Marathon Petroleum (MPC) 10-Q 3 Aug 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Jul. 30, 2020
Cover [Abstract]
Entity Central Index Key	0001510295
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q2
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-35054
Entity Registrant Name	Marathon Petroleum Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-1284632
Entity Address, Address Line One	539 South Main Street
Entity Address, City or Town	Findlay
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45840-3229
City Area Code	419
Local Phone Number	422-2121
Title of 12(b) Security	Common Stock, par value $.01
Trading Symbol	MPC
Security Exchange Name	NYSE
Entity 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		650,695,467

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020		Jun. 30, 2019
Revenues and other income:
Sales and other operating revenues	$ 15,024	$ 33,529	$ 40,239		$ 61,782
Income (loss) from equity method investments	105	107	(1,105)	[1],[2]	206
Net gain on disposal of assets	2	4	6		218
Other income	67	30	138		65
Total revenues and other income	15,198	33,670	39,278		62,271
Costs and expenses:
Cost of revenues (excludes items below)	13,777	29,682	36,598		55,642
LCM inventory valuation adjustment	(1,480)	0	1,740		0
Impairment expense	25	0	7,847		0
Depreciation and amortization	935	886	1,897		1,805
Selling, general and administrative expenses	746	886	1,567		1,753
Other taxes	214	174	465		360
Total costs and expenses	14,217	31,628	50,114		59,560
Income (loss) from operations	981	2,042	(10,836)		2,711
Net interest and other financial costs	345	322	683		628
Income (loss) before income taxes	636	1,720	(11,519)		2,083
Provision (benefit) for income taxes	360	353	(1,577)		457
Net income (loss)	276	1,367	(9,942)		1,626
Less net income (loss) attributable to:
Redeemable noncontrolling interest	21	21	41		41
Noncontrolling interests	246	240	(758)		486
Net income (loss) attributable to MPC	$ 9	$ 1,106	$ (9,225)		$ 1,099
Basic:
Net income (loss) attributable to MPC per share	$ 0.01	$ 1.67	$ (14.21)		$ 1.65
Weighted average shares outstanding (in shares)	650	662	649		667
Diluted:
Net income (loss) attributable to MPC per share	$ 0.01	$ 1.66	$ (14.21)		$ 1.63
Weighted average shares outstanding (in shares)	653	666	649		672
[1]	The six months ended June 30, 2020 includes $1,315 million of impairment expense. See Note 4 for further information.
[2]	The six months ended June 30, 2020 includes $1,315 million of impairment expense. See Note 4

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net income (loss)	$ 276	$ 1,367	$ (9,942)	$ 1,626
Other comprehensive loss	(10)	(10)	(16)	(17)
Comprehensive income (loss)	266	1,357	(9,958)	1,609
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	21	21	41	41
Noncontrolling interests	246	240	(758)	486
Comprehensive income (loss) attributable to MPC	(1)	1,096	(9,241)	1,082
Actuarial changes, net of tax of $0, $0, $1 and $6, respectively
Other comprehensive loss	(1)	(1)	3	(4)
Prior service, net of tax of ($3), ($3), ($6) and ($11), respectively
Other comprehensive loss	(8)	(8)	(17)	(11)
Other, net of tax of ($1), ($1), ($1) and ($1), respectively
Other comprehensive loss	$ (1)	$ (1)	$ (2)	$ (2)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Actuarial changes
OCI, tax expense (benefit)	$ 0	$ 0	$ 1	$ 6
Prior service
OCI, tax expense (benefit)	(3)	(3)	(6)	(11)
Other
OCI, tax expense (benefit)	$ (1)	$ (1)	$ (1)	$ (1)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 1,091	$ 1,527
Receivables, less allowance for doubtful accounts of $18 and $17, respectively	4,361	7,479
Inventories	8,086	10,243
Other current assets	1,105	921
Total current assets	14,643	20,170
Equity method investments	5,740	6,898
Property, plant and equipment, net	45,025	45,615
Goodwill	12,710	20,040
Right of use assets	2,454	2,459
Other noncurrent assets	4,021	3,374
Total assets	84,593	98,556
Current liabilities:
Accounts payable	6,110	11,623
Payroll and benefits payable	815	1,126
Accrued taxes	1,272	1,186
Debt due within one year	1,715	711
Operating lease liabilities	625	604
Other current liabilities	967	897
Total current liabilities	11,504	16,147
Long-term debt	30,451	28,127
Deferred income taxes	5,914	6,392
Defined benefit postretirement plan obligations	1,772	1,643
Long-term operating lease liabilities	1,850	1,875
Deferred credits and other liabilities	1,285	1,265
Total liabilities	52,776	55,449
Commitments and contingencies (see Note 22)
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 – 979 million and 978 million shares (par value $0.01 per share, 2 billion shares authorized)	10	10
Held in treasury, at cost – 329 million and 329 million shares	(15,149)	(15,143)
Additional paid-in capital	33,208	33,157
Retained earnings	6,008	15,990
Accumulated other comprehensive loss	(336)	(320)
Total MPC stockholders’ equity	23,741	33,694
Noncontrolling interests	7,108	8,445
Total equity	30,849	42,139
Total liabilities, redeemable noncontrolling interest and equity	$ 84,593	$ 98,556

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 18	$ 17
Preferred stock:
Shares issued	0	0
Shares outstanding	0	0
Par value	$ 0.01
Shares authorized	30
Common stock:
Shares issued	979	978
Par value	$ 0.01
Shares authorized	2,000
Treasury stock	(329)	(329)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019
Operating activities:
Net income (loss)	$ (9,942)		$ 1,626
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization of deferred financing costs and debt discount	30		9
Impairment expense	7,847		0
Depreciation and amortization	1,897		1,805
LCM inventory valuation adjustment	1,740		0
Pension and other postretirement benefits, net	103		86
Deferred income taxes	(465)		360
Net gain on disposal of assets	(6)		(218)
(Income) loss from equity method investments	1,105	[1],[2]	(206)
Distributions from equity method investments	330		310
Changes in income tax receivable	(1,150)		(106)
Changes in the fair value of derivative instruments	23		(27)
Changes in operating assets and liabilities, net of effects of businesses acquired:
Current receivables	3,117		(1,697)
Inventories	417		740
Current accounts payable and accrued liabilities	(5,220)		1,297
Right of use assets and operating lease liabilities, net	2		9
All other, net	(58)		257
Net cash provided by (used in) operating activities	(230)		4,245
Investing activities:
Additions to property, plant and equipment	(1,910)		(2,419)
Disposal of assets	79		33
Investments – acquisitions, loans and contributions	(383)		(595)
Investments - redemptions, repayments and return of capital	118		58
All other, net	19		43
Net cash used in investing activities	(2,077)		(2,880)
Financing activities:
Long-term debt – borrowings	9,672		7,964
Long-term debt – repayments	(6,388)		(7,116)
Debt issuance costs	(24)		0
Issuance of common stock	6		3
Common stock repurchased	0		(1,385)
Dividends paid	(755)		(706)
Distributions to noncontrolling interests	(620)		(640)
Contributions from noncontrolling interests	0		95
All other, net	(20)		(56)
Net cash provided by (used in) financing activities	1,871		(1,841)
Net change in cash, cash equivalents and restricted cash	(436)		(476)
Cash, cash equivalents and restricted cash at beginning of period	1,529		1,725
Cash, cash equivalents and restricted cash at end of period	$ 1,093		$ 1,249
[1]	The six months ended June 30, 2020 includes $1,315 million of impairment expense. See Note 4 for further information.
[2]	The six months ended June 30, 2020 includes $1,315 million of impairment expense. See Note 4

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 Loss	Non-controlling Interests
Beginning balance at Dec. 31, 2018	$ 44,049	$ 10	$ (13,175)	$ 33,729	$ 14,755	$ (144)	$ 8,874
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	239				(7)		246
Dividends declared on common stock	(357)				(357)
Distributions to noncontrolling interests	(305)						(305)
Contributions from noncontrolling interests	95						95
Other comprehensive loss	(7)					(7)
Shares repurchased	(885)		(885)
Shares returned - stock based compensation			(3)
Shares issued - stock based compensation				32
Net shares issued - stock based compensation	28						(1)
Equity transactions of MPLX & ANDX	2			3			(1)
Other	(1)						(1)
Ending balance at Mar. 31, 2019	42,858	10	(14,063)	33,764	14,391	(151)	8,907
Beginning balance at Dec. 31, 2018	44,049	10	(13,175)	33,729	14,755	(144)	8,874
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss	(17)
Equity transactions of MPLX & ANDX				5
Ending balance at Jun. 30, 2019	43,061	10	(14,573)	33,785	15,146	(161)	8,854
Beginning balance at Mar. 31, 2019	42,858	10	(14,063)	33,764	14,391	(151)	8,907
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,346				1,106		240
Dividends declared on common stock	(351)				(351)
Distributions to noncontrolling interests	(295)						(295)
Other comprehensive loss	(10)					(10)
Shares repurchased	(500)		(500)
Shares returned - stock based compensation			(10)
Shares issued - stock based compensation				19
Net shares issued - stock based compensation	11						2
Equity transactions of MPLX & ANDX	1			2			(1)
Other	1						1
Ending balance at Jun. 30, 2019	43,061	10	(14,573)	33,785	15,146	(161)	8,854
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 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 & ANDX	(7)			(5)			(2)
Other	1				1
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 loss	(16)
Equity transactions of MPLX & ANDX				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 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 & ANDX	6			8			(2)
Other	(1)				(1)
Ending balance at Jun. 30, 2020	$ 30,849	$ 10	$ (15,149)	$ 33,208	$ 6,008	$ (336)	$ 7,108

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, 2018		975
Number of common shares issued - stock compensation		1
Ending balance at Mar. 31, 2019		976
Number of common shares issued - stock compensation		2
Ending balance at Jun. 30, 2019		978
Beginning balance at Dec. 31, 2019	978	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	979

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, 2018		(295)
Number of shares repurchased		(14)
Number of shares returned - stock compensation		0
Ending balance at Mar. 31, 2019		(309)
Beginning balance at Dec. 31, 2018		(295)
Number of shares repurchased	(23)
Ending balance at Jun. 30, 2019		(318)
Beginning balance at Mar. 31, 2019		(309)
Number of shares repurchased	(9)	(9)
Number of shares returned - stock compensation		0
Ending balance at Jun. 30, 2019		(318)
Beginning balance at Dec. 31, 2019	(329)	(329)
Number of shares returned - stock compensation		0
Ending balance at Mar. 31, 2020		(329)
Beginning balance at Dec. 31, 2019	(329)	(329)
Number of shares repurchased	0
Ending balance at Jun. 30, 2020	(329)	(329)
Beginning balance at Mar. 31, 2020		(329)
Number of shares repurchased	0
Number of shares returned - stock compensation		0
Ending balance at Jun. 30, 2020	(329)	(329)

Consolidated Statements of Eq_4

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Redeemable Noncontrolling Interest) - USD ($) $ in Millions	Total	Redeemable Noncontrolling Interest
Beginning balance at Dec. 31, 2018		$ 1,004
Net income attributable to redeemable noncontrolling interest		20
Distributions to noncontrolling interests		(20)
Ending balance at Mar. 31, 2019		1,004
Beginning balance at Dec. 31, 2018		1,004
Net income attributable to redeemable noncontrolling interest	$ 41
Ending balance at Jun. 30, 2019		1,005
Beginning balance at Mar. 31, 2019		1,004
Net income attributable to redeemable noncontrolling interest	21	21
Distributions to noncontrolling interests		(20)
Ending balance at Jun. 30, 2019		$ 1,005
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
Distributions to noncontrolling interests	(21)
Ending balance at Jun. 30, 2020	$ 968

Consolidated Statements of Eq_5

Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Dividends declared per share of common stock (in dollars per share)	$ 0.58	$ 0.58	$ 0.53	$ 0.53

Description of the Business and

Description of the Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business and Basis of Presentation	DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION Description of the Business We are a leading, integrated, downstream energy company headquartered in Findlay, Ohio. We operate the nation's largest refining system. We sell refined products to wholesale marketing customers domestically and internationally, to buyers on the spot market, to consumers through our Retail business segment and to independent entrepreneurs who operate approximately 7,000 branded outlets. Our retail operations own and operate approximately 3,870 retail transportation fuel and convenience stores across the United States and also sell transportation fuel to consumers through approximately 1,070 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. See Note 23 Subsequent Events for information regarding the announced agreement to sell our Speedway business. Basis of Presentation All significant intercompany transactions and accounts have been eliminated. Certain prior period financial statement amounts have been reclassified to conform to current period presentation. 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, 2019 . The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results to be expected for the full year.

Accounting Standards

Accounting Standards	6 Months Ended
	Jun. 30, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recently Adopted	ACCOUNTING STANDARDS Recently Adopted Effective January 1, 2020, we adopted ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” using the modified retrospective transition method. The amendment requires entities to consider a broader range of information to estimate expected credit losses, which may result in earlier recognition of losses. The ASU requires the company to utilize an expected loss methodology in place of the incurred loss methodology for financial instruments, including trade receivables, and off-balance sheet credit exposures. Adoption of the standard did not have a material impact on our financial statements. We are exposed to credit losses primarily through our sales of refined petroleum products, crude oil and midstream services. We assess each customer’s ability to pay through our credit review process. The credit review process considers various factors such as external credit ratings, a review of financial statements to determine liquidity, leverage, trends and business specific risks, market information, pay history and our business strategy. Customers that do not qualify for payment terms are required to prepay or provide a letter of credit. We monitor our ongoing credit exposure through timely review of customer payment activity. At June 30, 2020 , we reported $4,361 million of accounts and notes receivable, net of allowances of $18 million . We are also exposed to credit losses from off-balance sheet exposures, such as guarantees of joint venture debt. See Note 22 for more information on these off-balance sheet exposures. We also adopted the following ASUs during the first six months of 2020, which also did not have a material impact to our financial statements or financial statement disclosures: ASU Effective Date 2018-13 Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement January 1, 2020 2020-04 Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting April 1, 2020
Not Yet Adopted	Not Yet Adopted ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes

Master Limited Partnership

Master Limited Partnership	6 Months Ended
	Jun. 30, 2020
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, 2020 we owned approximately 63 percent of the outstanding MPLX common units. MPLX’s Acquisition of ANDX On July 30, 2019, MPLX completed its acquisition of Andeavor Logistics LP (“ANDX”), and ANDX survived as a wholly owned subsidiary of MPLX. At the effective time of the ANDX acquisition, each common unit held by ANDX’s public unitholders was converted into the right to receive 1.135 MPLX common units. ANDX common units held by MPC were converted into the right to receive 1.0328 MPLX common units. Additionally, as a result of MPLX’s acquisition of ANDX, 600,000 ANDX preferred units were converted into 600,000 preferred units of MPLX (“Series B preferred units”). Series B preferred unitholders are entitled to receive, when and if declared by the board, a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three month LIBOR plus 4.652 percent. MPC accounted for this transaction as a common control transaction, as defined by ASC 805, which resulted in an increase to noncontrolling interest and a decrease to additional paid-in capital of approximately $55 million , net of tax. During the third quarter of 2019, we pushed down to MPLX the portion of the goodwill attributable to ANDX as of October 1, 2018, the date of our acquisition of Andeavor. Due to this push down of goodwill, we also recorded an incremental $642 million deferred tax liability associated with the portion of the non-deductible goodwill attributable to the noncontrolling interest in MPLX with an offsetting reduction of our additional paid-in capital balance. We have consolidated ANDX since we acquired Andeavor on October 1, 2018 in accordance with ASC 810. Agreements We have various long-term, fee-based commercial agreements with MPLX. Under these agreements, MPLX provides transportation, storage, distribution and marketing services to us. With certain exceptions, these agreements generally contain minimum volume commitments. These transactions are eliminated in consolidation but are reflected as intersegment transactions between our Refining & Marketing and Midstream segments. We also have agreements with MPLX that establish fees for operational and management services provided between us and MPLX and for executive management services and certain general and administrative services provided by us to MPLX. These transactions are eliminated in consolidation but are reflected as intersegment transactions between our Corporate and Midstream segments. Noncontrolling Interest As a result of equity transactions of MPLX and ANDX, we are required to adjust non-controlling interest and additional paid-in capital. Changes in MPC’s additional paid-in capital resulting from changes in its ownership interests in MPLX and ANDX were as follows: Six Months Ended (In millions) 2020 2019 Increase due to the issuance of MPLX & ANDX common units $ 4 $ 7 Tax impact (1 ) (2 ) Increase in MPC's additional paid-in capital, net of tax $ 3 $ 5

Impairments

Impairments	6 Months Ended
	Jun. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Impairments	IMPAIRMENTS The outbreak of COVID-19 and its development into a pandemic in March 2020 have resulted in significant economic disruption globally. Actions taken by various governmental authorities, individuals and companies around the world to prevent the spread of COVID-19 through social distancing have restricted travel, many business operations, public gatherings and the overall level of individual movement and in-person interaction across the globe. This has in turn significantly reduced global economic activity and resulted in a decrease in motor vehicle use at a time when seasonal driving patterns typically result in an increase of consumer demand for gasoline and a dramatic reduction in airline flights. These macroeconomic conditions and certain global geopolitical events in the first quarter of 2020 contributed to a significant decline in crude oil prices as well as an increase in crude oil price volatility. The decrease in demand for refined petroleum products coupled with the decline in the price of crude oil has resulted in a significant decrease in the price and volume of the refined petroleum products we produce and sell as compared to the three and six months ended June 30, 2019 . During the first quarter of 2020, the overall deterioration in the economy and the environment in which we operate, the related changes to our expected future cash flows, as well as a sustained decrease in share price were considered triggering events requiring various impairment assessments of the carrying values of our assets, which resulted in the impairment charges discussed below. The table below provides information related to the impairments recognized during the three and six months ended June 30, 2020 and the location of these impairments within the consolidated statements of income. Three Months Ended Six Months Ended (In millions) Income Statement Line 2020 2020 Goodwill Impairment expense $ — $ 7,330 Equity method investments Income (loss) from equity method investments — 1,315 Long-lived assets Impairment expense (a) 25 517 Total impairments $ 25 $ 9,162 (a) Impairment expense in the three months ended June 30, 2020 is related to a Midstream terminal asset with remaining net book value of $10 million . Goodwill During the first quarter of 2020, we recorded an impairment of goodwill of $7.33 billion . See the table below for detail by segment. The goodwill impairment within the Refining & Marketing segment was primarily driven by the effects of COVID-19 and the decline in commodity prices. The impairment within the Midstream segment was primarily driven by additional information related to the slowing of drilling activity, which has reduced production growth forecasts from MPLX’s producer customers. The fair value of the reporting units for the goodwill impairment analysis was determined based on applying both a discounted cash flow or income approach as well as a market approach. The discounted cash flow fair value estimate is based on known or knowable information at the measurement date. The significant assumptions that were used to develop the estimates of the fair values under the discounted cash flow method included management’s best estimates of the expected future results and discount rates, which range from 9.0 percent to 13.5 percent . Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the interim goodwill impairment test will prove to be an accurate prediction of the future. The fair value measurements for the individual reporting units’ overall fair values represent Level 3 measurements. The changes in carrying amount of goodwill were as follows: (In millions) Refining & Marketing Retail Midstream Total Balance at January 1, 2020 $ 5,572 $ 4,951 $ 9,517 $ 20,040 Impairments (5,516 ) — (1,814 ) (7,330 ) Transfers (56 ) — 56 — Balance at June 30, 2020 $ — $ 4,951 $ 7,759 $ 12,710 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 joint ventures. The fair value of the investments was determined based upon applying the discounted cash flow method, which is an income approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future cash flows, including prices and volumes, the weighted average cost of capital and the long-term growth rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment test will prove to be an accurate prediction of the future. The fair value of these equity method investments represents a Level 3 measurement. Long-lived Assets Long-lived assets used in operations are assessed for impairment whenever changes in facts and circumstances indicate that the carrying value of the assets may not be recoverable based on the expected undiscounted future cash flow of an asset group. For purposes of impairment evaluation, long-lived assets must be grouped at the lowest level for which independent cash flows can be identified, which generally is the refinery and associated distribution system level for Refining & Marketing segment assets, company-owned convenience store locations for Retail segment assets and the plant level or pipeline system level for Midstream segment assets. If the sum of the undiscounted estimated pretax cash flows is less than the carrying value of an asset group, fair value is calculated, and the carrying value is written down to the calculated fair value. During the first quarter of 2020, we identified long-lived asset impairment triggers relating to all 16 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 assessed each refinery asset group for impairment by comparing the undiscounted estimated pretax cash flows to the carrying value of each asset group. Of the 16 refinery asset groups, only the Gallup refinery’s carrying value exceeded its undiscounted estimated pretax cash flows. It was determined that the fair value of the Gallup refinery’s property, plant and equipment was less than the carrying value. As a result, we recorded a charge of $142 million in the first quarter of 2020 to impairment expense on the consolidated statements of income. The fair value measurements for the Gallup refinery assets represent Level 3 measurements. During the second quarter of 2020, we identified long-lived asset impairment triggers relating to all of our refinery asset groups within the Refining & Marketing segment, except the Gallup refinery which had been impaired in the first quarter, as a result of continued macroeconomic developments impacting the Refining & Marketing segment expected future cash flows. All of these refinery asset group’s undiscounted estimated pretax cash flows exceeded their carrying value by at least 17 percent . The determination of undiscounted estimated pretax cash flows utilized significant assumptions including management’s best estimates of the expected future cash flows, allocation of certain Refining & Marketing segment cash flows to the individual refineries, the estimated useful lives of the asset groups, and the salvage values of the refineries. On August 3, 2020, we announced our plans to evaluate possibilities to strategically reposition our Martinez refinery, including the potential conversion of the refinery into a renewable diesel facility. The outcome of our evaluation could result in an impairment triggering event and significantly change the assumptions and results of a future impairment test for the refinery’s long-lived assets. The determinations of expected future cash flows and the salvage values of refineries require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of our impairment analysis will prove to be an accurate prediction of the future. Should our assumptions significantly change in future periods, it is possible we may determine the carrying values of certain of our refinery asset groups exceed the undiscounted estimated pretax cash flows of their refinery asset groups, which would result in future impairment charges. During the first quarter of 2020, we identified an impairment trigger relating to asset groups within MPLX’s Western G&P reporting unit as a result of significant changes to expected future cash flows for these asset groups resulting from the effects of COVID-19. The cash flows associated with these assets were significantly impacted by volume declines reflecting decreased forecasted producer customer production as a result of lower commodity prices. We assessed each asset group within the Western G&P reporting unit for impairment. It was determined that the fair value of the East Texas G&P asset group’s underlying assets were less than the carrying value. As a result, MPLX recorded impairment charges totaling $350 million related to its property, plant and equipment and intangibles, which are included in impairment expense on our consolidated statements of income. Fair value of property, plant and equipment was determined using a combination of an income and cost approach. The income approach utilized significant assumptions including management’s best estimates of the expected future cash flows and the estimated useful life of the asset group. The cost approach utilized assumptions for the current replacement costs of similar assets adjusted for estimated depreciation and deterioration of the existing equipment and economic obsolescence. The fair value of the intangibles was determined based on applying the multi-period excess earnings method, which is an income approach. Key assumptions included management’s best estimates of the expected future cash flows from existing customers, customer attrition rates and the discount rate. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the impairment analysis will prove to be an accurate prediction of the future. The fair value measurements for the asset group fair values represent Level 3 measurements.

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2020
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 substantive 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 22 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 $ 67 $ 15 Receivables, less allowance for doubtful accounts 567 615 Inventories 115 110 Other current assets 49 110 Equity method investments 4,065 5,275 Property, plant and equipment, net 21,958 22,174 Goodwill 7,722 9,536 Right of use assets 341 365 Other noncurrent assets 1,074 1,323 Liabilities Accounts payable $ 471 $ 744 Payroll and benefits payable 2 5 Accrued taxes 83 80 Debt due within one year 3 9 Operating lease liabilities 69 66 Other current liabilities 265 259 Long-term debt 20,556 19,704 Deferred income taxes 11 12 Long-term operating lease liabilities 274 302 Deferred credits and other liabilities 442 409

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2020
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) 2020 2019 2020 2019 Sales to related parties $ 106 $ 186 $ 271 $ 372 Purchases from related parties 158 183 353 387 Sales to related parties, which are included in sales and other operating revenues, consist primarily of sales of refined products to PFJ Southeast, an equity affiliate which owns and operates travel plazas primarily in the Southeast region of the United States.

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Loss per Share	EARNINGS PER SHARE We compute basic earnings (loss) per share by dividing net income (loss) attributable to MPC less income allocated to participating securities by the weighted average number of shares of common stock outstanding. Since MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities, we have calculated our earnings (loss) per share using the two-class method. Diluted income (loss) per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive. Three Months Ended Six Months Ended (In millions, except per share data) 2020 2019 2020 2019 Basic Allocation of earnings: Net income (loss) attributable to MPC $ 9 $ 1,106 $ (9,225 ) $ 1,099 Income allocated to participating securities — — — 1 Income (loss) available to common stockholders – basic $ 9 $ 1,106 $ (9,225 ) $ 1,098 Weighted average common shares outstanding 650 662 649 667 Basic earnings (loss) per share $ 0.01 $ 1.67 $ (14.21 ) $ 1.65 Diluted Allocation of earnings: Net income (loss) attributable to MPC $ 9 $ 1,106 $ (9,225 ) $ 1,099 Income allocated to participating securities — — — 1 Income (loss) available to common stockholders – diluted $ 9 $ 1,106 $ (9,225 ) $ 1,098 Weighted average common shares outstanding 650 662 649 667 Effect of dilutive securities 3 4 — 5 Weighted average common shares, including dilutive effect 653 666 649 672 Diluted earnings (loss) per share $ 0.01 $ 1.66 $ (14.21 ) $ 1.63 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) 2020 2019 2020 2019 Shares issuable under stock-based compensation plans 9 4 11 3

Equity

Equity	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Equity	EQUITY As of June 30, 2020 , we had $2.96 billion of remaining share repurchase authorizations from our board of directors. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, tender offers, accelerated share repurchases or open market solicitations for shares, some of which may be effected through Rule 10b5-1 plans. The timing and amount of future repurchases, if any, will depend upon several factors, including market and business conditions, and such repurchases may be discontinued at any time. Total share repurchases were as follows for the respective periods: Three Months Ended Six Months Ended (In millions, except per share data) 2020 2019 2020 2019 Number of shares repurchased — 9 — 23 Cash paid for shares repurchased $ — $ 500 $ — $ 1,385 Average cost per share $ — $ 57.18 $ — $ 60.75

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION We have three reportable segments: Refining & Marketing, Retail and Midstream. Each of these segments is organized and managed based upon the nature of the products and services it offers. • Refining & Marketing – refines crude oil and other feedstocks at our refineries in the Gulf Coast, Mid-Continent and West Coast regions of the United States, purchases refined products and ethanol for resale and distributes refined products through transportation, storage, distribution and marketing services provided largely by our Midstream segment. We sell refined products to wholesale marketing customers domestically and internationally, to buyers on the spot market, to our Retail business segment and to independent entrepreneurs who operate primarily Marathon ® branded outlets. • Retail – sells transportation fuels and convenience products in the retail market across the United States through company-owned and operated convenience stores, primarily under the Speedway ® brand, and 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 administrative expenses, except for those attributable to MPLX, and costs related to certain non-operating assets are not allocated to the Refining & Marketing and Retail segments. In addition, certain items that affect comparability (as determined by the chief operating decision maker) are not allocated to the reportable segments. (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2020 Revenues: Third party (a) $ 9,441 $ 4,778 $ 805 $ 15,024 Intersegment 1,834 1 1,169 3,004 Segment revenues $ 11,275 $ 4,779 $ 1,974 $ 18,028 Segment income (loss) from operations $ (1,619 ) $ 494 $ 869 $ (256 ) Supplemental Data Depreciation and amortization (b) $ 433 $ 132 $ 330 $ 895 Capital expenditures and investments (c) 263 74 425 762 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2019 Revenues: Third party (a) $ 23,654 $ 8,944 $ 931 $ 33,529 Intersegment 5,466 2 1,218 6,686 Segment revenues $ 29,120 $ 8,946 $ 2,149 $ 40,215 Segment income from operations $ 906 $ 493 $ 878 $ 2,277 Supplemental Data Depreciation and amortization (b) $ 411 $ 130 $ 318 $ 859 Capital expenditures and investments (c) 430 120 814 1,364 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2020 Revenues: Third party (a) $ 26,969 $ 11,547 $ 1,723 $ 40,239 Intersegment 5,451 3 2,411 7,865 Segment revenues $ 32,420 $ 11,550 $ 4,134 $ 48,104 Segment income (loss) from operations $ (2,241 ) $ 1,013 $ 1,774 $ 546 Supplemental Data Depreciation and amortization (b) $ 880 $ 257 $ 675 $ 1,812 Capital expenditures and investments (c) 722 150 899 1,771 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2019 Revenues: Third party (a) $ 43,574 $ 16,320 $ 1,888 $ 61,782 Intersegment 9,882 4 2,450 12,336 Segment revenues $ 53,456 $ 16,324 $ 4,338 $ 74,118 Segment income from operations $ 572 $ 663 $ 1,786 $ 3,021 Supplemental Data Depreciation and amortization (b) $ 838 $ 256 $ 625 $ 1,719 Capital expenditures and investments (c) 824 193 1,637 2,654 (a) Includes related party sales. See Note 6 for additional information. (b) Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other items not allocated to segments. (c) Includes changes in capital expenditure accruals and investments in affiliates. See reconciliation from segment totals to MPC consolidated total capital expenditures below. The following reconciles segment income from operations to income (loss) before income taxes as reported in the consolidated statements of income: Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Segment income (loss) from operations $ (256 ) $ 2,277 $ 546 $ 3,021 Corporate (a) (188 ) (179 ) (415 ) (370 ) Items not allocated to segments: Equity method investment restructuring gain (b) — — — 207 Transaction-related costs (c) (30 ) (34 ) (65 ) (125 ) Litigation — (22 ) — (22 ) Impairments (d) (25 ) — (9,162 ) — LCM inventory valuation adjustment (e) 1,480 — (1,740 ) — Income (loss) from operations 981 2,042 (10,836 ) 2,711 Net interest and other financial costs 345 322 683 628 Income (loss) before income taxes $ 636 $ 1,720 $ (11,519 ) $ 2,083 (a) Corporate consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. (b) Includes gain related to Capline Pipeline Company LLC (“Capline LLC”). See Note 13 . (c) 2020 includes costs incurred in connection with the Speedway separation and Midstream strategic review. 2019 includes employee severance, retention and other costs related to the acquisition of Andeavor. (d) Includes goodwill impairment, impairment of equity method investments and impairment of long lived assets. See Note 4 for additional information. (e) See Note 12 . The following reconciles segment capital expenditures and investments to total capital expenditures: Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Segment capital expenditures and investments $ 762 $ 1,364 $ 1,771 $ 2,654 Less investments in equity method investees 214 270 383 595 Plus items not allocated to segments: Corporate 18 4 45 14 Capitalized interest 27 34 56 65 Total capital expenditures (a) $ 593 $ 1,132 $ 1,489 $ 2,138 (a) Includes changes in capital expenditure accruals. See Note 19 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2020 and 2019 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, 2020
Other Income and Expenses [Abstract]
Net Interest and Other Financial Costs	NET INTEREST AND OTHER FINANCIAL COSTS Net interest and other financial costs were as follows: Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Interest income $ (2 ) $ (9 ) $ (8 ) $ (18 ) Interest expense 373 350 730 690 Interest capitalized (35 ) (35 ) (71 ) (67 ) Pension and other postretirement non-service costs (a) — 3 (3 ) — Other financial costs 9 13 35 23 Net interest and other financial costs $ 345 $ 322 $ 683 $ 628 (a) See Note 21 .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES We have historically provided for income taxes during interim reporting periods based on an estimate of the annual effective tax rate applied to the income for the year to date interim period. For 2020, we continue to utilize this approach. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was enacted in response to the COVID-19 pandemic. The CARES Act contains numerous income tax provisions, some of which materially impact MPC's calculation of income taxes including: • Revising the limitations on the deductibility of interest from 30 percent of adjusted taxable income to 50 percent. • Ability to carry back tax net operating losses ("NOL") five years for NOLs arising in taxable years 2018 through 2020. This provision allows the taxpayer to recover taxes previously paid at a 35 percent federal income tax rate during years prior to 2018. The limitation on the percentage of taxable income that may be offset by the NOL, formerly 80 percent of income, was eliminated for years beginning before 2021. We recorded an overall income tax benefit of $1.6 billion for the six months ended June 30, 2020 , of which $309 million was attributable to the tax rate differential in the carryback years resulting from the expected NOL carryback provided under the CARES Act. As of June 30, 2020 , the estimated cash tax refund resulting from the NOL carryback provided in the CARES Act is $1.1 billion and arises solely due to taxes paid in prior years. Absent the CARES Act, we would have recorded a deferred tax asset for the expected NOL carryforward under the currently effective federal income tax rate. For the three months ended June 30, 2020 , we recorded income tax expense of $360 million , which reflects a change in our estimated annual effective tax rate and CARES Act benefit. The combined federal, state and foreign income tax rate was 14 percent for the six months ended June 30, 2020 . Our effective tax benefit rate was lower than the 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 effective tax rate is generally benefited by our noncontrolling interest in MPLX, but this benefit was lower for the six months ended June 30, 2020 compared to the six months ended June 30, 2019 due to impairment charges recorded by MPLX. The combined federal, state and foreign income tax rate was 57 percent for the three months ended June 30, 2020 . The effective tax rate for the three months ended June 30, 2020 was higher than the U.S. statutory rate of 21 percent as well as higher than the effective rate for the three months ended June 30, 2019 primarily due the tax rate differential resulting from the expected NOL carryback provided under the CARES Act, permanent differences related to net income attributable to noncontrolling interests and changes in our estimated annual effective rate applied to income for the year to date interim period. Based on the estimated NOL carryback, as provided by the CARES Act, we recorded an income tax receivable of $1.1 billion in other noncurrent assets to reflect our estimate of the tax refund we expect to realize at the time of our 2020 tax return filing, which is expected during the second half of 2021. A reconciliation of the tax provision (benefit) in dollars as determined using the federal statutory income tax rate applied to income (loss) before income taxes to the (benefit) provision for income taxes is shown in the table below. Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Tax computed at statutory rate $ 133 $ 361 $ (2,419 ) $ 437 State and local income taxes, net of federal income tax effects 33 45 (167 ) 88 Goodwill impairment — — 1,156 — Noncontrolling interests 81 (68 ) 150 (83 ) CARES Act legislation 102 — (309 ) — Other 11 15 12 15 Total provision (benefit) for income tax $ 360 $ 353 $ (1,577 ) $ 457 During the first quarter of 2019, MPC’s provision for income taxes was increased $36 million for an out of period adjustment to correct the tax effects recorded in 2018 related to the Andeavor acquisition. The impact of the adjustment was not material to any previous period. We are continuously undergoing examination of our income tax returns, which have been completed through the 2005 tax year for state returns and the 2010 tax year for our U.S. federal return. As of June 30, 2020 , we had $25 million of unrecognized tax benefits. Pursuant to our tax sharing agreement with Marathon Oil, the unrecognized tax benefits related to pre-spinoff operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and we have indemnified Marathon Oil accordingly. See Note 22 for indemnification information.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2020
Inventory Disclosure [Abstract]
Inventories	INVENTORIES (In millions) June 30, December 31, Crude oil $ 3,163 $ 3,472 Refined products 5,397 5,548 Materials and supplies 1,028 996 Merchandise 238 227 Inventories before LCM inventory valuation reserve 9,826 10,243 LCM inventory valuation reserve (1,740 ) — Total $ 8,086 $ 10,243 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. At June 30, 2020, market values for these inventories were lower than their LIFO cost basis, resulting in a reserve of $1.74 billion . The reduction from the $3.22 billion LCM inventory valuation reserve at March 31, 2020 resulted in a benefit of $1.48 billion for the three months ended June 30, 2020 . The cost of inventories of crude oil and refined products and merchandise is determined primarily under the LIFO method. There were no LIFO inventory liquidations recognized for the six months ended June 30, 2020

Equity Method Investments

Equity Method Investments	6 Months Ended
	Jun. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	EQUITY METHOD INVESTMENTS During the three months ended March 31, 2019, we executed agreements with Capline Pipeline Company LLC (“Capline LLC”) to contribute our 33 percent undivided interest in the Capline pipeline system in exchange for a 33 percent ownership interest in Capline LLC. In connection with our execution of these agreements, Capline LLC initiated a binding open season for southbound service from Patoka, Illinois to St. James, Louisiana or Liberty, Mississippi with an additional origination point at Cushing, Oklahoma. Service from Cushing, Oklahoma is part of a joint tariff with Diamond pipeline. In accordance with ASC 810, we derecognized our undivided interest amounting to $143 million of net assets and recognized the Capline LLC ownership interest we received at fair value. We used an income approach to determine the fair value of our ownership interest under a Monte Carlo simulation method. We estimated the fair value of our ownership interest to be $350 million . This is a nonrecurring fair value measurement and is categorized in Level 3 of the fair value hierarchy. The Monte Carlo simulation inputs include ranges of tariff rates, operating volumes, operating cost and capital expenditure assumptions. The estimated cash flows were discounted using a Monte Carlo market participant weighted average cost of capital estimate. None of the inputs to the Monte Carlo simulation are individually significant. The excess of the estimated fair value of our ownership interest over the carrying value of the derecognized net assets resulted in a $207 million non-cash net gain recorded as a net gain on disposal of assets in the accompanying consolidated statements of income. As the Capline system is currently idled, Capline LLC is unable to fund its operations without financial support from its equity owners and is a VIE. MPC is not deemed to be the primary beneficiary, due to our inability to unilaterally control significant decision-making rights. Our maximum exposure to loss as a result of our involvement with Capline LLC includes our equity investment, any additional capital contribution commitments and any operating expenses incurred by Capline LLC in excess of compensation received for performance of the operating services.

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT (In millions) June 30, December 31, Refining & Marketing $ 29,781 $ 29,037 Retail 7,199 7,104 Midstream 27,696 27,193 Corporate 1,328 1,289 Total 66,004 64,623 Less accumulated depreciation (a) 20,979 19,008 Property, plant and equipment, net $ 45,025 $ 45,615 (a) The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during 2020. See Note 4 for additional information.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Values—Recurring The following tables present assets and liabilities accounted for at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 by fair value hierarchy level. We have elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty, including any related cash collateral as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the following tables. June 30, 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 $ 255 $ 8 $ — $ (260 ) $ 3 $ 46 Liabilities: Commodity contracts $ 350 $ 8 $ — $ (358 ) $ — $ — Embedded derivatives in commodity contracts — — 51 — 51 — December 31, 2019 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 57 $ 6 $ — $ (55 ) $ 8 $ 73 Liabilities: Commodity contracts $ 95 $ 11 $ — $ (106 ) $ — $ — Embedded derivatives in commodity contracts — — 60 — 60 — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of June 30, 2020 , cash collateral of $98 million was netted with the mark-to-market derivative liabilities. As of December 31, 2019 , cash collateral of $51 million was netted with mark-to-market derivative liabilities. (b) We have no derivative contracts that are subject to master netting arrangements reflected gross on the balance sheet. Commodity derivatives in Level 1 are exchange-traded contracts for crude oil and refined products measured at fair value with a market approach using the close-of-day settlement prices for the market. Commodity derivatives are covered under master netting agreements with an unconditional right to offset. Collateral deposits in futures commission merchant accounts covered by master netting agreements related to Level 1 commodity derivatives are classified as Level 1 in the fair value hierarchy. Level 2 instruments are valued based on quoted prices for similar assets and liabilities in active markets, and inputs other than quoted prices, such as liquidity, that are observable for the asset or liability. Commodity derivatives in Level 2 are OTC contracts, which are valued using market quotations from independent price reporting agencies, third-party brokers and commodity exchange price curves that are corroborated with market data. Level 3 instruments are OTC NGL contracts and embedded derivatives in commodity contracts. The embedded derivative liability relates to a natural gas purchase agreement embedded in a keep‑whole processing agreement. The fair value calculation for these Level 3 instruments at June 30, 2020 used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.38 to $0.92 per gallon with a weighted average of $0.53 per gallon per the current term of the embedded derivative and (2) the probability of renewal of 100 percent for the first five-year term and 100 percent for the second five-year term of the natural gas purchase agreement and the related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability. An increase in the probability of renewal would result in an increase in the fair value of the related embedded derivative liability. The following is a reconciliation of the beginning and ending balances recorded for net liabilities classified as Level 3 in the fair value hierarchy. Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Beginning balance $ 45 $ 65 $ 60 $ 61 Unrealized and realized losses included in net income 7 1 (7 ) 7 Settlements of derivative instruments (1 ) (1 ) (2 ) (3 ) Ending balance $ 51 $ 65 $ 51 $ 65 The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: $ 6 $ 2 $ (7 ) $ 5 Fair Values – Reported We believe the carrying value of our other financial instruments, including cash and cash equivalents, receivables, accounts payable and certain accrued liabilities, approximate fair value. Our fair value assessment incorporates a variety of considerations, including the short-term duration of the instruments and the expected insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. The borrowings under our revolving credit facilities and term loan facility, which include variable interest rates, approximate fair value. The fair value of our fixed and floating rate long-term debt is based on prices from recent trade activity and is categorized in level 3 of the fair value hierarchy. The carrying and fair values of our debt were approximately $31.6 billion and $33.6 billion at June 30, 2020 , respectively, and approximately $28.3 billion and $30.1 billion at December 31, 2019 , respectively. These carrying and fair values of our debt exclude the unamortized issuance costs which are netted against our total debt.

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2020
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 15 . 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 and (6) the purchase of natural gas. The following table presents the fair value of derivative instruments as of June 30, 2020 and December 31, 2019 and the line items in the balance sheets in which the fair values are reflected. The fair value amounts below are presented on a gross basis and do not reflect the netting of asset and liability positions permitted under the terms of our master netting arrangements including cash collateral on deposit with, or received from, brokers. We offset the recognized fair value amounts for multiple derivative instruments executed with the same counterparty in our financial statements when a legal right of offset exists. As a result, the asset and liability amounts below will not agree with the amounts presented in our consolidated balance sheets. (In millions) June 30, 2020 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 263 $ 358 Other current liabilities (a) — 3 Deferred credits and other liabilities (a) — 48 (In millions) December 31, 2019 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 63 $ 106 Other current liabilities (a) — 5 Deferred credits and other liabilities (a) — 55 (a) Includes embedded derivatives. The table below summarizes open commodity derivative contracts for crude oil, refined products and blending products as of June 30, 2020 . Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 94.3% 46,032 43,019 Refined products 85.3% 24,489 18,100 Blending products 86.0% 1,067 2,842 (a) Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 6,425 long and 2,875 short; Refined products - 1,525 long and 225 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 2020 2019 2020 2019 Sales and other operating revenues $ (7 ) $ 3 $ 77 $ (17 ) Cost of revenues (105 ) 15 26 (65 ) Total $ (112 ) $ 18 $ 103 $ (82 )

Debt

Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Debt	DEBT Our outstanding borrowings at June 30, 2020 and December 31, 2019 consisted of the following: (In millions) June 30, December 31, Marathon Petroleum Corporation: Senior notes $ 10,974 $ 8,474 Notes payable 10 10 Finance lease obligations 683 679 MPLX LP: Bank revolving credit facility 825 — Term loan facility 1,000 1,000 Senior notes 19,100 19,100 Finance lease obligations 13 19 Total debt $ 32,605 $ 29,282 Unamortized debt issuance costs (143 ) (134 ) Unamortized (discount) premium, net (296 ) (310 ) Amounts due within one year (1,715 ) (711 ) Total long-term debt due after one year $ 30,451 $ 28,127 Available Capacity under our Facilities as of June 30, 2020 (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Weighted Average Interest Rate Expiration MPC, excluding MPLX MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2020 MPC 364-day bank revolving credit facility 1,000 — — 1,000 — April 2021 MPC bank revolving credit facility (a) 5,000 — 1 4,999 — October 2023 MPC trade receivables securitization facility (b) 705 — — 705 — July 2021 MPLX MPLX bank revolving credit facility (c) 3,500 825 — 2,675 1.36 % July 2024 (a) Borrowed $3.5 billion and repaid $3.5 billion during the six months ended June 30, 2020. (b) Borrowed $1.175 billion and repaid $1.175 billion during the six months ended June 30, 2020 . Availability under our $750 million trade receivables facility is a function of eligible trade receivables, which will be lower in a sustained lower price environment for refined products. (c) Borrowed $2.5 billion at an average interest rate of 1.53 percent and repaid $1.675 billion during the six months ended June 30, 2020 . Additional MPC 364-Day Bank Revolving Credit Facility On April 27, 2020, MPC entered into a credit agreement with a syndicate of lenders providing for an additional $1 billion 364-day revolving credit facility. The credit agreement for the additional 364-day revolving credit facility contains representations and warranties, affirmative and negative covenants and events of default that we consider customary for agreements of their nature and type and substantially similar to those contained in our existing $5 billion five-year revolving credit facility and $1 billion 364-day revolving credit facility. MPC Senior Notes Issuance On April 27, 2020, we closed on the issuance of $2.5 billion in aggregate principal amount of senior notes in a public offering, consisting of $1.25 billion aggregate principal amount of 4.500 percent unsecured senior notes due May 2023 and $1.25 billion aggregate principal amount of 4.700 percent unsecured senior notes due May 2025. Interest is payable semi-annually in arrears. MPC used the net proceeds from this offering to repay certain amounts outstanding under its five-year revolving credit facility.

Revenue

Revenue	6 Months Ended
	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE The following table presents our revenues disaggregated by segment and product line. (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2020 Refined products $ 8,341 $ 3,160 $ 120 $ 11,621 Merchandise — 1,599 — 1,599 Crude oil 1,003 — — 1,003 Midstream services and other 97 19 685 801 Sales and other operating revenues $ 9,441 $ 4,778 $ 805 $ 15,024 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2019 Refined products $ 22,221 $ 7,303 $ 190 $ 29,714 Merchandise 1 1,613 — 1,614 Crude oil 1,310 — — 1,310 Midstream services and other 122 28 741 891 Sales and other operating revenues $ 23,654 $ 8,944 $ 931 $ 33,529 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2020 Refined products $ 24,880 $ 8,449 $ 289 $ 33,618 Merchandise 1 3,055 — 3,056 Crude oil 1,878 — — 1,878 Midstream services and other 210 43 1,434 1,687 Sales and other operating revenues $ 26,969 $ 11,547 $ 1,723 $ 40,239 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2019 Refined products $ 40,971 $ 13,250 $ 406 $ 54,627 Merchandise 2 3,022 — 3,024 Crude oil 2,381 — — 2,381 Midstream services and other 220 48 1,482 1,750 Sales and other operating revenues $ 43,574 $ 16,320 $ 1,888 $ 61,782 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, 2020 , 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, 2020 include matching buy/sell receivables of $1.01 billion

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION Six Months Ended (In millions) 2020 2019 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 601 $ 579 Net income taxes paid to taxing authorities 6 362 Non-cash investing and financing activities: Contribution of assets (a) — 143 Fair value of assets acquired (b) — 350 (a) 2019 includes the contribution of net assets to Capline LLC. See Note 13 . (b) 2019 includes the recognition of the Capline LLC equity method investment. See Note 13 . (In millions) June 30, December 31, Cash and cash equivalents $ 1,091 $ 1,527 Restricted cash (a) 2 2 Cash, cash equivalents and restricted cash $ 1,093 $ 1,529 (a) 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) 2020 2019 Additions to property, plant and equipment per the consolidated statements of cash flows $ 1,910 $ 2,419 Decrease in capital accruals (421 ) (281 ) Total capital expenditures $ 1,489 $ 2,138

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2018 $ (132 ) $ (23 ) $ 2 $ 9 $ (144 ) Other comprehensive income (loss) before reclassifications, net of tax of ($3) (7 ) 1 — — (6 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (23 ) — — — (23 ) – actuarial loss (a) 11 (1 ) — — 10 – settlement loss (a) 2 — — — 2 Other — — — (3 ) (3 ) Tax effect 2 — — 1 3 Other comprehensive loss (15 ) — — (2 ) (17 ) Balance as of June 30, 2019 $ (147 ) $ (23 ) $ 2 $ 7 $ (161 ) (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 ) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 21 .

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	6 Months Ended
	Jun. 30, 2020
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 June 30, Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Components of net periodic benefit cost: Service cost 83 60 9 8 Interest cost 24 27 9 10 Expected return on plan assets (32 ) (31 ) — — Amortization – prior service credit (12 ) (12 ) — — – actuarial loss 10 7 — (1 ) – settlement loss 1 2 — — Net periodic benefit cost 74 53 18 17 Six Months Ended June 30, Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Components of net periodic benefit cost: Service cost $ 152 $ 118 $ 18 $ 16 Interest cost 49 55 17 19 Expected return on plan assets (66 ) (63 ) — — Amortization – prior service credit (23 ) (23 ) — — – actuarial loss 18 11 1 (1 ) – settlement loss 1 2 — — Net periodic benefit cost $ 131 $ 100 $ 36 $ 34 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, 2020 , we made contributions of $3 million to our funded pension plans. Benefit payments related to unfunded pension and other postretirement benefit plans were $40 million and $20 million , respectively, during the six months ended June 30, 2020 .

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which we have not recorded a liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material. Environmental Matters We are subject to federal, state, local and foreign laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites and certain other locations including presently or formerly owned or operated retail marketing sites. Penalties may be imposed for noncompliance. At June 30, 2020 and December 31, 2019 , accrued liabilities for remediation totaled $412 million and $433 million , respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, that may be imposed. Receivables for recoverable costs from certain states, under programs to assist companies in clean-up efforts related to underground storage tanks at presently or formerly owned or operated retail marketing sites, were $28 million and $29 million at June 30, 2020 and December 31, 2019 , respectively. Governmental and other entities in California, Hawaii, Maryland, New York and Rhode Island have filed lawsuits against coal, gas, oil and petroleum companies, including the Company. The lawsuits allege damages as a result of climate change and the plaintiffs are seeking unspecified damages and abatement under various tort theories. Similar lawsuits may be filed in other jurisdictions. At this early stage, the ultimate outcome of these matters remains 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 May 2015, the Kentucky attorney general filed a lawsuit against our wholly owned subsidiary, Marathon Petroleum Company LP (“MPC LP”), in the United States District Court for the Western District of Kentucky asserting claims under federal and state antitrust statutes, the Kentucky Consumer Protection Act, and state common law. The complaint, as amended in July 2015, alleges that MPC LP used deed restrictions, supply agreements with customers and exchange agreements with competitors to unreasonably restrain trade in areas within Kentucky and seeks declaratory relief, unspecified damages, civil penalties, restitution and disgorgement of profits. On June 1, 2020, the trial court granted our motion for summary judgment and dismissed all federal law claims with prejudice. State-based claims were dismissed without prejudice. In early July 2020, MPLX received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification covers the rights of way for 23 tracts of land and demands the immediate cessation of pipeline operations. The notification also assesses trespass damages of approximately $187 million . MPLX expects to receive a notification for an additional 11 tracts in the near future. MPLX appealed this determination, which triggered an automatic stay of the requested pipeline shutdown and payment. We believe the trespass damage calculation is dependent on a novel interpretation of the applicable law, and MPLX continues to actively negotiate 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, 2020 . Gray Oak Pipeline, LLC In connection with our 25 percent interest in Gray Oak Pipeline, LLC (“Gray Oak Pipeline”), we have entered into an Equity Contribution Agreement obligating us to make certain equity contributions to Gray Oak Pipeline to support its obligations under a construction loan facility. Gray Oak oil pipeline is a crude oil transportation system from West Texas and the Eagle Ford formation to destinations in the Ingleside, Corpus Christi and Sweeney, Texas markets. Gray Oak Pipeline entered into the construction loan facility with a syndicate of banks to finance a portion of the construction costs of the pipeline project. The Equity Contribution Agreement requires us to contribute our pro rata share of any amounts necessary to allow Gray Oak Pipeline to cure any payment defaults under the construction loan facility or to repay all amounts outstanding under the facility, including principal, accrued interest, fees and expenses, in certain circumstances, including the failure of Gray Oak Pipeline to repay or refinance the construction loan facility prior to its scheduled maturity date of June 3, 2022. Gray Oak Pipeline may borrow up to $1.43 billion under the construction loan facility (after giving effect to the exercise of all options to increase its borrowing capacity). As of June 30, 2020 , our maximum potential undiscounted payments under the Equity Contribution Agreement for the debt principal totaled $345 million . 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 has entered into a Contingent Equity Contribution Agreement. MPLX, along with the other joint venture owners in the Bakken Pipeline system, have 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 for the Bakken Pipeline system, to conduct a full environmental impact statement (“EIS”), and further requested briefing on whether an easement permit 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 permit 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 are appealing the D.D.C.’s orders to the U.S. Court of Appeals for the District of Columbia Circuit. On July 14, 2020, the Circuit Court issued an administrative stay while the court considers Dakota Access and the Army Corps’ emergency motion for stay pending appeal. 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, 2020 , our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement was 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, 2020 , our maximum potential undiscounted payments under this agreement for debt principal totaled $125 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, 2020 , our maximum potential undiscounted payments under this arrangement was $118 million . Marathon Oil indemnifications — The separation and distribution agreement and other agreements with Marathon Oil to effect our spinoff provide for cross-indemnities between Marathon Oil and us. In general, Marathon Oil is required to indemnify us for any liabilities relating to Marathon Oil’s historical oil and gas exploration and production operations, oil sands mining operations and integrated gas operations, and we are required to indemnify Marathon Oil for any liabilities relating to Marathon Oil’s historical refining, marketing and transportation operations. The terms of these indemnifications are indefinite and the amounts are not capped. Other guarantees —We have entered into other guarantees with maximum potential undiscounted payments totaling $104 million as of June 30, 2020 , which primarily consist of a commitment to contribute cash to an equity method investee for certain catastrophic events, in lieu of procuring insurance coverage, a commitment to fund a share of the bonds issued by a government entity for construction of public utilities in the event that other industrial users of the facility default on their utility payments and leases of assets containing general lease indemnities and guaranteed residual values. General guarantees associated with dispositions —Over the years, we have sold various assets in the normal course of our business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based. Contractual Commitments and Contingencies At June 30, 2020 , our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $678 million .

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Agreement to sell our Speedway business On August 2, 2020, we entered into a definitive agreement to sell Speedway, our company-owned and operated retail transportation fuel and convenience store business, to 7-Eleven, Inc. for $21 billion in cash. The taxable transaction is expected to close in the first quarter of 2021, subject to customary closing conditions and regulatory approvals. The Speedway business is currently a reporting unit within our Retail segment. Our Retail segment also includes the results of our direct dealer business, which we will retain after the closing of this transaction. In connection with the signing of this agreement, we expect to account for the Speedway business as Assets Held for Sale starting in the third quarter of 2020. As a result, the prospective and historical results of the Speedway business will be presented as discontinued operations in our consolidated financial statements. Redemption of business from MPLX On July 31, 2020, Western Refining Southwest, Inc. (“WRSW”), a wholly owned subsidiary of MPC, entered into a Redemption Agreement (the “Redemption Agreement”) with MPLX, pursuant to which MPLX agreed to transfer to WRSW, all of the outstanding membership interests in Western Refining Wholesale, LLC, (“WRW”) in exchange for the redemption of MPLX common units held by WRSW. The transactions effects the transfer to MPC of the Western wholesale distribution business that MPLX acquired as a result of its acquisition of ANDX. The results of these operations will be presented in MPC’s Refining & Marketing segment prospectively. At the Closing, per the terms of Redemption Agreement, MPLX redeemed 18,582,088 Common Units (the “Redeemed Units”) held by WRSW The number of Redeemed Units was calculated by dividing WRW’s aggregate valuation of $340 million by the simple average of the volume weighted average New York Stock Exchange prices of an MPLX Common Unit for the ten trading days ending at market close on July 27, 2020. The transaction will result in a minor decrease in MPC’s beneficial ownership interest in MPLX.

Description of the Business a_2

Description of the Business and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2020
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.
Credit Loss	We are exposed to credit losses primarily through our sales of refined petroleum products, crude oil and midstream services. We assess each customer’s ability to pay through our credit review process. The credit review process considers various factors such as external credit ratings, a review of financial statements to determine liquidity, leverage, trends and business specific risks, market information, pay history and our business strategy. Customers that do not qualify for payment terms are required to prepay or provide a letter of credit. We monitor our ongoing credit exposure through timely review of customer payment activity.
Inventories	The cost of inventories of crude oil and refined products and merchandise is determined primarily under the LIFO method.
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 and (6) the purchase of natural gas.

Master Limited Partnership (Tab

Master Limited Partnership (Tables)	6 Months Ended
	Jun. 30, 2020
Noncontrolling Interest [Abstract]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net	As a result of equity transactions of MPLX and ANDX, we are required to adjust non-controlling interest and additional paid-in capital. Changes in MPC’s additional paid-in capital resulting from changes in its ownership interests in MPLX and ANDX were as follows: Six Months Ended (In millions) 2020 2019 Increase due to the issuance of MPLX & ANDX common units $ 4 $ 7 Tax impact (1 ) (2 ) Increase in MPC's additional paid-in capital, net of tax $ 3 $ 5

Impairments (Tables)

Impairments (Tables)	6 Months Ended
	Jun. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Details of Impairments	The table below provides information related to the impairments recognized during the three and six months ended June 30, 2020 and the location of these impairments within the consolidated statements of income. Three Months Ended Six Months Ended (In millions) Income Statement Line 2020 2020 Goodwill Impairment expense $ — $ 7,330 Equity method investments Income (loss) from equity method investments — 1,315 Long-lived assets Impairment expense (a) 25 517 Total impairments $ 25 $ 9,162
Schedule of Goodwill	The changes in carrying amount of goodwill were as follows: (In millions) Refining & Marketing Retail Midstream Total Balance at January 1, 2020 $ 5,572 $ 4,951 $ 9,517 $ 20,040 Impairments (5,516 ) — (1,814 ) (7,330 ) Transfers (56 ) — 56 — Balance at June 30, 2020 $ — $ 4,951 $ 7,759 $ 12,710

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities [Table Text Block]	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 $ 67 $ 15 Receivables, less allowance for doubtful accounts 567 615 Inventories 115 110 Other current assets 49 110 Equity method investments 4,065 5,275 Property, plant and equipment, net 21,958 22,174 Goodwill 7,722 9,536 Right of use assets 341 365 Other noncurrent assets 1,074 1,323 Liabilities Accounts payable $ 471 $ 744 Payroll and benefits payable 2 5 Accrued taxes 83 80 Debt due within one year 3 9 Operating lease liabilities 69 66 Other current liabilities 265 259 Long-term debt 20,556 19,704 Deferred income taxes 11 12 Long-term operating lease liabilities 274 302 Deferred credits and other liabilities 442 409

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2020
Related Party Transactions [Abstract]
Sales to Related Parties	Transactions with related parties were as follows: Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Sales to related parties $ 106 $ 186 $ 271 $ 372 Purchases from related parties 158 183 353 387 Sales to related parties, which are included in sales and other operating revenues, consist primarily of sales of refined products to PFJ Southeast, an equity affiliate which owns and operates travel plazas primarily in the Southeast region of the United States.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2020
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) 2020 2019 2020 2019 Basic Allocation of earnings: Net income (loss) attributable to MPC $ 9 $ 1,106 $ (9,225 ) $ 1,099 Income allocated to participating securities — — — 1 Income (loss) available to common stockholders – basic $ 9 $ 1,106 $ (9,225 ) $ 1,098 Weighted average common shares outstanding 650 662 649 667 Basic earnings (loss) per share $ 0.01 $ 1.67 $ (14.21 ) $ 1.65 Diluted Allocation of earnings: Net income (loss) attributable to MPC $ 9 $ 1,106 $ (9,225 ) $ 1,099 Income allocated to participating securities — — — 1 Income (loss) available to common stockholders – diluted $ 9 $ 1,106 $ (9,225 ) $ 1,098 Weighted average common shares outstanding 650 662 649 667 Effect of dilutive securities 3 4 — 5 Weighted average common shares, including dilutive effect 653 666 649 672 Diluted earnings (loss) per share $ 0.01 $ 1.66 $ (14.21 ) $ 1.63
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) 2020 2019 2020 2019 Shares issuable under stock-based compensation plans 9 4 11 3

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Share Repurchases	Total share repurchases were as follows for the respective periods: Three Months Ended Six Months Ended (In millions, except per share data) 2020 2019 2020 2019 Number of shares repurchased — 9 — 23 Cash paid for shares repurchased $ — $ 500 $ — $ 1,385 Average cost per share $ — $ 57.18 $ — $ 60.75

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Income From Operations Attributable To Operating Segments	Segment income represents income (loss) from operations attributable to the reportable segments. Corporate administrative expenses, except for those attributable to MPLX, and costs related to certain non-operating assets are not allocated to the Refining & Marketing and Retail segments. In addition, certain items that affect comparability (as determined by the chief operating decision maker) are not allocated to the reportable segments. (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2020 Revenues: Third party (a) $ 9,441 $ 4,778 $ 805 $ 15,024 Intersegment 1,834 1 1,169 3,004 Segment revenues $ 11,275 $ 4,779 $ 1,974 $ 18,028 Segment income (loss) from operations $ (1,619 ) $ 494 $ 869 $ (256 ) Supplemental Data Depreciation and amortization (b) $ 433 $ 132 $ 330 $ 895 Capital expenditures and investments (c) 263 74 425 762 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2019 Revenues: Third party (a) $ 23,654 $ 8,944 $ 931 $ 33,529 Intersegment 5,466 2 1,218 6,686 Segment revenues $ 29,120 $ 8,946 $ 2,149 $ 40,215 Segment income from operations $ 906 $ 493 $ 878 $ 2,277 Supplemental Data Depreciation and amortization (b) $ 411 $ 130 $ 318 $ 859 Capital expenditures and investments (c) 430 120 814 1,364 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2020 Revenues: Third party (a) $ 26,969 $ 11,547 $ 1,723 $ 40,239 Intersegment 5,451 3 2,411 7,865 Segment revenues $ 32,420 $ 11,550 $ 4,134 $ 48,104 Segment income (loss) from operations $ (2,241 ) $ 1,013 $ 1,774 $ 546 Supplemental Data Depreciation and amortization (b) $ 880 $ 257 $ 675 $ 1,812 Capital expenditures and investments (c) 722 150 899 1,771 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2019 Revenues: Third party (a) $ 43,574 $ 16,320 $ 1,888 $ 61,782 Intersegment 9,882 4 2,450 12,336 Segment revenues $ 53,456 $ 16,324 $ 4,338 $ 74,118 Segment income from operations $ 572 $ 663 $ 1,786 $ 3,021 Supplemental Data Depreciation and amortization (b) $ 838 $ 256 $ 625 $ 1,719 Capital expenditures and investments (c) 824 193 1,637 2,654 (a) Includes related party sales. See Note 6 for additional information. (b) Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other items not allocated to segments. (c) Includes changes in capital expenditure accruals and investments in affiliates. See reconciliation from segment totals to MPC consolidated total capital expenditures below.
Reconciliation Of Segment Income From Operations To Income Before Income Taxes	The following reconciles segment income from operations to income (loss) before income taxes as reported in the consolidated statements of income: Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Segment income (loss) from operations $ (256 ) $ 2,277 $ 546 $ 3,021 Corporate (a) (188 ) (179 ) (415 ) (370 ) Items not allocated to segments: Equity method investment restructuring gain (b) — — — 207 Transaction-related costs (c) (30 ) (34 ) (65 ) (125 ) Litigation — (22 ) — (22 ) Impairments (d) (25 ) — (9,162 ) — LCM inventory valuation adjustment (e) 1,480 — (1,740 ) — Income (loss) from operations 981 2,042 (10,836 ) 2,711 Net interest and other financial costs 345 322 683 628 Income (loss) before income taxes $ 636 $ 1,720 $ (11,519 ) $ 2,083 (a) Corporate consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. (b) Includes gain related to Capline Pipeline Company LLC (“Capline LLC”). See Note 13 . (c) 2020 includes costs incurred in connection with the Speedway separation and Midstream strategic review. 2019 includes employee severance, retention and other costs related to the acquisition of Andeavor. (d) Includes goodwill impairment, impairment of equity method investments and impairment of long lived assets. See Note 4 for additional information. (e) See Note 12 .
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) 2020 2019 2020 2019 Segment capital expenditures and investments $ 762 $ 1,364 $ 1,771 $ 2,654 Less investments in equity method investees 214 270 383 595 Plus items not allocated to segments: Corporate 18 4 45 14 Capitalized interest 27 34 56 65 Total capital expenditures (a) $ 593 $ 1,132 $ 1,489 $ 2,138 (a) Includes changes in capital expenditure accruals. See Note 19 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2020 and 2019 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, 2020
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) 2020 2019 2020 2019 Interest income $ (2 ) $ (9 ) $ (8 ) $ (18 ) Interest expense 373 350 730 690 Interest capitalized (35 ) (35 ) (71 ) (67 ) Pension and other postretirement non-service costs (a) — 3 (3 ) — Other financial costs 9 13 35 23 Net interest and other financial costs $ 345 $ 322 $ 683 $ 628 (a) See Note 21 .

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the tax provision (benefit) in dollars as determined using the federal statutory income tax rate applied to income (loss) before income taxes to the (benefit) provision for income taxes is shown in the table below. Three Months Ended Six Months Ended (In millions) 2020 2019 2020 2019 Tax computed at statutory rate $ 133 $ 361 $ (2,419 ) $ 437 State and local income taxes, net of federal income tax effects 33 45 (167 ) 88 Goodwill impairment — — 1,156 — Noncontrolling interests 81 (68 ) 150 (83 ) CARES Act legislation 102 — (309 ) — Other 11 15 12 15 Total provision (benefit) for income tax $ 360 $ 353 $ (1,577 ) $ 457

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2020
Inventory Disclosure [Abstract]
Summary Of Inventories	(In millions) June 30, December 31, Crude oil $ 3,163 $ 3,472 Refined products 5,397 5,548 Materials and supplies 1,028 996 Merchandise 238 227 Inventories before LCM inventory valuation reserve 9,826 10,243 LCM inventory valuation reserve (1,740 ) — Total $ 8,086 $ 10,243

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2020
Property, Plant and Equipment [Abstract]
Summary Of Property, Plant And Equipment	(In millions) June 30, December 31, Refining & Marketing $ 29,781 $ 29,037 Retail 7,199 7,104 Midstream 27,696 27,193 Corporate 1,328 1,289 Total 66,004 64,623 Less accumulated depreciation (a) 20,979 19,008 Property, plant and equipment, net $ 45,025 $ 45,615 (a) The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during 2020. See Note 4 for additional information.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Assets and Liabilities Accounted for at Fair Value on Recurring Basis	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of June 30, 2020 and December 31, 2019 by fair value hierarchy level. We have elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty, including any related cash collateral as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the following tables. June 30, 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 $ 255 $ 8 $ — $ (260 ) $ 3 $ 46 Liabilities: Commodity contracts $ 350 $ 8 $ — $ (358 ) $ — $ — Embedded derivatives in commodity contracts — — 51 — 51 — December 31, 2019 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 57 $ 6 $ — $ (55 ) $ 8 $ 73 Liabilities: Commodity contracts $ 95 $ 11 $ — $ (106 ) $ — $ — Embedded derivatives in commodity contracts — — 60 — 60 — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of June 30, 2020 , cash collateral of $98 million was netted with the mark-to-market derivative liabilities. As of December 31, 2019 , cash collateral of $51 million was netted with mark-to-market derivative liabilities. (b) We have no derivative contracts 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) 2020 2019 2020 2019 Beginning balance $ 45 $ 65 $ 60 $ 61 Unrealized and realized losses included in net income 7 1 (7 ) 7 Settlements of derivative instruments (1 ) (1 ) (2 ) (3 ) Ending balance $ 51 $ 65 $ 51 $ 65 The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: $ 6 $ 2 $ (7 ) $ 5

Derivatives (Tables)

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2020
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, 2020 and December 31, 2019 and the line items in the balance sheets in which the fair values are reflected. The fair value amounts below are presented on a gross basis and do not reflect the netting of asset and liability positions permitted under the terms of our master netting arrangements including cash collateral on deposit with, or received from, brokers. We offset the recognized fair value amounts for multiple derivative instruments executed with the same counterparty in our financial statements when a legal right of offset exists. As a result, the asset and liability amounts below will not agree with the amounts presented in our consolidated balance sheets. (In millions) June 30, 2020 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 263 $ 358 Other current liabilities (a) — 3 Deferred credits and other liabilities (a) — 48 (In millions) December 31, 2019 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 63 $ 106 Other current liabilities (a) — 5 Deferred credits and other liabilities (a) — 55 (a) Includes embedded derivatives.
Open Commodity Derivative Contracts	The table below summarizes open commodity derivative contracts for crude oil, refined products and blending products as of June 30, 2020 . Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 94.3% 46,032 43,019 Refined products 85.3% 24,489 18,100 Blending products 86.0% 1,067 2,842 (a) Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 6,425 long and 2,875 short; Refined products - 1,525 long and 225 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 2020 2019 2020 2019 Sales and other operating revenues $ (7 ) $ 3 $ 77 $ (17 ) Cost of revenues (105 ) 15 26 (65 ) Total $ (112 ) $ 18 $ 103 $ (82 )

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Outstanding Borrowings	Our outstanding borrowings at June 30, 2020 and December 31, 2019 consisted of the following: (In millions) June 30, December 31, Marathon Petroleum Corporation: Senior notes $ 10,974 $ 8,474 Notes payable 10 10 Finance lease obligations 683 679 MPLX LP: Bank revolving credit facility 825 — Term loan facility 1,000 1,000 Senior notes 19,100 19,100 Finance lease obligations 13 19 Total debt $ 32,605 $ 29,282 Unamortized debt issuance costs (143 ) (134 ) Unamortized (discount) premium, net (296 ) (310 ) Amounts due within one year (1,715 ) (711 ) Total long-term debt due after one year $ 30,451 $ 28,127
Schedule of Line of Credit Facilities [Table Text Block]	Available Capacity under our Facilities as of June 30, 2020 (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Weighted Average Interest Rate Expiration MPC, excluding MPLX MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2020 MPC 364-day bank revolving credit facility 1,000 — — 1,000 — April 2021 MPC bank revolving credit facility (a) 5,000 — 1 4,999 — October 2023 MPC trade receivables securitization facility (b) 705 — — 705 — July 2021 MPLX MPLX bank revolving credit facility (c) 3,500 825 — 2,675 1.36 % July 2024 (a) Borrowed $3.5 billion and repaid $3.5 billion during the six months ended June 30, 2020. (b) Borrowed $1.175 billion and repaid $1.175 billion during the six months ended June 30, 2020 . Availability under our $750 million trade receivables facility is a function of eligible trade receivables, which will be lower in a sustained lower price environment for refined products. (c) Borrowed $2.5 billion at an average interest rate of 1.53 percent and repaid $1.675 billion during the six months ended June 30, 2020 .

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue from External Customers by Products and Services [Table Text Block]	The following table presents our revenues disaggregated by segment and product line. (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2020 Refined products $ 8,341 $ 3,160 $ 120 $ 11,621 Merchandise — 1,599 — 1,599 Crude oil 1,003 — — 1,003 Midstream services and other 97 19 685 801 Sales and other operating revenues $ 9,441 $ 4,778 $ 805 $ 15,024 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended June 30, 2019 Refined products $ 22,221 $ 7,303 $ 190 $ 29,714 Merchandise 1 1,613 — 1,614 Crude oil 1,310 — — 1,310 Midstream services and other 122 28 741 891 Sales and other operating revenues $ 23,654 $ 8,944 $ 931 $ 33,529 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2020 Refined products $ 24,880 $ 8,449 $ 289 $ 33,618 Merchandise 1 3,055 — 3,056 Crude oil 1,878 — — 1,878 Midstream services and other 210 43 1,434 1,687 Sales and other operating revenues $ 26,969 $ 11,547 $ 1,723 $ 40,239 (In millions) Refining & Marketing Retail Midstream Total Six Months Ended June 30, 2019 Refined products $ 40,971 $ 13,250 $ 406 $ 54,627 Merchandise 2 3,022 — 3,024 Crude oil 2,381 — — 2,381 Midstream services and other 220 48 1,482 1,750 Sales and other operating revenues $ 43,574 $ 16,320 $ 1,888 $ 61,782

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information	Six Months Ended (In millions) 2020 2019 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 601 $ 579 Net income taxes paid to taxing authorities 6 362 Non-cash investing and financing activities: Contribution of assets (a) — 143 Fair value of assets acquired (b) — 350 (a) 2019 includes the contribution of net assets to Capline LLC. See Note 13 . (b) 2019 includes the recognition of the Capline LLC equity method investment. See Note 13 .
Schedule of Cash and Cash Equivalents	(In millions) June 30, December 31, Cash and cash equivalents $ 1,091 $ 1,527 Restricted cash (a) 2 2 Cash, cash equivalents and restricted cash $ 1,093 $ 1,529 (a) 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) 2020 2019 Additions to property, plant and equipment per the consolidated statements of cash flows $ 1,910 $ 2,419 Decrease in capital accruals (421 ) (281 ) Total capital expenditures $ 1,489 $ 2,138

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Changes in Accumulated Other Comprehensive Loss by Component	The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2018 $ (132 ) $ (23 ) $ 2 $ 9 $ (144 ) Other comprehensive income (loss) before reclassifications, net of tax of ($3) (7 ) 1 — — (6 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (23 ) — — — (23 ) – actuarial loss (a) 11 (1 ) — — 10 – settlement loss (a) 2 — — — 2 Other — — — (3 ) (3 ) Tax effect 2 — — 1 3 Other comprehensive loss (15 ) — — (2 ) (17 ) Balance as of June 30, 2019 $ (147 ) $ (23 ) $ 2 $ 7 $ (161 ) (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 ) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 21 .

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	6 Months Ended
	Jun. 30, 2020
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Costs	The following summarizes the components of net periodic benefit costs: Three Months Ended June 30, Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Components of net periodic benefit cost: Service cost 83 60 9 8 Interest cost 24 27 9 10 Expected return on plan assets (32 ) (31 ) — — Amortization – prior service credit (12 ) (12 ) — — – actuarial loss 10 7 — (1 ) – settlement loss 1 2 — — Net periodic benefit cost 74 53 18 17 Six Months Ended June 30, Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Components of net periodic benefit cost: Service cost $ 152 $ 118 $ 18 $ 16 Interest cost 49 55 17 19 Expected return on plan assets (66 ) (63 ) — — Amortization – prior service credit (23 ) (23 ) — — – actuarial loss 18 11 1 (1 ) – settlement loss 1 2 — — Net periodic benefit cost $ 131 $ 100 $ 36 $ 34

Description of the Business a_3

Description of the Business and Basis of Presentation (Details)	Jun. 30, 2020Store
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of branded outlets	7,000
Number of retail transportation fuel and convenience stores	3,870
Number of direct dealer locations	1,070

Accounting Standards (Details)

Accounting Standards (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounting Standards Update and Change in Accounting Principle [Abstract]
Receivables, less allowance for doubtful accounts	$ 4,361	$ 7,479
Allowance for doubtful accounts	$ 18	$ 17

Master Limited Partnership (Det

Master Limited Partnership (Details)	Jun. 30, 2020
MPLX | Marathon Petroleum Corporation
MPC's partnership interest in MLP (in percentage)	63.00%

Master Limited Partnership (MPL

Master Limited Partnership (MPLX's Acquisition of ANDX) (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity transactions of MPLX & ANDX		$ 6	$ (7)	$ 1	$ 2
ANDX
Preferred units, outstanding	600,000
MPLX | Series B Preferred Stock
Preferred units, outstanding	600,000
Preferred Partner | Preferred Class B
Distribution declared, per unit	$ 68.75
Additional Paid-in Capital
Equity transactions of MPLX & ANDX	$ (55)	$ 8	$ (5)	$ 2	$ 3	$ 3	$ 5
Deferred income tax impact from changes in equity	$ (642)					$ (1)	$ (2)
Public
Common units conversion ratio	1.135
Marathon Petroleum Corporation
Common units conversion ratio	1.0328

Master Limited Partnership (Non

Master Limited Partnership (Noncontrolling Interest) (Details) - USD ($) $ in Millions	Jul. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Increase in MPC's additional paid-in capital, net of tax		$ 6	$ (7)	$ 1	$ 2
Additional Paid-in Capital
Increase due to the issuance of MPLX & ANDX common units						$ 4	$ 7
Tax impact	$ (642)					(1)	(2)
Increase in MPC's additional paid-in capital, net of tax	$ (55)	$ 8	$ (5)	$ 2	$ 3	$ 3	$ 5

Impairments (Income Statement L

Impairments (Income Statement Location of Impairments) (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment			$ 7,330	$ 7,330
Equity method investment impairment			$ 1,315
Total impairments	$ 25			9,162
Property, plant and equipment, net	45,025			45,025	$ 45,615
Midstream
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment				1,814
Midstream | Terminal
Finite-Lived Intangible Assets [Line Items]
Property, plant and equipment, net	10			10
Impairment expense
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	0			7,330
Long-lived assets impairment	25	[1]		517
Income (loss) from equity method investments
Finite-Lived Intangible Assets [Line Items]
Equity method investment impairment	$ 0			$ 1,315
[1]	Impairment expense in the three months ended June 30, 2020 is related to a Midstream terminal asset with remaining net book value of $10 million .

Impairments (Goodwill) (Details

Impairments (Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 7,330	$ 7,330
Discounted Cash Flow | Discount Rate | Minimum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs	9.00%
Discounted Cash Flow | Discount Rate | Maximum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs	13.50%

Impairments (Schedule of Goodwi

Impairments (Schedule of Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020
Goodwill [Line Items]
Goodwill, beginning balance	$ 20,040	$ 20,040
Impairments	(7,330)	(7,330)
Transfers		0
Goodwill, ending balance		12,710
Refining & Marketing
Goodwill [Line Items]
Goodwill, beginning balance	5,572	5,572
Impairments		(5,516)
Transfers		(56)
Goodwill, ending balance		0
Retail
Goodwill [Line Items]
Goodwill, beginning balance	4,951	4,951
Impairments		0
Transfers		0
Goodwill, ending balance		4,951
Midstream
Goodwill [Line Items]
Goodwill, beginning balance	$ 9,517	9,517
Impairments		(1,814)
Transfers		56
Goodwill, ending balance		$ 7,759

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) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Jun. 30, 2020
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
Minimum
Finite-Lived Intangible Assets [Line Items]
Reporting unit, percentage of fair value in excess of carrying amount		17.00%

Variable Interest Entities (Con

Variable Interest Entities (Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets
Cash and cash equivalents	$ 1,091	$ 1,527
Receivables, less allowance for doubtful accounts	4,361	7,479
Inventories	8,086	10,243
Other current assets	1,105	921
Equity method investments	5,740	6,898
Property, plant and equipment, net	45,025	45,615
Goodwill	12,710	20,040
Right of use assets	2,454	2,459
Other noncurrent assets	4,021	3,374
Liabilities
Accounts payable	6,110	11,623
Payroll and benefits payable	815	1,126
Accrued taxes	1,272	1,186
Debt due within one year	1,715	711
Operating lease liabilities	625	604
Other current liabilities	967	897
Long-term debt	30,451	28,127
Deferred income taxes	5,914	6,392
Long-term operating lease liabilities	1,850	1,875
Deferred credits and other liabilities	1,285	1,265
Variable Interest Entity, Primary Beneficiary [Member] | MPLX
Assets
Cash and cash equivalents	67	15
Receivables, less allowance for doubtful accounts	567	615
Inventories	115	110
Other current assets	49	110
Equity method investments	4,065	5,275
Property, plant and equipment, net	21,958	22,174
Goodwill	7,722	9,536
Right of use assets	341	365
Other noncurrent assets	1,074	1,323
Liabilities
Accounts payable	471	744
Payroll and benefits payable	2	5
Accrued taxes	83	80
Debt due within one year	3	9
Operating lease liabilities	69	66
Other current liabilities	265	259
Long-term debt	20,556	19,704
Deferred income taxes	11	12
Long-term operating lease liabilities	274	302
Deferred credits and other liabilities	$ 442	$ 409

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Related Party Transactions [Abstract]
Sales to related parties	$ 106	$ 186	$ 271	$ 372
Purchases from related parties	$ 158	$ 183	$ 353	$ 387

Earnings Per Share (Summary of

Earnings Per Share (Summary of Earnings Per Share) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Basic
Net income (loss) attributable to MPC	$ 9	$ 1,106	$ (9,225)	$ 1,099
Income allocated to participating securities	0	0	0	1
Income (loss) available to common stockholders – basic	$ 9	$ 1,106	$ (9,225)	$ 1,098
Weighted average common shares outstanding (in shares)	650	662	649	667
Basic earnings (loss) per share	$ 0.01	$ 1.67	$ (14.21)	$ 1.65
Diluted
Net income (loss) attributable to MPC	$ 9	$ 1,106	$ (9,225)	$ 1,099
Income allocated to participating securities	0	0	0	1
Income (loss) available to common stockholders – diluted	$ 9	$ 1,106	$ (9,225)	$ 1,098
Weighted average common shares outstanding (in shares)	650	662	649	667
Effect of dilutive securities (in shares)	3	4	0	5
Weighted average common shares, including dilutive effect (in shares)	653	666	649	672
Diluted earnings (loss) per share	$ 0.01	$ 1.66	$ (14.21)	$ 1.63

Earnings Per Share (Anti-diluti

Earnings Per Share (Anti-dilutive Shares) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock Based Compensation Expense [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable under stock-based compensation plans	9	4	11	3

Equity (Additional Information)

Equity (Additional Information) (Detail) $ in Millions	Jun. 30, 2020USD ($)
Equity [Abstract]
Stock repurchase program, remaining authorized repurchase amount	$ 2,960

Equity (Share Repurchases) (Det

Equity (Share Repurchases) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity [Abstract]
Number of shares repurchased	0	9	0	23
Cash paid for shares repurchased	$ 0	$ 500	$ 0	$ 1,385
Average cost per share	$ 0	$ 57.18	$ 0	$ 60.75

Segment Information (Additional

Segment Information (Additional Information) (Detail)	6 Months Ended
	Jun. 30, 2020Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information (Income Fro

Segment Information (Income From Operations Attributable To Operating Segments) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Sales and other operating revenues		$ 15,024	$ 33,529	$ 40,239	$ 61,782
Income from operations		981	2,042	(10,836)	2,711
Depreciation and amortization		935	886	1,897	1,805
Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		3,004	6,686	7,865	12,336
Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		18,028	40,215	48,104	74,118
Income from operations		(256)	2,277	546	3,021
Depreciation and amortization	[1]	895	859	1,812	1,719
Capital expenditures and investments	[2]	762	1,364	1,771	2,654
Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues		9,441	23,654	26,969	43,574
Refining & Marketing | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		1,834	5,466	5,451	9,882
Refining & Marketing | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		11,275	29,120	32,420	53,456
Income from operations		(1,619)	906	(2,241)	572
Depreciation and amortization		433	411	880	838
Capital expenditures and investments		263	430	722	824
Retail
Segment Reporting Information [Line Items]
Sales and other operating revenues		4,778	8,944	11,547	16,320
Retail | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		1	2	3	4
Retail | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		4,779	8,946	11,550	16,324
Income from operations		494	493	1,013	663
Depreciation and amortization		132	130	257	256
Capital expenditures and investments		74	120	150	193
Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues		805	931	1,723	1,888
Midstream | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		1,169	1,218	2,411	2,450
Midstream | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		1,974	2,149	4,134	4,338
Income from operations		869	878	1,774	1,786
Depreciation and amortization		330	318	675	625
Capital expenditures and investments		425	814	899	1,637
Reportable Segment
Segment Reporting Information [Line Items]
Sales and other operating revenues	[3]	$ 15,024	$ 33,529	$ 40,239	$ 61,782
[1]	Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other items not allocated to segments.
[2]	Includes changes in capital expenditure accruals and investments in affiliates. See reconciliation from segment totals to MPC consolidated total capital expenditures below.
[3]	Includes related party sales. See Note 6 for additional information.

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, 2020		Jun. 30, 2019	Jun. 30, 2020		Jun. 30, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		$ 981		$ 2,042	$ (10,836)		$ 2,711
Impairments		25			9,162
LCM inventory valuation adjustment		(1,480)		0	1,740		0
Net interest and other financial costs		345		322	683		628
Income before income taxes		636		1,720	(11,519)		2,083
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		(256)		2,277	546		3,021
Corporate
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations	[1]	(188)		(179)	(415)		(370)
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Equity method investment restructuring gain		0		0	0		207	[2]
Transaction-related costs	[3]	(30)		(34)	(65)		(125)
Litigation		0		(22)	0		(22)
Impairments		(25)	[4]	0	(9,162)	[4]	0
LCM inventory valuation adjustment		$ 1,480	[5]	$ 0	$ (1,740)	[5]	$ 0
[1]	Corporate consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment.
[2]	Includes gain related to Capline Pipeline Company LLC (“Capline LLC”). See Note 13 .
[3]	2020 includes costs incurred in connection with the Speedway separation and Midstream strategic review. 2019 includes employee severance, retention and other costs related to the acquisition of Andeavor.
[4]	Includes goodwill impairment, impairment of equity method investments and impairment of long lived assets. See Note 4
[5]	See Note 12 .

Segment Information (Reconcil_2

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Plus items not allocated to segments:
Capital expenditures	[1]	$ 593	$ 1,132	$ 1,489	$ 2,138
Operating Segments
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments	[2]	762	1,364	1,771	2,654
Less investments in equity method investees		214	270	383	595
Corporate
Plus items not allocated to segments:
Corporate		18	4	45	14
Capitalized interest		$ 27	$ 34	$ 56	$ 65
[1]	Includes changes in capital expenditure accruals. See Note 19 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2020 and 2019 as reported in the consolidated statements of cash flows.
[2]	Includes changes in capital expenditure accruals and investments in affiliates. See reconciliation from segment totals to MPC consolidated total capital expenditures below.

Net Interest and Other Financ_3

Net Interest and Other Financial Costs (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Income and Expenses [Abstract]
Interest income		$ (2)	$ (9)	$ (8)	$ (18)
Interest expense		373	350	730	690
Interest capitalized		(35)	(35)	(71)	(67)
Pension and other postretirement non-service costs	[1]	0	3	(3)	0
Other financial costs		9	13	35	23
Net interest and other financial costs		$ 345	$ 322	$ 683	$ 628
[1]	See Note 21 .

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
State and local income taxes, net of federal income tax effects	$ 33	$ 45	$ (167)	$ 88
CARES Act legislation	102	0	(309)	0
Provision (benefit) for income taxes	$ 360	$ 353	$ (1,577)	$ 457
Effective income tax rate, percent	57.00%		14.00%
Federal statutory income tax rate, percent	21.00%
Unrecognized benefits	$ 25		$ 25
Other noncurrent assets
Income tax receivable, noncurrent	$ 1,100		$ 1,100

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Tax Rate) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Tax computed at statutory rate	$ 133	$ 361	$ (2,419)	$ 437
State and local income taxes, net of federal income tax effects	33	45	(167)	88
Goodwill impairment	0	0	1,156	0
Noncontrolling interests	81	(68)	150	(83)
CARES Act legislation	102	0	(309)	0
Other	11	15	12	15
Income Tax Expense (Benefit)	$ 360	$ 353	$ (1,577)	$ 457

Income Taxes (Out of Period Adj

Income Taxes (Out of Period Adjustment) (Detail) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Provision (benefit) for income taxes	$ 360	$ 353		$ (1,577)	$ 457
Andeavor | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Provision (benefit) for income taxes			$ 36

Inventories (Summary of Invento

Inventories (Summary of Inventories) (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Crude oil	$ 3,163		$ 3,472
Refined products	5,397		5,548
Materials and supplies	1,028		996
Merchandise	238		227
Inventories before LCM inventory valuation reserve	9,826		10,243
LCM inventory valuation reserve	(1,740)	$ (3,220)	0
Total	$ 8,086		$ 10,243

Inventories (Additional Informa

Inventories (Additional Information) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventory, LIFO Reserve	$ 1,740	$ 1,740	$ 3,220	$ 0
Inventory, LIFO reserve, effect on income, net	$ 1,480
Impact on income as a result of LIFO liquidations		$ 0

Equity Method Investments (Capl

Equity Method Investments (Capline LLC) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019		Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Fair value of assets acquired	$ 0	$ 350	[1]
Capline Pipeline LLC
Schedule of Equity Method Investments [Line Items]
Undivided joint interest, ownership percentage				33.00%
Ownership percentage				33.00%
Contribution of net assets		143
Fair value of assets acquired		350
Equity method investment restructuring gain		$ 207
[1]	2019 includes the recognition of the Capline LLC equity method investment. See Note 13

Property, Plant and Equipment_2

Property, Plant and Equipment (Summary of Property, Plant And Equipment) (Detail) - USD ($) $ in Millions	Jun. 30, 2020		Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 66,004		$ 64,623
Less accumulated depreciation	20,979	[1]	19,008
Property, plant and equipment, net	45,025		45,615
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	29,781		29,037
Operating Segments | Retail
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,199		7,104
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	27,696		27,193
Corporate
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,328		$ 1,289
[1]	The June 30, 2020 balance includes property, plant and equipment impairment charges recorded during 2020. See Note 4 for additional information.

Fair Value Measurements (Assets

Fair Value Measurements (Assets and Liabilities Accounted for at Fair Value on Recurring Basis) (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash collateral netted with derivative liabilities		$ 98	$ 51
Fair Value, Measurements, Recurring | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - netting and collateral	[1]	(260)	(55)
Commodity derivative instruments, assets - net carrying value on balance sheet	[2]	3	8
Commodity derivative instruments, assets - collateral pledged not offset		46	73
Commodity derivative instruments, liabilities - netting and collateral	[1]	(358)	(106)
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]	51	60
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]
Commodity derivative instruments, assets - gross		255	57
Commodity derivative instruments, liabilities - gross		350	95
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]
Commodity derivative instruments, assets - gross		8	6
Commodity derivative instruments, liabilities - gross		8	11
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]
Commodity derivative instruments, assets - gross		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		$ 51	$ 60
[1]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of June 30, 2020 , cash collateral of $98 million was netted with the mark-to-market derivative liabilities. As of December 31, 2019 , cash collateral of $51 million was netted with mark-to-market derivative liabilities.
[2]	We have no derivative contracts that are subject to master netting arrangements reflected gross on the balance sheet.

Fair Value Measurements (Recurr

Fair Value Measurements (Recurring Narrative) (Detail)	6 Months Ended
	Jun. 30, 2020USD ($)$ / gal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Average forward price | $ / gal	0.53
Embedded derivatives in commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative renewal term	5 years
Level 3 | Commodity derivatives | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	0.38
Level 3 | Commodity derivatives | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	0.92
Level 3 | Embedded derivatives in commodity contracts
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%

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 45	$ 65	$ 60	$ 61
Unrealized and realized losses included in net income	7	1	(7)	7
Settlements of derivative instruments	(1)	(1)	(2)	(3)
Ending balance	$ 51	$ 65	$ 51	$ 65

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period:	$ 6	$ 2	$ (7)	$ 5

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Values - Reported) (Detail) - USD ($) $ in Billions	Jun. 30, 2020	Dec. 31, 2019
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 33.6	$ 30.1
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 31.6	$ 28.3

Derivatives (Classification of

Derivatives (Classification of Gross Fair Values of Derivative Instruments, Excluding Cash Collateral) (Detail) - Commodity derivatives - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Other current assets
Derivatives, Fair Value [Line Items]
Asset		$ 263	$ 63
Liability		358	106
Other current liabilities(a)
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	3	5
Deferred credits and other liabilities
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	$ 48	$ 55
[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, 2020bblgal
Crude oil
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	94.30%
Crude oil | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	46,032	[1]
Crude oil | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	6,425
Crude oil | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	43,019	[1]
Crude oil | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	2,875
Refined products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	85.30%
Refined products | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	24,489	[1]
Refined products | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	1,525
Refined products | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	18,100	[1]
Refined products | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	225
Blending products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	86.00%
Blending products | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	1,067	[1]
Blending products | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	2,842	[1]
[1]	Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 6,425 long and 2,875 short; Refined products - 1,525 long and 225 short

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (112)	$ 18	$ 103	$ (82)
Sales and other operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	(7)	3	77	(17)
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (105)	$ 15	$ 26	$ (65)

Debt (Outstanding Borrowings) (

Debt (Outstanding Borrowings) (Detail) - USD ($) $ in Millions		Jun. 30, 2020	Apr. 27, 2020	Dec. 31, 2019
Total debt		$ 32,605		$ 29,282
Unamortized debt issuance costs		(143)		(134)
Unamortized (discount) premium, net		(296)		(310)
Amounts due within one year		(1,715)		(711)
Total long-term debt due after one year		30,451		28,127
MPLX bank revolving credit facility
Long-term line of credit	[1]	825
Senior notes
Long-term debt, gross			$ 2,500
Marathon Petroleum Corporation:
Notes payable		10		10
Marathon Petroleum Corporation: | Senior notes
Long-term debt, gross		10,974		8,474
Marathon Petroleum Corporation: | Finance lease
Finance lease liabilities		683		679
MPLX LP: | MPLX bank revolving credit facility
Long-term line of credit		825		0
MPLX LP: | Line of credit | MPLX term loan facility
Long-term debt, gross		1,000		1,000
MPLX LP: | Senior notes
Long-term debt, gross		19,100		19,100
MPLX LP: | Finance lease
Finance lease liabilities		$ 13		$ 19
[1]	Borrowed $2.5 billion at an average interest rate of 1.53 percent and repaid $1.675 billion during the six months ended June 30, 2020

Debt (Available Capacity under

Debt (Available Capacity under our Facilities) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
MPC 364-day bank revolving credit facility due September 2020
Debt Instrument [Line Items]
Total Capacity	$ 1,000
Outstanding Borrowings	0
Outstanding Letters of Credit	0
Available Capacity	$ 1,000
Weighted Average Interest Rate	0.00%
MPC 364-day bank revolving credit facility due April 2021
Debt Instrument [Line Items]
Total Capacity	$ 1,000
Outstanding Borrowings	0
Outstanding Letters of Credit	0
Available Capacity	$ 1,000
Weighted Average Interest Rate	0.00%
MPC bank revolving credit facility
Debt Instrument [Line Items]
Total Capacity	$ 5,000
Outstanding Borrowings	0	[1]
Outstanding Letters of Credit	1
Available Capacity	$ 4,999
Weighted Average Interest Rate	0.00%
Borrowings	$ 3,500
Repayments	3,500
MPC trade receivables securitization facility
Debt Instrument [Line Items]
Total Capacity	705
Outstanding Borrowings	0	[2]
Outstanding Letters of Credit	0
Available Capacity	$ 705
Weighted Average Interest Rate	0.00%
Borrowings	$ 1,175
Repayments	1,175
Maximum borrowing capacity	750
MPLX bank revolving credit facility
Debt Instrument [Line Items]
Total Capacity	3,500
Outstanding Borrowings	825	[3]
Outstanding Letters of Credit	0
Available Capacity	$ 2,675
Weighted Average Interest Rate	1.36%
Borrowings	$ 2,500
Repayments	$ 1,675
Weighted average interest rate over time	1.53%
[1]	Borrowed $3.5 billion and repaid $3.5 billion during the six months ended June 30, 2020.
[2]	Borrowed $1.175 billion and repaid $1.175 billion during the six months ended June 30, 2020
[3]	Borrowed $2.5 billion at an average interest rate of 1.53 percent and repaid $1.675 billion during the six months ended June 30, 2020

Debt (Additional MPC 364-Day Ba

Debt (Additional MPC 364-Day Bank Revolving Credit Facility) (Details) $ in Billions	Apr. 27, 2020USD ($)
Marathon Petroleum Corporation: | MPC 364-day bank revolving credit facility due April 2021
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1

Debt (MPC Senior Notes Issuance

Debt (MPC Senior Notes Issuance) (Details) - Senior notes $ in Millions	Apr. 27, 2020USD ($)
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,500
Senior notes due May 2023
Debt Instrument [Line Items]
Long-term debt, gross	1,250
Senior notes due May 2025
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,250

Revenue (Disaggregated by Produ

Revenue (Disaggregated by Product Line) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Sales and other operating revenues	$ 15,024	$ 33,529	$ 40,239	$ 61,782
Refining & Marketing
Sales and other operating revenues	9,441	23,654	26,969	43,574
Retail
Sales and other operating revenues	4,778	8,944	11,547	16,320
Midstream
Sales and other operating revenues	805	931	1,723	1,888
Refined products
Sales and other operating revenues	11,621	29,714	33,618	54,627
Refined products | Refining & Marketing
Sales and other operating revenues	8,341	22,221	24,880	40,971
Refined products | Retail
Sales and other operating revenues	3,160	7,303	8,449	13,250
Refined products | Midstream
Sales and other operating revenues	120	190	289	406
Merchandise
Sales and other operating revenues	1,599	1,614	3,056	3,024
Merchandise | Refining & Marketing
Sales and other operating revenues	0	1	1	2
Merchandise | Retail
Sales and other operating revenues	1,599	1,613	3,055	3,022
Merchandise | Midstream
Sales and other operating revenues	0	0	0	0
Crude oil
Sales and other operating revenues	1,003	1,310	1,878	2,381
Crude oil | Refining & Marketing
Sales and other operating revenues	1,003	1,310	1,878	2,381
Crude oil | Retail
Sales and other operating revenues	0	0	0	0
Crude oil | Midstream
Sales and other operating revenues	0	0	0	0
Midstream services and other
Sales and other operating revenues	801	891	1,687	1,750
Midstream services and other | Refining & Marketing
Sales and other operating revenues	97	122	210	220
Midstream services and other | Retail
Sales and other operating revenues	19	28	43	48
Midstream services and other | Midstream
Sales and other operating revenues	$ 685	$ 741	$ 1,434	$ 1,482

Revenue (Details)

Revenue (Details) $ in Millions	Jun. 30, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Matching buy/sell receivables	$ 1,010

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Summary of Supplemental Cash Flow Information) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 601	$ 579
Net income taxes paid to taxing authorities	6	362
Non-cash investing and financing activities:
Contribution of net assets	0	143	[1]
Fair value of assets acquired	$ 0	$ 350	[2]
[1]	2019 includes the contribution of net assets to Capline LLC. See Note 13 .
[2]	2019 includes the recognition of the Capline LLC equity method investment. See Note 13

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information (Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents		$ 1,091	$ 1,527
Restricted cash	[1]	2	2
Cash, cash equivalents and restricted cash		$ 1,093	$ 1,529	$ 1,249	$ 1,725
[1]	The restricted cash balance is included within other current assets on the consolidated balance sheets

Supplemental Cash Flow Inform_5

Supplemental Cash Flow Information (Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Supplemental Cash Flow Elements [Abstract]
Additions to property, plant and equipment per the consolidated statements of cash flows				$ 1,910	$ 2,419
Decrease in capital accruals				(421)	(281)
Capital expenditures	[1]	$ 593	$ 1,132	$ 1,489	$ 2,138
[1]	Includes changes in capital expenditure accruals. See Note 19 for a reconciliation of total capital expenditures to additions to property, plant and equipment for the six months ended June 30, 2020 and 2019 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, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ (320)		$ (144)	$ (320)	$ (144)
Other comprehensive income (loss), before reclassifications, net of tax						(12)	(6)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit						(23)	(23)
Amortization - actuarial loss						19	10
Amortization - settlement loss						1	2
Other						(3)	(3)
Tax effect						2	3
Other comprehensive income (loss)		$ (10)	(6)	$ (10)	(7)	(16)	(17)
Ending balance		(336)		(161)		(336)	(161)
Other comprehensive income (loss) before reclassifications, tax						4	3
Accumulated Defined Benefit Plans Adjustment | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(212)		(132)	(212)	(132)
Other comprehensive income (loss), before reclassifications, net of tax						(10)	(7)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]					(23)	(23)
Amortization - actuarial loss	[1]					18	11
Amortization - settlement loss	[1]					1	2
Tax effect						1	2
Other comprehensive income (loss)						(13)	(15)
Ending balance		(225)		(147)		(225)	(147)
Accumulated Defined Benefit Plans Adjustment | Other Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(116)		(23)	(116)	(23)
Other comprehensive income (loss), before reclassifications, net of tax						(2)	1
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]					0	0
Amortization - actuarial loss	[1]					1	(1)
Amortization - settlement loss						0	0
Tax effect						0	0
Other comprehensive income (loss)						(1)	0
Ending balance		(117)		(23)		(117)	(23)
Gain on Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			1		2	1	2
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		2		1	2
Workers Compensation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ 7		$ 9	7	9
Other comprehensive income (loss), before reclassifications, net of tax						0	0
Amounts reclassified from accumulated other comprehensive loss:
Other						(3)	(3)
Tax effect						1	1
Other comprehensive income (loss)						(2)	(2)
Ending balance		$ 5		$ 7		$ 5	$ 7
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 21 .

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 83	$ 60	$ 152	$ 118
Interest cost	24	27	49	55
Expected return on plan assets	(32)	(31)	(66)	(63)
Amortization – prior service credit	(12)	(12)	(23)	(23)
Amortization – actuarial loss	10	7	18	11
Amortization - settlement loss	1	2	1	2
Net periodic benefit cost	74	53	131	100
Other Benefits
Components of net periodic benefit cost:
Service cost	9	8	18	16
Interest cost	9	10	17	19
Expected return on plan assets	0	0	0	0
Amortization – prior service credit	0	0	0	0
Amortization – actuarial loss	0	(1)	1	(1)
Amortization - settlement loss	0	0	0	0
Net periodic benefit cost	$ 18	$ 17	$ 36	$ 34

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits (Additional Information) (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 3
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	40
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	$ 20

Commitments and Contingencies (

Commitments and Contingencies (Detail)	6 Months Ended
	Jun. 30, 2020
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, inestimable loss	For matters for which we have not recorded a liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings.

Commitments and Contingencies_2

Commitments and Contingencies (Environmental Matters) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Accrued liabilities for remediation	$ 412	$ 433
Receivables for recoverable costs	$ 28	$ 29

Commitments and Contingencies_3

Commitments and Contingencies (Other Legal Proceedings) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Loss contingency, damages sought, value	$ 187

(Guarantees) (Details)

(Guarantees) (Details) $ in Millions	Jun. 30, 2020USD ($)
Other Guarantees
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 104
LOOP and LOCAP LLC | Guarantee of Indebtedness of Others | Financial Guarantee
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 171
Gray Oak Pipeline
Loss Contingencies [Line Items]
Ownership percentage	25.00%
Gray Oak Pipeline | Guarantee of Indebtedness of Others | Financial Guarantee
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 345
Maximum borrowing capacity	$ 1,430
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	$ 125
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	$ 118

Commitments and Contingencies_4

Commitments and Contingencies (Contractual Commitments and Contingencies) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	$ 678

Subsequent Events (Agreement to

Subsequent Events (Agreement to sell our Speedway business) (Details) $ in Billions	Aug. 02, 2020USD ($)
Discontinued Operations, Disposed of by Sale [Member] | Speedway | Subsequent Event
Subsequent Event [Line Items]
Consideration for sale of Speedway	$ 21

Subsequent Events (Redemption o

Subsequent Events (Redemption of business from MPLX) (Details) - MPLX LP - Subsequent Event $ in Millions	Jul. 31, 2020USD ($)shares
Subsequent Event [Line Items]
Stock redeemed or called during period, shares | shares	18,582,088
Stock redeemed or called during period, value | $	$ 340