Marathon Petroleum (MPC) 10-Q 4 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Jul. 30, 2021
Cover [Abstract]
Entity Central Index Key	0001510295
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q2
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		638,202,178

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues and other income:
Sales and other operating revenues	$ 29,615	$ 12,195	$ 52,326	$ 34,399
Income (loss) from equity method investments	93	79	184	(1,154)	[1]
Net gain on disposal of assets	0	2	3	5
Other income	119	24	196	47
Total revenues and other income	29,827	12,300	52,709	33,297
Costs and expenses:
Cost of revenues (excludes items below)	27,177	11,502	48,261	31,844
LCM inventory valuation adjustment	0	(1,470)	0	1,715
Impairment expense	0	25	0	7,847
Depreciation and amortization	871	833	1,715	1,696
Selling, general and administrative expenses	625	665	1,200	1,407
Other taxes	189	170	351	368
Total costs and expenses	28,862	11,725	51,527	44,877
Income (loss) from continuing operations	965	575	1,182	(11,580)
Net interest and other financial costs	372	341	725	673
Income (loss) from continuing operations before income taxes	593	234	457	(12,253)
Provision (benefit) for income taxes on continuing operations	5	150	39	(1,801)
Income (loss) from continuing operations, net of tax	588	84	418	(10,452)
Income from discontinued operations, net of tax	8,214	192	8,448	510
Net income (loss)	8,802	276	8,866	(9,942)
Less net income (loss) attributable to:
Redeemable noncontrolling interest	21	21	41	41
Noncontrolling interests	269	246	555	(758)
Net income (loss) attributable to MPC	$ 8,512	$ 9	$ 8,270	$ (9,225)
Basic:
Continuing operations	$ 0.46	$ (0.28)	$ (0.27)	$ (15)
Discontinued operations	12.63	0.29	12.98	0.79
Net income (loss) per share	$ 13.09	$ 0.01	$ 12.71	$ (14.21)
Weighted average shares outstanding	650	650	651	649
Diluted:
Continuing operations	$ 0.45	$ (0.28)	$ (0.27)	$ (15)
Discontinued operations	12.55	0.29	12.98	0.79
Net income (loss) per share	$ 13	$ 0.01	$ 12.71	$ (14.21)
Weighted average shares outstanding	654	650	651	649
[1]	The three and six months ended June 30, 2021 and the

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net income (loss)	$ 8,802	$ 276	$ 8,866	$ (9,942)
Other comprehensive income (loss)	171	(10)	172	(16)
Comprehensive income (loss)	8,973	266	9,038	(9,958)
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	21	21	41	41
Noncontrolling interests	269	246	555	(758)
Comprehensive income (loss) attributable to MPC	8,683	(1)	8,442	(9,241)
Actuarial changes
Other comprehensive income (loss)	183	(1)	192	3
Prior service
Other comprehensive income (loss)	(8)	(8)	(16)	(17)
Other
Other comprehensive income (loss)	$ (4)	$ (1)	$ (4)	$ (2)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Actuarial changes
OCI, tax expense (benefit)	$ 61	$ 0	$ 64	$ 1
Prior service
OCI, tax expense (benefit)	(2)	(3)	(5)	(6)
Other
OCI, tax expense (benefit)	$ (2)	$ (1)	$ (2)	$ (1)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	[1]	$ 11,839	$ 415
Short-term investments		5,418	0
Receivables, less allowance for doubtful accounts of $44 and $18, respectively		9,771	5,760
Inventories		8,879	7,999
Other current assets		2,685	2,724
Assets held for sale		0	11,389
Total current assets		38,592	28,287
Equity method investments		5,424	5,422
Property, plant and equipment, net		37,996	39,035
Goodwill		8,256	8,256
Right of use assets		1,500	1,521
Other noncurrent assets		2,532	2,637
Total assets		94,300	85,158
Current liabilities:
Accounts payable		12,170	7,803
Payroll and benefits payable		651	732
Accrued taxes		5,219	1,105
Debt due within one year		70	2,854
Operating lease liabilities		473	497
Other current liabilities		929	822
Liabilities held for sale		0	1,850
Total current liabilities		19,512	15,663
Long-term debt		28,250	28,730
Deferred income taxes		5,704	6,203
Defined benefit postretirement plan obligations		1,850	2,121
Long-term operating lease liabilities		1,020	1,014
Deferred credits and other liabilities		1,271	1,207
Total liabilities		57,607	54,938
Commitments and contingencies (see Note 24)
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 – 983 million and 980 million shares (par value $0.01 per share, 2 billion shares authorized)		10	10
Held in treasury, at cost – 345 million and 329 million shares		(16,147)	(15,157)
Additional paid-in capital		33,238	33,208
Retained earnings		12,160	4,650
Accumulated other comprehensive loss		(340)	(512)
Total MPC stockholders’ equity		28,921	22,199
Noncontrolling interests		6,804	7,053
Total equity		35,725	29,252
Total liabilities, redeemable noncontrolling interest and equity		$ 94,300	$ 85,158
[1]	Excludes $140 million of cash at December 31, 2020, representing Speedway store cash, which was included in assets held for sale.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 44	$ 18
Preferred stock:
Preferred Stock, Shares Issued	0
Preferred Stock, Shares Outstanding	0
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Preferred Stock, Shares Authorized	30,000,000
Common stock:
Common Stock, Shares, Issued	983,000,000	980,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01
Common Stock, Shares Authorized	2,000,000,000
Treasury Stock, Shares	(345,000,000)	(329,000,000)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020
Operating activities:
Net income (loss)		$ 8,866	$ (9,942)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization of deferred financing costs and debt discount		41	30
Impairment expense		0	7,847
Depreciation and amortization		1,715	1,696
LCM inventory valuation adjustment		0	1,715
Pension and other postretirement benefits, net		(34)	102
Deferred income taxes		(49)	(529)
Net gain on disposal of assets		(3)	(5)
(Income) loss from equity method investments		(184)	1,154	[1]
Distributions from equity method investments		303	275
Income from discontinued operations		(8,448)	(510)
Changes in income tax receivable		20	(1,150)
Net recognized (gains) losses on investments and derivatives		(1)	23
Changes in operating assets and liabilities, net of effects of businesses acquired:
Current receivables		(3,947)	3,095
Inventories		(880)	415
Current accounts payable and accrued liabilities		4,477	(5,188)
Right of use assets and operating lease liabilities, net		4	0
All other, net		(79)	(48)
Cash provided by (used in) operating activities - continuing operations		1,801	(1,020)
Cash provided by operating activities - discontinued operations		33	790
Net cash provided by (used in) operating activities		1,834	(230)
Investing activities:
Additions to property, plant and equipment		(606)	(1,696)
Disposal of assets		81	58
Investments – acquisitions and contributions		(113)	(383)
Investments - redemptions, repayments and return of capital		3	118
Purchases of short-term investments		(5,417)	0
All other, net		220	19
Cash used in investing activities - continuing operations		(5,832)	(1,884)
Cash provided by (used in) investing activities - discontinued operations		21,235	(193)
Net cash provided by (used in) investing activities		15,403	(2,077)
Financing activities:
Commercial paper – issued		7,414	0
Commercial paper - repayments		(8,437)	0
Long-term debt – borrowings		10,775	9,672
Long-term debt – repayments		(13,056)	(6,388)
Debt issuance costs		0	(24)
Issuance of common stock		53	6
Common stock repurchased		(984)	0
Dividends paid		(760)	(755)
Distributions to noncontrolling interests		(613)	(620)
Repurchases of noncontrolling interests		(310)	0
All other, net		(36)	(20)
Net cash provided by (used in) financing activities		(5,954)	1,871
Net change in cash, cash equivalents and restricted cash		11,283	(436)
Cash, cash equivalents, restricted cash and restricted cash equivalents, beginning balance		416	1,395
Cash, cash equivalents, restricted cash and restricted cash equivalents, ending balance		11,839	966
Discontinued Operations, Held-for-sale
Financing activities:
Cash, cash equivalents, restricted cash and restricted cash equivalents, beginning balance	[2]	140	134
Cash, cash equivalents, restricted cash and restricted cash equivalents, ending balance	[2]	$ 0	$ 127
[1]	The three and six months ended June 30, 2021 and the
[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	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests
Beginning 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)	(10,238)				(9,234)		(1,004)
Dividends declared on common stock	(377)				(377)
Distributions to noncontrolling interests	(300)						(300)
Other comprehensive income (loss)	(6)					(6)
Shares returned - stock based compensation			(2)
Shares issued - stock based compensation				17
Net shares issued - stock based compensation	16						1
Equity transactions of MPLX	(7)			(5)			(2)
Other	1				1		0
Ending balance at Mar. 31, 2020	31,228	10	(15,145)	33,169	6,380	(326)	7,140
Beginning balance at Dec. 31, 2019	42,139	10	(15,143)	33,157	15,990	(320)	8,445
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(16)
Equity transactions of MPLX				3
Ending balance at Jun. 30, 2020	30,849	10	(15,149)	33,208	6,008	(336)	7,108
Beginning balance at Mar. 31, 2020	31,228	10	(15,145)	33,169	6,380	(326)	7,140
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	255				9		246
Dividends declared on common stock	(380)				(380)
Distributions to noncontrolling interests	(279)						(279)
Other comprehensive income (loss)	(10)					(10)
Shares returned - stock based compensation			(4)
Shares issued - stock based compensation				31
Net shares issued - stock based compensation	30						3
Equity transactions of MPLX	6			8			(2)
Other	(1)				(1)		0
Ending balance at Jun. 30, 2020	30,849	10	(15,149)	33,208	6,008	(336)	7,108
Beginning balance at Dec. 31, 2020	29,252	10	(15,157)	33,208	4,650	(512)	7,053
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	44				(242)		286
Dividends declared on common stock	(379)				(379)
Distributions to noncontrolling interests	(300)						(300)
Other comprehensive income (loss)	1					1
Shares returned - stock based compensation			(1)
Shares issued - stock based compensation				18
Net shares issued - stock based compensation	17						0
Equity transactions of MPLX	(124)			(4)			(120)
Ending balance at Mar. 31, 2021	28,511	10	(15,158)	33,222	4,029	(511)	6,919
Beginning balance at Dec. 31, 2020	29,252	10	(15,157)	33,208	4,650	(512)	7,053
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	172
Equity transactions of MPLX				(38)
Ending balance at Jun. 30, 2021	35,725	10	(16,147)	33,238	12,160	(340)	6,804
Beginning balance at Mar. 31, 2021	28,511	10	(15,158)	33,222	4,029	(511)	6,919
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	8,781				8,512		269
Dividends declared on common stock	(381)				(381)
Distributions to noncontrolling interests	(272)						(272)
Other comprehensive income (loss)	171					171
Shares repurchased	(984)		(984)
Shares returned - stock based compensation			(5)
Shares issued - stock based compensation				50
Net shares issued - stock based compensation	47						2
Equity transactions of MPLX	(148)			(34)			(114)
Ending balance at Jun. 30, 2021	$ 35,725	$ 10	$ (16,147)	$ 33,238	$ 12,160	$ (340)	$ 6,804

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, 2019		978
Number of common shares issued - stock compensation		1
Ending balance at Mar. 31, 2020		979
Number of common shares issued - stock compensation		0
Ending balance at Jun. 30, 2020		979
Beginning balance at Dec. 31, 2020	980	980
Number of common shares issued - stock compensation		1
Ending balance at Mar. 31, 2021		981
Number of common shares issued - stock compensation		2
Ending balance at Jun. 30, 2021	983	983

Consolidated Statements of Eq_3

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Shares of Treasury Stock) - shares shares in Millions	Total	Treasury Stock
Beginning balance at Dec. 31, 2019		(329)
Number of shares returned - stock compensation		0
Ending balance at Mar. 31, 2020		(329)
Number of shares returned - stock compensation		0
Ending balance at Jun. 30, 2020		(329)
Beginning balance at Dec. 31, 2020	(329)	(329)
Number of shares returned - stock compensation		0
Ending balance at Mar. 31, 2021		(329)
Number of shares repurchased		(16)
Number of shares returned - stock compensation		0
Ending balance at Jun. 30, 2021	(345)	(345)

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, 2019		$ 968
Net income attributable to redeemable noncontrolling interest		20
Distributions to noncontrolling interests		(20)
Ending balance at Mar. 31, 2020		968
Beginning balance at Dec. 31, 2019		968
Net income attributable to redeemable noncontrolling interest	$ 41
Ending balance at Jun. 30, 2020		968
Beginning balance at Mar. 31, 2020		968
Net income attributable to redeemable noncontrolling interest	21	21
Distributions to noncontrolling interests		(21)
Ending balance at Jun. 30, 2020		968
Beginning balance at Dec. 31, 2020	968	968
Net income attributable to redeemable noncontrolling interest		20
Distributions to noncontrolling interests		(20)
Ending balance at Mar. 31, 2021		968
Beginning balance at Dec. 31, 2020	968	968
Net income attributable to redeemable noncontrolling interest	41
Ending balance at Jun. 30, 2021	968	968
Beginning balance at Mar. 31, 2021		968
Net income attributable to redeemable noncontrolling interest	21	21
Distributions to noncontrolling interests		(21)
Ending balance at Jun. 30, 2021	$ 968	$ 968

Consolidated Statements of Eq_5

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Dividends declared per share of common stock (in dollars per share)	$ 0.58	$ 0.58	$ 0.58	$ 0.58

Description of the Business and

Description of the Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2021
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 branded outlets. We also sell transportation fuel to consumers through 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 May 14, 2021, we completed the sale of Speedway, our company-owned and operated retail transportation fuel and convenience store business, to 7-Eleven, Inc. (“7-Eleven”). Speedway’s 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 are presented in our consolidated balance sheets as assets and liabilities held for sale as of December 31, 2020. 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 4 for discontinued operations disclosures. Basis of Presentation All significant intercompany transactions and accounts have been eliminated. These interim consolidated financial statements are unaudited; however, in the opinion of our management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020. The results of operations for the three and six months ended June 30, 2021 are not necessarily indicative of the results to be expected for the full year. 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 continue to supply fuel to Speedway subsequent to the sale to 7-Eleven. All periods presented have been retrospectively adjusted through the sale date of May 14, 2021 to reflect this change. 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. During the second quarter of 2021, we invested a significant portion of the Speedway sale proceeds in investment grade debt, commercial paper and certificates of deposit with maturities greater than three months. As a result, we have updated our accounting policies for short-term investments and fair value as disclosed below: Short-Term Investments Investments with a maturity date greater than three months that we intend to convert to cash or cash equivalents within a year or less are classified as short-term investments in our consolidated balance sheets. Additionally, in accordance with ASC 320, Investments - Debt Securities, we have classified all short-term investments as of June 30, 2021 as available-for-sale securities and changes in fair market value are reported in other comprehensive income. Fair Value We account for certain assets and liabilities at fair value. The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. We categorize each of our fair value measurements in one of these three levels based on the lowest level input that is significant to the fair value measurement in its entirety. These levels are: • Level 1 – inputs are based upon unadjusted quoted prices for identical instruments in active markets. Our Level 1 derivative assets and liabilities include 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. • Level 2 – inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs including interest rate curves, credit spreads, and forward and spot prices for currencies. Our Level 2 investments include commercial paper, certificates of deposit, time deposits and corporate notes and bonds. Our Level 2 derivative assets and liabilities primarily include certain OTC contracts. • Level 3 – inputs are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are therefore determined using model-based techniques, including option pricing models and discounted cash flow models. Our Level 3 assets and liabilities include goodwill, long-lived assets and intangible assets, when they are recorded at fair value due to an impairment charge and an 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 June 30, 2021 used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.64 to $1.59 per gallon with a weighted average of $0.81 per gallon and (2) the probability of renewal of 100 percent for the first and second five

Accounting Standards

Accounting Standards	6 Months Ended
	Jun. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Standards	ACCOUNTING STANDARDS Recently Adopted We adopted the following ASU during the first six months of 2021, which did not have a material impact to our financial statements or financial statement disclosures: ASU Effective Date 2019-12 Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes January 1, 2021

Short-term Investments

Short-term Investments	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Short-term Investments	SHORT-TERM INVESTMENTS Investments Components The components of investments were as follows: June 30, 2021 (In millions) Fair Value Level Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash and Cash Equivalents Short-term Investments Available-for-sale debt securities Commercial paper Level 2 $ 8,378 $ — $ — $ 8,378 $ 3,907 $ 4,471 Certificates of deposit and time deposits Level 2 4,501 — — 4,501 3,625 876 U.S. government securities Level 1 50 — — 50 50 — Corporate notes and bonds Level 2 248 — — 248 177 71 Total available-for-sale debt securities $ 13,177 $ — $ — $ 13,177 $ 7,759 $ 5,418 Cash 4,080 4,080 — Total $ 17,257 $ 11,839 $ 5,418 Our investment policy includes concentration limits and credit rating requirements which limits our investments to high quality, short term and highly liquid securities. Unrealized losses on debt investments held from May 14, 2021 to June 30, 2021 were not material. Realized gains/losses were not material. All of our available-for-sale debt securities held as of June 30, 2021 mature within one year or less.

Discontinued Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 2021
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	DISCONTINUED OPERATIONS On May 14, 2021, we completed the sale of Speedway, our company-owned and operated retail transportation fuel and convenience store business, to 7-Eleven for cash proceeds of approximately $21.38 billion. After-tax proceeds were approximately $17.22 billion. This transaction resulted in a pretax gain of $11.68 billion ($8.02 billion after income taxes) after deducting the book value of the net assets and certain other adjustments. The Speedway sale gain is accounted for as a discrete item within the discontinued operations income tax provision and includes a current tax provision of $4.16 billion and a deferred income tax benefit of $497 million due to the reversal of MPC’s deferred tax liabilities related to Speedway. The proceeds and related Speedway sale gain may be adjusted in future periods based on provisions of the purchase and sale agreement that allow for adjustments of working capital amounts and other miscellaneous items subsequent to transaction closing date of May 14, 2021. Results of operations for Speedway are reflected through the close of the sale. The following table presents Speedway results and the gain on sale as reported in income from discontinued operations, net of tax, within our consolidated statements of income. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Revenues, other income and net gain on disposal of assets: Revenues and other income $ 3,081 $ 4,147 $ 8,420 $ 9,706 Net gain on disposal of assets 11,682 — 11,682 1 Total revenues, other income and net gain on disposal of assets 14,763 4,147 20,102 9,707 Costs and expenses: Cost of revenues (excludes items below) 2,748 3,524 7,654 8,480 LCM inventory valuation adjustment — (10) — 25 Depreciation and amortization 1 102 3 201 Selling, general and administrative expenses 48 81 121 160 Other taxes 24 44 75 97 Total costs and expenses 2,821 3,741 7,853 8,963 Income from operations 11,942 406 12,249 744 Net interest and other financial costs 2 4 6 10 Income before income taxes 11,940 402 12,243 734 Provision for income taxes 3,726 210 3,795 224 Income from discontinued operations, net of tax $ 8,214 $ 192 $ 8,448 $ 510 Separation Agreements

Master Limited Partnership

Master Limited Partnership	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Master Limited Partnership	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 June 30, 2021, we owned approximately 63 percent of the outstanding MPLX common units. Unit Repurchase Program On November 2, 2020, MPLX announced its board authorized a unit repurchase program for the repurchase of up to $1 billion of MPLX’s outstanding common units held by the public. During the six months ended June 30, 2021, 11,929,998 MPLX common units were repurchased at an average cost per unit of $26.02. Total cash paid for units repurchased during the six months ended June 30, 2021 was $310 million. As of June 30, 2021, MPLX had agreements to acquire 126,293 additional common units for $4 million, which settled in early July 2021. As of June 30, 2021, $657 million remained available under the authorization for future unit repurchases. 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. 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, 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 interests in MPLX were as follows: Six Months Ended (In millions) 2021 2020 Increase (decrease) due to issuance/(repurchase) of MPLX common units $ (76) $ 4 Tax impact 38 (1) Increase (decrease) in MPC's additional paid-in capital, net of tax $ (38) $ 3

Impairments

Impairments	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Impairments	IMPAIRMENTS In the second quarter of 2021, we recognized impairment expense within our Midstream segment related to the anticipated divestiture and closure of certain assets as detailed in the table below. During the first quarter of 2020, the outbreak of COVID-19 caused 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. The table below provides information related to the impairments recognized, along with the location of these impairments within consolidated statement of income. Three Months Ended Six Months Ended (In millions) Income Statement Line 2021 2020 2021 2020 Goodwill Impairment expense $ — $ — $ — $ 7,330 Equity method investments Income (loss) from equity method investments 13 — 13 1,315 Long-lived assets Impairment expense — 25 — 517 Long-lived assets Depreciation and amortization 43 — 43 — Total impairments $ 56 $ 25 $ 56 $ 9,162 Goodwill During the first quarter of 2020, we recorded an impairment of goodwill of $7.33 billion. The $5.516 billion goodwill impairment within the Refining & Marketing segment was primarily driven by the effects of COVID-19 and the decline in commodity prices. The $1.814 billion impairment within the Midstream segment was primarily driven by additional information related to the slowing of drilling activity, which had reduced production growth forecasts from MPLX’s producer customers. 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. 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 was determined based upon applying the discounted cash flow method, an income approach. Long-lived Assets 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. 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.

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [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 24 for more information. The assets of MPLX can only be used to settle their own obligations and their 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) June 30, December 31, Assets Cash and cash equivalents $ 8 $ 15 Receivables, less allowance for doubtful accounts 546 478 Inventories 126 118 Other current assets 46 67 Assets held for sale — 188 Equity method investments 4,033 4,036 Property, plant and equipment, net 20,352 21,418 Goodwill 7,657 7,657 Right of use assets 297 309 Other noncurrent assets 958 1,006 Liabilities Accounts payable $ 495 $ 468 Payroll and benefits payable 6 4 Accrued taxes 83 76 Debt due within one year 1 764 Operating lease liabilities 63 63 Liabilities held for sale — 101 Other current liabilities 298 297 Long-term debt 19,234 19,375 Deferred income taxes 11 12 Long-term operating lease liabilities 232 244 Deferred credits and other liabilities 507 437

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS Transactions with related parties were as follows: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Sales to related parties $ 11 $ 20 $ 54 $ 50 Purchases from related parties 219 158 422 353 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 (Loss) per Share

Earnings (Loss) per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings (Loss) per Share	EARNINGS (LOSS) 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. Three Months Ended Six Months Ended (In millions, except per share data) 2021 2020 2021 2020 Income (loss) from continuing operations, net of tax $ 588 $ 84 $ 418 $ (10,452) Less: Net income (loss) attributable to noncontrolling interest 290 267 596 (717) Net income allocated to participating securities — — — — Income (loss) from continuing operations available to common stockholders 298 (183) (178) (9,735) Income from discontinued operations, net of tax 8,214 192 8,448 510 Income (loss) available to common stockholders $ 8,512 $ 9 $ 8,270 $ (9,225) Weighted average common shares outstanding: Basic 650 650 651 649 Effect of dilutive securities 4 — — — Diluted 654 650 651 649 Income (loss) available to common stockholders per share: Basic: Continuing operations $ 0.46 $ (0.28) $ (0.27) $ (15.00) Discontinued operations 12.63 0.29 12.98 0.79 Net income (loss) per share $ 13.09 $ 0.01 $ 12.71 $ (14.21) Diluted: Continuing operations $ 0.45 $ (0.28) $ (0.27) $ (15.00) Discontinued operations 12.55 0.29 12.98 0.79 Net income (loss) per share $ 13.00 $ 0.01 $ 12.71 $ (14.21) The following table summarizes the shares that were anti-dilutive and, therefore, were excluded from the diluted share calculation. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Shares issuable under stock-based compensation plans 3 9 8 11

Equity

Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Equity	EQUITY In connection with the Speedway sale, our board of directors approved an additional $7.1 billion share repurchase authorization bringing total share repurchase authorizations to $10.0 billion prior to the June tender of shares discussed below. The authorization has no expiration date. 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, if any, will depend upon several factors, including market and business conditions, and such repurchases may be discontinued at any time.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION 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 and to independent entrepreneurs who operate primarily Marathon ® branded outlets, through long-term fuel supply contracts with direct dealers who operate locations mainly under the ARCO ® brand. • 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. Segment income represents income (loss) from operations attributable to the reportable segments. 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. 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. 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: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing $ 224 $ (1,544) $ (374) $ (2,041) Midstream 977 869 1,949 1,774 Segment income (loss) from operations 1,201 (675) 1,575 (267) Corporate (180) (195) (337) (428) Items not allocated to segments: Transaction-related costs (a) — — — (8) Impairments (b) (56) (25) (56) (9,162) LCM inventory valuation adjustment — 1,470 — (1,715) Income (loss) from continuing operations 965 575 1,182 (11,580) Net interest and other financial costs 372 341 725 673 Income (loss) from continuing operations before income taxes $ 593 $ 234 $ 457 $ (12,253) (a) Includes costs incurred in connection with the Midstream strategic review. Costs incurred in connection with the Speedway separation are included in discontinued operations. See Note 4. (b) Includes impairment of goodwill, equity method investments and long lived assets. See Note 6 for additional information. The following reconciles segment depreciation and amortization to total depreciation and amortization as reported in the consolidated statements of income: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing $ 466 $ 463 $ 944 $ 936 Midstream 331 330 665 675 Segment depreciation and amortization 797 793 1,609 1,611 Corporate 74 40 106 85 Total depreciation and amortization $ 871 $ 833 $ 1,715 $ 1,696 The following reconciles segment revenues to sales and other operating revenues as reported in the consolidated statements of income: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing Revenues from external customers (a) $ 28,554 $ 11,387 $ 50,215 $ 32,671 Intersegment revenues 30 4 58 29 Refining & Marketing segment revenues 28,584 11,391 50,273 32,700 Midstream Revenues from external customers (a) 1,061 808 2,111 1,728 Intersegment revenues 1,248 1,165 2,447 2,406 Midstream segment revenues 2,309 1,973 4,558 4,134 Total segment revenues 30,893 13,364 54,831 36,834 Less: intersegment revenues 1,278 1,169 2,505 2,435 Sales and other operating revenues $ 29,615 $ 12,195 $ 52,326 $ 34,399 (a) Includes Refining & Marketing intercompany sales to Speedway prior to May 14, 2021 and related party sales. See Notes 4 and 8 for additional information. The following reconciles segment capital expenditures and investments to total capital expenditures: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing $ 176 $ 271 $ 310 $ 741 Midstream 178 425 316 899 Segment capital expenditures and investments 354 696 626 1,640 Less investments in equity method investees 62 214 113 383 Plus: Corporate 23 18 44 45 Capitalized interest 16 27 30 56 Total capital expenditures (a) $ 331 $ 527 $ 587 $ 1,358 (a) Includes changes in capital expenditure accruals. See Note 21 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2021 and 2020 as reported in the consolidated statements of cash flows.

Net Interest and Other Financia

Net Interest and Other Financial Costs	6 Months Ended
	Jun. 30, 2021
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: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Interest income $ (2) $ (2) $ (3) $ (8) Interest expense 337 371 688 726 Interest capitalized (19) (34) (36) (71) Pension and other postretirement non-service costs (a) 56 (1) 56 (4) Other financial costs — 7 20 30 Net interest and other financial costs $ 372 $ 341 $ 725 $ 673 (a) See Note 23.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES We recorded a combined federal, state and foreign income tax provision of $5 million and $39 million for the three and six months ended June 30, 2021, respectively, which was lower than the tax computed at the U.S. statutory rate primarily due to permanent tax differences related to income attributable to noncontrolling interests. We recorded a combined federal, state and foreign income tax provision of $150 million for the three months ended June 30, 2020, which was higher than the tax computed at the U.S. statutory rate primarily due to impacts attributable to noncontrolling interests, state taxes and the tax rate differential resulting from the expected net operating loss (“NOL”) carryback provided under the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”). We recorded a combined federal, state and foreign income tax benefit of $1,801 million for the six months ended June 30, 2020, which was lower than the tax computed at the U.S. statutory rate primarily due to a significant amount of our pre-tax loss consisting of non-tax deductible goodwill impairment charges, partially offset by the tax rate differential resulting from the expected NOL carryback provided under the CARES Act. Additionally, our non-controlling interest in MPLX generally provides an effective tax rate benefit since the tax associated with those ownership interests is paid by those interests, but this benefit was lower for the six months ended June 30, 2020 due to impairment charges recorded by MPLX. A reconciliation of the continuing operations tax provision (benefit) in dollars as determined using the federal statutory income tax rate applied to income (loss) before income taxes to the provision (benefit) for income taxes is shown in the table below. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Tax computed at statutory rate $ 125 $ 49 $ 96 $ (2,573) State and local income taxes, net of federal income tax effects 13 28 22 (216) Goodwill impairment — — — 1,157 Noncontrolling interests (100) 43 (69) 144 Legislation (a) (23) 18 (17) (325) Unrecognized tax benefits 2 — 16 — Other (12) 12 (9) 12 Total provision (benefit) for income tax from continuing operations $ 5 $ 150 $ 39 $ (1,801) (a) 2020 reflects the impact of the CARES Act. On March 27, 2020, the 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 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 when tax was previously paid in the carryback years. As provided by the NOL carryback statute in the CARES Act, as of June 30, 2021, we have recorded an income tax receivable of $2.1 billion in other current assets. This reflects our estimate of the refund of previously paid tax and we expect to receive nearly all of the refund during the second half of 2021. We are working with the Internal Revenue Service (“IRS”) to facilitate the refund, but we do not control the timing of this payment.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Inventories	INVENTORIES (In millions) June 30, December 31, Crude oil $ 2,780 $ 2,588 Refined products 5,178 4,478 Materials and supplies 921 933 Total $ 8,879 $ 7,999

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT June 30, 2021 December 31, 2020 (In millions) Gross Accumulated Depreciation Net Gross Accumulated Depreciation Net Refining & Marketing $ 30,573 $ 14,086 $ 16,487 $ 30,306 $ 13,257 $ 17,049 Midstream 27,832 6,820 21,012 27,677 6,217 21,460 Corporate 1,389 892 497 1,356 830 526 Total $ 59,794 $ 21,798 $ 37,996 $ 59,339 $ 20,304 $ 39,035

Restructuring

Restructuring	6 Months Ended
	Jun. 30, 2021
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 have settled 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 remaining exit and disposal costs reserve to occur through 2024. (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 Cash payments (32) (16) (48) Restructuring reserve balance at March 31, 2021 $ 6 $ 87 $ 93 Cash payments (5) (11) (16) Restructuring reserve balance at June 30, 2021 $ 1 $ 76 $ 77 (a) The restructuring reserve was zero until the third quarter of 2020.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 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. June 30, 2021 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 $ 340 $ 1 $ — $ (336) $ 5 $ 74 Liabilities: Commodity contracts $ 376 $ 6 $ — $ (382) $ — $ — Embedded derivatives in commodity contracts — — 102 — 102 — 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 — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of June 30, 2021, cash collateral of $46 million was netted with the mark-to-market derivative liabilities. As of December 31, 2020, cash collateral of $11 million was netted with mark-to-market derivative liabilities. (b) We have no derivative contracts that are subject to master netting arrangements reflected gross on the balance sheet. The following is a reconciliation of the beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Beginning balance $ 66 $ 45 $ 63 $ 60 Unrealized and realized (gains) losses included in net income 39 7 45 (7) Settlements of derivative instruments (3) (1) (6) (2) Ending balance $ 102 $ 51 $ 102 $ 51 The amount of total losses (gains) for the period included in earnings attributable to the change in unrealized losses (gains) relating to assets still held at the end of period: $ 39 $ 6 $ 41 $ (7) 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, 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 $27.9 billion and $31.5 billion at June 30, 2021, respectively, and approximately $31.1 billion and $34.9 billion at December 31, 2020, respectively. These carrying and fair values of our debt exclude the unamortized issuance costs which are netted against our total debt.

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [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 17. We do not designate any of our commodity derivative instruments as hedges for accounting purposes. 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. The following table presents the fair value of derivative instruments as of June 30, 2021 and December 31, 2020 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) June 30, 2021 December 31, 2020 Balance Sheet Location Asset Liability Asset Liability Commodity derivatives Other current assets $ 341 $ 382 $ 88 $ 91 Other current liabilities (a) — 14 — 7 Deferred credits and other liabilities (a) — 88 — 56 (a) Includes embedded derivatives. The table below summarizes open commodity derivative contracts for crude oil, refined products and blending products as of June 30, 2021. Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 64.2% 32,507 37,899 Refined products 87.6% 19,615 23,055 Blending products 64.9% 2,624 5,055 Soybean oil 92.8% 1,702 1,838 (a) Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 60 long and 1,460 short; Refined products - 380 long and 210 short; Blending products - 135 short The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income: Gain (Loss) (In millions) Three Months Ended Six Months Ended Income Statement Location 2021 2020 2021 2020 Sales and other operating revenues $ (5) $ (7) $ (15) $ 77 Cost of revenues (168) (105) (233) 26 Total $ (173) $ (112) $ (248) $ 103

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	DEBT Our outstanding borrowings at June 30, 2021 and December 31, 2020 consisted of the following: (In millions) June 30, December 31, Marathon Petroleum Corporation: Commercial paper $ — $ 1,024 Senior notes 8,549 9,849 Notes payable 1 1 Finance lease obligations 602 634 Total $ 9,152 $ 11,508 MPLX LP: Bank revolving credit facility — 175 Senior notes 19,600 20,350 Finance lease obligations 9 11 Total $ 19,609 $ 20,536 Total debt $ 28,761 $ 32,044 Unamortized debt issuance costs (144) (154) Unamortized (discount) premium, net (297) (306) Amounts due within one year (70) (2,854) Total long-term debt due after one year $ 28,250 $ 28,730 Available Capacity under our Credit Facilities as of June 30, 2021 (Dollars in millions) Total Outstanding Outstanding Available Weighted Expiration MPC, excluding MPLX MPC bank revolving credit facility $ 5,000 $ — $ 1 $ 4,999 — % October 2023 MPC trade receivables securitization facility 100 — — 100 — July 2021 MPLX MPLX bank revolving credit facility 3,500 — — 3,500 — % July 2024 MPC 364-Day Bank Revolving Credit Facilities In February 2021, we elected to terminate our $1 billion unsecured 364-day revolving credit facility due in April 2021. 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. Effective June 18, 2021, we terminated our $1 billion unsecured 364-day revolving credit facility due in September 2021. There were no borrowings under this credit facility, and we determined that the incremental borrowing capacity of the facility was no longer necessary. Trade Receivables Securitization Facility On June 23, 2021, we reduced the capacity under our trade receivables securitization facility from $750 million to $100 million as we determined the incremental borrowing capacity of the facility was no longer necessary. This facility expired on July 16, 2021. MPC Senior Notes On March 1, 2021, we repaid the $1 billion outstanding aggregate principal amount of 5.125% senior notes due March 2021. In June 2021, all of the $300 million outstanding aggregate principal amount of 5.125% senior notes due April 2024, including the portion of such notes for which Andeavor was the obligor, were redeemed at a price equal to 100.854% of the principal amount. MPLX Senior Notes On January 15, 2021, MPLX redeemed 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, at a price equal to 102.625% of the principal amount. On August 4, 2021, MPLX announced the intent to provide notice of the redemption of all of the $1 billion outstanding aggregate principal amount of MPLX's LIBOR plus 1.100% per annum floating rate senior notes due September 9, 2022. The notes are expected to be redeemed on September 3, 2021, at a price equal to 100 percent of the principal amount thereof, plus accrued and unpaid interest to, but not including, the redemption date. MPLX expects to fund the redemption amount with a combination of cash on hand and borrowings under the MPLX credit agreement or the MPC intercompany loan agreement.

Revenue

Revenue	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE The following table presents our revenues from external customers disaggregated by segment and product line. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing: Refined products $ 26,528 $ 10,268 $ 46,337 $ 30,537 Crude oil 1,866 1,003 3,312 1,878 Services and other 160 116 566 256 Total revenues from external customers 28,554 11,387 50,215 32,671 Midstream: Refined products 304 123 586 294 Services and other 757 685 1,525 1,434 Total revenues from external customers 1,061 808 2,111 1,728 Sales and other operating revenues $ 29,615 $ 12,195 $ 52,326 $ 34,399 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 June 30, 2021, we do not have future performance obligations that are material to future periods. Receivables On the accompanying consolidated balance sheets, receivables, less allowance for doubtful accounts primarily consists of customer receivables. Significant, non-customer balances included in our receivables at June 30, 2021 include matching buy/sell receivables of $3.84 billion.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION Six Months Ended (In millions) 2021 2020 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 649 $ 601 Net income taxes paid to taxing authorities (a) 319 6 (a) Includes income tax payments related to continuing and discontinued operations. (In millions) June 30, December 31, Cash and cash equivalents (a) $ 11,839 $ 415 Restricted cash (b) — 1 Cash, cash equivalents and restricted cash $ 11,839 $ 416 (a) Excludes $140 million of cash at December 31, 2020, representing Speedway store cash, which was included in assets held for sale. (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: Six Months Ended (In millions) 2021 2020 Additions to property, plant and equipment per the consolidated statements of cash flows $ 606 $ 1,696 Decrease in capital accruals (19) (338) Total capital expenditures $ 587 $ 1,358

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 2021
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, 2019 $ (212) $ (116) $ 1 $ 7 $ (320) Other comprehensive loss before reclassifications, net of tax of $(4) (10) (2) — — (12) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (23) — — — (23) – actuarial loss (a) 18 1 — — 19 – settlement loss (a) 1 — — — 1 Other — — — (3) (3) Tax effect 1 — — 1 2 Other comprehensive loss (13) (1) — (2) (16) Balance as of June 30, 2020 $ (225) $ (117) $ 1 $ 5 $ (336) (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2020 $ (338) $ (181) $ 1 $ 6 $ (512) Other comprehensive gain (loss) before reclassifications, net of tax of $44 132 1 — (4) 129 Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (23) 1 — — (22) – actuarial loss (a) 24 5 — — 29 – settlement loss (a) 49 — — — 49 Tax effect (11) (2) — — (13) Other comprehensive income (loss) 171 5 — (4) 172 Balance as of June 30, 2021 $ (167) $ (176) $ 1 $ 2 $ (340) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 23.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	6 Months Ended
	Jun. 30, 2021
Retirement Benefits [Abstract]
Pension and Other Postretirement Plans	PENSION AND OTHER POSTRETIREMENT BENEFITS The following summarizes the components of net periodic benefit costs: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Pension Benefits Service cost $ 72 $ 77 $ 148 $ 140 Interest cost 23 23 46 48 Expected return on plan assets (29) (31) (62) (65) Amortization – prior service credit (12) (11) (23) (22) – actuarial loss 14 9 25 17 – settlement loss 49 1 49 1 Net periodic pension benefits cost $ 117 $ 68 $ 183 $ 119 Other Benefits Service cost $ 7 $ 9 $ 17 $ 18 Interest cost 8 8 15 16 Amortization – prior service cost — — 1 — – actuarial loss 3 — 5 1 Net periodic other benefits cost $ 18 $ 17 $ 38 $ 35 The components of net periodic benefit cost other than the service cost component are included in net interest and other financial costs on the consolidated statements of income. During the six months ended June 30, 2021, we made contributions of $226 million to our funded pension plans. Benefit payments related to unfunded pension and other postretirement benefit plans were $14 million and $24 million, respectively, during the six months ended June 30, 2021.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
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 both June 30, 2021 and December 31, 2020, accrued liabilities for remediation totaled $397 million. 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 $6 million and $7 million at June 30, 2021 and December 31, 2020, 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. Other Legal Proceedings In early July 2020, Tesoro High Plains Pipeline Company, LLC (“THPP”), a subsidiary of MPLX, received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification 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. THPP appealed this determination, which triggered an automatic stay of the requested pipeline shutdown and payment. On October 29, 2020, 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, 2020 covering all 34 tracts at issue. On December 15, 2020, the Regional Director of the BIA issued a new trespass notice to THPP consistent with the Assistant Secretary - 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 (the “District of North Dakota”) against THPP, the Department of the Interior, the Assistant Secretary - Indian Affairs, the Interior Board of Indian Appeals and the BIA, 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. In March 2021, THPP received a copy of an order purporting to vacate all orders related to THPP’s alleged trespass issued by the BIA between July 2, 2020 and January 14, 2021. The order directs the Regional Director of the BIA to reconsider the issue of THPP’s alleged trespass and issue a new order, if necessary, after all interested parties have had an opportunity to be heard. Subsequently, landowners voluntarily dismissed the suit filed in the District of North Dakota. On April 23, 2021, THPP filed a lawsuit in the District of North Dakota against the United States of America, the U.S. Department of the Interior and the BIA challenging the March order purporting to vacate all previous orders related to THPP’s alleged trespass. 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 tends 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 June 30, 2021. Dakota Access Pipeline In connection with MPLX’s 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, 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. On May 21, 2021, the D.D.C. denied a renewed request for an injunction. On June 22, 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against Dakota Access. The judge noted that the plaintiffs may move to reopen the case in the event of a violation of the court’s prior orders. 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 June 30, 2021, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $230 million. Crowley Ocean Partners LLC and Crowley Blue Water Partners LLC In connection with our 50 percent indirect interest in Crowley Ocean Partners LLC, 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 June 30, 2021, our maximum potential undiscounted payments under this agreement for debt principal totaled $114 million. In connection with our 50 percent indirect interest in Crowley Blue Water Partners LLC, 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 June 30, 2021, our maximum potential undiscounted payments under this arrangement was $111 million. Other guarantees We have entered into other guarantees with maximum potential undiscounted payments totaling $99 million as of June 30, 2021, 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. Contractual Commitments and Contingencies At June 30, 2021, our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $562 million.

Description of the Business a_2

Description of the Business and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Use of estimates	These interim consolidated financial statements are unaudited; however, in the opinion of our management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements.
Short-term investments	Short-Term Investments Investments with a maturity date greater than three months that we intend to convert to cash or cash equivalents within a year or less are classified as short-term investments in our consolidated balance sheets. Additionally, in accordance with ASC 320, Investments - Debt Securities, we have classified all short-term investments as of June 30, 2021 as available-for-sale securities and changes in fair market value are reported in other comprehensive income.
Fair value	Fair Value We account for certain assets and liabilities at fair value. The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. We categorize each of our fair value measurements in one of these three levels based on the lowest level input that is significant to the fair value measurement in its entirety. These levels are: • Level 1 – inputs are based upon unadjusted quoted prices for identical instruments in active markets. Our Level 1 derivative assets and liabilities include 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. • Level 2 – inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs including interest rate curves, credit spreads, and forward and spot prices for currencies. Our Level 2 investments include commercial paper, certificates of deposit, time deposits and corporate notes and bonds. Our Level 2 derivative assets and liabilities primarily include certain OTC contracts. • Level 3 – inputs are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are therefore determined using model-based techniques, including option pricing models and discounted cash flow models. Our Level 3 assets and liabilities include goodwill, long-lived assets and intangible assets, when they are recorded at fair value due to an impairment charge and an 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 June 30, 2021 used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.64 to $1.59 per gallon with a weighted average of $0.81 per gallon and (2) the probability of renewal of 100 percent for the first and second five
Inventories	Inventories are carried at the lower of cost or market value. Costs of crude oil and refined products are aggregated on a consolidated basis for purposes of assessing whether the LIFO cost basis of these inventories may have to be written down to market values.
Derivative instruments	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.

Short-term Investments (Tables)

Short-term Investments (Tables)	6 Months Ended
	Jun. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	The components of investments were as follows: June 30, 2021 (In millions) Fair Value Level Amortized Cost Unrealized Gains Unrealized Losses Fair Value Cash and Cash Equivalents Short-term Investments Available-for-sale debt securities Commercial paper Level 2 $ 8,378 $ — $ — $ 8,378 $ 3,907 $ 4,471 Certificates of deposit and time deposits Level 2 4,501 — — 4,501 3,625 876 U.S. government securities Level 1 50 — — 50 50 — Corporate notes and bonds Level 2 248 — — 248 177 71 Total available-for-sale debt securities $ 13,177 $ — $ — $ 13,177 $ 7,759 $ 5,418 Cash 4,080 4,080 — Total $ 17,257 $ 11,839 $ 5,418

Discontinued Operations (Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2021
Discontinued Operations and Disposal Groups [Abstract]
Condensed Income Statement	Results of operations for Speedway are reflected through the close of the sale. The following table presents Speedway results and the gain on sale as reported in income from discontinued operations, net of tax, within our consolidated statements of income. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Revenues, other income and net gain on disposal of assets: Revenues and other income $ 3,081 $ 4,147 $ 8,420 $ 9,706 Net gain on disposal of assets 11,682 — 11,682 1 Total revenues, other income and net gain on disposal of assets 14,763 4,147 20,102 9,707 Costs and expenses: Cost of revenues (excludes items below) 2,748 3,524 7,654 8,480 LCM inventory valuation adjustment — (10) — 25 Depreciation and amortization 1 102 3 201 Selling, general and administrative expenses 48 81 121 160 Other taxes 24 44 75 97 Total costs and expenses 2,821 3,741 7,853 8,963 Income from operations 11,942 406 12,249 744 Net interest and other financial costs 2 4 6 10 Income before income taxes 11,940 402 12,243 734 Provision for income taxes 3,726 210 3,795 224 Income from discontinued operations, net of tax $ 8,214 $ 192 $ 8,448 $ 510

Master Limited Partnership (Tab

Master Limited Partnership (Tables)	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net	As a result of equity transactions of MPLX, 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 interests in MPLX were as follows: Six Months Ended (In millions) 2021 2020 Increase (decrease) due to issuance/(repurchase) of MPLX common units $ (76) $ 4 Tax impact 38 (1) Increase (decrease) in MPC's additional paid-in capital, net of tax $ (38) $ 3

Impairments (Tables)

Impairments (Tables)	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Details of Impairments	The table below provides information related to the impairments recognized, along with the location of these impairments within consolidated statement of income. Three Months Ended Six Months Ended (In millions) Income Statement Line 2021 2020 2021 2020 Goodwill Impairment expense $ — $ — $ — $ 7,330 Equity method investments Income (loss) from equity method investments 13 — 13 1,315 Long-lived assets Impairment expense — 25 — 517 Long-lived assets Depreciation and amortization 43 — 43 — Total impairments $ 56 $ 25 $ 56 $ 9,162

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities	The following table presents balance sheet information for the assets and liabilities of MPLX, which are included in our balance sheets. (In millions) June 30, December 31, Assets Cash and cash equivalents $ 8 $ 15 Receivables, less allowance for doubtful accounts 546 478 Inventories 126 118 Other current assets 46 67 Assets held for sale — 188 Equity method investments 4,033 4,036 Property, plant and equipment, net 20,352 21,418 Goodwill 7,657 7,657 Right of use assets 297 309 Other noncurrent assets 958 1,006 Liabilities Accounts payable $ 495 $ 468 Payroll and benefits payable 6 4 Accrued taxes 83 76 Debt due within one year 1 764 Operating lease liabilities 63 63 Liabilities held for sale — 101 Other current liabilities 298 297 Long-term debt 19,234 19,375 Deferred income taxes 11 12 Long-term operating lease liabilities 232 244 Deferred credits and other liabilities 507 437

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Transactions with related parties were as follows: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Sales to related parties $ 11 $ 20 $ 54 $ 50 Purchases from related parties 219 158 422 353 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 (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Summary of Earnings Per Common 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. Three Months Ended Six Months Ended (In millions, except per share data) 2021 2020 2021 2020 Income (loss) from continuing operations, net of tax $ 588 $ 84 $ 418 $ (10,452) Less: Net income (loss) attributable to noncontrolling interest 290 267 596 (717) Net income allocated to participating securities — — — — Income (loss) from continuing operations available to common stockholders 298 (183) (178) (9,735) Income from discontinued operations, net of tax 8,214 192 8,448 510 Income (loss) available to common stockholders $ 8,512 $ 9 $ 8,270 $ (9,225) Weighted average common shares outstanding: Basic 650 650 651 649 Effect of dilutive securities 4 — — — Diluted 654 650 651 649 Income (loss) available to common stockholders per share: Basic: Continuing operations $ 0.46 $ (0.28) $ (0.27) $ (15.00) Discontinued operations 12.63 0.29 12.98 0.79 Net income (loss) per share $ 13.09 $ 0.01 $ 12.71 $ (14.21) Diluted: Continuing operations $ 0.45 $ (0.28) $ (0.27) $ (15.00) Discontinued operations 12.55 0.29 12.98 0.79 Net income (loss) per share $ 13.00 $ 0.01 $ 12.71 $ (14.21)
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. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Shares issuable under stock-based compensation plans 3 9 8 11

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
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: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing $ 224 $ (1,544) $ (374) $ (2,041) Midstream 977 869 1,949 1,774 Segment income (loss) from operations 1,201 (675) 1,575 (267) Corporate (180) (195) (337) (428) Items not allocated to segments: Transaction-related costs (a) — — — (8) Impairments (b) (56) (25) (56) (9,162) LCM inventory valuation adjustment — 1,470 — (1,715) Income (loss) from continuing operations 965 575 1,182 (11,580) Net interest and other financial costs 372 341 725 673 Income (loss) from continuing operations before income taxes $ 593 $ 234 $ 457 $ (12,253) (a) Includes costs incurred in connection with the Midstream strategic review. Costs incurred in connection with the Speedway separation are included in discontinued operations. See Note 4.
Reconciliation of Segment Depreciation and Amortization to Total Depreciation and Amortization	The following reconciles segment depreciation and amortization to total depreciation and amortization as reported in the consolidated statements of income: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing $ 466 $ 463 $ 944 $ 936 Midstream 331 330 665 675 Segment depreciation and amortization 797 793 1,609 1,611 Corporate 74 40 106 85 Total depreciation and amortization $ 871 $ 833 $ 1,715 $ 1,696
Reconciliation of Revenue from Segments to Consolidated	The following reconciles segment revenues to sales and other operating revenues as reported in the consolidated statements of income: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing Revenues from external customers (a) $ 28,554 $ 11,387 $ 50,215 $ 32,671 Intersegment revenues 30 4 58 29 Refining & Marketing segment revenues 28,584 11,391 50,273 32,700 Midstream Revenues from external customers (a) 1,061 808 2,111 1,728 Intersegment revenues 1,248 1,165 2,447 2,406 Midstream segment revenues 2,309 1,973 4,558 4,134 Total segment revenues 30,893 13,364 54,831 36,834 Less: intersegment revenues 1,278 1,169 2,505 2,435 Sales and other operating revenues $ 29,615 $ 12,195 $ 52,326 $ 34,399 (a) Includes Refining & Marketing intercompany sales to Speedway prior to May 14, 2021 and related party sales. See Notes 4 and 8 for additional information.
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures	The following reconciles segment capital expenditures and investments to total capital expenditures: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing $ 176 $ 271 $ 310 $ 741 Midstream 178 425 316 899 Segment capital expenditures and investments 354 696 626 1,640 Less investments in equity method investees 62 214 113 383 Plus: Corporate 23 18 44 45 Capitalized interest 16 27 30 56 Total capital expenditures (a) $ 331 $ 527 $ 587 $ 1,358 (a) Includes changes in capital expenditure accruals. See Note 21 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2021 and 2020 as reported in the consolidated statements of cash flows.

Net Interest and Other Financ_2

Net Interest and Other Financial Costs (Tables)	6 Months Ended
	Jun. 30, 2021
Other Income and Expenses [Abstract]
Net Interest And Other Financial Income (Costs)	Net interest and other financial costs were as follows: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Interest income $ (2) $ (2) $ (3) $ (8) Interest expense 337 371 688 726 Interest capitalized (19) (34) (36) (71) Pension and other postretirement non-service costs (a) 56 (1) 56 (4) Other financial costs — 7 20 30 Net interest and other financial costs $ 372 $ 341 $ 725 $ 673 (a) See Note 23.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the continuing operations tax provision (benefit) in dollars as determined using the federal statutory income tax rate applied to income (loss) before income taxes to the provision (benefit) for income taxes is shown in the table below. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Tax computed at statutory rate $ 125 $ 49 $ 96 $ (2,573) State and local income taxes, net of federal income tax effects 13 28 22 (216) Goodwill impairment — — — 1,157 Noncontrolling interests (100) 43 (69) 144 Legislation (a) (23) 18 (17) (325) Unrecognized tax benefits 2 — 16 — Other (12) 12 (9) 12 Total provision (benefit) for income tax from continuing operations $ 5 $ 150 $ 39 $ (1,801) (a) 2020 reflects the impact of the CARES Act.

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Summary Of Inventories	(In millions) June 30, December 31, Crude oil $ 2,780 $ 2,588 Refined products 5,178 4,478 Materials and supplies 921 933 Total $ 8,879 $ 7,999

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Summary Of Property, Plant And Equipment	June 30, 2021 December 31, 2020 (In millions) Gross Accumulated Depreciation Net Gross Accumulated Depreciation Net Refining & Marketing $ 30,573 $ 14,086 $ 16,487 $ 30,306 $ 13,257 $ 17,049 Midstream 27,832 6,820 21,012 27,677 6,217 21,460 Corporate 1,389 892 497 1,356 830 526 Total $ 59,794 $ 21,798 $ 37,996 $ 59,339 $ 20,304 $ 39,035

Restructuring (Tables)

Restructuring (Tables)	6 Months Ended
	Jun. 30, 2021
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 Cash payments (32) (16) (48) Restructuring reserve balance at March 31, 2021 $ 6 $ 87 $ 93 Cash payments (5) (11) (16) Restructuring reserve balance at June 30, 2021 $ 1 $ 76 $ 77 (a) The restructuring reserve was zero until the third quarter of 2020.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021 and December 31, 2020 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. June 30, 2021 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 $ 340 $ 1 $ — $ (336) $ 5 $ 74 Liabilities: Commodity contracts $ 376 $ 6 $ — $ (382) $ — $ — Embedded derivatives in commodity contracts — — 102 — 102 — 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 — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of June 30, 2021, cash collateral of $46 million was netted with the mark-to-market derivative liabilities. As of December 31, 2020, cash collateral of $11 million was netted with mark-to-market derivative liabilities. (b) We have no derivative contracts that 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. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Beginning balance $ 66 $ 45 $ 63 $ 60 Unrealized and realized (gains) losses included in net income 39 7 45 (7) Settlements of derivative instruments (3) (1) (6) (2) Ending balance $ 102 $ 51 $ 102 $ 51 The amount of total losses (gains) for the period included in earnings attributable to the change in unrealized losses (gains) relating to assets still held at the end of period: $ 39 $ 6 $ 41 $ (7)

Derivatives (Tables)

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Classification of Fair Values of Derivative Instruments, Excluding Cash Collateral	The following table presents the fair value of derivative instruments as of June 30, 2021 and December 31, 2020 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) June 30, 2021 December 31, 2020 Balance Sheet Location Asset Liability Asset Liability Commodity derivatives Other current assets $ 341 $ 382 $ 88 $ 91 Other current liabilities (a) — 14 — 7 Deferred credits and other liabilities (a) — 88 — 56 (a) Includes embedded derivatives.
Open Commodity Derivative Contracts	The table below summarizes open commodity derivative contracts for crude oil, refined products and blending products as of June 30, 2021. Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 64.2% 32,507 37,899 Refined products 87.6% 19,615 23,055 Blending products 64.9% 2,624 5,055 Soybean oil 92.8% 1,702 1,838 (a) Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 60 long and 1,460 short; Refined products - 380 long and 210 short; Blending products - 135 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: Gain (Loss) (In millions) Three Months Ended Six Months Ended Income Statement Location 2021 2020 2021 2020 Sales and other operating revenues $ (5) $ (7) $ (15) $ 77 Cost of revenues (168) (105) (233) 26 Total $ (173) $ (112) $ (248) $ 103

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Outstanding Borrowings	Our outstanding borrowings at June 30, 2021 and December 31, 2020 consisted of the following: (In millions) June 30, December 31, Marathon Petroleum Corporation: Commercial paper $ — $ 1,024 Senior notes 8,549 9,849 Notes payable 1 1 Finance lease obligations 602 634 Total $ 9,152 $ 11,508 MPLX LP: Bank revolving credit facility — 175 Senior notes 19,600 20,350 Finance lease obligations 9 11 Total $ 19,609 $ 20,536 Total debt $ 28,761 $ 32,044 Unamortized debt issuance costs (144) (154) Unamortized (discount) premium, net (297) (306) Amounts due within one year (70) (2,854) Total long-term debt due after one year $ 28,250 $ 28,730
Schedule of Line of Credit Facilities	Available Capacity under our Credit Facilities as of June 30, 2021 (Dollars in millions) Total Outstanding Outstanding Available Weighted Expiration MPC, excluding MPLX MPC bank revolving credit facility $ 5,000 $ — $ 1 $ 4,999 — % October 2023 MPC trade receivables securitization facility 100 — — 100 — July 2021 MPLX MPLX bank revolving credit facility 3,500 — — 3,500 — % July 2024

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue from External Customers by Products and Services	The following table presents our revenues from external customers disaggregated by segment and product line. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Refining & Marketing: Refined products $ 26,528 $ 10,268 $ 46,337 $ 30,537 Crude oil 1,866 1,003 3,312 1,878 Services and other 160 116 566 256 Total revenues from external customers 28,554 11,387 50,215 32,671 Midstream: Refined products 304 123 586 294 Services and other 757 685 1,525 1,434 Total revenues from external customers 1,061 808 2,111 1,728 Sales and other operating revenues $ 29,615 $ 12,195 $ 52,326 $ 34,399

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information	Six Months Ended (In millions) 2021 2020 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 649 $ 601 Net income taxes paid to taxing authorities (a) 319 6 (a) Includes income tax payments related to continuing and discontinued operations.
Schedule of Cash and Cash Equivalents	(In millions) June 30, December 31, Cash and cash equivalents (a) $ 11,839 $ 415 Restricted cash (b) — 1 Cash, cash equivalents and restricted cash $ 11,839 $ 416 (a) Excludes $140 million of cash at December 31, 2020, representing Speedway store cash, which was included in assets held for sale. (b) The restricted cash balance is included within other current assets on the consolidated balance sheets.
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: Six Months Ended (In millions) 2021 2020 Additions to property, plant and equipment per the consolidated statements of cash flows $ 606 $ 1,696 Decrease in capital accruals (19) (338) Total capital expenditures $ 587 $ 1,358

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2021
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, 2019 $ (212) $ (116) $ 1 $ 7 $ (320) Other comprehensive loss before reclassifications, net of tax of $(4) (10) (2) — — (12) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (23) — — — (23) – actuarial loss (a) 18 1 — — 19 – settlement loss (a) 1 — — — 1 Other — — — (3) (3) Tax effect 1 — — 1 2 Other comprehensive loss (13) (1) — (2) (16) Balance as of June 30, 2020 $ (225) $ (117) $ 1 $ 5 $ (336) (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2020 $ (338) $ (181) $ 1 $ 6 $ (512) Other comprehensive gain (loss) before reclassifications, net of tax of $44 132 1 — (4) 129 Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (23) 1 — — (22) – actuarial loss (a) 24 5 — — 29 – settlement loss (a) 49 — — — 49 Tax effect (11) (2) — — (13) Other comprehensive income (loss) 171 5 — (4) 172 Balance as of June 30, 2021 $ (167) $ (176) $ 1 $ 2 $ (340) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 23.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	6 Months Ended
	Jun. 30, 2021
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Costs	The following summarizes the components of net periodic benefit costs: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Pension Benefits Service cost $ 72 $ 77 $ 148 $ 140 Interest cost 23 23 46 48 Expected return on plan assets (29) (31) (62) (65) Amortization – prior service credit (12) (11) (23) (22) – actuarial loss 14 9 25 17 – settlement loss 49 1 49 1 Net periodic pension benefits cost $ 117 $ 68 $ 183 $ 119 Other Benefits Service cost $ 7 $ 9 $ 17 $ 18 Interest cost 8 8 15 16 Amortization – prior service cost — — 1 — – actuarial loss 3 — 5 1 Net periodic other benefits cost $ 18 $ 17 $ 38 $ 35

Description of the Business a_3

Description of the Business and Basis of Presentation (Fair Value) (Details)	6 Months Ended
	Jun. 30, 2021$ / galUSD ($)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Average forward price | $ / gal	0.81
Embedded derivatives in commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Term of contract	5 years
Embedded derivatives in commodity contracts | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Probability of renewal first term	100.00%
Probability of renewal second term	100.00%
Minimum | Commodity derivatives | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	0.64
Maximum | Commodity derivatives | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	1.59

Short-term Investments (Compone

Short-term Investments (Components of Investments) (Details) $ in Millions	Jun. 30, 2021USD ($)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 13,177
Unrealized Gains	0
Unrealized Losses	0
Fair Value	13,177
Cash	4,080
Short-term investments and cash	17,257
Commercial paper | Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,378
Unrealized Gains	0
Unrealized Losses	0
Fair Value	8,378
Certificates of deposit and time deposits | Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,501
Unrealized Gains	0
Unrealized Losses	0
Fair Value	4,501
U.S. government securities | Level 1
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	50
Unrealized Gains	0
Unrealized Losses	0
Fair Value	50
Corporate notes and bonds | Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	248
Unrealized Gains	0
Unrealized Losses	0
Fair Value	248
Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Fair Value	7,759
Cash	4,080
Short-term investments and cash	11,839
Cash and Cash Equivalents | Commercial paper | Level 2
Debt Securities, Available-for-sale [Line Items]
Fair Value	3,907
Cash and Cash Equivalents | Certificates of deposit and time deposits | Level 2
Debt Securities, Available-for-sale [Line Items]
Fair Value	3,625
Cash and Cash Equivalents | U.S. government securities | Level 1
Debt Securities, Available-for-sale [Line Items]
Fair Value	50
Cash and Cash Equivalents | Corporate notes and bonds | Level 2
Debt Securities, Available-for-sale [Line Items]
Fair Value	177
Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Fair Value	5,418
Cash	0
Short-term investments and cash	5,418
Short-term Investments | Commercial paper | Level 2
Debt Securities, Available-for-sale [Line Items]
Fair Value	4,471
Short-term Investments | Certificates of deposit and time deposits | Level 2
Debt Securities, Available-for-sale [Line Items]
Fair Value	876
Short-term Investments | U.S. government securities | Level 1
Debt Securities, Available-for-sale [Line Items]
Fair Value	0
Short-term Investments | Corporate notes and bonds | Level 2
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 71

Discontinued Operations (Detail

Discontinued Operations (Details) - Speedway - Discontinued Operations, Disposed of by Sale $ in Millions	May 14, 2021USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from sale of Speedway	$ 21,380
Proceeds from the sale of Speedway, net of tax	17,220
Gain from disposal of discontinued operation, before income tax	11,680
Gain on disposal of discontinued operation, net of tax	8,020
Current income tax expense on gain from disposal of discontinued operation	4,160
Deferred income tax benefit on gain from disposal of discontinued operation	$ 497

Discontinued Operations (Result

Discontinued Operations (Results of Operations associated with Discontinued Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues, other income and net gain on disposal of assets:
Net gain on disposal of assets	$ 0	$ 2	$ 3	$ 5
Total revenues, other income and net gain on disposal of assets	29,827	12,300	52,709	33,297
Costs and expenses:
Cost of revenues (excludes items below)	27,177	11,502	48,261	31,844
LCM inventory valuation adjustment	0	(1,470)	0	1,715
Depreciation and amortization	871	833	1,715	1,696
Selling, general and administrative expenses	625	665	1,200	1,407
Other taxes	189	170	351	368
Total costs and expenses	28,862	11,725	51,527	44,877
Income from operations	965	575	1,182	(11,580)
Net interest and other financial costs	372	341	725	673
Income from discontinued operations, net of tax	8,214	192	8,448	510
Discontinued Operations, Disposed of by Sale
Revenues, other income and net gain on disposal of assets:
Revenues and other income	3,081	4,147	8,420	9,706
Net gain on disposal of assets	11,682	0	11,682	1
Total revenues, other income and net gain on disposal of assets	14,763	4,147	20,102	9,707
Costs and expenses:
Cost of revenues (excludes items below)	2,748	3,524	7,654	8,480
LCM inventory valuation adjustment	0	(10)	0	25
Depreciation and amortization	1	102	3	201
Selling, general and administrative expenses	48	81	121	160
Other taxes	24	44	75	97
Total costs and expenses	2,821	3,741	7,853	8,963
Income from operations	11,942	406	12,249	744
Net interest and other financial costs	2	4	6	10
Income before income taxes	11,940	402	12,243	734
Provision for income taxes	3,726	210	3,795	224
Income from discontinued operations, net of tax	$ 8,214	$ 192	$ 8,448	$ 510

Master Limited Partnership (Det

Master Limited Partnership (Details)	Jun. 30, 2021
MPLX | Marathon Petroleum Corporation
MPC's partnership interest in MLP (in percentage)	63.00%

Master Limited Partnership (Uni

Master Limited Partnership (Unit Repurchase Program) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	6 Months Ended
	Jul. 31, 2021	Jun. 30, 2021	Nov. 02, 2020
Stock repurchase program, authorized amount		$ 10,000
Stock repurchase program, remaining authorized repurchase amount		$ 9,020
MPLX LP
Stock repurchase program, authorized amount			$ 1,000
Stock repurchased and retired during period, shares		11,929,998
Treasury stock acquired, average cost per share		$ 26.02
Stock repurchased and retired during period, value		$ 310
Stock repurchase program, remaining authorized repurchase amount		$ 657
MPLX LP | Subsequent Event
Stock repurchased and retired during period, shares	126,293
Stock repurchased and retired during period, value	$ 4

Master Limited Partnership (Non

Master Limited Partnership (Noncontrolling Interest) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Equity transactions of MPLX	$ (148)	$ (124)	$ 6	$ (7)
Additional Paid-in Capital
Increase (decrease) due to issuance/(repurchase) of MPLX common units					$ (76)	$ 4
Tax impact					38	(1)
Equity transactions of MPLX	$ (34)	$ (4)	$ 8	$ (5)	$ (38)	$ 3

Impairments (Income Statement L

Impairments (Income Statement Location of Impairments) (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment			$ 7,330
Equity method investment impairment			$ 1,315
Total impairments	$ 56	$ 25		$ 56	$ 9,162
Impairment expense
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	0	0		0	7,330
Long-lived assets impairment	0	25		0	517
Income (loss) from equity method investments
Finite-Lived Intangible Assets [Line Items]
Equity method investment impairment	13	0		13	1,315
Depreciation and amortization
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment	$ 43	$ 0		$ 43	$ 0

Impairments (Goodwill) (Details

Impairments (Goodwill) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 7,330
Refining & Marketing
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	5,516
Midstream
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 1,814

Impairments (Equity Method Inve

Impairments (Equity Method Investments) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Finite-Lived Intangible Assets [Line Items]
Equity method investment impairment	$ 1,315
MPLX LP | MarkWest Utica EMG
Finite-Lived Intangible Assets [Line Items]
Equity method investment impairment	$ 1,250

Impairments (Long-lived Assets)

Impairments (Long-lived Assets) (Details) - Impairment expense - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment	$ 0	$ 25		$ 0	$ 517
Refining & Marketing
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment			$ 142
MPLX LP | Midstream
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment			$ 350

Variable Interest Entities (Con

Variable Interest Entities (Consolidated VIEs) (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents	[1]	$ 11,839	$ 415
Receivables, less allowance for doubtful accounts		9,771	5,760
Inventories		8,879	7,999
Other current assets		2,685	2,724
Equity method investments		5,424	5,422
Property, plant and equipment, net		37,996	39,035
Goodwill		8,256	8,256
Right of use assets		1,500	1,521
Other noncurrent assets		2,532	2,637
Liabilities
Accounts payable		12,170	7,803
Payroll and benefits payable		651	732
Accrued taxes		5,219	1,105
Debt due within one year		70	2,854
Operating lease liabilities		473	497
Other current liabilities		929	822
Long-term debt		28,250	28,730
Deferred income taxes		5,704	6,203
Long-term operating lease liabilities		1,020	1,014
Deferred credits and other liabilities		1,271	1,207
Variable Interest Entity, Primary Beneficiary | MPLX
Assets
Cash and cash equivalents		8	15
Receivables, less allowance for doubtful accounts		546	478
Inventories		126	118
Other current assets		46	67
Assets held for sale		0	188
Equity method investments		4,033	4,036
Property, plant and equipment, net		20,352	21,418
Goodwill		7,657	7,657
Right of use assets		297	309
Other noncurrent assets		958	1,006
Liabilities
Accounts payable		495	468
Payroll and benefits payable		6	4
Accrued taxes		83	76
Debt due within one year		1	764
Operating lease liabilities		63	63
Liabilities held for sale		0	101
Other current liabilities		298	297
Long-term debt		19,234	19,375
Deferred income taxes		11	12
Long-term operating lease liabilities		232	244
Deferred credits and other liabilities		$ 507	$ 437
[1]	Excludes $140 million of cash at December 31, 2020, representing Speedway store cash, which was included in assets held for sale.

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transactions [Abstract]
Sales to related parties	$ 11	$ 20	$ 54	$ 50
Purchases from related parties	$ 219	$ 158	$ 422	$ 353

Earnings (Loss) Per Share (Summ

Earnings (Loss) Per Share (Summary of Earnings (Loss) Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Income (loss) from continuing operations, net of tax	$ 588	$ 84	$ 418	$ (10,452)
Less: Net income (loss) attributable to noncontrolling interest	290	267	596	(717)
Net income allocated to participating securities	0	0	0	0
Income (loss) from continuing operations available to common stockholders	298	(183)	(178)	(9,735)
Income from discontinued operations, net of tax	8,214	192	8,448	510
Income (loss) available to common stockholders	$ 8,512	$ 9	$ 8,270	$ (9,225)
Weighted average common shares outstanding:
Basic (in shares)	650	650	651	649
Effect of dilutive securities (in shares)	4	0	0	0
Diluted (in shares)	654	650	651	649
Basic:
Continuing operations	$ 0.46	$ (0.28)	$ (0.27)	$ (15)
Discontinued operations	12.63	0.29	12.98	0.79
Net income (loss) per share	13.09	0.01	12.71	(14.21)
Diluted:
Continuing operations	0.45	(0.28)	(0.27)	(15)
Discontinued operations	12.55	0.29	12.98	0.79
Net income (loss) per share	$ 13	$ 0.01	$ 12.71	$ (14.21)

Earnings (Loss) Per Share (Anti

Earnings (Loss) Per Share (Anti-dilutive Shares) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock Based Compensation Expense
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable under stock-based compensation plans	3	9	8	11

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 15, 2021	Jun. 30, 2021	Jun. 30, 2020
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount		$ 10,000
Payments for repurchase of common stock		984	$ 0
Stock repurchase program, remaining authorized repurchase amount		9,020
Share Repurchase Authorization May 2021
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount		$ 7,100
Modified Dutch Auction Tender
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased	15,573,365
Treasury stock acquired, average cost per share	$ 63
Payments for repurchase of common stock	$ 981

Segment Information (Additional

Segment Information (Additional Information) (Detail)	6 Months Ended
	Jun. 30, 2021Segment
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information (Reconcilia

Segment Information (Reconciliation Of Segment Income From Operations To Income Before Income Taxes) (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021		Jun. 30, 2020		Jun. 30, 2021	Jun. 30, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) from operations	$ 965		$ 575		$ 1,182	$ (11,580)
Impairments	56		25		56	9,162
LCM inventory valuation adjustment	0		(1,470)		0	1,715
Net interest and other financial costs	372		341		725	673
Income before income taxes	593		234		457	(12,253)
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) from operations	1,201		(675)		1,575	(267)
Operating Segments | Refining & Marketing
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) from operations	224		(1,544)		(374)	(2,041)
Operating Segments | Midstream
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) from operations	977		869		1,949	1,774
Corporate
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income (loss) from operations	(180)		(195)		(337)	(428)
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Transaction-related costs	0	[1]	0	[1]	0	(8)	[1]
Impairments	(56)	[2]	(25)		(56)	(9,162)	[2]
LCM inventory valuation adjustment	$ 0		$ 1,470		$ 0	$ (1,715)
[1]	Includes costs incurred in connection with the Midstream strategic review. Costs incurred in connection with the Speedway separation are included in discontinued operations. See Note 4.
[2]	Includes impairment of goodwill, equity method investments and long lived assets. See Note 6 for additional information.

Segment Information (Reconcil_2

Segment Information (Reconciliation of Segment D&A to Total D&A) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	$ 871	$ 833	$ 1,715	$ 1,696
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	797	793	1,609	1,611
Operating Segments | Refining & Marketing
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	466	463	944	936
Operating Segments | Midstream
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	331	330	665	675
Corporate
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	$ 74	$ 40	$ 106	$ 85

Segment Information (Reconcil_3

Segment Information (Reconciliation of Segment Revenues To Sales and Other Operating Revenues) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Sales and other operating revenues		$ 29,615	$ 12,195	$ 52,326	$ 34,399
Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues	[1]	28,554	11,387	50,215	32,671
Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues	[1]	1,061	808	2,111	1,728
Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		1,278	1,169	2,505	2,435
Intersegment Eliminations | Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues		30	4	58	29
Intersegment Eliminations | Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues		1,248	1,165	2,447	2,406
Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		30,893	13,364	54,831	36,834
Operating Segments | Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues		28,584	11,391	50,273	32,700
Operating Segments | Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues		$ 2,309	$ 1,973	$ 4,558	$ 4,134
[1]	Includes Refining & Marketing intercompany sales to Speedway prior to May 14, 2021 and related party sales. See Notes 4 and 8 for additional information

Segment Information (Reconcil_4

Segment Information (Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Plus:
Capital expenditures	[1]	$ 331	$ 527	$ 587	$ 1,358
Operating Segments
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments		354	696	626	1,640
Less investments in equity method investees		62	214	113	383
Operating Segments | Refining & Marketing
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments		176	271	310	741
Operating Segments | Midstream
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments		178	425	316	899
Corporate
Plus:
Corporate		23	18	44	45
Capitalized interest		$ 16	$ 27	$ 30	$ 56
[1]	Includes changes in capital expenditure accruals. See Note 21 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2021 and 2020 as reported in the consolidated statements of cash flows.

Net Interest and Other Financ_3

Net Interest and Other Financial Costs (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Other Income and Expenses [Abstract]
Interest income		$ (2)	$ (2)	$ (3)	$ (8)
Interest expense		337	371	688	726
Interest capitalized		(19)	(34)	(36)	(71)
Pension and other postretirement non-service costs	[1]	56	(1)	56	(4)
Other financial costs		0	7	20	30
Net interest and other financial costs		$ 372	$ 341	$ 725	$ 673
[1]	See Note 23.

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Provision (benefit) for income taxes on continuing operations	$ 5	$ 150	$ 39	$ (1,801)
CARES Act
Income taxes receivable, current	$ 2,100		$ 2,100

Income Taxes (Tax Rate Reconcil

Income Taxes (Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Tax computed at statutory rate	$ 125	$ 49	$ 96	$ (2,573)
State and local income taxes, net of federal income tax effects	13	28	22	(216)
Goodwill impairment	0	0	0	1,157
Noncontrolling interests	(100)	43	(69)	144
Legislation	(23)	18	(17)	(325)	[1]
Unrecognized tax benefits	2	0	16	0
Other	(12)	12	(9)	12
Provision (benefit) for income taxes on continuing operations	$ 5	$ 150	$ 39	$ (1,801)
[1]	2020 reflects the impact of the CARES Act.

Inventories (Summary of Invento

Inventories (Summary of Inventories) (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Crude oil	$ 2,780	$ 2,588
Refined products	5,178	4,478
Materials and supplies	921	933
Inventories	$ 8,879	$ 7,999

Property, Plant and Equipment_2

Property, Plant and Equipment (Summary of Property, Plant And Equipment) (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 59,794	$ 59,339
Less accumulated depreciation	21,798	20,304
Property, plant and equipment, net	37,996	39,035
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	30,573	30,306
Less accumulated depreciation	14,086	13,257
Property, plant and equipment, net	16,487	17,049
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	27,832	27,677
Less accumulated depreciation	6,820	6,217
Property, plant and equipment, net	21,012	21,460
Corporate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,389	1,356
Less accumulated depreciation	892	830
Property, plant and equipment, net	$ 497	$ 526

Restructuring (Details)

Restructuring (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Sep. 30, 2020USD ($)	[1]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 367
Restructuring reserve	$ 141	$ 77	$ 93	$ 291
Number of positions eliminated	2,050
Exit and disposal costs
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 195
Restructuring reserve	103	76	87	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	130
Employee separation costs
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	172
Restructuring reserve	38	$ 1	$ 6	$ 158
MPLX LP | Employee separation costs
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) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring reserve - beginning balance	$ 93	$ 141	$ 291	[1]
Adjustments			19
Cash payments	(16)	(48)	(169)
Restructuring reserve - ending balance	77	93	141
Employee separation costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve - beginning balance	6	38	158	[1]
Adjustments			14
Cash payments	(5)	(32)	(134)
Restructuring reserve - ending balance	1	6	38
Exit and disposal costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve - beginning balance	87	103	133	[1]
Adjustments			5
Cash payments	(11)	(16)	(35)
Restructuring reserve - ending balance	$ 76	$ 87	$ 103
[1]	The restructuring reserve was zero until the third quarter of 2020.

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Accounted for at Fair Value on Recurring Basis) (Detail) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash collateral netted with derivative liabilities		$ 46	$ 11
Fair Value, Measurements, Recurring | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - netting and collateral	[1]	(336)	(80)
Commodity derivative instruments, assets - net carrying value on balance sheet	[2]	5	8
Commodity derivative instruments, assets - collateral pledged not offset		74	31
Commodity derivative instruments, liabilities - netting and collateral	[1]	(382)	(91)
Commodity derivative instruments, liabilities - net carrying value on balance sheet	[2]	0	0
Commodity derivative instruments, liabilities - collateral pledged not offset		0	0
Fair Value, Measurements, Recurring | Embedded derivatives 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 carrying value on balance sheet	[2]	102	63
Commodity derivative instruments, liabilities - collateral pledged not offset		0	0
Fair Value, Measurements, Recurring | Level 1 | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset		340	82
Commodity derivative instruments, liabilities - gross		376	81
Fair Value, Measurements, Recurring | Level 1 | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		0	0
Fair Value, Measurements, Recurring | Level 2 | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset		1	6
Commodity derivative instruments, liabilities - gross		6	10
Fair Value, Measurements, Recurring | Level 2 | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		0	0
Fair Value, Measurements, Recurring | Level 3 | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset		0	0
Commodity derivative instruments, liabilities - gross		0	0
Fair Value, Measurements, Recurring | Level 3 | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		$ 102	$ 63
[1]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of June 30, 2021, cash collateral of $46 million was netted with the mark-to-market derivative liabilities. As of December 31, 2020, cash collateral of $11 million was netted with mark-to-market derivative liabilities.
[2]	We have no derivative contracts that are subject to master netting arrangements reflected gross on the balance sheet.

Fair Value Measurements (Reconc

Fair Value Measurements (Reconciliation of Net Beginning and Ending Balances Recorded for Net Assets and Liabilities Classified as Level 3) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 66	$ 45	$ 63	$ 60
Unrealized and realized (gains) losses included in net income	39	7	45	(7)
Settlements of derivative instruments	(3)	(1)	(6)	(2)
Ending balance	$ 102	$ 51	$ 102	$ 51

Fair Value Measurements (Losses

Fair Value Measurements (Losses Included in Earnings Relating to Assets Still Held at End of Period) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair Value Disclosures [Abstract]
The amount of total losses (gains) for the period included in earnings attributable to the change in unrealized losses (gains) relating to assets still held at the end of period:	$ 39	$ 6	$ 41	$ (7)

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Values - Reported) (Detail) - USD ($) $ in Billions	Jun. 30, 2021	Dec. 31, 2020
Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 27.9	$ 31.1
Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 31.5	$ 34.9

Derivatives (Classification of

Derivatives (Classification of Gross Fair Values of Derivative Instruments, Excluding Cash Collateral) (Detail) - Commodity derivatives - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Other current assets
Derivative [Line Items]
Asset		$ 341	$ 88
Liability		382	91
Other current liabilities
Derivative [Line Items]
Asset		0	0
Liability	[1]	14	7
Deferred credits and other liabilities
Derivative [Line Items]
Asset		0	0
Liability	[1]	$ 88	$ 56
[1]	Includes embedded derivatives.

Derivatives (Open Commodity Der

Derivatives (Open Commodity Derivative Contracts) (Details) - Exchange Traded gal in Thousands, bbl in Thousands	6 Months Ended
	Jun. 30, 2021bblgal
Crude oil
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	64.20%
Crude oil | Long
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	32,507
Crude oil | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	60
Crude oil | Short
Derivative [Line Items]
Notional contracts (in thousands of total barrels) | gal	37,899
Crude oil | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	1,460
Refined products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	87.60%
Refined products | Long
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	19,615
Refined products | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	380
Refined products | Short
Derivative [Line Items]
Notional contracts (in thousands of total barrels) | gal	23,055
Refined products | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	210
Blending products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	64.90%
Blending products | Long
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	2,624
Blending products | Short
Derivative [Line Items]
Notional contracts (in thousands of total barrels) | gal	5,055
Blending products | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	135
Soybean oil
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	92.80%
Soybean oil | Long
Derivative [Line Items]
Notional contracts (in thousands of total barrels)	1,702
Soybean oil | Short
Derivative [Line Items]
Notional contracts (in thousands of total barrels) | gal	1,838

Derivatives (Effect of Commodit

Derivatives (Effect of Commodity Derivative Instruments in Statements of Income) (Detail) - Commodity derivatives - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (173)	$ (112)	$ (248)	$ 103
Sales and other operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	(5)	(7)	(15)	77
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (168)	$ (105)	$ (233)	$ 26

Debt (Outstanding Borrowings) (

Debt (Outstanding Borrowings) (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Total debt	$ 28,761	$ 32,044
Unamortized debt issuance costs	(144)	(154)
Unamortized (discount) premium, net	(297)	(306)
Amounts due within one year	(70)	(2,854)
Total long-term debt due after one year	28,250	28,730
Marathon Petroleum Corporation:
Finance lease obligations	602	634
Total debt	9,152	11,508
Marathon Petroleum Corporation: | Commercial paper
Long-term debt, gross	0	1,024
Marathon Petroleum Corporation: | Senior notes
Long-term debt, gross	8,549	9,849
Marathon Petroleum Corporation: | Notes payable
Long-term debt, gross	1	1
MPLX LP:
Finance lease obligations	9	11
Total debt	19,609	20,536
MPLX LP: | Bank revolving credit facility
Long-term debt, gross	0	175
MPLX LP: | Senior notes
Long-term debt, gross	$ 19,600	$ 20,350

Debt (Available Capacity under

Debt (Available Capacity under our Facilities) (Details) $ in Millions	Jun. 30, 2021USD ($)
MPC bank revolving credit facility
Debt Instrument [Line Items]
Total Capacity	$ 5,000
Outstanding Borrowings	0
Outstanding Letters of Credit	1
Available Capacity	$ 4,999
Weighted Average Interest Rate	0.00%
MPC trade receivables securitization facility
Debt Instrument [Line Items]
Total Capacity	$ 100
Outstanding Borrowings	0
Outstanding Letters of Credit	0
Available Capacity	$ 100
Weighted Average Interest Rate	0.00%
MPLX LP | MPLX bank revolving credit facility
Debt Instrument [Line Items]
Total Capacity	$ 3,500
Outstanding Borrowings	0
Outstanding Letters of Credit	0
Available Capacity	$ 3,500
Weighted Average Interest Rate	0.00%

Debt (MPC 364-Day Bank Revolvin

Debt (MPC 364-Day Bank Revolving Credit Facilities) (Details) - Marathon Petroleum Corporation: - USD ($) $ in Millions	Jun. 18, 2021	Feb. 28, 2021
MPC 364-day bank revolving credit facility due April 2021
Debt Instrument [Line Items]
Line of credit facility, termination		$ 1,000
MPC 364-day revolving credit facility due September 2021
Debt Instrument [Line Items]
Line of credit facility, termination	$ 1,000

Debt (Trade Receivables Securit

Debt (Trade Receivables Securitization Facility) (Details) - USD ($) $ in Millions	Jun. 23, 2021	Jul. 19, 2019
MPC trade receivables securitization facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 100	$ 750

Debt (MPC Senior Notes) (Detail

Debt (MPC Senior Notes) (Details) - Marathon Petroleum Corporation: - Senior notes - USD ($) $ in Millions	Mar. 01, 2021	Jun. 30, 2021
Senior notes, 5.125% due March 2021
Debt Instrument [Line Items]
Repayments of debt	$ 1,000
Senior notes, 5.125% due April 2024
Debt Instrument [Line Items]
Repayments of debt		$ 300

Debt (MPLX Senior Notes) (Detai

Debt (MPLX Senior Notes) (Details) - MPLX LP - Senior notes - USD ($) $ in Millions	Sep. 03, 2021	Jan. 15, 2021
Senior notes, 5.250% due January 2025
Debt Instrument [Line Items]
Repayments of debt		$ 750
Floating rate senior notes due September 2022 | Subsequent Event
Debt Instrument [Line Items]
Repayments of debt	$ 1,000

Revenue (Disaggregated by Produ

Revenue (Disaggregated by Product Line) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Sales and other operating revenues		$ 29,615	$ 12,195	$ 52,326	$ 34,399
Refining & Marketing
Sales and other operating revenues	[1]	28,554	11,387	50,215	32,671
Refining & Marketing | Refined products
Sales and other operating revenues		26,528	10,268	46,337	30,537
Refining & Marketing | Crude oil
Sales and other operating revenues		1,866	1,003	3,312	1,878
Refining & Marketing | Services and other
Sales and other operating revenues		160	116	566	256
Midstream
Sales and other operating revenues	[1]	1,061	808	2,111	1,728
Midstream | Refined products
Sales and other operating revenues		304	123	586	294
Midstream | Services and other
Sales and other operating revenues		$ 757	$ 685	$ 1,525	$ 1,434
[1]	Includes Refining & Marketing intercompany sales to Speedway prior to May 14, 2021 and related party sales. See Notes 4 and 8 for additional information

Revenue (Details)

Revenue (Details) $ in Millions	Jun. 30, 2021USD ($)
Revenue from Contract with Customer [Abstract]
Matching buy/sell receivables	$ 3,840

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Summary of Supplemental Cash Flow Information) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021		Jun. 30, 2020
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 649		$ 601
Net income taxes paid to (received from) taxing authorities	$ 319	[1]	$ 6
[1]	Includes income tax payments related to continuing and discontinued operations.

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information (Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Cash and cash equivalents	[1]	$ 11,839	$ 415
Restricted cash	[2]	0	1
Cash, cash equivalents and restricted cash		11,839	416	$ 966	$ 1,395
Discontinued Operations, Held-for-sale
Cash and cash equivalents			140
Cash, cash equivalents and restricted cash	[3]	$ 0	$ 140	$ 127	$ 134
[1]	Excludes $140 million of cash at December 31, 2020, representing Speedway store cash, which was included in assets held for sale.
[2]	The restricted cash balance is included within other current assets on the consolidated balance sheets
[3]	Reported as assets held for sale on our consolidated balance sheets.

Supplemental Cash Flow Inform_5

Supplemental Cash Flow Information (Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Additions to property, plant and equipment per the consolidated statements of cash flows				$ 606	$ 1,696
Decrease in capital accruals				(19)	(338)
Capital expenditures	[1]	$ 331	$ 527	$ 587	$ 1,358
[1]	Includes changes in capital expenditure accruals. See Note 21 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2021 and 2020 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) (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ (512)		$ (320)	$ (512)	$ (320)
Other comprehensive income (loss), before reclassifications, net of tax						129	(12)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit						(22)	(23)
Amortization - actuarial loss						29	19
Amortization - settlement loss						49	1
Other							(3)
Tax effect						(13)	2
Other comprehensive income (loss)		$ 171	1	$ (10)	(6)	172	(16)
Ending balance		(340)		(336)		(340)	(336)
Other comprehensive income (loss) before reclassifications, tax						44	(4)
Accumulated Defined Benefit Plans Adjustment | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(338)		(212)	(338)	(212)
Other comprehensive income (loss), before reclassifications, net of tax						132	(10)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]					(23)	(23)
Amortization - actuarial loss	[1]					24	18
Amortization - settlement loss	[1]					49	1
Tax effect						(11)	1
Other comprehensive income (loss)						171	(13)
Ending balance		(167)		(225)		(167)	(225)
Accumulated Defined Benefit Plans Adjustment | Other Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(181)		(116)	(181)	(116)
Other comprehensive income (loss), before reclassifications, net of tax						1	(2)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]					1	0
Amortization - actuarial loss	[1]					5	1
Amortization - settlement loss						0	0
Tax effect						(2)	0
Other comprehensive income (loss)						5	(1)
Ending balance		(176)		(117)		(176)	(117)
Gain on Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			1		1	1	1
Other comprehensive income (loss), before reclassifications, net of tax						0	0
Amounts reclassified from accumulated other comprehensive loss:
Tax effect						0	0
Other comprehensive income (loss)						0	0
Ending balance		1		1		1	1
Workers Compensation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ 6		$ 7	6	7
Other comprehensive income (loss), before reclassifications, net of tax						(4)	0
Amounts reclassified from accumulated other comprehensive loss:
Other							(3)
Tax effect						0	1
Other comprehensive income (loss)						(4)	(2)
Ending balance		$ 2		$ 5		$ 2	$ 5
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 23.

Pension and Other Postretirem_3

Pension and Other Postretirement Benefits (Components of Net Periodic Benefit Costs) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 72	$ 77	$ 148	$ 140
Interest cost	23	23	46	48
Expected return on plan assets	(29)	(31)	(62)	(65)
Amortization – prior service credit	(12)	(11)	(23)	(22)
Amortization – actuarial loss	14	9	25	17
Amortization - settlement loss	49	1	49	1
Net periodic benefit cost	117	68	183	119
Other Benefits
Components of net periodic benefit cost:
Service cost	7	9	17	18
Interest cost	8	8	15	16
Amortization – prior service credit	0	0	1	0
Amortization – actuarial loss	3	0	5	1
Net periodic benefit cost	$ 18	$ 17	$ 38	$ 35

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits (Additional Information) (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 226
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	14
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	$ 24

Commitments and Contingencies (

Commitments and Contingencies (Detail)	6 Months Ended
	Jun. 30, 2021
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	Jun. 30, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Accrued liabilities for remediation	$ 397	$ 397
Receivables for recoverable costs	$ 6	$ 7

Commitments and Contingencies_3

Commitments and Contingencies (Other Legal Proceedings) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jul. 31, 2020	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Loss contingency, damages sought, value	$ 187
Loss contingency, damages paid, value		$ 4

Commitments and Contingencies_4

Commitments and Contingencies (Guarantees) (Details) $ in Millions	Jun. 30, 2021USD ($)
Other Guarantees
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 99
LOOP and LOCAP LLC | Guarantee of Indebtedness of Others | Financial Guarantee
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 171
Bakken Pipeline System
Loss Contingencies [Line Items]
Ownership percentage	9.19%
Bakken Pipeline System | Guarantee of Indebtedness of Others | Financial Guarantee
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 230
Crowley Ocean Partners
Loss Contingencies [Line Items]
Ownership percentage	50.00%
Crowley Ocean Partners | Guarantee of Indebtedness of Others | Financial Guarantee
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 114
Crowley Ocean Partners | Guarantee of Indebtedness of Others | Financial Guarantee | Crowley Term Loan
Loss Contingencies [Line Items]
Maximum borrowing capacity	$ 325
Crowley Blue Water Partners
Loss Contingencies [Line Items]
Ownership percentage	50.00%
Crowley Blue Water Partners | Guarantee of Indebtedness of Others | Financial Guarantee
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 111

Commitments and Contingencies_5

Commitments and Contingencies (Contractual Commitments and Contingencies) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	$ 562