Marathon Petroleum (MPC) 10-Q 7 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 01, 2020
Document And Entity Information [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)	Q1
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-35054
Entity Registrant Name	Marathon Petroleum Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-1284632
Entity Address, Address Line One	539 South Main Street
Entity Address, City or Town	Findlay
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45840-3229
City Area Code	419
Local Phone Number	422-2121
Title of 12(b) Security	Common Stock, par value $.01
Trading Symbol	MPC
Security Exchange Name	NYSE
Entity 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		650,260,897

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
Revenues and other income:
Sales and other operating revenues	$ 25,215		$ 28,253
Income (loss) from equity method investments	(1,210)	[1],[2]	99
Net gain on disposal of assets	4		214
Other income	71		35
Total revenues and other income	24,080		28,601
Costs and expenses:
Cost of revenues (excludes items below)	22,821		25,960
Inventory market valuation adjustment	3,220		0
Impairment expense	7,822		0
Depreciation and amortization	962		919
Selling, general and administrative expenses	821		867
Other taxes	251		186
Total costs and expenses	35,897		27,932
Income (loss) from operations	(11,817)		669
Net interest and other financial costs	338		306
Income (loss) before income taxes	(12,155)		363
Provision (benefit) for income taxes	(1,937)		104
Net income (loss)	(10,218)		259
Less net income (loss) attributable to:
Redeemable noncontrolling interest	20		20
Noncontrolling interests	(1,004)		246
Net loss attributable to MPC	$ (9,234)		$ (7)
Basic:
Net loss attributable to MPC per share	$ (14.25)		$ (0.01)
Weighted average shares outstanding (in shares)	648		673
Diluted:
Net loss attributable to MPC per share	$ (14.25)		$ (0.01)
Weighted average shares outstanding (in shares)	648		673
[1]	The 2020 period includes $1,315 million of impairment expense. See Note 4 for further information.
[2]	The 2020 period 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
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (10,218)	$ 259
Defined benefit plans:
Actuarial changes, net of tax of $1 and $6, respectively	4	(3)
Prior service credit, net of tax of ($3) and ($8), respectively	(9)	(3)
Other, net of tax of $0 and $0, respectively	(1)	(1)
Other comprehensive loss	(6)	(7)
Comprehensive income (loss)	(10,224)	252
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	20	20
Noncontrolling interests	(1,004)	246
Comprehensive loss attributable to MPC	$ (9,240)	$ (14)

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Actuarial changes, tax	$ 1	$ 6
Prior service credit, tax	(3)	(8)
Other, tax	$ 0	$ 0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 1,690	$ 1,527
Receivables, less allowance for doubtful accounts of $18 and $17, respectively	5,583	7,479
Inventories	7,445	10,243
Other current assets	975	921
Total current assets	15,693	20,170
Equity method investments	5,656	6,898
Property, plant and equipment, net	45,333	45,615
Goodwill	12,710	20,040
Right of use assets	2,562	2,459
Other noncurrent assets	4,363	3,374
Total assets	86,317	98,556
Current liabilities:
Accounts payable	8,106	11,623
Payroll and benefits payable	1,107	1,126
Accrued taxes	1,098	1,186
Debt due within one year	1,710	711
Operating lease liabilities	630	604
Other current liabilities	918	897
Total current liabilities	13,569	16,147
Long-term debt	29,899	28,127
Deferred income taxes	5,772	6,392
Defined benefit postretirement plan obligations	1,703	1,643
Long-term operating lease liabilities	1,949	1,875
Deferred credits and other liabilities	1,229	1,265
Total liabilities	54,121	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	(15,145)	(15,143)
Additional paid-in capital	33,169	33,157
Retained earnings	6,380	15,990
Accumulated other comprehensive loss	(326)	(320)
Total MPC stockholders’ equity	24,088	33,694
Noncontrolling interests	7,140	8,445
Total equity	31,228	42,139
Total liabilities, redeemable noncontrolling interest and equity	$ 86,317	$ 98,556

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Mar. 31, 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	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
Operating activities:
Net income (loss)	$ (10,218)		$ 259
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization of deferred financing costs and debt discount	14		0
Impairment expense	7,822		0
Depreciation and amortization	962		919
Inventory market valuation adjustment	3,220		0
Pension and other postretirement benefits, net	55		52
Deferred income taxes	(625)		127
Net gain on disposal of assets	(4)		(214)
(Income) loss from equity method investments	1,210	[1],[2]	(99)
Distributions from equity method investments	175		148
Changes in income tax receivable	(1,335)		(19)
Changes in the fair value of derivative instruments	(47)		29
Changes in operating assets and liabilities, net of effects of businesses acquired:
Current receivables	1,899		(1,018)
Inventories	(422)		(4)
Current accounts payable and accrued liabilities	(3,453)		1,483
Right of use assets and operating lease liabilities, net	(4)		(1)
All other, net	(17)		(39)
Net cash provided by (used in) operating activities	(768)		1,623
Investing activities:
Additions to property, plant and equipment	(1,062)		(1,241)
Disposal of assets	56		24
Investments – acquisitions, loans and contributions	(169)		(325)
Investments - redemptions, repayments and return of capital	77		2
All other, net	10		20
Net cash used in investing activities	(1,088)		(1,520)
Financing activities:
Long-term debt – borrowings	4,250		2,604
Long-term debt – repayments	(1,521)		(2,031)
Issuance of common stock	4		2
Common stock repurchased	0		(885)
Dividends paid	(377)		(354)
Distributions to noncontrolling interests	(320)		(325)
Contributions from noncontrolling interests	0		95
All other, net	(15)		(26)
Net cash provided by (used in) financing activities	2,021		(920)
Net increase (decrease) in cash, cash equivalents and restricted cash	165		(817)
Cash, cash equivalents and restricted cash at beginning of period	1,529		1,725
Cash, cash equivalents and restricted cash at end of period	$ 1,694		$ 908
[1]	The 2020 period includes $1,315 million of impairment expense. See Note 4 for further information.
[2]	The 2020 period includes $1,315 million of impairment expense. See Note 4

Consolidated Statements of Equi

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, 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						0
Ending balance at Mar. 31, 2020	$ 31,228	$ 10	$ (15,145)	$ 33,169	$ 6,380	$ (326)	$ 7,140

Consolidated Statement of Equit

Consolidated Statement of Equity - 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
Beginning balance at Dec. 31, 2019	978	978
Number of common shares issued - stock compensation		1
Ending balance at Mar. 31, 2020	979	979

Consolidated Statements of Eq_2

Consolidated Statements of Equity - Shares of Treasury Stock - shares shares in Millions	Total	Treasury Stock
Beginning balance at Dec. 31, 2018		(295)
Number of shares repurchased	(14)	(14)
Number of shares returned - stock compensation		0
Ending balance at Mar. 31, 2019		(309)
Beginning balance at Dec. 31, 2019	(329)	(329)
Number of shares repurchased	0
Number of shares returned - stock compensation		0
Ending balance at Mar. 31, 2020	(329)	(329)

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interest - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Temporary Equity [Abstract]
Beginning balance	$ 968	$ 1,004
Net income attributable to redeemable noncontrolling interest	20	20
Distributions to noncontrolling interests	(20)	(20)
Ending balance	$ 968	$ 1,004

Consolidated Statements of Eq_3

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

Description of the Business and

Description of the Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business and Basis of Presentation	DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION Description of the Business We are a leading, integrated, downstream energy company headquartered in Findlay, Ohio. We operate the nation's largest refining system with more than 3 million barrels per day of crude oil capacity across 16 refineries. 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 6,900 branded outlets. Our retail operations own and operate approximately 3,880 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. On October 31, 2019, we announced our intention to separate our retail transportation fuel and convenience store business, which is operated primarily under the Speedway brand, into an independent, publicly traded company through a tax-free distribution to MPC shareholders of publicly traded stock in the new independent retail transportation fuel and convenience store company. This transaction is targeted to be completed in the fourth quarter of 2020, however timing could change given the COVID-19 related impacts to the business environment and access to capital markets. This transaction is subject to market, regulatory and certain other conditions, including final approval by the MPC Board of Directors, receipt of customary assurances regarding the intended tax-free nature of the transaction, and the effectiveness of a registration statement to be filed with the SEC. The Speedway business is currently a reporting unit within our Retail segment. MPC will retain its direct dealer business, which is also included in the Retail segment as currently reported. Subsequent to the completion of the separation, the historical results of the Speedway business will be presented as discontinued operations in our consolidated financial statements. 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 months ended March 31, 2020 are not necessarily indicative of the results to be expected for the full year.

Accounting Standards

Accounting Standards	3 Months Ended
	Mar. 31, 2020
New Accounting Pronouncements and Changes in Accounting Principles [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 March 31, 2020 , we reported $5,583 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 ASU during the first three 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
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	3 Months Ended
	Mar. 31, 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 March 31, 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: Three Months Ended (In millions) 2020 2019 Increase due to the issuance of MPLX & ANDX common units $ 2 $ 4 Tax impact (7 ) (1 ) Increase (decrease) in MPC's additional paid-in capital, net of tax $ (5 ) $ 3

Impairments

Impairments	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Impairments	IMPAIRMENTS The recent 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 significantly reduced global economic activity and resulted in airlines dramatically cutting back on flights and a decrease in motor vehicle use at a time when seasonal driving patterns typically result in an increase of consumer demand for gasoline. In addition, recent global geopolitical events and macroeconomic conditions have exacerbated the decline in crude oil prices and have contributed to an increase in crude oil price volatility. The decrease in the demand for refined petroleum products coupled with the decline in the price of crude oil has resulted in a significant decrease in the price of the refined petroleum products we produce and sell. 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 assessments to identify any potential impairments of the carrying values of our assets. During the first quarter of 2020, we recognized impairment charges related to goodwill, equity method investments and long-lived assets (including intangibles). The table below provides information related to the impairments recognized during the first quarter of 2020 and the location of these impairments within the consolidated statements of income. (In millions) Income Statement Line Impairment Goodwill Impairment expense $ 7,330 Equity method investments Income (loss) from equity method investments 1,315 Long-lived assets Impairment expense 492 Total impairments $ 9,137 Goodwill During the first quarter of 2020, we recorded an impairment of goodwill. 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 guidance related to the slowing of drilling activity, which has reduced production growth forecasts from MPLX’s producer customers. The fair value of the reporting units for the 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 March 31, 2020 $ — $ 4,951 $ 7,759 $ 12,710 Equity Method Investments During the first quarter of 2020, we recorded equity method investment impairment charges, 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 as a result of significant impacts to the Refining & Marketing segment forecasted 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. All other refinery asset groups undiscounted estimated pretax cash flows exceeded the carrying value by at least 21 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. 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 additional refinery asset groups exceed the undiscounted estimated pretax cash flows of their refinery asset groups, which would result in future impairment charges. 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 to impairment expense on the consolidated statements of income. The fair value measurements for the Gallup refinery assets represent Level 3 measurements. 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 impacts to forecasted 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	3 Months Ended
	Mar. 31, 2020
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [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) March 31, December 31, Assets Cash and cash equivalents $ 57 $ 15 Receivables, less allowance for doubtful accounts 544 615 Inventories 105 110 Other current assets 45 110 Equity method investments 3,992 5,275 Property, plant and equipment, net 22,030 22,174 Goodwill 7,722 9,536 Right of use assets 352 365 Other noncurrent assets 1,105 1,323 Liabilities Accounts payable $ 521 $ 744 Payroll and benefits payable 1 5 Accrued taxes 72 80 Debt due within one year 4 9 Operating lease liabilities 67 66 Other current liabilities 268 259 Long-term debt 20,467 19,704 Deferred income taxes 11 12 Long-term operating lease liabilities 284 302 Deferred credits and other liabilities 422 409

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS Transactions with related parties were as follows: Three Months Ended (In millions) 2020 2019 Sales to related parties $ 165 $ 186 Purchases from related parties 195 204 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.

Loss per Share

Loss per Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Loss per Share	LOSS PER SHARE We compute basic earnings (loss) per share by dividing net income (loss) attributable to MPC less income allocated to participating securities by the weighted average number of shares of common stock outstanding. Since MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities, we have calculated our earnings (loss) per share using the two-class method. Diluted income (loss) per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive. Three Months Ended (In millions, except per share data) 2020 2019 Basic loss per share: Allocation of loss: Net loss attributable to MPC $ (9,234 ) $ (7 ) Income allocated to participating securities — — Loss available to common stockholders – basic $ (9,234 ) $ (7 ) Weighted average common shares outstanding 648 673 Basic loss per share $ (14.25 ) $ (0.01 ) Diluted loss per share: Allocation of loss: Net loss attributable to MPC $ (9,234 ) $ (7 ) Income allocated to participating securities — — Loss available to common stockholders – diluted $ (9,234 ) $ (7 ) Weighted average common shares outstanding 648 673 Effect of dilutive securities — — Weighted average common shares, including dilutive effect 648 673 Diluted loss per share $ (14.25 ) $ (0.01 ) The following table summarizes the shares that were anti-dilutive and, therefore, were excluded from the diluted share calculation. Three Months Ended (In millions) 2020 2019 Shares issuable under stock-based compensation plans 10 7

Equity

Equity	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Equity	EQUITY As of March 31, 2020 , we had $2.96 billion of remaining share repurchase authorizations from our board of directors. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, tender offers, accelerated share repurchases or open market solicitations for shares, some of which may be effected through Rule 10b5-1 plans. The timing and amount of future repurchases, 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 (In millions, except per share data) 2020 2019 Number of shares repurchased — 14 Cash paid for shares repurchased $ — $ 885 Average cost per share $ — $ 62.98

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 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 16 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 March 31, 2020 Revenues: Third party (a) $ 17,528 $ 6,769 $ 918 $ 25,215 Intersegment 3,617 2 1,242 4,861 Segment revenues $ 21,145 $ 6,771 $ 2,160 $ 30,076 Segment income (loss) from operations $ (622 ) $ 519 $ 905 $ 802 Supplemental Data Depreciation and amortization (b) $ 447 $ 125 $ 345 $ 917 Capital expenditures and investments (c) 459 76 474 1,009 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended March 31, 2019 Revenues: Third party (a) $ 19,920 $ 7,376 $ 957 $ 28,253 Intersegment 4,416 2 1,232 5,650 Segment revenues $ 24,336 $ 7,378 $ 2,189 $ 33,903 Segment income (loss) from operations $ (334 ) $ 170 $ 908 $ 744 Supplemental Data Depreciation and amortization (b) $ 427 $ 126 $ 307 $ 860 Capital expenditures and investments (c) 394 73 823 1,290 (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 unallocated items and are included in items not allocated to segments in the reconciliation below. (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 (In millions) 2020 2019 Segment income from operations $ 802 $ 744 Items not allocated to segments: Corporate and other unallocated items (a) (227 ) (191 ) Equity method investment restructuring gain (b) — 207 Transaction-related costs (c) (35 ) (91 ) Impairments (d) (9,137 ) — Inventory market valuation adjustment (e) (3,220 ) — Income (loss) from operations (11,817 ) 669 Net interest and other financial costs 338 306 Income (loss) before income taxes $ (12,155 ) $ 363 (a) Corporate and other unallocated items consist primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Retail segments. (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 (In millions) 2020 2019 Segment capital expenditures and investments $ 1,009 $ 1,290 Less investments in equity method investees 169 325 Plus items not allocated to segments: Corporate 27 10 Capitalized interest 29 31 Total capital expenditures (a) $ 896 $ 1,006 (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 three months ended March 31, 2020 and 2019 as reported in the consolidated statements of cash flows.

Net Interest and Other Financia

Net Interest and Other Financial Costs	3 Months Ended
	Mar. 31, 2020
Other Income and Expenses [Abstract]
Net Interest and Other Financial Costs	NET INTEREST AND OTHER FINANCIAL COSTS Net interest and other financial costs were as follows: Three Months Ended (In millions) 2020 2019 Interest income $ (6 ) $ (9 ) Interest expense 357 340 Interest capitalized (36 ) (32 ) Pension and other postretirement non-service credits (a) (3 ) (3 ) Other financial costs 26 10 Net interest and other financial costs $ 338 $ 306 (a) See Note 21 .

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 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 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: • Reducing 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 $1.9 billion for the three months ended March 31, 2020, of which $411 million was attributable to the expected NOL carryback provided for under the CARES Act. The combined federal, state and foreign income tax rate was 16 percent for the three months ended March 31, 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 a favorable rate effect of the CARES Act legislation. Additionally, our effective tax rate is generally benefited by our noncontrolling interest in MPLX, but this benefit was lower for the three months ended March 31, 2020 compared to the three months ended March 31, 2019 due to impairment charges recorded by MPLX. We recorded an income tax receivable of $1.3 billion in other noncurrent assets to reflect our estimate of the tax benefit we will realize at the time of our 2020 tax return filing which is expected during the second half of 2021. A reconciliation of the federal statutory income tax rate applied to income (loss) before income taxes to the (benefit) provision for income taxes follows: Three Months Ended 2020 2019 Statutory rate applied to income before income taxes 21 % 21 % State and local income taxes, net of federal income tax effects 2 12 Goodwill impairment (10 ) — Noncontrolling interests (1 ) (4 ) CARES Act legislation 3 — Other 1 — Effective tax rate 16 % 29 % 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 March 31, 2020 , we had $27 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	3 Months Ended
	Mar. 31, 2020
Inventory Disclosure [Abstract]
Inventories	INVENTORIES (In millions) March 31, December 31, Crude oil $ 3,717 $ 3,472 Refined products 5,700 5,548 Materials and supplies 1,000 996 Merchandise 248 227 Inventories before LCM inventory valuation reserve 10,665 10,243 LCM inventory valuation reserve (3,220 ) — Total $ 7,445 $ 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 if the LIFO cost basis of these inventories may have to be written down to market values. At March 31, 2020 , market values for these inventories were lower than their LIFO cost basis and, as a result, we recorded an inventory valuation charge of $3.22 billion to value these inventories at the lower of cost or market. Based on movements of refined product prices, future inventory valuation adjustments could have a negative or positive effect to earnings. Such losses are subject to reversal in subsequent periods if prices recover. 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 three months ended March 31, 2020

Equity Method Investments

Equity Method Investments	3 Months Ended
	Mar. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	EQUITY METHOD INVESTMENTS Significant Equity Method Investments Summarized financial information, in the aggregate, for our significant equity method investments on a 100 percent basis were as follows: Three Months Ended (In millions) 2020 2019 Revenues and other income $ 1,072 $ 1,628 Income (loss) from operations (20 ) 336 Net income (loss) (44 ) 314 Capline LLC During the three months ended March 31, 2019, we executed agreements with Capline Pipeline Company LLC (“Capline LLC”) to contribute our 33 percent undivided interest in the Capline pipeline system in exchange for a 33 percent ownership interest in Capline LLC. In connection with our execution of these agreements, Capline LLC initiated a binding open season for southbound service from Patoka, Illinois to St. James, Louisiana or Liberty, Mississippi with an additional origination point at Cushing, Oklahoma. Service from Cushing, Oklahoma is part of a joint tariff with Diamond pipeline. Crude oil service is expected to begin in the first half of 2021. 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	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT (In millions) March 31, December 31, Refining & Marketing $ 29,511 $ 29,037 Retail 7,161 7,104 Midstream 27,490 27,193 Corporate and Other 1,308 1,289 Total 65,470 64,623 Less accumulated depreciation (a) 20,137 19,008 Property, plant and equipment, net $ 45,333 $ 45,615 (a) The March 31, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020. See Note 4 for additional information.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Values—Recurring The following tables present assets and liabilities accounted for at fair value on a recurring basis as of March 31, 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. March 31, 2020 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 754 $ 32 $ — $ (679 ) $ 107 $ 7 Liabilities: Commodity contracts $ 610 $ 19 $ — $ (628 ) $ 1 $ — Embedded derivatives in commodity contracts — — 45 — 45 — 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 March 31, 2020 , cash collateral of $67 million was netted with mark-to-market assets and $16 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 March 31, 2020 used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.26 to $0.68 per gallon with a weighted average of $0.39 per gallon per the current term of the embedded derivative and (2) the probability of renewal of 95 percent for the first five-year term and 83.5 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. Beyond the embedded derivative discussed above, we had no outstanding commodity contracts as of March 31, 2020 . 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 (In millions) 2020 2019 Beginning balance $ 60 $ 61 Unrealized and realized (gains) losses included in net income (14 ) 6 Settlements of derivative instruments (1 ) (2 ) Ending balance $ 45 $ 65 The amount of total (gains) losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: $ (13 ) $ 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 $31.0 billion and $27.7 billion at March 31, 2020 , respectively, and approximately $28.3 billion and $30.1 billion at December 31, 2019 , respectively. These carrying and fair values of our debt exclude the unamortized issuance costs which are netted against our total debt.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 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 March 31, 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) March 31, 2020 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 786 $ 629 Other current liabilities (a) — 2 Deferred credits and other liabilities (a) — 43 (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 March 31, 2020 . Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 94.8% 29,202 46,121 Refined products 84.3% 20,370 16,960 Blending products 100.0% 3,581 3,359 (a) Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 3,840 long and 640 short; Refined products - 2,575 long and 1,775 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 Income Statement Location 2020 2019 Sales and other operating revenues $ 84 $ (20 ) Cost of revenues 131 (80 ) Total $ 215 $ (100 )

Debt

Debt	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Debt	DEBT Our outstanding borrowings at March 31, 2020 and December 31, 2019 consisted of the following: (In millions) March 31, December 31, Marathon Petroleum Corporation: Bank revolving credit facility $ 2,000 $ — Senior notes 8,474 8,474 Notes payable 10 10 Finance lease obligations 692 679 MPLX LP: Bank revolving credit facility 750 — Term loan facility 1,000 1,000 Senior notes 19,100 19,100 Finance lease obligations 14 19 Total debt $ 32,040 $ 29,282 Unamortized debt issuance costs (129 ) (134 ) Unamortized (discount) premium, net (302 ) (310 ) Amounts due within one year (1,710 ) (711 ) Total long-term debt due after one year $ 29,899 $ 28,127 Available Capacity under our Facilities as of March 31, 2020 (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Weighted Average Interest Rate Expiration MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2020 MPC bank revolving credit facility (a) 5,000 2,000 1 2,999 1.89 % October 2023 MPC trade receivables securitization facility (b) 750 — — 750 — July 2021 MPLX bank revolving credit facility (c) 3,500 750 — 2,750 1.94 % July 2024 (a) Borrowed $2 billion on March 30, 2020. (b) Borrowed $925 million and repaid $925 million during the three months ended March 31, 2020 . (c) Borrowed $1.325 billion at an average interest rate of 2.14 percent and repaid $575 million during the three months ended March 31, 2020 .

Revenue

Revenue	3 Months Ended
	Mar. 31, 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 March 31, 2020 Refined products $ 16,539 $ 5,289 $ 169 $ 21,997 Merchandise 1 1,456 — 1,457 Crude oil 875 — — 875 Midstream services and other 113 24 749 886 Sales and other operating revenues $ 17,528 $ 6,769 $ 918 $ 25,215 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended March 31, 2019 Refined products $ 18,750 $ 5,947 $ 216 $ 24,913 Merchandise 1 1,409 — 1,410 Crude oil 1,071 — — 1,071 Midstream services and other 98 20 741 859 Sales and other operating revenues $ 19,920 $ 7,376 $ 957 $ 28,253 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 March 31, 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 March 31, 2020 include matching buy/sell receivables of $2.33 billion

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION Three Months Ended (In millions) 2020 2019 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 303 $ 269 Net income taxes paid to taxing authorities (9 ) 42 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) March 31, December 31, Cash and cash equivalents $ 1,690 $ 1,527 Restricted cash (a) 4 2 Cash, cash equivalents and restricted cash $ 1,694 $ 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: Three Months Ended (In millions) 2020 2019 Additions to property, plant and equipment per the consolidated statements of cash flows $ 1,062 $ 1,241 Decrease in capital accruals (166 ) (235 ) Total capital expenditures $ 896 $ 1,006

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2018 $ (132 ) $ (23 ) $ 2 $ 9 $ (144 ) Other comprehensive loss before reclassifications, net of tax of $0 (1 ) — — — (1 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (11 ) — — — (11 ) – actuarial loss (a) 4 — — — 4 – settlement loss (a) — — — — — Other — — — (1 ) (1 ) Tax effect 2 — — — 2 Other comprehensive loss (6 ) — — (1 ) (7 ) Balance as of March 31, 2019 $ (138 ) $ (23 ) $ 2 $ 8 $ (151 ) (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 ($1) (2 ) (2 ) — — (4 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (11 ) — — — (11 ) – actuarial loss (a) 8 1 — — 9 – settlement loss (a) — — — — — Other — — — (1 ) (1 ) Tax effect 1 — — — 1 Other comprehensive loss (4 ) (1 ) — (1 ) (6 ) Balance as of March 31, 2020 $ (216 ) $ (117 ) $ 1 $ 6 $ (326 ) (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	3 Months Ended
	Mar. 31, 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 March 31, Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Components of net periodic benefit cost: Service cost $ 69 $ 58 $ 9 $ 8 Interest cost 25 28 8 9 Expected return on plan assets (34 ) (32 ) — — Amortization – prior service credit (11 ) (11 ) — — – actuarial loss 8 4 1 — – settlement loss — — — — Net periodic benefit cost $ 57 $ 47 $ 18 $ 17 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 three months ended March 31, 2020 , we made contributions of $3 million to our funded pension plans. Benefit payments related to unfunded pension and other postretirement benefit plans were $6 million and $11 million , respectively, during the three months ended March 31, 2020 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which we have not recorded a liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material. Environmental Matters We are subject to federal, state, local and foreign laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites and certain other locations including presently or formerly owned or operated retail marketing sites. Penalties may be imposed for noncompliance. At March 31, 2020 and December 31, 2019 , accrued liabilities for remediation totaled $418 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 $29 million and $29 million at March 31, 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 Lawsuits 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. At this stage, the ultimate outcome of this litigation remains uncertain, and neither the likelihood of an unfavorable outcome nor the ultimate liability, if any, can be determined, and we are unable to estimate a reasonably possible loss (or range of loss) for this matter. We intend to vigorously defend ourselves in this matter. 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 —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 March 31, 2020 . 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 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 March 31, 2020 , our maximum potential undiscounted payments under the Equity Contribution Agreement for the debt principal totaled $345 million . In connection with MPLX’s 9.19 percent indirect interest in a joint venture 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 ordered the U.S. Army Corps of Engineers, 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. If the permit is vacated pending completion of the EIS and the vacatur is deemed temporary, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes while the pipeline is shutdown and 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 court vacates the permit and such action 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, if any. As of March 31, 2020 , our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement was approximately $230 million . 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 March 31, 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 March 31, 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 $103 million as of March 31, 2020 , which primarily consist of a commitment to contribute cash to an equity method investee for certain catastrophic events, in lieu of procuring insurance coverage, a commitment to fund a share of the bonds issued by a government entity for construction of public utilities in the event that other industrial users of the facility default on their utility payments and leases of assets containing general lease indemnities and guaranteed residual values. General guarantees associated with dispositions —Over the years, we have sold various assets in the normal course of our business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based. Contractual Commitments and Contingencies At March 31, 2020 , our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $626 million .

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Subsequent to the end of the quarter, we completed a number of financing activities to enhance our liquidity as described below. 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 $5.0 billion five-year revolving credit facility and $1.0 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 amounts outstanding under its five-year revolving credit facility. The following table shows our available credit capacity, excluding MPLX, as of May 5, 2020. (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Expiration 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) 5,000 750 1 4,249 October 2023 MPC trade receivables securitization facility (b) 517 — — 517 July 2021 Available capacity, excluding MPLX, as of May 5, 2020 6,766 (a) Borrowed $2 billion on March 30, 2020 and $1.5 billion in April. Repaid $2.75 billion in May. (b) 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. As of April 30, 2020 eligible trade receivables supported borrowings of approximately $517 million

Description of the Business a_2

Description of the Business and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 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)	3 Months Ended
	Mar. 31, 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: Three Months Ended (In millions) 2020 2019 Increase due to the issuance of MPLX & ANDX common units $ 2 $ 4 Tax impact (7 ) (1 ) Increase (decrease) in MPC's additional paid-in capital, net of tax $ (5 ) $ 3

Impairments (Tables)

Impairments (Tables)	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Details of Impairments	The table below provides information related to the impairments recognized during the first quarter of 2020 and the location of these impairments within the consolidated statements of income. (In millions) Income Statement Line Impairment Goodwill Impairment expense $ 7,330 Equity method investments Income (loss) from equity method investments 1,315 Long-lived assets Impairment expense 492 Total impairments $ 9,137
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 March 31, 2020 $ — $ 4,951 $ 7,759 $ 12,710

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2020
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [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) March 31, December 31, Assets Cash and cash equivalents $ 57 $ 15 Receivables, less allowance for doubtful accounts 544 615 Inventories 105 110 Other current assets 45 110 Equity method investments 3,992 5,275 Property, plant and equipment, net 22,030 22,174 Goodwill 7,722 9,536 Right of use assets 352 365 Other noncurrent assets 1,105 1,323 Liabilities Accounts payable $ 521 $ 744 Payroll and benefits payable 1 5 Accrued taxes 72 80 Debt due within one year 4 9 Operating lease liabilities 67 66 Other current liabilities 268 259 Long-term debt 20,467 19,704 Deferred income taxes 11 12 Long-term operating lease liabilities 284 302 Deferred credits and other liabilities 422 409

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Sales to Related Parties	Transactions with related parties were as follows: Three Months Ended (In millions) 2020 2019 Sales to related parties $ 165 $ 186 Purchases from related parties 195 204 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.

Loss per Share (Tables)

Loss per Share (Tables)	3 Months Ended
	Mar. 31, 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 (In millions, except per share data) 2020 2019 Basic loss per share: Allocation of loss: Net loss attributable to MPC $ (9,234 ) $ (7 ) Income allocated to participating securities — — Loss available to common stockholders – basic $ (9,234 ) $ (7 ) Weighted average common shares outstanding 648 673 Basic loss per share $ (14.25 ) $ (0.01 ) Diluted loss per share: Allocation of loss: Net loss attributable to MPC $ (9,234 ) $ (7 ) Income allocated to participating securities — — Loss available to common stockholders – diluted $ (9,234 ) $ (7 ) Weighted average common shares outstanding 648 673 Effect of dilutive securities — — Weighted average common shares, including dilutive effect 648 673 Diluted loss per share $ (14.25 ) $ (0.01 )
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 (In millions) 2020 2019 Shares issuable under stock-based compensation plans 10 7

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Share Repurchases	Total share repurchases were as follows for the respective periods: Three Months Ended (In millions, except per share data) 2020 2019 Number of shares repurchased — 14 Cash paid for shares repurchased $ — $ 885 Average cost per share $ — $ 62.98

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2020 Revenues: Third party (a) $ 17,528 $ 6,769 $ 918 $ 25,215 Intersegment 3,617 2 1,242 4,861 Segment revenues $ 21,145 $ 6,771 $ 2,160 $ 30,076 Segment income (loss) from operations $ (622 ) $ 519 $ 905 $ 802 Supplemental Data Depreciation and amortization (b) $ 447 $ 125 $ 345 $ 917 Capital expenditures and investments (c) 459 76 474 1,009 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended March 31, 2019 Revenues: Third party (a) $ 19,920 $ 7,376 $ 957 $ 28,253 Intersegment 4,416 2 1,232 5,650 Segment revenues $ 24,336 $ 7,378 $ 2,189 $ 33,903 Segment income (loss) from operations $ (334 ) $ 170 $ 908 $ 744 Supplemental Data Depreciation and amortization (b) $ 427 $ 126 $ 307 $ 860 Capital expenditures and investments (c) 394 73 823 1,290 (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 unallocated items and are included in items not allocated to segments in the reconciliation below. (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 (In millions) 2020 2019 Segment income from operations $ 802 $ 744 Items not allocated to segments: Corporate and other unallocated items (a) (227 ) (191 ) Equity method investment restructuring gain (b) — 207 Transaction-related costs (c) (35 ) (91 ) Impairments (d) (9,137 ) — Inventory market valuation adjustment (e) (3,220 ) — Income (loss) from operations (11,817 ) 669 Net interest and other financial costs 338 306 Income (loss) before income taxes $ (12,155 ) $ 363 (a) Corporate and other unallocated items consist primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Retail segments. (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 (In millions) 2020 2019 Segment capital expenditures and investments $ 1,009 $ 1,290 Less investments in equity method investees 169 325 Plus items not allocated to segments: Corporate 27 10 Capitalized interest 29 31 Total capital expenditures (a) $ 896 $ 1,006 (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 three months ended March 31, 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)	3 Months Ended
	Mar. 31, 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 (In millions) 2020 2019 Interest income $ (6 ) $ (9 ) Interest expense 357 340 Interest capitalized (36 ) (32 ) Pension and other postretirement non-service credits (a) (3 ) (3 ) Other financial costs 26 10 Net interest and other financial costs $ 338 $ 306 (a) See Note 21 .

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the federal statutory income tax rate applied to income (loss) before income taxes to the (benefit) provision for income taxes follows: Three Months Ended 2020 2019 Statutory rate applied to income before income taxes 21 % 21 % State and local income taxes, net of federal income tax effects 2 12 Goodwill impairment (10 ) — Noncontrolling interests (1 ) (4 ) CARES Act legislation 3 — Other 1 — Effective tax rate 16 % 29 %

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2020
Inventory Disclosure [Abstract]
Summary Of Inventories	(In millions) March 31, December 31, Crude oil $ 3,717 $ 3,472 Refined products 5,700 5,548 Materials and supplies 1,000 996 Merchandise 248 227 Inventories before LCM inventory valuation reserve 10,665 10,243 LCM inventory valuation reserve (3,220 ) — Total $ 7,445 $ 10,243

Equity Method Investments (Tabl

Equity Method Investments (Tables)	3 Months Ended
	Mar. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Summarized Financial Information For Equity Method Investees	Summarized financial information, in the aggregate, for our significant equity method investments on a 100 percent basis were as follows: Three Months Ended (In millions) 2020 2019 Revenues and other income $ 1,072 $ 1,628 Income (loss) from operations (20 ) 336 Net income (loss) (44 ) 314

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Summary Of Property, Plant And Equipment	(In millions) March 31, December 31, Refining & Marketing $ 29,511 $ 29,037 Retail 7,161 7,104 Midstream 27,490 27,193 Corporate and Other 1,308 1,289 Total 65,470 64,623 Less accumulated depreciation (a) 20,137 19,008 Property, plant and equipment, net $ 45,333 $ 45,615 (a) The March 31, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020. See Note 4 for additional information.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Assets and Liabilities Accounted for at Fair Value on Recurring Basis	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of March 31, 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. March 31, 2020 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Assets: Commodity contracts $ 754 $ 32 $ — $ (679 ) $ 107 $ 7 Liabilities: Commodity contracts $ 610 $ 19 $ — $ (628 ) $ 1 $ — Embedded derivatives in commodity contracts — — 45 — 45 — 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 March 31, 2020 , cash collateral of $67 million was netted with mark-to-market assets and $16 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 (In millions) 2020 2019 Beginning balance $ 60 $ 61 Unrealized and realized (gains) losses included in net income (14 ) 6 Settlements of derivative instruments (1 ) (2 ) Ending balance $ 45 $ 65 The amount of total (gains) losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: $ (13 ) $ 5

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 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) March 31, 2020 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 786 $ 629 Other current liabilities (a) — 2 Deferred credits and other liabilities (a) — 43 (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 March 31, 2020 . Percentage of contracts that expire next quarter Position (Units in thousands of barrels) Long Short Exchange-traded (a) Crude oil 94.8% 29,202 46,121 Refined products 84.3% 20,370 16,960 Blending products 100.0% 3,581 3,359 (a) Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 3,840 long and 640 short; Refined products - 2,575 long and 1,775 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 Income Statement Location 2020 2019 Sales and other operating revenues $ 84 $ (20 ) Cost of revenues 131 (80 ) Total $ 215 $ (100 )

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Outstanding Borrowings	Our outstanding borrowings at March 31, 2020 and December 31, 2019 consisted of the following: (In millions) March 31, December 31, Marathon Petroleum Corporation: Bank revolving credit facility $ 2,000 $ — Senior notes 8,474 8,474 Notes payable 10 10 Finance lease obligations 692 679 MPLX LP: Bank revolving credit facility 750 — Term loan facility 1,000 1,000 Senior notes 19,100 19,100 Finance lease obligations 14 19 Total debt $ 32,040 $ 29,282 Unamortized debt issuance costs (129 ) (134 ) Unamortized (discount) premium, net (302 ) (310 ) Amounts due within one year (1,710 ) (711 ) Total long-term debt due after one year $ 29,899 $ 28,127
Schedule of Line of Credit Facilities [Table Text Block]	Available Capacity under our Facilities as of March 31, 2020 (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Weighted Average Interest Rate Expiration MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2020 MPC bank revolving credit facility (a) 5,000 2,000 1 2,999 1.89 % October 2023 MPC trade receivables securitization facility (b) 750 — — 750 — July 2021 MPLX bank revolving credit facility (c) 3,500 750 — 2,750 1.94 % July 2024 (a) Borrowed $2 billion on March 30, 2020. (b) Borrowed $925 million and repaid $925 million during the three months ended March 31, 2020 . (c) Borrowed $1.325 billion at an average interest rate of 2.14 percent and repaid $575 million during the three months ended March 31, 2020 .

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2020 Refined products $ 16,539 $ 5,289 $ 169 $ 21,997 Merchandise 1 1,456 — 1,457 Crude oil 875 — — 875 Midstream services and other 113 24 749 886 Sales and other operating revenues $ 17,528 $ 6,769 $ 918 $ 25,215 (In millions) Refining & Marketing Retail Midstream Total Three Months Ended March 31, 2019 Refined products $ 18,750 $ 5,947 $ 216 $ 24,913 Merchandise 1 1,409 — 1,410 Crude oil 1,071 — — 1,071 Midstream services and other 98 20 741 859 Sales and other operating revenues $ 19,920 $ 7,376 $ 957 $ 28,253

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information	Three Months Ended (In millions) 2020 2019 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 303 $ 269 Net income taxes paid to taxing authorities (9 ) 42 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) March 31, December 31, Cash and cash equivalents $ 1,690 $ 1,527 Restricted cash (a) 4 2 Cash, cash equivalents and restricted cash $ 1,694 $ 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: Three Months Ended (In millions) 2020 2019 Additions to property, plant and equipment per the consolidated statements of cash flows $ 1,062 $ 1,241 Decrease in capital accruals (166 ) (235 ) Total capital expenditures $ 896 $ 1,006

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Changes in Accumulated Other Comprehensive Loss by Component	The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2018 $ (132 ) $ (23 ) $ 2 $ 9 $ (144 ) Other comprehensive loss before reclassifications, net of tax of $0 (1 ) — — — (1 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (11 ) — — — (11 ) – actuarial loss (a) 4 — — — 4 – settlement loss (a) — — — — — Other — — — (1 ) (1 ) Tax effect 2 — — — 2 Other comprehensive loss (6 ) — — (1 ) (7 ) Balance as of March 31, 2019 $ (138 ) $ (23 ) $ 2 $ 8 $ (151 ) (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 ($1) (2 ) (2 ) — — (4 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (11 ) — — — (11 ) – actuarial loss (a) 8 1 — — 9 – settlement loss (a) — — — — — Other — — — (1 ) (1 ) Tax effect 1 — — — 1 Other comprehensive loss (4 ) (1 ) — (1 ) (6 ) Balance as of March 31, 2020 $ (216 ) $ (117 ) $ 1 $ 6 $ (326 ) (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)	3 Months Ended
	Mar. 31, 2020
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Costs	The following summarizes the components of net periodic benefit costs: Three Months Ended March 31, Pension Benefits Other Benefits (In millions) 2020 2019 2020 2019 Components of net periodic benefit cost: Service cost $ 69 $ 58 $ 9 $ 8 Interest cost 25 28 8 9 Expected return on plan assets (34 ) (32 ) — — Amortization – prior service credit (11 ) (11 ) — — – actuarial loss 8 4 1 — – settlement loss — — — — Net periodic benefit cost $ 57 $ 47 $ 18 $ 17

Subsequent Events (Tables)

Subsequent Events (Tables)	May 05, 2020	Mar. 31, 2020
Subsequent Event [Line Items]
Schedule of Line of Credit Facilities [Table Text Block]		Available Capacity under our Facilities as of March 31, 2020 (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Weighted Average Interest Rate Expiration MPC 364-day bank revolving credit facility $ 1,000 $ — $ — $ 1,000 — September 2020 MPC bank revolving credit facility (a) 5,000 2,000 1 2,999 1.89 % October 2023 MPC trade receivables securitization facility (b) 750 — — 750 — July 2021 MPLX bank revolving credit facility (c) 3,500 750 — 2,750 1.94 % July 2024 (a) Borrowed $2 billion on March 30, 2020. (b) Borrowed $925 million and repaid $925 million during the three months ended March 31, 2020 . (c) Borrowed $1.325 billion at an average interest rate of 2.14 percent and repaid $575 million during the three months ended March 31, 2020 .
Subsequent Event
Subsequent Event [Line Items]
Schedule of Line of Credit Facilities [Table Text Block]	The following table shows our available credit capacity, excluding MPLX, as of May 5, 2020. (Dollars in millions) Total Capacity Outstanding Borrowings Outstanding Letters of Credit Available Capacity Expiration 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) 5,000 750 1 4,249 October 2023 MPC trade receivables securitization facility (b) 517 — — 517 July 2021 Available capacity, excluding MPLX, as of May 5, 2020 6,766 (a) Borrowed $2 billion on March 30, 2020 and $1.5 billion in April. Repaid $2.75 billion in May. (b) 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. As of April 30, 2020 eligible trade receivables supported borrowings of approximately $517 million

Description of the Business a_3

Description of the Business and Basis of Presentation (Details) bbl / d in Millions	3 Months Ended
	Mar. 31, 2020Storebbl / drefinery
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Capacity | bbl / d	3
Number of refineries | refinery	16
Number of branded outlets	6,900
Number of retail transportation fuel and convenience stores	3,880
Number of direct dealer locations	1,070

Accounting Standards (Details)

Accounting Standards (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Receivables, less allowance for doubtful accounts	$ 5,583	$ 7,479
Allowance for doubtful accounts	$ 18	$ 17

Master Limited Partnership (Det

Master Limited Partnership (Details)	Mar. 31, 2020
MPLX | Marathon Petroleum Corporation [Member]
MPC's partnership interest in MLP (in percentage)	63.00%

Master Limited Partnership - MP

Master Limited Partnership - MPLX's Acquisition of MPLX (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 30, 2019	Mar. 31, 2020	Mar. 31, 2019
Equity transactions of MPLX & ANDX		$ (7)	$ 2
Public
Common units conversion ratio	1.135
Nonpublic
Common units conversion ratio	1.0328
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)	(5)	3
Deferred income tax impact from changes in equity	$ (642)	$ (7)	$ (1)

Master Limited Partnership - No

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

Impairments - Income Statement

Impairments - Income Statement Location of Impairments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 7,330
Total impairments	9,137	[1]
Impairment expense
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	7,330
Long-lived assets impairment	492
Income (loss) from equity method investments
Finite-Lived Intangible Assets [Line Items]
Equity method investment impairment	$ 1,315
[1]	Includes goodwill impairment, impairment of equity method investments and impairment of long lived assets. See Note 4

Impairments - Goodwill (Details

Impairments - Goodwill (Details) - Discounted Cash Flow - Discount Rate	12 Months Ended
	Dec. 31, 2019
Minimum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs	9.00%
Maximum
Finite-Lived Intangible Assets [Line Items]
Fair value inputs	13.50%

Impairments - Schedule of Goodw

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

Impairments - Equity Method Inv

Impairments - Equity Method Investments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
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) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
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	21.00%

Variable Interest Entities - Co

Variable Interest Entities - Consolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets
Cash and cash equivalents	$ 1,690	$ 1,527
Receivables, less allowance for doubtful accounts	5,583	7,479
Inventories	7,445	10,243
Other current assets	975	921
Equity method investments	5,656	6,898
Property, plant and equipment, net	45,333	45,615
Goodwill	12,710	20,040
Right of use assets	2,562	2,459
Other noncurrent assets	4,363	3,374
Liabilities
Accounts payable	8,106	11,623
Payroll and benefits payable	1,107	1,126
Accrued taxes	1,098	1,186
Debt due within one year	1,710	711
Operating lease liabilities	630	604
Other current liabilities	918	897
Long-term debt	29,899	28,127
Deferred income taxes	5,772	6,392
Long-term operating lease liabilities	1,949	1,875
Deferred credits and other liabilities	1,229	1,265
Variable Interest Entity, Primary Beneficiary [Member] | MPLX
Assets
Cash and cash equivalents	57	15
Receivables, less allowance for doubtful accounts	544	615
Inventories	105	110
Other current assets	45	110
Equity method investments	3,992	5,275
Property, plant and equipment, net	22,030	22,174
Goodwill	7,722	9,536
Right of use assets	352	365
Other noncurrent assets	1,105	1,323
Liabilities
Accounts payable	521	744
Payroll and benefits payable	1	5
Accrued taxes	72	80
Debt due within one year	4	9
Operating lease liabilities	67	66
Other current liabilities	268	259
Long-term debt	20,467	19,704
Deferred income taxes	11	12
Long-term operating lease liabilities	284	302
Deferred credits and other liabilities	$ 422	$ 409

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Related Party Transactions [Abstract]
Sales to related parties	$ 165	$ 186
Purchases from related parties	$ 195	$ 204

Loss Per Share - Summary of Los

Loss Per Share - Summary of Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic loss per share:
Net loss attributable to MPC	$ (9,234)	$ (7)
Income allocated to participating securities	0	0
Loss available to common stockholders – basic	$ (9,234)	$ (7)
Weighted average common shares outstanding (in shares)	648	673
Basic loss per share	$ (14.25)	$ (0.01)
Diluted loss per share:
Net loss attributable to MPC	$ (9,234)	$ (7)
Income allocated to participating securities	0	0
Loss available to common stockholders – diluted	$ (9,234)	$ (7)
Weighted average common shares outstanding (in shares)	648	673
Effect of dilutive securities (in shares)	0	0
Weighted average common shares, including dilutive effect (in shares)	648	673
Diluted loss per share	$ (14.25)	$ (0.01)

Loss Per Share - Anti-dilutive

Loss Per Share - Anti-dilutive Shares (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stock Based Compensation Expense [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issuable under stock-based compensation plans	10	7

Equity - Additional Information

Equity - Additional Information (Detail) $ in Millions	Mar. 31, 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
	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Number of shares repurchased	0	14
Cash paid for shares repurchased	$ 0	$ 885
Average cost per share	$ 0	$ 62.98

Segment Information - Additiona

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020Segmentrefinery
Segment Reporting [Abstract]
Number of reportable segments | Segment	3
Number of refineries | refinery	16

Segment Information - Income Fr

Segment Information - Income From Operations Attributable To Operating Segments (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Sales and other operating revenues		$ 25,215	$ 28,253
Income from operations		(11,817)	669
Depreciation and amortization		962	919
Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		4,861	5,650
Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		30,076	33,903
Income from operations		802	744
Depreciation and amortization	[1]	917	860
Capital expenditures and investments	[2]	1,009	1,290
Refining & Marketing
Segment Reporting Information [Line Items]
Sales and other operating revenues		17,528	19,920
Refining & Marketing | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		3,617	4,416
Refining & Marketing | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		21,145	24,336
Income from operations		(622)	(334)
Depreciation and amortization		447	427
Capital expenditures and investments		459	394
Retail
Segment Reporting Information [Line Items]
Sales and other operating revenues		6,769	7,376
Retail | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		2	2
Retail | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		6,771	7,378
Income from operations		519	170
Depreciation and amortization		125	126
Capital expenditures and investments		76	73
Midstream
Segment Reporting Information [Line Items]
Sales and other operating revenues		918	957
Midstream | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues		1,242	1,232
Midstream | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues		2,160	2,189
Income from operations		905	908
Depreciation and amortization		345	307
Capital expenditures and investments		474	823
Reportable Segment
Segment Reporting Information [Line Items]
Sales and other operating revenues	[3]	$ 25,215	$ 28,253
[1]	Differences between segment totals and MPC consolidated totals represent amounts related to corporate and other unallocated items and are included in items not allocated to segments in the reconciliation below.
[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 - Reconcili

Segment Information - Reconciliation Of Segment Income From Operations To Income Before Income Taxes (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		$ (11,817)		$ 669
Impairments	[1]	9,137
Inventory market valuation adjustment		3,220		0
Net interest and other financial costs		338		306
Income before income taxes		(12,155)		363
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		802		744
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations	[2]	(227)		(191)
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Equity method investment restructuring gain		0		207	[3]
Transaction-related costs	[4]	(35)		(91)
Impairments		(9,137)	[1]	0
Inventory market valuation adjustment		$ (3,220)	[5]	$ 0
[1]	Includes goodwill impairment, impairment of equity method investments and impairment of long lived assets. See Note 4
[2]	Corporate and other unallocated items consist primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets, except for corporate overhead expenses attributable to MPLX, which are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Retail segments.
[3]	Includes gain related to Capline Pipeline Company LLC (“Capline LLC”). See Note 13 .
[4]	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.
[5]	See Note 12 .

Segment Information - Reconci_2

Segment Information - Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Plus items not allocated to segments:
Capital expenditures	[1]	$ 896	$ 1,006
Operating Segments
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments	[2]	1,009	1,290
Less investments in equity method investees		169	325
Corporate and Other
Plus items not allocated to segments:
Corporate		27	10
Capitalized interest		$ 29	$ 31
[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 three months ended March 31, 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
		Mar. 31, 2020	Mar. 31, 2019
Other Income and Expenses [Abstract]
Interest income		$ (6)	$ (9)
Interest expense		357	340
Interest capitalized		(36)	(32)
Pension and other postretirement non-service credits	[1]	(3)	(3)
Other financial costs		26	10
Net interest and other financial costs		$ 338	$ 306
[1]	See Note 21 .

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CARES Act, income tax expense (benefit)	$ (411)
Effective income tax rate, percent	16.00%	29.00%
Unrecognized benefits	$ 27
Other noncurrent assets
Income tax receivable, noncurrent	$ 1,300

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Tax Rate (Details)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Statutory rate applied to income before income taxes	21.00%	21.00%
State and local income taxes, net of federal income tax effects	2.00%	12.00%
Goodwill impairment	(10.00%)	0.00%
Noncontrolling interests	(1.00%)	(4.00%)
CARES Act legislation	3.00%	0.00%
Other	1.00%	0.00%
Effective tax rate	16.00%	29.00%

Income Taxes - Out of Period Ad

Income Taxes - Out of Period Adjustment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Provision (benefit) for income taxes	$ (1,937)	$ 104
Andeavor | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Provision (benefit) for income taxes	$ 36

Inventories - Summary Of Invent

Inventories - Summary Of Inventories (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Crude oil	$ 3,717	$ 3,472
Refined products	5,700	5,548
Materials and supplies	1,000	996
Merchandise	248	227
Inventories before LCM inventory valuation reserve	10,665	10,243
LCM inventory valuation reserve	(3,220)	0
Total	$ 7,445	$ 10,243

Inventories - Additional Inform

Inventories - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Inventory Disclosure [Abstract]
Impact on income as a result of LIFO liquidations	$ 0

Equity Method Investments - Sig

Equity Method Investments - Significant Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Revenues and other income	$ 1,072	$ 1,628
Income (loss) from operations	(20)	336
Net income (loss)	$ (44)	$ 314

Equity Method Investments - Cap

Equity Method Investments - Capline LLC (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Contribution of net assets	$ 0	$ 143	[1]
Fair value of assets acquired	$ 0	$ 350	[2]
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 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

Property, Plant And Equipment -

Property, Plant And Equipment - Summary Of Property, Plant And Equipment (Detail) - USD ($) $ in Millions	Mar. 31, 2020		Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 65,470		$ 64,623
Less accumulated depreciation(a)	20,137	[1]	19,008
Property, plant and equipment, net	45,333		45,615
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	29,511		29,037
Operating Segments | Retail
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,161		7,104
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	27,490		27,193
Corporate and Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,308		$ 1,289
[1]	The March 31, 2020 balance includes property, plant and equipment impairment charges recorded during the first quarter of 2020. See Note 4 for additional information.

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash collateral netted with derivatives assets		$ 67
Cash collateral netted with derivative liabilities		16	$ 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]	(679)	(55)
Commodity derivative instruments, assets - net carrying value on balance sheet	[2]	107	8
Commodity derivative instruments, assets - collateral pledged not offset		7	73
Commodity derivative instruments, liabilities - netting and collateral	[1]	(628)	(106)
Commodity derivative instruments, liabilities - net carrying value on balance sheet	[2]	1	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]	45	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		754	57
Commodity derivative instruments, liabilities - gross		610	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		32	6
Commodity derivative instruments, liabilities - gross		19	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		$ 45	$ 60
[1]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of March 31, 2020 , cash collateral of $67 million was netted with mark-to-market assets and $16 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 - Recur

Fair Value Measurements - Recurring Narrative (Detail)	3 Months Ended
	Mar. 31, 2020USD ($)$ / gal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Average forward price | $ / gal	0.39
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	$ 0.26
Level 3 | Commodity derivatives | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	$ 0.68
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	95.00%
Probability of renewal second term	83.50%

Fair Value Measurements - Recon

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
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 60	$ 61
Unrealized and realized (gains) losses included in net income	(14)	6
Settlements of derivative instruments	(1)	(2)
Ending balance	$ 45	$ 65

Fair Value Measurements - Losse

Fair Value Measurements - Losses Included in Earnings Relating to Assets Still Held at End of Period (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
The amount of total (gains) losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period:	$ (13)	$ 5

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values - Reported (Detail) - USD ($) $ in Billions	Mar. 31, 2020	Dec. 31, 2019
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 27.7	$ 30.1
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 31	$ 28.3

Derivatives - Classification of

Derivatives - Classification of Gross Fair Values of Derivative Instruments, Excluding Cash Collateral (Detail) - Commodity derivatives - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Other current assets
Derivatives, Fair Value [Line Items]
Asset		$ 786	$ 63
Liability		629	106
Other current liabilities(a)
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	2	5
Deferred credits and other liabilities
Derivatives, Fair Value [Line Items]
Asset		0	0
Liability	[1]	$ 43	$ 55
[1]	Includes embedded derivatives.

Derivatives - Open Commodity De

Derivatives - Open Commodity Derivative Contracts (Details) - Exchange Traded gal in Thousands, bbl in Thousands	3 Months Ended
	Mar. 31, 2020bblgal
Crude oil
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	94.80%
Crude oil | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	29,202	[1]
Crude oil | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	3,840
Crude oil | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	46,121	[1]
Crude oil | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	640
Refined products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	84.30%
Refined products | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	20,370	[1]
Refined products | Long | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	2,575
Refined products | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	16,960	[1]
Refined products | Short | Spread Contracts
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	1,775
Blending products
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	100.00%
Blending products | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	3,581	[1]
Blending products | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels) | gal	3,359	[1]
[1]	Included in exchange-traded are spread contracts in thousands of barrels: Crude oil - 3,840 long and 640 short; Refined products - 2,575 long and 1,775 short

Derivatives - Effect of Commodi

Derivatives - Effect of Commodity Derivative Instruments in Statements of Income (Detail) - Commodity derivatives - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ 215	$ (100)
Sales and other operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	84	(20)
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ 131	$ (80)

Debt - Outstanding Borrowings (

Debt - Outstanding Borrowings (Detail) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Total debt		$ 32,040	$ 29,282
Unamortized debt issuance costs		(129)	(134)
Unamortized (discount) premium, net		(302)	(310)
Amounts due within one year		(1,710)	(711)
Total long-term debt due after one year		29,899	28,127
MPLX bank revolving credit facility
Long-term line of credit	[1]	750
Marathon Petroleum Corporation:
Notes payable		10	10
Marathon Petroleum Corporation: | Bank revolving credit facility
Long-term line of credit		2,000	0
Marathon Petroleum Corporation: | Senior notes
Long-term debt, gross		8,474	8,474
Marathon Petroleum Corporation: | Finance Lease
Finance lease liabilities		692	679
MPLX LP: | MPLX bank revolving credit facility
Long-term line of credit		750	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		$ 14	$ 19
[1]	Borrowed $1.325 billion at an average interest rate of 2.14 percent and repaid $575 million during the three months ended March 31, 2020

Debt - Available Capacity under

Debt - Available Capacity under our Facilities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
MPC 364-day bank revolving credit facility
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	2,000	[1]
Outstanding Letters of Credit	1
Available Capacity	$ 2,999
Weighted Average Interest Rate	1.89%
Borrowings	$ 2,000
MPC trade receivables securitization facility
Debt Instrument [Line Items]
Total Capacity	750
Outstanding Borrowings	0	[2],[3]
Outstanding Letters of Credit	0
Available Capacity	$ 750
Weighted Average Interest Rate	0.00%
Borrowings	$ 925
Repayments	925
MPLX bank revolving credit facility
Debt Instrument [Line Items]
Total Capacity	3,500
Outstanding Borrowings	750	[4]
Outstanding Letters of Credit	0
Available Capacity	$ 2,750
Weighted Average Interest Rate	1.94%
Borrowings	$ 1,325
Repayments	$ 575
Weighted average interest rate over time	2.14%
[1]	Borrowed $2 billion on March 30, 2020.
[2]	Borrowed $925 million and repaid $925 million during the three months ended March 31, 2020 .
[3]	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. As of April 30, 2020 eligible trade receivables supported borrowings of approximately $517 million
[4]	Borrowed $1.325 billion at an average interest rate of 2.14 percent and repaid $575 million during the three months ended March 31, 2020

Revenue - Disaggregated by Prod

Revenue - Disaggregated by Product Line (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Sales and other operating revenues	$ 25,215	$ 28,253
Refined products
Sales and other operating revenues	21,997	24,913
Merchandise
Sales and other operating revenues	1,457	1,410
Crude oil
Sales and other operating revenues	875	1,071
Midstream services and other
Sales and other operating revenues	886	859
Refining & Marketing
Sales and other operating revenues	17,528	19,920
Refining & Marketing | Refined products
Sales and other operating revenues	16,539	18,750
Refining & Marketing | Merchandise
Sales and other operating revenues	1	1
Refining & Marketing | Crude oil
Sales and other operating revenues	875	1,071
Refining & Marketing | Midstream services and other
Sales and other operating revenues	113	98
Retail
Sales and other operating revenues	6,769	7,376
Retail | Refined products
Sales and other operating revenues	5,289	5,947
Retail | Merchandise
Sales and other operating revenues	1,456	1,409
Retail | Crude oil
Sales and other operating revenues	0	0
Retail | Midstream services and other
Sales and other operating revenues	24	20
Midstream
Sales and other operating revenues	918	957
Midstream | Refined products
Sales and other operating revenues	169	216
Midstream | Merchandise
Sales and other operating revenues	0	0
Midstream | Crude oil
Sales and other operating revenues	0	0
Midstream | Midstream services and other
Sales and other operating revenues	$ 749	$ 741

Revenue (Details)

Revenue (Details) $ in Millions	Mar. 31, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Matching buy/sell receivables	$ 2,330

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 303	$ 269
Net income taxes paid to taxing authorities	(9)	42
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 Equalivalents and Restricted Cash (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents		$ 1,690	$ 1,527
Restricted cash	[1]	4	2
Cash, cash equivalents and restricted cash		$ 1,694	$ 1,529	$ 908	$ 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
		Mar. 31, 2020	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Additions to property, plant and equipment per the consolidated statements of cash flows		$ 1,062	$ 1,241
Decrease in capital accruals		(166)	(235)
Capital expenditures	[1]	$ 896	$ 1,006
[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 three months ended March 31, 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
		Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (320)	$ (144)
Other comprehensive income (loss), before reclassifications, net of tax		(4)	(1)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit		(11)	(11)
Amortization - actuarial loss		9	4
Amortization - settlement loss		0	0
Other		(1)	(1)
Tax effect		1	2
Other comprehensive loss		(6)	(7)
Ending balance		(326)	(151)
Other comprehensive income (loss) before reclassifications, tax		1	0
Accumulated Defined Benefit Plans Adjustment | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(212)	(132)
Other comprehensive income (loss), before reclassifications, net of tax		(2)	(1)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]	(11)	(11)
Amortization - actuarial loss	[1]	8	4
Amortization - settlement loss	[1]	0	0
Tax effect		1	2
Other comprehensive loss		(4)	(6)
Ending balance		(216)	(138)
Accumulated Defined Benefit Plans Adjustment | Other Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(116)	(23)
Other comprehensive income (loss), before reclassifications, net of tax		(2)	0
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]	0	0
Amortization - actuarial loss	[1]	1	0
Amortization - settlement loss		0	0
Tax effect		0	0
Other comprehensive loss		(1)	0
Ending balance		(117)	(23)
Gain on Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		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 loss		0	0
Ending balance		1	2
Workers Compensation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		7	9
Other comprehensive income (loss), before reclassifications, net of tax		0	0
Amounts reclassified from accumulated other comprehensive loss:
Other		(1)	(1)
Tax effect		0	0
Other comprehensive loss		(1)	(1)
Ending balance		$ 6	$ 8
[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
	Mar. 31, 2020	Mar. 31, 2019
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 69	$ 58
Interest cost	25	28
Expected return on plan assets	(34)	(32)
Amortization – prior service credit	(11)	(11)
Amortization – actuarial loss	8	4
Amortization - settlement loss	0	0
Net periodic benefit cost	57	47
Other Benefits
Components of net periodic benefit cost:
Service cost	9	8
Interest cost	8	9
Expected return on plan assets	0	0
Amortization – prior service credit	0	0
Amortization – actuarial loss	1	0
Amortization - settlement loss	0	0
Net periodic benefit cost	$ 18	$ 17

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 3
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	6
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	$ 11

Commitments and Contingencies (

Commitments and Contingencies (Detail)	3 Months Ended
	Mar. 31, 2020
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, inestimable loss	For matters for which we have not recorded a liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings.

Commitments and Contingencies -

Commitments and Contingencies - Environmental Matters (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Accrued liabilities for remediation	$ 418	$ 433
Receivables for recoverable costs	$ 29	$ 29

Commitments and Contingencies_2

Commitments and Contingencies - Guarantees (Details) $ in Millions	Mar. 31, 2020USD ($)
Other Guarantees
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 103
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 | 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
Indirect Ownership Interest | Bakken Pipeline System
Loss Contingencies [Line Items]
Ownership percentage	9.19%

Commitments and Contingencies_3

Commitments and Contingencies - Contractual Commitments and Contingencies (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	$ 626

Subsequent Events - Additional

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

Subsequent Events - MPC Senior

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

Subsequent Events - Available c

Subsequent Events - Available capacity, excluding MPLX (Details) - USD ($) $ in Millions		May 05, 2020	Apr. 30, 2020	Mar. 31, 2020
MPC 364-day bank revolving credit facility due September 2020
Subsequent Event [Line Items]
Total Capacity				$ 1,000
Outstanding Borrowings				0
Outstanding Letters of Credit				0
Available Capacity				1,000
MPC bank revolving credit facility
Subsequent Event [Line Items]
Total Capacity				5,000
Outstanding Borrowings	[1]			2,000
Outstanding Letters of Credit				1
Available Capacity				2,999
Borrowings				2,000
MPC trade receivables securitization facility
Subsequent Event [Line Items]
Total Capacity				750
Outstanding Borrowings	[2],[3]			0
Outstanding Letters of Credit				0
Available Capacity				750
Borrowings				925
Repayments				$ 925
Subsequent Event
Subsequent Event [Line Items]
Available Capacity		$ 6,766
Subsequent Event | MPC 364-day bank revolving credit facility due September 2020
Subsequent Event [Line Items]
Total Capacity		1,000
Outstanding Borrowings		0
Outstanding Letters of Credit		0
Available Capacity		1,000
Subsequent Event | MPC 364-day bank revolving credit facility
Subsequent Event [Line Items]
Total Capacity		1,000
Outstanding Borrowings		0
Outstanding Letters of Credit		0
Available Capacity		1,000
Subsequent Event | MPC bank revolving credit facility
Subsequent Event [Line Items]
Total Capacity		5,000
Outstanding Borrowings	[4]	750
Outstanding Letters of Credit		1
Available Capacity		4,249
Borrowings			$ 1,500
Repayments		2,750
Subsequent Event | MPC trade receivables securitization facility
Subsequent Event [Line Items]
Total Capacity		517
Outstanding Borrowings		0
Outstanding Letters of Credit		0
Available Capacity		517
Maximum borrowing capacity		$ 750
[1]	Borrowed $2 billion on March 30, 2020.
[2]	Borrowed $925 million and repaid $925 million during the three months ended March 31, 2020 .
[3]	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. As of April 30, 2020 eligible trade receivables supported borrowings of approximately $517 million
[4]	Borrowed $2 billion on March 30, 2020 and $1.5 billion in April. Repaid $2.75 billion in May.