of the future. The fair value of these equity method investments represents a Level 3 measurement. During the fourth quarter of 2019, two joint ventures in which MPLX has an interest recorded impairments, which impacted the amount of income from equity method investments during the period by approximately $28 million. For one of the joint ventures, MPLX also had a basis difference which was being amortized over the life of the underlying assets. As a result of the impairment recorded by the joint venture, MPLX also assessed this basis difference for impairment and recorded approximately $14 million of impairment expense during the fourth quarter related to this investment. Long-lived Assets Long-lived assets (primarily consisting of property, plant and equipment, intangible assets other than goodwill, and right of use assets) used in operations are assessed for impairment whenever changes in facts and circumstances indicate that the carrying value of the assets may not be recoverable based on the expected undiscounted future cash flow of an asset group. For purposes of impairment evaluation, long-lived assets must be grouped at the lowest level for which independent cash flows can be identified, which generally is the refinery and associated distribution system level for Refining & Marketing segment assets and the plant level or pipeline system level for Midstream segment assets. If the sum of the undiscounted estimated pretax cash flows is less than the carrying value of an asset group, fair value is determined, and the carrying value is written down to the determined fair value. During the first quarter of 2020, we identified long-lived asset impairment triggers relating to all of our refinery asset groups within the Refining & Marketing segment as a result of decreases to the Refining & Marketing segment expected future cash flows. The cash flows associated with these assets were significantly impacted by the effects of COVID-19 and commodity price declines. We performed recoverability tests for each refinery asset group by comparing the undiscounted estimated pretax cash flows to the carrying value of each asset group. Only the Gallup refinery’s carrying value exceeded its undiscounted estimated pretax cash flows. It was determined that the fair value of the Gallup refinery’s property, plant and equipment was less than the carrying value. As a result, we recorded a charge of $142 million in the first quarter of 2020 to impairment expense on the consolidated statements of income. The fair value measurements for the Gallup refinery assets represent Level 3 measurements. During the second quarter of 2020, we identified long-lived asset impairment triggers relating to all of our refinery asset groups within the Refining & Marketing segment, except the Gallup refinery as it had been impaired to its estimated salvage value in the first quarter, as a result of continued unfavorable macroeconomic conditions impacting the Refining & Marketing segment expected future cash flows. We performed recoverability tests for each refinery asset group by comparing the undiscounted estimated pretax cash flows to the carrying value of each asset group. All of these refinery asset groups’ undiscounted estimated pretax cash flows exceeded their carrying value by at least 17 percent. The determination of undiscounted estimated pretax cash flows for the first and second quarter refinery asset group recoverability tests utilized significant assumptions including management’s best estimates of the expected future cash flows, allocation of certain Refining & Marketing segment cash flows to the individual refinery asset groups, the estimated useful life of certain refinery asset groups, and the estimated salvage value of certain refinery asset groups. On August 3, 2020, we announced our plans to evaluate possibilities to strategically reposition our Martinez refinery, including the potential conversion of the refinery into a renewable diesel facility. Subsequent to August 3, 2020, we progressed activities associated with the conversion of the Martinez refinery to a renewable diesel facility, including applying for permits, advancing discussions with feedstock suppliers, and beginning detailed engineering activities. As envisioned, the Martinez facility would start producing approximately 260 million gallons per year of renewable diesel by the second half of 2022, with a potential to build to full capacity of approximately 730 million gallons per year by the end of 2023. As a result of the progression of these activities, we identified assets that would be repurposed and utilized in a renewable diesel facility configuration and assets that would be abandoned since they had no function in a renewable diesel facility configuration. This change in our intended use for the Martinez refinery is a long-lived asset impairment trigger for the assets that would be repurposed and remain as part of the Martinez asset group. We assessed the asset group for impairment by comparing the undiscounted estimated pretax cash flows to the carrying value of the asset group and the undiscounted estimated pretax cash flows exceeded the Martinez asset group carrying value. We recorded impairment expense of $342 million for the abandoned assets as we are no longer using these assets and have no expectation to use these assets in the future. Additionally, as a result of our efforts to progress the conversion of Martinez refinery into a renewable diesel facility, MPLX cancelled in-process capital projects related to its Martinez refinery logistics operations resulting in impairments of $27 million in the third quarter of 2020. In the fourth quarter of 2020, we concluded the evaluation of our intended use of MPLX terminal assets near the Gallup refinery and determined that the assets were abandoned, resulting in an impairment charge of $67 million. Following this conclusion, we revised the estimate of the salvage value for the Gallup refinery asset group resulting in an additional $44 million impairment charge. These charges are included in impairment expense on our consolidated statements of income. The determinations of expected future cash flows and the salvage values of refineries, as described earlier, require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of our impairment analysis will prove to be an accurate prediction of the future. Should our assumptions significantly change in future periods, it is possible we may determine the carrying values of certain of our refinery asset groups exceed the undiscounted estimated pretax cash flows of their refinery asset groups, which would result in future impairment charges. During the first quarter of 2020, we identified an impairment trigger relating to asset groups within MPLX’s Western Gathering and Processing (“G&P”) reporting unit as a result of significant changes to expected future cash flows for these asset groups resulting from the effects of COVID-19. The cash flows associated with these assets were significantly impacted by volume declines reflecting decreased forecasted producer customer production as a result of lower commodity prices. We assessed each asset group within the Western G&P reporting unit for impairment. It was determined that the fair value of the East Texas G&P asset group’s underlying assets were less than the carrying value. As a result, MPLX recorded impairment charges totaling $350 million related to its property, plant and equipment and intangibles, which are included in impairment expense on our consolidated statements of income. Fair value of property, plant and equipment was determined using a combination of an income and cost approach. The income approach utilized significant assumptions including management’s best estimates of the expected future cash flows and the estimated useful life of the asset group. The cost approach utilized assumptions for the current replacement costs of similar assets adjusted for estimated depreciation and deterioration of the existing equipment and economic obsolescence. The fair value of the intangibles was determined based

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS Acquisition of Andeavor On October 1, 2018, we acquired Andeavor. Under the terms of the merger agreement, Andeavor stockholders had the option to choose 1.87 shares of MPC common stock or $152.27 in cash per share of Andeavor common stock. The merger agreement included election proration provisions that resulted in approximately 22.9 million shares of Andeavor common stock being converted into cash consideration and the remaining 128.2 million shares of Andeavor common stock being converted into stock consideration. Andeavor stockholders received in the aggregate approximately 239.8 million shares of MPC common stock and approximately $3.5 billion in cash in connection with the Andeavor acquisition. The fair value of the MPC shares issued was determined on the basis of the closing market price of MPC’s common shares on the acquisition date. The cash portion of the purchase price was funded using cash on hand. At the time of the acquisition, all Andeavor equity awards, with the exception of non-employee director units, were converted to MPC equity awards. The converted equity awards continue to be governed by the same terms and conditions as were applicable to such Andeavor equity awards immediately prior to the acquisition. We recognized $203 million of purchase consideration to reflect the portion of the fair value of the time-based converted equity awards attributable to pre-combination service completed by the award holders. The non-employee director units were accelerated in full and cancelled and the holders of such units received an amount of cash equal to the number of shares of Andeavor common stock subject to such non-employee director units multiplied by the cash consideration per share. Our financial results reflect the results of Andeavor from October 1, 2018, the date of the acquisition. The components of the fair value of consideration transferred are as follows: (In millions) Fair value of MPC shares issued $ 19,766 Cash payment to Andeavor stockholders 3,486 Cash settlement of non-employee director units 7 Fair value of converted equity awards 203 Total fair value of consideration transferred $ 23,462 The purchase consideration allocation resulted in the recognition of $17.3 billion in goodwill, of which $1.0 billion is tax deductible due to a carryover basis from Andeavor. Our Refining & Marketing, Midstream and former Retail segment recognized $5.2 billion, $8.1 billion and $3.9 billion of goodwill, respectively. The recognized goodwill represents the value expected to be created by further optimization of crude supply, a nationwide retail and marketing platform, diversification of our refining and midstream footprints and optimization of information systems and business processes. See Note 7 for information regarding impairments recorded in 2020 and 2019. We recognized $47 million in acquisition costs. Additionally, we recognized various other transaction-related costs, including employee-related costs associated with the Andeavor acquisition. All of these costs are reflected in selling, general and administrative expenses. The employee-related costs are primarily due to pre-existing Andeavor change in control and equity award agreements that create obligations and accelerated equity vesting upon MPC notifying employees of significant changes to or elimination of their responsibilities. Andeavor’s results have been included in MPC’s financial statements for the period subsequent to the date of the acquisition on October 1, 2018. Andeavor contributed revenues of approximately $11.3 billion including Speedway for the period from October 1 through December 31, 2018. We do not believe it is practical to disclose Andeavor’s contribution to earnings for the period from October 1, 2018 through December 31, 2018 as our integration efforts have resulted in the elimination of Andeavor stand-alone discrete financial information due mainly to our inclusion of Andeavor inventory in our consolidated LIFO inventory pools, which does not allow us to objectively distinguish the cost of sales between the two historical reporting entities. Pro Forma Financial Information The following unaudited pro forma financial information presents consolidated results assuming the Andeavor acquisition occurred on January 1, 2017. (In millions) 2018 Sales and other operating revenues $ 131,921 Net income attributable to MPC 4,218 The pro forma information includes adjustments to align accounting policies, an adjustment to depreciation expense to reflect the increased fair value of property, plant and equipment, increased amortization expense related to identifiable intangible assets and the related income tax effects. The pro forma information does not reflect the following • A $727 million effect on net income attributable to MPC related to purchase accounting related inventory effects and transaction-related costs as these charges do not have a continuing impact on the consolidated results. • The application of discontinued operations accounting for Speedway as the information required to apply discontinued operations accounting for periods prior to our ownership is not readily available. Acquisition of Terminal and Retail Locations in New York During the third quarter of 2019, we acquired a 900,000-barrel capacity light product and asphalt terminal and 33 NOCO Express retail stores in Buffalo, Syracuse and Rochester, New York, from NOCO Incorporated for total consideration of $135 million. Based on the final fair value estimates of assets acquired and liabilities assumed at the acquisition date, $38 million of the purchase price was allocated to property, plant and equipment, $3 million to inventory and $94 million to goodwill. Goodwill is tax deductible and represents the value expected to be created by geographically expanding our retail platform and the assembled workforce. The terminal is accounted for within the Refining & Marketing segment and the retail stores were accounted for within our former Retail segment. The amount of revenue and income from operations associated with the acquisition from the acquisition date to December 31, 2019 did not have a material impact on the consolidated financial statements. In addition, assuming the acquisition had occurred on January 1, 2018, the consolidated pro forma results would not have been materially different from the reported results. Acquisition of Express Mart During the fourth quarter of 2018, Speedway acquired 78 transportation fuel and convenience store locations from Petr-All Petroleum Consulting Corporation for total consideration of $266 million. These stores are located primarily in the Syracuse, Rochester and Buffalo markets in New York and operate under the Express Mart brand. Based on the final fair value estimates of assets acquired and liabilities assumed at the acquisition date, $97 million of the purchase price was allocated to property, plant and equipment, $9 million to inventory, $2 million to intangibles and $158 million to goodwill. Goodwill is tax deductible and represents the value expected to be created by geographically expanding our retail platform and the assembled workforce. The amount of revenue and income from operations associated with the acquisition from the acquisition date to December 31, 2018 did not have a material impact on the consolidated financial statements. In addition, assuming the acquisition had occurred on January 1, 2017, the consolidated pro forma results would not have been materially different from the reported results. Acquisition of Mt. Airy Terminal On September 26, 2018, MPLX acquired an eastern U.S. Gulf Coast export terminal (“Mt. Airy Terminal”) from Pin Oak Holdings, LLC for total consideration of $451 million. At the time of the acquisition, the terminal included tanks with 4 million barrels of third-party leased storage capacity and a dock with 120 mbpd of capacity. The Mt. Airy Terminal is located on the Mississippi River between New Orleans and Baton Rouge, near several Gulf Coast refineries, including our Garyville Refinery, and numerous rail lines and pipelines. The Mt. Airy Terminal is accounted for within the Midstream segment. In the first quarter of 2019, an adjustment to the initial purchase price was made for approximately $5 million related to the final settlement of the acquisition. This reduced the total purchase price to $446 million and resulted in $336 million of property, plant and equipment, $121 million of goodwill and the remainder being attributable to net liabilities assumed. Goodwill represents the significant growth potential of the terminal due to the multiple pipelines and rail lines which cross the property, the terminal’s position as an aggregation point for liquids growth in the region for both ocean-going vessels and inland barges, the proximity of the terminal to our Garyville refinery and other refineries in the region as well as the opportunity to construct an additional dock at the site. All of the goodwill recognized related to this transaction is tax deductible. The amount of revenue and income from operations associated with the acquisition from the terminal acquisition date to December 31, 2018 did not have a material impact on the consolidated financial statements. In addition, assuming the terminal acquisition had occurred on January 1, 2017, the consolidated pro forma results would not have been materially different from the reported results.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Variable Interest Entities	VARIABLE INTEREST ENTITIES Consolidated VIE We control MPLX through our ownership of its general partner. MPLX is a VIE because the limited partners do not have substantive kick-out or participating rights over the general partner. We are the primary beneficiary of MPLX because in addition to our significant economic interest, we also have the ability, through our ownership of the general partner, to control the decisions that most significantly impact MPLX. We therefore consolidate MPLX and record a noncontrolling interest for the interest owned by the public. We also record a redeemable noncontrolling interest related to MPLX’s Series A preferred units. The creditors of MPLX do not have recourse to MPC’s general credit through guarantees or other financial arrangements, except as noted. MPC has effectively guaranteed certain indebtedness of LOOP LLC (“LOOP”) and LOCAP LLC (“LOCAP”), in which MPLX holds an interest. See Note 29 for more information. The assets of MPLX can only be used to settle its own obligations and its creditors have no recourse to our assets, except as noted earlier. The following table presents balance sheet information for the assets and liabilities of MPLX, which are included in our balance sheets. (In millions) December 31, December 31, Assets Cash and cash equivalents $ 15 $ 15 Receivables, less allowance for doubtful accounts 478 615 Inventories 118 110 Other current assets 67 110 Assets held for sale 188 — Equity method investments 4,036 5,275 Property, plant and equipment, net 21,418 22,174 Goodwill 7,657 9,536 Right of use assets 309 365 Other noncurrent assets 1,006 1,323 Liabilities Accounts payable $ 468 $ 744 Payroll and benefits payable 4 5 Accrued taxes 76 80 Debt due within one year 764 9 Operating lease liabilities 63 66 Liabilities held for sale 101 — Other current liabilities 297 259 Long-term debt 19,375 19,704 Deferred income taxes 12 12 Long-term operating lease liabilities 244 302 Deferred credits and other liabilities 437 409 Non-Consolidated VIEs Crowley Coastal Partners In May 2016, Crowley Coastal Partners LLC (“Crowley Coastal Partners”) was formed to own an interest in both Crowley Ocean Partners LLC (“Crowley Ocean Partners”) and Crowley Blue Water Partners LLC (“Crowley Blue Water Partners”). We have determined that Crowley Coastal Partners is a VIE based on the terms of the existing financing arrangements for Crowley Blue Water Partners and Crowley Ocean Partners and the associated debt guarantees by MPC and Crowley. Our maximum exposure to loss at December 31, 2020 was $424 million, which includes our equity method investment in Crowley Coastal Partners and the debt guarantees provided to each of the lenders to Crowley Blue Water Partners and Crowley Ocean Partners. We are not the primary beneficiary of this VIE because we do not have the ability to control the activities that significantly influence the economic outcomes of the entity and, therefore, do not consolidate the entity. MPLX VIEs For those entities that have been deemed to be VIEs, neither MPLX nor any of its subsidiaries have been deemed to be the primary beneficiary due to voting rights on significant matters. While we have the ability to exercise influence through participation in the management committees which make all significant decisions, we have equal influence over each committee as a joint interest partner and all significant decisions require the consent of the other investors without regard to economic interest and as such we have determined that these entities should not be consolidated and apply the equity method of accounting with respect to our investments in each entity. Sherwood Midstream has been deemed the primary beneficiary of Sherwood Midstream Holdings due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. 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. We account for our ownership interest in each of these investments as an equity method investment. See Note 17 for ownership percentages and investment balances related to our non-consolidated VIEs.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS Transactions with related parties were as follows: (In millions) 2020 2019 2018 Sales to related parties $ 123 $ 91 $ 14 Purchases from related parties 738 763 610 Sales to related parties, which are included in sales and other operating revenues, consist primarily of refined product sales to certain of our equity affiliates.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings per Share	EARNINGS PER SHARE We compute basic earnings (loss) per share by dividing net income (loss) attributable to MPC less income allocated to participating securities by the weighted average number of shares of common stock outstanding. Since MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities, we have calculated our earnings (loss) per share using the two-class method. Diluted income (loss) per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive. (In millions, except per share data) 2020 2019 2018 Income (loss) from continuing operations, net of tax $ (11,182) $ 2,449 $ 2,933 Less: Net income (loss) attributable to noncontrolling interest (151) 618 826 Net income allocated to participating securities 1 1 1 Income (loss) from continuing operations available to common stockholders (11,032) 1,830 2,106 Income from discontinued operations, net of tax 1,205 806 673 Income (loss) available to common stockholders $ (9,827) $ 2,636 $ 2,779 Weighted average common shares outstanding: Basic 649 659 518 Effect of dilutive securities — 5 8 Diluted 649 664 526 Income (loss) available to common stockholders per share: Basic: Continuing operations $ (16.99) $ 2.78 $ 4.06 Discontinued operations 1.86 1.22 1.30 Net income (loss) per share $ (15.13) $ 4.00 $ 5.36 Diluted: Continuing operations $ (16.99) $ 2.76 $ 4.00 Discontinued operations 1.86 1.21 1.28 Net income (loss) per share $ (15.13) $ 3.97 $ 5.28 The following table summarizes the shares that were anti-dilutive, and therefore, were excluded from the diluted share calculation. (In millions) 2020 2019 2018 Shares issuable under stock-based compensation plans 11 3 —

Equity

Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Equity	EQUITY As of December 31, 2020, we had $2.96 billion of remaining share repurchase authorizations from our board of directors. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, tender offers, accelerated share repurchases or open market solicitations for shares, some of which may be effected through Rule 10b5-1 plans. The timing and amount of future repurchases will depend upon several factors, including market and business conditions, and such repurchases may be initiated, suspended or discontinued at any time. Total share repurchases were as follows for the respective periods: (In millions, except per share data) 2020 2019 2018 Number of shares repurchased — 34 47 Cash paid for shares repurchased $ — $ 1,950 $ 3,287 Average cost per share $ — $ 58.87 $ 69.46

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION On August 2, 2020, we entered into a definitive agreement to sell Speedway to 7-Eleven for $21 billion in cash, subject to certain adjustments based on the levels of cash, debt and working capital at closing and certain other items. In connection with the announced sale, we reassessed our organizational structure and management of segments. As a result of this assessment, we have made the following changes for all periods presented: • Speedway’s results are presented separately as discontinued operations. See Note 5 for related disclosures. • Refining & Marketing intersegment sales to Speedway that were previously eliminated in consolidation are reported as third party sales as we will continue to supply fuel to Speedway following its disposition. • The retained direct dealer business results, previously included in the Retail segment, are reported within the Refining & Marketing segment. • As a result of the above, we no longer present a separate Retail segment, which had included these two businesses. • Corporate costs are no longer allocated to Speedway under discontinued operations accounting. We have two reportable segments: Refining & Marketing and Midstream. Each of these segments is organized and managed based upon the nature of the products and services it offers. • Refining & Marketing – refines crude oil and other feedstocks at our refineries in the Gulf Coast, Mid-Continent and West Coast regions of the United States, purchases refined products and ethanol for resale and distributes refined products through transportation, storage, distribution and marketing services provided largely by our Midstream segment. We sell refined products to wholesale marketing customers domestically and internationally, to buyers on the spot market, to independent entrepreneurs who operate primarily Marathon ® branded outlets, through long-term supply contracts with direct dealers who operate locations mainly under the ARCO ® brand and to approximately 3,800 Speedway locations. • Midstream – transports, stores, distributes and markets crude oil and refined products principally for the Refining & Marketing segment via refining logistics assets, pipelines, terminals, towboats and barges; gathers, processes and transports natural gas; and gathers, transports, fractionates, stores and markets NGLs. The Midstream segment primarily reflects the results of MPLX. On October 1, 2018, we acquired Andeavor and its results are included in each of our segments from the date of the acquisition. Also, on February 1, 2018, we contributed certain refining logistics assets and fuels distribution services to MPLX. The results of these new businesses are reported in the Midstream segment prospectively from February 1, 2018, resulting in a net reduction to Refining & Marketing segment results and a net increase to Midstream segment results of the same amount. No effect was given to prior periods as these entities were not considered businesses prior to February 1, 2018. Segment income from operations represents income (loss) from operations attributable to the reportable segments. Corporate administrative expenses, except for those attributable to MPLX, and costs related to certain non-operating assets are not allocated to the Refining & Marketing segment. In addition, certain items that affect comparability (as determined by the chief operating decision maker (“CODM”)) are not allocated to the reportable segments. Assets by segment are not a measure used to assess the performance of the company by the CODM and thus are not reported in our disclosures. (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2020 Revenues: Third party (a) $ 66,180 $ 3,599 $ 69,779 Intersegment 67 4,839 4,906 Segment revenues $ 66,247 $ 8,438 $ 74,685 Segment income from operations $ (5,189) $ 3,708 $ (1,481) Supplemental Data Depreciation and amortization (b) 1,857 1,353 3,210 Capital expenditures and investments (c) 1,170 1,398 2,568 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2019 Revenues: Third party (a) $ 107,305 $ 3,843 $ 111,148 Intersegment 103 4,917 5,020 Segment revenues $ 107,408 $ 8,760 $ 116,168 Segment income from operation $ 2,856 $ 3,594 $ 6,450 Supplemental Data Depreciation and amortization (b) 1,780 1,267 3,047 Capital expenditures and investments (c) 2,045 3,290 5,335 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2018 Revenues: Third party (a) $ 82,755 $ 3,331 $ 86,086 Intersegment 66 3,329 3,395 Segment revenues $ 82,821 $ 6,660 $ 89,481 Segment income from operations $ 2,654 $ 2,752 $ 5,406 Supplemental Data Depreciation and amortization (b) 1,207 885 2,092 Capital expenditures and investments (c) 1,077 2,630 3,707 (a) Includes Refining & Marketing sales to Speedway (as discussed above) and related party sales. See Note 10 for additional information. (b) Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other items not allocated to segments. (c) Includes changes in capital expenditure accruals and investments in affiliates. The following reconciles segment income (loss) from operations to income (loss) from continuing operations before income taxes as reported in the consolidated statements of income: (In millions) 2020 2019 2018 Segment income (loss) from operations $ (1,481) $ 6,450 $ 5,406 Corporate (a) (800) (833) (528) Items not allocated to segments: Impairments (b) (9,741) (1,239) 9 Restructuring expenses (c) (367) — — Litigation 84 (22) — Gain on sale of assets 66 — — Transaction-related costs (d) (8) (153) (197) Equity method investment restructuring gains (e) — 259 — Income (loss) from continuing operations (12,247) 4,462 4,690 Net interest and other financial costs 1,365 1,229 993 Income (loss) from continuing operations before income taxes $ (13,612) $ 3,233 $ 3,697 (a) Corporate consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. Corporate includes corporate costs of $26 million, $28 million and $26 million for 2020, 2019 and 2018, respectively, that are no longer allocable to Speedway under discontinued operations accounting. (b) 2020 reflects impairments of goodwill, equity method investments and long lived assets. 2019 reflects impairments of goodwill and equity method investments. See Note 7. 2018 includes MPC’s share of gains from the sale of assets remaining from the Sandpiper pipeline project, which was cancelled and impaired in 2016. (c) See Note 4. (d) 2020 and 2019 includes costs incurred in connection with the Midstream strategic review and other related efforts. Both 2019 and 2018 include employee severance, retention and other costs related to the acquisition of Andeavor. Effective October 1, 2019, we have discontinued reporting Andeavor transaction-related costs as one year has passed since the acquisition and these costs are immaterial. Costs incurred in connection with the Speedway separation are included in discontinued operations. See Note 5. (e) Includes gains related to The Andersons Marathon Holdings LLC and Capline Pipeline Company LLC. See Note 17. The following reconciles segment capital expenditures and investments to total capital expenditures: (In millions) 2020 2019 2018 Segment capital expenditures and investments $ 2,568 $ 5,335 $ 3,707 Less investments in equity method investees 485 1,064 409 Plus items not allocated to segments: Corporate 80 100 77 Capitalized interest 106 137 80 Total capital expenditures (a) $ 2,269 $ 4,508 $ 3,455 (a) Includes changes in capital expenditure accruals. See Note 24 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows. Since we will continue to supply fuel to Speedway following its disposition, we have reported intersegment sales to Speedway, that were previously eliminated in consolidation, as third party sales in all periods presented. Sales to Speedway from the Refining & Marketing segment represented 11 percent, 12 percent and 13 percent of our total annual revenues for the years ended December 31, 2020, 2019 and 2018, respectively. See Note 23 for the disaggregation of our revenue by segment and product line. We do not have significant operations in foreign countries. Therefore, revenues in foreign countries and long-lived assets located in foreign countries, including property, plant and equipment and investments, are not material to our operations.

Net Interest and Other Financia

Net Interest and Other Financial Costs	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Net Interest and Other Financial Costs	NET INTEREST AND OTHER FINANCIAL COSTS Net interest and other financial costs were as follows: (In millions) 2020 2019 2018 Interest income $ (9) $ (40) $ (87) Interest expense 1,462 1,389 1,025 Interest capitalized (129) (158) (80) Pension and other postretirement non-service costs (a) 11 4 53 (Gain) loss on extinguishment of debt (9) — 64 Other financial costs 39 34 18 Net interest and other financial costs $ 1,365 $ 1,229 $ 993

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted by Congress and signed into law by President Trump in response to the COVID-19 pandemic. The CARES Act contained a net operating loss (“NOL”) carryback provision, which allowed MPC to carryback our 2020 taxable loss to 2015 and later years. The five-year NOL carryback is available for all businesses producing taxable losses in 2018 through 2020. Based on the NOL carryback, as provided by the CARES Act, we recorded an income tax receivable of $2.1 billion in other current assets to reflect our estimate of the tax refund we expect to receive from our 2020 federal tax return. The refund is expected to be received during the second half of 2021. In the absence of the CARES Act NOL legislation, businesses would account for taxable losses as deferred tax assets and could realize the deferred tax asset by offsetting the losses against taxable income earned in future periods. Due to the corporate tax rate change from 35 percent to the current 21 percent under the Tax Cut and Jobs Act of 2017, taxpayers may recover taxes paid in tax years before 2018 at a 35 percent federal income tax rate. The limitation on the percentage of taxable income that may be offset by the NOL, formerly 80 percent of income, was eliminated for years beginning before 2021. The provision (benefit) for income taxes from continuing operations consisted of: (In millions) 2020 2019 2018 Current: Federal $ (2,267) $ (52) $ 674 State and local 69 28 54 Foreign 9 1 22 Total current (2,189) (23) 750 Deferred: Federal 90 742 (119) State and local (347) 56 149 Foreign 16 9 (16) Total deferred (241) 807 14 Income tax provision (benefit) $ (2,430) $ 784 $ 764 A reconciliation of the federal statutory income tax rate to the effective tax rate applied to income (loss) from continuing operations before income taxes follows: 2020 2019 2018 Federal statutory rate 21 % 21 % 21 % State and local income taxes, net of federal income tax effects 2 2 5 Goodwill impairment (8) 5 — Noncontrolling interests — (4) (5) Legislation 4 — — Other (1) — — Effective tax rate applied to income (loss) from continuing operations before income taxes 18 % 24 % 21 % Deferred tax assets and liabilities resulted from the following: December 31, (In millions) 2020 2019 Deferred tax assets: Employee benefits $ 647 $ 693 Environmental remediation 95 99 Finance lease obligations 103 105 Debt financing 6 17 Operating lease liabilities 453 498 Net operating loss carryforwards 232 18 Foreign currency — 15 Tax credit carryforwards 19 14 Other 74 57 Total deferred tax assets 1,629 1,516 Deferred tax liabilities: Property, plant and equipment 3,195 3,301 Inventories 800 652 Investments in subsidiaries and affiliates 3,331 3,114 Goodwill and other intangibles 34 304 Right of use assets 451 498 Other 18 19 Total deferred tax liabilities 7,829 7,888 Net deferred tax liabilities $ 6,200 $ 6,372 The above table reflects reclassifications of December 31, 2019 balances from property, plant and equipment to finance lease obligations, operating lease liabilities, goodwill and other intangibles and right of use assets to correct the presentation of these deferred tax assets and liabilities that were previously presented as property, plant and equipment deferred tax liabilities. Net deferred tax liabilities were classified in the consolidated balance sheets as follows: December 31, (In millions) 2020 2019 Assets: Other noncurrent assets $ 3 $ 20 Liabilities: Deferred income taxes (a) 6,203 6,392 Net deferred tax liabilities $ 6,200 $ 6,372 (a) The deferred income tax assets and liabilities associated with discontinued operations remain in our balance sheet rather than being included in the carrying amount of assets and liabilities that are held for sale, as the sale is structured as a sale of assets. These discontinued operations deferred income tax assets and liabilities will be realized upon the sale of Speedway. At December 31, 2020 and 2019, federal operating loss carryforwards were $4 million and $7 million, respectively, which includes a mix of indefinite carryforward ability and expiration periods ranging from 2022 through 2037. As of December 31, 2020 and 2019, state and local operating loss carryforwards were $228 million and $11 million, respectively, which includes a mix of indefinite carryforward ability and expiration periods ranging from 2021 through 2042. As of December 31, 2020 and 2019, $11 million of valuation allowances have been recorded related to income taxes. A federal valuation allowance was established for December 31, 2020 and 2019, of $2 million, primarily due to the expected realizability of foreign tax credits. A state and local valuation allowance was established as of December 31, 2020 and 2019, of $9 million, based on expected realizability of state and local tax operating losses. MPC is continuously undergoing examination of its U.S. federal income tax returns by the Internal Revenue Service (“IRS”). Since 2012, we have continued to participate in the Compliance Assurance Process (“CAP”). CAP is a real-time audit of the U.S. Federal income tax return that allows the IRS, working in conjunction with MPC, to determine tax return compliance with the U.S. Federal tax law prior to filing the return. This program provides us with greater certainty about our tax liability for years under examination by the IRS. While Andeavor also underwent continual IRS examination, it did not participate in the CAP for tax periods prior to October 1, 2018. Andeavor and its subsidiaries’ IRS audits have been completed through the 2015 tax year. We believe adequate provisions have been established for potential tax in periods not closed to examination. Further, we are routinely involved in U.S. state income tax audits. We believe all other audits will be resolved with the amounts provided for these liabilities. As of December 31, 2020, our federal income tax returns remain subject to examination for years 2016 through 2019. As of December 31, 2020, we have various state and local income tax returns subject to examination for years 2006 through 2019, depending on jurisdiction. The following table summarizes the activity in unrecognized tax benefits: (In millions) 2020 2019 2018 January 1 balance $ 32 $ 211 $ 19 Additions for tax positions of prior years 12 2 — Reductions for tax positions of prior years (18) (2) (5) Settlements (3) (19) — Statute of limitations — (160) (12) Acquired from Andeavor — — 209 December 31 balance $ 23 $ 32 $ 211 If the unrecognized tax benefits as of December 31, 2020 were recognized, $14 million would affect our effective income tax rate. There were $9 million of uncertain tax positions as of December 31, 2020 for which it is reasonably possible that the amount of unrecognized tax benefits would significantly decrease during the next twelve months. For tax years 2009 and 2010, Andeavor had asserted a federal income tax claim for $159 million from the income tax effect of the receipt of the ethanol blender’s excise tax credit, for which the tax benefit was not recorded. The statute of limitations for the IRS appeal process expired during the fourth quarter 2019 since the ability to obtain a refund was remote. Pursuant to our tax sharing agreement with Marathon Oil, the unrecognized tax benefits related to pre-spinoff operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and we have indemnified Marathon Oil accordingly. See Note 29 for indemnification information. Interest and penalties related to income taxes are recorded as part of the provision for income taxes. Such interest and penalties were net expenses (benefits) of $(19) million, $(2) million and $1 million in 2020, 2019 and 2018, respectively. As of December 31, 2020 and 2019, $(5) million and $7 million of interest and penalties were accrued related to income taxes.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Inventories	INVENTORIES December 31, (In millions) 2020 2019 Crude oil $ 2,588 $ 3,472 Refined products 4,478 5,359 Materials and supplies 933 973 Total $ 7,999 $ 9,804 The LIFO method accounted for 88 percent and 90 percent of total inventory value at December 31, 2020 and 2019, respectively. There was no excess of replacement or current cost over our stated LIFO cost as of December 31, 2020. Current acquisition costs were estimated to exceed the LIFO inventory value by $787 million at December 31, 2019 The cost of inventories of crude oil and refined products is determined primarily under the LIFO method. During 2020, we recorded a $561 million charge to reflect LIFO liquidations for our crude oil and refined product inventories. The costs of inventories in the historical LIFO layers which were liquidated were higher than current costs, which resulted in the charge to cost of revenues. There were no liquidations of LIFO inventories in 2019 and 2018. .

Equity Method Investments

Equity Method Investments	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	EQUITY METHOD INVESTMENTS The Andersons Marathon Holdings LLC Effective October 1, 2019, The Andersons, Inc. and MPC contributed jointly owned equity interests in three ethanol entities into a new legal entity, The Andersons Marathon Holdings LLC (“TAMH”). Concurrently, The Andersons, Inc. contributed a wholly-owned ethanol facility to TAMH. In accordance with ASC 845, we derecognized the historical cost of our equity method investments in the legacy entities amounting to $123 million and recognized the new equity method investment in TAMH at fair value. We used a combination of market, income and cost approaches to determine the fair value of our ownership interest in TAMH with more reliance on the market and income approaches. The estimated cash flows used in the income approach were discounted using a weighted average cost of capital estimate and the market approach utilized EBITDA and capacity multiples for similar companies and transactions. This is a nonrecurring fair value measurement and is recognized in Level 3 of the fair value hierarchy. We estimated the fair value of our ownership interest to be $175 million. The excess of the estimated fair value of our ownership interest over the carrying value of the derecognized net assets resulted in a $52 million non-cash net gain recorded as a net gain on disposal of assets in the accompanying consolidated statements of income. Capline LLC During the three months ended March 31, 2019, we executed agreements with Capline Pipeline Company LLC (“Capline LLC”) to contribute our 33 percent undivided interest in the Capline pipeline system in exchange for a 33 percent ownership interest in Capline LLC. In connection with our execution of these agreements, Capline LLC initiated a binding open season for southbound service from Patoka, Illinois to St. James, Louisiana or Liberty, Mississippi with an additional origination point at Cushing, Oklahoma. Service from Cushing, Oklahoma is part of a joint tariff with Diamond pipeline. In accordance with ASC 810, we derecognized our undivided interest amounting to $143 million of net assets and recognized the Capline LLC ownership interest we received at fair value. We used an income approach to determine the fair value of our ownership interest under a Monte Carlo simulation method. We estimated the fair value of our ownership interest to be $350 million. This is a nonrecurring fair value measurement and is categorized in Level 3 of the fair value hierarchy. The Monte Carlo simulation inputs include ranges of tariff rates, operating volumes, operating cost and capital expenditure assumptions. The estimated cash flows were discounted using a Monte Carlo market participant weighted average cost of capital estimate. None of the inputs to the Monte Carlo simulation are individually significant. The excess of the estimated fair value of our ownership interest over the carrying value of the derecognized net assets resulted in a $207 million non-cash net gain recorded as a net gain on disposal of assets in the accompanying consolidated statements of income. As the Capline system is currently idled, Capline LLC is unable to fund its operations without financial support from its equity owners and is a VIE. MPC is not deemed to be the primary beneficiary, due to our inability to unilaterally control significant decision-making rights. Our maximum exposure to loss as a result of our involvement with Capline LLC includes our equity investment, any additional capital contribution commitments and any operating expenses incurred by Capline LLC in excess of compensation received for performance of the operating services. Investments in Equity Method Affiliates Ownership as of Carrying value at December 31, December 31, (Dollars in millions) VIE 2020 2020 2019 Refining & Marketing The Andersons Marathon Holdings LLC 50% $ 159 $ 177 Watson Cogeneration Company 51% 25 26 Refining & Marketing Total $ 184 $ 203 Midstream MPLX Andeavor Logistics Rio Pipeline LLC X 67% $ 194 $ 202 Centrahoma Processing LLC 40% 145 153 Explorer Pipeline Company 25% 72 83 Illinois Extension Pipeline Company, L.L.C 35% 254 265 LOOP LLC 41% 252 238 MarEn Bakken Company LLC 25% 465 481 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. X 67% 307 302 MarkWest Utica EMG, L.L.C. X 57% 698 1,984 Minnesota Pipe Line Company, LLC 17% 188 190 Rendezvous Gas Services, L.L.C. X 78% 159 170 Sherwood Midstream Holdings LLC X 51% 148 157 Sherwood Midstream LLC X 50% 557 537 Whistler Pipeline LLC X 38% 185 134 Wink to Webster Pipeline LLC (a) X —% — 126 W2W Holdings LLC (a) X 50% 72 — Other (b) X 340 253 MPLX Total $ 4,036 $ 5,275 MPC-Retained Capline Pipeline Company LLC X 33% $ 390 $ 374 Crowley Coastal Partners, LLC X 50% 190 188 Gray Oak Pipeline, LLC 25% 342 298 LOOP LLC 10% 63 59 South Texas Gateway Terminal LLC 25% 168 85 Other (b) X 49 86 MPC-Retained Total $ 1,202 $ 1,090 Midstream Total $ 5,238 $ 6,365 Total $ 5,422 $ 6,568 (a) During 2020, MPLX contributed its ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC. (b) Some investments included within “Other” have been deemed to be VIEs. Summarized financial information for all equity method investments in affiliated companies, combined, was as follows: (In millions) 2020 2019 2018 Income statement data: Revenues and other income $ 3,013 $ 3,282 $ 3,092 Income from operations 599 1,176 1,105 Net income 454 987 972 Balance sheet data – December 31: Current assets $ 1,298 $ 1,195 Noncurrent assets 17,697 16,362 Current liabilities 754 997 Noncurrent liabilities 4,736 2,769 As of December 31, 2020, the carrying value of our equity method investments was $361 million higher than the underlying net assets of investees. This basis difference is being amortized into net income over the remaining estimated useful lives of the underlying net assets, except for $199 million of excess related to goodwill and other non-depreciable assets. Dividends and partnership distributions received from equity method investees (excluding distributions that represented a return of capital previously contributed) were $577 million, $569 million and $458 million in 2020, 2019 and 2018. See Note 7 for information regarding impairments of equity method investments.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT (In millions) Estimated December 31, 2020 2019 Refining & Marketing (a) 4 -30 years $ 30,306 $ 29,101 Midstream 1 -61 years 27,677 27,193 Corporate 4 - 40 years 1,356 1,292 Total 59,339 57,586 Less accumulated depreciation (b) 20,304 16,716 Property, plant and equipment, net $ 39,035 $ 40,870 (a) Recast to include the direct dealer business. See Note 13 for additional information. (b) The December 31, 2020 balance includes property, plant and equipment impairment charges recorded during 2020. See Note 7 for additional information. Property, plant and equipment includes gross assets acquired under finance leases of $819 million and $740 million at December 31, 2020 and 2019, respectively, with related amounts in accumulated depreciation of $272 million and $215 million at December 31, 2020 and 2019. Property, plant and equipment includes construction in progress of $1.83 billion and $3.12 billion at December 31, 2020 and 2019, respectively, which primarily relates to capital projects at our refineries and midstream facilities.

Goodwill and Intangibles

Goodwill and Intangibles	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	GOODWILL AND INTANGIBLES Goodwill Management 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. In 2020 and 2019, we recorded impairments of goodwill as outlined in Note 7. There were no other impairments of goodwill required based on our annual test of goodwill in 2020 and 2019. The changes in the carrying amount of goodwill for 2019 and 2020 were as follows: (In millions) Refining & Marketing (a) Midstream Total Balance at January 1, 2019 $ 5,511 $ 10,323 $ 15,834 Acquisitions 38 — 38 Purchase price allocation adjustments 584 408 992 Impairments (b) — (1,197) (1,197) Dispositions — (17) (17) Balance at December 31, 2019 $ 6,133 $ 9,517 $ 15,650 Transfers 8 (8) — Impairments (b) (5,580) (1,814) (7,394) Balance at December 31, 2020 $ 561 $ 7,695 $ 8,256 (a) Recast to include the direct dealer business. See Note 13 for additional information. (b) See Note 7. Intangible Assets Our definite lived intangible assets as of December 31, 2020 and 2019 are as shown below. December 31, 2020 December 31, 2019 (In millions) Gross Accumulated Amortization Net Gross Accumulated Amortization Net Customer contracts and relationships $ 3,359 $ 1,119 $ 2,240 $ 3,271 $ 612 $ 2,659 Brand rights and tradenames 100 35 65 100 20 80 Royalty agreements 133 87 46 133 78 55 Other 36 27 9 36 24 12 Total $ 3,628 $ 1,268 $ 2,360 $ 3,540 $ 734 $ 2,806 At both December 31, 2020 and 2019, we had indefinite lived intangible assets $71 million, which are emission allowance credits. Amortization expense for 2020 and 2019 was $336 million and $357 million, respectively. Estimated future amortization expense for the next five years related to the intangible assets at December 31, 2020 is as follows: (In millions) 2021 $ 347 2022 346 2023 330 2024 277 2025 257

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Values – Recurring The following tables present assets and liabilities accounted for at fair value on a recurring basis as of December 31, 2020 and 2019 by fair value hierarchy level. We have elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty, including any related cash collateral as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the following tables. December 31, 2020 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 82 $ 6 $ — $ (80) $ 8 $ 31 Liabilities: Commodity contracts $ 81 $ 10 $ — $ (91) $ — $ — Embedded derivatives in commodity contracts — — 63 — 63 — December 31, 2019 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 57 $ 6 $ — $ (55) $ 8 $ 73 Liabilities: Commodity contracts $ 95 $ 11 $ — $ (106) $ — $ — Embedded derivatives in commodity contracts — — 60 — 60 — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of December 31, 2020, cash collateral of $11 million was netted with mark-to-market liabilities. As of December 31, 2019, cash collateral of $51 million was netted with mark-to-market derivative liabilities. (b) We have no derivative contracts which are subject to master netting arrangements reflected gross on the balance sheet. Commodity derivatives in Level 1 are exchange-traded contracts for crude oil and refined products measured at fair value with a market approach using the close-of-day settlement prices for the market. Commodity derivatives are covered under master netting agreements with an unconditional right to offset. Collateral deposits in futures commission merchant accounts covered by master netting agreements related to Level 1 commodity derivatives are classified as Level 1 in the fair value hierarchy. Level 2 instruments are valued based on quoted prices for similar assets and liabilities in active markets, and inputs other than quoted prices, such as liquidity, that are observable for the asset or liability. Commodity derivatives in Level 2 are OTC contracts, which are valued using market quotations from independent price reporting agencies, third-party brokers and commodity exchange price curves that are corroborated with market data. Level 3 instruments include embedded derivatives in commodity contracts. The embedded derivative liability relates to a natural gas purchase agreement embedded in a keep‑whole processing agreement. The fair value calculation for these Level 3 instruments at December 31, 2020 used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.47 to $1.09 per gallon with a weighted average of $0.59 per gallon and (2) the probability of renewal of 100 percent for the first and second five-year term of the natural gas purchase agreement and the related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability. The following is a reconciliation of the beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. (In millions) 2020 2019 Beginning balance $ 60 $ 61 Unrealized and realized losses included in net income 9 5 Settlements of derivative instruments (6) (6) Ending balance $ 63 $ 60 The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: $ 4 $ 5 See Note 21 for the income statement impacts of our derivative instruments. Fair Values – Reported We believe the carrying value of our other financial instruments, including cash and cash equivalents, receivables, accounts payable and certain accrued liabilities approximate fair value. Our fair value assessment incorporates a variety of considerations, including the short-term duration of the instruments and the expected insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. The borrowings under our revolving credit facilities and term loan facility, which include variable interest rates, approximate fair value. The fair value of our fixed and floating rate long-term debt is based on prices from recent trade activity and is categorized in Level 3 of the fair value hierarchy. The carrying and fair values of our debt were approximately $31.1 billion and $34.9 billion at December 31, 2020, respectively, and approximately $28.3 billion and $30.1 billion at December 31, 2019, respectively. These carrying and fair values of our debt exclude the unamortized issuance costs which are netted against our total debt.

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2020
Summary of Derivative Instruments [Abstract]
Derivatives	DERIVATIVES For further information regarding the fair value measurement of derivative instruments, including any effect of master netting agreements or collateral, see Note 20. See Note 2 for a discussion of the types of derivatives we use and the reasons for them. We do not designate any of our commodity derivative instruments as hedges for accounting purposes. The following table presents the fair value of derivative instruments as of December 31, 2020 and 2019 and the line items in the balance sheets in which the fair values are reflected. The fair value amounts below are presented on a gross basis and do not reflect the netting of asset and liability positions permitted under the terms of our master netting arrangements including cash collateral on deposit with, or received from, brokers. We offset the recognized fair value amounts for multiple derivative instruments executed with the same counterparty in our financial statements when a legal right of offset exists. As a result, the asset and liability amounts below will not agree with the amounts presented in our consolidated balance sheets. (In millions) December 31, 2020 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 88 $ 91 Other current liabilities (a) — 7 Deferred credits and other liabilities (a) — 56 (In millions) December 31, 2019 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 63 $ 106 Other current liabilities (a) — 5 Deferred credits and other liabilities (a) — 55 (a) Includes embedded derivatives. The table below summarizes open commodity derivative contracts for crude oil, refined products and blending products as of December 31, 2020. Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 81.9% 17,474 11,197 Refined products 89.0% 13,923 9,354 Blending products 100.0% 3,206 3,987 Soybean oil 100.0% 558 1,117 (a) Included in exchange-traded are spread contracts in thousands of barrels: Refined products - 935 long and 455 short The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income: (In millions) Gain (Loss) Income Statement Location 2020 2019 2018 Sales and other operating revenues $ 72 $ (19) $ 13 Cost of revenues 34 (77) (59) Other income 1 — — Total $ 107 $ (96) $ (46)

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	DEBT Our outstanding borrowings at December 31, 2020 and 2019 consisted of the following: (In millions) December 31, December 31, Marathon Petroleum Corporation: Commercial paper $ 1,024 $ — Senior notes 9,849 8,474 Notes payable 1 1 Finance lease obligations 634 574 MPLX LP: Bank revolving credit facility 175 — Term loan facility — 1,000 Senior notes 20,350 19,100 Finance lease obligations 11 19 Total debt $ 32,044 $ 29,168 Unamortized debt issuance costs (154) (134) Unamortized (discount) premium, net (306) (310) Amounts due within one year (2,854) (704) Total long-term debt due after one year $ 28,730 $ 28,020 Commercial Paper On February 26, 2016, we established a commercial paper program that allows us to have a maximum of $2 billion in commercial paper outstanding, with maturities up to 397 days from the date of issuance. We do not intend to have outstanding commercial paper borrowings in excess of available capacity under our bank revolving credit facilities. MPC Senior Notes December 31, (In millions) 2020 2019 Marathon Petroleum Corporation: Senior notes, 3.400% due December 2020 $ — $ 650 Senior notes, 5.125% due March 2021 1,000 1,000 Senior notes, 5.375% due October 2022 — 337 Senior notes, 4.500% due May 2023 1,250 — Senior notes, 4.750% due December 2023 614 614 Senior notes, 5.125% due April 2024 241 241 Senior notes, 3.625% due September 2024 750 750 Senior notes, 4.700% due May 2025 1,250 — Senior notes, 5.125% due December 2026 719 719 Senior notes, 3.800% due April 2028 496 496 Senior notes, 6.500% due March 2041 1,250 1,250 Senior notes, 4.750% due September 2044 800 800 Senior notes, 5.850% due December 2045 250 250 Senior notes, 4.500% due April 2048 498 498 Andeavor senior notes, 3.800% - 5.375% due 2022 - 2048 331 469 Senior notes, 5.000%, due September 2054 400 400 Total $ 9,849 $ 8,474 On April 27, 2020, we issued $2.5 billion aggregate principal amount of senior notes in a public offering, consisting of $1.25 billion aggregate principal amount of 4.500% unsecured senior notes due May 2023 and $1.25 billion aggregate principal amount of 4.700% unsecured senior notes due May 2025. MPC used the net proceeds from this offering to repay amounts outstanding under its five-year revolving credit facility. On October 1, 2020, all of the $475 million outstanding aggregate principal amount of 5.375% senior notes due October 2022, including the portion of such notes for which Andeavor was the obligor, were redeemed at a price equal to par. On November 15, 2020, all of the $650 million outstanding aggregate principal amount of 3.400% senior notes due December 2020 were redeemed at a price equal to par. Interest on each series of senior notes is payable semi-annually in arrears. The MPC senior notes are unsecured and unsubordinated obligations of MPC and rank equally with all of MPC’s other existing and future unsecured and unsubordinated indebtedness. The MPC senior notes are non-recourse and structurally subordinated to the indebtedness of our subsidiaries, including the outstanding indebtedness of Andeavor, MPLX and ANDX. The Andeavor senior notes are unsecured, unsubordinated obligations of Andeavor and are non-recourse to MPC and any of MPC’s subsidiaries other than Andeavor. MPLX Term Loan Facility The $1.0 billion of outstanding borrowings under the MPLX term loan facility was repaid during 2020 with net proceeds from the issuance of MPLX senior notes discussed below. MPLX Senior Notes December 31, (In millions) 2020 2019 MPLX LP: Floating rate notes due September 2021 $ — $ 1,000 Floating rate notes due September 2022 1,000 1,000 Senior notes, 6.250% due October 2022 — 266 Senior notes, 3.500% due December 2022 486 486 Senior notes, 3.375% due March 2023 500 500 Senior notes, 4.500% due July 2023 989 989 Senior notes, 6.375% due May 2024 — 381 Senior notes, 4.875% due December 2024 1,149 1,149 Senior notes, 5.250% due January 2025 708 708 Senior notes, 4.000% due February 2025 500 500 Senior notes, 4.875% due June 2025 1,189 1,189 MarkWest senior notes, 4.500% - 4.875% due 2023 - 2025 23 23 Senior notes, 1.750% due March 2026 1,500 — Senior notes, 4.125% due March 2027 1,250 1,250 Senior notes, 4.250% due December 2027 732 732 Senior notes, 4.000% due March 2028 1,250 1,250 Senior notes, 4.800% due February 2029 750 750 Senior notes, 2.650% due August 2030 1,500 — Senior notes, 4.500% due April 2038 1,750 1,750 Senior notes, 5.200% due March 2047 1,000 1,000 Senior notes, 5.200% due December 2047 487 487 ANDX senior notes, 3.500% - 5.250% due 2022 - 2047 87 190 Senior notes, 4.700% due April 2048 1,500 1,500 Senior notes, 5.500% due February 2049 1,500 1,500 Senior notes, 4.900% due April 2058 500 500 Total $ 20,350 $ 19,100 2020 Activity On August 18, 2020, MPLX issued $3.0 billion aggregate principal amount of senior notes in a public offering, consisting of $1.5 billion aggregate principal amount of 1.750% senior notes due March 2026 and $1.5 billion aggregate principal amount of 2.650% senior notes due August 2030. The net proceeds were used to repay $1.0 billion of outstanding borrowings under the MPLX term loan agreement, to repay the $1.0 billion aggregate principal amount of floating rate senior notes due September 2021, to redeem all of the $300 million aggregate principal amount of MPLX’s 6.250% senior notes due October 2022 and to redeem the $450 million aggregate principal amount of 6.375% senior notes due May 2024, including the portion of such notes issued by ANDX. The remaining net proceeds were used for general business purposes. On December 29, 2020, MPLX announced the redemption of all the $750 million outstanding aggregate principal amount of 5.250% senior notes due January 2025, including the portion of such notes issued by ANDX. The notes were redeemed on January 15, 2021 at a price equal to 102.625% of the principal amount. These notes are included in long-term debt due within one year in our consolidated balance sheet as of December 31, 2020. 2019 Activity On September 9, 2019, MPLX issued $2.0 billion aggregate principal amount of floating rate senior notes in a public offering, consisting of $1.0 billion aggregate principal amount of notes due September 2021 and $1.0 billion aggregate principal amount of notes due September 2022. Net proceeds from the issuance of the floating rate senior notes were used to repay MPLX’s existing indebtedness and/or for general business purposes. The interest rate applicable to the floating rate senior notes due September 2021 is LIBOR plus 0.9% per annum while the interest rate applicable to the floating rate senior notes due September 2022 is LIBOR plus 1.1% per annum. Interest is payable in March, June, September and December, commencing on December 9, 2019. Both series of floating rate notes are callable, in whole or in part, at par plus accrued and unpaid interest at any time on or after September 10, 2020. In connection with MPLX’s acquisition of ANDX on July 30, 2019, MPLX assumed ANDX’s outstanding senior notes, which had an aggregate principal amount of $3.75 billion, with interest rates ranging from 3.500% to 6.375% and maturity dates ranging from 2019 to 2047. On September 23, 2019, approximately $3.06 billion aggregate principal amount of ANDX’s outstanding senior notes were exchanged for new unsecured senior notes issued by MPLX having the same maturity and interest rates as the ANDX senior notes in an exchange offer and consent solicitation undertaken by MPLX, leaving approximately $690 million aggregate principal of outstanding senior notes issued by ANDX. Of this, $500 million was related to the 5.500% unsecured senior notes due 2019. The principal amount of $500 million and accrued interest of $14 million was paid on October 15, 2019, which included interest through the payoff date. Interest on each series of MPLX fixed rate senior notes is payable semi-annually in arrears. The MPLX senior notes are unsecured, unsubordinated obligations of MPLX and are non-recourse to MPC and its subsidiaries other than MPLX and MPLX GP LLC, as the general partner of MPLX except as otherwise noted. Schedule of Maturities Principal maturities of long-term debt, excluding finance lease obligations, as of December 31, 2020 for the next five years are as follows: (In millions) 2021 $ 1,750 2022 1,500 2023 3,600 2024 2,376 2025 2,950 Available Capacity under our Facilities as of December 31, 2020 (Dollars in millions) Total Outstanding Outstanding Available Weighted Expiration MPC, excluding MPLX MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2021 MPC 364-day bank revolving credit facility 1,000 — — 1,000 — April 2021 MPC bank revolving credit facility (a) 5,000 — 1 4,999 — October 2023 MPC trade receivables securitization facility (b) 750 — — 750 — July 2021 MPLX MPLX bank revolving credit facility (c) 3,500 175 — 3,325 1.36 July 2024 (a) Borrowed $4.225 billion and repaid $4.225 billion during the year ended December 31, 2020. (b) Borrowed $3.550 billion and repaid $3.550 billion during the year ended December 31, 2020. Availability under our $750 million trade receivables facility is a function of eligible trade receivables, which will be lower in a sustained lower price environment for refined products. (c) Borrowed $3.815 billion and repaid $3.640 billion during the year ended December 31, 2020. MPC Revolving Credit Agreements On August 28, 2018, in connection with the Andeavor acquisition, MPC entered into a credit agreement with a syndicate of lenders providing for a $5.0 billion five-year revolving credit facility that expires in 2023. The five-year credit agreement became effective on October 1, 2018. On September 23, 2020, MPC entered into a 364-day credit agreement with a syndicate of lenders. This revolving credit agreement provides for a $1.0 billion unsecured revolving credit facility that matures in September 2021, and replaces a similar 364-day revolving credit agreement that expired on September 28, 2020. On April 27, 2020, MPC entered into an additional 364-day revolving credit agreement that provides for a $1.0 billion unsecured revolving credit facility that matures in April 2021. In February 2021, we elected to terminate this credit agreement. This facility provided us with additional liquidity and financial flexibility during the then ongoing commodity price and demand downturn. There were no borrowings under this credit facility, and we determined that the incremental borrowing capacity of the facility was no longer necessary. We do not intend to replace this facility. We incurred no early termination fees as a result of the early termination of this credit agreement. MPC has an option under its $5.0 billion five-year credit agreement to increase the aggregate commitments by up to an additional $1.0 billion, subject to, among other conditions, the consent of the lenders whose commitments would be increased. In addition, MPC may request up to two one-year extensions of the maturity date of the five-year credit agreement subject to, among other conditions, the consent of lenders holding a majority of the commitments, provided that the commitments of any non-consenting lenders will terminate on the then-effective maturity date. The five-year credit agreement includes sub-facilities for swing-line loans of up to $250 million and letters of credit of up to $2.2 billion (which may be increased to up to $3.0 billion upon receipt of additional letter of credit issuing commitments). Borrowings under the MPC credit agreements bear interest, at our election, at either the Adjusted LIBO Rate or the Alternate Base Rate (both as defined in the MPC credit agreements), plus an applicable margin. We are charged various fees and expenses under the MPC credit agreements, including administrative agent fees, commitment fees on the unused portion of the commitments and fees related to issued and outstanding letters of credit. The applicable margins to the benchmark interest rates and the commitment fees payable under the MPC credit agreements fluctuate based on changes, if any, to our credit ratings. The MPC credit agreements contain certain representations and warranties, affirmative and restrictive covenants and events of default that we consider to be usual and customary for arrangements of this type, including a financial covenant that requires us to maintain a ratio of Consolidated Net Debt to Total Capitalization (each as defined in the MPC credit agreements) of no greater than 0.65 to 1.00 as of the last day of each fiscal quarter. The covenants also restrict, among other things, our ability and/or the ability of certain of our subsidiaries to incur debt, create liens on assets or enter into transactions with affiliates. As of December 31, 2020, we were in compliance with the covenants contained in the MPC credit agreements. Trade Receivables Securitization Facility The trade receivables facility consists of our wholly-owned subsidiaries selling or contributing on an on-going basis all of their trade receivables, together with all related security and interests in the proceeds thereof, without recourse, to another wholly-owned, bankruptcy-remote special purpose subsidiary, MPC Trade Receivables Company LLC (“TRC”), in exchange for a combination of cash, equity and/or borrowings under a subordinated note issued by TRC. TRC, in turn, has the ability to sell undivided ownership interests in qualifying trade receivables, together with all related security and interests in the proceeds thereof, without recourse, to the purchasing group in exchange for cash proceeds. The trade receivables facility also provides for the issuance of letters of credit up to $750 million, provided that the aggregate credit exposure of the purchasing group, including outstanding letters of credit, may not exceed the lesser of $750 million or the balance of qualifying trade receivables at any one time. To the extent that TRC retains an ownership interest in the receivables it has purchased or received under the facility, such interest will be included in our consolidated financial statements solely as a result of the consolidation of the financial statements of TRC with those of MPC. The receivables sold or contributed to TRC are available first and foremost to satisfy claims of the creditors of TRC and are not available to satisfy the claims of creditors of MPC. TRC has granted a security interest in all of its assets to the purchasing group to secure its obligations under the Receivables Purchase Agreement. Proceeds from the sale of undivided percentage ownership interests in qualifying receivables under the trade receivables facility are reflected as debt on our consolidated balance sheet. We remain responsible for servicing the receivables sold to the purchasing group. TRC pays floating-rate interest charges and usage fees on amounts outstanding under the trade receivables facility, if any, unused fees on the portion of unused commitments and certain other fees related to the administration of the facility and letters of credit that are issued and outstanding under the trade receivables facility. The receivables purchase agreement and receivables sale agreement contain representations and covenants that we consider usual and customary for arrangements of this type. Trade receivables are subject to customary criteria, limits and reserves before being deemed to qualify for sale by TRC pursuant to the trade receivables facility. In addition, further purchases of qualified trade receivables under the trade receivables facility are subject to termination, and TRC may be subject to default fees, upon the occurrence of certain amortization events that are included in the receivables purchase agreement, all of which we consider to be usual and customary for arrangements of this type. As of December 31, 2020, we were in compliance with the covenants contained in the receivables purchase agreement and receivables sale agreement. MPLX Credit Agreement Upon the completion of the merger of MPLX and ANDX on July 30, 2019, the MPLX bank revolving credit facility was amended and restated to increase the borrowing capacity to $3.5 billion and to extend the maturity date to July 30, 2024. The ANDX revolving and dropdown credit facilities were terminated and all outstanding balances were repaid and funded with borrowings under the amended and restated MPLX $3.5 billion bank revolving credit facility. The MPLX credit agreement includes letter of credit issuing capacity of up to approximately $300 million and swingline loan capacity of up to $150 million. The revolving borrowing capacity may be increased by up to an additional $1.0 billion, subject to certain conditions, including the consent of the lenders whose commitments would increase. Borrowings under the MPLX credit agreement bear interest, at MPLX’s election, at the Adjusted LIBO Rate or the Alternate Base Rate (both as defined in the MPLX credit agreement) plus an applicable margin. MPLX is charged various fees and expenses in connection with the agreement, including administrative agent fees, commitment fees on the unused portion of the commitments and fees with respect to issued and outstanding letters of credit. The applicable margins to the benchmark interest rates and the commitment fees payable under the MPLX credit agreement fluctuate based on changes, if any, to MPLX’s credit ratings. The MPLX credit agreement contains certain representations and warranties, affirmative and restrictive covenants and events of default that we consider to be usual and customary for an agreement of this type, 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 for certain acquisitions completed and capital projects undertaken during the relevant period. The covenants also restrict, among other things, MPLX’s ability and/or the ability of certain of its subsidiaries to incur debt, create liens on assets and enter into transactions with affiliates. As of December 31, 2020, MPLX was in compliance with the covenants contained in the MPLX credit agreement.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE As discussed in Notes 1 and 13, the presentation of Refining & Marketing segment revenues reflects changes associated with the expected sale of Speedway and our new reportable segments. The following table presents our revenues disaggregated by segment and product line: (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2020 Refined products $ 61,648 $ 641 $ 62,289 Crude oil 4,023 — 4,023 Midstream services and other 509 2,958 3,467 Sales and other operating revenues $ 66,180 $ 3,599 $ 69,779 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2019 Refined products $ 102,316 $ 818 $ 103,134 Crude oil 4,402 — 4,402 Midstream services and other 587 3,025 3,612 Sales and other operating revenues $ 107,305 $ 3,843 $ 111,148 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2018 Refined products $ 78,952 $ 945 $ 79,897 Crude oil 3,345 — 3,345 Midstream services and other 458 2,386 2,844 Sales and other operating revenues $ 82,755 $ 3,331 $ 86,086 We do not disclose information on the future performance obligations for any contract with expected duration of one year or less at inception. As of December 31, 2020, we do not have future performance obligations that are material to future periods. Receivables

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION (In millions) 2020 2019 2018 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 1,235 $ 1,168 $ 887 Net income taxes paid to (received from) taxing authorities (179) 491 424 Cash paid for amounts included in the measurement of lease liabilities Payments on operating leases (a) 651 642 — Interest payments under finance lease obligations (a) 25 28 — Net cash provided by financing activities included: Principal payments under finance lease obligations (a) 66 48 — Non-cash investing and financing activities: Capital leases — — 172 Right of use assets obtained in exchange for new operating lease obligations (a) 343 329 — Right of use assets obtained in exchange for new finance lease obligations (a) 110 80 — Contribution of assets (b) — 266 — Fair value of assets acquired (c) — 525 — Acquisition: Fair value of MPC shares issued — — 19,766 Fair value of converted equity awards — — 203 (a) Disclosure added in 2019 following the adoption of ASC 842. (b) 2019 includes the contribution of net assets to TAMH and Capline LLC. See Note 17. (c) 2019 includes the recognition of TAMH and Capline LLC equity method investments. See Note 17. (In millions) December 31, December 31, Cash and cash equivalents (a) $ 415 $ 1,393 Restricted cash (b) 1 2 Cash, cash equivalents and restricted cash $ 416 $ 1,395 (a) Excludes $140 million and $134 million of cash included in assets held for sale representing Speedway store cash. (b) The restricted cash balance is included within other current assets on the consolidated balance sheets. 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 expenditures: (In millions) 2020 2019 2018 Additions to property, plant and equipment per the consolidated statements of cash flows $ 2,787 $ 4,810 $ 3,179 Asset retirement expenditures — 1 8 Increase (decrease) in capital accruals (518) (303) 268 Total capital expenditures $ 2,269 $ 4,508 $ 3,455

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2018 $ (132) $ (23) $ 2 $ 9 $ (144) Other comprehensive income (loss) before reclassifications, net of tax of $(52) (71) (92) — 1 (162) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (45) — — — (45) – actuarial loss (a) 22 (1) — — 21 – settlement loss (a) 9 — — — 9 Other — — (1) (4) (5) Tax effect 5 — — 1 6 Other comprehensive loss (80) (93) (1) (2) (176) Balance as of December 31, 2019 $ (212) $ (116) $ 1 $ 7 $ (320) (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2019 $ (212) $ (116) $ 1 $ 7 $ (320) Other comprehensive income (loss) before reclassifications, net of tax of $(65) (136) (67) — 4 (199) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (45) — — — (45) – actuarial loss (a) 36 3 — — 39 – settlement loss (a) 22 — — — 22 Other — — — (6) (6) Tax effect (3) (1) — 1 (3) Other comprehensive loss (126) (65) — (1) (192) Balance as of December 31, 2020 $ (338) $ (181) $ 1 $ 6 $ (512) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 26.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Pension and Other Postretirement Plans	PENSION AND OTHER POSTRETIREMENT BENEFITS We have noncontributory defined benefit pension plans covering substantially all employees. Benefits under these plans have been based primarily on age, years of service and final average pensionable earnings. The years of service component of these formulae was frozen as of December 31, 2009. Certain of the pensionable earnings components were frozen as of December 31, 2012. Benefits for service beginning January 1, 2010 and beginning on January 1, 2016 are based on a cash balance formula with an annual percentage of eligible pay credited based upon age and years of service or at a flat rate of eligible pay, depending on covered employee group. Substantially all of our employees also accrue benefits under a defined contribution plan. (In millions) 2020 2019 2018 Cash balance weighted average interest crediting rates 3.00 % 3.18 % 3.00 % We also have other postretirement benefits covering most employees. Retiree health care benefits are provided through comprehensive hospital, surgical, major medical benefit, prescription drug and related health benefit provisions subject to various cost sharing features. Retiree life insurance benefits are provided to a closed group of retirees. Other postretirement benefits are not funded in advance. In connection with the Andeavor acquisition, we assumed a number of additional qualified and nonqualified noncontributory benefit pension plans, covering substantially all former Andeavor employees. Benefits under these plans are determined based on final average compensation and years of service through December 31, 2010 and a cash balance formula for service beginning January 1, 2011. These plans were frozen as of December 31, 2018. Further, as of December 31, 2019, the qualified plans were merged with our existing qualified plans in which the actuarial assumptions were materially the same between the plans. We also assumed a number of additional postretirement benefits covering eligible employees. These benefits were merged with our existing benefits beginning January 1, 2019. Obligations and Funded Status The accumulated benefit obligation for all defined benefit pension plans was $3,369 million and $3,013 million as of December 31, 2020 and 2019. The following summarizes our defined benefit pension plans that have accumulated benefit obligations in excess of plan assets. December 31, (In millions) 2020 2019 Projected benefit obligations $ 3,671 $ 3,220 Accumulated benefit obligations 3,369 3,013 Fair value of plan assets 2,621 2,531 The following summarizes the projected benefit obligations and funded status for our defined benefit pension and other postretirement plans: Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Change in benefit obligations: Benefit obligations at January 1 $ 3,220 $ 2,761 $ 1,020 $ 874 Service cost 302 234 35 31 Interest cost 98 107 32 37 Actuarial loss (a) 373 400 83 123 Benefits paid (322) (282) (39) (43) Plan amendments — — — (2) Benefit obligations at December 31 3,671 3,220 1,131 1,020 Change in plan assets: Fair value of plan assets at January 1 2,531 2,090 — — Actual return on plan assets 327 435 — — Employer contributions 85 288 39 43 Benefits paid from plan assets (322) (282) (39) (43) Fair value of plan assets at December 31 2,621 2,531 — — Funded status of plans at December 31 $ (1,050) $ (689) $ (1,131) $ (1,020) Amounts recognized in the consolidated balance sheets: Current liabilities $ (9) $ (47) $ (51) $ (46) Noncurrent liabilities (1,041) (642) (1,080) (974) Accrued benefit cost $ (1,050) $ (689) $ (1,131) $ (1,020) Pretax amounts recognized in accumulated other comprehensive loss: (b) Net actuarial loss $ 699 $ 577 $ 219 $ 139 Prior service cost (credit) (204) (250) 32 32 (a) The primary driver of the actuarial loss for the pension plans in 2020 and 2019 was the decrease in interest rates. The plans also saw moderate losses related to demographic experience in each year. (b) Amounts exclude those related to LOOP and Explorer, equity method investees with defined benefit pension and postretirement plans for which net losses of $16 million and less than $1 million were recorded in accumulated other comprehensive loss in 2020, reflecting our ownership share. Components of Net Periodic Benefit Cost and Other Comprehensive Loss The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive loss for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits (In millions) 2020 2019 2018 2020 2019 2018 Components of net periodic benefit cost: Service cost $ 283 $ 218 $ 147 $ 35 $ 31 $ 30 Interest cost 98 107 83 32 37 30 Expected return on plan assets (133) (127) (109) — — — Amortization – prior service credit (45) (45) (33) — — (3) – actuarial loss 36 22 31 3 — 1 – settlement loss 20 9 53 — — — Net periodic benefit cost (a) $ 259 $ 184 $ 172 $ 70 $ 68 $ 58 Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax): Actuarial (gain) loss $ 179 $ 92 $ 65 $ 83 $ 123 $ (72) Prior service cost (credit) — — (90) — (2) 34 Amortization of actuarial loss (56) (31) (84) (3) — (1) Amortization of prior service credit 45 45 33 — — 3 Total recognized in other comprehensive loss $ 168 $ 106 $ (76) $ 80 $ 121 $ (36) Total recognized in net periodic benefit cost and other comprehensive loss $ 427 $ 290 $ 96 $ 150 $ 189 $ 22 (a) Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years. For certain of our pension plans, lump sum payments to employees retiring in 2020, 2019 and 2018 exceeded the plan’s total service and interest costs expected for those years. Settlement losses are required to be recorded when lump sum payments exceed total service and interest costs. As a result, pension settlement expenses were recorded in 2020, 2019 and 2018. Plan Assumptions The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2020, 2019 and 2018. Pension Benefits Other Benefits 2020 2019 2018 2020 2019 2018 Weighted-average assumptions used to determine benefit obligation: Discount rate 2.44 % 3.08 % 4.21 % 2.55 % 3.00 % 4.26 % Rate of compensation increase 5.70 % 4.90 % 5.00 % 5.70 % 4.90 % 5.00 % Weighted-average assumptions used to determine net periodic benefit cost: Discount rate 3.00 % 4.07 % 3.89 % 3.23 % 4.30 % 3.72 % Expected long-term return on plan assets 5.75 % 6.00 % 6.15 % — % — % — % Rate of compensation increase 5.70 % 4.90 % 4.80 % 5.70 % 4.90 % 5.00 % Expected Long-term Return on Plan Assets The overall expected long-term return on plan assets assumption is determined based on an asset rate-of-return modeling tool developed by a third-party investment group. The tool utilizes underlying assumptions based on actual returns by asset category and inflation and takes into account our asset allocation to derive an expected long-term rate of return on those assets. Capital market assumptions reflect the long-term capital market outlook. The assumptions for equity and fixed income investments are developed using a building-block approach, reflecting observable inflation information and interest rate information available in the fixed income markets. Long-term assumptions for other asset categories are based on historical results, current market characteristics and the professional judgment of our internal and external investment teams. Assumed Health Care Cost Trend The following summarizes the assumed health care cost trend rates. December 31, 2020 2019 2018 Health care cost trend rate assumed for the following year: Medical: Pre-65 6.00 % 6.20 % 6.80 % Prescription drugs 7.00 % 8.10 % 9.50 % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate): Medical: Pre-65 4.50 % 4.50 % 4.50 % Prescription drugs 4.50 % 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate: Medical: Pre-65 2028 2027 2027 Prescription drugs 2028 2027 2027 Increases in the post-65 medical plan premium for the Marathon Petroleum Health Plan and the Marathon Petroleum Retiree Health Plan are the lower of the trend rate or four percent. Plan Investment Policies and Strategies The investment policies for our pension plan assets reflect the funded status of the plans and expectations regarding our future ability to make further contributions. Long-term investment goals are to: (1) manage the assets in accordance with the legal requirements of all applicable laws; (2) diversify plan investments across asset classes to achieve an optimal balance between risk and return and between income and growth of assets through capital appreciation; and (3) source benefit payments primarily through existing plan assets and anticipated future returns. The investment goals are implemented to manage the plans’ funded status volatility and minimize future cash contributions. The asset allocation strategy will change over time in response to changes primarily in funded status, which is dictated by current and anticipated market conditions, the independent actions of our investment committee, required cash flows to and from the plans and other factors deemed appropriate. Such changes in asset allocation are intended to allocate additional assets to the fixed income asset class should the funded status improve. The fixed income asset class shall be invested in such a manner that its interest rate sensitivity correlates highly with that of the plans’ liabilities. Other asset classes are intended to provide additional return with associated higher levels of risk. Investment performance and risk is measured and monitored on an ongoing basis through quarterly investment meetings and periodic asset and liability studies. At December 31, 2020, the primary plan’s targeted asset allocation was 50 percent equity, private equity, real estate, and timber securities and 50 percent fixed income securities. Fair Value Measurements Plan assets are measured at fair value. The following provides a description of the valuation techniques employed for each major plan asset category at December 31, 2020 and 2019. Cash and cash equivalents Cash and cash equivalents include a collective fund serving as the investment vehicle for the cash reserves and cash held by third-party investment managers. The collective fund is valued at net asset value (“NAV”) on a scheduled basis using a cost approach, and is considered a Level 2 asset. Cash and cash equivalents held by third-party investment managers are valued using a cost approach and are considered Level 2. Equity Equity investments includes common stock, mutual and pooled funds. Common stock investments are valued using a market approach, which are priced daily in active markets and are considered Level 1. Mutual and pooled equity funds are well diversified portfolios, representing a mix of strategies in domestic, international and emerging market strategies. Mutual funds are publicly registered, valued at NAV on a daily basis using a market approach and are considered Level 1 assets. Pooled funds are valued at NAV using a market approach and are considered Level 2. Fixed Income Fixed income investments include corporate bonds, U.S. dollar treasury bonds and municipal bonds. These securities are priced on observable inputs using a combination of market, income and cost approaches. These securities are considered Level 2 assets. Fixed income also includes a well diversified bond portfolio structured as a pooled fund. This fund is valued at NAV on a daily basis using a market approach and is considered Level 2. Other investments classified as Level 1 include mutual funds that are publicly registered, valued at NAV on a daily basis using a market approach. Private Equity Private equity investments include interests in limited partnerships which are valued using information provided by external managers for each individual investment held in the fund. These holdings are considered Level 3. Real Estate Real estate investments consist of interests in limited partnerships. These holdings are either appraised or valued using the investment manager’s assessment of assets held. These holdings are considered Level 3. Other Other investments include two limited liability companies (“LLCs”) with no public market. The LLCs were formed to acquire timberland in the northwest U.S. These holdings are either appraised or valued using the investment manager’s assessment of assets held. These holdings are considered Level 3. Other investments classified as Level 1 include publicly traded depository receipts. The following tables present the fair values of our defined benefit pension plans’ assets, by level within the fair value hierarchy, as of December 31, 2020 and 2019. December 31, 2020 (In millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 23 $ — $ 23 Equity: Common stocks 51 3 — 54 Mutual funds 353 — — 353 Pooled funds — 794 — 794 Fixed income: Corporate — 746 — 746 Government 327 128 — 455 Pooled funds — 131 — 131 Private equity — — 23 23 Real estate — — 20 20 Other — 3 19 22 Total investments, at fair value $ 731 $ 1,828 $ 62 $ 2,621 December 31, 2019 (In millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 22 $ — $ 22 Equity: Common stocks 125 135 — 260 Mutual funds 188 — — 188 Pooled funds — 442 — 442 Fixed income: Corporate 160 815 — 975 Government 113 217 — 330 Pooled funds — 229 — 229 Private equity — — 30 30 Real estate — — 24 24 Other 58 (46) 19 31 Total investments, at fair value $ 644 $ 1,814 $ 73 $ 2,531 The following is a reconciliation of the beginning and ending balances recorded for plan assets classified as Level 3 in the fair value hierarchy: 2020 (In millions) Private Equity Real Estate Other Beginning balance $ 30 $ 24 $ 19 Actual return on plan assets: Realized 6 1 — Unrealized (4) (3) — Purchases — 1 — Sales (9) (3) — Ending balance $ 23 $ 20 $ 19 2019 (In millions) Private Equity Real Estate Other Beginning balance $ 41 $ 29 $ 18 Actual return on plan assets: Realized 5 2 — Unrealized (3) (2) 1 Purchases 1 1 — Sales (14) (6) — Ending balance $ 30 $ 24 $ 19 Cash Flows Contributions to defined benefit plans Our funding policy with respect to the funded pension plans is to contribute amounts necessary to satisfy minimum pension funding requirements, including requirements of the Pension Protection Act of 2006, plus such additional, discretionary, amounts from time to time as determined appropriate by management. In 2020, we made contributions totaling $3 million to our funded pension plans. For 2021, we have $65 million of required funding, but we may also make voluntary contributions to our funded pension plans at our discretion. Cash contributions to be paid from our general assets for the unfunded pension and postretirement plans are estimated to be approximately $82 million and $52 million, respectively, in 2021. Estimated future benefit payments The following gross benefit payments, which reflect expected future service, as appropriate, are expected to be paid in the years indicated. (In millions) Pension Benefits Other Benefits 2021 $ 185 $ 52 2022 189 52 2023 194 52 2024 206 52 2025 212 53 2026 through 2030 1,172 280 Contributions to defined contribution plan We also contribute to a defined contribution plan for eligible employees. Contributions to this plan totaled $180 million, $181 million and $118 million in 2020, 2019 and 2018, respectively. Multiemployer Pension Plan We contribute to one multiemployer defined benefit pension plan under the terms of a collective-bargaining agreement that covers some of our union-represented employees. The risks of participating in this multiemployer plan are different from single-employer plans in the following aspects: • Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. • If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. • If we choose to stop participating in the multiemployer plan, we may be required to pay that plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. Our participation in this plan for 2020, 2019 and 2018 is outlined in the table below. The “EIN” column provides the Employee Identification Number for the plan. The most recent Pension Protection Act zone status available in 2020 and 2019 is for the plan’s year ended December 31, 2019 and December 31, 2018, respectively. The zone status is based on information that we received from the plan and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than 65 percent funded. The “FIP/RP Status Pending/Implemented” column indicates a financial improvement plan or a rehabilitation plan has been implemented. The last column lists the expiration date of the collective-bargaining agreement to which the plan is subject. There have been no significant changes that affect the comparability of 2020, 2019 and 2018 contributions. Our portion of the contributions does not make up more than five percent of total contributions to the plan. Pension FIP/RP Status MPC Contributions In millions ) Surcharge Expiration Date of Pension Fund EIN 2020 2019 2020 2019 2018 Central States, Southeast and Southwest Areas Pension Plan (a) 366044243 Red Red Implemented $ 5 $ 4 $ 4 No January 31, 2024 (a) This agreement has a minimum contribution requirement of $338 per week per employee for 2021. A total of 275 employees participated in the plan as of December 31, 2020. Multiemployer Health and Welfare Plan We contribute to one multiemployer health and welfare plan that covers both active employees and retirees. Through the health and welfare plan employees receive medical, dental, vision, prescription and disability coverage. Our contributions to this plan totaled $7 million, $6 million and $6 million for 2020, 2019 and 2018, respectively.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION Description of the Plans Effective April 26, 2012, our employees and non-employee directors became eligible to receive equity awards under the Amended and Restated Marathon Petroleum Corporation 2012 Incentive Compensation Plan (“MPC 2012 Plan”). The MPC 2012 Plan authorizes the Compensation and Organization Development Committee of our board of directors (“Committee”) to grant non-qualified or incentive stock options, stock appreciation rights, stock awards (including restricted stock and restricted stock unit awards), cash awards and performance awards to our employees and non-employee directors. Under the MPC 2012 Plan, no more than 50 million shares of our common stock may be delivered and no more than 20 million shares of our common stock may be the subject of awards that are not stock options or stock appreciation rights. In the sole discretion of the Committee, 20 million shares of our common stock may be granted as incentive stock options. Shares issued as a result of awards granted under these plans are funded through the issuance of new MPC common shares. Prior to April 26, 2012, our employees and non-employee directors were eligible to receive equity awards under the Marathon Petroleum Corporation 2011 Second Amended and Restated Incentive Compensation Plan (“MPC 2011 Plan”). In connection with the Andeavor acquisition in October of 2018, we converted the outstanding option and equity incentive awards (other than awards held by non-employee directors of Andeavor, which awards were paid out in connection with the acquisition) under the Andeavor plans to awards that provide for rights to acquire (in the case of options) or be settled in or otherwise determined in reference to shares of MPC common stock in place of shares of Andeavor common stock (in the case of equity incentive awards). As part of that conversion, we used an exchange ratio for the respective share prices of Andeavor common stock and MPC common stock to ensure that the award holders’ economic opportunity remained constant, and for converted awards, which included a performance component, performance was determined at the time of the conversion and the awards became subject to a time-based vesting only design. The converted awards otherwise continue to be subject to the terms and conditions of their award agreements and the applicable Andeavor plan under which such awards were granted. Stock-Based Awards under the Plans We expense all share-based payments to employees and non-employee directors based on the grant date fair value of the awards over the requisite service period, adjusted for estimated forfeitures. Stock Options We grant stock options to certain officer and non-officer employees. All of the stock options granted in 2020 were granted under the MPC 2012 Plan. Stock options awarded under the MPC 2011 Plan and the MPC 2012 Plan represent the right to purchase shares of our common stock at its fair market value, which is the closing price of MPC’s common stock on the date of grant. Stock options have a maximum term of ten years from the date they are granted, and vest over a requisite service period of three years. We use the Black Scholes option-pricing model to estimate the fair value of stock options granted, which requires the input of subjective assumptions. Restricted Stock and Restricted Stock Units We grant restricted stock and restricted stock units to employees and non-employee directors. In general, restricted stock and restricted stock units granted to employees vest over a requisite service period of three years. Restricted stock and restricted stock unit awards granted to officers are subject to an additional one year holding period after the three-year vesting period. Restricted stock recipients have the right to vote such stock; however, dividends are accrued and when vested are payable at the dates specified in the awards. The non-vested shares are not transferable and are held by our transfer agent. The fair values of restricted stock are equal to the market price of our common stock on the grant date. Restricted stock units granted to non-employee directors are considered to vest immediately at the time of the grant for accounting purposes, as they are non-forfeitable, but are not issued until the director’s departure from the board of directors. Restricted stock unit recipients do not have the right to vote any shares of stock and accrue dividend equivalents which when vested are payable at the dates specified in the awards. Performance Units We grant performance unit awards to certain officer employees. Performance units are dollar denominated. The target value of all performance units is $1.00, with actual payout up to $2.00 per unit (up to 200 percent of target). Performance units issued under the MPC 2012 Plan have a 36-month requisite service period. The payout value of these awards will be determined by the relative ranking of the total shareholder return (“TSR” ) of MPC common stock compared to the TSR of a select group of peer companies, as well as the Standard & Poor’s 500 Energy Index fund over an average of four measurement periods. These awards will be settled 25 percent in MPC common stock and 75 percent in cash. The number of shares actually distributed will be determined by dividing 25 percent of the final payout by the closing price of MPC common stock on the day the Committee certifies the final TSR rankings, or the next trading day if the certification is made outside of normal trading hours. The performance units paying out in cash are accounted for as liability awards and recorded at fair value with a mark-to-market adjustment made each quarter. The performance units that settle in shares are accounted for as equity awards and do not receive dividend equivalents. Total Stock-Based Compensation Expense The following table reflects activity related to our stock-based compensation arrangements, including the converted awards related to the acquisition of Andeavor: (In millions) 2020 2019 2018 Stock-based compensation expense $ 100 $ 153 $ 127 Tax benefit recognized on stock-based compensation expense 25 35 31 Cash received by MPC upon exercise of stock option awards 11 10 24 Tax (expense)/benefit received for tax deductions for stock awards exercised 16 (3) 14 Stock Option Awards The Black Scholes option-pricing model values used to value stock option awards granted were determined based on the following weighted average assumptions: 2020 2019 2018 Weighted average exercise price per share $ 28.78 $ 61.92 $ 67.71 Expected life in years 5.9 6.0 6.2 Expected volatility 39 % 32 % 34 % Expected dividend yield 4.7 % 3.4 % 3.0 % Risk-free interest rate 0.6 % 2.4 % 2.7 % Weighted average grant date fair value of stock option awards granted $ 7.40 $ 13.65 $ 17.21 The expected life of stock options granted is based on historical data and represents the period of time that options granted are expected to be held prior to exercise. The 2020 assumption for expected volatility of our stock price reflects a weighting of 50 percent of our common stock implied volatility and 50 percent of our common stock historical volatility. The risk-free interest rate for periods within the expected life of the option is based on the U.S. Treasury yield curve in effect at the time of the grant. The following is a summary of our common stock option activity in 2020: Number of Weighted Average Exercise Price Weighted Average Remaining Contractual Terms (in years) Aggregate Intrinsic Value (in millions) Outstanding at December 31, 2019 10,018,367 $ 42.55 Granted 2,770,139 28.78 Exercised (1,016,593) 14.15 Forfeited or expired (472,132) 37.77 Outstanding at December 31, 2020 11,299,781 41.95 Vested and expected to vest at December 31, 2020 11,243,905 29.28 5.2 $ 76 Exercisable at December 31, 2020 7,641,774 42.61 3.6 42 The intrinsic value of options exercised by MPC employees during 2020, 2019 and 2018 was $25 million, $23 million and $44 million, respectively. As of December 31, 2020, unrecognized compensation cost related to stock option awards was $15 million, which is expected to be recognized over a weighted average period of 1.8 years. Restricted Stock and Restricted Stock Unit Awards The following is a summary of restricted stock award activity of our common stock in 2020: Restricted Stock Restricted Stock Units Number of Weighted Number of Weighted Unvested at December 31, 2019 1,349,798 $ 62.20 1,481,746 $ 82.39 Granted 2,463 56.49 3,076,347 22.82 Vested (646,358) 61.58 (823,111) 77.01 Forfeited (125,924) 62.11 (410,658) 27.76 Unvested at December 31, 2020 579,979 62.89 3,324,324 35.34 The following is a summary of the values related to restricted stock and restricted stock unit awards held by MPC employees and non-employee directors: Restricted Stock Restricted Stock Units Intrinsic Value of Awards Vested During the Period (in millions) Weighted Average Grant Date Fair Value of Awards Granted During the Period Intrinsic Value of Awards Vested During the Period (in millions) Weighted Average Grant Date Fair Value of Awards Granted During the Period 2020 $ 18 $ 56.49 $ 59 $ 22.82 2019 32 61.14 120 58.30 2018 49 71.19 39 72.43 As of December 31, 2020, unrecognized compensation cost related to restricted stock awards was $19 million, which is expected to be recognized over a weighted average period of 1.0 year. Unrecognized compensation cost related to restricted stock unit awards was $43 million, which is expected to be recognized over a weighted average period of 1.76 years. Performance Unit Awards The following table presents a summary of the 2020 activity for performance unit awards to be settled in shares: Number of Units Weighted Average Grant Date Fair Value Unvested at December 31, 2019 11,199,500 $ 0.80 Granted 3,360,000 0.89 Vested (3,490,750) 0.89 Forfeited (58,713) 0.75 Unvested at December 31, 2020 11,010,037 0.80 The number of shares that would be issued upon target vesting, using the closing price of our common stock on December 31, 2020 would be 320,661 shares. As of December 31, 2020, unrecognized compensation cost related to equity-classified performance unit awards was $2 million, which is expected to be recognized over a weighted average period of 1.94 years. Performance units to be settled in MPC shares have a grant date fair value calculated using a Monte Carlo valuation model, which requires the input of subjective assumptions. The following table provides a summary of these assumptions: 2020 2019 2018 Risk-free interest rate 0.9 % 2.5 % 2.3 % Look-back period (in years) 2.8 2.8 2.8 Expected volatility 30.4 % 29.7 % 34.0 % Grant date fair value of performance units granted $ 0.89 $ 0.72 $ 0.83 The risk-free interest rate for the remaining performance period as of the grant date is based on the U.S. Treasury yield curve in effect at the time of the grant. The look-back period reflects the remaining performance period at the grant date. The assumption for the expected volatility of our stock price reflects the average MPC common stock historical volatility. MPLX Awards Compensation expense for awards of MPLX units are not material to our consolidated financial statements for 2020.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases of Lessee Disclosure	Lessee We lease a wide variety of facilities and equipment including land and building space, office and field equipment, storage facilities and transportation equipment. Our remaining lease terms range from less than one year to 58 years. Most long-term leases include renewal options ranging from less than one year to 49 years and, in certain leases, also include purchase options. The lease term included in the measurement of right of use assets and lease liabilities includes options to extend or terminate our leases that we are reasonably certain to exercise. Under ASC 842, the components of lease cost are shown below. Lease costs for operating leases are recognized on a straight line basis and are reflected in the income statement based on the leased asset’s use. Lease costs for finance leases are reflected in depreciation and amortization and in net interest and other financial costs. (In millions) 2020 2019 Finance lease cost: Amortization of right of use assets $ 72 $ 59 Interest on lease liabilities 35 37 Operating lease cost 658 660 Variable lease cost 60 68 Short-term lease cost 631 735 Total lease cost $ 1,456 $ 1,559 Supplemental balance sheet data related to leases were as follows: December 31, (In millions) 2020 2019 Operating leases Assets Right of use assets $ 1,521 $ 1,806 Liabilities Operating lease liabilities $ 497 $ 514 Long-term operating lease liabilities 1,014 1,300 Total operating lease liabilities $ 1,511 $ 1,814 Weighted average remaining lease term (in years) 4.8 5.1 Weighted average discount rate 3.68 % 3.91 % Finance leases Assets Property, plant and equipment, gross $ 819 $ 740 Less accumulated depreciation 272 215 Property, plant and equipment, net $ 547 $ 525 Liabilities Debt due within one year $ 69 $ 56 Long-term debt 576 537 Total finance lease liabilities $ 645 $ 593 Weighted average remaining lease term (in years) 10.7 11.6 Weighted average discount rate 5.33 % 6.63 % As of December 31, 2020, 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) Operating Finance 2021 $ 544 $ 91 2022 373 99 2023 243 101 2024 170 84 2025 111 76 2026 and thereafter 224 402 Gross lease payments 1,665 853 Less: imputed interest 154 208 Total lease liabilities $ 1,511 $ 645
Leases of Lessor Disclosure	Lessor MPLX has certain natural gas gathering, transportation and processing agreements in which it is considered to be the lessor under several operating lease arrangements in accordance with GAAP. MPLX’s primary natural gas lease operations relate to a natural gas gathering agreement in the Marcellus Shale for which it earns a fixed-fee for providing gathering services to a single producer using a dedicated gathering system. As the gathering system is expanded, the fixed-fee charged to the producer is adjusted to include the additional gathering assets in the lease. The primary term of the natural gas gathering arrangement expires in 2038 and will continue thereafter on a year-to-year basis until terminated by either party. Other significant natural gas implicit leases relate to a natural gas processing agreement in the Marcellus Shale and a natural gas processing agreement in the Southern Appalachia region for which MPLX earns minimum monthly fees for providing processing services to a single producer using a dedicated processing plant. The primary term of these natural gas processing agreements expires during 2027 and 2023, respectively, and will continue thereafter on a year-to-year basis until terminated by either party. 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. Lessor agreements are currently deemed operating, as MPLX elected the practical expedient to carry forward historical classification conclusions. If and when a modification of an existing agreement occurs and the agreement is required to assessed under ASC 842, MPLX assesses the amended agreement and makes a determination as to whether a reclassification of the lease is required. Our revenue from implicit lease arrangements, excluding executory costs, totaled approximately $273 million and $254 million in 2020 and 2019, respectively. Under ASC 840, our revenue from implicit lease arrangements, excluding executory costs, totaled approximately $221 million in 2018. The following is a schedule of minimum future rentals on the non‑cancellable operating leases as of December 31, 2020: (In millions) 2021 $ 186 2022 181 2023 178 2024 174 2025 142 2026 and thereafter 999 Total minimum future rentals $ 1,860 The following schedule summarizes our investment in assets held for operating lease by major classes as of December 31, 2020 and 2019: December 31, (In millions) 2020 2019 Gathering and transportation $ 990 $ 980 Processing and fractionation 867 855 Terminals 128 83 Land, building and other 15 17 Property, plant and equipment 2,000 1,935 Less accumulated depreciation 430 327 Total property, plant and equipment, net $ 1,570 $ 1,608

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which we have not recorded a liability, we are 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 We are subject to federal, state, local and foreign 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 and certain other locations including presently or formerly owned or operated retail marketing sites. Penalties may be imposed for noncompliance. At December 31, 2020 and 2019, accrued liabilities for remediation totaled $397 million and $396 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, that may be imposed. Receivables for recoverable costs from certain states, under programs to assist companies in clean-up efforts related to underground storage tanks at presently or formerly owned or operated retail marketing sites, were $7 million and $9 million at December 31, 2020 and 2019, respectively. Governmental and other entities in various states have filed lawsuits against energy companies, including MPC. The lawsuits allege damages as a result of climate change and the plaintiffs are seeking unspecified damages and abatement under various tort theories. We are currently subject to such proceedings in federal or state courts in California, Delaware, Maryland, Hawaii, Rhode Island and South Carolina. Similar lawsuits may be filed in other jurisdictions. At this early stage, the ultimate outcome of these matters remain uncertain, and neither the likelihood of an unfavorable outcome nor the ultimate liability, if any, can be determined. We are involved in a number of environmental enforcement matters arising in the ordinary course of business. While the outcome and impact on us cannot be predicted with certainty, management believes the resolution of these environmental matters will not, individually or collectively, have a material adverse effect on our consolidated results of operations, financial position or cash flows. Asset Retirement Obligations Our short-term asset retirement obligations were $14 million and $20 million at December 31, 2020 and 2019, respectively, which are included in other current liabilities in our consolidated balance sheets. Our long-term asset retirement obligations were $183 million and $184 million at December 31, 2020 and 2019, respectively, which are included in deferred credits and other liabilities in our consolidated balance sheets. Other Legal Proceedings In early July 2020, MPLX received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline (“THPP”), which crosses the Fort Berthold Reservation in North Dakota. The notification covered the rights of way for 23 tracts of land and demanded the immediate cessation of pipeline operations. The notification also assessed trespass damages of approximately $187 million. MPLX appealed this determination, which triggered an automatic stay of the requested pipeline shutdown and payment. On October 29, the Assistant Secretary - Indian Affairs issued an order vacating the BIA’s trespass order and requiring the Regional Director for the BIA Great Plains Region to issue a new decision on or before December 15 covering all 34 tracts at issue. On December 15, the Regional Director of the BIA issued a new trespass notice to THPP consistent with the Assistant Secretary of Indian Affairs order vacating the prior trespass order. The new order found that THPP was in trespass and assessed trespass damages of approximately $4 million (including interest), which has been paid. The order also required THPP to immediately cease and desist use of the portion of the pipeline that crosses the property at issue. THPP has complied with the Regional Director’s December 15, 2020 notice. On February 12, 2021, landowners filed suit in the U.S. District Court for the District of North Dakota, requesting, among other things, that decisions by the Assistant Secretary - Indian Affairs and the Interior Board of Indian Appeals be vacated as to the award of damages to plaintiffs. MPLX continues to work towards a settlement of this matter with holders of the property rights at issue. Management does not believe the ultimate resolution of this matter will have a material adverse effect on our consolidated financial position, results of operations, or cash flows. We are 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 us cannot be predicted with certainty, we believe that the resolution of these other lawsuits and proceedings will not have a material adverse effect on our consolidated financial position, results of operations or cash flows. Guarantees We have provided certain guarantees, direct and indirect, of the indebtedness of other companies. Under the terms of most of these guarantee arrangements, we would be required to perform should the guaranteed party fail to fulfill its obligations under the specified arrangements. In addition to these financial guarantees, we also have various performance guarantees related to specific agreements. Guarantees related to indebtedness of equity method investees LOOP and LOCAP MPC and MPLX hold interests in an offshore oil port, LOOP, and MPLX holds an interest in a crude oil pipeline system, LOCAP. Both LOOP and LOCAP have secured various project financings with throughput and deficiency agreements. Under the agreements, MPC, as a shipper, is required to advance funds if the investees are unable to service their debt. Any such advances are considered prepayments of future transportation charges. The duration of the agreements varies but tend to follow the terms of the underlying debt, which extend through 2037. Our maximum potential undiscounted payments under these agreements for the debt principal totaled $171 million as of December 31, 2020. Dakota Access Pipeline In connection with MPLX’s approximate 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL, MPLX entered into a Contingent Equity Contribution Agreement. MPLX, 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. In March 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to conduct a full environmental impact statement (“EIS”), and further requested briefing on whether an easement necessary for the operation of the Bakken Pipeline system should be vacated while the EIS is being prepared. On July 6, 2020, the D.D.C. ordered vacatur of the easement to cross Lake Oahe during the pendency of an EIS and further ordered a shut down of the pipeline by August 5, 2020. The D.D.C. denied a motion to stay that order. Dakota Access and the Army Corps appealed the D.D.C.’s orders to the U.S. Court of Appeals for the District of Columbia Circuit (the “Court of Appeals”). On July 14, 2020, the Court of Appeals issued an administrative stay while the court considered Dakota Access and the Army Corps’ emergency motion for stay pending appeal. On August 5, 2020, the Court of Appeals stayed the D.D.C.’s injunction that required the pipeline be shutdown and emptied of oil by August 5, 2020. The Court of Appeals denied a stay of the D.D.C.’s March order, which required the EIS, and further denied a stay of the D.D.C.’s July order, which vacated the easement. On January 26, 2021, the Court of Appeals upheld the D.D.C.’s order vacating the easement while the Army Corps prepares the EIS. The Court of Appeals reversed the D.D.C.’s order to the extent it directed that the pipeline be shutdown and emptied of oil. In the D.D.C., briefing has been completed for a renewed request for an injunction. The pipeline remains operational. If the pipeline is temporarily shut down pending completion of the EIS, 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. It is expected that MPLX would contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of December 31, 2020, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $230 million. Crowley Ocean Partners and Crowley Blue Water Partners In connection with our 50 percent ownership in Crowley Ocean Partners, we have agreed to conditionally guarantee our portion of the obligations of the joint venture and its subsidiaries under a senior secured term loan agreement. The term loan agreement provides for loans of up to $325 million to finance the acquisition of four product tankers. MPC’s liability under the guarantee for each vessel is conditioned upon the occurrence of certain events, including if we cease to maintain an investment grade credit rating or the charter for the relevant product tanker ceases to be in effect and is not replaced by a charter with an investment grade company on certain defined commercial terms. As of December 31, 2020, our maximum potential undiscounted payments under this agreement for debt principal totaled $119 million. In connection with our 50 percent indirect interest in Crowley Blue Water Partners, we have agreed to provide a conditional guarantee of up to 50 percent of its outstanding debt balance in the event there is no charter agreement in place with an investment grade customer for the entity’s three vessels as well as other financial support in certain circumstances. As of December 31, 2020, our maximum potential undiscounted payments under this arrangement was $115 million. Marathon Oil indemnifications The separation and distribution agreement and other agreements with Marathon Oil to effect our spinoff provide for cross-indemnities between Marathon Oil and us. In general, Marathon Oil is required to indemnify us for any liabilities relating to Marathon Oil’s historical oil and gas exploration and production operations, oil sands mining operations and integrated gas operations, and we are required to indemnify Marathon Oil for any liabilities relating to Marathon Oil’s historical refining, marketing and transportation operations. The terms of these indemnifications are indefinite and the amounts are not capped. Other guarantees We have entered into other guarantees with maximum potential undiscounted payments totaling $99 million as of December 31, 2020, which primarily consist of a commitment to contribute cash to an equity method investee for certain catastrophic events, in lieu of procuring insurance coverage, a commitment to fund a share of the bonds issued by a government entity for construction of public utilities in the event that other industrial users of the facility default on their utility payments and leases of assets containing general lease indemnities and guaranteed residual values. General guarantees associated with dispositions Over the years, we have sold various assets in the normal course of our 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 us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are 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. Contractual Commitments and Contingencies At December 31, 2020 and 2019, our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $1.7 billion and $1.6 billion, respectively. Certain natural gas processing and gathering arrangements require us to construct 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 producer customers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Data [Abstract]
Selected Quarterly Financial Data	SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) As a result of the agreement to sell Speedway, Speedway’s results are reported separately as discontinued operations in our consolidated statements of income for all periods presented. Prior to presentation of Speedway as discontinued operations, Speedway and our retained direct dealer business were the two reporting units within our Retail segment. Beginning with the third quarter of 2020, the direct dealer business is managed as part of the Refining & Marketing segment. The results of the Refining & Marketing segment have been retrospectively adjusted to include the results of the direct dealer business in all periods presented. In accordance with ASC 205, Discontinued Operations, intersegment sales from our Refining & Marketing segment to Speedway are no longer eliminated as intercompany transactions and are now presented within sales and other operating revenue, since we will continue to supply fuel to Speedway subsequent to the sale to 7-Eleven. All periods presented have been retrospectively adjusted to reflect this change. 2020 Quarter Ended (In millions, except per share data) March 31 June 30 September 30 December 31 Sales and other operating revenues $ 22,204 $ 12,195 $ 17,408 $ 17,972 Income (loss) from continuing operations (12,155) 575 (1,057) 390 Income (loss) from continuing operations, net of tax (10,536) 84 (980) 250 Net income (loss) (10,218) 276 (609) 574 Net income (loss) attributable to MPC (9,234) 9 (886) 285 Income (loss) from continuing operations per share (a) : Basic $ (14.74) $ (0.28) $ (1.93) $ (0.06) Diluted (14.74) (0.28) (1.93) (0.06) 2019 Quarter Ended (In millions, except per share data) March 31 June 30 September 30 December 31 Sales and other operating revenues $ 25,349 $ 30,239 $ 27,552 $ 28,008 Income from continuing operations 526 1,698 1,680 558 Income from continuing operations, net of tax 150 1,109 1,113 77 Net income 259 1,367 1,367 262 Net income (loss) attributable to MPC (7) 1,106 1,095 443 Income (loss) from continuing operations per share (a) : Basic $ (0.17) $ 1.28 $ 1.28 $ 0.40 Diluted (0.17) 1.27 1.27 0.40 (a) The sum of the per-share amounts for the four quarters may not always equal the annual per-share amounts due to differences in the average number of shares outstanding during the respective periods.

Summary of Principal Accounti_2

Summary of Principal Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Principles applied in consolidation	Principles Applied in Consolidation These consolidated financial statements include the accounts of our majority-owned, controlled subsidiaries and MPLX. As of December 31, 2020, we owned the general partner and 62 percent of the outstanding MPLX common units. Due to our ownership of the general partner interest, we have determined that we control MPLX and therefore we consolidate MPLX and record a noncontrolling interest for the interest owned by the public. Changes in ownership interest in consolidated subsidiaries that do not result in a change in control are recorded as equity transactions. Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority shareholders have substantive participating rights. Income from equity method investments represents our proportionate share of net income generated by the equity method investees. 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 any excess related to goodwill. Equity method investments are evaluated for impairment whenever changes in the facts and circumstances indicate an other than temporary loss in value has occurred. When the loss is deemed to be other than temporary, the carrying value of the equity method investment is written down to fair value.
Use of estimates	Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles 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.
Revenue recognition	Revenue Recognition We recognize revenue based on consideration specified in contracts or agreements with customers when we satisfy our performance obligations by transferring control over products or services to a customer. Concurrent with our adoption of ASU 2014-09, Revenue from Contracts with Customers (“ASC 606”), as of January 1, 2018, we made an accounting policy election that all taxes assessed by a governmental authority that are both imposed on and concurrent with a revenue-producing transaction and collected from our customers will be recognized on a net basis within sales and other operating revenues. Our revenue recognition patterns are described below by reportable segment: • Refining & Marketing - The vast majority of our Refining & Marketing contracts contain pricing that is based on the market price for the product at the time of delivery. Our obligations to deliver product volumes are typically satisfied and revenue is recognized when control of the product transfers to our customers. Concurrent with the transfer of control, we typically receive the right to payment for the delivered product, the customer accepts the product and the customer has significant risks and rewards of ownership of the product. Payment terms require customers to pay shortly after delivery and do not contain significant financing components. • Midstream - Midstream revenue transactions typically are defined by contracts under which we sell a product or provide a service. Revenues from sales of product are recognized when control of the product transfers to the customer. Revenues from sales of services are recognized over time when the performance obligation is satisfied as services are provided in a series. We have elected to use the output measure of progress to recognize revenue based on the units delivered, processed or transported. The transaction prices in our Midstream contracts often have both 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 at each period end. Refer to Note 23 for disclosure of our revenue disaggregated by segment and product line and to Note 13 for a description of our reportable segment operations.
Crude oil and refined product exchanges and matching buy/sell transactions	Crude Oil and Refined Product Exchanges and Matching Buy/Sell Transactions We enter into exchange contracts and matching buy/sell arrangements whereby we agree to deliver a particular quantity and quality of crude oil or refined products at a specified location and date to a particular counterparty and to receive from the same counterparty the same commodity at a specified location on the same or another specified date. The exchange receipts and deliveries are nonmonetary transactions, with the exception of associated grade or location differentials that are settled in cash. The matching buy/sell purchase and sale transactions are settled in cash. No revenues are recorded for exchange and matching buy/sell transactions as they are accounted for as exchanges of inventory. The exchange transactions are recognized at the carrying amount of the inventory transferred.
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.
Restricted cash	Restricted Cash Restricted cash consists of cash and investments that must be maintained as collateral for letters of credit issued to certain third-party producer customers. The balances will be outstanding until certain capital projects are completed and the third party releases the restriction.
Accounts receivable and allowance for doubtful accounts	Accounts Receivable and Allowance for Doubtful Accounts Our receivables primarily consist of customer accounts receivable. Customer receivables are recorded at the invoiced amounts and generally do not bear interest. Allowances for doubtful accounts are generally recorded when it becomes probable the receivable will not be collected and are booked to bad debt expense. The allowance for doubtful accounts is the best estimate of the amount of probable credit losses in customer accounts receivable. We review the allowance quarterly and past-due balances over 180 days are reviewed individually for collectability. We mitigate credit risk with master netting agreements with companies engaged in the crude oil or refinery feedstock trading and supply business or the petroleum refining industry. A master netting agreement generally provides for a once per month net cash settlement of the accounts receivable from and the accounts payable to a particular counterparty.
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 assets. 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 equipment leases. The lease component of the payment for the marine and equipment asset classes is determined using a relative standalone selling price. See Note 28 for additional disclosures about our lease contracts.
Inventories	Inventories Inventories are carried at the lower of cost or market value. Cost of inventories is determined primarily under the LIFO method. Costs for crude oil and refined product inventories are aggregated on a consolidated basis for purposes of assessing if the LIFO cost basis of these inventories may have to be written down to market value.
Derivative instruments	Derivative Instruments We use derivatives to economically hedge a portion of our exposure to commodity price risk and, historically, to interest rate risk. Our use of selective derivative instruments that assume market risk is limited. All derivative instruments (including derivative instruments embedded in other contracts) are recorded at fair value. Certain commodity derivatives are reflected on the consolidated balance sheets on a net basis by counterparty as they are governed by master netting agreements. Cash flows related to derivatives used to hedge commodity price risk and interest rate risk are classified in operating activities with the underlying transactions. Derivatives not designated as accounting hedges Derivatives that are not designated as accounting hedges may include commodity derivatives used to hedge price risk on (1) inventories, (2) fixed price sales of refined products, (3) the acquisition of foreign-sourced crude oil, (4) the acquisition of ethanol for blending with refined products, (5) the sale of NGLs, (6) the purchase of natural gas and (7) the purchase of soybean oil. Changes in the fair value of derivatives not designated as accounting hedges are recognized immediately in net income. Concentrations of credit risk All of our financial instruments, including derivatives, involve elements of credit and market risk. The most significant portion of our credit risk relates to nonperformance by counterparties. The counterparties to our financial instruments consist primarily of major financial institutions and companies within the energy industry. To manage counterparty risk associated with financial instruments, we select and monitor counterparties based on an assessment of their financial strength and on credit ratings, if available. Additionally, we limit the level of exposure with any single counterparty.
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, which range from one year to 61 years. Such assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset group may not be recoverable. If the sum of the expected undiscounted future cash flows from the use of the asset group and its eventual disposition is less than the carrying amount of the asset group, an impairment assessment is performed and the excess of the book value over the fair value of the asset group 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 in net income. Gains on the disposal of property, plant and equipment are recognized when earned, 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 expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset.
Goodwill and intangible assets	Goodwill and Intangible Assets 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/or 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. 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. Intangibles not subject to amortization are tested for impairment annually and when circumstances indicate that the fair value is less than the carrying amount of the intangible. If the fair value is less than the carrying value, an impairment is recorded for the difference.
Major maintenance activities	Major Maintenance Activities Costs for planned turnaround and other major maintenance activities are expensed in the period incurred. These types of costs include contractor repair services, materials and supplies, equipment rentals and our labor costs.
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 The fair value of asset retirement obligations is recognized in the period in which the obligations are incurred if a reasonable estimate of fair value can be made. The majority of our recognized asset retirement liability relates to conditional asset retirement obligations for removal and disposal of fire-retardant material from certain refining facilities. The remaining recognized asset retirement liability relates to other refining assets, certain pipelines and processing facilities and other related pipeline assets. The fair values recorded for such obligations are based on the most probable current cost projections. Asset retirement obligations have not been recognized for some 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. The asset retirement obligations principally include the hazardous material disposal and removal or dismantlement requirements associated with the closure of certain refining, terminal, pipeline and processing assets. Our practice is to keep our assets in good operating condition through routine repair and maintenance of component parts in the ordinary course of business and by continuing to make improvements based on technological advances. As a result, we believe that generally these assets have no expected settlement date for purposes of estimating asset retirement obligations since the dates or ranges of dates upon which we would retire these assets cannot be reasonably estimated at this time.
Income taxes	Income Taxes Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their tax bases. Deferred tax assets are recorded when it is more likely than not that they will be realized. The realization of deferred tax assets is assessed periodically based on several factors, primarily our expectation to generate sufficient future taxable income.
Stock-based compensation arrangements	Stock-Based Compensation Arrangements The fair value of stock options granted to our employees is estimated on the date of grant using the Black-Scholes option pricing model. The model employs various assumptions based on management’s estimates at the time of grant, which impact the calculation of fair value and ultimately, the amount of expense that is recognized over the vesting period of the stock option award. Of the required assumptions, the expected life of the stock option award and the expected volatility of our stock price have the most significant impact on the fair value calculation. The average expected life is based on our historical employee exercise behavior. The assumption for expected volatility of our stock price reflects a weighting of 50 percent of our common stock implied volatility and 50 percent of our common stock historical volatility. The fair value of restricted stock awards granted to our employees is determined based on the fair market value of our common stock on the date of grant. The fair value of performance unit awards granted to our employees is estimated on the date of grant using a Monte Carlo valuation model.
Business combinations	Business Combinations
Environmental credits and obligations	Environmental Credits and Obligations In order to comply with certain regulations, specifically the RFS2 requirements implemented by the EPA and the cap-and-trade emission reduction program and low carbon fuel standard implemented by the state of California, we are required to reduce our emissions, blend certain levels of biofuels or obtain allowances or credits to offset the obligations created by our operations. In regard to each program, we record an asset, included in other current or other noncurrent assets on the balance sheet, for allowances or credits owned in excess of our anticipated current period compliance requirements. The asset value is based on the product of the excess allowances or credits as of the balance sheet date, if any, and the weighted average cost of those allowances or credits. We record a liability, included in other current or other noncurrent liabilities on the balance sheet, when we are deficient allowances or credits based on the product of the deficient amount as of the balance sheet date, if any, and the market price of the allowances or credits at the balance sheet date. The cost of allowances or credits used for compliance is reflected in cost of revenues on the income statement. Any gains or losses on the sale or expiration of allowances or credits are classified as other income on the income statement. Proceeds from the sale of allowances or credits are reported in investing activities - all other, net on the cash flow statement.

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost	(In millions) Employee separation costs Exit and disposal costs Total Restructuring reserve balance at September 30, 2020 (a) $ 158 $ 133 $ 291 Adjustments 14 5 19 Cash payments (134) (35) (169) Restructuring reserve balance at December 31, 2020 $ 38 $ 103 $ 141 (a) The restructuring reserve was zero until the third quarter of 2020.

Discontinued Operations and A_2

Discontinued Operations and Assets Held for Sale (Tables)	12 Months Ended
	Dec. 31, 2020
Speedway
Disposal Groups, Including Discontinued Operations	The following tables present Speedway results as reported in income from discontinued operations, net of tax, within our consolidated statements of income and the carrying value of assets and liabilities as presented within assets and liabilities held for sale on our consolidated balance sheets. (In millions) 2020 2019 2018 Total revenues and other income $ 19,920 $ 26,793 $ 22,051 Costs and expenses: Cost of revenues (excludes items below) 17,573 24,860 20,557 Depreciation and amortization 244 413 320 Selling, general and administrative expenses 323 216 142 Other taxes 193 190 151 Total costs and expenses 18,333 25,679 21,170 Income from operations 1,587 1,114 881 Net interest and other financial costs 20 18 10 Income before income taxes 1,567 1,096 871 Provision for income taxes 362 290 198 Income from discontinued operations, net of tax $ 1,205 $ 806 $ 673 December 31, (In millions) 2020 2019 Assets Cash and cash equivalents $ 140 $ 134 Receivables 217 246 Inventories 438 439 Other current assets 34 28 Equity method investments 311 330 Property, plant and equipment, net 4,784 4,745 Goodwill 4,390 4,390 Right of use assets 719 653 Other noncurrent assets 168 170 Total assets classified as held for sale $ 11,201 $ 11,135 Liabilities Accounts payable $ 300 $ 401 Payroll and benefits payable 168 139 Accrued taxes 178 171 Debt due within one year 8 7 Operating lease liabilities 94 90 Other current liabilities 170 139 Long-term debt 122 107 Defined benefit postretirement plan obligations 25 26 Long-term operating lease liabilities 598 575 Deferred credits and other liabilities 86 93 Total liabilities classified as held for sale $ 1,749 $ 1,748

Master Limited Partnership (Tab

Master Limited Partnership (Tables)	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Noncontrolling Interest	As a result of equity transactions of MPLX and ANDX, we are required to adjust non-controlling interest and additional paid-in capital. Changes in MPC’s additional paid-in capital resulting from changes in its ownership interest in MPLX and ANDX were as follows: (In millions) 2020 2019 2018 Increase due to the issuance of MPLX common units and general partner units to MPC $ — $ — $ 1,114 Increase due to GP/IDR Exchange — — 1,808 Increase (decrease) due to the issuance of MPLX & ANDX common units (27) (51) 6 Tax impact (14) (633) (571) Increase (decrease) in MPC's additional paid-in capital, net of tax $ (41) $ (684) $ 2,357

Impairments (Tables)

Impairments (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Details of Impairment of Long-Lived Assets Held and Used by Asset	The table below provides information related to the impairments recognized during 2020 and 2019, along with the location of these impairments within the consolidated statements of income. (In millions) Income Statement Line 2020 2019 Goodwill Impairment expense $ 7,394 $ 1,197 Equity method investments Income (loss) from equity method investments 1,315 42 Long-lived assets Impairment expense (a) 1,032 — Total impairments $ 9,741 $ 1,239

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Components of the Fair Value of Consideration Transferred	The components of the fair value of consideration transferred are as follows: (In millions) Fair value of MPC shares issued $ 19,766 Cash payment to Andeavor stockholders 3,486 Cash settlement of non-employee director units 7 Fair value of converted equity awards 203 Total fair value of consideration transferred $ 23,462
Business Acquisition, Pro Forma Information	The following unaudited pro forma financial information presents consolidated results assuming the Andeavor acquisition occurred on January 1, 2017. (In millions) 2018 Sales and other operating revenues $ 131,921 Net income attributable to MPC 4,218

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Summarized Balance Sheet Information of VIEs	The following table presents balance sheet information for the assets and liabilities of MPLX, which are included in our balance sheets. (In millions) December 31, December 31, Assets Cash and cash equivalents $ 15 $ 15 Receivables, less allowance for doubtful accounts 478 615 Inventories 118 110 Other current assets 67 110 Assets held for sale 188 — Equity method investments 4,036 5,275 Property, plant and equipment, net 21,418 22,174 Goodwill 7,657 9,536 Right of use assets 309 365 Other noncurrent assets 1,006 1,323 Liabilities Accounts payable $ 468 $ 744 Payroll and benefits payable 4 5 Accrued taxes 76 80 Debt due within one year 764 9 Operating lease liabilities 63 66 Liabilities held for sale 101 — Other current liabilities 297 259 Long-term debt 19,375 19,704 Deferred income taxes 12 12 Long-term operating lease liabilities 244 302 Deferred credits and other liabilities 437 409

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	Transactions with related parties were as follows: (In millions) 2020 2019 2018 Sales to related parties $ 123 $ 91 $ 14 Purchases from related parties 738 763 610

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Summary of Earnings Per Common Share	Since MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities, we have calculated our earnings (loss) per share using the two-class method. Diluted income (loss) per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive. (In millions, except per share data) 2020 2019 2018 Income (loss) from continuing operations, net of tax $ (11,182) $ 2,449 $ 2,933 Less: Net income (loss) attributable to noncontrolling interest (151) 618 826 Net income allocated to participating securities 1 1 1 Income (loss) from continuing operations available to common stockholders (11,032) 1,830 2,106 Income from discontinued operations, net of tax 1,205 806 673 Income (loss) available to common stockholders $ (9,827) $ 2,636 $ 2,779 Weighted average common shares outstanding: Basic 649 659 518 Effect of dilutive securities — 5 8 Diluted 649 664 526 Income (loss) available to common stockholders per share: Basic: Continuing operations $ (16.99) $ 2.78 $ 4.06 Discontinued operations 1.86 1.22 1.30 Net income (loss) per share $ (15.13) $ 4.00 $ 5.36 Diluted: Continuing operations $ (16.99) $ 2.76 $ 4.00 Discontinued operations 1.86 1.21 1.28 Net income (loss) per share $ (15.13) $ 3.97 $ 5.28
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table summarizes the shares that were anti-dilutive, and therefore, were excluded from the diluted share calculation. (In millions) 2020 2019 2018 Shares issuable under stock-based compensation plans 11 3 —

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Share Repurchases	Total share repurchases were as follows for the respective periods: (In millions, except per share data) 2020 2019 2018 Number of shares repurchased — 34 47 Cash paid for shares repurchased $ — $ 1,950 $ 3,287 Average cost per share $ — $ 58.87 $ 69.46

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Income From Operations Attributable To Operating Segments	Segment income from operations represents income (loss) from operations attributable to the reportable segments. Corporate administrative expenses, except for those attributable to MPLX, and costs related to certain non-operating assets are not allocated to the Refining & Marketing segment. In addition, certain items that affect comparability (as determined by the chief operating decision maker (“CODM”)) are not allocated to the reportable segments. Assets by segment are not a measure used to assess the performance of the company by the CODM and thus are not reported in our disclosures. (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2020 Revenues: Third party (a) $ 66,180 $ 3,599 $ 69,779 Intersegment 67 4,839 4,906 Segment revenues $ 66,247 $ 8,438 $ 74,685 Segment income from operations $ (5,189) $ 3,708 $ (1,481) Supplemental Data Depreciation and amortization (b) 1,857 1,353 3,210 Capital expenditures and investments (c) 1,170 1,398 2,568 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2019 Revenues: Third party (a) $ 107,305 $ 3,843 $ 111,148 Intersegment 103 4,917 5,020 Segment revenues $ 107,408 $ 8,760 $ 116,168 Segment income from operation $ 2,856 $ 3,594 $ 6,450 Supplemental Data Depreciation and amortization (b) 1,780 1,267 3,047 Capital expenditures and investments (c) 2,045 3,290 5,335 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2018 Revenues: Third party (a) $ 82,755 $ 3,331 $ 86,086 Intersegment 66 3,329 3,395 Segment revenues $ 82,821 $ 6,660 $ 89,481 Segment income from operations $ 2,654 $ 2,752 $ 5,406 Supplemental Data Depreciation and amortization (b) 1,207 885 2,092 Capital expenditures and investments (c) 1,077 2,630 3,707 (a) Includes Refining & Marketing sales to Speedway (as discussed above) and related party sales. See Note 10 for additional information. (b) Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other items not allocated to segments. (c) Includes changes in capital expenditure accruals and investments in affiliates.
Reconciliation Of Segment Income From Operations To Income Before Income Taxes	The following reconciles segment income (loss) from operations to income (loss) from continuing operations before income taxes as reported in the consolidated statements of income: (In millions) 2020 2019 2018 Segment income (loss) from operations $ (1,481) $ 6,450 $ 5,406 Corporate (a) (800) (833) (528) Items not allocated to segments: Impairments (b) (9,741) (1,239) 9 Restructuring expenses (c) (367) — — Litigation 84 (22) — Gain on sale of assets 66 — — Transaction-related costs (d) (8) (153) (197) Equity method investment restructuring gains (e) — 259 — Income (loss) from continuing operations (12,247) 4,462 4,690 Net interest and other financial costs 1,365 1,229 993 Income (loss) from continuing operations before income taxes $ (13,612) $ 3,233 $ 3,697 (a) Corporate consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. Corporate includes corporate costs of $26 million, $28 million and $26 million for 2020, 2019 and 2018, respectively, that are no longer allocable to Speedway under discontinued operations accounting. (b) 2020 reflects impairments of goodwill, equity method investments and long lived assets. 2019 reflects impairments of goodwill and equity method investments. See Note 7. 2018 includes MPC’s share of gains from the sale of assets remaining from the Sandpiper pipeline project, which was cancelled and impaired in 2016. (c) See Note 4. (d) 2020 and 2019 includes costs incurred in connection with the Midstream strategic review and other related efforts. Both 2019 and 2018 include employee severance, retention and other costs related to the acquisition of Andeavor. Effective October 1, 2019, we have discontinued reporting Andeavor transaction-related costs as one year has passed since the acquisition and these costs are immaterial. Costs incurred in connection with the Speedway separation are included in discontinued operations. See Note 5.
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures	The following reconciles segment capital expenditures and investments to total capital expenditures: (In millions) 2020 2019 2018 Segment capital expenditures and investments $ 2,568 $ 5,335 $ 3,707 Less investments in equity method investees 485 1,064 409 Plus items not allocated to segments: Corporate 80 100 77 Capitalized interest 106 137 80 Total capital expenditures (a) $ 2,269 $ 4,508 $ 3,455 (a) Includes changes in capital expenditure accruals. See Note 24 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.

Net Interest and Other Financ_2

Net Interest and Other Financial Costs (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Net Interest And Other Financial Income (Costs)	Net interest and other financial costs were as follows: (In millions) 2020 2019 2018 Interest income $ (9) $ (40) $ (87) Interest expense 1,462 1,389 1,025 Interest capitalized (129) (158) (80) Pension and other postretirement non-service costs (a) 11 4 53 (Gain) loss on extinguishment of debt (9) — 64 Other financial costs 39 34 18 Net interest and other financial costs $ 1,365 $ 1,229 $ 993

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Components Of Income Tax Provisions (Benefits)	The provision (benefit) for income taxes from continuing operations consisted of: (In millions) 2020 2019 2018 Current: Federal $ (2,267) $ (52) $ 674 State and local 69 28 54 Foreign 9 1 22 Total current (2,189) (23) 750 Deferred: Federal 90 742 (119) State and local (347) 56 149 Foreign 16 9 (16) Total deferred (241) 807 14 Income tax provision (benefit) $ (2,430) $ 784 $ 764
Reconciliation Of Federal Statutory Income Tax Rate	A reconciliation of the federal statutory income tax rate to the effective tax rate applied to income (loss) from continuing operations before income taxes follows: 2020 2019 2018 Federal statutory rate 21 % 21 % 21 % State and local income taxes, net of federal income tax effects 2 2 5 Goodwill impairment (8) 5 — Noncontrolling interests — (4) (5) Legislation 4 — — Other (1) — — Effective tax rate applied to income (loss) from continuing operations before income taxes 18 % 24 % 21 %
Components Of Deferred Tax Assets And Liabilities	Deferred tax assets and liabilities resulted from the following: December 31, (In millions) 2020 2019 Deferred tax assets: Employee benefits $ 647 $ 693 Environmental remediation 95 99 Finance lease obligations 103 105 Debt financing 6 17 Operating lease liabilities 453 498 Net operating loss carryforwards 232 18 Foreign currency — 15 Tax credit carryforwards 19 14 Other 74 57 Total deferred tax assets 1,629 1,516 Deferred tax liabilities: Property, plant and equipment 3,195 3,301 Inventories 800 652 Investments in subsidiaries and affiliates 3,331 3,114 Goodwill and other intangibles 34 304 Right of use assets 451 498 Other 18 19 Total deferred tax liabilities 7,829 7,888 Net deferred tax liabilities $ 6,200 $ 6,372
Components Of Net Deferred Tax Liabilities Classified In Consolidated Balance Sheets	Net deferred tax liabilities were classified in the consolidated balance sheets as follows: December 31, (In millions) 2020 2019 Assets: Other noncurrent assets $ 3 $ 20 Liabilities: Deferred income taxes (a) 6,203 6,392 Net deferred tax liabilities $ 6,200 $ 6,372
Summary Of Activity In Unrecognized Tax Benefits	The following table summarizes the activity in unrecognized tax benefits: (In millions) 2020 2019 2018 January 1 balance $ 32 $ 211 $ 19 Additions for tax positions of prior years 12 2 — Reductions for tax positions of prior years (18) (2) (5) Settlements (3) (19) — Statute of limitations — (160) (12) Acquired from Andeavor — — 209 December 31 balance $ 23 $ 32 $ 211

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Summary Of Inventories	December 31, (In millions) 2020 2019 Crude oil $ 2,588 $ 3,472 Refined products 4,478 5,359 Materials and supplies 933 973 Total $ 7,999 $ 9,804

Equity Method Investments (Tabl

Equity Method Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Schedule Of Equity Method Investments	Ownership as of Carrying value at December 31, December 31, (Dollars in millions) VIE 2020 2020 2019 Refining & Marketing The Andersons Marathon Holdings LLC 50% $ 159 $ 177 Watson Cogeneration Company 51% 25 26 Refining & Marketing Total $ 184 $ 203 Midstream MPLX Andeavor Logistics Rio Pipeline LLC X 67% $ 194 $ 202 Centrahoma Processing LLC 40% 145 153 Explorer Pipeline Company 25% 72 83 Illinois Extension Pipeline Company, L.L.C 35% 254 265 LOOP LLC 41% 252 238 MarEn Bakken Company LLC 25% 465 481 MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. X 67% 307 302 MarkWest Utica EMG, L.L.C. X 57% 698 1,984 Minnesota Pipe Line Company, LLC 17% 188 190 Rendezvous Gas Services, L.L.C. X 78% 159 170 Sherwood Midstream Holdings LLC X 51% 148 157 Sherwood Midstream LLC X 50% 557 537 Whistler Pipeline LLC X 38% 185 134 Wink to Webster Pipeline LLC (a) X —% — 126 W2W Holdings LLC (a) X 50% 72 — Other (b) X 340 253 MPLX Total $ 4,036 $ 5,275 MPC-Retained Capline Pipeline Company LLC X 33% $ 390 $ 374 Crowley Coastal Partners, LLC X 50% 190 188 Gray Oak Pipeline, LLC 25% 342 298 LOOP LLC 10% 63 59 South Texas Gateway Terminal LLC 25% 168 85 Other (b) X 49 86 MPC-Retained Total $ 1,202 $ 1,090 Midstream Total $ 5,238 $ 6,365 Total $ 5,422 $ 6,568 (a) During 2020, MPLX contributed its ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC. (b) Some investments included within “Other” have been deemed to be VIEs.
Summarized Financial Information For Equity Method Investees	Summarized financial information for all equity method investments in affiliated companies, combined, was as follows: (In millions) 2020 2019 2018 Income statement data: Revenues and other income $ 3,013 $ 3,282 $ 3,092 Income from operations 599 1,176 1,105 Net income 454 987 972 Balance sheet data – December 31: Current assets $ 1,298 $ 1,195 Noncurrent assets 17,697 16,362 Current liabilities 754 997 Noncurrent liabilities 4,736 2,769

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Summary Of Property, Plant And Equipment	(In millions) Estimated December 31, 2020 2019 Refining & Marketing (a) 4 -30 years $ 30,306 $ 29,101 Midstream 1 -61 years 27,677 27,193 Corporate 4 - 40 years 1,356 1,292 Total 59,339 57,586 Less accumulated depreciation (b) 20,304 16,716 Property, plant and equipment, net $ 39,035 $ 40,870 (a) Recast to include the direct dealer business. See Note 13 for additional information.

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for 2019 and 2020 were as follows: (In millions) Refining & Marketing (a) Midstream Total Balance at January 1, 2019 $ 5,511 $ 10,323 $ 15,834 Acquisitions 38 — 38 Purchase price allocation adjustments 584 408 992 Impairments (b) — (1,197) (1,197) Dispositions — (17) (17) Balance at December 31, 2019 $ 6,133 $ 9,517 $ 15,650 Transfers 8 (8) — Impairments (b) (5,580) (1,814) (7,394) Balance at December 31, 2020 $ 561 $ 7,695 $ 8,256 (a) Recast to include the direct dealer business. See Note 13 for additional information. (b) See Note 7.
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	Our definite lived intangible assets as of December 31, 2020 and 2019 are as shown below. December 31, 2020 December 31, 2019 (In millions) Gross Accumulated Amortization Net Gross Accumulated Amortization Net Customer contracts and relationships $ 3,359 $ 1,119 $ 2,240 $ 3,271 $ 612 $ 2,659 Brand rights and tradenames 100 35 65 100 20 80 Royalty agreements 133 87 46 133 78 55 Other 36 27 9 36 24 12 Total $ 3,628 $ 1,268 $ 2,360 $ 3,540 $ 734 $ 2,806
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated future amortization expense for the next five years related to the intangible assets at December 31, 2020 is as follows: (In millions) 2021 $ 347 2022 346 2023 330 2024 277 2025 257

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Assets and Liabilities Accounted for at Fair Value on Recurring Basis	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of December 31, 2020 and 2019 by fair value hierarchy level. We have elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty, including any related cash collateral as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the following tables. December 31, 2020 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 82 $ 6 $ — $ (80) $ 8 $ 31 Liabilities: Commodity contracts $ 81 $ 10 $ — $ (91) $ — $ — Embedded derivatives in commodity contracts — — 63 — 63 — December 31, 2019 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 57 $ 6 $ — $ (55) $ 8 $ 73 Liabilities: Commodity contracts $ 95 $ 11 $ — $ (106) $ — $ — Embedded derivatives in commodity contracts — — 60 — 60 — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of December 31, 2020, cash collateral of $11 million was netted with mark-to-market liabilities. As of December 31, 2019, cash collateral of $51 million was netted with mark-to-market derivative liabilities. (b) We have no derivative contracts which are subject to master netting arrangements reflected gross on the balance sheet.
Reconciliation of Net Beginning and Ending Balances Recorded for Net Assets and Liabilities Classified as Level 3	The following is a reconciliation of the beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. (In millions) 2020 2019 Beginning balance $ 60 $ 61 Unrealized and realized losses included in net income 9 5 Settlements of derivative instruments (6) (6) Ending balance $ 63 $ 60 The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: $ 4 $ 5

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Derivative Instruments [Abstract]
Classification of Fair Values of Derivative Instruments, Excluding Cash Collateral	The following table presents the fair value of derivative instruments as of December 31, 2020 and 2019 and the line items in the balance sheets in which the fair values are reflected. The fair value amounts below are presented on a gross basis and do not reflect the netting of asset and liability positions permitted under the terms of our master netting arrangements including cash collateral on deposit with, or received from, brokers. We offset the recognized fair value amounts for multiple derivative instruments executed with the same counterparty in our financial statements when a legal right of offset exists. As a result, the asset and liability amounts below will not agree with the amounts presented in our consolidated balance sheets. (In millions) December 31, 2020 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 88 $ 91 Other current liabilities (a) — 7 Deferred credits and other liabilities (a) — 56 (In millions) December 31, 2019 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 63 $ 106 Other current liabilities (a) — 5 Deferred credits and other liabilities (a) — 55 (a) Includes embedded derivatives.
Schedule of Notional Amounts of Outstanding Derivative Positions	The table below summarizes open commodity derivative contracts for crude oil, refined products and blending products as of December 31, 2020. Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 81.9% 17,474 11,197 Refined products 89.0% 13,923 9,354 Blending products 100.0% 3,206 3,987 Soybean oil 100.0% 558 1,117 (a) Included in exchange-traded are spread contracts in thousands of barrels: Refined products - 935 long and 455 short
Effect of Commodity Derivative Instruments in Statements of Income	The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income: (In millions) Gain (Loss) Income Statement Location 2020 2019 2018 Sales and other operating revenues $ 72 $ (19) $ 13 Cost of revenues 34 (77) (59) Other income 1 — — Total $ 107 $ (96) $ (46)

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Instrument [Line Items]
Outstanding Borrowings	Our outstanding borrowings at December 31, 2020 and 2019 consisted of the following: (In millions) December 31, December 31, Marathon Petroleum Corporation: Commercial paper $ 1,024 $ — Senior notes 9,849 8,474 Notes payable 1 1 Finance lease obligations 634 574 MPLX LP: Bank revolving credit facility 175 — Term loan facility — 1,000 Senior notes 20,350 19,100 Finance lease obligations 11 19 Total debt $ 32,044 $ 29,168 Unamortized debt issuance costs (154) (134) Unamortized (discount) premium, net (306) (310) Amounts due within one year (2,854) (704) Total long-term debt due after one year $ 28,730 $ 28,020
Schedule Of Debt Payments	Principal maturities of long-term debt, excluding finance lease obligations, as of December 31, 2020 for the next five years are as follows: (In millions) 2021 $ 1,750 2022 1,500 2023 3,600 2024 2,376 2025 2,950
Schedule of Line of Credit Facilities	(Dollars in millions) Total Outstanding Outstanding Available Weighted Expiration MPC, excluding MPLX MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2021 MPC 364-day bank revolving credit facility 1,000 — — 1,000 — April 2021 MPC bank revolving credit facility (a) 5,000 — 1 4,999 — October 2023 MPC trade receivables securitization facility (b) 750 — — 750 — July 2021 MPLX MPLX bank revolving credit facility (c) 3,500 175 — 3,325 1.36 July 2024 (a) Borrowed $4.225 billion and repaid $4.225 billion during the year ended December 31, 2020. (b) Borrowed $3.550 billion and repaid $3.550 billion during the year ended December 31, 2020. Availability under our $750 million trade receivables facility is a function of eligible trade receivables, which will be lower in a sustained lower price environment for refined products. (c) Borrowed $3.815 billion and repaid $3.640 billion during the year ended December 31, 2020.
Marathon Petroleum Corporation | Senior Notes
Debt Instrument [Line Items]
Outstanding Borrowings	December 31, (In millions) 2020 2019 Marathon Petroleum Corporation: Senior notes, 3.400% due December 2020 $ — $ 650 Senior notes, 5.125% due March 2021 1,000 1,000 Senior notes, 5.375% due October 2022 — 337 Senior notes, 4.500% due May 2023 1,250 — Senior notes, 4.750% due December 2023 614 614 Senior notes, 5.125% due April 2024 241 241 Senior notes, 3.625% due September 2024 750 750 Senior notes, 4.700% due May 2025 1,250 — Senior notes, 5.125% due December 2026 719 719 Senior notes, 3.800% due April 2028 496 496 Senior notes, 6.500% due March 2041 1,250 1,250 Senior notes, 4.750% due September 2044 800 800 Senior notes, 5.850% due December 2045 250 250 Senior notes, 4.500% due April 2048 498 498 Andeavor senior notes, 3.800% - 5.375% due 2022 - 2048 331 469 Senior notes, 5.000%, due September 2054 400 400 Total $ 9,849 $ 8,474
MPLX | Senior Notes
Debt Instrument [Line Items]
Outstanding Borrowings	December 31, (In millions) 2020 2019 MPLX LP: Floating rate notes due September 2021 $ — $ 1,000 Floating rate notes due September 2022 1,000 1,000 Senior notes, 6.250% due October 2022 — 266 Senior notes, 3.500% due December 2022 486 486 Senior notes, 3.375% due March 2023 500 500 Senior notes, 4.500% due July 2023 989 989 Senior notes, 6.375% due May 2024 — 381 Senior notes, 4.875% due December 2024 1,149 1,149 Senior notes, 5.250% due January 2025 708 708 Senior notes, 4.000% due February 2025 500 500 Senior notes, 4.875% due June 2025 1,189 1,189 MarkWest senior notes, 4.500% - 4.875% due 2023 - 2025 23 23 Senior notes, 1.750% due March 2026 1,500 — Senior notes, 4.125% due March 2027 1,250 1,250 Senior notes, 4.250% due December 2027 732 732 Senior notes, 4.000% due March 2028 1,250 1,250 Senior notes, 4.800% due February 2029 750 750 Senior notes, 2.650% due August 2030 1,500 — Senior notes, 4.500% due April 2038 1,750 1,750 Senior notes, 5.200% due March 2047 1,000 1,000 Senior notes, 5.200% due December 2047 487 487 ANDX senior notes, 3.500% - 5.250% due 2022 - 2047 87 190 Senior notes, 4.700% due April 2048 1,500 1,500 Senior notes, 5.500% due February 2049 1,500 1,500 Senior notes, 4.900% due April 2058 500 500 Total $ 20,350 $ 19,100

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	As discussed in Notes 1 and 13, the presentation of Refining & Marketing segment revenues reflects changes associated with the expected sale of Speedway and our new reportable segments. The following table presents our revenues disaggregated by segment and product line: (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2020 Refined products $ 61,648 $ 641 $ 62,289 Crude oil 4,023 — 4,023 Midstream services and other 509 2,958 3,467 Sales and other operating revenues $ 66,180 $ 3,599 $ 69,779 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2019 Refined products $ 102,316 $ 818 $ 103,134 Crude oil 4,402 — 4,402 Midstream services and other 587 3,025 3,612 Sales and other operating revenues $ 107,305 $ 3,843 $ 111,148 (In millions) Refining & Marketing Midstream Total Year Ended December 31, 2018 Refined products $ 78,952 $ 945 $ 79,897 Crude oil 3,345 — 3,345 Midstream services and other 458 2,386 2,844 Sales and other operating revenues $ 82,755 $ 3,331 $ 86,086

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Summary of Supplemental Cash Flow Information	(In millions) 2020 2019 2018 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 1,235 $ 1,168 $ 887 Net income taxes paid to (received from) taxing authorities (179) 491 424 Cash paid for amounts included in the measurement of lease liabilities Payments on operating leases (a) 651 642 — Interest payments under finance lease obligations (a) 25 28 — Net cash provided by financing activities included: Principal payments under finance lease obligations (a) 66 48 — Non-cash investing and financing activities: Capital leases — — 172 Right of use assets obtained in exchange for new operating lease obligations (a) 343 329 — Right of use assets obtained in exchange for new finance lease obligations (a) 110 80 — Contribution of assets (b) — 266 — Fair value of assets acquired (c) — 525 — Acquisition: Fair value of MPC shares issued — — 19,766 Fair value of converted equity awards — — 203 (a) Disclosure added in 2019 following the adoption of ASC 842. (b) 2019 includes the contribution of net assets to TAMH and Capline LLC. See Note 17.
Schedule of Cash and Cash Equivalents	(In millions) December 31, December 31, Cash and cash equivalents (a) $ 415 $ 1,393 Restricted cash (b) 1 2 Cash, cash equivalents and restricted cash $ 416 $ 1,395 (a) Excludes $140 million and $134 million of cash included in assets held for sale representing Speedway store cash.
Schedule Of Reconciliation Of Additions To Property Plant And Equipment To Total Capital Expenditures	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 expenditures: (In millions) 2020 2019 2018 Additions to property, plant and equipment per the consolidated statements of cash flows $ 2,787 $ 4,810 $ 3,179 Asset retirement expenditures — 1 8 Increase (decrease) in capital accruals (518) (303) 268 Total capital expenditures $ 2,269 $ 4,508 $ 3,455

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Changes in Accumulated Other Comprehensive Loss by Component	The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2018 $ (132) $ (23) $ 2 $ 9 $ (144) Other comprehensive income (loss) before reclassifications, net of tax of $(52) (71) (92) — 1 (162) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (45) — — — (45) – actuarial loss (a) 22 (1) — — 21 – settlement loss (a) 9 — — — 9 Other — — (1) (4) (5) Tax effect 5 — — 1 6 Other comprehensive loss (80) (93) (1) (2) (176) Balance as of December 31, 2019 $ (212) $ (116) $ 1 $ 7 $ (320) (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2019 $ (212) $ (116) $ 1 $ 7 $ (320) Other comprehensive income (loss) before reclassifications, net of tax of $(65) (136) (67) — 4 (199) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (45) — — — (45) – actuarial loss (a) 36 3 — — 39 – settlement loss (a) 22 — — — 22 Other — — — (6) (6) Tax effect (3) (1) — 1 (3) Other comprehensive loss (126) (65) — (1) (192) Balance as of December 31, 2020 $ (338) $ (181) $ 1 $ 6 $ (512) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 26.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Contribution Plan Disclosures	Benefits for service beginning January 1, 2010 and beginning on January 1, 2016 are based on a cash balance formula with an annual percentage of eligible pay credited based upon age and years of service or at a flat rate of eligible pay, depending on covered employee group. Substantially all of our employees also accrue benefits under a defined contribution plan. (In millions) 2020 2019 2018 Cash balance weighted average interest crediting rates 3.00 % 3.18 % 3.00 %
Summary Of Defined Benefit Plans With Accumulated Benefit Obligations In Excess Of Plan Assets	The following summarizes our defined benefit pension plans that have accumulated benefit obligations in excess of plan assets. December 31, (In millions) 2020 2019 Projected benefit obligations $ 3,671 $ 3,220 Accumulated benefit obligations 3,369 3,013 Fair value of plan assets 2,621 2,531
Summary Of Projected Benefit Obligations And Funded Status For Defined Benefit Pension And Other Postretirement Plans	The following summarizes the projected benefit obligations and funded status for our defined benefit pension and other postretirement plans: Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Change in benefit obligations: Benefit obligations at January 1 $ 3,220 $ 2,761 $ 1,020 $ 874 Service cost 302 234 35 31 Interest cost 98 107 32 37 Actuarial loss (a) 373 400 83 123 Benefits paid (322) (282) (39) (43) Plan amendments — — — (2) Benefit obligations at December 31 3,671 3,220 1,131 1,020 Change in plan assets: Fair value of plan assets at January 1 2,531 2,090 — — Actual return on plan assets 327 435 — — Employer contributions 85 288 39 43 Benefits paid from plan assets (322) (282) (39) (43) Fair value of plan assets at December 31 2,621 2,531 — — Funded status of plans at December 31 $ (1,050) $ (689) $ (1,131) $ (1,020) Amounts recognized in the consolidated balance sheets: Current liabilities $ (9) $ (47) $ (51) $ (46) Noncurrent liabilities (1,041) (642) (1,080) (974) Accrued benefit cost $ (1,050) $ (689) $ (1,131) $ (1,020) Pretax amounts recognized in accumulated other comprehensive loss: (b) Net actuarial loss $ 699 $ 577 $ 219 $ 139 Prior service cost (credit) (204) (250) 32 32 (a) The primary driver of the actuarial loss for the pension plans in 2020 and 2019 was the decrease in interest rates. The plans also saw moderate losses related to demographic experience in each year. (b) Amounts exclude those related to LOOP and Explorer, equity method investees with defined benefit pension and postretirement plans for which net losses of $16 million and less than $1 million were recorded in accumulated other comprehensive loss in 2020, reflecting our ownership share.
Components of Net Periodic Benefit Costs	The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive loss for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits (In millions) 2020 2019 2018 2020 2019 2018 Components of net periodic benefit cost: Service cost $ 283 $ 218 $ 147 $ 35 $ 31 $ 30 Interest cost 98 107 83 32 37 30 Expected return on plan assets (133) (127) (109) — — — Amortization – prior service credit (45) (45) (33) — — (3) – actuarial loss 36 22 31 3 — 1 – settlement loss 20 9 53 — — — Net periodic benefit cost (a) $ 259 $ 184 $ 172 $ 70 $ 68 $ 58 Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax): Actuarial (gain) loss $ 179 $ 92 $ 65 $ 83 $ 123 $ (72) Prior service cost (credit) — — (90) — (2) 34 Amortization of actuarial loss (56) (31) (84) (3) — (1) Amortization of prior service credit 45 45 33 — — 3 Total recognized in other comprehensive loss $ 168 $ 106 $ (76) $ 80 $ 121 $ (36) Total recognized in net periodic benefit cost and other comprehensive loss $ 427 $ 290 $ 96 $ 150 $ 189 $ 22 (a) Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Loss (Pretax)	The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive loss for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits (In millions) 2020 2019 2018 2020 2019 2018 Components of net periodic benefit cost: Service cost $ 283 $ 218 $ 147 $ 35 $ 31 $ 30 Interest cost 98 107 83 32 37 30 Expected return on plan assets (133) (127) (109) — — — Amortization – prior service credit (45) (45) (33) — — (3) – actuarial loss 36 22 31 3 — 1 – settlement loss 20 9 53 — — — Net periodic benefit cost (a) $ 259 $ 184 $ 172 $ 70 $ 68 $ 58 Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax): Actuarial (gain) loss $ 179 $ 92 $ 65 $ 83 $ 123 $ (72) Prior service cost (credit) — — (90) — (2) 34 Amortization of actuarial loss (56) (31) (84) (3) — (1) Amortization of prior service credit 45 45 33 — — 3 Total recognized in other comprehensive loss $ 168 $ 106 $ (76) $ 80 $ 121 $ (36) Total recognized in net periodic benefit cost and other comprehensive loss $ 427 $ 290 $ 96 $ 150 $ 189 $ 22 (a) Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
Plan Assumptions	The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2020, 2019 and 2018. Pension Benefits Other Benefits 2020 2019 2018 2020 2019 2018 Weighted-average assumptions used to determine benefit obligation: Discount rate 2.44 % 3.08 % 4.21 % 2.55 % 3.00 % 4.26 % Rate of compensation increase 5.70 % 4.90 % 5.00 % 5.70 % 4.90 % 5.00 % Weighted-average assumptions used to determine net periodic benefit cost: Discount rate 3.00 % 4.07 % 3.89 % 3.23 % 4.30 % 3.72 % Expected long-term return on plan assets 5.75 % 6.00 % 6.15 % — % — % — % Rate of compensation increase 5.70 % 4.90 % 4.80 % 5.70 % 4.90 % 5.00 %
Assumed Health Care Cost Trend Rates	The following summarizes the assumed health care cost trend rates. December 31, 2020 2019 2018 Health care cost trend rate assumed for the following year: Medical: Pre-65 6.00 % 6.20 % 6.80 % Prescription drugs 7.00 % 8.10 % 9.50 % Rate to which the cost trend rate is assumed to decline (the ultimate trend rate): Medical: Pre-65 4.50 % 4.50 % 4.50 % Prescription drugs 4.50 % 4.50 % 4.50 % Year that the rate reaches the ultimate trend rate: Medical: Pre-65 2028 2027 2027 Prescription drugs 2028 2027 2027
Fair Values Of Defined Benefit Pension Plan Assets	The following tables present the fair values of our defined benefit pension plans’ assets, by level within the fair value hierarchy, as of December 31, 2020 and 2019. December 31, 2020 (In millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 23 $ — $ 23 Equity: Common stocks 51 3 — 54 Mutual funds 353 — — 353 Pooled funds — 794 — 794 Fixed income: Corporate — 746 — 746 Government 327 128 — 455 Pooled funds — 131 — 131 Private equity — — 23 23 Real estate — — 20 20 Other — 3 19 22 Total investments, at fair value $ 731 $ 1,828 $ 62 $ 2,621 December 31, 2019 (In millions) Level 1 Level 2 Level 3 Total Cash and cash equivalents $ — $ 22 $ — $ 22 Equity: Common stocks 125 135 — 260 Mutual funds 188 — — 188 Pooled funds — 442 — 442 Fixed income: Corporate 160 815 — 975 Government 113 217 — 330 Pooled funds — 229 — 229 Private equity — — 30 30 Real estate — — 24 24 Other 58 (46) 19 31 Total investments, at fair value $ 644 $ 1,814 $ 73 $ 2,531
Reconciliation Of Beginning And Ending Balances Of Plan Assets Classified As Level 3	The following is a reconciliation of the beginning and ending balances recorded for plan assets classified as Level 3 in the fair value hierarchy: 2020 (In millions) Private Equity Real Estate Other Beginning balance $ 30 $ 24 $ 19 Actual return on plan assets: Realized 6 1 — Unrealized (4) (3) — Purchases — 1 — Sales (9) (3) — Ending balance $ 23 $ 20 $ 19 2019 (In millions) Private Equity Real Estate Other Beginning balance $ 41 $ 29 $ 18 Actual return on plan assets: Realized 5 2 — Unrealized (3) (2) 1 Purchases 1 1 — Sales (14) (6) — Ending balance $ 30 $ 24 $ 19
Estimated Future Benefit Payment	The following gross benefit payments, which reflect expected future service, as appropriate, are expected to be paid in the years indicated. (In millions) Pension Benefits Other Benefits 2021 $ 185 $ 52 2022 189 52 2023 194 52 2024 206 52 2025 212 53 2026 through 2030 1,172 280
Multi Employer Pension Plan	Our participation in this plan for 2020, 2019 and 2018 is outlined in the table below. The “EIN” column provides the Employee Identification Number for the plan. The most recent Pension Protection Act zone status available in 2020 and 2019 is for the plan’s year ended December 31, 2019 and December 31, 2018, respectively. The zone status is based on information that we received from the plan and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than 65 percent funded. The “FIP/RP Status Pending/Implemented” column indicates a financial improvement plan or a rehabilitation plan has been implemented. The last column lists the expiration date of the collective-bargaining agreement to which the plan is subject. There have been no significant changes that affect the comparability of 2020, 2019 and 2018 contributions. Our portion of the contributions does not make up more than five percent of total contributions to the plan. Pension FIP/RP Status MPC Contributions In millions ) Surcharge Expiration Date of Pension Fund EIN 2020 2019 2020 2019 2018 Central States, Southeast and Southwest Areas Pension Plan (a) 366044243 Red Red Implemented $ 5 $ 4 $ 4 No January 31, 2024 (a) This agreement has a minimum contribution requirement of $338 per week per employee for 2021. A total of 275 employees participated in the plan as of December 31, 2020.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table reflects activity related to our stock-based compensation arrangements, including the converted awards related to the acquisition of Andeavor: (In millions) 2020 2019 2018 Stock-based compensation expense $ 100 $ 153 $ 127 Tax benefit recognized on stock-based compensation expense 25 35 31 Cash received by MPC upon exercise of stock option awards 11 10 24 Tax (expense)/benefit received for tax deductions for stock awards exercised 16 (3) 14
Weighted Average Assumptions Used To Value Stock Options Awards	The Black Scholes option-pricing model values used to value stock option awards granted were determined based on the following weighted average assumptions: 2020 2019 2018 Weighted average exercise price per share $ 28.78 $ 61.92 $ 67.71 Expected life in years 5.9 6.0 6.2 Expected volatility 39 % 32 % 34 % Expected dividend yield 4.7 % 3.4 % 3.0 % Risk-free interest rate 0.6 % 2.4 % 2.7 % Weighted average grant date fair value of stock option awards granted $ 7.40 $ 13.65 $ 17.21
Summary of Stock Option Award Activity	The following is a summary of our common stock option activity in 2020: Number of Weighted Average Exercise Price Weighted Average Remaining Contractual Terms (in years) Aggregate Intrinsic Value (in millions) Outstanding at December 31, 2019 10,018,367 $ 42.55 Granted 2,770,139 28.78 Exercised (1,016,593) 14.15 Forfeited or expired (472,132) 37.77 Outstanding at December 31, 2020 11,299,781 41.95 Vested and expected to vest at December 31, 2020 11,243,905 29.28 5.2 $ 76 Exercisable at December 31, 2020 7,641,774 42.61 3.6 42
Summary of Restricted Stock Award Activity	The following is a summary of restricted stock award activity of our common stock in 2020: Restricted Stock Restricted Stock Units Number of Weighted Number of Weighted Unvested at December 31, 2019 1,349,798 $ 62.20 1,481,746 $ 82.39 Granted 2,463 56.49 3,076,347 22.82 Vested (646,358) 61.58 (823,111) 77.01 Forfeited (125,924) 62.11 (410,658) 27.76 Unvested at December 31, 2020 579,979 62.89 3,324,324 35.34
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity, Vested And Unvested	The following is a summary of the values related to restricted stock and restricted stock unit awards held by MPC employees and non-employee directors: Restricted Stock Restricted Stock Units Intrinsic Value of Awards Vested During the Period (in millions) Weighted Average Grant Date Fair Value of Awards Granted During the Period Intrinsic Value of Awards Vested During the Period (in millions) Weighted Average Grant Date Fair Value of Awards Granted During the Period 2020 $ 18 $ 56.49 $ 59 $ 22.82 2019 32 61.14 120 58.30 2018 49 71.19 39 72.43
Schedule of Performance Unit Awards	The following table presents a summary of the 2020 activity for performance unit awards to be settled in shares: Number of Units Weighted Average Grant Date Fair Value Unvested at December 31, 2019 11,199,500 $ 0.80 Granted 3,360,000 0.89 Vested (3,490,750) 0.89 Forfeited (58,713) 0.75 Unvested at December 31, 2020 11,010,037 0.80
Schedule of Share-based Compensation, Performance Unit Awards, Valuation Assumptions	Performance units to be settled in MPC shares have a grant date fair value calculated using a Monte Carlo valuation model, which requires the input of subjective assumptions. The following table provides a summary of these assumptions: 2020 2019 2018 Risk-free interest rate 0.9 % 2.5 % 2.3 % Look-back period (in years) 2.8 2.8 2.8 Expected volatility 30.4 % 29.7 % 34.0 % Grant date fair value of performance units granted $ 0.89 $ 0.72 $ 0.83

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lease, Cost	Under ASC 842, the components of lease cost are shown below. Lease costs for operating leases are recognized on a straight line basis and are reflected in the income statement based on the leased asset’s use. Lease costs for finance leases are reflected in depreciation and amortization and in net interest and other financial costs. (In millions) 2020 2019 Finance lease cost: Amortization of right of use assets $ 72 $ 59 Interest on lease liabilities 35 37 Operating lease cost 658 660 Variable lease cost 60 68 Short-term lease cost 631 735 Total lease cost $ 1,456 $ 1,559
Supplemental Balance Sheet Disclosures	Supplemental balance sheet data related to leases were as follows: December 31, (In millions) 2020 2019 Operating leases Assets Right of use assets $ 1,521 $ 1,806 Liabilities Operating lease liabilities $ 497 $ 514 Long-term operating lease liabilities 1,014 1,300 Total operating lease liabilities $ 1,511 $ 1,814 Weighted average remaining lease term (in years) 4.8 5.1 Weighted average discount rate 3.68 % 3.91 % Finance leases Assets Property, plant and equipment, gross $ 819 $ 740 Less accumulated depreciation 272 215 Property, plant and equipment, net $ 547 $ 525 Liabilities Debt due within one year $ 69 $ 56 Long-term debt 576 537 Total finance lease liabilities $ 645 $ 593 Weighted average remaining lease term (in years) 10.7 11.6 Weighted average discount rate 5.33 % 6.63 %
Operating & Finance Leases, Liability, Maturity	As of December 31, 2020, 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) Operating Finance 2021 $ 544 $ 91 2022 373 99 2023 243 101 2024 170 84 2025 111 76 2026 and thereafter 224 402 Gross lease payments 1,665 853 Less: imputed interest 154 208 Total lease liabilities $ 1,511 $ 645
Schedule of Future Minimum Rental Payments for Operating Leases	The following is a schedule of minimum future rentals on the non‑cancellable operating leases as of December 31, 2020: (In millions) 2021 $ 186 2022 181 2023 178 2024 174 2025 142 2026 and thereafter 999 Total minimum future rentals $ 1,860
Schedule of Property Subject to or Available for Operating Lease	The following schedule summarizes our investment in assets held for operating lease by major classes as of December 31, 2020 and 2019: December 31, (In millions) 2020 2019 Gathering and transportation $ 990 $ 980 Processing and fractionation 867 855 Terminals 128 83 Land, building and other 15 17 Property, plant and equipment 2,000 1,935 Less accumulated depreciation 430 327 Total property, plant and equipment, net $ 1,570 $ 1,608

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Data [Abstract]
Schedule Of Quarterly Financial Information	As a result of the agreement to sell Speedway, Speedway’s results are reported separately as discontinued operations in our consolidated statements of income for all periods presented. Prior to presentation of Speedway as discontinued operations, Speedway and our retained direct dealer business were the two reporting units within our Retail segment. Beginning with the third quarter of 2020, the direct dealer business is managed as part of the Refining & Marketing segment. The results of the Refining & Marketing segment have been retrospectively adjusted to include the results of the direct dealer business in all periods presented. In accordance with ASC 205, Discontinued Operations, intersegment sales from our Refining & Marketing segment to Speedway are no longer eliminated as intercompany transactions and are now presented within sales and other operating revenue, since we will continue to supply fuel to Speedway subsequent to the sale to 7-Eleven. All periods presented have been retrospectively adjusted to reflect this change. 2020 Quarter Ended (In millions, except per share data) March 31 June 30 September 30 December 31 Sales and other operating revenues $ 22,204 $ 12,195 $ 17,408 $ 17,972 Income (loss) from continuing operations (12,155) 575 (1,057) 390 Income (loss) from continuing operations, net of tax (10,536) 84 (980) 250 Net income (loss) (10,218) 276 (609) 574 Net income (loss) attributable to MPC (9,234) 9 (886) 285 Income (loss) from continuing operations per share (a) : Basic $ (14.74) $ (0.28) $ (1.93) $ (0.06) Diluted (14.74) (0.28) (1.93) (0.06) 2019 Quarter Ended (In millions, except per share data) March 31 June 30 September 30 December 31 Sales and other operating revenues $ 25,349 $ 30,239 $ 27,552 $ 28,008 Income from continuing operations 526 1,698 1,680 558 Income from continuing operations, net of tax 150 1,109 1,113 77 Net income 259 1,367 1,367 262 Net income (loss) attributable to MPC (7) 1,106 1,095 443 Income (loss) from continuing operations per share (a) : Basic $ (0.17) $ 1.28 $ 1.28 $ 0.40 Diluted (0.17) 1.27 1.27 0.40

Description of the Business a_2

Description of the Business and Basis of Presentation (Details) $ in Billions	Dec. 31, 2020Store	Aug. 02, 2020USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of branded outlets	7,100
Number of direct dealer locations	1,090
Speedway | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration | $		$ 21

Summary of Principal Accounti_3

Summary of Principal Accounting Policies (Principal Accounting Policies) (Details)	12 Months Ended
	Dec. 31, 2020
Accounts receivable number of days past-due evaluated for doubtful accounts	180 days
Stock Options
Implied volatility rate weighting (in percentage)	50.00%
Historical volatility rate weighting (in percentage)	50.00%
Minimum
Estimated useful lives (in years)	1 year
Maximum
Estimated useful lives (in years)	61 years
MPC | MPLX
MPC's partnership interest in MLPs (in percentage)	62.00%

Accounting Standards (Details)

Accounting Standards (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accounting Standards Update and Change in Accounting Principle [Abstract]
Receivables, less allowance for doubtful accounts	$ 5,760	$ 7,233
Receivables, allowance for doubtful accounts, current	$ 18	$ 17

Restructuring (Details)

Restructuring (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2020USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 367	$ 0	$ 0
Restructuring reserve to be settled in cash	$ 141			$ 291	[1]
Number of positions eliminated	2,050
Exit and disposal costs
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 195
Restructuring reserve to be settled in cash	103			133
Restructuring reserve, settled without cash	51
Exit and disposal costs | Decommissioning refinery processing units and storage tanks and environmental remediation obligations
Restructuring Cost and Reserve [Line Items]
Restructuring reserve to be settled in cash				130
Employee separation costs
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	172
Restructuring reserve to be settled in cash	38			$ 158
Employee separation costs | MPLX
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 37
[1]	The restructuring reserve was zero until the third quarter of 2020.

Restructuring Reserve (Details)

Restructuring Reserve (Details) $ in Millions	3 Months Ended
	Dec. 31, 2020USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	$ 291	[1]
Adjustments	19
Cash payments	(169)
Restructuring reserve, ending balance	141
Employee separation costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	158
Adjustments	14
Cash payments	(134)
Restructuring reserve, ending balance	38
Exit and disposal costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	133
Adjustments	5
Cash payments	(35)
Restructuring reserve, ending balance	$ 103
[1]	The restructuring reserve was zero until the third quarter of 2020.

Discontinued Operations and A_3

Discontinued Operations and Assets Held for Sale (Details) $ in Billions	Aug. 02, 2020USD ($)
Speedway | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration	$ 21

Discontinued Operations and A_4

Discontinued Operations and Assets Held for Sale (Income from Discontinued Operations) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues and other income									$ 69,032	$ 111,865	$ 86,589
Cost of revenues (excludes items below)									65,733	99,228	77,047
Depreciation and amortization									3,375	3,225	2,170
Selling, general and administrative expenses									2,710	3,192	2,276
Other taxes									668	561	406
Total costs and expenses									81,279	107,403	81,899
Income from operations	$ 390	$ (1,057)	$ 575	$ (12,155)	$ 558	$ 1,680	$ 1,698	$ 526	(12,247)	4,462	4,690
Net interest and other financial costs									1,365	1,229	993
Income from discontinued operations, net of tax									1,205	806	673
Speedway | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues and other income									19,920	26,793	22,051
Cost of revenues (excludes items below)									17,573	24,860	20,557
Depreciation and amortization									244	413	320
Selling, general and administrative expenses									323	216	142
Other taxes									193	190	151
Total costs and expenses									18,333	25,679	21,170
Income from operations									1,587	1,114	881
Net interest and other financial costs									20	18	10
Income before income taxes									1,567	1,096	871
Provision for income taxes									362	290	198
Income from discontinued operations, net of tax									$ 1,205	$ 806	$ 673

Discontinued Operations and A_5

Discontinued Operations and Assets Held for Sale (Assets and Liabilities Held for Sale) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents	[1]	$ 415	$ 1,393
Receivables		5,760	7,233
Inventories		7,999	9,804
Other current assets		2,724	893
Equity method investments		5,422	6,568
Property, plant and equipment, net		39,035	40,870
Goodwill		8,256	15,650	$ 15,834
Right of use assets		1,521	1,806
Other noncurrent assets		2,637	3,204
Total assets classified as held for sale		85,158	98,556
Accounts payable		7,803	11,222
Payroll and benefits payable		732	987
Accrued taxes		1,105	1,015
Debt due within one year		2,854	704
Operating lease liabilities		497	514
Other current liabilities		822	758
Long-term debt		28,730	28,020
Defined benefit postretirement plan obligations		2,121	1,617
Long-term operating lease liabilities		1,014	1,300
Deferred credits and other liabilities		1,207	1,172
Total liabilities classified as held for sale		54,938	55,449
Speedway | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash equivalents		140	134
Receivables		217	246
Inventories		438	439
Other current assets		34	28
Equity method investments		311	330
Property, plant and equipment, net		4,784	4,745
Goodwill		4,390	4,390
Right of use assets		719	653
Other noncurrent assets		168	170
Total assets classified as held for sale		11,201	11,135
Accounts payable		300	401
Payroll and benefits payable		168	139
Accrued taxes		178	171
Debt due within one year		8	7
Operating lease liabilities		94	90
Other current liabilities		170	139
Long-term debt		122	107
Defined benefit postretirement plan obligations		25	26
Long-term operating lease liabilities		598	575
Deferred credits and other liabilities		86	93
Total liabilities classified as held for sale		$ 1,749	$ 1,748
[1]	Excludes $140 million and $134 million of cash included in assets held for sale representing Speedway store cash.

Discontinued Operations and A_6

Discontinued Operations and Assets Held for Sale (Purchase of Speedway's Interest in PFJ Southeast) (Details)	Dec. 31, 2020
Speedway | Discontinued Operations, Held-for-sale | PFJ Southeast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investments, ownership percentage	29.00%

Master Limited Partnership (Det

Master Limited Partnership (Details)	Dec. 31, 2020
MPC | MPLX
Noncontrolling Interest [Line Items]
MPC's partnership interest in MLPs (in percentage)	62.00%

Master Limited Partnership (Uni

Master Limited Partnership (Unit Repurchase Program) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Average cost per share		$ 0	$ 58.87	$ 69.46
Stock repurchase plan remaining authorized amount		$ 2,960
MPLX
Noncontrolling Interest [Line Items]
Stock repurchase program, authorized amount		$ 1,000
Stock repurchased and retired during period, shares		1,473,843
Average cost per share		$ 22.29
Stock repurchased and retired during period, value		$ 33
Stock repurchase plan remaining authorized amount		$ 967
MPLX | Subsequent Event
Noncontrolling Interest [Line Items]
Stock repurchased and retired during period, shares	99,406
Stock repurchased and retired during period, value	$ 2

Master Limited Partnership (Red

Master Limited Partnership (Redemption of Business from MPLX) (Details) - MPLX $ in Millions	Jul. 31, 2020USD ($)shares
Noncontrolling Interest [Line Items]
Partners' capital account, units, redeemed | shares	18,582,088
Partners' capital account, redemptions | $	$ 340

Master Limited Partnership (MPL

Master Limited Partnership (MPLX's Acquisition of ANDX) (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Equity transactions of MPLX & ANDX		$ (46)	$ (590)	$ (570)
Additional Paid-in Capital
Noncontrolling Interest [Line Items]
Equity transactions of MPLX & ANDX	$ (55)	(41)	(684)	2,357
Deferred income tax impact from changes in equity	$ 642	$ 14	$ 633	$ 571
Preferred Partner | Preferred Class B
Noncontrolling Interest [Line Items]
Distributions declared, per unit	$ 68.75
ANDX
Noncontrolling Interest [Line Items]
Preferred units, outstanding	600,000
MPLX | Series B Preferred Stock
Noncontrolling Interest [Line Items]
Preferred units, outstanding	600,000
Public
Noncontrolling Interest [Line Items]
Common units conversion ratio - ANDX to MPLX	1.135
MPC
Noncontrolling Interest [Line Items]
Common units conversion ratio - ANDX to MPLX	1.0328

Master Limited Partnership (M_2

Master Limited Partnership (MPLX-Dropdowns to MPLX and GP/IDR Exchange) (Details) - MPLX shares in Millions, $ in Billions	Feb. 01, 2018USD ($)shares
Limited Partner
Noncontrolling Interest [Line Items]
Units issued, number of units	112
Conversion of stock, shares issued	275
General Partner
Noncontrolling Interest [Line Items]
Units issued, number of units	2
MPLX 364-day term loan
Noncontrolling Interest [Line Items]
Line of credit facility, maximum borrowing capacity | $	$ 4.1
Debt instrument, term	364 days
Cash and cash equivalents
Noncontrolling Interest [Line Items]
Cash payment for acquisition | $	$ 4.1

Master Limited Partnership (Non

Master Limited Partnership (Noncontrolling Interest) (Details) - USD ($) $ in Millions	Jul. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (decrease) in MPC's additional paid-in capital, net of tax		$ (46)	$ (590)	$ (570)
Additional Paid-in Capital
Increase due to the issuance of MPLX common units and general partner units to MPC		0	0	1,114
Increase due to GP/IDR Exchange		0	0	1,808
Increase (decrease) due to the issuance of MPLX & ANDX common units		(27)	(51)	6
Tax impact	$ (642)	(14)	(633)	(571)
Increase (decrease) in MPC's additional paid-in capital, net of tax	$ (55)	$ (41)	$ (684)	$ 2,357

Impairments (Income Statement L

Impairments (Income Statement Location of Impairments) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020		Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss	$ 7,330	$ 7,394	[1]	$ 1,197	[1]
Equity method investment, other than temporary impairment	$ 1,315
Impairment charges		9,741		1,239
Impairment expense
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss		7,394		1,197
Impairment of long-lived assets held-for-use		1,032	[2]	0
Income (loss) from equity method investments
Finite-Lived Intangible Assets [Line Items]
Equity method investment, other than temporary impairment		$ 1,315		$ 42
[1]	See Note 7.
[2]	The remaining difference not described in the narrative below is related to certain immaterial Midstream assets.

Impairments (Goodwill) (Details

Impairments (Goodwill) (Details) - USD ($) $ in Millions		3 Months Ended			12 Months Ended
		Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2020		Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss			$ 7,330		$ 7,394	[1]	$ 1,197	[1]
Transfers					0
Discounted Cash Flow Approach | Discount Rate | Minimum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs			9.00%
Discounted Cash Flow Approach | Discount Rate | Maximum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs			13.50%
Income Approach | Discount Rate | Minimum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs				9.00%
Income Approach | Discount Rate | Maximum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs				10.00%
Refining & Marketing
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss		$ 64			5,580	[1]	0	[2]
Transfers					8
Midstream
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss	[1]				1,814		$ 1,197
Transfers					$ (8)
Midstream | Prior to change in reporting units
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss				$ 1,156
Midstream | Subsequent to change in reporting units
Finite-Lived Intangible Assets [Line Items]
Goodwill, impairment loss				$ 41
MPLX Wholesale Distribution Business
Finite-Lived Intangible Assets [Line Items]
Transfers		$ 64
[1]	See Note 7.
[2]	Recast to include the direct dealer business. See Note 13 for additional information.

Impairments (Equity Method Inve

Impairments (Equity Method Investments) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Equity method investment, other than temporary impairment	$ 1,315
MPLX | Equity method investments
Finite-Lived Intangible Assets [Line Items]
Income (loss) from equity method investments from asset impairment and elimination of basis differential		$ 28
MPLX | Equity method investment - basis difference
Finite-Lived Intangible Assets [Line Items]
Income (loss) from equity method investments from asset impairment and elimination of basis differential		$ 14
MPLX | MarkWest Utica EMG
Finite-Lived Intangible Assets [Line Items]
Equity method investment, other than temporary impairment	$ 1,250

Impairments (Long-Lived Assets)

Impairments (Long-Lived Assets) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	[1]	Dec. 31, 2019	Jun. 30, 2020
Impairment expense
Finite-Lived Intangible Assets [Line Items]
Impairment of long-lived assets held-for-use				$ 1,032		$ 0
Minimum
Finite-Lived Intangible Assets [Line Items]
Reporting unit, percentage of fair value in excess of carrying amount							17.00%
Refining & Marketing | Impairment expense
Finite-Lived Intangible Assets [Line Items]
Impairment of long-lived assets held-for-use	$ 44	$ 342	$ 142
Midstream | Impairment expense | MPLX
Finite-Lived Intangible Assets [Line Items]
Impairment of long-lived assets held-for-use	$ 67	$ 27	$ 350
[1]	The remaining difference not described in the narrative below is related to certain immaterial Midstream assets.

Acquisitions (Acquisition of An

Acquisitions (Acquisition of Andeavor) (Details) - USD ($) $ / shares in Units, $ in Millions		Oct. 01, 2018	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2018		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Business Acquisition [Line Items]
Fair value of converted equity awards							$ 0		$ 0		$ 203
Goodwill					$ 15,834		8,256		15,650		15,834
Goodwill, impairment loss				$ 7,330			7,394	[1]	1,197	[1]
Refining & Marketing
Business Acquisition [Line Items]
Goodwill					5,511	[2]	561		6,133	[2]	5,511	[2]
Goodwill, impairment loss			$ 64				5,580	[1]	0	[2]
Midstream
Business Acquisition [Line Items]
Goodwill					10,323		7,695		9,517		$ 10,323
Goodwill, impairment loss	[1]						$ 1,814		$ 1,197
Andeavor
Business Acquisition [Line Items]
Common units conversion ratio		1.87
Cash consideration to unitholders (per unit)		$ 152.27
Common shares converted to cash, number of shares		22,900,000
Shares converted, number of shares		128,200,000
Shares issued or issuable, number of shares		239,800,000
Cash payment for acquisition		$ 3,486
Fair value of converted equity awards		203
Goodwill		17,300
Goodwill, expected tax deductible amount		1,000
Transaction costs		47
Sales and other operating revenues					$ 11,300
Pro-forma, purchase accounting inventory effects and transaction-related costs effect on net income attributable to MPC		727
Andeavor | Refining & Marketing
Business Acquisition [Line Items]
Goodwill		5,200
Andeavor | Midstream
Business Acquisition [Line Items]
Goodwill		8,100
Andeavor | Retail
Business Acquisition [Line Items]
Goodwill		$ 3,900
[1]	See Note 7.
[2]	Recast to include the direct dealer business. See Note 13 for additional information.

Acquisitions (Fair Value of Con

Acquisitions (Fair Value of Consideration Transferred - Andeavor) (Details) - USD ($) $ in Millions	Oct. 01, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Fair value of MPC shares issued		$ 0	$ 0	$ 19,766
Fair value of converted equity awards		$ 0	$ 0	$ 203
Andeavor
Business Acquisition [Line Items]
Fair value of MPC shares issued	$ 19,766
Cash payment to Andeavor stockholders	3,486
Cash settlement of non-employee director units	7
Fair value of converted equity awards	203
Total fair value of consideration transferred	$ 23,462

Acquisitions (Pro Forma Financi

Acquisitions (Pro Forma Financial Information - Andeavor) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Sales and other operating revenues	$ 17,972	$ 17,408	$ 12,195	$ 22,204	$ 28,008	$ 27,552	$ 30,239	$ 25,349	$ 69,779	$ 111,148	$ 86,086
Net income attributable to MPC	$ 285	$ (886)	$ 9	$ (9,234)	$ 443	$ 1,095	$ 1,106	$ (7)	$ (9,826)	$ 2,637	2,780
Andeavor
Business Acquisition [Line Items]
Sales and other operating revenues											131,921
Net income attributable to MPC											$ 4,218

Acquisitions (Acquisition of Te

Acquisitions (Acquisition of Terminal and Retail Locations in New York) (Details) $ in Millions	Jul. 12, 2019USD ($)bblStore	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Goodwill		$ 8,256	$ 15,650	$ 15,834
NOCO
Business Acquisition [Line Items]
Barrels handled | bbl	900,000
Number of stores | Store	33
Cash payment for acquisition	$ 135
Property, plant and equipment, net	38
Inventories	3
Goodwill	$ 94

Acquisitions (Acquisition of Ex

Acquisitions (Acquisition of Express Mart) (Details) $ in Millions	Nov. 16, 2018USD ($)Store	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Goodwill		$ 8,256	$ 15,650	$ 15,834
Express Mart
Business Acquisition [Line Items]
Number of stores | Store	78
Cash payment for acquisition	$ 266
Property, plant and equipment, net	97
Inventories	9
Finite-lived intangibles	2
Goodwill	$ 158

Acquisitions (Acquisition of Mt

Acquisitions (Acquisition of Mt. Airy Terminal) (Details) bbl / d in Thousands, bbl in Millions, $ in Millions	Sep. 26, 2018USD ($)bbl / dbbl	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Goodwill		$ 8,256	$ 15,650	$ 15,834
Mt. Airy Terminal
Business Acquisition [Line Items]
Storage capacity | bbl	4
Barrels handled | bbl / d	120
Mt. Airy Terminal | MPLX
Business Acquisition [Line Items]
Cash payment for acquisition	$ 446
Property, plant and equipment, net	336
Goodwill	121
Mt. Airy Terminal | MPLX | Previously Reported
Business Acquisition [Line Items]
Cash payment for acquisition	451
Mt. Airy Terminal | MPLX | Restatement Adjustment
Business Acquisition [Line Items]
Cash payment for acquisition	$ 5

Variable Interest Entities (Bal

Variable Interest Entities (Balance Sheet Information for Consolidated VIEs) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	[1]	$ 415	$ 1,393
Receivables		5,760	7,233
Inventories		7,999	9,804
Other current assets		2,724	893
Assets held for sale		11,389	11,135
Equity method investments		5,422	6,568
Property, plant and equipment, net		39,035	40,870
Goodwill		8,256	15,650	$ 15,834
Right of use assets		1,521	1,806
Other noncurrent assets		2,637	3,204
Liabilities
Accounts payable		7,803	11,222
Payroll and benefits payable		732	987
Accrued taxes		1,105	1,015
Debt due within one year		2,854	704
Operating lease liabilities		497	514
Liabilities held for sale		1,850	1,748
Other current liabilities		822	758
Long-term debt		28,730	28,020
Deferred income taxes		6,203	6,392
Long-term operating lease liabilities		1,014	1,300
Deferred credits and other liabilities		1,207	1,172
VIE, Primary Beneficiary | MPLX
Assets
Cash and cash equivalents		15	15
Receivables		478	615
Inventories		118	110
Other current assets		67	110
Assets held for sale		188	0
Equity method investments		4,036	5,275
Property, plant and equipment, net		21,418	22,174
Goodwill		7,657	9,536
Right of use assets		309	365
Other noncurrent assets		1,006	1,323
Liabilities
Accounts payable		468	744
Payroll and benefits payable		4	5
Accrued taxes		76	80
Debt due within one year		764	9
Operating lease liabilities		63	66
Liabilities held for sale		101	0
Other current liabilities		297	259
Long-term debt		19,375	19,704
Deferred income taxes		12	12
Long-term operating lease liabilities		244	302
Deferred credits and other liabilities		$ 437	$ 409
[1]	Excludes $140 million and $134 million of cash included in assets held for sale representing Speedway store cash.

Variable Interest Entities (Non

Variable Interest Entities (Non-Consolidated VIEs) (Details) $ in Millions	Dec. 31, 2020USD ($)
Crowley Coastal Partners, LLC
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure, amount	$ 424

Related Party Transactions (Rel

Related Party Transactions (Related Party Transactions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transactions [Abstract]
Sales to related parties	$ 123	$ 91	$ 14
Purchases from related parties	$ 738	$ 763	$ 610

Earnings per Share (Summary Of

Earnings per Share (Summary Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Income (loss) from continuing operations, net of tax	$ 250		$ (980)		$ 84		$ (10,536)		$ 77		$ 1,113		$ 1,109		$ 150		$ (11,182)	$ 2,449	$ 2,933
Net income attributable to noncontrolling interest																	(151)	618	826
Net income allocated to participating securities																	1	1	1
Income (loss) from continuing operations available to common stockholders																	(11,032)	1,830	2,106
Income from discontinued operations, net of tax																	1,205	806	673
Income (loss) available to common stockholders																	$ (9,827)	$ 2,636	$ 2,779
Weighted average common shares outstanding:
Basic (in shares)																	649	659	518
Effect of dilutive securities (in shares)																	0	5	8
Diluted (in shares)																	649	664	526
Basic:
Continuing operations	$ (0.06)	[1]	$ (1.93)	[1]	$ (0.28)	[1]	$ (14.74)	[1]	$ 0.40	[1]	$ 1.28	[1]	$ 1.28	[1]	$ (0.17)	[1]	$ (16.99)	$ 2.78	$ 4.06
Discontinued operations																	1.86	1.22	1.30
Net income (loss) per share																	(15.13)	4	5.36
Diluted:
Continuing operations	$ (0.06)	[1]	$ (1.93)	[1]	$ (0.28)	[1]	$ (14.74)	[1]	$ 0.40	[1]	$ 1.27	[1]	$ 1.27	[1]	$ (0.17)	[1]	(16.99)	2.76	4
Discontinued operations																	1.86	1.21	1.28
Net income (loss) per share																	$ (15.13)	$ 3.97	$ 5.28
[1]	The sum of the per-share amounts for the four quarters may not always equal the annual per-share amounts due to differences in the average number of shares outstanding during the respective periods.

Earnings per Share (Anti-diluti

Earnings per Share (Anti-dilutive Shares) (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares issuable under stock-based compensation plans
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	11	3	0

Equity (Narrative) (Details)

Equity (Narrative) (Details) $ in Millions	Dec. 31, 2020USD ($)
Equity [Abstract]
Stock repurchase plan remaining authorized amount	$ 2,960

Equity (Share Repurchases) (Det

Equity (Share Repurchases) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Number of shares repurchased	0	34	47
Common stock repurchased	$ 0	$ 1,950	$ 3,287
Average cost per share	$ 0	$ 58.87	$ 69.46

Segment Information (Narrative)

Segment Information (Narrative) (Details) $ in Billions	12 Months Ended
	Dec. 31, 2020Segment	Dec. 31, 2019	Dec. 31, 2018	Aug. 02, 2020USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	2
Speedway
Segment Reporting Information [Line Items]
Percent of annual revenues	11.00%	12.00%	13.00%
Speedway | Discontinued Operations, Disposed of by Sale
Segment Reporting Information [Line Items]
Consideration | $				$ 21

Segment Information (Income Fro

Segment Information (Income From Operations Attributable To Operating Segments) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Sales and other operating revenues		$ 17,972	$ 17,408	$ 12,195	$ 22,204	$ 28,008	$ 27,552	$ 30,239	$ 25,349	$ 69,779		$ 111,148	$ 86,086
Income from operations		$ 390	$ (1,057)	$ 575	$ (12,155)	$ 558	$ 1,680	$ 1,698	$ 526	(12,247)		4,462	4,690
Depreciation and amortization										3,375		3,225	2,170
Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues										66,180		107,305	82,755
Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues										3,599		3,843	3,331
Reportable Segment [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	[1]									69,779		111,148	86,086
Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues										4,906		5,020	3,395
Intersegment Eliminations | Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues										67		103	66
Intersegment Eliminations | Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues										4,839		4,917	3,329
Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues										74,685		116,168	89,481
Income from operations										(1,481)		6,450	5,406
Depreciation and amortization										3,210	[2]	3,047	2,092	[2]
Segment capital expenditures and investments	[3]									2,568		5,335	3,707
Operating Segments | Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues										66,247		107,408	82,821
Income from operations										(5,189)		2,856	2,654
Depreciation and amortization										1,857		1,780	1,207
Segment capital expenditures and investments										1,170		2,045	1,077
Operating Segments | Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues										8,438		8,760	6,660
Income from operations										3,708		3,594	2,752
Depreciation and amortization										1,353		1,267	885
Segment capital expenditures and investments										$ 1,398		$ 3,290	$ 2,630
[1]	Includes Refining & Marketing sales to Speedway (as discussed above) and related party sales. See Note 10 for additional information.
[2]	Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other items not allocated to segments.
[3]	Includes changes in capital expenditure accruals and investments in affiliates.

Segment Information (Reconcilia

Segment Information (Reconciliation Of Segment Income From Operations To Income Before Income Taxes) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		$ 390	$ (1,057)	$ 575	$ (12,155)	$ 558	$ 1,680	$ 1,698	$ 526	$ (12,247)		$ 4,462		$ 4,690
Restructuring expenses										367		0		0
Net interest and other financial costs										1,365		1,229		993
Income (loss) from continuing operations before income taxes										(13,612)		3,233		3,697
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations										(1,481)		6,450		5,406
Corporate
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations	[1]									(800)		(833)		(528)
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Impairments										(9,741)	[2]	(1,239)		9	[2]
Restructuring expenses										(367)	[3]	0		0
Litigation										84		(22)		0
Gain on sale of assets										66		0		0
Transaction-related costs	[4]									(8)		(153)		(197)
Equity method investment restructuring gains										$ 0		$ 259	[5]	$ 0
[1]	Corporate consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. Corporate includes corporate costs of $26 million, $28 million and $26 million for 2020, 2019 and 2018, respectively, that are no longer allocable to Speedway under discontinued operations accounting.
[2]	2020 reflects impairments of goodwill, equity method investments and long lived assets. 2019 reflects impairments of goodwill and equity method investments. See Note 7. 2018 includes MPC’s share of gains from the sale of assets remaining from the Sandpiper pipeline project, which was cancelled and impaired in 2016.
[3]	See Note 4.
[4]	2020 and 2019 includes costs incurred in connection with the Midstream strategic review and other related efforts. Both 2019 and 2018 include employee severance, retention and other costs related to the acquisition of Andeavor. Effective October 1, 2019, we have discontinued reporting Andeavor transaction-related costs as one year has passed since the acquisition and these costs are immaterial. Costs incurred in connection with the Speedway separation are included in discontinued operations. See Note 5
[5]	(e) Includes gains related to The Andersons Marathon Holdings LLC and Capline Pipeline Company LLC. See Note 17.

Segment Information (Reconcil_2

Segment Information (Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Plus items not allocated to segments:
Total capital expenditures	[1]	$ 2,269	$ 4,508	$ 3,455
Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Segment capital expenditures and investments	[2]	2,568	5,335	3,707
Investments in equity method investments		485	1,064	409
Corporate
Plus items not allocated to segments:
Corporate		80	100	77
Capitalized interest		$ 106	$ 137	$ 80
[1]	Includes changes in capital expenditure accruals. See Note 24 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows
[2]	Includes changes in capital expenditure accruals and investments in affiliates.

Net Interest and Other Financ_3

Net Interest and Other Financial Costs (Net Interest and Other Financial Costs) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Interest income		$ (9)	$ (40)	$ (87)
Interest expense		1,462	1,389	1,025
Interest capitalized		(129)	(158)	(80)
Pension and other postretirement non-service costs	[1]	11	4	53
(Gain) loss on extinguishment of debt		(9)	0	64
Other financial costs		39	34	18
Net interest and other financial costs		$ 1,365	$ 1,229	$ 993
[1]	See Note 26.

Income Taxes (Income Taxes Narr

Income Taxes (Income Taxes Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 11	$ 11
Unrecognized tax benefits that would impact effective income tax rate	14
Uncertain tax positions, reasonably possible increase or decrease during the next twelve months	9
Statute of limitations	0	160	$ 12
Unrecognized tax benefits income tax net penalties and interest expense (benefits)	(19)	(2)	$ 1
Interest and penalties accrued	(5)	7
Andeavor
Operating Loss Carryforwards [Line Items]
Statute of limitations		159
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Valuation allowance	2	2
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 4	7
Domestic Tax Authority | Minimum
Operating Loss Carryforwards [Line Items]
Tax years	2016
Domestic Tax Authority | Maximum
Operating Loss Carryforwards [Line Items]
Tax years	2019
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 228	11
Valuation allowance	$ 9	$ 9
State and Local Jurisdiction | Minimum
Operating Loss Carryforwards [Line Items]
Tax years	2006
State and Local Jurisdiction | Maximum
Operating Loss Carryforwards [Line Items]
Tax years	2019
CARES Act
Operating Loss Carryforwards [Line Items]
Income taxes receivable, current	$ 2,100

Income Taxes (Components Of Inc

Income Taxes (Components Of Income Tax Provisions (Benefits)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ (2,267)	$ (52)	$ 674
State and local	69	28	54
Foreign	9	1	22
Total current	(2,189)	(23)	750
Deferred:
Federal	90	742	(119)
State and local	(347)	56	149
Foreign	16	9	(16)
Total deferred	(241)	807	14
Income tax provision (benefit)	$ (2,430)	$ 784	$ 764

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Federal Statutory Income Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%	21.00%
State and local income taxes, net of federal income tax effects	2.00%	2.00%	5.00%
Goodwill impairment	(8.00%)	5.00%	0.00%
Noncontrolling interests	0.00%	(4.00%)	(5.00%)
Legislation	4.00%	0.00%	0.00%
Other	(1.00%)	0.00%	0.00%
Effective tax rate applied to income (loss) from continuing operations before income taxes	18.00%	24.00%	21.00%

Income Taxes (Components Of Def

Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Employee benefits	$ 647	$ 693
Environmental remediation	95	99
Finance lease obligations	103	105
Debt financing	6	17
Operating lease liabilities	453	498
Net operating loss carryforwards	232	18
Foreign currency	0	15
Tax credit carryforwards	19	14
Other	74	57
Total deferred tax assets	1,629	1,516
Deferred tax liabilities:
Property, plant and equipment	3,195	3,301
Inventories	800	652
Investments in subsidiaries and affiliates	3,331	3,114
Goodwill and other intangibles	34	304
Right of use assets	451	498
Other	18	19
Total deferred tax liabilities	7,829	7,888
Net deferred tax liabilities	$ 6,200	$ 6,372

Income Taxes (Components Of Net

Income Taxes (Components Of Net Deferred Tax Liabilities Classified In Consolidated Balance Sheets) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Net deferred tax liabilities		$ 6,200	$ 6,372
Other noncurrent assets
Net deferred tax liabilities		3	20
Other Noncurrent Liabilities [Member]
Net deferred tax liabilities	[1]	$ 6,203	$ 6,392
[1]	The deferred income tax assets and liabilities associated with discontinued operations remain in our balance sheet rather than being included in the carrying amount of assets and liabilities that are held for sale, as the sale is structured as a sale of assets. These discontinued operations deferred income tax assets and liabilities will be realized upon the sale of Speedway.

Income Taxes (Summary Of Activi

Income Taxes (Summary Of Activity In Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
January 1 balance	$ 32	$ 211	$ 19
Additions for tax positions of prior years	12	2	0
Reductions for tax positions of prior years	(18)	(2)	(5)
Settlements, decrease	(3)	(19)	0
Statute of limitations	0	160	12
Acquired from Andeavor	0	0	209
December 31 balance	$ 23	$ 32	$ 211

Inventories (Summary Of Invento

Inventories (Summary Of Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Crude oil	$ 2,588	$ 3,472
Refined products	4,478	5,359
Materials and supplies	933	973
Total	$ 7,999	$ 9,804

Inventories (Narrative) (Detail

Inventories (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Total inventory LIFO percentage	88.00%	90.00%
Excess of current acquisition costs over stated LIFO value	$ 0	$ 787
Effect of LIFO inventory liquidation on income	$ 561	$ 0	$ 0

Equity Method Investments (The

Equity Method Investments (The Andersons Marathon Holdings LLC) (Details) - USD ($) $ in Millions		Oct. 01, 2019	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Contribution of net assets	[1]		$ 0	$ 266		$ 0
Fair value of asset acquired			$ 0	$ 525	[2]	$ 0
The Andersons Marathon Holdings LLC
Schedule of Equity Method Investments [Line Items]
Contribution of net assets		$ 123
Fair value of asset acquired		175
Non-cash gain on exchange of equity ownership interests		$ 52
[1]	2019 includes the contribution of net assets to TAMH and Capline LLC. See Note 17.
[2]	2019 includes the recognition of TAMH and Capline LLC equity method investments. See Note 17.

Equity Method Investments (Capl

Equity Method Investments (Capline LLC) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Contribution of net assets	[1]		$ 0	$ 266		$ 0
Fair value of asset acquired			$ 0	$ 525	[2]	$ 0
Capline LLC
Schedule of Equity Method Investments [Line Items]
Undivided joint interest, ownership percentage		33.00%
Equity method investments, ownership percentage		33.00%
Contribution of net assets		$ 143
Fair value of asset acquired		350
Equity method investment restructuring gains		$ 207
[1]	2019 includes the contribution of net assets to TAMH and Capline LLC. See Note 17.
[2]	2019 includes the recognition of TAMH and Capline LLC equity method investments. See Note 17.

Equity Method Investments (Sche

Equity Method Investments (Schedule Of Equity Method Investments) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 5,422	$ 6,568
The Andersons Marathon Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%
Watson Cogeneration Company
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		51.00%
Capline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage				33.00%
MPLX | Andeavor Logistics Rio Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		67.00%
MPLX | Centrahoma Processing LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		40.00%
MPLX | Explorer Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		25.00%
MPLX | Illinois Extension Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		35.00%
MPLX | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		41.00%
MPLX | MarEn Bakken Company LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		25.00%
MPLX | MarkWest EMG Jefferson Dry Gas
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		67.00%
MPLX | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		57.00%
MPLX | Minnesota Pipe Line Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		17.00%
MPLX | Rendezvous Gas Services, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		78.00%
MPLX | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		51.00%
MPLX | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%
MPLX | Whistler Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		38.00%
MPLX | Wink to Webster Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		0.00%
MPLX | W2W Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%
Marathon Petroleum Corporation | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		10.00%
Marathon Petroleum Corporation | Capline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		33.00%
Marathon Petroleum Corporation | Crowley Coastal Partners, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%
Marathon Petroleum Corporation | Gray Oak Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		25.00%
Marathon Petroleum Corporation | South Texas Gateway Terminal LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		25.00%
Refining & Marketing
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 184	203
Refining & Marketing | The Andersons Marathon Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		159	177
Refining & Marketing | Watson Cogeneration Company
Schedule of Equity Method Investments [Line Items]
Equity method investments		25	26
Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments		5,238	6,365
Midstream | MPLX
Schedule of Equity Method Investments [Line Items]
Equity method investments		4,036	5,275
Midstream | MPLX | Andeavor Logistics Rio Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments		194	202
Midstream | MPLX | Centrahoma Processing LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		145	153
Midstream | MPLX | Explorer Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments		72	83
Midstream | MPLX | Illinois Extension Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments		254	265
Midstream | MPLX | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		252	238
Midstream | MPLX | MarEn Bakken Company LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		465	481
Midstream | MPLX | MarkWest EMG Jefferson Dry Gas
Schedule of Equity Method Investments [Line Items]
Equity method investments		307	302
Midstream | MPLX | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments		698	1,984
Midstream | MPLX | Minnesota Pipe Line Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		188	190
Midstream | MPLX | Rendezvous Gas Services, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investments		159	170
Midstream | MPLX | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments		148	157
Midstream | MPLX | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments		557	537
Midstream | MPLX | Whistler Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		185	134
Midstream | MPLX | Wink to Webster Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	0	126
Midstream | MPLX | W2W Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	72	0
Midstream | MPLX | Other equity method investees
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	340	253
Midstream | Marathon Petroleum Corporation
Schedule of Equity Method Investments [Line Items]
Equity method investments		1,202	1,090
Midstream | Marathon Petroleum Corporation | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		63	59
Midstream | Marathon Petroleum Corporation | Capline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		390	374
Midstream | Marathon Petroleum Corporation | Crowley Coastal Partners, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		190	188
Midstream | Marathon Petroleum Corporation | Gray Oak Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		342	298
Midstream | Marathon Petroleum Corporation | South Texas Gateway Terminal LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments		168	85
Midstream | Marathon Petroleum Corporation | Other equity method investees
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	$ 49	$ 86
[1]	During 2020, MPLX contributed its ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC. (b) Some investments included within “Other” have been deemed to be VIEs.
[2]	Some investments included within “Other” have been deemed to be VIEs

Equity Method Investments (Summ

Equity Method Investments (Summarized Financial Information For Equity Method Investees) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income statement data:
Revenues and other income									$ 69,032	$ 111,865	$ 86,589
Income from operations	$ 390	$ (1,057)	$ 575	$ (12,155)	$ 558	$ 1,680	$ 1,698	$ 526	(12,247)	4,462	4,690
Net income	574	$ (609)	$ 276	$ (10,218)	262	$ 1,367	$ 1,367	$ 259	(9,977)	3,255	3,606
Balance sheet data – December 31:
Current assets	28,287				30,458				28,287	30,458
Current liabilities	15,663				16,948				15,663	16,948
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Income statement data:
Revenues and other income									3,013	3,282	3,092
Income from operations									599	1,176	1,105
Net income									454	987	$ 972
Balance sheet data – December 31:
Current assets	1,298				1,195				1,298	1,195
Noncurrent assets	17,697				16,362				17,697	16,362
Current liabilities	754				997				754	997
Noncurrent liabilities	$ 4,736				$ 2,769				$ 4,736	$ 2,769

Equity Method Investments (Narr

Equity Method Investments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment difference between carrying amount and underlying equity	$ 361
Equity method investment difference between carrying amount and underlying equity portion related to goodwill and other assets not amortized	199
Distributions from equity method investments	$ 577	$ 569	$ 458

Property, Plant and Equipment_2

Property, Plant and Equipment (Summary Of Property, Plant And Equipment) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 59,339		$ 57,586
Accumulated depreciation		20,304	[1]	16,716
Net property, plant and equipment		39,035		40,870
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment	[2]	30,306		29,101
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment		27,677		27,193
Corporate
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 1,356		$ 1,292
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		1 year
Minimum | Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		4 years
Minimum | Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		1 year
Minimum | Corporate
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		4 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		61 years
Maximum | Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		30 years
Maximum | Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		61 years
Maximum | Corporate
Property, Plant and Equipment [Line Items]
Estimated useful lives (in years)		40 years
[1]	The December 31, 2020 balance includes property, plant and equipment impairment charges recorded during 2020. See Note 7 for additional information.
[2]	Recast to include the direct dealer business. See Note 13 for additional information.

Property, Plant and Equipment_3

Property, Plant and Equipment (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Finance leases, gross	$ 819	$ 740
Finance leases, accumulated depreciation	272	215
Property, plant and equipment	59,339	57,586
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,830	$ 3,120

(Changes In Carrying Amount Of

(Changes In Carrying Amount Of Goodwill) (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2020		Dec. 31, 2019
Goodwill [Line Items]
Beginning balance			$ 15,650	$ 15,650		$ 15,834
Acquisitions						38
Purchase price allocation adjustments						992
Impairments			(7,330)	(7,394)	[1]	(1,197)	[1]
Dispositions						(17)
Transfers				0
Ending balance				8,256		15,650
Refining & Marketing
Goodwill [Line Items]
Beginning balance	[2]		6,133	6,133		5,511
Acquisitions	[2]					38
Purchase price allocation adjustments	[2]					584
Impairments		$ (64)		(5,580)	[1]	0	[2]
Dispositions	[2]					0
Transfers				8
Ending balance				561		6,133	[2]
Midstream
Goodwill [Line Items]
Beginning balance			$ 9,517	9,517		10,323
Acquisitions						0
Purchase price allocation adjustments						408
Impairments	[1]			(1,814)		(1,197)
Dispositions						(17)
Transfers				(8)
Ending balance				$ 7,695		$ 9,517
[1]	See Note 7.
[2]	Recast to include the direct dealer business. See Note 13 for additional information.

Goodwill and Intangibles (Intan

Goodwill and Intangibles (Intangible Assets by Major Class) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	$ 3,628	$ 3,540
Accumulated amortization	1,268	734
Net	2,360	2,806
Customer contracts and relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	3,359	3,271
Accumulated amortization	1,119	612
Net	2,240	2,659
Brand rights and tradenames
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	100	100
Accumulated amortization	35	20
Net	65	80
Royalty agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	133	133
Accumulated amortization	87	78
Net	46	55
Other intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	36	36
Accumulated amortization	27	24
Net	$ 9	$ 12

Goodwill and Intangibles (Int_2

Goodwill and Intangibles (Intangibles Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Indefinite-lived intangible assets	$ 71	$ 71
Amortization expense	$ 336	$ 357

Goodwill and Intangibles (Estim

Goodwill and Intangibles (Estimated Future Amortization Expense) (Details) $ in Millions	Dec. 31, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 347
2022	346
2023	330
2024	277
2025	$ 257

Fair Value Measurements (Assets

Fair Value Measurements (Assets And Liabilities Accounted For At Fair Value On Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash collateral netted with derivative liabilities		$ 11	$ 51
Fair Value, Measurements, Recurring | Commodity derivative instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - collateral and netting	[1]	(80)	(55)
Commodity derivative instruments, assets - net	[2]	8	8
Commodity derivative instruments, assets - collateral pledged not offset		31	73
Commodity derivative instruments, liabilities - netting and collateral	[1]	(91)	(106)
Commodity derivative instruments, liabilities, net	[2]	0	0
Commodity derivative instruments, liabilities - collateral pledged not offset		0	0
Fair Value, Measurements, Recurring | Commodity derivative instruments | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - gross		82	57
Commodity derivative instruments, liabilities - gross		81	95
Fair Value, Measurements, Recurring | Commodity derivative instruments | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - gross		6	6
Commodity derivative instruments, liabilities - gross		10	11
Fair Value, Measurements, Recurring | Commodity derivative instruments | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - gross		0	0
Commodity derivative instruments, liabilities - gross		0	0
Fair Value, Measurements, Recurring | Embedded derivative in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - netting and collateral		0	0
Commodity derivative instruments, liabilities, net		63	60
Commodity derivative instruments, liabilities - collateral pledged not offset		0	0
Fair Value, Measurements, Recurring | Embedded derivative in commodity contracts | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		0	0
Fair Value, Measurements, Recurring | Embedded derivative in commodity contracts | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		0	0
Fair Value, Measurements, Recurring | Embedded derivative in commodity contracts | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		$ 63	$ 60
[1]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of December 31, 2020, cash collateral of $11 million was netted with mark-to-market liabilities. As of December 31, 2019, cash collateral of $51 million was netted with mark-to-market derivative liabilities.
[2]	We have no derivative contracts which are subject to master netting arrangements reflected gross on the balance sheet.

Fair Value Measurements (Recurr

Fair Value Measurements (Recurring Narrative) (Details) - Level 3	12 Months Ended
	Dec. 31, 2020USD ($)$ / gal
Commodity derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, average forward price | $ / gal	0.59
Commodity derivative instruments | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, forward price	0.47
Commodity derivative instruments | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, forward price	1.09
Embedded derivative in commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Probability of renewal	100.00%
Probability of renewal second term	100.00%

Fair Value Measurements (Reconc

Fair Value Measurements (Reconciliation Of Net Beginning And Ending Balances Recorded For Net Assets And Liabilities Classified As Level 3) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 60	$ 61
Unrealized and realized losses included in net income	9	5
Settlements of derivative instruments	(6)	(6)
Ending balance	$ 63	$ 60

Fair Value Measurements (Gains_

Fair Value Measurements (Gains/Losses Included In Earnings Relating to Assets Still Held at the End of Period) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period:	$ 4	$ 5

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Values - Reported) (Details) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 31.1	$ 28.3
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 34.9	$ 30.1

Derivatives (Classification Of

Derivatives (Classification Of Gross Fair Values Of Derivative Instruments, Excluding Cash Collateral) (Details) - Commodity derivative instruments - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Other current assets
Derivatives, Fair Value [Line Items]
Asset		$ 88	$ 63
Liability		91	106
Other current liabilities
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	7	5
Deferred credits and other liabilities
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	$ 56	$ 55
[1]	Includes embedded derivatives.

Derivatives (Open Commodity Der

Derivatives (Open Commodity Derivative Contracts) (Details) - Exchange Traded gal in Thousands, bbl in Thousands	12 Months Ended
	Dec. 31, 2020bblgal
Crude oil
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	81.90%
Crude oil | Long
Derivative [Line Items]
Notional contracts (contract volumes)	17,474	[1]
Crude oil | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	11,197	[1]
Refined products
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	89.00%
Refined products | Long
Derivative [Line Items]
Notional contracts (contract volumes)	13,923	[1]
Refined products | Long | Spread contracts
Derivative [Line Items]
Notional contracts (contract volumes)	935
Refined products | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	9,354	[1]
Refined products | Short | Spread contracts
Derivative [Line Items]
Notional contracts (contract volumes)	455
Blending products
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	100.00%
Blending products | Long
Derivative [Line Items]
Notional contracts (contract volumes)	3,206	[1]
Blending products | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	3,987	[1]
Soybean oil
Derivative [Line Items]
Percentage of derivative contracts expiring next quarter	100.00%
Soybean oil | Long
Derivative [Line Items]
Notional contracts (contract volumes)	558
Soybean oil | Short
Derivative [Line Items]
Notional contracts (contract volumes) | gal	1,117
[1]	Included in exchange-traded are spread contracts in thousands of barrels: Refined products - 935 long and 455 short

Derivatives (Effect Of Commodit

Derivatives (Effect Of Commodity Derivative Instruments In Statements Of Income) (Details) - Commodity derivative instruments - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ 107	$ (96)	$ (46)
Sales and other operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	72	(19)	13
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	34	(77)	(59)
Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ 1	$ 0	$ 0

Debt (Outstanding Borrowings) (

Debt (Outstanding Borrowings) (Details) - USD ($) $ in Millions	Dec. 31, 2020		Aug. 18, 2020	Apr. 27, 2020	Dec. 31, 2019	Sep. 09, 2019
Debt Instrument [Line Items]
Finance lease obligations	$ 645				$ 593
Total debt	32,044				29,168
Unamortized debt issuance costs	(154)				(134)
Unamortized (discount) premium, net	(306)				(310)
Amounts due within one year	(2,854)				(704)
Total long-term debt due after one year	28,730				28,020
Senior Notes
Debt Instrument [Line Items]
Long-term debt outstanding				$ 2,500
Marathon Petroleum Corporation
Debt Instrument [Line Items]
Commercial paper	1,024				0
Notes payable	1				1
Marathon Petroleum Corporation | Senior Notes
Debt Instrument [Line Items]
Long-term debt outstanding	9,849				8,474
Marathon Petroleum Corporation | Finance Lease
Debt Instrument [Line Items]
Finance lease obligations	634				574
MPLX | MPLX revolving credit facility due July 2024
Debt Instrument [Line Items]
Bank revolving credit facility	175	[1]			0
MPLX | Senior Notes
Debt Instrument [Line Items]
Long-term debt outstanding	20,350		$ 3,000		19,100	$ 2,000
MPLX | Line of Credit | MPLX Term Loan
Debt Instrument [Line Items]
Long-term debt outstanding	0				1,000
MPLX | Finance Lease
Debt Instrument [Line Items]
Finance lease obligations	$ 11				$ 19
[1]	Borrowed $3.815 billion and repaid $3.640 billion during the year ended December 31, 2020

Debt (Commercial Paper) (Detail

Debt (Commercial Paper) (Details) - Commercial Paper $ in Billions	Feb. 26, 2016USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 2
Debt instrument, term	397 days

Debt (MPC Senior Notes) (Detail

Debt (MPC Senior Notes) (Details) - Senior Notes - USD ($) $ in Millions	Nov. 15, 2020	Oct. 01, 2020	Dec. 31, 2020	Apr. 27, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt outstanding				$ 2,500
Senior notes, 4.500% due May 2023
Debt Instrument [Line Items]
Long-term debt outstanding				1,250
Senior notes, 4.700% due May 2025
Debt Instrument [Line Items]
Long-term debt outstanding				$ 1,250
Marathon Petroleum Corporation
Debt Instrument [Line Items]
Long-term debt outstanding			$ 9,849		$ 8,474
Marathon Petroleum Corporation | Senior notes, 3.400% due December 2020
Debt Instrument [Line Items]
Long-term debt outstanding			0		650
Repayments of debt	$ 650
Marathon Petroleum Corporation | Senior notes, 5.125% due March 2021
Debt Instrument [Line Items]
Long-term debt outstanding			1,000		1,000
Marathon Petroleum Corporation | Senior notes, 5.375% due October 2022
Debt Instrument [Line Items]
Long-term debt outstanding			0		337
Repayments of debt		$ 475
Marathon Petroleum Corporation | Senior notes, 4.500% due May 2023
Debt Instrument [Line Items]
Long-term debt outstanding			1,250		0
Marathon Petroleum Corporation | Senior notes, 4.750% due December 2023
Debt Instrument [Line Items]
Long-term debt outstanding			614		614
Marathon Petroleum Corporation | Senior notes, 5.125% due April 2024
Debt Instrument [Line Items]
Long-term debt outstanding			241		241
Marathon Petroleum Corporation | Senior notes, 3.625% due September 2024
Debt Instrument [Line Items]
Long-term debt outstanding			750		750
Marathon Petroleum Corporation | Senior notes, 4.700% due May 2025
Debt Instrument [Line Items]
Long-term debt outstanding			1,250		0
Marathon Petroleum Corporation | Senior notes, 5.125% due December 2026
Debt Instrument [Line Items]
Long-term debt outstanding			719		719
Marathon Petroleum Corporation | Senior notes, 3.800% due April 2028
Debt Instrument [Line Items]
Long-term debt outstanding			496		496
Marathon Petroleum Corporation | Senior notes, 6.500% due March 2041
Debt Instrument [Line Items]
Long-term debt outstanding			1,250		1,250
Marathon Petroleum Corporation | Senior notes, 4.750% due September 2044
Debt Instrument [Line Items]
Long-term debt outstanding			800		800
Marathon Petroleum Corporation | Senior notes, 5.850% due December 2045
Debt Instrument [Line Items]
Long-term debt outstanding			250		250
Marathon Petroleum Corporation | Senior notes, 4.500% due April 2048
Debt Instrument [Line Items]
Long-term debt outstanding			498		498
Marathon Petroleum Corporation | Senior notes, 5.000%, due September 2054
Debt Instrument [Line Items]
Long-term debt outstanding			400		400
Marathon Petroleum Corporation | Andeavor | Andeavor senior notes, 3.800% - 5.375% due 2022 - 2048
Debt Instrument [Line Items]
Long-term debt outstanding			$ 331		$ 469

Debt (MPLX Term Loan Facility)

Debt (MPLX Term Loan Facility) (Details) $ in Billions	12 Months Ended
	Dec. 31, 2020USD ($)
MPLX | MPLX Term Loan
Debt Instrument [Line Items]
Repayments of debt	$ 1

Debt (MPLX Senior Notes) (Detai

Debt (MPLX Senior Notes) (Details) - USD ($) $ in Millions	Jan. 15, 2021	Dec. 31, 2020	Dec. 31, 2019	Aug. 18, 2020	Apr. 27, 2020	Sep. 23, 2019	Sep. 09, 2019	Jul. 30, 2019
Senior Notes
Debt Instrument [Line Items]
Long-term debt outstanding					$ 2,500
Senior Notes | ANDX
Debt Instrument [Line Items]
Long-term debt outstanding						$ 690
Senior Notes | ANDX | Senior notes, 5.500%, due October 2019
Debt Instrument [Line Items]
Long-term debt outstanding						500
Repayments of debt			$ 500
Interest costs incurred			14
MPLX | MPLX Term Loan
Debt Instrument [Line Items]
Repayments of debt		$ 1,000
MPLX | Senior Notes
Debt Instrument [Line Items]
Long-term debt outstanding		20,350	19,100	$ 3,000			$ 2,000
MPLX | Senior Notes | Floating rate senior notes due September 2021
Debt Instrument [Line Items]
Long-term debt outstanding		0	1,000				1,000
Repayments of debt		1,000
MPLX | Senior Notes | Floating rate senior notes due September 2022
Debt Instrument [Line Items]
Long-term debt outstanding		1,000	1,000				$ 1,000
MPLX | Senior Notes | Senior notes, 6.250% due October 2022
Debt Instrument [Line Items]
Long-term debt outstanding		0	266
Repayments of debt		300
MPLX | Senior Notes | Senior notes, 3.500% due December 2022
Debt Instrument [Line Items]
Long-term debt outstanding		486	486
MPLX | Senior Notes | Senior notes, 3.375% due March 2023
Debt Instrument [Line Items]
Long-term debt outstanding		500	500
MPLX | Senior Notes | Senior notes, 4.500% due July 2023
Debt Instrument [Line Items]
Long-term debt outstanding		989	989
MPLX | Senior Notes | Senior notes, 6.375% due May 2024
Debt Instrument [Line Items]
Long-term debt outstanding		0	381
Repayments of debt		450
MPLX | Senior Notes | Senior notes, 4.875% due December 2024
Debt Instrument [Line Items]
Long-term debt outstanding		1,149	1,149
MPLX | Senior Notes | Senior notes, 5.250% due January 2025
Debt Instrument [Line Items]
Long-term debt outstanding		708	708
MPLX | Senior Notes | Senior notes, 4.000% due February 2025
Debt Instrument [Line Items]
Long-term debt outstanding		500	500
MPLX | Senior Notes | Senior notes, 4.875% due June 2025
Debt Instrument [Line Items]
Long-term debt outstanding		1,189	1,189
MPLX | Senior Notes | Senior notes, 1.750% due March 2026
Debt Instrument [Line Items]
Long-term debt outstanding		1,500	0	1,500
MPLX | Senior Notes | Senior notes, 4.125% due March 2027
Debt Instrument [Line Items]
Long-term debt outstanding		1,250	1,250
MPLX | Senior Notes | Senior notes, 4.250% due December 2027
Debt Instrument [Line Items]
Long-term debt outstanding		732	732
MPLX | Senior Notes | Senior notes, 4.000% due March 2028
Debt Instrument [Line Items]
Long-term debt outstanding		1,250	1,250
MPLX | Senior Notes | Senior notes, 4.800% due February 2029
Debt Instrument [Line Items]
Long-term debt outstanding		750	750
MPLX | Senior Notes | Senior notes, 2.650% due August 2030
Debt Instrument [Line Items]
Long-term debt outstanding		1,500	0	$ 1,500
MPLX | Senior Notes | Senior notes, 4.500% due April 2038
Debt Instrument [Line Items]
Long-term debt outstanding		1,750	1,750
MPLX | Senior Notes | Senior notes, 5.200% due March 2047
Debt Instrument [Line Items]
Long-term debt outstanding		1,000	1,000
MPLX | Senior Notes | Senior notes, 5.200% due December 2047
Debt Instrument [Line Items]
Long-term debt outstanding		487	487
MPLX | Senior Notes | Senior notes, 4.700% due April 2048
Debt Instrument [Line Items]
Long-term debt outstanding		1,500	1,500
MPLX | Senior Notes | Senior notes, 5.500% due February 2049
Debt Instrument [Line Items]
Long-term debt outstanding		1,500	1,500
MPLX | Senior Notes | Senior notes, 4.900% due April 2058
Debt Instrument [Line Items]
Long-term debt outstanding		500	500
MPLX | Senior Notes | Subsequent Event | Senior notes, 5.250% due January 2025
Debt Instrument [Line Items]
Repayments of debt	$ 750
MPLX | Senior Notes | MarkWest | MarkWest senior notes, 4.500% - 5.500% due 2023 - 2025
Debt Instrument [Line Items]
Long-term debt outstanding		23	23
MPLX | Senior Notes | ANDX
Debt Instrument [Line Items]
Long-term debt acquired								$ 3,750
MPLX | Senior Notes | ANDX | ANDX senior notes, 3.500% - 6.375% due 2019 - 2047
Debt Instrument [Line Items]
Long-term debt outstanding		$ 87	$ 190
MPLX | Senior Notes | MPLX
Debt Instrument [Line Items]
Long-term debt outstanding						$ 3,060

Debt (Schedule Of Debt Payments

Debt (Schedule Of Debt Payments) (Details) $ in Millions	Dec. 31, 2020USD ($)
Debt Disclosure [Abstract]
2021	$ 1,750
2022	1,500
2023	3,600
2024	2,376
2025	$ 2,950

Debt (Available Capacity under

Debt (Available Capacity under our Facilities) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Jul. 30, 2019	Jul. 19, 2019
MPC 364-day revolver due September 2021
Line of Credit Facility [Line Items]
Total Capacity		$ 1,000
Outstanding Borrowings		0
Outstanding Letters of Credit		0
Available Capacity		$ 1,000
Weighted Average Interest Rate		0.00%
MPC 364-day revolver due April 2021
Line of Credit Facility [Line Items]
Total Capacity		$ 1,000
Outstanding Borrowings		0
Outstanding Letters of Credit		0
Available Capacity		$ 1,000
Weighted Average Interest Rate		0.00%
MPC 5-year revolver due October 2023
Line of Credit Facility [Line Items]
Total Capacity		$ 5,000
Outstanding Borrowings	[1]	0
Outstanding Letters of Credit		1
Available Capacity		$ 4,999
Weighted Average Interest Rate		0.00%
Proceeds from long-term lines of credit		$ 4,225
Repayments of long-term lines of credit		4,225
Trade Receivables Securitization due July 2021
Line of Credit Facility [Line Items]
Total Capacity		750
Outstanding Borrowings	[2]	0
Outstanding Letters of Credit		0
Available Capacity		$ 750
Weighted Average Interest Rate		0.00%
Proceeds from long-term lines of credit		$ 3,550
Repayments of long-term lines of credit		3,550
Line of credit facility, maximum borrowing capacity		750				$ 750
MPLX revolving credit facility due July 2024 | MPLX
Line of Credit Facility [Line Items]
Total Capacity		3,500			$ 3,500
Outstanding Borrowings		175	[3]	$ 0
Outstanding Letters of Credit		0
Available Capacity		$ 3,325
Weighted Average Interest Rate		1.36%
Proceeds from long-term lines of credit		$ 3,815
Repayments of long-term lines of credit		$ 3,640
[1]	Borrowed $4.225 billion and repaid $4.225 billion during the year ended December 31, 2020.
[2]	Borrowed $3.550 billion and repaid $3.550 billion during the year ended December 31, 2020. Availability under our $750 million trade receivables facility is a function of eligible trade receivables, which will be lower in a sustained lower price environment for refined products.
[3]	Borrowed $3.815 billion and repaid $3.640 billion during the year ended December 31, 2020

Debt (MPC Revolving Credit Agre

Debt (MPC Revolving Credit Agreements) (Details) $ in Millions	Oct. 01, 2018USD ($)Period	Dec. 31, 2020USD ($)	Sep. 23, 2020USD ($)	Apr. 27, 2020USD ($)
MPC 364-day revolver due September 2021
Line of Credit Facility [Line Items]
Total capacity		$ 1,000
MPC 364-day revolver due April 2021
Line of Credit Facility [Line Items]
Total capacity		$ 1,000
Marathon Petroleum Corporation | Bank revolving credit facility due October 2023
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 5,000
Number of renewal periods | Period	2
Marathon Petroleum Corporation | Bank revolving credit facility due October 2023 | Letter of Credit
Line of Credit Facility [Line Items]
Total capacity	$ 2,200
Marathon Petroleum Corporation | Bank revolving credit facility due October 2023 | Maximum
Line of Credit Facility [Line Items]
Line of credit facility additional borrowing capacity	1,000
Marathon Petroleum Corporation | Bank revolving credit facility due October 2023 | Maximum | Bridge Loan
Line of Credit Facility [Line Items]
Total capacity	250
Marathon Petroleum Corporation | Bank revolving credit facility due October 2023 | Maximum | Letter of Credit
Line of Credit Facility [Line Items]
Total capacity	$ 3,000
Marathon Petroleum Corporation | MPC 364-day revolver due September 2021
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 1,000
Marathon Petroleum Corporation | MPC 364-day revolver due April 2021
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity				$ 1,000
Marathon Petroleum Corporation | MPC bank revolving credit facilities
Line of Credit Facility [Line Items]
Debt instrument, description of variable rate basis	at either the Adjusted LIBO Rate or the Alternate Base Rate (both as defined in the MPC credit agreements), plus an applicable margin
Marathon Petroleum Corporation | MPC bank revolving credit facilities | Maximum
Line of Credit Facility [Line Items]
Ratio of indebtedness to net capital	0.65

Debt (Trade Receivables Securit

Debt (Trade Receivables Securitization Facility) (Details) - Trade Receivables Securitization due July 2021 - USD ($) $ in Millions	Dec. 31, 2020	Jul. 19, 2019
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 750	$ 750
Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 750

Debt (MPLX Credit Agreement) (D

Debt (MPLX Credit Agreement) (Details) - MPLX - MPLX revolving credit facility due July 2024 $ in Millions	Jul. 30, 2019USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Total capacity	$ 3,500	$ 3,500
Debt instrument, description of variable rate basis	at the Adjusted LIBO Rate or the Alternate Base Rate (both as defined in the MPLX credit agreement) plus an applicable margin
Maximum
Debt Instrument [Line Items]
Line of credit facility additional borrowing capacity	$ 1,000
Number of prior quarterly reporting periods covenant	4
Covenant ratio debt to EBITDA	5
Covenant ratio debt to EBITDA post acquisition	5.5
Letter of Credit | Maximum
Debt Instrument [Line Items]
Total capacity	$ 300
Bridge Loan | Maximum
Debt Instrument [Line Items]
Total capacity	$ 150

Revenue (Disaggregated by Segme

Revenue (Disaggregated by Segment and Product Line) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Sales and other operating revenues	$ 17,972	$ 17,408	$ 12,195	$ 22,204	$ 28,008	$ 27,552	$ 30,239	$ 25,349	$ 69,779	$ 111,148	$ 86,086
Refined products
Sales and other operating revenues									62,289	103,134	79,897
Crude oil
Sales and other operating revenues									4,023	4,402	3,345
Midstream services and other
Sales and other operating revenues									3,467	3,612	2,844
Refining & Marketing
Sales and other operating revenues									66,180	107,305	82,755
Refining & Marketing | Refined products
Sales and other operating revenues									61,648	102,316	78,952
Refining & Marketing | Crude oil
Sales and other operating revenues									4,023	4,402	3,345
Refining & Marketing | Midstream services and other
Sales and other operating revenues									509	587	458
Midstream
Sales and other operating revenues									3,599	3,843	3,331
Midstream | Refined products
Sales and other operating revenues									641	818	945
Midstream | Crude oil
Sales and other operating revenues									0	0	0
Midstream | Midstream services and other
Sales and other operating revenues									$ 2,958	$ 3,025	$ 2,386

Revenue (Receivables) (Details)

Revenue (Receivables) (Details) $ in Millions	Dec. 31, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Matching buy/sell receivables	$ 2,080

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)		$ 1,235		$ 1,168		$ 887
Net income taxes paid to taxing authorities		(179)		491		424
Payments on operating leases		651		642	[1]	0
Interest payments under finance lease obligations		25	[1]	28	[1]	0
Net cash provided by financing activities included:
Principal payments under finance lease obligations		66	[1]	48	[1]	0
Non-cash investing and financing activities:
Capital leases		0		0		172
Right of use assets obtained in exchange for new operating lease obligations		343	[1]	329	[1]	0
Right of use assets obtained in exchange for new finance lease obligations		110	[1]	80	[1]	0
Contribution of assets	[2]	0		266		0
Fair value of asset acquired		0		525	[3]	0
Acquisition:
Fair value of MPC shares issued		0		0		19,766
Fair value of converted equity awards		$ 0		$ 0		$ 203
[1]	Disclosure added in 2019 following the adoption of ASC 842.
[2]	2019 includes the contribution of net assets to TAMH and Capline LLC. See Note 17.
[3]	2019 includes the recognition of TAMH and Capline LLC equity method investments. See Note 17.

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information (Change in Cash and Cash Equivalents) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	[1]	$ 415	$ 1,393
Restricted cash	[2]	1	2
Cash, cash equivalents and restricted cash		$ 416	$ 1,395	$ 1,519	$ 2,849
[1]	Excludes $140 million and $134 million of cash included in assets held for sale representing Speedway store cash.
[2]	The restricted cash balance is included within other current assets on the consolidated balance sheets.

Supplemental Cash Flow Inform_5

Supplemental Cash Flow Information (Reconciliation Of Additions To Property, Plant And Equipment To Total Capital Expenditures) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Additions to property, plant and equipment per the consolidated statements of cash flows		$ 2,787	$ 4,810	$ 3,179
Asset retirement expenditures		0	1	8
Increase (decrease) in capital accruals		(518)	(303)	268
Total capital expenditures	[1]	$ 2,269	$ 4,508	$ 3,455
[1]	Includes changes in capital expenditure accruals. See Note 24 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Changes in Accumulated Other Comprehensive Loss by Component) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		$ (320)	$ (144)
Other comprehensive income (loss) before reclassifications, net of tax		(199)	(162)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit		(45)	(45)
Amortization– actuarial loss		39	21
Amortization– settlement loss		22	9
Other		(6)	(5)
Tax effect		(3)	6
Other comprehensive income (loss)		(192)	(176)	$ 87
Ending balance		(512)	(320)	(144)
Other comprehensive income (loss) before reclassifications, tax		(65)	(52)
Pension Benefits
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit		(45)	(45)	(33)
Other Benefits
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit		0	0	(3)
Accumulated Defined Benefit Plans Adjustment | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(212)	(132)
Other comprehensive income (loss) before reclassifications, net of tax		(136)	(71)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]	(45)	(45)
Amortization– actuarial loss	[1]	36	22
Amortization– settlement loss	[1]	22	9
Tax effect		(3)	5
Other comprehensive income (loss)		(126)	(80)
Ending balance		(338)	(212)	(132)
Accumulated Defined Benefit Plans Adjustment | Other Benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(116)	(23)
Other comprehensive income (loss) before reclassifications, net of tax		(67)	(92)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]	0	0
Amortization– actuarial loss	[1]	3	(1)
Amortization– settlement loss	[1]	0	0
Tax effect		(1)	0
Other comprehensive income (loss)		(65)	(93)
Ending balance		(181)	(116)	(23)
Gain on Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		1	2
Other comprehensive income (loss) before reclassifications, net of tax		0	0
Amounts reclassified from accumulated other comprehensive loss:
Other		0	(1)
Tax effect		0	0
Other comprehensive income (loss)		0	(1)
Ending balance		1	1	2
Workers Comp
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		7	9
Other comprehensive income (loss) before reclassifications, net of tax		4	1
Amounts reclassified from accumulated other comprehensive loss:
Other		(6)	(4)
Tax effect		1	1
Other comprehensive income (loss)		(1)	(2)	4
Ending balance		$ 6	$ 7	$ 9
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 26.

Pension and Other Postretirem_3

Pension and Other Postretirement Benefits (Cash Balance Pension Plan) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Cash balance weighted average interest crediting rates	3.00%	3.18%	3.00%

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits (Summary Of Defined Benefit Plans With Accumulated Benefit Obligations In Excess Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Projected benefit obligations	$ 3,671	$ 3,220
Accumulated benefit obligations	3,369	3,013
Fair value of plan assets	$ 2,621	$ 2,531

Pension and Other Postretirem_5

Pension and Other Postretirement Benefits (Summary Of Projected Benefit Obligations And Funded Status For Defined Benefit Pension And Other Postretirement Plans) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018
Change in plan assets:
Fair value of plan assets at January 1		$ 2,531
Fair value of plan assets at December 31		2,621		$ 2,531
Amounts recognized in the consolidated balance sheets:
Noncurrent liabilities		(2,121)		(1,617)
Pension Benefits
Change in benefit obligations:
Benefit obligations at January 1		3,220		2,761
Service cost		302		234
Interest cost		98		107	$ 83
Actuarial loss	[1]	373		400
Benefits paid		(322)		(282)
Plan amendments		0		0
Benefit obligations at December 31		3,671		3,220	2,761
Change in plan assets:
Fair value of plan assets at January 1		2,531		2,090
Actual return on plan assets		327		435
Employer contributions		85		288
Benefits paid from plan assets		(322)		(282)
Fair value of plan assets at December 31		2,621		2,531	2,090
Funded status of plans at December 31		(1,050)		(689)
Amounts recognized in the consolidated balance sheets:
Current liabilities		(9)		(47)
Noncurrent liabilities		(1,041)		(642)
Accrued benefit cost		(1,050)		(689)
Pretax amounts recognized in accumulated other comprehensive loss:
Net actuarial loss		699	[2]	577
Prior service cost (credit)		(204)	[2]	(250)
Pension Benefits | LOOP LLC and Explorer Pipeline
Pretax amounts recognized in accumulated other comprehensive loss:
Net actuarial loss		16
Other Benefits
Change in benefit obligations:
Benefit obligations at January 1		1,020		874
Service cost		35		31
Interest cost		32		37	30
Actuarial loss		83		123
Benefits paid		(39)		(43)
Plan amendments		0		(2)
Benefit obligations at December 31		1,131		1,020	874
Change in plan assets:
Fair value of plan assets at January 1		0		0
Actual return on plan assets		0		0
Employer contributions		39		43
Benefits paid from plan assets		(39)		(43)
Fair value of plan assets at December 31		0		0	$ 0
Funded status of plans at December 31		(1,131)		(1,020)
Amounts recognized in the consolidated balance sheets:
Current liabilities		(51)		(46)
Noncurrent liabilities		(1,080)		(974)
Accrued benefit cost		(1,131)		(1,020)
Pretax amounts recognized in accumulated other comprehensive loss:
Net actuarial loss		219	[2]	139
Prior service cost (credit)		32	[2]	$ 32
Other Benefits | LOOP LLC and Explorer Pipeline
Pretax amounts recognized in accumulated other comprehensive loss:
Net actuarial loss		$ 1
[1]	The primary driver of the actuarial loss for the pension plans in 2020 and 2019 was the decrease in interest rates. The plans also saw moderate losses related to demographic experience in each year.
[2]	Amounts exclude those related to LOOP and Explorer, equity method investees with defined benefit pension and postretirement plans for which net losses of $16 million and less than $1 million were recorded in accumulated other comprehensive loss in 2020, reflecting our ownership share.

Pension and Other Postretirem_6

Pension and Other Postretirement Benefits (Components Of Net Periodic Benefit Cost And Other Comprehensive Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):
Amortization of prior service credit		$ 45	$ 45
Pension Benefits
Components of net periodic benefit cost:
Service cost		283	218	$ 147
Interest cost		98	107	83
Expected return on plan assets		(133)	(127)	(109)
Amortization – prior service credit		(45)	(45)	(33)
Amortization – actuarial loss		36	22	31
Amortization – settlement loss		20	9	53
Net periodic benefit cost	[1]	259	184	172
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):
Actuarial (gain) loss		179	92	65
Prior service cost (credit)		0	0	(90)
Amortization of actuarial loss		(56)	(31)	(84)
Amortization of prior service credit		45	45	33
Total recognized in other comprehensive loss		168	106	(76)
Total recognized in net periodic benefit cost and other comprehensive loss		427	290	96
Other Benefits
Components of net periodic benefit cost:
Service cost		35	31	30
Interest cost		32	37	30
Expected return on plan assets		0	0	0
Amortization – prior service credit		0	0	(3)
Amortization – actuarial loss		3	0	1
Amortization – settlement loss		0	0	0
Net periodic benefit cost	[1]	70	68	58
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):
Actuarial (gain) loss		83	123	(72)
Prior service cost (credit)		0	(2)	34
Amortization of actuarial loss		(3)	0	(1)
Amortization of prior service credit		0	0	3
Total recognized in other comprehensive loss		80	121	(36)
Total recognized in net periodic benefit cost and other comprehensive loss		$ 150	$ 189	$ 22
[1]	Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.

Pension and Other Postretirem_7

Pension and Other Postretirement Benefits (Summary Of Assumptions Used To Determine Benefit Obligations And Net Periodic Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Weighted-average assumptions used to determine benefit obligation:
Discount rate	2.44%	3.08%	4.21%
Rate of compensation increase	5.70%	4.90%	5.00%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	3.00%	4.07%	3.89%
Expected long-term return on plan assets	5.75%	6.00%	6.15%
Rate of compensation increase	5.70%	4.90%	4.80%
Other Benefits
Weighted-average assumptions used to determine benefit obligation:
Discount rate	2.55%	3.00%	4.26%
Rate of compensation increase	5.70%	4.90%	5.00%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	3.23%	4.30%	3.72%
Expected long-term return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	5.70%	4.90%	5.00%

Pension and Other Postretirem_8

Pension and Other Postretirement Benefits (Expected Long-Term Return on Plan Assets) (Details)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined benefit plan, plan assets, expected long-term rate-of-return, description	The overall expected long-term return on plan assets assumption is determined based on an asset rate-of-return modeling tool developed by a third-party investment group. The tool utilizes underlying assumptions based on actual returns by asset category and inflation and takes into account our asset allocation to derive an expected long-term rate of return on those assets. Capital market assumptions reflect the long-term capital market outlook. The assumptions for equity and fixed income investments are developed using a building-block approach, reflecting observable inflation information and interest rate information available in the fixed income markets. Long-term assumptions for other asset categories are based on historical results, current market characteristics and the professional judgment of our internal and external investment teams

Pension and Other Postretirem_9

Pension and Other Postretirement Benefits (Summarizes Assumed Health Care Cost Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Medical Pre-65
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for the following year:	6.00%	6.20%	6.80%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate):	4.50%	4.50%	4.50%
Year that the rate reaches the ultimate trend rate:	2028	2027	2027
Prescription drugs
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for the following year:	7.00%	8.10%	9.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate):	4.50%	4.50%	4.50%
Year that the rate reaches the ultimate trend rate:	2028	2027	2027
Medical Post-65 | Maximum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for the following year:	4.00%

Pension and Other Postretire_10

Pension and Other Postretirement Benefits (Plan Investment Policies And Strategies) (Details)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, investment goals	The asset allocation strategy will change over time in response to changes primarily in funded status, which is dictated by current and anticipated market conditions, the independent actions of our investment committee, required cash flows to and from the plans and other factors deemed appropriate. Such changes in asset allocation are intended to allocate additional assets to the fixed income asset class should the funded status improve. The fixed income asset class shall be invested in such a manner that its interest rate sensitivity correlates highly with that of the plans’ liabilities. Other asset classes are intended to provide additional return with associated higher levels of risk. Investment performance and risk is measured and monitored on an ongoing basis through quarterly investment meetings and periodic asset and liability studies.
Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted asset allocation	50.00%
Fixed Income Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted asset allocation	50.00%

Pension and Other Postretire_11

Pension and Other Postretirement Benefits (Fair Values Of Defined Benefit Pension Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	$ 2,621	$ 2,531
Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	731	644
Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	1,828	1,814
Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	62	73
Cash and cash equivalents
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	23	22
Cash and cash equivalents | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Cash and cash equivalents | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	23	22
Cash and cash equivalents | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Common stocks
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	54	260
Common stocks | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	51	125
Common stocks | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	3	135
Common stocks | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Mutual funds
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	353	188
Mutual funds | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	353	188
Mutual funds | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Mutual funds | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Pooled funds
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	794	442
Pooled funds | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Pooled funds | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	794	442
Pooled funds | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Corporate
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	746	975
Corporate | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	160
Corporate | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	746	815
Corporate | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Government
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	455	330
Government | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	327	113
Government | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	128	217
Government | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Pooled funds
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	131	229
Pooled funds | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Pooled funds | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	131	229
Pooled funds | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Private equity
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	23	30
Private equity | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Private equity | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Private equity | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	23	30	$ 41
Real estate
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	20	24
Real estate | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Real estate | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	0
Real estate | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	20	24	$ 29
Other
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	22	31
Other | Level 1
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	0	58
Other | Level 2
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	3	(46)
Other | Level 3
Defined Benefit Plan, Plan Assets, Allocation [Line Items]
Plan asset investments, at fair value	$ 19	$ 19

Pension and Other Postretire_12

Pension and Other Postretirement Benefits (Reconciliation Of Beginning And Ending Balances Of Plan Assets Classified As Level 3) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	$ 2,531
Actual return on plan assets:
Fair value of plan assets at December 31	2,621	$ 2,531
Private equity
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	30
Actual return on plan assets:
Fair value of plan assets at December 31	23	30
Real estate
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	24
Actual return on plan assets:
Fair value of plan assets at December 31	20	24
Level 3
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	73
Actual return on plan assets:
Fair value of plan assets at December 31	62	73
Level 3 | Private equity
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	30	41
Actual return on plan assets:
Realized	6	5
Unrealized	(4)	(3)
Purchases	0	1
Sales	(9)	(14)
Fair value of plan assets at December 31	23	30
Level 3 | Real estate
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	24	29
Actual return on plan assets:
Realized	1	2
Unrealized	(3)	(2)
Purchases	1	1
Sales	(3)	(6)
Fair value of plan assets at December 31	20	24
Level 3 | Other
Defined Benefit Plan, Plan Assets, Level 3 Reconciliation [Line Items]
Fair value of plan assets at January 1	19	18
Actual return on plan assets:
Realized	0	0
Unrealized	0	1
Purchases	0	0
Sales	0	0
Fair value of plan assets at December 31	$ 19	$ 19

Pension and Other Postretire_13

Pension and Other Postretirement Benefits (Contributions To Defined Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to defined contribution plans	$ 180	$ 181	$ 118
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension contributions	$ 3
Expected future employer contributions, next fiscal year, description	For 2021, we have $65 million of required funding, but we may also make voluntary contributions to our funded pension plans at our discretion.
Unfunded Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plans, estimated future employer contributions in next fiscal year	$ 82
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plans, estimated future employer contributions in next fiscal year	$ 52

Pension and Other Postretire_14

Pension and Other Postretirement Benefits (Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2020USD ($)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2021	$ 185
2022	189
2023	194
2024	206
2025	212
2026 through 2030	1,172
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2021	52
2022	52
2023	52
2024	52
2025	53
2026 through 2030	$ 280

Pension and Other Postretire_15

Pension and Other Postretirement Benefits (Multi Employee Plans) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)Plan	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Number of multiemployer defined benefit pension or health and welfare plan	1
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Number of multiemployer defined benefit pension or health and welfare plan	1
Employer contribution cost | $	$ 7	$ 6	$ 6

Pension and Other Postretire_16

Pension and Other Postretirement Benefits (Multi Employer Pension Plan) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Employee		Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Multiemployer Plan [Line Items]
Multiemployer Plan, Pension, Insignificant, Certified Zone Status [Fixed List]	Red		Red
Funding improvement plan and rehabilitation plan	Implemented
Surcharge - imposed	No
Pension Benefits
Multiemployer Plan [Line Items]
Multiemployer pension plan, minimum contribution requirement per week per employee	$ 338
Number of employees participated in the plan | Employee	275
Pension Benefits | Central States, Southeast and Southwest Pension Plan
Multiemployer Plan [Line Items]
Multiemployer Plan, Pension, Insignificant, Employer Contribution, Cost	$ 5,000,000	[1]	$ 4,000,000	$ 4,000,000
[1]	This agreement has a minimum contribution requirement of $338 per week per employee for 2021. A total of 275 employees participated in the plan as of December 31, 2020.

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) shares in Millions	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, expiration period	10 years
Vesting period of awards	3 years
Restricted Stock Awards and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards	3 years
Restricted stock and restricted stock unit awards granted in 2012, additional holding period	1 year
Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target payout | $ / shares	$ 1
Maximum | Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Actual payout | $ / shares	$ 2
Target payout percentage	200.00%
MPC 2012 Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock authorized to be delivered under the compensation plan	50
MPC 2012 Plan | Maximum | Awards Other Than Stock Options Or Stock Appreciation Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock authorized to be delivered under the compensation plan	20
MPC 2012 Plan | Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock authorized to be delivered under the compensation plan	20
MPC 2012 and 2011 Plans | Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards	36 months
Pay-out percentage in MPC common stock (in percentage)	25.00%
Pay-out percentage in cash (in percentage)	75.00%

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Stock-based compensation expense	$ 100	$ 153	$ 127
Tax benefit recognized on stock-based compensation expense	25	35	31
Cash received by MPC upon exercise of stock option awards	11	10	24
Tax (expense)/benefit received for tax deductions for stock awards exercised	$ 16	$ (3)	$ 14

Stock-Based Compensation (Weigh

Stock-Based Compensation (Weighted Average Assumptions Used To Value Stock Options Awards) (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price per share	$ 28.78	$ 61.92	$ 67.71
Expected life in years	5 years 10 months 24 days	6 years	6 years 2 months 12 days
Expected volatility	39.00%	32.00%	34.00%
Expected dividend yield	4.70%	3.40%	3.00%
Risk-free interest rate	0.60%	2.40%	2.70%
Weighted average grant date fair value of stock option awards granted	$ 7.40	$ 13.65	$ 17.21
Implied volatility rate weighting (in percentage)	50.00%
Historical volatility rate weighting (in percentage)	50.00%

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary Of Stock Option Award Activity) (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised	$ 25	$ 23	$ 44
Unrecognized compensation cost	$ 15
Weighted average recognition period, in years	1 year 9 months 18 days
Number of  Shares
Outstanding, beginning balance	10,018,367
Granted	2,770,139
Exercised	(1,016,593)
Forfeited or expired	(472,132)
Outstanding, ending balance	11,299,781	10,018,367
Vested and expected to vest at December 31, 2020 (in shares)	11,243,905
Exercisable at December 31, 2020 (in shares)	7,641,774
Weighted Average Exercise Price
Outstanding, beginning balance (in USD per share)	$ 42.55
Granted (in USD per share)	28.78	$ 61.92	$ 67.71
Exercised (in USD per share)	14.15
Forfeited or expired (in USD per share)	37.77
Outstanding, ending balance (in USD per share)	41.95	$ 42.55
Vested and expected to vest at December 31, 2020 (in USD per share)	29.28
Exercisable at December 31, 2020 (in USD per share)	$ 42.61
Weighted Average Remaining Contractual Terms (in years)
Vested and expected to vest at December 31, 2020 (in years)	5 years 2 months 12 days
Exercisable at December 31, 2020 (in years)	3 years 7 months 6 days
Aggregate Intrinsic Value (in millions)
Vested and expected to vest at December 31, 2020 (in USD)	$ 76
Exercisable at December 31, 2020 (in USD)	$ 42

Stock-Based Compensation (Sum_2

Stock-Based Compensation (Summary Of Restricted Stock Award Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock
Number of Shares
Unvested, beginning balance	1,349,798
Granted	2,463
Vested	(646,358)
Forfeited	(125,924)
Unvested, ending balance	579,979	1,349,798
Weighted Average Grant Date Fair Value
Unvested, beginning balance (in USD per share)	$ 62.20
Granted (in USD per share)	56.49	$ 61.14	$ 71.19
Vested (in USD per share)	61.58
Forfeited (in USD per share)	62.11
Unvested, ending balance (in USD per share)	$ 62.89	$ 62.20
Restricted Stock Units
Number of Shares
Unvested, beginning balance	1,481,746
Granted	3,076,347
Vested	(823,111)
Forfeited	(410,658)
Unvested, ending balance	3,324,324	1,481,746
Weighted Average Grant Date Fair Value
Unvested, beginning balance (in USD per share)	$ 82.39
Granted (in USD per share)	22.82	$ 58.30	$ 72.43
Vested (in USD per share)	77.01
Forfeited (in USD per share)	27.76
Unvested, ending balance (in USD per share)	$ 35.34	$ 82.39

Stock-Based Compensation (Sum_3

Stock-Based Compensation (Summary Of Values Related To Vested And Unvested Restricted Stock Awards) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic Value of Awards Vested During the Period (in millions)	$ 18	$ 32	$ 49
Grant date fair value of performance units granted	$ 56.49	$ 61.14	$ 71.19
Unrecognized compensation cost	$ 19
Weighted average recognition period, in years	1 year
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic Value of Awards Vested During the Period (in millions)	$ 59	$ 120	$ 39
Grant date fair value of performance units granted	$ 22.82	$ 58.30	$ 72.43
Unrecognized compensation cost	$ 43
Weighted average recognition period, in years	1 year 9 months 3 days

Stock-Based Compensation (Sum_4

Stock-Based Compensation (Summary Of Performance Unit Awards) (Details) - Performance Unit Awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued in period	320,661
Unrecognized compensation cost	$ 2
Weighted average recognition period, in years	1 year 11 months 8 days
Number of Shares
Unvested, beginning balance	11,199,500
Granted	3,360,000
Vested	(3,490,750)
Forfeited	(58,713)
Unvested, ending balance	11,010,037	11,199,500
Weighted Average Grant Date Fair Value
Unvested, beginning balance (in USD per share)	$ 0.80
Granted (in USD per share)	0.89	$ 0.72	$ 0.83
Vested (in USD per share)	0.89
Forfeited (in USD per share)	0.75
Unvested, ending balance (in USD per share)	$ 0.80	$ 0.80

Stock-Based Compensation (Wei_2

Stock-Based Compensation (Weighted Average Assumptions Used to Value Performance Unit Awards) (Details) - Performance Unit Awards - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.90%	2.50%	2.30%
Look-back period (in years)	2.8	2.8	2.8
Expected volatility	30.40%	29.70%	34.00%
Grant date fair value of performance units granted	$ 0.89	$ 0.72	$ 0.83

Leases (Lessee Narrative) (Deta

Leases (Lessee Narrative) (Details)	12 Months Ended
	Dec. 31, 2020
Minimum
Term of agreements	1 year
Renewal term agreement	1 year
Maximum
Term of agreements	58 years
Renewal term agreement	49 years

Leases (Components of Lease Cos

Leases (Components of Lease Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finance lease cost:
Amortization of right of use assets	$ 72	$ 59
Interest on lease liabilities	35	37
Operating lease cost	658	660
Variable lease cost	60	68
Short-term lease cost	631	735
Total lease cost	$ 1,456	$ 1,559

Leases (Supplemental Balance Sh

Leases (Supplemental Balance Sheet Disclosure) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets
Right of use assets	$ 1,521	$ 1,806
Liabilities
Operating lease liabilities	497	514
Long-term operating lease liabilities	1,014	1,300
Total operating lease liabilities	$ 1,511	$ 1,814
Weighted average remaining lease term (in years)	4 years 9 months 18 days	5 years 1 month 6 days
Weighted average discount rate	3.68%	3.91%
Assets
Property, plant and equipment, gross	$ 819	$ 740
Less accumulated depreciation	272	215
Property, plant and equipment, net	547	525
Liabilities
Debt due within one year	69	56
Long-term debt	576	537
Total finance lease liabilities	$ 645	$ 593
Weighted average remaining lease term (in years)	10 years 8 months 12 days	11 years 7 months 6 days
Weighted average discount rate	5.33%	6.63%

Leases (Schedule Of Future Mini

Leases (Schedule Of Future Minimum Commitments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating
2021	$ 544
2022	373
2023	243
2024	170
2025	111
2026 and thereafter	224
Gross lease payments	1,665
Less: imputed interest	154
Total operating lease liabilities	1,511	$ 1,814
Finance
2021	91
2022	99
2023	101
2024	84
2025	76
2026 and thereafter	402
Gross lease payments	853
Less: imputed interest	208
Finance lease obligations	$ 645	$ 593

Leases (Lessor Narrative) (Deta

Leases (Lessor Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease revenue	$ 273	$ 254	$ 221

Leases (Minimum Future Rentals

Leases (Minimum Future Rentals On The Non-Cancellable Operating Leases) (Details) $ in Millions	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 186
2022	181
2023	178
2024	174
2025	142
2026 and thereafter	999
Total minimum future rentals	$ 1,860

Leases (Investments In Assets H

Leases (Investments In Assets Held For Operating Lease By Major Classes) (Details) - USD ($) $ in Millions	Dec. 31, 2020		Dec. 31, 2019
Operating Leased Assets [Line Items]
Property, plant and equipment	$ 59,339		$ 57,586
Accumulated depreciation	20,304	[1]	16,716
Property, plant and equipment, net	39,035		40,870
Assets held for operating lease
Operating Leased Assets [Line Items]
Property, plant and equipment	2,000		1,935
Accumulated depreciation	430		327
Property, plant and equipment, net	1,570		1,608
Assets held for operating lease | Gathering and transportation
Operating Leased Assets [Line Items]
Property, plant and equipment	990		980
Assets held for operating lease | Processing and fractionation
Operating Leased Assets [Line Items]
Property, plant and equipment	867		855
Assets held for operating lease | Terminals
Operating Leased Assets [Line Items]
Property, plant and equipment	128		83
Assets held for operating lease | Land, building and other
Operating Leased Assets [Line Items]
Property, plant and equipment	$ 15		$ 17
[1]	The December 31, 2020 balance includes property, plant and equipment impairment charges recorded during 2020. See Note 7 for additional information.

Commitments and Contingencies (

Commitments and Contingencies (Details)	12 Months Ended
	Dec. 31, 2020
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, inestimable loss	For matters for which we have not recorded a liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings

Commitments and Contingencies_2

Commitments and Contingencies (Environmental Matters) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Accrued liabilities for remediation	$ 397	$ 396
Receivables for recoverable costs	$ 7	$ 9

Commitments and Contingencies_3

Commitments and Contingencies (Asset Retirement Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Asset retirement obligation, current	$ 14	$ 20
Asset retirement obligations, noncurrent	$ 183	$ 184

Commitments and Contingencies_4

Commitments and Contingencies (Other Legal Proceedings) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Loss Contingency, Damages Sought, Value	$ 187
Loss Contingency, Damages Paid, Value	$ 4

Commitments and Contingencies_5

Commitments and Contingencies (Guarantees) (Details) $ in Millions	Dec. 31, 2020USD ($)
Crowley Blue Water Partners
Loss Contingencies [Line Items]
Equity method investments, ownership percentage	50.00%
Financial Guarantee | Guarantee of Indebtedness of Others | LOOP and LOCAP LLC
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 171
Financial Guarantee | Guarantee of Indebtedness of Others | Bakken Pipeline System
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	230
Financial Guarantee | Guarantee of Indebtedness of Others | Crowley Ocean Partners
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	119
Financial Guarantee | Guarantee of Indebtedness of Others | Crowley Blue Water Partners
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	115
Other Guarantees
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	99
Guarantee of Indebtedness of Others | Financial Guarantee | Crowley Ocean Partners | Crowley Term Loan
Loss Contingencies [Line Items]
Line of credit facility, maximum borrowing capacity	$ 325
Indirect | Bakken Pipeline System
Loss Contingencies [Line Items]
Equity method investments, ownership percentage	9.19%

Commitments and Contingencies_6

Commitments and Contingencies (Contractual Commitments and Contingencies) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	$ 1,700	$ 1,600

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Schedule Of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Sales and other operating revenues	$ 17,972		$ 17,408		$ 12,195		$ 22,204		$ 28,008		$ 27,552		$ 30,239		$ 25,349		$ 69,779	$ 111,148	$ 86,086
Income (loss) from continuing operations	390		(1,057)		575		(12,155)		558		1,680		1,698		526		(12,247)	4,462	4,690
Income (loss) from continuing operations, net of tax	250		(980)		84		(10,536)		77		1,113		1,109		150		(11,182)	2,449	2,933
Net income (loss)	574		(609)		276		(10,218)		262		1,367		1,367		259		(9,977)	3,255	3,606
Net income (loss) attributable to MPC	$ 285		$ (886)		$ 9		$ (9,234)		$ 443		$ 1,095		$ 1,106		$ (7)		$ (9,826)	$ 2,637	$ 2,780
Income (loss) from continuing operations per share:
Basic (in USD per share)	$ (0.06)	[1]	$ (1.93)	[1]	$ (0.28)	[1]	$ (14.74)	[1]	$ 0.40	[1]	$ 1.28	[1]	$ 1.28	[1]	$ (0.17)	[1]	$ (16.99)	$ 2.78	$ 4.06
Diluted (in USD per share)	$ (0.06)	[1]	$ (1.93)	[1]	$ (0.28)	[1]	$ (14.74)	[1]	$ 0.40	[1]	$ 1.27	[1]	$ 1.27	[1]	$ (0.17)	[1]	$ (16.99)	$ 2.76	$ 4
[1]	The sum of the per-share amounts for the four quarters may not always equal the annual per-share amounts due to differences in the average number of shares outstanding during the respective periods.