Marathon Petroleum (MPC) 10-Q 3 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 31, 2014
Document Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	'Q3	'
Trading Symbol	'MPC	'
Entity Registrant Name	'Marathon Petroleum Corp	'
Entity Central Index Key	'0001510295	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	280,192,743

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues and other income:	'	'	'	'
Sales and other operating revenues (including consumer excise taxes)	$25,438	$26,256	$75,567	$75,263
Income from equity method investments	29	9	121	16
Net gain on disposal of assets	2	1	14	3
Other income	12	8	57	40
Total revenues and other income	25,481	26,274	75,759	75,322
Costs and expenses:	'	'	'	'
Cost of revenues (excludes items below)	21,935	23,553	65,571	65,907
Purchases from related parties	112	103	401	254
Consumer excise taxes	1,622	1,631	4,736	4,685
Depreciation and amortization	322	299	967	888
Selling, general and administrative expenses	342	305	1,004	912
Other taxes	86	82	288	259
Total costs and expenses	24,419	25,973	72,967	72,905
Income from operations	1,062	301	2,792	2,417
Net interest and other financial income (costs)	-50	-47	-144	-140
Income before income taxes	1,012	254	2,648	2,277
Provision for income taxes	333	81	898	775
Net income	679	173	1,750	1,502
Less net income attributable to noncontrolling interests	7	5	24	16
Net income attributable to MPC	$672	$168	$1,726	$1,486
Basic:	'	'	'	'
Net income attributable to MPC per share	$2.38	$0.54	$5.99	$4.63
Weighted average shares outstanding (in shares)	282	309	288	321
Diluted:	'	'	'	'
Net income attributable to MPC per share	$2.36	$0.54	$5.95	$4.60
Weighted average shares outstanding (in shares)	284	311	290	323
Dividends paid (in USD per share)	$0.50	$0.42	$1.34	$1.12

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$679	$173	$1,750	$1,502
Defined benefit postretirement and post-employment plans:	'	'	'	'
Actuarial changes, net of tax of ($1), $34, $0 and $169	-2	57	0	282
Prior service costs, net of tax of ($5), ($5), ($14) and ($14)	-8	-8	-24	-23
Other comprehensive income (loss)	-10	49	-24	259
Comprehensive income	669	222	1,726	1,761
Less comprehensive income attributable to noncontrolling interests	7	5	24	16
Comprehensive income attributable to MPC	$662	$217	$1,702	$1,745

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Actuarial changes, tax	($1)	$34	$0	$169
Prior service costs, tax	($5)	($5)	($14)	($14)

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$1,854	$2,292
Receivables, less allowance for doubtful accounts of $10 and $9	5,271	5,559
Inventories	5,608	4,689
Other current assets	154	197
Total current assets	12,887	12,737
Equity method investments	862	463
Property, plant and equipment, net	15,999	13,921
Goodwill	1,537	938
Other noncurrent assets	420	326
Total assets	31,705	28,385
Current liabilities:	'	'
Accounts payable	8,726	8,234
Payroll and benefits payable	345	406
Consumer excise taxes payable	365	373
Accrued taxes	586	513
Long-term debt due within one year	26	23
Other current liabilities	324	275
Total current liabilities	10,372	9,824
Long-term debt	6,238	3,373
Deferred income taxes	2,165	2,304
Defined benefit postretirement plan obligations	937	771
Deferred credits and other liabilities	727	781
Total liabilities	20,439	17,053
Commitments and contingencies (see Note 22)	'	'
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 - 363 million and 362 million shares (par value $0.01 per share, 1 billion shares authorized)	4	4
Held in treasury, at cost - 82 million and 65 million shares	-5,616	-4,155
Additional paid-in capital	9,833	9,768
Retained earnings	6,856	5,507
Accumulated other comprehensive loss	-228	-204
Total MPC stockholders’ equity	10,849	10,920
Noncontrolling interests	417	412
Total equity	11,266	11,332
Total liabilities and equity	$31,705	$28,385

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$10	$9
Preferred stock:	'	'
Shares issued	0	0
Shares outstanding	0	0
Par value	$0.01	'
Shares authorized	30,000,000	'
Common stock:	'	'
Shares issued	363,000,000	362,000,000
Par value	$0.01	'
Shares authorized	1,000,000,000	'
Treasury stock	-82,000,000	-65,000,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating activities:	'	'
Net income	$1,750	$1,502
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	967	888
Pension and other postretirement benefits, net	123	3
Deferred income taxes	-126	22
Net gain on disposal of assets	-14	-3
Equity method investments, net	-39	-4
Changes in the fair value of derivative instruments	-35	-54
Changes in:	'	'
Current receivables	424	-974
Inventories	-731	-1,330
Current accounts payable and accrued liabilities	318	2,028
All other, net	85	-28
Net cash provided by operating activities	2,722	2,050
Investing activities:	'	'
Additions to property, plant and equipment	-952	-733
Acquisitions, net of cash acquired	-2,831	-1,515
Disposal of assets	19	12
Investments—acquisitions, loans and contributions	-341	-113
Investments—redemptions and repayments	3	76
All other, net	78	22
Net cash used in investing activities	-4,024	-2,251
Financing activities:	'	'
Long-term debt – borrowings	2,903	0
Long-term debt – repayments	-32	-16
Debt issuance costs	-19	-2
Issuance of common stock	21	37
Common stock repurchased	-1,449	-2,341
Dividends paid	-386	-358
Distributions to noncontrolling interests	-20	-15
Tax settlement with Marathon Oil Corporation	0	39
Contingent consideration payment	-172	0
All other, net	18	15
Net cash provided by (used in) financing activities	864	-2,641
Net decrease in cash and cash equivalents	-438	-2,842
Cash and cash equivalents at beginning of period	2,292	4,860
Cash and cash equivalents at end of period	$1,854	$2,018

Consolidated_Statements_of_Equ

Consolidated Statements of Equity (USD $)	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
In Millions, unless otherwise specified
Beginning balance at Dec. 31, 2012	$12,105	$4	($1,253)	$9,527	$3,880	($464)	$411
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'
Net income	1,502	'	'	'	1,486	'	16
Dividends declared	-359	'	'	'	-359	'	'
Distributions to noncontrolling interests	-15	'	'	'	'	'	-15
Other comprehensive loss	259	'	'	'	'	259	'
Shares repurchased	-2,341	'	-2,441	100	'	'	'
Shares returned - stock based compensation	'	'	-9	'	'	'	'
Shares issued - stock based compensation	'	'	'	37	'	'	'
Net shares issued — stock based compensation	28	'	'	'	'	'	'
Stock-based compensation	46	'	'	45	'	'	1
Tax settlement with Marathon Oil Corporation	39	'	'	39	'	'	'
Ending balance at Sep. 30, 2013	11,264	4	-3,703	9,748	5,007	-205	413
Beginning balance at Dec. 31, 2013	11,332	4	-4,155	9,768	5,507	-204	412
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'
Net income	1,750	'	'	'	1,726	'	24
Dividends declared	-386	'	'	'	-386	'	'
Distributions to noncontrolling interests	-20	'	'	'	'	'	-20
Other comprehensive loss	-24	'	'	'	'	-24	'
Shares repurchased	-1,449	'	-1,449	0	'	'	'
Shares returned - stock based compensation	'	'	-12	'	'	'	'
Shares issued - stock based compensation	'	'	'	21	'	'	'
Net shares issued — stock based compensation	9	'	'	'	'	'	'
Stock-based compensation	45	'	'	44	'	'	1
Tax settlement with Marathon Oil Corporation	39	'	'	'	'	'	'
Other	9	'	'	'	9	'	'
Ending balance at Sep. 30, 2014	$11,266	$4	($5,616)	$9,833	$6,856	($228)	$417

Consolidated_Statement_of_Equi

Consolidated Statement of Equity - Shares	Total		Common Stock	Treasury Stock
In Millions
Number of shares held in treasury (beginning balance) at Dec. 31, 2012	'		'	-28
Number of common shares issued (beginning balance) at Dec. 31, 2012	'		361	'
Number of shares issued - stock-based compensation	'		1	'
Number of shares repurchased	-31		'	-31
Number of shares held in treasury (ending balance) at Sep. 30, 2013	'		'	-59
Number of common shares issued (ending balance) at Sep. 30, 2013	'		362	'
Number of shares held in treasury (beginning balance) at Dec. 31, 2013	-65		'	-65
Number of common shares issued (beginning balance) at Dec. 31, 2013	362		362	'
Number of shares issued - stock-based compensation	'		1	'
Number of shares repurchased	-17	[1]	'	-17
Number of shares held in treasury (ending balance) at Sep. 30, 2014	-82		'	-82
Number of common shares issued (ending balance) at Sep. 30, 2014	363		363	'
[1]	The nine months ended September 30, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in 2012.

Description_of_the_Business_an

Description of the Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Description of the Business and Basis of Presentation	'
	Description of the Business and Basis of Presentation
	Description of the Business—As used in this report, the terms “MPC,” “we,” “us,” “the Company” or “our” may refer to Marathon Petroleum Corporation, one or more of its consolidated subsidiaries or all of them taken as a whole.
	Our business consists of refining and marketing, retail marketing and pipeline transportation operations conducted primarily in the Midwest, Gulf Coast, East Coast and Southeast regions of the United States, through subsidiaries, including Marathon Petroleum Company LP, Speedway LLC and MPLX LP and its subsidiaries (“MPLX”).
	See Note 9 for additional information about our operations.
	Basis of Presentation—All significant intercompany transactions and accounts have been eliminated.
	These interim consolidated financial statements are unaudited; however, in the opinion of our management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules of the Securities and Exchange Commission applicable to interim period financial statements and do not include all of the information and disclosures required by United States generally accepted accounting principles (“U.S. 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, 2013. The results of operations for the three and nine months ended September 30, 2014 are not necessarily indicative of the results to be expected for the full year.
	During the first quarter of 2014, we recorded an out-of-period adjustment for additional expenses related to the prior year's bonus programs of $29 million, included in total costs and expenses on the consolidated statements of income. The impact to our consolidated results of operations for the nine months ended September 30, 2014 and for the year ended December 31, 2013 was immaterial. We do not expect this adjustment to have a material impact to our results of operations for the year ended December 31, 2014.

Accounting_Standards

Accounting Standards	9 Months Ended
	Sep. 30, 2014
Accounting Changes and Error Corrections [Abstract]	'
Accounting Standards	'
	Accounting Standards
	Not Yet Adopted
	In August 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update requiring management to assess an entity's ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. Management will be required to assess if there is substantial doubt about an entity's ability to continue as a going concern within one year after the date that the financial statements are issued. Disclosures will be required if conditions give rise to substantial doubt and the type of disclosure will be determined based on whether management's plans will be able to alleviate the substantial doubt. The accounting standards update will be effective for the first annual period ending after December 15, 2016, and for annual periods and interim periods thereafter with early application permitted.
	In June 2014, the FASB issued an accounting standards update for the elimination of the concept of development stage entity ("DSE") from U.S. GAAP and removes the related incremental reporting. The standards update eliminates the additional financial statement requirements specific to a DSE. In addition, it amends the consolidation model by eliminating the special provisions in the variable interest entity rules for assessing the sufficiency of the equity of a DSE. The portion of the accounting standards update related to the amendment to the consolidation guidance will be effective on a retrospective basis for annual reporting periods beginning after December 15, 2015, and interim periods within those years, with early adoption permitted. The portion of the accounting standards update related to the removal of the DSE reporting requirements will be effective on a retrospective basis for annual reporting periods beginning after December 15, 2014, and interim periods within those years, with early adoption permitted. Adoption of this standards update in the first quarters of 2015 and 2016 is not expected to have an impact on our consolidated results of operations, financial position or cash flows.
	In May 2014, the FASB issued an accounting standards update for revenue recognition that is aligned with the International Accounting Standards Board's revenue recognition standard issued on the same day. The guidance in the update states that revenue is recognized when a customer obtains control of a good or service. Recognition of the revenue will involve a multiple step approach including identifying the contract, identifying the separate performance obligations, determining the transaction price, allocating the price to the performance obligations and then recognizing the revenue as the obligations are satisfied. Additional disclosures will be required to provide adequate information to understand the nature, amount, timing and uncertainty of reported revenues and revenues expected to be recognized. The accounting standards update will be effective on a retrospective or modified retrospective basis for annual reporting periods beginning after December 15, 2016, and interim periods within those years, with no early adoption permitted. At this point, a final determination has not been made as to the impact of the adoption of this standards update in the first quarter of 2017. However, we do not expect it to have a material impact on our consolidated results of operations, financial position or cash flows.
	In April 2014, the FASB issued an accounting standards update that redefines the criteria for determining discontinued operations and introduces new disclosures related to these disposals. The updated definition of a discontinued operation is the disposal of a component (or components) of an entity or the classification of a component (or components) of an entity as held for sale that represents a strategic shift for an entity and has (or will have) a major impact on an entity's operations and financial results. The standard requires disclosure of additional financial information for discontinued operations and individually material components not qualifying for discontinued operation presentation, as well as information regarding an entity's continuing involvement with the discontinued operation. The accounting standards update is effective prospectively for annual periods beginning on or after December 15, 2014, and interim periods within those years. Early adoption is permitted. Adoption of this standards update in the first quarter of 2015 is not expected to have an impact on our consolidated results of operations, financial position or cash flows.

MPLX_LP

MPLX LP	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interest [Abstract]	'
MPLX LP	'
	MPLX LP
	MPLX is a publicly traded master limited partnership that was formed by us to own, operate, develop and acquire pipelines and other midstream assets related to the transportation and storage of crude oil, refined products and other hydrocarbon-based products. We own a 73.6 percent interest in MPLX, including the two percent general partner interest. We consolidate this entity for financial reporting purposes since we have a controlling financial interest, and we record a noncontrolling interest for the interest owned by the public.
	MPLX’s initial assets consisted of a 51 percent general partner interest in MPLX Pipe Line Holdings LP (“Pipe Line Holdings”), which owns a network of common carrier crude oil and product pipeline systems and associated storage assets in the Midwest and Gulf Coast regions of the United States, and a 100 percent interest in a butane storage cavern in West Virginia. On May 1, 2013, we sold a five percent interest in Pipe Line Holdings to MPLX for $100 million.
	Effective March 1, 2014, we sold MPLX a 13 percent interest in Pipe Line Holdings for $310 million, increasing MPLX's ownership interest in Pipe Line Holdings to 69 percent. MPLX financed this transaction with $40 million of cash on-hand and $270 million of borrowings on its bank revolving credit agreement.
	The sales of our interests in Pipeline Holdings to MPLX resulted in a change of our ownership in Pipeline Holdings, but not a change in control. We accounted for the sales as equity transactions and did not record a gain or loss.

Acquisitions_and_Investments

Acquisitions and Investments	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Acquisitions and Investments	'
	Acquisitions and Investments
	Acquisition of Hess' Retail Operations and Related Assets
	On September 30, 2014, we acquired from Hess Corporation ("Hess") all of Hess' retail locations, transport operations and shipper history on various pipelines, including approximately 40,000 barrels per day on Colonial Pipeline for $2.82 billion. We refer to these assets as “Hess' Retail Operations and Related Assets.” The transaction was funded with a combination of debt and available cash.
	The transaction provides for an adjustment for working capital, which has not been finalized with Hess. If a change is made for working capital, the fair value of the assets acquired will be revised.
	The estimated fair values of assets acquired and liabilities assumed at the acquisition date, pending the completion of an independent appraisal and other evaluations, are as follows:
	(In millions)
	Cash and cash equivalents	$	39
	Receivables	132
	Inventories	178
	Other current assets	5
	Property, plant and equipment, net	2,062
	Other noncurrent assets	103
	Total assets acquired	2,519
	Accounts payable	77
	Payroll and benefits payable	4
	Consumer excise taxes payable	80
	Other current liabilities	10
	Defined benefit postretirement plan obligations	2
	Deferred credits and other liabilities	122
	Total liabilities assumed	295
	Net assets acquired excluding goodwill	2,224
	Goodwill	600
	Net assets acquired	$	2,824
	The purchase price allocation resulted in the recognition of $600 million in goodwill by our Speedway segment, which is deductible for tax purposes. Goodwill recognized for the acquisition primarily relates to the expected benefits of a significantly expanded retail platform that should enable growth in new markets, as well as the potential for higher merchandise sales. We also expect strategic benefits from the financial and operational scale we expect to realize across our entire retail network. This acquisition significantly expands our Speedway presence from nine to 22 states throughout the East Coast and Southeast and is aligned with our strategy to grow higher-valued, stable cash flow businesses. This acquisition also enables us to further leverage our integrated refining and transportation operations, providing an outlet for an incremental 200,000 barrels per day of assured sales from our refining system.
	Other noncurrent assets includes a $22 million intangible asset related to a trade name and $60 million related to favorable lease contract terms. Deferred credits and other liabilities includes $80 million related to unfavorable lease contract terms. The trade name is being amortized over its estimated useful life of two years based on the utilization of the assets. The favorable and unfavorable lease contract amounts are being amortized over the terms of the leases.
	We recognized $12 million of acquisition-related costs associated with Hess' Retail Operations and Related Assets acquisition. These costs were expensed and were included in selling, general and administrative expenses.
	Acquisition of Refinery and Related Logistics and Marketing Assets
	On February 1, 2013, we acquired from BP Products North America Inc. and BP Pipelines (North America) Inc. (collectively, “BP”) the 451,000 barrel per calendar day refinery in Texas City, Texas, three intrastate natural gas liquid pipelines originating at the refinery, four light product terminals, branded-jobber marketing contract assignments for the supply of approximately 1,200 branded sites, a 1,040 megawatt electric cogeneration facility and a 50,000 barrel per day allocation of space on Colonial Pipeline. We refer to these assets as the “Galveston Bay Refinery and Related Assets.” We paid $1.49 billion for these assets, which included $935 million for inventory. The transaction was funded with cash on hand. Pursuant to the purchase and sale agreement, we may also be required to pay BP a contingent earnout of up to an additional $700 million over six years, subject to certain conditions. In July 2014, we paid BP $180 million for the first period's contingent earnout. On the consolidated statements of cash flows, $172 million of the contingent earnout payment is included as a financing activity with the remainder included as an operating activity. See Note 15 for additional information on the contingent consideration.
	The following unaudited pro forma financial information presents consolidated results assuming the Galveston Bay Refinery and Related Assets acquisition occurred on January 1, 2012 and Hess' Retail Operations and Related Assets acquisition occurred on January 1, 2013. The pro forma financial information does not give effect to potential synergies that could result from the acquisitions and is not necessarily indicative of the results of future operations.
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions, except per share data)	2014		2013		2014		2013
	Sales and other operating revenues (including consumer excise taxes)	$	28,284	$	29,317	$	84,232	$	86,386
	Net income attributable to MPC	698		170		1,748		1,516
	Net income attributable to MPC per share - basic	$	2.48	$	0.55	$	6.07	$	4.72
	Net income attributable to MPC per share - diluted	2.46		0.55		6.03		4.69
	The pro forma information includes adjustments to align accounting policies, an adjustment to depreciation expense to reflect the fair value of property, plant and equipment, increased amortization expense related to identifiable intangible assets, additional interest expense related to financing the acquisition of Hess' Retail Operations and Related Assets, as well as the related income tax effects.
	Acquisitions of Convenience Stores
	During 2013, Speedway acquired nine convenience stores located in Tennessee, western Indiana and western Pennsylvania. In connection with these acquisitions, our Speedway segment recorded $8 million of goodwill, which is deductible for income tax purposes.
	The principal factors contributing to a purchase price resulting in goodwill included the acquired stores complementing our existing network in our Midwest market, access to our refined product transportation systems and the potential for higher merchandise sales.
	Acquisition of Biodiesel Facility
	On April 1, 2014, we purchased a facility in Cincinnati, Ohio from Felda Iffco Sdn Bhd, Malaysia for $40 million. The plant currently produces biodiesel, glycerin and other by-products. The capacity of the plant is approximately 60 million gallons per year.
	Neither goodwill nor a gain from a bargain purchase was recognized in conjunction with the biodiesel facility acquisition.
	Assuming the acquisitions of the convenience stores in 2013 and the biodiesel facility in 2014 had been made at the beginning of any period presented, the consolidated pro forma results would not be materially different from reported results.
	Investments in Ethanol Companies
	On August 1, 2013, we acquired from Mitsui & Co. (U.S.A.), Inc. its interests in three ethanol companies for $75 million. Under the purchase agreement, we acquired an additional 24 percent interest in The Andersons Clymers Ethanol LLC ("TACE"), bringing our ownership interest to 60 percent; a 34 percent interest in The Andersons Ethanol Investment LLC ("TAEI"), which holds a 50 percent ownership in The Andersons Marathon Ethanol LLC ("TAME"), bringing our direct and indirect ownership interest in TAME to 67 percent; and a 40 percent interest in The Andersons Albion Ethanol LLC ("TAAE"), which owns an ethanol production facility in Albion, Michigan. On October 1, 2013, our ownership interest in TAAE increased to 43 percent as a result of TAAE acquiring one of the owner's interest. We hold a noncontrolling interest in each of these entities and account for them using the equity method of accounting since the minority owners have substantive participating rights.
	Investments in Pipeline Companies
	In July 2014, we exercised our option to acquire a 35 percent ownership interest in Enbridge Inc.'s Southern Access Extension pipeline ("SAX") through our investment in Illinois Extension Pipeline Company, LLC ("Illinois Extension Pipeline"). During the nine months ended September 30, 2014, we made contributions of $97 million to Illinois Extension Pipeline to fund our portion of the construction costs incurred-to-date on the SAX project. We account for our ownership interest in Illinois Extension Pipeline as an equity method investment. See Note 22 for information on future contributions to Illinois Extension Pipeline.
	In March 2014, we acquired from Chevron Raven Ridge Pipe Line Company an additional seven percent interest in Explorer Pipeline Company ("Explorer") for $77 million, bringing our ownership interest to 25 percent. As a result of this increase in our ownership, we now account for our investment in Explorer using the equity method of accounting rather than the cost method. The cumulative impact of the change was applied as an adjustment to 2014 retained earnings.
	In November 2013, we agreed to serve as an anchor shipper for the Sandpiper pipeline project and fund 37.5 percent of the construction costs of the project, which will become part of Enbridge Energy Partners L.P.'s ("Enbridge Energy Partners") North Dakota System. In exchange for these commitments, we will earn an approximate 27 percent equity interest in Enbridge Energy Partners' North Dakota System when the Sandpiper pipeline is placed into service. We also have the option to increase our ownership interest to approximately 30 percent through additional investments in future system improvements. We made contributions of $149 million to North Dakota Pipeline Company LLC ("North Dakota Pipeline") during the nine months ended September 30, 2014. We have contributed $173 million since project inception. We account for our interest in North Dakota Pipeline using the equity method of accounting. See Note 22 for information on future contributions to North Dakota Pipeline.

Variable_Interest_Entity

Variable Interest Entity	9 Months Ended
	Sep. 30, 2014
Variable Interest Entity [Abstract]	'
Variable Interest Entity Disclosure	'
	Variable Interest Entity
	As stated in Note 4, we have a 35 percent ownership interest in Illinois Extension Pipeline through our contributions to the SAX project. Illinois Extension Pipeline Company LLC is considered a variable interest entity ("VIE") because it is a development stage entity and the equity in the entity is not sufficient to fund the current stage of development, which is the construction of the SAX pipeline. Our maximum exposure to loss due to this VIE at September 30, 2014 was $97 million, which equates to our contributions to-date to fund our portion of the construction costs for the project.
	We are not the primary beneficiary of this VIE and, therefore, do not consolidate it because we do not have the power to control the activities that significantly influence the economic activities of the entity. The activities that most significantly impact the VIE's economic performance during the construction phase are the actual construction costs and risks associated with the construction process. Through our vote, we have shared power to direct the construction activities, but do not have the sole ability to control the construction activities.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2014
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	Related Party Transactions
	Our related parties include:
	•	Centennial Pipeline LLC (“Centennial”), in which we have a 50 percent noncontrolling interest. Centennial owns a refined products pipeline and storage facility.
	•	Explorer, in which we have a 25 percent interest. Explorer owns and operates a refined products pipeline.
	•	LOCAP LLC ("LOCAP"), in which we have a 59 percent noncontrolling interest. LOCAP owns and operates a crude oil pipeline.
	•	LOOP LLC (“LOOP”), in which we have a 51 percent noncontrolling interest. LOOP owns and operates the only U.S. deepwater oil port.
	•	TAAE, in which we have a 43 percent noncontrolling interest, TACE, in which we have a 60 percent noncontrolling interest and TAME, in which we have a 67 percent direct and indirect noncontrolling interest. These companies each own an ethanol production facility.
	•	Other equity method investees.
	Sales to related parties, which are included in sales and other operating revenues (including consumer excise taxes) on the consolidated statements of income, were as follows:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions)	2014		2013		2014		2013
	Other equity method investees	$	2	$	3	$	6	$	7
	Fees received for operating Centennial's pipeline, which are included in other income on the consolidated statements of income, were $1 million for the nine months ended September 2014 and 2013.
	Purchases from related parties were as follows:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions)	2014		2013		2014		2013
	Centennial	$	—	$	4	$	7	$	4
	Explorer	10		—		32		—
	LOCAP	6		5		16		13
	LOOP	12		11		77		32
	TAAE	19		8		61		8
	TACE	33		42		90		92
	TAME	29		31		111		98
	Other equity method investees	3		2		7		7
	Total	$	112	$	103	$	401	$	254
	Related party purchases from Centennial consist primarily of refinery feedstocks and refined product transportation costs. Related party purchases from Explorer consist primarily of refined product transportation costs. Related party purchases from LOCAP, LOOP and other equity method investees consist primarily of crude oil transportation costs and crude oil purchases. Related party purchases from TAAE, TACE and TAME consist of ethanol purchases.
	Receivables from related parties, which are included in receivables, less allowance for doubtful accounts on the consolidated balance sheets, were as follows:
	(In millions)	September 30,		December 31,
		2014		2013
	Centennial	$	2	$	1
	TAME	2		1
	Total	$	4	$	2
	We also had a long-term receivable from Centennial of $1 million at September 30, 2014 and of $2 million at December 31, 2013, which is included in other noncurrent assets on the consolidated balance sheets.
	Payables to related parties, which are included in accounts payable on the consolidated balance sheets, were as follows:
	(In millions)	September 30,		December 31,
		2014		2013
	Explorer	$	5	$	—
	LOCAP	2		2
	LOOP	4		3
	TAAE	1		2
	TACE	2		4
	TAME	2		5
	Other equity method investees	1		—
	Total	$	17	$	16

Income_per_Common_Share

Income per Common Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Income per Common Share	'
	Income per Common Share
	We compute basic earnings per share by dividing net income attributable to MPC by the weighted average number of shares of common stock outstanding. Diluted income per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive.
	MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities. Due to the presence of participating securities, we have calculated our earnings per share using the two-class method.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions, except per share data)	2014			2013			2014		2013
	Basic earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	672		$	168		$	1,726	$	1,486
	Income allocated to participating securities	1			—			3		2
	Income available to common stockholders - basic	$	671		$	168		$	1,723	$	1,484
	Weighted average common shares outstanding	282			309			288		321
	Basic earnings per share	$	2.38		$	0.54		$	5.99	$	4.63
	Diluted earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	672		$	168		$	1,726	$	1,486
	Income allocated to participating securities	1			—			3		2
	Income available to common stockholders - diluted	$	671		$	168		$	1,723	$	1,484
	Weighted average common shares outstanding	282			309			288		321
	Effect of dilutive securities	2			2			2		2
	Weighted average common shares, including dilutive effect	284			311			290		323
	Diluted earnings per share	$	2.36		$	0.54		$	5.95	$	4.6
	The following table summarizes the shares that were anti-dilutive and, therefore, were excluded from the diluted share calculation.
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
	(In millions)	2014		2013			2014		2013
	Shares issued under stock-based compensation plans	—		1			—		1

Equity

Equity	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Equity	'
	Equity
	On July 30, 2014, our board of directors approved an additional $2.0 billion share repurchase authorization expiring in July 2016. As of September 30, 2014, our board of directors had approved $8.0 billion in total share repurchase authorizations since January 1, 2012 and we have repurchased a total of $5.59 billion of our common stock, leaving $2.41 billion available for repurchases. Under these authorizations, we have acquired 82 million shares at an average cost per share of $68.41.
	We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, 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 three and nine months ended September 30, 2014 and 2013:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions, except per share data)	2014		2013		2014		2013
	Number of shares repurchased(a)	4		14		17		31
	Cash paid for shares repurchased	$	301	$	1,028	$	1,449	$	2,341
	Effective average cost per delivered share	$	85.15	$	70.73	$	87.25	$	76.01
	(a)	The nine months ended September 30, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in 2012.
	At September 30, 2014, we had agreements to acquire additional common shares for $9 million, which were settled in early October 2014.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	We have three reportable segments: Refining & Marketing; Speedway; and Pipeline Transportation. Each of these segments is organized and managed based upon the nature of the products and services it offers.
	•	Refining & Marketing – refines crude oil and other feedstocks at our refineries in the Gulf Coast and Midwest regions of the United States, purchases ethanol and refined products for resale and distributes refined products through various means, including barges, terminals and trucks that we own or operate. We sell refined products to wholesale marketing customers domestically and internationally, to buyers on the spot market, to our Speedway segment and to independent entrepreneurs who operate Marathon® retail outlets.
	•	Speedway – with the acquisition of Hess' retail operations effective September 30, 2014, sells transportation fuels and convenience products in retail markets in the Midwest, East Coast and Southeast.
	•	Pipeline Transportation – transports crude oil and other feedstocks to our refineries and other locations, delivers refined products to wholesale and retail market areas and includes the aggregated operations of MPLX and MPC’s retained pipeline assets and investments.
	On February 1, 2013, we acquired the Galveston Bay Refinery and Related Assets, which are part of the Refining & Marketing and Pipeline Transportation segments. On September 30, 2014, we acquired Hess' Retail Operations and Related Assets, which are part of the Speedway and Refining & Marketing segments. Segment information for the periods prior to each acquisition do not include amounts for these operations. See Note 4.
	Segment income represents income from operations attributable to the reportable segments. Corporate administrative expenses and costs related to certain non-operating assets are not allocated to the reportable 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			Speedway			Pipeline Transportation			Total
	Three Months Ended September 30, 2014
	Revenues:
	Customer	$	21,568		$	3,854		$	16		$	25,438
	Intersegment(a)	2,400			2			136			2,538
	Segment revenues	$	23,968		$	3,856		$	152		$	27,976
	Segment income from operations(b)	$	971		$	119		$	69		$	1,159
	Income from equity method investments	17			—			12			29
	Depreciation and amortization(c)	257			33			20			310
	Capital expenditures and investments(d)(f)	318			2,707			224			3,249
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Three Months Ended September 30, 2013
	Revenues:
	Customer	$	22,481		$	3,755		$	20		$	26,256
	Intersegment(a)	2,439			1			117			2,557
	Segment revenues	$	24,920		$	3,756		$	137		$	28,813
	Segment income from operations(b)	$	227		$	102		$	54		$	383
	Income from equity method investments	8			—			1			9
	Depreciation and amortization(c)	246			29			19			294
	Capital expenditures and investments(d)	243			65			42			350
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Nine Months Ended September 30, 2014
	Revenues:
	Customer	$	64,295		$	11,220		$	52		$	75,567
	Intersegment(a)	7,223			4			396			7,623
	Segment revenues	$	71,518		$	11,224		$	448		$	83,190
	Segment income from operations(b)	$	2,593		$	271		$	222		$	3,086
	Income from equity method investments	76			—			45			121
	Depreciation and amortization(c)	782			90			58			930
	Capital expenditures and investments(d)(f)	731			2,783			418			3,932
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Nine Months Ended September 30, 2013
	Revenues:
	Customer	$	64,245		$	10,964		$	60		$	75,269
	Intersegment(a)	7,072			3			340			7,415
	Segment revenues	$	71,317		$	10,967		$	400		$	82,684
	Segment income from operations(b)	$	2,235		$	292		$	163		$	2,690
	Income from equity method investments	7			—			9			16
	Depreciation and amortization(c)	734			83			55			872
	Capital expenditures and investments(d)(e)	1,797			177			173			2,147
	(a)	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.
	(b)	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
	(c)	Differences between segment totals and MPC totals represent amounts related to unallocated items and are included in “Items not allocated to segments” in the reconciliation below.
	(d)	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
	(e)	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4.
	(f)	The Speedway and Refining & Marketing segments include $2.63 billion and $54 million, respectively, for the acquisition of Hess' Retail Operations and Related Assets. See Note 4.
	The following reconciles segment income from operations to income before income taxes as reported in the consolidated statements of income:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Segment income from operations	$	1,159		$	383		$	3,086		$	2,690
	Items not allocated to segments:
	Corporate and other unallocated items(a)(b)	(76		)	(59		)	(204		)	(190		)
	Pension settlement expenses(c)	(21		)	(23		)	(90		)	(83		)
	Net interest and other financial income (costs)	(50		)	(47		)	(144		)	(140		)
	Income before income taxes	$	1,012		$	254		$	2,648		$	2,277
(a)	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets.
(b)	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
(c)	See Note 20.
The following reconciles segment capital expenditures and investments to total capital expenditures:
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
(In millions)	2014			2013			2014			2013
Segment capital expenditures and investments	$	3,249		$	350		$	3,932		$	2,147
Less: Investments in equity method investees	177			75			341			86
Plus: Items not allocated to segments:
Capital expenditures not allocated to segments	22			54			60			106
Capitalized interest	7			7			20			15
Total capital expenditures(a)(b)	$	3,101		$	336		$	3,671		$	2,182
(a)	Capital expenditures include changes in capital accruals and acquisitions.
(b)	See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
The following reconciles customer revenues to sales and other operating revenues (including consumer excise taxes) as reported in the consolidated statements of income:
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
(In millions)	2014			2013			2014			2013
Customer revenues (as reported above)	$	25,438		$	26,256		$	75,567		$	75,269
Corporate and other unallocated items	—			—			—			(6		)
Sales and other operating revenues (including consumer excise taxes)	$	25,438		$	26,256		$	75,567		$	75,263
Total assets by reportable segment were:
(In millions)	September 30,			December 31, 2013
	2014
Refining & Marketing	$	20,207		$	19,573
Speedway	5,203			2,064
Pipeline Transportation	2,329			1,947
Corporate and Other	3,966			4,801
Total consolidated assets	$	31,705		$	28,385

Other_Items

Other Items	9 Months Ended
	Sep. 30, 2014
Other Income and Expenses [Abstract]	'
Other Items	'
	Other Items
	Net interest and other financial income (costs) was:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Interest:
	Interest income	$	2		$	2		$	5		$	7
	Interest expense	(56		)	(50		)	(154		)	(147		)
	Interest capitalized	7			7			20			15
	Total net interest	(47		)	(41		)	(129		)	(125		)
	Other:
	Net foreign currency gains (losses)	1			(1		)	—			—
	Bank service and other fees	(4		)	(5		)	(15		)	(15		)
	Total other	(3		)	(6		)	(15		)	(15		)
	Net interest and other financial income (costs)	$	(50	)	$	(47	)	$	(144	)	$	(140	)

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The combined federal, state and foreign income tax rate was 33 percent and 32 percent for the three months ended September 30, 2014 and 2013, respectively, and 34 percent for both the nine months ended September 30, 2014 and 2013. The effective tax rate for the three and nine months ended September 30, 2014 and 2013 is slightly less than the U.S. statutory rate of 35 percent primarily due to certain permanent benefit differences, including the domestic manufacturing deduction, partially offset by state and local tax expense.
	Prior to the June 30, 2011 spinoff transaction from Marathon Oil Corporation (“Marathon Oil”), we were included in Marathon Oil’s income tax returns for all applicable years. During 2011, we anticipated a future settlement between Marathon Oil and us upon the filing of Marathon Oil’s consolidated U.S. federal and state income tax returns for the period prior to June 30, 2011. During the second quarter of 2013, we settled with Marathon Oil for the 2011 period based on filed tax returns, resulting in a $39 million increase to additional paid-in capital.
	We are continuously undergoing examination of our income tax returns, which have been completed for our U.S. federal and state income tax returns through the 2009 and 2003 tax years, respectively. We had $16 million of unrecognized tax benefits as of September 30, 2014. 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	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	(In millions)	September 30,		December 31,
		2014		2013
	Crude oil and refinery feedstocks	$	2,405	$	1,797
	Refined products	2,731		2,367
	Materials and supplies	308		425
	Merchandise	164		100
	Total (at cost)	$	5,608	$	4,689
	Inventories are carried at the lower of cost or market value. The cost of inventories of crude oil and refinery feedstocks, refined products and merchandise is determined primarily under the last-in, first-out (“LIFO”) method. There were no liquidations of LIFO inventories for the nine months ended September 30, 2014 and 2013.

Property_Plant_and_Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2014
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	Property, Plant and Equipment
	(In millions)	September 30,		December 31,
		2014		2013
	Refining & Marketing	$	17,646	$	16,982
	Speedway	4,477		2,344
	Pipeline Transportation	1,995		1,921
	Corporate and Other	594		546
	Total	24,712		21,793
	Less accumulated depreciation	8,713		7,872
	Property, plant and equipment, net	$	15,999	$	13,921

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill	'
	Goodwill
	The changes in the carrying amount of goodwill for nine months ended September 30, 2014 were as follows:
	(In millions)	Refining & Marketing			Speedway		Pipeline Transportation		Total
	Balance as of December 31, 2013	$	551		$	225	$	162	$	938
	Acquisition(a)	—			600		—		600
	Disposition	(1		)	—		—		(1		)
	Balance as of September 30, 2014	$	550		$	825	$	162	$	1,537
	(a)	See Note 4 for information on the acquisitions.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013 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.
		September 30, 2014
		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
	Commodity derivative instruments, assets	$	87		$	—		$	—		$	(55	)	$	32	$	60
	Other assets	2			—			—			N/A			2		—
	Total assets at fair value	$	89		$	—		$	—		$	(55	)	$	34	$	60
	Commodity derivative instruments, liabilities	$	55		$	—		$	—		$	(55	)	$	—	$	—
	Contingent consideration, liability(c)	—			—			475			N/A			475		—
	Total liabilities at fair value	$	55		$	—		$	475		$	(55	)	$	475	$	—
		December 31, 2013
		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
	Commodity derivative instruments, assets	$	21		$	—		$	—		$	(21	)	$	—	$	61
	Other assets	2			—			—			N/A			2		—
	Total assets at fair value	$	23		$	—		$	—		$	(21	)	$	2	$	61
	Commodity derivative instruments, liabilities	$	53		$	—		$	—		$	(53	)	$	—	$	—
	Contingent consideration, liability(c)	—			—			625			N/A			625		—
	Total liabilities at fair value	$	53		$	—		$	625		$	(53	)	$	625	$	—
	(a)	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of September 30, 2014 and December 31, 2013, cash collateral of $0 million and $32 million, respectively, was netted with mark-to-market derivative liabilities.
	(b)	We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.
	(c)	Includes $193 million and $159 million classified as current at September 30, 2014 and December 31, 2013, respectively.
	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.
	The contingent consideration represents the fair value as of September 30, 2014 of the amount we expect to pay to BP related to the earnout provision for the Galveston Bay Refinery and Related Assets acquisition. See Note 4. The fair value of the contingent consideration was estimated using an income approach and is therefore a Level 3 liability. The amount of cash to be paid under the arrangement is based on both a market-based crack spread and refinery throughput volumes for the months during which the contract applies, as well as established thresholds that cap the annual and total payment. The earnout payment cannot exceed $200 million per year for the first three years of the arrangement or $250 million per year for the last three years of the arrangement, with the total cumulative payment capped at $700 million over the six-year period. Any excess or shortfall from the annual cap for a current year’s earnout calculation will not affect subsequent years’ calculations. The fair value calculation used significant unobservable inputs, including (1) an estimate of refinery throughput volumes; (2) a range of internal and external crack spread forecasts from $14 to $15 per barrel; and (3) a range of risk-adjusted discount rates from five percent to 10 percent. An increase or decrease in crack spread forecasts or refinery throughput volume expectations may result in a corresponding increase or decrease in the fair value. Increases to the fair value as a result of increasing forecasts for both of these unobservable inputs, however, are limited as the earnout payment is subject to annual caps. An increase or decrease in the discount rate may result in a decrease or increase to the fair value, respectively. The fair value of the contingent consideration is reassessed each quarter, with changes in fair value recorded in cost of revenues.
	The following is a reconciliation of the beginning and ending balances recorded for liabilities classified as Level 3 in the fair value hierarchy.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Beginning balance	$	647		$	611		$	625		$	—
	Contingent consideration agreement	—			—			—			600
	Contingent consideration payment	(180		)	—			(180		)	—
	Unrealized (gains) losses included in net income	8			(5		)	30			6
	Ending balance	$	475		$	606		$	475		$	606
	We did not hold any Level 3 derivative instruments during the three and nine months ended September 30, 2014 and 2013. See Note 16 for the income statement impacts of our derivative instruments.
	Fair Values – Nonrecurring
	The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition.
		Nine Months Ended September 30,
		2014						2013
	(In millions)	Fair Value			Impairment			Fair Value			Impairment
	Property, plant and equipment, net	$	—		$	—		$	1		$	8
	Other noncurrent assets	—			11			—			—
	Based on the financial and operational status of a company in which we have an interest, we fully impaired our $11 million investment in that company during the second quarter of 2014. Our investment in this company was accounted for using the cost method and was included in our Refining & Marketing segment. The impairment is included in other income on the consolidated statements of income. The fair value of our investment in this cost company was measured using an income approach. This measurement is classified as Level 3.
	Due to changing market conditions, we assessed one of our light products terminals for impairment. The terminal is operated by our Refining & Marketing segment. We recorded an impairment charge of $8 million for this terminal in 2013. The impairment is included in depreciation and amortization on the consolidated statements of income. The fair value of the terminal was measured using a market approach based on comparable area property values, which are Level 3 inputs.
	Fair Values – Reported
	The following table summarizes financial instruments on the basis of their nature, characteristics and risk at September 30, 2014 and December 31, 2013, excluding the derivative financial instruments and contingent consideration reported above.
		September 30, 2014						December 31, 2013
	(In millions)	Fair Value			Carrying Value			Fair Value			Carrying Value
	Financial assets:
	Investments	$	23		$	2		$	336		$	14
	Other	31			29			31			30
	Total financial assets	$	54		$	31		$	367		$	44
	Financial liabilities:
	Long-term debt(a)	$	6,224		$	5,886		$	3,306		$	3,001
	Deferred credits and other liabilities	20			20			21			21
	Total financial liabilities	$	6,244		$	5,906		$	3,327		$	3,022
	(a)	Excludes capital leases
	Our current assets and liabilities include financial instruments, the most significant of which are trade accounts receivable and payables. We believe the carrying values of our current assets and liabilities approximate fair value. Our fair value assessment incorporates a variety of considerations, including (1) the short-term duration of the instruments, (2) our investment-grade credit rating and (3) our historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk.
	Fair values of our financial assets included in investments and other financial assets and of our financial liabilities included in deferred credits and other liabilities are measured primarily using an income approach and most inputs are internally generated, which results in a Level 3 classification. Estimated future cash flows are discounted using a rate deemed appropriate to obtain the fair value. Other financial assets primarily consist of environmental remediation receivables. Deferred credits and other liabilities primarily consist of insurance liabilities and environmental remediation liabilities.
	Fair value of fixed-rate long-term debt is measured using a market approach, based upon the average of quotes from major financial institutions and a third-party service for our debt. Because these quotes cannot be independently verified to the market, they are considered Level 3 inputs. Fair value of variable-rate long-term debt approximates the carrying value.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2014
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 and (4) the acquisition of ethanol for blending with refined products.
	The following table presents the gross fair values of derivative instruments, excluding cash collateral, and where they appear on the consolidated balance sheets as of September 30, 2014 and December 31, 2013:
		September 30, 2014
	(In millions)	Asset				Liability			Balance Sheet Location
	Commodity derivatives	$	87			$	55		Other current assets
		December 31, 2013
	(In millions)	Asset				Liability			Balance Sheet Location
	Commodity derivatives	$	21			$	53		Other current assets
	The table below summarizes open commodity derivative contracts as of September 30, 2014.
		Position		Total Barrels (In thousands)
	Crude oil(a)
	Exchange-traded	Long		10,346
	Exchange-traded	Short		(23,186	)
	Refined Products(b)
	Exchange-traded	Long		1,695
	Exchange-traded	Short		(3,281	)
	(a)	96 percent of these contracts expire in the fourth quarter of 2014.
	(b)	100 percent of these contracts expire in the fourth quarter of 2014.
	The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income:
		Gain (Loss)							Gain (Loss)
	(In millions)	Three Months Ended September 30,							Nine Months Ended September 30,
	Income Statement Location	2014				2013			2014			2013
	Sales and other operating revenues	$	10			$	9		$	18		$	13
	Cost of revenues	145				(170		)	(30		)	(179		)
	Total	$	155			$	(161	)	$	(12	)	$	(166	)

Debt

Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	Our outstanding borrowings at September 30, 2014 and December 31, 2013 consisted of the following:
	(In millions)	September 30,			December 31,
		2014			2013
	Marathon Petroleum Corporation:
	Revolving credit agreement due 2017	$	—		$	—
	Term loan agreement due 2019	700			—
	3.500% senior notes due March 1, 2016	750			750
	5.125% senior notes due March 1, 2021	1,000			1,000
	3.625% senior notes due September 15, 2024	750			—
	6.500% senior notes due March 1, 2041	1,250			1,250
	4.750% senior notes due September 15, 2044	800			—
	5.000% senior notes due September 15, 2054	400			—
	Consolidated subsidiaries:
	Capital lease obligations due 2014-2028	378			395
	MPLX Operations LLC revolving credit agreement due 2017	255			—
	Trade receivables securitization facility due 2016	—			—
	Total	6,283			3,395
	Unamortized discount	(26		)	(10		)
	Fair value adjustments(a)	7			11
	Amounts due within one year	(26		)	(23		)
	Total long-term debt due after one year	$	6,238		$	3,373
	(a)	The $20 million gain on the termination of our interest rate swap agreements in 2012 is being amortized over the remaining life of the 3.50 percent senior notes.
	There were no borrowings or letters of credit outstanding under the MPC revolving credit agreement or the trade receivables securitization facility at September 30, 2014. During the nine months ended September 30, 2014, MPLX borrowed $270 million under the MPLX Operations LLC revolving credit agreement (the "MPLX Credit Agreement"), at an average interest rate of 1.5 percent, per annum, and repaid $15 million of these borrowings. The borrowings were used to fund MPLX's March 2014 acquisition of an additional interest in Pipe Line Holdings. At September 30, 2014, MPLX had $255 million of borrowings and no letters of credit outstanding under the MPLX Credit Agreement, resulting in total unused loan availability of $245 million, or 49 percent of the borrowing capacity. The MPLX Credit Agreement is scheduled to mature on October 31, 2017.
	Term Loan Agreement
	On August 26, 2014, we entered into a $700 million five-year senior unsecured term loan credit agreement (the “Term Loan Agreement”) with a syndicate of lenders to fund a portion of the purchase price for the acquisition of Hess' Retail Operations and Related Assets. The Term Loan Agreement matures on September 24, 2019 and may be prepaid at any time without premium or penalty. We are obligated to pay certain customary fees under the Term Loan Agreement, including an annual administrative fee.
	Amounts outstanding under the Term Loan Agreement bear interest at either of the following rates at our election (i) the sum of the Adjusted LIBO Rate (as defined in the Term Loan Agreement), plus a margin ranging between 0.875 percent to 1.75 percent, depending on our credit ratings, or (ii) the sum of the Base Rate (as defined in the Term Loan Agreement), plus a margin ranging between zero percent to 0.75 percent, depending on our credit ratings. The interest rate during the quarter ended September 30, 2014 was 1.3 percent.
	The Term Loan Agreement contains representation and warranties, covenants and events of default that are substantially similar to those contained in the MPC revolving credit agreement, including a financial covenant, which requires us to maintain, as of the last day of each fiscal quarter, a ratio of Consolidated Net Debt to Total Capitalization (as defined in the Term Loan Agreement) of no greater than 0.65 to 1.00.
	Senior Notes
	On September 5, 2014, we completed a public offering of $1.95 billion in aggregate principal amount of senior unsecured notes (the "Senior Notes"), consisting of $750 million aggregate principal amount of our Senior Notes due 2024, $800 million aggregate principal amount of our Senior Notes due 2044 and $400 million aggregate principal amount of our Senior Notes due 2054. The net proceeds from the offering of the Senior Notes were approximately $1.915 billion, after deducting underwriting discounts and estimated offering expenses. The proceeds were used to fund a portion of the purchase price for the acquisition of Hess' Retail Operations and Related Assets. Interest on each series of Senior Notes is payable semi-annually in arrears on March 15 and September 15 of each year, commencing on March 15, 2015.
	The Senior Notes are unsecured and unsubordinated obligations of ours and rank equally with all our other existing and future unsecured and unsubordinated indebtedness.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
	Supplemental Cash Flow Information
		Nine Months Ended
		September 30,
	(In millions)	2014		2013
	Net cash provided by operating activities included:
	Interest paid (net of amounts capitalized)	$	162	$	166
	Net income taxes paid to taxing authorities	969		1,027
	Non-cash investing and financing activities:
	Capital lease obligations increase	$	—	$	61
	Property, plant and equipment sold	4		43
	Property, plant and equipment acquired	4		—
	Acquisition:
	Contingent consideration(a)	—		600
	Payable to seller(a)	—		6
	(a)	Acquisition-date fair value of non-cash consideration associated with the Galveston Bay Refinery and Related Assets acquisition.
	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:
		Nine Months Ended
		September 30,
	(In millions)	2014		2013
	Additions to property, plant and equipment per consolidated statements of cash flows	$	952	$	733
	Non-cash additions to property, plant and equipment	4		—
	Acquisitions(a)	2,714		1,386
	Asset retirement expenditures	1		—
	Increase in capital accruals	—		63
	Total capital expenditures	$	3,671	$	2,182
	(a)	The 2014 acquisition includes the acquisition of Hess' Retail Operations and Related Assets. The 2013 acquisition includes the acquisition of the Galveston Bay Refinery and Related Assets. The acquisition numbers above include property, plant and equipment and intangibles. See Note 4.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2014
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, 2012	$	(432	)	$	(36	)	$	4	$	—		$	(464	)
	Other comprehensive income before reclassifications	172			3			—		2			177
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(34		)	(3		)	—		—			(37		)
	– actuarial loss(a)	53			2			—		—			55
	– settlement loss(a)	83			—			—		—			83
	Tax effect	(19		)	—			—		—			(19		)
	Other comprehensive income	255			2			—		2			259
	Balance as of September 30, 2013	$	(177	)	$	(34	)	$	4	$	2		$	(205	)
	(In millions)	Pension Benefits			Other Benefits			Gain on Cash Flow Hedge		Workers Compensation			Total
	Balance as of December 31, 2013	$	(161	)	$	(50	)	$	4	$	3		$	(204	)
	Other comprehensive income (loss) before reclassifications	(88		)	8			—		(2		)	(82		)
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(35		)	(3		)	—		—			(38		)
	– actuarial loss(a)	38			2			—		—			40
	– settlement loss(a)	90			—			—		—			90
	Tax effect	(35		)	1			—		—			(34		)
	Other comprehensive income (loss)	(30		)	8			—		(2		)	(24		)
	Balance as of September 30, 2014	$	(191	)	$	(42	)	$	4	$	1		$	(228	)
	(a)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 20.

Defined_Benefit_Pension_and_Ot

Defined Benefit Pension and Other Postretirement Plans	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Defined Benefit Pension and Other Postretirement Plans	'
	Defined Benefit Pension and Other Postretirement Plans
	The following summarizes the components of net periodic benefit costs:
		Three Months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	24		$	24		$	7		$	7
	Interest cost	18			19			7			6
	Expected return on plan assets	(27		)	(28		)	—			—
	Amortization – prior service credit	(12		)	(12		)	(1		)	(1		)
	– actuarial loss	12			14			1			1
	– settlement loss	21			23			—			—
	Net periodic benefit cost	$	36		$	40		$	14		$	13
		Nine Months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	67		$	70		$	20		$	19
	Interest cost	56			55			24			19
	Expected return on plan assets	(81		)	(81		)	—			—
	Amortization – prior service credit	(35		)	(34		)	(3		)	(3		)
	– actuarial loss	38			53			2			2
	– settlement loss	90			83			—			—
	Net periodic benefit cost	$	135		$	146		$	43		$	37
	During the nine months ended September 30, 2014, we made contributions of $16 million to our funded pension plans. Current benefit payments related to unfunded pension and other postretirement benefit plans were $22 million and $17 million, respectively, during the nine months ended September 30, 2014.
	During the nine months ended September 30, 2014 and 2013, we determined that lump sum payments to employees retiring in the respective years will exceed the plans’ total service and interest costs for the year. Settlement losses are required to be recorded when lump sum payments exceed total service and interest costs. As a result, during the nine months ended September 30, 2014 and 2013, we recorded pension settlement expenses of $90 million and $83 million related to our cumulative lump sum payments made during the first nine months of 2014 and 2013, respectively.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Compensation Plans	'
	Stock-Based Compensation Plans
	Stock Option Awards
	The following table presents a summary of our stock option award activity for the nine months ended September 30, 2014:
		Number of Shares(a)		Weighted Average Exercise Price
	Outstanding at December 31, 2013	5,147,837		$	40.08
	Granted	446,310		85.02
	Exercised	(696,159	)	32.12
	Forfeited, canceled or expired	(20,761	)	49.67
	Outstanding at September 30, 2014	4,877,227		45.28
	(a)	Includes an immaterial number of stock appreciation rights.
	The grant date fair value of stock option awards granted during the nine months ended September 30, 2014 was $25.37 per share. The fair value of stock options granted to our employees is estimated on the date of the grant using the Black Scholes option-pricing model, which employs various assumptions. Beginning in the first quarter of 2014, the assumption for expected volatility of our stock price was refined to reflect a weighting of 50 percent of MPC’s common stock implied volatility and 50 percent of MPC's common stock historical volatility.
	Restricted Stock Awards
	The following table presents a summary of restricted stock award activity for the nine months ended September 30, 2014:
		Shares of Restricted Stock ("RS")				Restricted Stock Units ("RSU")
		Number of Shares		Weighted Average Grant Date Fair Value		Number of Units		Weighted Average Grant Date Fair Value
	Outstanding at December 31, 2013	624,122		$	61.11	385,079		$	33.96
	Granted	240,882		87.81		19,827		86.79
	RS's Vested/RSU's Issued	(324,697	)	55.47		(398	)	60.11
	Forfeited	(25,943	)	70.1		(133	)	76.1
	Outstanding at September 30, 2014	514,364		76.73		404,375		36.51
	Performance Unit Awards
	The following table presents a summary of the activity for performance unit awards to be settled in shares for the nine months ended September 30, 2014:
		Number of Units
	Outstanding at December 31, 2013	3,822,500
	Granted	2,033,700
	Settled	—
	Canceled	—
	Outstanding at September 30, 2014	5,856,200
	The performance unit awards granted in 2014 have a grant date fair value of $0.85 per unit, as calculated using a Monte Carlo valuation model.
	MPLX Awards
	During the nine months ended September 30, 2014, MPLX granted equity-based compensation awards under the MPLX LP 2012 Incentive Compensation Plan. The compensation expense for these awards is not material to our consolidated financial statements.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
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, including those resulting from the acquisition of Hess' Retail Operations and Related Assets. For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings and discovery. 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 September 30, 2014 and December 31, 2013, accrued liabilities for remediation totaled $182 million and $123 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, was $71 million and $51 million at September 30, 2014 and December 31, 2013, respectively.
	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.
	Lawsuits—In May 2007, the Kentucky attorney general filed a lawsuit against us and Marathon Oil in state court in Franklin County, Kentucky for alleged violations of Kentucky’s emergency pricing and consumer protection laws following Hurricanes Katrina and Rita in 2005. The lawsuit alleges that we overcharged customers by $89 million during September and October 2005. The complaint seeks disgorgement of these sums, as well as penalties, under Kentucky’s emergency pricing and consumer protection laws. We are vigorously defending this litigation. We believe that this is the first lawsuit for damages and injunctive relief under the Kentucky emergency pricing laws to progress this far and it contains many novel issues. In May 2011, the Kentucky attorney general amended his complaint to include a request for immediate injunctive relief as well as unspecified damages and penalties related to our wholesale gasoline pricing in April and May 2011 under statewide price controls that were activated by the Kentucky governor on April 26, 2011 and which have since expired. The court denied the attorney general’s request for immediate injunctive relief, and the remainder of the 2011 claims likely will be resolved along with those dating from 2005. If the lawsuit is resolved unfavorably in its entirety, it could materially impact our consolidated results of operations, financial position or cash flows. However, management does not believe the ultimate resolution of this litigation will have a material adverse effect.
	We are a defendant in 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—We hold interests in an offshore oil port, LOOP, and a crude oil pipeline system, LOCAP. Both LOOP and LOCAP have secured various project financings with throughput and deficiency agreements. Under the agreements, we are 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 vary but tend to follow the terms of the underlying debt, which extend through 2037. Our maximum potential undiscounted payments under these agreements for the debt principal totaled $172 million as of September 30, 2014.
	We hold an interest in a refined products pipeline through our investment in Centennial, and have guaranteed the payment of Centennial’s principal, interest and prepayment costs, if applicable, under a Master Shelf Agreement, which is scheduled to expire in 2024. The guarantee arose in order for Centennial to obtain adequate financing. Our maximum potential undiscounted payments under this agreement for debt principal totaled $39 million as of September 30, 2014.
	We hold an interest in an ethanol production facility through our investment in TAME, and through our participation as a lender under TAME’s revolving credit agreement, have agreed to reimburse the bank for 50 percent of any amounts drawn on a letter of credit that has been issued to secure TAME’s repayment of the tax exempt bonds. The credit agreement expires in 2018. Our maximum potential undiscounted payments under this arrangement were $25 million at September 30, 2014.
	Marathon Oil indemnifications—In conjunction with our spinoff from Marathon Oil, we have entered into arrangements with Marathon Oil providing indemnities and guarantees with recorded values of $2 million as of September 30, 2014, which consist of unrecognized tax benefits related to MPC, its consolidated subsidiaries and the refining, marketing and transportation business operations prior to our spinoff which are not already reflected in the unrecognized tax benefits described in Note 11, and other contingent liabilities Marathon Oil may incur related to taxes. Furthermore, 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 $122 million as of September 30, 2014, which primarily consist of a commitment to contribute cash to an equity method investee for certain catastrophic events, up to $50 million per event, in lieu of procuring insurance coverage, an indemnity to the co-lenders associated with an equity method investee’s credit agreement, 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—At September 30, 2014, our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $1.8 billion, which includes $520 million of contingent consideration associated with the acquisition of the Galveston Bay Refinery and Related Assets, $751 million for contributions to North Dakota Pipeline and $208 million for contributions to the SAX project. See Note 4 for additional information on our investments in North Dakota Pipeline and the SAX project. See Notes 4 and 15 for additional information on the contingent consideration.

Subsequent_Event

Subsequent Event	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Event
	On October 29, 2014, our board of directors authorized the sale of MPC's remaining 31 percent interest in Pipe Line Holdings to MPLX. Upon completion, we will account for the sale as an equity transaction and will not record a gain or loss.

Supplementary_Statistics

Supplementary Statistics	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Supplementary Statistics	'
	Supplementary Statistics (Unaudited)
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Income from Operations by segment
	Refining & Marketing	$	971		$	227		$	2,593		$	2,235
	Speedway	119			102			271			292
	Pipeline Transportation(a)	69			54			222			163
	Items not allocated to segments:
	Corporate and other unallocated items(a)	(76		)	(59		)	(204		)	(190		)
	Pension settlement expenses	(21		)	(23		)	(90		)	(83		)
	Income from operations	$	1,062		$	301		$	2,792		$	2,417
	Capital Expenditures and Investments(b)(c)
	Refining & Marketing	$	318		$	243		$	731		$	1,797
	Speedway	2,707			65			2,783			177
	Pipeline Transportation	224			42			418			173
	Corporate and Other(d)	29			61			80			121
	Total	$	3,278		$	411		$	4,012		$	2,268
	(a)	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
	(b)	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
	(c)	The three and nine months ended September 30, 2014 includes $2.68 billion for the acquisition of Hess' Retail Operations and Related Assets. The nine months ended September 30, 2013 includes $1.36 billion for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4 to the unaudited consolidated financial statements.
	(d)	Includes capitalized interest of $7 million for both the three months ended September 30, 2014 and 2013, and $20 million and $15 million for the nine months ended September 30, 2014 and 2013, respectively.
	Supplementary Statistics (Unaudited)
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)(a)(b)	2,155			2,155			2,092			2,063
	Refining & Marketing Operating Statistics(b)
	Refining & Marketing refined product sales volume (thousands of barrels per day)(c)	2,140			2,148			2,079			2,052
	Refining & Marketing gross margin (dollars per barrel)(d)	$	14.55		$	9.25		$	15.02		$	12.42
	Crude oil capacity utilization percent(e)	100			99			94			97
	Refinery throughputs (thousands of barrels per day):(f)
	Crude oil refined	1,720			1,682			1,616			1,603
	Other charge and blendstocks	160			195			172			202
	Total	1,880			1,877			1,788			1,805
	Sour crude oil throughput percent	52			53			52			53
	WTI-priced crude oil throughput percent	16			21			18			22
	Refined product yields (thousands of barrels per day):(f)
	Gasoline	864			938			851			917
	Distillates	598			578			574			570
	Propane	36			39			36			37
	Feedstocks and special products	330			259			280			227
	Heavy fuel oil	24			31			27			31
	Asphalt	63			70			52			57
	Total	1,915			1,915			1,820			1,839
	Refinery direct operating costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	1.52		$	0.96		$	1.82		$	0.94
	Depreciation and amortization	1.35			1.27			1.43			1.32
	Other manufacturing(h)	4.33			4.1			4.96			4
	Total	$	7.2		$	6.33		$	8.21		$	6.26
	Refining & Marketing Operating Statistics By Region - Gulf Coast(b)
	Refinery throughputs (thousands of barrels per day):(i)
	Crude oil refined	1,075			1,035			989			971
	Other charge and blendstocks	155			175			174			181
	Total	1,230			1,210			1,163			1,152
	Sour crude oil throughput percent	66			64			64			65
	WTI-priced crude oil throughput percent	1			7			2			8
	Refined product yields (thousands of barrels per day):(i)
	Gasoline	505			561			498			545
	Distillates	389			370			366			363
	Propane	25			24			24			23
	Feedstocks and special products	310			241			275			214
	Heavy fuel oil	8			21			13			20
Asphalt	19			23			13			14
Total	1,256			1,240			1,189			1,179
Refinery direct operating costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	1.15		$	0.86		$	1.77		$	0.77
Depreciation and amortization	1.1			1.01			1.16			1.04
Other manufacturing(h)	4.11			4.08			4.86			3.82
Total	$	6.36		$	5.95		$	7.79		$	5.63
Supplementary Statistics (Unaudited)
	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2014			2013			2014			2013
Refining & Marketing Operating Statistics By Region - Midwest
Refinery throughputs (thousands of barrels per day):(i)
Crude oil refined	645			647			627			632
Other charge and blendstocks	38			56			43			55
Total	683			703			670			687
Sour crude oil throughput percent	30			35			33			35
WTI-priced crude oil throughput percent	41			43			42			43
Refined product yields (thousands of barrels per day):(i)
Gasoline	359			377			353			373
Distillates	209			208			208			207
Propane	13			15			13			14
Feedstocks and special products	51			54			49			46
Heavy fuel oil	16			10			14			11
Asphalt	44			47			39			43
Total	692			711			676			694
Refinery direct operating costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	2.1		$	1.08		$	1.78		$	1.17
Depreciation and amortization	1.75			1.66			1.8			1.72
Other manufacturing(h)	4.51			3.91			4.82			4.1
Total	$	8.36		$	6.65		$	8.4		$	6.99
Speedway Operating Statistics
Convenience stores at period-end(j)	2,744			1,471
Gasoline and distillate sales (millions of gallons)	842			803			2,421			2,329
Gasoline and distillate gross margin (dollars per gallon)(k)	$	0.1596		$	0.1404		$	0.1351		$	0.1483
Merchandise sales (in millions)	$	870		$	843		$	2,422		$	2,360
Merchandise gross margin (in millions)	$	235		$	224		$	651		$	620
Merchandise gross margin percent	27		%	26.5		%	26.9		%	26.3		%
Same store gasoline sales volume (period over period)	(0.8		%)	1		%	(1.0		%)	0.6		%
Same store merchandise sales (period over period)(l)	4.8		%	5.6		%	4.8		%	3.8		%
Pipeline Transportation Operating Statistics
Pipeline throughputs (thousands of barrels per day):(m)
Crude oil pipelines	1,265			1,317			1,230			1,308
Refined products pipelines	839			913			843			930
Total	2,104			2,230			2,073			2,238
(a)	Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers.
(b)	Includes the impact of the Galveston Bay Refinery and Related Assets beginning on the February 1, 2013 acquisition date.
(c)	Includes intersegment sales.
(d)	Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs.
(e)	Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities.
(f)	Excludes inter-refinery volumes of 33 mbpd and 36 mbpd for the three months ended September 30, 2014 and 2013, respectively, and 45 mbpd and 34 mbpd for the nine months ended September 30, 2014 and 2013, respectively.
(g)	Per barrel of total refinery throughputs.
(h)	Includes utilities, labor, routine maintenance and other operating costs.
(i)	Includes inter-refinery transfer volumes.
(j)	Includes 1,245 stores acquired on September 30, 2014 through the acquisition of Hess' Retail Operations and Related Assets. Segment results for the period prior to the acquisition do not include results from these operations.
(k)	The price paid by consumers less the cost of refined products, including transportation, consumer excise taxes and bankcard processing fees, divided by gasoline and distillate sales volume.
(l)	Excludes cigarettes.
(m)	On owned common-carrier pipelines, excluding equity method investments.

Description_of_the_Business_an1

Description of the Business and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [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 Securities and Exchange Commission applicable to interim period financial statements and do not include all of the information and disclosures required by United States generally accepted accounting principles (“U.S. GAAP”) for complete financial statements.
Inventories	'
	Inventories are carried at the lower of cost or market value. The cost of inventories of crude oil and refinery feedstocks, refined products and merchandise is determined primarily under the last-in, first-out (“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 and (4) the acquisition of ethanol for blending with refined products.
Stock-based compensation arrangements	'
	The fair value of stock options granted to our employees is estimated on the date of the grant using the Black Scholes option-pricing model, which employs various assumptions. Beginning in the first quarter of 2014, the assumption for expected volatility of our stock price was refined to reflect a weighting of 50 percent of MPC’s common stock implied volatility and 50 percent of MPC's common stock historical volatility.

Acquisitions_and_Investments_T

Acquisitions and Investments (Tables)	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	'
	The estimated fair values of assets acquired and liabilities assumed at the acquisition date, pending the completion of an independent appraisal and other evaluations, are as follows:
	(In millions)
	Cash and cash equivalents	$	39
	Receivables	132
	Inventories	178
	Other current assets	5
	Property, plant and equipment, net	2,062
	Other noncurrent assets	103
	Total assets acquired	2,519
	Accounts payable	77
	Payroll and benefits payable	4
	Consumer excise taxes payable	80
	Other current liabilities	10
	Defined benefit postretirement plan obligations	2
	Deferred credits and other liabilities	122
	Total liabilities assumed	295
	Net assets acquired excluding goodwill	2,224
	Goodwill	600
	Net assets acquired	$	2,824
Business Acquisition, Pro Forma Information [Table Text Block]	'
	The following unaudited pro forma financial information presents consolidated results assuming the Galveston Bay Refinery and Related Assets acquisition occurred on January 1, 2012 and Hess' Retail Operations and Related Assets acquisition occurred on January 1, 2013. The pro forma financial information does not give effect to potential synergies that could result from the acquisitions and is not necessarily indicative of the results of future operations.
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions, except per share data)	2014		2013		2014		2013
	Sales and other operating revenues (including consumer excise taxes)	$	28,284	$	29,317	$	84,232	$	86,386
	Net income attributable to MPC	698		170		1,748		1,516
	Net income attributable to MPC per share - basic	$	2.48	$	0.55	$	6.07	$	4.72
	Net income attributable to MPC per share - diluted	2.46		0.55		6.03		4.69

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2014
Related Party Transactions [Abstract]	'
Sales To Related Parties	'
	Sales to related parties, which are included in sales and other operating revenues (including consumer excise taxes) on the consolidated statements of income, were as follows:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions)	2014		2013		2014		2013
	Other equity method investees	$	2	$	3	$	6	$	7
Purchases From Related Parties	'
	Purchases from related parties were as follows:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions)	2014		2013		2014		2013
	Centennial	$	—	$	4	$	7	$	4
	Explorer	10		—		32		—
	LOCAP	6		5		16		13
	LOOP	12		11		77		32
	TAAE	19		8		61		8
	TACE	33		42		90		92
	TAME	29		31		111		98
	Other equity method investees	3		2		7		7
	Total	$	112	$	103	$	401	$	254
Receivables From Related Parties	'
	Receivables from related parties, which are included in receivables, less allowance for doubtful accounts on the consolidated balance sheets, were as follows:
	(In millions)	September 30,		December 31,
		2014		2013
	Centennial	$	2	$	1
	TAME	2		1
	Total	$	4	$	2
Payables To Related Parties	'
	Payables to related parties, which are included in accounts payable on the consolidated balance sheets, were as follows:
	(In millions)	September 30,		December 31,
		2014		2013
	Explorer	$	5	$	—
	LOCAP	2		2
	LOOP	4		3
	TAAE	1		2
	TACE	2		4
	TAME	2		5
	Other equity method investees	1		—
	Total	$	17	$	16

Income_per_Common_Share_Tables

Income per Common Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Summary of Earnings Per Common Share	'
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions, except per share data)	2014			2013			2014		2013
	Basic earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	672		$	168		$	1,726	$	1,486
	Income allocated to participating securities	1			—			3		2
	Income available to common stockholders - basic	$	671		$	168		$	1,723	$	1,484
	Weighted average common shares outstanding	282			309			288		321
	Basic earnings per share	$	2.38		$	0.54		$	5.99	$	4.63
	Diluted earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	672		$	168		$	1,726	$	1,486
	Income allocated to participating securities	1			—			3		2
	Income available to common stockholders - diluted	$	671		$	168		$	1,723	$	1,484
	Weighted average common shares outstanding	282			309			288		321
	Effect of dilutive securities	2			2			2		2
	Weighted average common shares, including dilutive effect	284			311			290		323
	Diluted earnings per share	$	2.36		$	0.54		$	5.95	$	4.6
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					Nine Months Ended
		September 30,					September 30,
	(In millions)	2014		2013			2014		2013
	Shares issued under stock-based compensation plans	—		1			—		1

Equity_Tables

Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Share Repurchases Transacted Through ASR Programs and Open Market Transactions	'
	Total share repurchases were as follows for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
	(In millions, except per share data)	2014		2013		2014		2013
	Number of shares repurchased(a)	4		14		17		31
	Cash paid for shares repurchased	$	301	$	1,028	$	1,449	$	2,341
	Effective average cost per delivered share	$	85.15	$	70.73	$	87.25	$	76.01
	(a)	The nine months ended September 30, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in 2012.

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Income From Operations Attributable To Operating Segments	'
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Three Months Ended September 30, 2014
	Revenues:
	Customer	$	21,568		$	3,854		$	16		$	25,438
	Intersegment(a)	2,400			2			136			2,538
	Segment revenues	$	23,968		$	3,856		$	152		$	27,976
	Segment income from operations(b)	$	971		$	119		$	69		$	1,159
	Income from equity method investments	17			—			12			29
	Depreciation and amortization(c)	257			33			20			310
	Capital expenditures and investments(d)(f)	318			2,707			224			3,249
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Three Months Ended September 30, 2013
	Revenues:
	Customer	$	22,481		$	3,755		$	20		$	26,256
	Intersegment(a)	2,439			1			117			2,557
	Segment revenues	$	24,920		$	3,756		$	137		$	28,813
	Segment income from operations(b)	$	227		$	102		$	54		$	383
	Income from equity method investments	8			—			1			9
	Depreciation and amortization(c)	246			29			19			294
	Capital expenditures and investments(d)	243			65			42			350
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Nine Months Ended September 30, 2014
	Revenues:
	Customer	$	64,295		$	11,220		$	52		$	75,567
	Intersegment(a)	7,223			4			396			7,623
	Segment revenues	$	71,518		$	11,224		$	448		$	83,190
	Segment income from operations(b)	$	2,593		$	271		$	222		$	3,086
	Income from equity method investments	76			—			45			121
	Depreciation and amortization(c)	782			90			58			930
	Capital expenditures and investments(d)(f)	731			2,783			418			3,932
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Nine Months Ended September 30, 2013
	Revenues:
	Customer	$	64,245		$	10,964		$	60		$	75,269
	Intersegment(a)	7,072			3			340			7,415
	Segment revenues	$	71,317		$	10,967		$	400		$	82,684
	Segment income from operations(b)	$	2,235		$	292		$	163		$	2,690
	Income from equity method investments	7			—			9			16
	Depreciation and amortization(c)	734			83			55			872
	Capital expenditures and investments(d)(e)	1,797			177			173			2,147
	(a)	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.
	(b)	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
	(c)	Differences between segment totals and MPC totals represent amounts related to unallocated items and are included in “Items not allocated to segments” in the reconciliation below.
	(d)	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
	(e)	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4.
	(f)	The Speedway and Refining & Marketing segments include $2.63 billion and $54 million, respectively, for the acquisition of Hess' Retail Operations and Related Assets. See Note 4.
Reconciliation Of Segment Income From Operations To Income Before Income Taxes	'
	The following reconciles segment income from operations to income before income taxes as reported in the consolidated statements of income:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Segment income from operations	$	1,159		$	383		$	3,086		$	2,690
	Items not allocated to segments:
	Corporate and other unallocated items(a)(b)	(76		)	(59		)	(204		)	(190		)
	Pension settlement expenses(c)	(21		)	(23		)	(90		)	(83		)
	Net interest and other financial income (costs)	(50		)	(47		)	(144		)	(140		)
	Income before income taxes	$	1,012		$	254		$	2,648		$	2,277
	(a)	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets.
	(b)	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
	(c)	See Note 20.
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						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Segment capital expenditures and investments	$	3,249		$	350		$	3,932		$	2,147
	Less: Investments in equity method investees	177			75			341			86
	Plus: Items not allocated to segments:
	Capital expenditures not allocated to segments	22			54			60			106
	Capitalized interest	7			7			20			15
	Total capital expenditures(a)(b)	$	3,101		$	336		$	3,671		$	2,182
	(a)	Capital expenditures include changes in capital accruals and acquisitions.
	(b)	See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
Reconciliation Of Total Revenues To Sales And Other Operating Revenues	'
	The following reconciles customer revenues to sales and other operating revenues (including consumer excise taxes) as reported in the consolidated statements of income:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Customer revenues (as reported above)	$	25,438		$	26,256		$	75,567		$	75,269
	Corporate and other unallocated items	—			—			—			(6		)
	Sales and other operating revenues (including consumer excise taxes)	$	25,438		$	26,256		$	75,567		$	75,263
Total Assets By Reportable Segment	'
	Total assets by reportable segment were:
	(In millions)	September 30,			December 31, 2013
		2014
	Refining & Marketing	$	20,207		$	19,573
	Speedway	5,203			2,064
	Pipeline Transportation	2,329			1,947
	Corporate and Other	3,966			4,801
	Total consolidated assets	$	31,705		$	28,385

Other_Items_Tables

Other Items (Tables)	9 Months Ended
	Sep. 30, 2014
Other Income and Expenses [Abstract]	'
Net Interest And Other Financial Income (Costs)	'
	Net interest and other financial income (costs) was:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Interest:
	Interest income	$	2		$	2		$	5		$	7
	Interest expense	(56		)	(50		)	(154		)	(147		)
	Interest capitalized	7			7			20			15
	Total net interest	(47		)	(41		)	(129		)	(125		)
	Other:
	Net foreign currency gains (losses)	1			(1		)	—			—
	Bank service and other fees	(4		)	(5		)	(15		)	(15		)
	Total other	(3		)	(6		)	(15		)	(15		)
	Net interest and other financial income (costs)	$	(50	)	$	(47	)	$	(144	)	$	(140	)

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Summary Of Inventories	'
	(In millions)	September 30,		December 31,
		2014		2013
	Crude oil and refinery feedstocks	$	2,405	$	1,797
	Refined products	2,731		2,367
	Materials and supplies	308		425
	Merchandise	164		100
	Total (at cost)	$	5,608	$	4,689

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2014
Property, Plant and Equipment [Abstract]	'
Summary Of Property, Plant And Equipment	'
	(In millions)	September 30,		December 31,
		2014		2013
	Refining & Marketing	$	17,646	$	16,982
	Speedway	4,477		2,344
	Pipeline Transportation	1,995		1,921
	Corporate and Other	594		546
	Total	24,712		21,793
	Less accumulated depreciation	8,713		7,872
	Property, plant and equipment, net	$	15,999	$	13,921

Goodwill_Tables

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of Goodwill	'
	The changes in the carrying amount of goodwill for nine months ended September 30, 2014 were as follows:
	(In millions)	Refining & Marketing			Speedway		Pipeline Transportation		Total
	Balance as of December 31, 2013	$	551		$	225	$	162	$	938
	Acquisition(a)	—			600		—		600
	Disposition	(1		)	—		—		(1		)
	Balance as of September 30, 2014	$	550		$	825	$	162	$	1,537
	(a)	See Note 4 for information on the acquisitions.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013 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.
		September 30, 2014
		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
	Commodity derivative instruments, assets	$	87		$	—		$	—		$	(55	)	$	32	$	60
	Other assets	2			—			—			N/A			2		—
	Total assets at fair value	$	89		$	—		$	—		$	(55	)	$	34	$	60
	Commodity derivative instruments, liabilities	$	55		$	—		$	—		$	(55	)	$	—	$	—
	Contingent consideration, liability(c)	—			—			475			N/A			475		—
	Total liabilities at fair value	$	55		$	—		$	475		$	(55	)	$	475	$	—
		December 31, 2013
		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
	Commodity derivative instruments, assets	$	21		$	—		$	—		$	(21	)	$	—	$	61
	Other assets	2			—			—			N/A			2		—
	Total assets at fair value	$	23		$	—		$	—		$	(21	)	$	2	$	61
	Commodity derivative instruments, liabilities	$	53		$	—		$	—		$	(53	)	$	—	$	—
	Contingent consideration, liability(c)	—			—			625			N/A			625		—
	Total liabilities at fair value	$	53		$	—		$	625		$	(53	)	$	625	$	—
	(a)	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of September 30, 2014 and December 31, 2013, cash collateral of $0 million and $32 million, respectively, was netted with mark-to-market derivative liabilities.
	(b)	We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.
	(c)	Includes $193 million and $159 million classified as current at September 30, 2014 and December 31, 2013, respectively.
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 liabilities classified as Level 3 in the fair value hierarchy.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Beginning balance	$	647		$	611		$	625		$	—
	Contingent consideration agreement	—			—			—			600
	Contingent consideration payment	(180		)	—			(180		)	—
	Unrealized (gains) losses included in net income	8			(5		)	30			6
	Ending balance	$	475		$	606		$	475		$	606
Fair Value Measurements, Nonrecurring	'
		Nine Months Ended September 30,
		2014						2013
	(In millions)	Fair Value			Impairment			Fair Value			Impairment
	Property, plant and equipment, net	$	—		$	—		$	1		$	8
	Other noncurrent assets	—			11			—			—
Financial Instruments at Fair Value, Excluding Derivative Financial Instruments and Contingent Consideration	'
	The following table summarizes financial instruments on the basis of their nature, characteristics and risk at September 30, 2014 and December 31, 2013, excluding the derivative financial instruments and contingent consideration reported above.
		September 30, 2014						December 31, 2013
	(In millions)	Fair Value			Carrying Value			Fair Value			Carrying Value
	Financial assets:
	Investments	$	23		$	2		$	336		$	14
	Other	31			29			31			30
	Total financial assets	$	54		$	31		$	367		$	44
	Financial liabilities:
	Long-term debt(a)	$	6,224		$	5,886		$	3,306		$	3,001
	Deferred credits and other liabilities	20			20			21			21
	Total financial liabilities	$	6,244		$	5,906		$	3,327		$	3,022
	(a)	Excludes capital leases

Derivatives_Tables

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Classification of Fair Values of Derivative Instruments, Excluding Cash Collateral	'
	The following table presents the gross fair values of derivative instruments, excluding cash collateral, and where they appear on the consolidated balance sheets as of September 30, 2014 and December 31, 2013:
		September 30, 2014
	(In millions)	Asset				Liability			Balance Sheet Location
	Commodity derivatives	$	87			$	55		Other current assets
		December 31, 2013
	(In millions)	Asset				Liability			Balance Sheet Location
	Commodity derivatives	$	21			$	53		Other current assets
Open Commodity Derivative Contracts	'
	The table below summarizes open commodity derivative contracts as of September 30, 2014.
		Position		Total Barrels (In thousands)
	Crude oil(a)
	Exchange-traded	Long		10,346
	Exchange-traded	Short		(23,186	)
	Refined Products(b)
	Exchange-traded	Long		1,695
	Exchange-traded	Short		(3,281	)
	(a)	96 percent of these contracts expire in the fourth quarter of 2014.
	(b)	100 percent of these contracts expire in the fourth quarter of 2014.
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)							Gain (Loss)
	(In millions)	Three Months Ended September 30,							Nine Months Ended September 30,
	Income Statement Location	2014				2013			2014			2013
	Sales and other operating revenues	$	10			$	9		$	18		$	13
	Cost of revenues	145				(170		)	(30		)	(179		)
	Total	$	155			$	(161	)	$	(12	)	$	(166	)

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Outstanding Borrowings	'
	Our outstanding borrowings at September 30, 2014 and December 31, 2013 consisted of the following:
	(In millions)	September 30,			December 31,
		2014			2013
	Marathon Petroleum Corporation:
	Revolving credit agreement due 2017	$	—		$	—
	Term loan agreement due 2019	700			—
	3.500% senior notes due March 1, 2016	750			750
	5.125% senior notes due March 1, 2021	1,000			1,000
	3.625% senior notes due September 15, 2024	750			—
	6.500% senior notes due March 1, 2041	1,250			1,250
	4.750% senior notes due September 15, 2044	800			—
	5.000% senior notes due September 15, 2054	400			—
	Consolidated subsidiaries:
	Capital lease obligations due 2014-2028	378			395
	MPLX Operations LLC revolving credit agreement due 2017	255			—
	Trade receivables securitization facility due 2016	—			—
	Total	6,283			3,395
	Unamortized discount	(26		)	(10		)
	Fair value adjustments(a)	7			11
	Amounts due within one year	(26		)	(23		)
	Total long-term debt due after one year	$	6,238		$	3,373
	(a)	The $20 million gain on the termination of our interest rate swap agreements in 2012 is being amortized over the remaining life of the 3.50 percent senior notes.

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2014
Supplemental Cash Flow Elements [Abstract]	'
Summary of Supplemental Cash Flow Information	'
		Nine Months Ended
		September 30,
	(In millions)	2014		2013
	Net cash provided by operating activities included:
	Interest paid (net of amounts capitalized)	$	162	$	166
	Net income taxes paid to taxing authorities	969		1,027
	Non-cash investing and financing activities:
	Capital lease obligations increase	$	—	$	61
	Property, plant and equipment sold	4		43
	Property, plant and equipment acquired	4		—
	Acquisition:
	Contingent consideration(a)	—		600
	Payable to seller(a)	—		6
	(a)	Acquisition-date fair value of non-cash consideration associated with the Galveston Bay Refinery and Related Assets acquisition.
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:
		Nine Months Ended
		September 30,
	(In millions)	2014		2013
	Additions to property, plant and equipment per consolidated statements of cash flows	$	952	$	733
	Non-cash additions to property, plant and equipment	4		—
	Acquisitions(a)	2,714		1,386
	Asset retirement expenditures	1		—
	Increase in capital accruals	—		63
	Total capital expenditures	$	3,671	$	2,182
	(a)	The 2014 acquisition includes the acquisition of Hess' Retail Operations and Related Assets. The 2013 acquisition includes the acquisition of the Galveston Bay Refinery and Related Assets. The acquisition numbers above include property, plant and equipment and intangibles. See Note 4.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2014
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, 2012	$	(432	)	$	(36	)	$	4	$	—		$	(464	)
	Other comprehensive income before reclassifications	172			3			—		2			177
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(34		)	(3		)	—		—			(37		)
	– actuarial loss(a)	53			2			—		—			55
	– settlement loss(a)	83			—			—		—			83
	Tax effect	(19		)	—			—		—			(19		)
	Other comprehensive income	255			2			—		2			259
	Balance as of September 30, 2013	$	(177	)	$	(34	)	$	4	$	2		$	(205	)
	(In millions)	Pension Benefits			Other Benefits			Gain on Cash Flow Hedge		Workers Compensation			Total
	Balance as of December 31, 2013	$	(161	)	$	(50	)	$	4	$	3		$	(204	)
	Other comprehensive income (loss) before reclassifications	(88		)	8			—		(2		)	(82		)
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(35		)	(3		)	—		—			(38		)
	– actuarial loss(a)	38			2			—		—			40
	– settlement loss(a)	90			—			—		—			90
	Tax effect	(35		)	1			—		—			(34		)
	Other comprehensive income (loss)	(30		)	8			—		(2		)	(24		)
	Balance as of September 30, 2014	$	(191	)	$	(42	)	$	4	$	1		$	(228	)
	(a)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 20.

Defined_Benefit_Pension_and_Ot1

Defined Benefit Pension and Other Postretirement Plans (Tables)	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Components of Net Periodic Benefit Costs	'
	The following summarizes the components of net periodic benefit costs:
		Three Months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	24		$	24		$	7		$	7
	Interest cost	18			19			7			6
	Expected return on plan assets	(27		)	(28		)	—			—
	Amortization – prior service credit	(12		)	(12		)	(1		)	(1		)
	– actuarial loss	12			14			1			1
	– settlement loss	21			23			—			—
	Net periodic benefit cost	$	36		$	40		$	14		$	13
		Nine Months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	67		$	70		$	20		$	19
	Interest cost	56			55			24			19
	Expected return on plan assets	(81		)	(81		)	—			—
	Amortization – prior service credit	(35		)	(34		)	(3		)	(3		)
	– actuarial loss	38			53			2			2
	– settlement loss	90			83			—			—
	Net periodic benefit cost	$	135		$	146		$	43		$	37

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Summary of Stock Option Award Activity	'
	The following table presents a summary of our stock option award activity for the nine months ended September 30, 2014:
		Number of Shares(a)		Weighted Average Exercise Price
	Outstanding at December 31, 2013	5,147,837		$	40.08
	Granted	446,310		85.02
	Exercised	(696,159	)	32.12
	Forfeited, canceled or expired	(20,761	)	49.67
	Outstanding at September 30, 2014	4,877,227		45.28
	(a)	Includes an immaterial number of stock appreciation rights.
Summary of Restricted Stock Award Activity	'
	The following table presents a summary of restricted stock award activity for the nine months ended September 30, 2014:
		Shares of Restricted Stock ("RS")				Restricted Stock Units ("RSU")
		Number of Shares		Weighted Average Grant Date Fair Value		Number of Units		Weighted Average Grant Date Fair Value
	Outstanding at December 31, 2013	624,122		$	61.11	385,079		$	33.96
	Granted	240,882		87.81		19,827		86.79
	RS's Vested/RSU's Issued	(324,697	)	55.47		(398	)	60.11
	Forfeited	(25,943	)	70.1		(133	)	76.1
	Outstanding at September 30, 2014	514,364		76.73		404,375		36.51
Schedule of Performance Unit Awards	'
	The following table presents a summary of the activity for performance unit awards to be settled in shares for the nine months ended September 30, 2014:
		Number of Units
	Outstanding at December 31, 2013	3,822,500
	Granted	2,033,700
	Settled	—
	Canceled	—
	Outstanding at September 30, 2014	5,856,200

Supplementary_Statistics_Table

Supplementary Statistics (Tables)	9 Months Ended
	Sep. 30, 2014
Text Block [Abstract]	'
Supplementary Statistics	'
	Supplementary Statistics (Unaudited)
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	(In millions)	2014			2013			2014			2013
	Income from Operations by segment
	Refining & Marketing	$	971		$	227		$	2,593		$	2,235
	Speedway	119			102			271			292
	Pipeline Transportation(a)	69			54			222			163
	Items not allocated to segments:
	Corporate and other unallocated items(a)	(76		)	(59		)	(204		)	(190		)
	Pension settlement expenses	(21		)	(23		)	(90		)	(83		)
	Income from operations	$	1,062		$	301		$	2,792		$	2,417
	Capital Expenditures and Investments(b)(c)
	Refining & Marketing	$	318		$	243		$	731		$	1,797
	Speedway	2,707			65			2,783			177
	Pipeline Transportation	224			42			418			173
	Corporate and Other(d)	29			61			80			121
	Total	$	3,278		$	411		$	4,012		$	2,268
	(a)	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
	(b)	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
	(c)	The three and nine months ended September 30, 2014 includes $2.68 billion for the acquisition of Hess' Retail Operations and Related Assets. The nine months ended September 30, 2013 includes $1.36 billion for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4 to the unaudited consolidated financial statements.
	(d)	Includes capitalized interest of $7 million for both the three months ended September 30, 2014 and 2013, and $20 million and $15 million for the nine months ended September 30, 2014 and 2013, respectively.
Operating Statistics	'
	Supplementary Statistics (Unaudited)
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)(a)(b)	2,155			2,155			2,092			2,063
	Refining & Marketing Operating Statistics(b)
	Refining & Marketing refined product sales volume (thousands of barrels per day)(c)	2,140			2,148			2,079			2,052
	Refining & Marketing gross margin (dollars per barrel)(d)	$	14.55		$	9.25		$	15.02		$	12.42
	Crude oil capacity utilization percent(e)	100			99			94			97
	Refinery throughputs (thousands of barrels per day):(f)
	Crude oil refined	1,720			1,682			1,616			1,603
	Other charge and blendstocks	160			195			172			202
	Total	1,880			1,877			1,788			1,805
	Sour crude oil throughput percent	52			53			52			53
	WTI-priced crude oil throughput percent	16			21			18			22
	Refined product yields (thousands of barrels per day):(f)
	Gasoline	864			938			851			917
	Distillates	598			578			574			570
	Propane	36			39			36			37
	Feedstocks and special products	330			259			280			227
	Heavy fuel oil	24			31			27			31
	Asphalt	63			70			52			57
	Total	1,915			1,915			1,820			1,839
	Refinery direct operating costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	1.52		$	0.96		$	1.82		$	0.94
	Depreciation and amortization	1.35			1.27			1.43			1.32
	Other manufacturing(h)	4.33			4.1			4.96			4
	Total	$	7.2		$	6.33		$	8.21		$	6.26
	Refining & Marketing Operating Statistics By Region - Gulf Coast(b)
	Refinery throughputs (thousands of barrels per day):(i)
	Crude oil refined	1,075			1,035			989			971
	Other charge and blendstocks	155			175			174			181
	Total	1,230			1,210			1,163			1,152
	Sour crude oil throughput percent	66			64			64			65
	WTI-priced crude oil throughput percent	1			7			2			8
	Refined product yields (thousands of barrels per day):(i)
	Gasoline	505			561			498			545
	Distillates	389			370			366			363
	Propane	25			24			24			23
	Feedstocks and special products	310			241			275			214
	Heavy fuel oil	8			21			13			20
	Asphalt	19			23			13			14
	Total	1,256			1,240			1,189			1,179
	Refinery direct operating costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	1.15		$	0.86		$	1.77		$	0.77
	Depreciation and amortization	1.1			1.01			1.16			1.04
	Other manufacturing(h)	4.11			4.08			4.86			3.82
	Total	$	6.36		$	5.95		$	7.79		$	5.63
	Supplementary Statistics (Unaudited)
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Refining & Marketing Operating Statistics By Region - Midwest
	Refinery throughputs (thousands of barrels per day):(i)
	Crude oil refined	645			647			627			632
	Other charge and blendstocks	38			56			43			55
	Total	683			703			670			687
	Sour crude oil throughput percent	30			35			33			35
	WTI-priced crude oil throughput percent	41			43			42			43
	Refined product yields (thousands of barrels per day):(i)
	Gasoline	359			377			353			373
	Distillates	209			208			208			207
	Propane	13			15			13			14
Feedstocks and special products	51			54			49			46
Heavy fuel oil	16			10			14			11
Asphalt	44			47			39			43
Total	692			711			676			694
Refinery direct operating costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	2.1		$	1.08		$	1.78		$	1.17
Depreciation and amortization	1.75			1.66			1.8			1.72
Other manufacturing(h)	4.51			3.91			4.82			4.1
Total	$	8.36		$	6.65		$	8.4		$	6.99
Speedway Operating Statistics
Convenience stores at period-end(j)	2,744			1,471
Gasoline and distillate sales (millions of gallons)	842			803			2,421			2,329
Gasoline and distillate gross margin (dollars per gallon)(k)	$	0.1596		$	0.1404		$	0.1351		$	0.1483
Merchandise sales (in millions)	$	870		$	843		$	2,422		$	2,360
Merchandise gross margin (in millions)	$	235		$	224		$	651		$	620
Merchandise gross margin percent	27		%	26.5		%	26.9		%	26.3		%
Same store gasoline sales volume (period over period)	(0.8		%)	1		%	(1.0		%)	0.6		%
Same store merchandise sales (period over period)(l)	4.8		%	5.6		%	4.8		%	3.8		%
Pipeline Transportation Operating Statistics
Pipeline throughputs (thousands of barrels per day):(m)
Crude oil pipelines	1,265			1,317			1,230			1,308
Refined products pipelines	839			913			843			930
Total	2,104			2,230			2,073			2,238
(a)	Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers.
(b)	Includes the impact of the Galveston Bay Refinery and Related Assets beginning on the February 1, 2013 acquisition date.
(c)	Includes intersegment sales.
(d)	Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs.
(e)	Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities.
(f)	Excludes inter-refinery volumes of 33 mbpd and 36 mbpd for the three months ended September 30, 2014 and 2013, respectively, and 45 mbpd and 34 mbpd for the nine months ended September 30, 2014 and 2013, respectively.
(g)	Per barrel of total refinery throughputs.
(h)	Includes utilities, labor, routine maintenance and other operating costs.
(i)	Includes inter-refinery transfer volumes.
(j)	Includes 1,245 stores acquired on September 30, 2014 through the acquisition of Hess' Retail Operations and Related Assets. Segment results for the period prior to the acquisition do not include results from these operations.
(k)	The price paid by consumers less the cost of refined products, including transportation, consumer excise taxes and bankcard processing fees, divided by gasoline and distillate sales volume.
(l)	Excludes cigarettes.
(m)	On owned common-carrier pipelines, excluding equity method investments.

Description_of_the_Business_an2

Description of the Business and Basis of Presentation Basis of Presentation (Details) (Total costs and expenses, Increase in prior year bonus expense, USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Total costs and expenses | Increase in prior year bonus expense	'
Quantifying Misstatement in Current Year Financial Statements [Line Items]	'
Quantifying misstatement in current year financial statements, amount	$29

MPLX_LP_Detail

MPLX LP (Detail) (USD $)	0 Months Ended					0 Months Ended			6 Months Ended
In Millions, unless otherwise specified	Mar. 01, 2014	1-May-13	Mar. 01, 2014	Mar. 01, 2014	Oct. 31, 2012	Mar. 01, 2014	Sep. 30, 2014	Sep. 30, 2014	Apr. 30, 2013
	MPLX Pipe Line Holdings LP	MPLX Pipe Line Holdings LP	MPLX LP	MPLX LP	MPLX LP	MPLX LP	MPLX LP	MPLX LP	MPLX LP
			MPLX Revolver	Cash and cash equivalents	Butane Cavern	MPLX Pipe Line Holdings LP	General Partner and Limited Partner	General Partner	General Partner
									MPLX Pipe Line Holdings LP
Noncontrolling Interest [Line Items]	'	'	'	'	'	'	'	'	'
MPC's partnership interest in MPLX (in percentage)	'	'	'	'	'	'	73.60%	2.00%	'
Ownership interest (in percentage)	'	'	'	'	'	69.00%	'	'	51.00%
MPLX's partnership percent indirect interest in assets	'	'	'	'	100.00%	'	'	'	'
Additional interest sold	13.00%	5.00%	'	'	'	'	'	'	'
Proceeds from sale of ownership interest	$310	$100	'	'	'	'	'	'	'
Cash paid for acquisition	'	'	$270	$40	'	'	'	'	'

Acquisitions_and_Investments_A

Acquisitions and Investments (Acquisition of Hess' Retail Operations and Related Assets) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
In Millions, unless otherwise specified			Speedway	Speedway	Speedway	Hess' Retail Operations and Related Assets	Hess' Retail Operations and Related Assets	Hess' Retail Operations and Related Assets	Hess' Retail Operations and Related Assets	Hess' Retail Operations and Related Assets	Hess' Retail Operations and Related Assets
				Store			BPD	Trade Names	Lease Agreements	Above Market Leases	Speedway
											Store
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Allocation of space on Colonial Pipeline (in barrels per day)	'	'	'	'	'	'	40,000	'	'	'	'
Cash paid for acquisition	'	'	'	'	'	$2,820	'	'	'	'	'
Goodwill	1,537	938	825	'	225	'	600	'	'	'	'
Reason for business combination	'	'	'	'	'	'	'This acquisition significantly expands our Speedway presence from nine to 22 states throughout the East Coast and Southeast and is aligned with our strategy to grow higher-valued, stable cash flow businesses. This acquisition also enables us to further leverage our integrated refining and transportation operations, providing an outlet for an incremental 200,000 barrels per day of assured sales from our refining system.	'	'	'	'
Number of states in which entity operates	'	'	'	9	'	'	'	'	'	'	22
Finite-lived intangibles	'	'	'	'	'	'	'	22	'	'	'
Other noncurrent assets	'	'	'	'	'	'	103	'	60	'	'
Deferred credits and other liabilities	'	'	'	'	'	'	122	'	'	80	'
Finite-lived intangible asset, useful life	'	'	'	'	'	'	'	'2 years	'	'	'
Acquisition-related costs	'	'	'	'	'	'	$12	'	'	'	'

Acquisitions_and_Investments_S

Acquisitions and Investments (Schedule of Assets Acquired and Liabilities Assumed - Hess Retail) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Business Acquisition [Line Items]	'	'
Goodwill	$1,537	$938
Hess' Retail Operations and Related Assets	'	'
Business Acquisition [Line Items]	'	'
Cash and cash equivalents	39	'
Receivables	132	'
Inventories	178	'
Other current assets	5	'
Property, plant and equipment, net	2,062	'
Other noncurrent assets	103	'
Total assets acquired	2,519	'
Accounts payable	77	'
Payroll and benefits payable	4	'
Consumer excise taxes payable	80	'
Other current liabilities	10	'
Defined benefit postretirement plan obligations	2	'
Deferred credits and other liabilities	122	'
Total liabilities assumed	295	'
Net assets acquired excluding goodwill	2,224	'
Goodwill	600	'
Net assets acquired	$2,824	'

Acquisitions_and_Investments_A1

Acquisitions and Investments (Acquisition of Refinery and Related Logistics and Marketing Assets) (Detail) (USD $)	9 Months Ended		1 Months Ended	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Feb. 01, 2013	Sep. 30, 2014
			Galveston Bay Refinery and Related Assets	Galveston Bay Refinery and Related Assets
			site
			Pipeline
			Terminal
			BPCD
			MW
			BPD
Business Acquisition [Line Items]	'	'	'	'
Refinery capacity (in barrels per calendar day)	'	'	451,000	'
Intrastate natural gas liquid pipelines (in number of pipelines)	'	'	3	'
Number of light product terminals (in number of terminals)	'	'	4	'
Number of branded sites (in number of sites)	'	'	1,200	'
Electric cogeneration capacity, megawatt	'	'	1,040	'
Allocation of space on Colonial Pipeline (in barrels per day)	'	'	50,000	'
Cash paid for acquisition	'	'	$1,490,000,000	$180,000,000
Inventories	'	'	935,000,000	'
Total cumulative payment capped over six-year period	'	'	700,000,000	'
Term of payment of maximum earnout provision payable to the company, years	'	'	'6 years	'
Contingent consideration payment	$172,000,000	$0	'	'

Acquisitions_and_Investments_S1

Acquisitions and Investments (Schedule of Acquisition Related Pro Forma Financial Information) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Business Combinations [Abstract]	'	'	'	'
Sales and other operating revenues (including consumer excise taxes)	$28,284	$29,317	$84,232	$86,386
Net income attributable to MPC	$698	$170	$1,748	$1,516
Net income attributable to MPC per share - basic	$2.48	$0.55	$6.07	$4.72
Net income attributable to MPC per share - diluted	$2.46	$0.55	$6.03	$4.69

Acquisitions_and_Investments_A2

Acquisitions and Investments (Acquisitions of Convenience Stores) (Details) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
			Store
Business Acquisition [Line Items]	'		'
Goodwill acquired during period	$600		'
Speedway	'		'
Business Acquisition [Line Items]	'		'
Number of convenience stores acquired	'		9
Goodwill acquired during period	$600	[1]	$8
[1]	See Note 4 for information on the acquisitions.

Acquisitions_and_Investments_A3

Acquisitions and Investments (Acquisition of Biodiesel Facility) (Details) (Felda Iffco Sdn Bhd [Member], USD $)	1 Months Ended
In Millions, unless otherwise specified	Apr. 30, 2014	Apr. 01, 2014
		gallons_per_year
Felda Iffco Sdn Bhd [Member]	'	'
Business Acquisition [Line Items]	'	'
Cash paid for acquisition	$40	'
Plant capacity volume	'	60,000,000

Acquisitions_and_Investments_I

Acquisitions and Investments (Investments in Ethanol Companies) (Details) (USD $)	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Oct. 01, 2013	Aug. 01, 2013	Aug. 01, 2013	Aug. 01, 2013	Aug. 01, 2013
In Millions, unless otherwise specified	TACE	TAME	TAME	TAAE	TAAE	Ethanol Interests From Mitsui	Ethanol Interests From Mitsui	Ethanol Interests From Mitsui	Ethanol Interests From Mitsui
			TAEI			Company	TACE	TAEI	TAAE
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'	'	'	'
Number of businesses in which ownership interests acquired	'	'	'	'	'	3	'	'	'
Cash paid to acquire equity method investments	'	'	'	'	'	$75	'	'	'
Ownership percentage acquired	'	'	'	'	'	'	24.00%	34.00%	40.00%
Equity method investments, ownership percentage	60.00%	67.00%	50.00%	43.00%	43.00%	'	'	'	'

Acquisitions_and_Investments_I1

Acquisitions and Investments (Investments in Pipeline Companies) (Details) (USD $)	9 Months Ended		0 Months Ended		9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Jul. 01, 2014	Mar. 04, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Jan. 02, 2016	Jan. 02, 2016
	Illinois Extension Pipeline Company LLC	Illinois Extension Pipeline Company LLC	Explorer Pipeline	Explorer Pipeline	North Dakota Pipeline	North Dakota Pipeline	North Dakota Pipeline Class A Units	North Dakota Pipeline Class A Units
							Scenario, Forecast	Scenario, Forecast
								Maximum
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'	'	'
Equity method investments, ownership percentage	'	35.00%	'	25.00%	37.50%	37.50%	27.00%	30.00%
Cash paid to acquire equity method investments	$97	'	$77	'	$149	$173	'	'
Ownership percentage acquired	'	'	7.00%	'	'	'	'	'

Variable_Interest_Entity_Detai

Variable Interest Entity (Details) (Illinois Extension Pipeline Company LLC, Variable Interest Entity, Not Primary Beneficiary, USD $)	Sep. 30, 2014
In Millions, unless otherwise specified
Illinois Extension Pipeline Company LLC | Variable Interest Entity, Not Primary Beneficiary	'
Variable Interest Entity [Line Items]	'
VIE, maximum loss exposure, amount	$97

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Oct. 01, 2013

Sep. 30, 2014

Sep. 30, 2014

Centennial

Centennial

Centennial

Centennial

Centennial

Explorer

LOCAP

LOOP

TAAE

TAAE

TACE

TAME

Related Party Transaction [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Equity method investments, ownership percentage

50.00%

'

50.00%

'

'

25.00%

59.00%

51.00%

43.00%

43.00%

60.00%

67.00%

Operating pipeline revenue from related parties included in other income, Centennial

$0

$0

$1

$1

'

'

'

'

'

'

'

'

Long-term receivable from related party

$1

'

$1

'

$2

'

'

'

'

'

'

'

Related_Party_Transactions_Sal

Related Party Transactions - Sales to Related Parties (Detail) (Other equity method investees, USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other equity method investees	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Sales to related parties	$2	$3	$6	$7

Related_Party_Transactions_Pur

Related Party Transactions - Purchases from Related Parties (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	$112	$103	$401	$254
Centennial	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	0	4	7	4
Explorer	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	10	0	32	0
LOCAP	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	6	5	16	13
LOOP	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	12	11	77	32
TAAE	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	19	8	61	8
TACE	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	33	42	90	92
TAME	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	29	31	111	98
Other equity method investees	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'
Purchases from related parties	$3	$2	$7	$7

Related_Party_Transactions_Rec

Related Party Transactions - Receivables From Related Parties (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	$4	$2
Centennial	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	2	1
TAME	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	$2	$1

Related_Party_Transactions_Pay

Related Party Transactions - Payables To Related Parties (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Payables to related parties	$17	$16
Explorer	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	5	0
LOCAP	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	2	2
LOOP	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	4	3
TAAE	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	1	2
TACE	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	2	4
TAME	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	2	5
Other equity method investees	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	$1	$0

Income_Per_Common_Share_Summar

Income Per Common Share - Summary of Earnings Per Common Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic earnings per share:	'	'	'	'
Net income attributable to MPC	$672	$168	$1,726	$1,486
Income allocated to participating securities, basic	1	0	3	2
Income available to common stockholders - basic	671	168	1,723	1,484
Weighted average common shares outstanding (in shares)	282	309	288	321
Basic (in USD per share)	$2.38	$0.54	$5.99	$4.63
Diluted earnings per share:	'	'	'	'
Net income attributable to MPC	672	168	1,726	1,486
Income allocated to participating securities, diluted	1	0	3	2
Income available to common stockholders - diluted	$671	$168	$1,723	$1,484
Weighted average common shares outstanding (in shares)	282	309	288	321
Effect of dilutive securities (in shares)	2	2	2	2
Weighted average common shares, including dilutive effect (in shares)	284	311	290	323
Diluted (in USD per share)	$2.36	$0.54	$5.95	$4.60

Income_Per_Common_Share_Antidi

Income Per Common Share - Anti-dilutive Shares (Details) (Stock Compensation Plan)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Compensation Plan	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Shares issued under stock-based compensation plans	0	1	0	1

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)	3 Months Ended			9 Months Ended			33 Months Ended	1 Months Ended	0 Months Ended		9 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014	Oct. 31, 2014	Jul. 30, 2014	Jul. 30, 2014	Sep. 30, 2013
								Scenario, Forecast	Share Repurchase Authorization July 2014	Share Repurchase Authorization July 2014	Accelerated Share Repurchase Program November 2012
Equity, Class of Treasury Stock [Line Items]	'	'		'		'	'	'	'	'	'
Stock repurchase plan authorized amount	$8,000,000,000	'		$8,000,000,000		'	$8,000,000,000	'	'	$2,000,000,000	'
Ending date of share repurchase authorization	'	'		'		'	'	'	30-Jul-16	'	'
Cash paid for shares repurchased	301,000,000	1,028,000,000		1,449,000,000		2,341,000,000	5,590,000,000	9,000,000	'	'	'
Stock repurchase plan remaining authorized amount	$2,410,000,000	'		$2,410,000,000		'	$2,410,000,000	'	'	'	'
Number of shares repurchased	4	14	[1]	17	[1]	31	82	'	'	'	1
Effective average cost per delivered share	$85.15	$70.73		$87.25		$76.01	$68.41	'	'	'	'
[1]	The nine months ended September 30, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in 2012.

Equity_Share_Repurchases_Trans

Equity - Share Repurchases Transacted Through ASR Programs and Open Market Transactions (Detail) (USD $)	3 Months Ended			9 Months Ended			33 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014
Equity, Class of Treasury Stock [Line Items]	'	'		'		'	'
Number of shares repurchased	4	14	[1]	17	[1]	31	82
Cash paid for shares repurchased	$301	$1,028		$1,449		$2,341	$5,590
Effective average cost per delivered share	$85.15	$70.73		$87.25		$76.01	$68.41
Accelerated Share Repurchase Program November 2012	'	'		'		'	'
Equity, Class of Treasury Stock [Line Items]	'	'		'		'	'
Number of shares repurchased	'	'		'		1	'
[1]	The nine months ended September 30, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in 2012.

Segment_Information_Additional

Segment Information - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2014
	Segment
Segment Reporting [Abstract]	'
Number of reportable segments	3

Segment_Information_Income_Fro

Segment Information - Income From Operations Attributable To Operating Segments (Detail) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	$25,438		$26,256		$75,567		$75,263
Income from operations	1,062		301		2,792		2,417
Income (loss) from equity method investments	29		9		121		16
Depreciation and amortization	322		299		967		888
Capital expenditures and investments	3,278	[1],[2],[3]	411	[1],[2],[3]	4,012	[1],[2],[3]	2,268	[1],[2],[3]
Galveston Bay Refinery and Related Assets	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		'		1,360	[2],[3]
Hess' Retail Operations and Related Assets	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		2,680	[3]	'
Intersegment Eliminations	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	2,538	[4]	2,557	[4]	7,623	[4]	7,415	[4]
Operating Segments	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	27,976		28,813		83,190		82,684
Income from operations	1,159	[5]	383	[5]	3,086	[5]	2,690	[5]
Income (loss) from equity method investments	29		9		121		16
Depreciation and amortization	310	[6]	294	[6]	930	[6]	872	[6]
Capital expenditures and investments	3,249	[3],[7]	350	[3]	3,932	[3],[7]	2,147	[3],[8]
Refining & Marketing	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	21,568		22,481		64,295		64,245
Refining & Marketing | Intersegment Eliminations	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	2,400	[4]	2,439	[4]	7,223	[4]	7,072	[4]
Refining & Marketing | Operating Segments	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	23,968		24,920		71,518		71,317
Income from operations	971		227		2,593		2,235
Income (loss) from equity method investments	17		8		76		7
Depreciation and amortization	257	[6]	246	[6]	782	[6]	734	[6]
Capital expenditures and investments	318	[3],[7]	243	[3]	731	[3],[7]	1,797	[2],[3],[8]
Refining & Marketing | Operating Segments | Galveston Bay Refinery and Related Assets	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		'		1,290	[2],[3]
Refining & Marketing | Operating Segments | Hess' Retail Operations and Related Assets	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		54	[3]	'
Speedway	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	3,854		3,755		11,220		10,964
Speedway | Intersegment Eliminations	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	2	[4]	1	[4]	4	[4]	3	[4]
Speedway | Operating Segments	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	3,856		3,756		11,224		10,967
Income from operations	119		102		271		292
Income (loss) from equity method investments	0		0		0		0
Depreciation and amortization	33	[6]	29	[6]	90	[6]	83	[6]
Capital expenditures and investments	2,707	[3],[7]	65	[3]	2,783	[3],[7]	177	[3]
Speedway | Operating Segments | Hess' Retail Operations and Related Assets	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		2,630	[3]	'
Pipeline Transportation	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	16		20		52		60
Pipeline Transportation | Intersegment Eliminations	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	136	[4]	117	[4]	396	[4]	340	[4]
Pipeline Transportation | Operating Segments	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	152		137		448		400
Income from operations	69	[5]	54	[5]	222	[5]	163	[5]
Income (loss) from equity method investments	12		1		45		9
Depreciation and amortization	20	[6]	19	[6]	58	[6]	55	[6]
Capital expenditures and investments	224	[3]	42	[3]	418	[3]	173	[2],[3],[8]
Pipeline Transportation | Operating Segments | Galveston Bay Refinery and Related Assets	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		'		70	[2],[3]
Reportable Segment	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Revenues	$25,438		$26,256		$75,567		$75,269
[1]	Includes capitalized interest of $7 million for both the three months ended September 30, 2014 and 2013, and $20 million and $15 million for the nine months ended September 30, 2014 and 2013, respectively.
[2]	The nine months ended September 30, 2013 includes $1.36 billion for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4 to the unaudited consolidated financial statements.
[3]	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
[4]	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties
[5]	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
[6]	Differences between segment totals and MPC totals represent amounts related to unallocated items and are included in “Items not allocated to segments” in the reconciliation below.
[7]	The Speedway and Refining & Marketing segments include $2.63 billion and $54 million, respectively, for the acquisition of Hess' Retail Operations and Related Assets. See Note 4.
[8]	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4.

Segment_Information_Reconcilia

Segment Information - Reconciliation Of Segment Income From Operations To Income Before Income Taxes (Detail) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'		'		'
Income from operations	$1,062		$301		$2,792		$2,417
Net interest and other financial income (costs)	-50		-47		-144		-140
Income before income taxes	1,012		254		2,648		2,277
Operating Segments	'		'		'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'		'		'
Income from operations	1,159	[1]	383	[1]	3,086	[1]	2,690	[1]
Corporate and Other	'		'		'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'		'		'
Income from operations	-76	[1],[2]	-59	[1],[2]	-204	[1],[2],[3]	-190	[1],[2]
Segment Reconciling Items	'		'		'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'		'		'
Pension settlement expenses	($21)	[4]	($23)	[4]	($90)	[4]	($83)	[4]
[1]	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
[2]	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets.
[3]	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties
[4]	See Note 20.

Segment_Information_Reconcilia1

Segment Information - Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures (Detail) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'		'		'
Capital expenditures and investments	$3,278	[1],[2],[3]	$411	[1],[2],[3]	$4,012	[1],[2],[3]	$2,268	[1],[2],[3]
Plus: Items not allocated to segments:	'		'		'		'
Capital expenditures	3,101	[4],[5]	336	[4],[5]	3,671	[4],[5]	2,182	[4],[5]
Operating Segments	'		'		'		'
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'		'		'
Capital expenditures and investments	3,249	[3],[6]	350	[3]	3,932	[3],[6]	2,147	[3],[7]
Less: Investments in equity method investees	177		75		341		86
Corporate and Other	'		'		'		'
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'		'		'
Capital expenditures and investments	29	[1],[3]	61	[1],[3]	80	[1],[3]	121	[1],[3]
Plus: Items not allocated to segments:	'		'		'		'
Capital expenditures not allocated to segments	22		54		60		106
Capitalized interest	$7		$7		$20		$15
[1]	Includes capitalized interest of $7 million for both the three months ended September 30, 2014 and 2013, and $20 million and $15 million for the nine months ended September 30, 2014 and 2013, respectively.
[2]	The nine months ended September 30, 2013 includes $1.36 billion for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4 to the unaudited consolidated financial statements.
[3]	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
[4]	See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
[5]	Capital expenditures include changes in capital accruals and acquisitions.
[6]	The Speedway and Refining & Marketing segments include $2.63 billion and $54 million, respectively, for the acquisition of Hess' Retail Operations and Related Assets. See Note 4.
[7]	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4.

Segment_Information_Reconcilia2

Segment Information - Reconciliation Of Total Revenues To Sales And Other Operating Revenues (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Sales and other operating revenues (including consumer excise taxes)	$25,438	$26,256	$75,567	$75,263
Corporate and Other	'	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Sales and other operating revenues (including consumer excise taxes)	0	0	0	-6
Reportable Segment	'	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'	'
Sales and other operating revenues (including consumer excise taxes)	$25,438	$26,256	$75,567	$75,269

Segment_Information_Segment_In

Segment Information Segment Information - Total Assets By Reportable Segment (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	$31,705	$28,385
Operating Segments | Refining & Marketing	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	20,207	19,573
Operating Segments | Speedway	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	5,203	2,064
Operating Segments | Pipeline Transportation	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	2,329	1,947
Corporate and Other	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Assets	$3,966	$4,801

Other_Items_Net_Interest_And_O

Other Items - Net Interest And Other Financial Income (Costs) (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest:	'	'	'	'
Interest income	$2	$2	$5	$7
Interest expense	-56	-50	-154	-147
Interest capitalized	7	7	20	15
Total net interest	-47	-41	-129	-125
Other:	'	'	'	'
Net foreign currency gains (losses)	1	-1	0	0
Bank service and other fees	-4	-5	-15	-15
Total other	-3	-6	-15	-15
Net interest and other financial income (costs)	($50)	($47)	($144)	($140)

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'	'
Combined federal, state and foreign income tax rate	33.00%	32.00%	34.00%	34.00%
Statutory rate applied to income before income taxes	'	'	35.00%	'
Tax settlement with Marathon Oil Corporation	'	'	$39	$39
Unrecognized benefits	$16	'	$16	'

Inventories_Summary_Of_Invento

Inventories - Summary Of Inventories (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Crude oil and refinery feedstocks	$2,405	$1,797
Refined products	2,731	2,367
Materials and supplies	308	425
Merchandise	164	100
Total (at cost)	$5,608	$4,689

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Inventory Disclosure [Abstract]	'	'
Impact on revenues and costs as a result of LIFO liquidations	$0	$0

Property_Plant_And_Equipment_S

Property, Plant And Equipment - Summary Of Property, Plant And Equipment (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	$24,712	$21,793
Less accumulated depreciation	8,713	7,872
Net property, plant and equipment	15,999	13,921
Operating Segments | Refining & Marketing	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	17,646	16,982
Operating Segments | Speedway	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	4,477	2,344
Operating Segments | Pipeline Transportation	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	1,995	1,921
Corporate and Other	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	$594	$546

Goodwill_Details

Goodwill (Details) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Goodwill [Line Items]	'		'
Goodwill, beginning balance	$938		'
Goodwill acquired during period	600		'
Goodwill, disposition	-1		'
Goodwill, ending balance	1,537		'
Refining & Marketing	'		'
Goodwill [Line Items]	'		'
Goodwill, beginning balance	551		'
Goodwill acquired during period	0		'
Goodwill, disposition	-1		'
Goodwill, ending balance	550		'
Speedway	'		'
Goodwill [Line Items]	'		'
Goodwill, beginning balance	225		'
Goodwill acquired during period	600	[1]	8
Goodwill, disposition	0		'
Goodwill, ending balance	825		225
Pipeline Transportation	'		'
Goodwill [Line Items]	'		'
Goodwill, beginning balance	162		'
Goodwill acquired during period	0		'
Goodwill, disposition	0		'
Goodwill, ending balance	$162		'
[1]	See Note 4 for information on the acquisitions.

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash collateral netted with derivative liabilities	$0		$32
Liabilities, current	193		159
Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets - netting and collateral	-55	[1]	-21	[1]
Commodity derivative instruments, assets - net	32	[2]	0	[2]
Commodity derivative instruments, assets - collateral pledged not offset	60		61
Other assets	2		2
Total assets at fair value	34		2
Commodity derivative instruments, liabilities - netting and collateral	-55	[1]	-53	[1]
Commodity derivative instruments, liabilities - net	0	[2]	0	[2]
Commodity derivative instruments, liabilities - collateral pledged not offset	0		0
Contingent consideration, liability	475	[3]	625	[3]
Total liabilities at fair value	475		625
Fair Value, Measurements, Recurring | Level 1	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets - gross	87		21
Other assets	2		2
Total assets at fair value	89		23
Commodity derivative instruments, liabilities - gross	55		53
Contingent consideration, liability	0		0
Total liabilities at fair value	55		53
Fair Value, Measurements, Recurring | Level 2	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets - gross	0		0
Other assets	0		0
Total assets at fair value	0		0
Commodity derivative instruments, liabilities - gross	0		0
Contingent consideration, liability	0		0
Total liabilities at fair value	0		0
Fair Value, Measurements, Recurring | Level 3	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets - gross	0		0
Other assets	0		0
Total assets at fair value	0		0
Commodity derivative instruments, liabilities - gross	0		0
Contingent consideration, liability	475	[3]	625	[3]
Total liabilities at fair value	$475		$625
[1]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of September 30, 2014 and December 31, 2013, cash collateral of $0 million and $32 million, respectively, was netted with mark-to-market derivative liabilities.
[2]	We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.
[3]	Includes $193 million and $159 million classified as current at September 30, 2014 and December 31, 2013, respectively.

Fair_Value_Measurements_Narrat

Fair Value Measurements - Narrative (Detail) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Feb. 01, 2013

Sep. 30, 2014

Sep. 30, 2014

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Fair Value, Measurements, Nonrecurring

Fair Value, Measurements, Nonrecurring

Galveston Bay Refinery and Related Assets

Galveston Bay Refinery and Related Assets

Galveston Bay Refinery and Related Assets

Derivative

Derivative

Derivative

Derivative

Contingent Consideration

Contingent Consideration

Contingent Consideration

Contingent Consideration

Fair Value, Measurements, Recurring

Fair Value, Measurements, Recurring

Minimum

Maximum

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum earnout payment, year one

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$200,000,000

'

'

Maximum earnout payment, year two

'

'

'

'

'

'

'

'

'

'

'

'

'

'

200,000,000

'

'

Maximum earnout payment, year three

'

'

'

'

'

'

'

'

'

'

'

'

'

'

200,000,000

'

'

Maximum earnout payment, year four

'

'

'

'

'

'

'

'

'

'

'

'

'

'

250,000,000

'

'

Maximum earnout payment, year five

'

'

'

'

'

'

'

'

'

'

'

'

'

'

250,000,000

'

'

Maximum earnout payment, year six

'

'

'

'

'

'

'

'

'

'

'

'

'

'

250,000,000

'

'

Total cumulative payment capped over six-year period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

700,000,000

'

'

Range of internal and external crack spread forecast per barrel

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

14

15

Discount rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.00%

10.00%

Unrealized (gains) losses included in net income

8,000,000

-5,000,000

30,000,000

6,000,000

0

0

0

0

8,000,000

-5,000,000

30,000,000

6,000,000

'

'

'

'

'

Other asset impairment charges

'

'

'

'

'

'

'

'

'

'

'

'

11,000,000

0

'

'

'

Impairment of long-lived assets held-for-use

'

'

'

'

'

'

'

'

'

'

'

'

$0

$8,000,000

'

'

'

Fair_Value_Measurements_Reconc

Fair Value Measurements - Reconciliation of Net Beginning and Ending Balances Recorded for Net Assets and Liabilities Classified as Level 3 (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Beginning balance	$647	$611	$625	$0
Contingent consideration agreement	0	0	0	600
Contingent consideration payment	-180	0	-180	0
Unrealized (gains) losses included in net income	8	-5	30	6
Ending balance	$475	$606	$475	$606

Fair_Value_Measurements_Fair_V

Fair Value Measurements Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Details) (Fair Value, Measurements, Nonrecurring, USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Measurements, Nonrecurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Property, plant, and equipment, fair value	$0	$1
Impairment of long-lived assets held-for-use	0	8
Other assets, fair value	0	0
Other asset impairment charges	$11	$0

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Instruments at Fair Value, Excluding Derivative Financial Instruments and Contingent Consideration (Detail) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value	'		'
Financial assets:	'		'
Investments	$23		$336
Other assets	31		31
Total financial assets	54		367
Financial liabilities:	'		'
Long-term debt	6,224	[1]	3,306	[1]
Deferred credits and other liabilities	20		21
Total financial liabilities	6,244		3,327
Carrying Value	'		'
Financial assets:	'		'
Investments	2		14
Other assets	29		30
Total financial assets	31		44
Financial liabilities:	'		'
Long-term debt	5,886	[1]	3,001	[1]
Deferred credits and other liabilities	20		21
Total financial liabilities	$5,906		$3,022
[1]	Excludes capital leases

Derivatives_Classification_of_

Derivatives - Classification of Gross Fair Values of Derivative Instruments, Excluding Cash Collateral (Detail) (Commodity derivatives, Other current assets, USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Commodity derivatives | Other current assets	'	'
Derivatives, Fair Value [Line Items]	'	'
Asset	$87	$21
Liability	$55	$53

Derivatives_Open_Commodity_Der

Derivatives - Open Commodity Derivative Contracts (Detail)	9 Months Ended
	Sep. 30, 2014
Crude Oil Exchange-Traded	'
Derivative [Line Items]	'
Percentage of derivative contracts expiring in the period	96.00%
Derivative contract expiration date	31-Dec-14
Crude Oil Exchange-Traded | Long	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	10,346,000	[1]
Crude Oil Exchange-Traded | Short	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	23,186,000	[1]
Refined Products Exchange-Traded	'
Derivative [Line Items]	'
Percentage of derivative contracts expiring in the period	100.00%
Derivative contract expiration date	31-Dec-14
Refined Products Exchange-Traded | Long	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	1,695,000	[2]
Refined Products Exchange-Traded | Short	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	3,281,000	[2]
[1]	96 percent of these contracts expire in the fourth quarter of 2014.
[2]	100 percent of these contracts expire in the fourth quarter of 2014.

Derivatives_Effect_of_Commodit

Derivatives - Effect of Commodity Derivative Instruments in Statements of Income (Detail) (Commodity derivatives, USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss)	$155	($161)	($12)	($166)
Sales and other operating revenues	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss)	10	9	18	13
Cost of revenues	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain (Loss)	$145	($170)	($30)	($179)

Debt_Outstanding_Borrowings_De

Debt - Outstanding Borrowings (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Debt Instrument [Line Items]	'		'
Total	$6,283		$3,395
Unamortized discount	-26		-10
Fair value adjustments	7	[1]	11	[1]
Amounts due within one year	-26		-23
Total long-term debt due after one year	6,238		3,373
Interest Rate Swap	'		'
Debt Instrument [Line Items]	'		'
Deferred gain on discontinuation of interest rate fair value hedge	20		'
Consolidated subsidiaries: | Capital Lease Obligations	'		'
Debt Instrument [Line Items]	'		'
Capital lease obligations	378		395
Debt instrument maturity year, start	1-Jan-14		'
Debt instrument maturity year, end	31-Dec-28		'
MPC Revolver | Line of Credit	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	0		0
Line of credit facility, expiration date	14-Sep-17		'
MPC Term Loan | Unsecured Debt	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	700		0
Line of credit facility, expiration date	30-Sep-19		'
3.500% senior notes due March 1, 2016 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	750		750
Debt instrument, maturity date	1-Mar-16		'
Debt instrument, interest rate	3.50%		'
5.125% senior notes due March 1, 2021 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	1,000		1,000
Debt instrument, maturity date	1-Mar-21		'
Debt instrument, interest rate	5.13%		'
3.625% senior notes due September 15, 2024 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	750		0
Debt instrument, maturity date	15-Sep-24		'
Debt instrument, interest rate	3.63%		'
6.500% senior notes due March 1, 2041 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	1,250		1,250
Debt instrument, maturity date	1-Mar-41		'
Debt instrument, interest rate	6.50%		'
4.750% senior notes due September 15, 2044 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	800		0
Debt instrument, maturity date	15-Sep-44		'
Debt instrument, interest rate	4.75%		'
5.000% senior notes due September 15, 2054 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	400		0
Debt instrument, maturity date	15-Sep-54		'
Debt instrument, interest rate	5.00%		'
MPLX Revolver | MPLX Operations LLC | Line of Credit	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	255		0
Line of credit facility, expiration date	31-Oct-17		'
Trade Receivables Securitization | Consolidated subsidiaries: | Secured Debt	'		'
Debt Instrument [Line Items]	'		'
Long-term debt, gross	$0		$0
Line of credit facility, expiration date	31-Dec-16		'
[1]	The $20 million gain on the termination of our interest rate swap agreements in 2012 is being amortized over the remaining life of the 3.50 percent senior notes.

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
MPLX Revolver | MPLX Operations LLC | Letter of Credit	'	'
Line of Credit Facility [Line Items]	'	'
Borrowings outstanding	$0	'
Line of Credit | MPC Revolver	'	'
Line of Credit Facility [Line Items]	'	'
Long-term debt, gross	0	0
Line of credit facility, expiration date	14-Sep-17	'
Line of Credit | MPLX Revolver | MPLX Operations LLC	'	'
Line of Credit Facility [Line Items]	'	'
Long-term debt, gross	255	0
Line of credit facility, borrowings during period	270	'
Interest rate during period	1.50%	'
Line of credit facility, repayments during period	15	'
Borrowings outstanding	255	'
Remaining borrowing capacity	$245	'
Remaining borrowing capacity, percentage	49.00%	'
Line of credit facility, expiration date	31-Oct-17	'

Debt_Term_Loan_Details

Debt Term Loan (Details) (MPC Term Loan, USD $)	0 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Aug. 26, 2014	Sep. 30, 2014	Aug. 26, 2014
Debt Instrument [Line Items]	'	'	'
Maximum borrowing capacity	'	'	$700
Debt instrument, term	'5 years	'	'
Description of variable rate basis	'Adjusted LIBO Rate (as defined in the Term Loan Agreement)	'	'
Interest rate during period	'	1.30%	'
Maximum	'	'	'
Debt Instrument [Line Items]	'	'	'
Ratio of indebtedness to net capital	0.65	'	0.65
London Interbank Offered Rate (LIBOR) | Minimum	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	0.88%	'	'
London Interbank Offered Rate (LIBOR) | Maximum	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	1.75%	'	'
Base Rate | Minimum	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	0.00%	'	'
Base Rate | Maximum	'	'	'
Debt Instrument [Line Items]	'	'	'
Basis spread on variable rate	0.75%	'	'

Debt_Senior_Notes_Details

Debt Senior Notes (Details) (Senior Notes, USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 05, 2014
Debt Instrument [Line Items]	'	'
Debt instrument, face amount	'	$1,950
Proceeds from (repayments of) debt	1,915	'
3.625% senior notes due September 15, 2024	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, face amount	'	750
4.750% senior notes due September 15, 2044	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, face amount	'	800
5.000% senior notes due September 15, 2054	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, face amount	'	$400

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Net cash provided by operating activities included:	'	'
Interest paid (net of amounts capitalized)	$162	$166
Net income taxes paid to taxing authorities	969	1,027
Non-cash investing and financing activities:	'	'
Capital lease obligations increase	0	61
Property, plant and equipment sold	4	43
Property, plant and equipment acquired	4	0
Acquisition:	'	'
Contingent consideration	0	600	[1]
Payable to seller	$0	$6	[1]
[1]	Acquisition-date fair value of non-cash consideration associated with the Galveston Bay Refinery and Related Assets acquisition.

Supplemental_Cash_Flow_Informa3

Supplemental Cash Flow Information - Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Detail) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Supplemental Cash Flow Elements [Abstract]	'		'		'		'
Additions to property, plant and equipment per consolidated statements of cash flows	'		'		$952		$733
Non-cash additions to property, plant and equipment	'		'		4		0
Acquisitions	'		'		2,714	[1]	1,386	[1]
Asset retirement expenditures	'		'		1		0
Increase in capital accruals	'		'		0		63
Total capital expenditures	$3,101	[2],[3]	$336	[2],[3]	$3,671	[2],[3]	$2,182	[2],[3]
[1]	The 2014 acquisition includes the acquisition of Hess' Retail Operations and Related Assets. The 2013 acquisition includes the acquisition of the Galveston Bay Refinery and Related Assets. The acquisition numbers above include property, plant and equipment and intangibles. See Note 4.
[2]	See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
[3]	Capital expenditures include changes in capital accruals and acquisitions.

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'		'
Beginning balance	'	'	($204)		($464)
Other comprehensive income (loss) before reclassifications	'	'	-82		177
Amounts reclassified from accumulated other comprehensive loss:	'	'	'		'
Amortization - prior service credit	'	'	-38	[1]	-37	[1]
Amortization of actuarial loss	'	'	40	[1]	55	[1]
Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Settlement Gain Loss Before Tax	'	'	90	[1]	83	[1]
Tax effect	'	'	-34		-19
Other comprehensive income (loss)	-10	49	-24		259
Ending balance	-228	-205	-228		-205
Accumulated Defined Benefit Plans Adjustment | Pension Benefits	'	'	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'		'
Beginning balance	'	'	-161		-432
Other comprehensive income (loss) before reclassifications	'	'	-88		172
Amounts reclassified from accumulated other comprehensive loss:	'	'	'		'
Amortization - prior service credit	'	'	-35	[1]	-34	[1]
Amortization of actuarial loss	'	'	38	[1]	53	[1]
Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Settlement Gain Loss Before Tax	'	'	90	[1]	83	[1]
Tax effect	'	'	-35		-19
Other comprehensive income (loss)	'	'	-30		255
Ending balance	-191	-177	-191		-177
Accumulated Defined Benefit Plans Adjustment | Other Benefits	'	'	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'		'
Beginning balance	'	'	-50		-36
Other comprehensive income (loss) before reclassifications	'	'	8		3
Amounts reclassified from accumulated other comprehensive loss:	'	'	'		'
Amortization - prior service credit	'	'	-3	[1]	-3	[1]
Amortization of actuarial loss	'	'	2	[1]	2	[1]
Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Settlement Gain Loss Before Tax	'	'	0		0
Tax effect	'	'	1		0
Other comprehensive income (loss)	'	'	8		2
Ending balance	-42	-34	-42		-34
Gain on Cash Flow Hedge	'	'	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'		'
Beginning balance	'	'	4		4
Other comprehensive income (loss) before reclassifications	'	'	0		0
Amounts reclassified from accumulated other comprehensive loss:	'	'	'		'
Tax effect	'	'	0		0
Other comprehensive income (loss)	'	'	0		0
Ending balance	4	4	4		4
Workers Compensation	'	'	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'		'
Beginning balance	'	'	3		0
Other comprehensive income (loss) before reclassifications	'	'	-2		2
Amounts reclassified from accumulated other comprehensive loss:	'	'	'		'
Tax effect	'	'	0		0
Other comprehensive income (loss)	'	'	-2		2
Ending balance	$1	$2	$1		$2
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 20.

Defined_Benefit_Pension_and_Ot2

Defined Benefit Pension and Other Postretirement Plans - Components of Net Periodic Benefit Costs (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits	'	'	'	'
Components of net periodic benefit cost:	'	'	'	'
Service cost	$24	$24	$67	$70
Interest cost	18	19	56	55
Expected return on plan assets	-27	-28	-81	-81
Amortization – prior service credit	-12	-12	-35	-34
Amortization – actuarial loss	12	14	38	53
Amortization - settlement loss	21	23	90	83
Net periodic benefit cost	36	40	135	146
Other Benefits	'	'	'	'
Components of net periodic benefit cost:	'	'	'	'
Service cost	7	7	20	19
Interest cost	7	6	24	19
Expected return on plan assets	0	0	0	0
Amortization – prior service credit	-1	-1	-3	-3
Amortization – actuarial loss	1	1	2	2
Amortization - settlement loss	0	0	0	0
Net periodic benefit cost	$14	$13	$43	$37

Defined_Benefit_Pension_and_Ot3

Defined Benefit Pension and Other Postretirement Plans - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Pension settlement expenses	($21)	($23)	($90)	($83)
Pension Benefits | Funded Pension Plans	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Employer contributions	'	'	16	'
Pension Benefits | Unfunded Pension Plans	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Defined benefit plan, benefits paid	'	'	22	'
Other Benefits	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Pension settlement expenses	0	0	0	0
Other Benefits | Unfunded Pension Plans	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Defined benefit plan, benefits paid	'	'	$17	'

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans - Summary of Stock Option Award Activity (Detail) (Stock Options, USD $)	9 Months Ended
	Sep. 30, 2014
Stock Options	'
Number of Shares	'
Outstanding, beginning balance	5,147,837	[1]
Granted	446,310	[1]
Exercised	-696,159	[1]
Forfeited, canceled or expired	-20,761	[1]
Outstanding, ending balance	4,877,227	[1]
Weighted Average Exercise Price	'
Outstanding, beginning balance (in USD per share)	$40.08
Granted (in USD per share)	$85.02
Exercised (in USD per share)	$32.12
Forfeited, canceled or expired (in USD per share)	$49.67
Outstanding, ending balance (in USD per share)	$45.28
[1]	Includes an immaterial number of stock appreciation rights.

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans - Narrative (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014
Stock Options	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Grant date fair value (in USD per share)	$25.37
Implied volatility rate weighting (in percentage)	50.00%
Historical volatility rate weighting (in percentage)	50.00%
Performance Unit Awards	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Grant date fair value (in USD per unit)	$0.85

StockBased_Compensation_Plans_3

Stock-Based Compensation Plans - Summary of Restricted Stock Award Activity (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014
Restricted Stock	'
Number of Shares	'
Outstanding, beginning balance	624,122
Granted	240,882
RS's Vested/RSU's Issued	-324,697
Forfeited	-25,943
Outstanding, ending balance	514,364
Weighted Average Grant Date Fair Value	'
Outstanding, beginning balance (in USD per share)	$61.11
Granted (in USD per share)	$87.81
RS's Vested/RSU's Issued (in USD per share)	$55.47
Forfeited (in USD per share)	$70.10
Outstanding, ending balance (in USD per share)	$76.73
Restricted Stock Units	'
Number of Shares	'
Outstanding, beginning balance	385,079
Granted	19,827
RS's Vested/RSU's Issued	-398
Forfeited	-133
Outstanding, ending balance	404,375
Weighted Average Grant Date Fair Value	'
Outstanding, beginning balance (in USD per share)	$33.96
Granted (in USD per share)	$86.79
RS's Vested/RSU's Issued (in USD per share)	$60.11
Forfeited (in USD per share)	$76.10
Outstanding, ending balance (in USD per share)	$36.51

StockBased_Compensation_Plans_4

Stock-Based Compensation Plans - Summary of Performance Unit Awards (Detail) (Performance Unit Awards)	9 Months Ended
	Sep. 30, 2014
Performance Unit Awards	'
Number of Units	'
Outstanding, beginning balance	3,822,500
Granted	2,033,700
Settled	0
Canceled	0
Outstanding, ending balance	5,856,200

Commitments_and_Contingencies_

Commitments and Contingencies (Detail) (USD $)

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Galveston Bay Refinery and Related Assets

North Dakota Pipeline

Illinois Extension Pipeline Company LLC

Indemnification Agreement

Other Guarantees

Guarantee of Indebtedness of Others

Master Shelf Agreement

Standby Letters of Credit

Pending Litigation

Pending Litigation

Marathon Oil Companies

Equity method investees

Financial Guarantee

Financial Guarantee

Financial Guarantee

Emergency Pricing And Consumer Protection Laws

LOOP and LOCAP LLC

Centennial

TAME

Loss Contingencies [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Loss contingency, inestimable loss

'

'

'

'

'

'

'

'

'

'

'For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings and discovery.

'

Accrued liabilities for remediation

$182

$123

'

'

'

'

'

'

'

'

'

'

Receivables for recoverable costs

71

51

'

'

'

'

'

'

'

'

'

'

Alleged amount overcharged from customers

'

'

'

'

'

'

'

'

'

'

'

89

Loss contingency, period of occurrence

'

'

'

'

'

'

'

'

'

'

'

'during September and October 2005

Plaintiff

'

'

'

'

'

'

'

'

'

'

'

'Commonwealth of Kentucky

Line of credit facility, expiration date

'

'

'

'

'

'

'

31-Dec-37

31-Dec-24

31-Dec-18

'

'

Maximum potential undiscounted payments

'

'

'

'

'

'

122

172

39

25

'

'

Percentage of credit agreement agreed to reimburse

'

'

'

'

'

'

'

'

'

50.00%

'

'

Guarantee obligation current carrying value

'

'

'

'

'

2

'

'

'

'

'

'

Guarantee obligations maximum exposure per event

'

'

'

'

'

'

50

'

'

'

'

'

Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees

$1,800

'

$520

$751

$208

'

'

'

'

'

'

'

Subsequent_Event_Sale_of_remai

Subsequent Event Sale of remaining interest in Pipe Line Holdings (Details) (MPLX Pipe Line Holdings LP)	Mar. 01, 2014	1-May-13	Oct. 29, 2014
			Scenario, Forecast
			Subsequent Event
Subsequent Event [Line Items]	'	'	'
Additional interest sold	13.00%	5.00%	31.00%

Supplementary_Statistics_Suppl

Supplementary Statistics - Supplementary Statistics (Detail) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Supplementary Statistics [Line Items]	'		'		'		'
Income from operations	$1,062		$301		$2,792		$2,417
Capital expenditures and investments	3,278	[1],[2],[3]	411	[1],[2],[3]	4,012	[1],[2],[3]	2,268	[1],[2],[3]
Hess' Retail Operations and Related Assets	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		2,680	[3]	'
Galveston Bay Refinery and Related Assets	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		'		1,360	[2],[3]
Operating Segments	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Income from operations	1,159	[4]	383	[4]	3,086	[4]	2,690	[4]
Capital expenditures and investments	3,249	[3],[5]	350	[3]	3,932	[3],[5]	2,147	[3],[6]
Operating Segments | Refining & Marketing	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Income from operations	971		227		2,593		2,235
Capital expenditures and investments	318	[3],[5]	243	[3]	731	[3],[5]	1,797	[2],[3],[6]
Operating Segments | Refining & Marketing | Hess' Retail Operations and Related Assets	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		54	[3]	'
Operating Segments | Refining & Marketing | Galveston Bay Refinery and Related Assets	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		'		1,290	[2],[3]
Operating Segments | Speedway	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Income from operations	119		102		271		292
Capital expenditures and investments	2,707	[3],[5]	65	[3]	2,783	[3],[5]	177	[3]
Operating Segments | Speedway | Hess' Retail Operations and Related Assets	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		2,630	[3]	'
Operating Segments | Pipeline Transportation	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Income from operations	69	[4]	54	[4]	222	[4]	163	[4]
Capital expenditures and investments	224	[3]	42	[3]	418	[3]	173	[2],[3],[6]
Operating Segments | Pipeline Transportation | Galveston Bay Refinery and Related Assets	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Capital expenditures and investments	'		'		'		70	[2],[3]
Corporate and Other	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Income from operations	-76	[4],[7]	-59	[4],[7]	-204	[4],[7],[8]	-190	[4],[7]
Capital expenditures and investments	29	[1],[3]	61	[1],[3]	80	[1],[3]	121	[1],[3]
Capitalized interest	7		7		20		15
Segment Reconciling Items	'		'		'		'
Supplementary Statistics [Line Items]	'		'		'		'
Pension settlement expenses	($21)	[9]	($23)	[9]	($90)	[9]	($83)	[9]
[1]	Includes capitalized interest of $7 million for both the three months ended September 30, 2014 and 2013, and $20 million and $15 million for the nine months ended September 30, 2014 and 2013, respectively.
[2]	The nine months ended September 30, 2013 includes $1.36 billion for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4 to the unaudited consolidated financial statements.
[3]	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
[4]	Corporate overhead expenses attributable to MPLX are included in the Pipeline Transportation segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
[5]	The Speedway and Refining & Marketing segments include $2.63 billion and $54 million, respectively, for the acquisition of Hess' Retail Operations and Related Assets. See Note 4.
[6]	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4.
[7]	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets.
[8]	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties
[9]	See Note 20.

Supplementary_Statistics_Opera

Supplementary Statistics - Operating Statistics (Detail) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
	BPD		BPD		BPD		BPD
Operating Statistics [Line Items ]	'		'		'		'
MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)	2,155,000	[1],[2]	2,155,000	[1],[2]	2,092,000	[1],[2]	2,063,000	[1],[2]
Refining & Marketing	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refining & Marketing refined product sales volume (thousands of barrels per day)	2,140,000	[1],[3]	2,148,000	[1],[3]	2,079,000	[1],[4]	2,052,000	[1],[4]
Refining & Marketing gross margin (dollars per barrel)	14.55	[1],[5]	9.25	[1],[5]	15.02	[1],[5]	12.42	[1],[5]
Crude oil capacity utilization percent	100.00%	[1],[6]	99.00%	[1],[6]	94.00%	[1],[6]	97.00%	[1],[6]
Refinery throughputs (thousands of barrels per day)	1,880,000	[1],[7]	1,877,000	[1],[7]	1,788,000	[1],[7]	1,805,000	[1],[7]
Sour crude oil throughput percent	52.00%	[1]	53.00%	[1]	52.00%	[1]	53.00%	[1]
WTI-priced crude oil throughput percent	16.00%	[1]	21.00%	[1]	18.00%	[1]	22.00%	[1]
Refined product yields (thousands of barrels per day)	1,915,000	[1],[7]	1,915,000	[1],[7]	1,820,000	[1],[7]	1,839,000	[1],[7]
Inter-refinery transfers	33,000		36,000		45,000		34,000
Refinery direct operating costs (dollars per barrel):	'		'		'		'
Planned turnaround and major maintenance	1.52	[1],[8]	0.96	[1],[8]	1.82	[1],[8]	0.94	[1],[8]
Depreciation and amortization	1.35	[1],[8]	1.27	[1],[8]	1.43	[1],[8]	1.32	[1],[8]
Other manufacturing	4.33	[1],[8],[9]	4.1	[1],[8],[9]	4.96	[1],[8],[9]	4	[1],[8],[9]
Total	7.2	[1],[8]	6.33	[1],[8]	8.21	[1],[8]	6.26	[1],[8]
Refining & Marketing | Crude oil refined	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	1,720,000	[1],[7]	1,682,000	[1],[7]	1,616,000	[1],[7]	1,603,000	[1],[7]
Refining & Marketing | Other charge and blendstocks	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	160,000	[1],[7]	195,000	[1],[7]	172,000	[1],[7]	202,000	[1],[7]
Refining & Marketing | Gasoline	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	864,000	[1],[7]	938,000	[1],[7]	851,000	[1],[7]	917,000	[1],[7]
Refining & Marketing | Distillates	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	598,000	[1],[7]	578,000	[1],[7]	574,000	[1],[7]	570,000	[1],[7]
Refining & Marketing | Propane	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	36,000	[1],[7]	39,000	[1],[7]	36,000	[1],[7]	37,000	[1],[7]
Refining & Marketing | Feedstocks and special products	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	330,000	[1],[7]	259,000	[1],[7]	280,000	[1],[7]	227,000	[1],[7]
Refining & Marketing | Heavy fuel oil	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	24,000	[1],[7]	31,000	[1],[7]	27,000	[1],[7]	31,000	[1],[7]
Refining & Marketing | Asphalt	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	63,000	[1],[7]	70,000	[1],[7]	52,000	[1],[7]	57,000	[1],[7]
Refining & Marketing | Gulf Coast:	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	1,230,000	[1],[10]	1,210,000	[1],[10]	1,163,000	[1],[10]	1,152,000	[1],[10]
Sour crude oil throughput percent	66.00%	[1]	64.00%	[1]	64.00%	[1]	65.00%	[1]
WTI-priced crude oil throughput percent	1.00%	[1]	7.00%	[1]	2.00%	[1]	8.00%	[1]
Refined product yields (thousands of barrels per day)	1,256,000	[1],[10]	1,240,000	[1],[10]	1,189,000	[1],[10]	1,179,000	[1],[10]
Refinery direct operating costs (dollars per barrel):	'		'		'		'
Planned turnaround and major maintenance	1.15	[1],[8]	0.86	[1],[8]	1.77	[1],[8]	0.77	[1],[8]
Depreciation and amortization	1.1	[1],[8]	1.01	[1],[8]	1.16	[1],[8]	1.04	[1],[8]
Other manufacturing	4.11	[1],[8],[9]	4.08	[1],[8],[9]	4.86	[1],[8],[9]	3.82	[1],[8],[9]
Total	6.36	[1],[8]	5.95	[1],[8]	7.79	[1],[8]	5.63	[1],[8]
Refining & Marketing | Gulf Coast: | Crude oil refined	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	1,075,000	[1],[10]	1,035,000	[1],[10]	989,000	[1],[10]	971,000	[1],[10]
Refining & Marketing | Gulf Coast: | Other charge and blendstocks	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	155,000	[1],[10]	175,000	[1],[10]	174,000	[1],[10]	181,000	[1],[10]
Refining & Marketing | Gulf Coast: | Gasoline	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	505,000	[1],[10]	561,000	[1],[10]	498,000	[1],[10]	545,000	[1],[10]
Refining & Marketing | Gulf Coast: | Distillates	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	389,000	[1],[10]	370,000	[1],[10]	366,000	[1],[10]	363,000	[1],[10]
Refining & Marketing | Gulf Coast: | Propane	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	25,000	[1],[10]	24,000	[1],[10]	24,000	[1],[10]	23,000	[1],[10]
Refining & Marketing | Gulf Coast: | Feedstocks and special products	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	310,000	[1],[10]	241,000	[1],[10]	275,000	[1],[10]	214,000	[1],[10]
Refining & Marketing | Gulf Coast: | Heavy fuel oil	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	8,000	[1],[10]	21,000	[1],[10]	13,000	[1],[10]	20,000	[1],[10]
Refining & Marketing | Gulf Coast: | Asphalt	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	19,000	[1],[10]	23,000	[1],[10]	13,000	[1],[10]	14,000	[1],[10]
Refining & Marketing | Midwest:	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	683,000	[10]	703,000	[10]	670,000	[10]	687,000	[10]
Sour crude oil throughput percent	30.00%		35.00%		33.00%		35.00%
WTI-priced crude oil throughput percent	41.00%		43.00%		42.00%		43.00%
Refined product yields (thousands of barrels per day)	692,000	[10]	711,000	[10]	676,000	[10]	694,000	[10]
Refinery direct operating costs (dollars per barrel):	'		'		'		'
Planned turnaround and major maintenance	2.1	[8]	1.08	[8]	1.78	[1],[8]	1.17	[1],[8]
Depreciation and amortization	1.75	[8]	1.66	[8]	1.8	[8]	1.72	[8]
Other manufacturing	4.51	[8],[9]	3.91	[8],[9]	4.82	[1],[8],[9]	4.1	[1],[8],[9]
Total	8.36	[8]	6.65	[8]	8.4	[8]	6.99	[8]
Refining & Marketing | Midwest: | Crude oil refined	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	645,000	[10]	647,000	[10]	627,000	[10]	632,000	[10]
Refining & Marketing | Midwest: | Other charge and blendstocks	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refinery throughputs (thousands of barrels per day)	38,000	[10]	56,000	[10]	43,000	[10]	55,000	[10]
Refining & Marketing | Midwest: | Gasoline	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	359,000	[10]	377,000	[10]	353,000	[10]	373,000	[10]
Refining & Marketing | Midwest: | Distillates	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	209,000	[10]	208,000	[10]	208,000	[10]	207,000	[10]
Refining & Marketing | Midwest: | Propane	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	13,000	[10]	15,000	[10]	13,000	[10]	14,000	[10]
Refining & Marketing | Midwest: | Feedstocks and special products	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	51,000	[10]	54,000	[10]	49,000	[10]	46,000	[10]
Refining & Marketing | Midwest: | Heavy fuel oil	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	16,000	[10]	10,000	[10]	14,000	[10]	11,000	[10]
Refining & Marketing | Midwest: | Asphalt	'		'		'		'
Refining & Marketing Operating Statistics	'		'		'		'
Refined product yields (thousands of barrels per day)	44,000	[10]	47,000	[10]	39,000	[10]	43,000	[10]
Speedway	'		'		'		'
Speedway Operating Statistics	'		'		'		'
Convenience stores at period-end(j)	2,744	[11]	1,471		2,744	[11]	1,471
Gasoline and distillate sales (millions of gallons)	842,000,000		803,000,000		2,421,000,000		2,329,000,000
Gasoline and distillate gross margin (dollars per gallon)	0.1596	[12]	0.1404	[13]	0.1351	[12]	0.1483	[12]
Merchandise sales (in millions)	870		843		2,422		2,360
Merchandise gross margin (in millions)	235		224		651		620
Merchandise margin percent	27.00%		26.50%		26.90%		26.30%
Same store gasoline sales volume (period over period) percentage	-0.80%		1.00%		-1.00%		0.60%
Merchandise sales excluding cigarettes (period over period) percentage	4.80%	[13]	5.60%	[13]	4.80%	[13]	3.80%	[13]
Speedway | Hess' Retail Operations and Related Assets	'		'		'		'
Speedway Operating Statistics	'		'		'		'
Convenience stores at period-end(j)	1,245	[11]	'		1,245	[11]	'
Pipeline Transportation	'		'		'		'
Pipeline Transportation Operating Statistics	'		'		'		'
Pipeline throughputs (thousands of barrels per day)	2,104,000	[14]	2,230,000	[14]	2,073,000	[14]	2,238,000	[14]
Pipeline Transportation | Crude oil pipelines	'		'		'		'
Pipeline Transportation Operating Statistics	'		'		'		'
Pipeline throughputs (thousands of barrels per day)	1,265,000	[14]	1,317,000	[14]	1,230,000	[14]	1,308,000	[14]
Pipeline Transportation | Refined products pipelines	'		'		'		'
Pipeline Transportation Operating Statistics	'		'		'		'
Pipeline throughputs (thousands of barrels per day)	839,000	[14]	913,000	[14]	843,000	[14]	930,000	[14]
[1]	Includes the impact of the Galveston Bay Refinery and Related Assets beginning on the February 1, 2013 acquisition date.
[2]	Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers.
[3]	Includes intersegment sales.
[4]	The nine months ended September 30, 2013 includes $1.36 billion for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4 to the unaudited consolidated financial statements.
[5]	Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs.
[6]	Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities.
[7]	Excludes inter-refinery volumes of 33 mbpd and 36 mbpd for the three months ended September 30, 2014 and 2013, respectively, and 45 mbpd and 34 mbpd for the nine months ended September 30, 2014 and 2013, respectively.
[8]	Per barrel of total refinery throughputs.
[9]	Includes utilities, labor, routine maintenance and other operating costs.
[10]	Includes inter-refinery transfer volumes.
[11]	Includes 1,245 stores acquired on September 30, 2014 through the acquisition of Hess' Retail Operations and Related Assets. Segment results for the period prior to the acquisition do not include results from these operations.
[12]	The price paid by consumers less the cost of refined products, including transportation, consumer excise taxes and bankcard processing fees, divided by gasoline and distillate sales volume.
[13]	Excludes cigarettes.
[14]	On owned common-carrier pipelines, excluding equity method investments.