Marathon Petroleum (MPC) 10-Q 5 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 30, 2014
Document Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	'Q1	'
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	'	288,632,472

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues and other income:	'	'
Sales and other operating revenues (including consumer excise taxes)	$23,285	$23,330
Income from equity method investments	35	0
Net gain on disposal of assets	1	1
Other income	24	14
Total revenues and other income	23,345	23,345
Costs and expenses:	'	'
Cost of revenues (excludes items below)	20,540	20,034
Purchases from related parties	159	72
Consumer excise taxes	1,515	1,458
Depreciation and amortization	320	287
Selling, general and administrative expenses	346	249
Other taxes	104	89
Total costs and expenses	22,984	22,189
Income from operations	361	1,156
Net interest and other financial income (costs)	-46	-48
Income before income taxes	315	1,108
Provision for income taxes	108	378
Net income	207	730
Less net income attributable to noncontrolling interests	8	5
Net income attributable to MPC	$199	$725
Basic:	'	'
Net income attributable to MPC per share	$0.68	$2.19
Weighted average shares outstanding (in shares)	293	331
Diluted:	'	'
Net income attributable to MPC per share	$0.67	$2.17
Weighted average shares outstanding (in shares)	295	333
Dividends paid (in USD per share)	$0.42	$0.35

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net income	$207	$730
Defined benefit postretirement and post-employment plans:	'	'
Actuarial changes, net of tax of $4 and $54	7	90
Prior service costs, net of tax of ($5) and ($5)	-8	-8
Other comprehensive income (loss)	-1	82
Comprehensive income	206	812
Less comprehensive income attributable to noncontrolling interests	8	5
Comprehensive income attributable to MPC	$198	$807

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Actuarial changes, tax	$4	$54
Prior service costs, tax	($5)	($5)

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$2,166	$2,292
Receivables, less allowance for doubtful accounts of $9 and $9	5,420	5,559
Inventories	5,689	4,689
Other current assets	173	197
Total current assets	13,448	12,737
Equity method investments	602	463
Property, plant and equipment, net	13,854	13,921
Goodwill	938	938
Other noncurrent assets	317	326
Total assets	29,159	28,385
Current liabilities:	'	'
Accounts payable	9,313	8,234
Payroll and benefits payable	259	406
Consumer excise taxes payable	371	373
Accrued taxes	614	513
Long-term debt due within one year	24	23
Other current liabilities	265	275
Total current liabilities	10,846	9,824
Long-term debt	3,635	3,373
Deferred income taxes	2,290	2,304
Defined benefit postretirement plan obligations	855	771
Deferred credits and other liabilities	775	781
Total liabilities	18,401	17,053
Commitments and contingencies (see Note 20)	'	'
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 - 73 million and 65 million shares	-4,849	-4,155
Additional paid-in capital	9,803	9,768
Retained earnings	5,591	5,507
Accumulated other comprehensive loss	-205	-204
Total MPC stockholders’ equity	10,344	10,920
Noncontrolling interests	414	412
Total equity	10,758	11,332
Total liabilities and equity	$29,159	$28,385

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$9	$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	-73,000,000	-65,000,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities:	'	'
Net income	$207	$730
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	320	287
Pension and other postretirement benefits, net	82	28
Deferred income taxes	-14	6
Net gain on disposal of assets	-1	-1
Equity method investments, net	6	4
Changes in the fair value of derivative instruments	-25	-57
Changes in:	'	'
Current receivables	139	-884
Inventories	-1,000	-517
Current accounts payable and accrued liabilities	1,011	2,491
All other, net	41	-8
Net cash provided by operating activities	766	2,079
Investing activities:	'	'
Additions to property, plant and equipment	-267	-195
Acquisitions	0	-1,493
Disposal of assets	2	3
Investments—acquisitions, loans and contributions	-123	-21
Investments—redemptions and repayments	0	11
All other, net	28	13
Net cash used in investing activities	-360	-1,682
Financing activities:	'	'
Long-term debt – borrowings	270	0
Long-term debt – repayments	-6	-5
Debt issuance costs	0	-2
Issuance of common stock	13	28
Common stock repurchased	-689	-431
Dividends paid	-123	-116
Distributions to noncontrolling interests	-6	-4
All other, net	9	10
Net cash used in financing activities	-532	-520
Net decrease in cash and cash equivalents	-126	-123
Cash and cash equivalents at beginning of period	2,292	4,860
Cash and cash equivalents at end of period	$2,166	$4,737

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
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	'	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]		'	'	'	'	'	'	'
Net income		730	'	'	'	725	'	5
Dividends declared		-116	'	'	'	-116	'	'
Distributions to noncontrolling interests		-4	'	'	'	'	'	-4
Other comprehensive income		82	'	'	'	'	82	'
Shares repurchased		-431	'	-531	100	'	'	'
Shares issued (returned)—stock based compensation		24	'	-3	27	'	'	'
Stock-based compensation		22	'	'	22	'	'	0
Number of shares repurchased	[1]	-6	'	'	'	'	'	'
Ending balance at Mar. 31, 2013		12,412	4	-1,787	9,676	4,489	-382	412
Number of shares held in treasury (ending balance) at Mar. 31, 2013		-34	'	'	'	'	'	'
Number of common shares issued (ending balance) at Mar. 31, 2013		361	'	'	'	'	'	'
Beginning balance at Dec. 31, 2013		11,332	4	-4,155	9,768	5,507	-204	412
Number of shares held in treasury (beginning balance) at Dec. 31, 2013		-65	'	'	'	'	'	'
Number of common shares issued (beginning balance) at Dec. 31, 2013		362	'	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]		'	'	'	'	'	'	'
Net income		207	'	'	'	199	'	8
Dividends declared		-124	'	'	'	-124	'	'
Distributions to noncontrolling interests		-6	'	'	'	'	'	-6
Other comprehensive income		-1	'	'	'	'	-1	'
Shares repurchased		-689	'	-689	0	'	'	'
Shares issued (returned)—stock based compensation		9	'	-5	14	'	'	'
Stock-based compensation		21	'	'	21	'	'	0
Other		9	'	'	'	9	'	'
Number of shares issued - stock-based compensation		1	'	'	'	'	'	'
Number of shares repurchased		-8	'	'	'	'	'	'
Ending balance at Mar. 31, 2014		$10,758	$4	($4,849)	$9,803	$5,591	($205)	$414
Number of shares held in treasury (ending balance) at Mar. 31, 2014		-73	'	'	'	'	'	'
Number of common shares issued (ending balance) at Mar. 31, 2014		363	'	'	'	'	'	'
[1]	The three months ended March 31, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in the fourth quarter of 2012.

Description_of_the_Business_an

Description of the Business and Basis of Presentation	3 Months Ended
	Mar. 31, 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 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 8 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 (“US 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 months ended March 31, 2014 are not necessarily indicative of the results to be expected for the full year.
	During the three months ended March 31, 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 three months ended March 31, 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	3 Months Ended
	Mar. 31, 2014
Accounting Changes and Error Corrections [Abstract]	'
Accounting Standards	'
	Accounting Standards
	Not Yet Adopted
	In April 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update which 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(s) of an entity or the classification of a component(s) of an entity as held for sale which 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	3 Months Ended
	Mar. 31, 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 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, with the excess cash paid over historical carrying value recorded as a change within equity. We did not record a gain or loss on the transactions.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2014
Business Combinations [Abstract]	'
Acquisitions and Investments	'
	Acquisitions and Investments
	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 to BP a contingent earnout of up to an additional $700 million over six years, subject to certain conditions. During the second quarter of 2014, we expect to pay BP approximately $178 million for the first year's contingent earnout. See Note 13 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. The pro forma financial information does not give effect to potential synergies that could result from the acquisition and is not necessarily indicative of the results of future operations.
	(In millions, except per share data)	Three Months Ended March 31, 2013
	Sales and other operating revenues (including consumer excise taxes)	$	25,296
	Net income attributable to MPC	780
	Net income attributable to MPC per share - basic	$	2.36
	Net income attributable to MPC per share - diluted	2.34
	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 and 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.
	Assuming these transactions 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, 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
	We made contributions of $37 million to North Dakota Pipeline Company LLC ("North Dakota Pipeline") during the three months ended March 31, 2014. We have contributed $61 million since project inception. These contributions funded 37.5 percent of the construction costs incurred to-date on the Sandpiper pipeline project. In conjunction with our commitment to be an anchor shipper for the Sandpiper pipeline and our investment in the project, we will earn an approximate 27 percent equity interest in Enbridge Energy Partner L.P.'s North Dakota System when the Sandpiper pipeline is placed into service, which is projected to occur in 2016. We also have the option to increase our ownership interest to approximately 30 percent through additional investments in future system improvements. We account for our interest in North Dakota Pipeline using the equity method of accounting. See Note 20 for information on future contributions to North Dakota Pipeline.
	In March 2014, we acquired from Chevron Raven Ridge Pipe Line Company an additional 7 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.

Related_Party_Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2014
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	Related Party Transactions
	Our related parties include:
	•	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.
	•	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.
	•	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
		March 31,
	(In millions)	2014		2013
	Other equity method investees	$	2	$	2
	Purchases from related parties were as follows:
		Three Months Ended
		March 31,
	(In millions)	2014		2013
	Centennial	$	9	$	—
	Explorer	13		—
	LOCAP	5		4
	LOOP	53		10
	TAAE	16		—
	TACE	27		26
	TAME	34		30
	Other equity method investees	2		2
	Total	$	159	$	72
	Related party purchases from Centennial consist primarily of refinery feedstocks. 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.
	Receivables from related parties, which are included in receivables, less allowance for doubtful accounts on the consolidated balance sheets, were as follows:
	(In millions)	March 31,		December 31,
		2014		2013
	Centennial	$	—	$	1
	Explorer	5		—
	TAME	—		1
	Total	$	5	$	2
	We also had a long-term receivable from Centennial of $2 million at March 31, 2014 and 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)	March 31,		December 31,
		2014		2013
	Explorer	$	4	$	—
	LOCAP	2		2
	LOOP	4		3
	TAAE	2		2
	TACE	4		4
	TAME	7		5
	Total	$	23	$	16

Income_per_Common_Share

Income per Common Share	3 Months Ended
	Mar. 31, 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.
	Excluded from the diluted share calculation for both the three months ended March 31, 2014 and 2013 are less than one million shares related to stock-based compensation awards as their effect would be 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
		March 31,
	(In millions, except per share data)	2014		2013
	Basic earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	199	$	725
	Income allocated to participating securities	—		1
	Income available to common stockholders - basic	$	199	$	724
	Weighted average common shares outstanding	293		331
	Basic earnings per share	$	0.68	$	2.19
	Diluted earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	199	$	725
	Income allocated to participating securities	—		1
	Income available to common stockholders - diluted	$	199	$	724
	Weighted average common shares outstanding	293		331
	Effect of dilutive securities	2		2
	Weighted average common shares, including dilutive effect	295		333
	Diluted earnings per share	$	0.67	$	2.17

Equity

Equity	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Equity	'
	Equity
	Our board of directors has approved $6.0 billion in total share repurchase authorizations since January 1, 2012. As of March 31, 2014, we have repurchased a total of $4.83 billion of our common stock under these authorizations, leaving $1.17 billion available for repurchases through September 2015. Under these authorizations, we have acquired 73 million shares at an average cost per share of $66.19.
	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 months ended March 31, 2014 and 2013:
		Three Months Ended
		March 31,
	(In millions, except per share data)	2014		2013
	Number of shares repurchased(a)	8		6
	Cash paid for shares repurchased	$	689	$	431
	Effective average cost per delivered share	$	87.6	$	80.95
	(a)	The three months ended March 31, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in the fourth quarter of 2012.
	At March 31, 2014, we had agreements to acquire additional common shares for $12 million, which were settled in early April 2014.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 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 they offer.
	•	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 – sells transportation fuels and convenience products in retail markets in the Midwest, primarily through Speedway® convenience stores; and
	•	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. Segment information for the period prior to the acquisition does 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 March 31, 2014
	Revenues:
	Customer	$	19,810		$	3,458		$	17	$	23,285
	Intersegment(a)	2,233			1			129		2,363
	Segment revenues	$	22,043		$	3,459		$	146	$	25,648
	Segment income from operations(b)	$	362		$	58		$	72	$	492
	Income from equity method investments	24			—			11		35
	Depreciation and amortization(c)	261			28			19		308
	Capital expenditures and investments(d)	178			32			130		340
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation		Total
	Three Months Ended March 31, 2013
	Revenues:
	Customer	$	19,874		$	3,441		$	21	$	23,336
	Intersegment(a)	2,199			1			104		2,304
	Segment revenues	$	22,073		$	3,442		$	125	$	25,640
	Segment income from operations(b)	$	1,105		$	67		$	51	$	1,223
	Income (loss) from equity method investments	(4		)	—			4		—
	Depreciation and amortization(c)	236			27			18		281
	Capital expenditures and investments(d)(e)	1,420			36			90		1,546
	(a)	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.
	(b)	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These 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.
	(e)	The Refining & Marketing and Pipeline Transportation segments include the acquisition of the Galveston Bay Refinery 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
		March 31,
	(In millions)	2014			2013
	Segment income from operations	$	492		$	1,223
	Items not allocated to segments:
	Corporate and other unallocated items(a)(b)	(67		)	(67		)
	Pension settlement expenses(c)	(64		)	—
	Net interest and other financial income (costs)	(46		)	(48		)
	Income before income taxes	$	315		$	1,108
	(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 costs attributable to MPLX are included in the Pipeline Transportation segment. These expenses are not allocated to the Refining & Marketing and Speedway segments.
	(c)	See Note 18.
	The following reconciles segment capital expenditures and investments to total capital expenditures:
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Segment capital expenditures and investments	$	340		$	1,546
	Less: Investments in equity method investees	123			5
	Plus: Items not allocated to segments:
	Capital expenditures not allocated to segments	25			24
	Capitalized interest	6			4
	Total capital expenditures(a)(b)	$	248		$	1,569
	(a)	Capital expenditures include changes in capital accruals.
	(b)	See Note 16 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
		March 31,
	(In millions)	2014			2013
	Customer revenues (as reported above)	$	23,285		$	23,336
	Corporate and other unallocated items	—			(6		)
Sales and other operating revenues (including consumer excise taxes)	$	23,285		$	23,330

Other_Items

Other Items	3 Months Ended
	Mar. 31, 2014
Other Income and Expenses [Abstract]	'
Other Items	'
	Other Items
	Net interest and other financial income (costs) was:
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Interest:
	Interest income	$	2		$	2
	Interest expense	(49		)	(48		)
	Interest capitalized	6			4
	Total net interest	(41		)	(42		)
	Other:
	Net foreign currency losses	—			(1		)
	Bank service and other fees	(5		)	(5		)
	Total other	(5		)	(6		)
	Net interest and other financial income (costs)	$	(46	)	$	(48	)

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The combined federal, state and foreign income tax rate was 34 percent for both the three months ended March 31, 2014 and 2013. The effective tax rate for the three months ended March 31, 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.
	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 March 31, 2014. Pursuant to our tax sharing agreement with Marathon Oil Corporation ("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 20 for indemnification information.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	(In millions)	March 31,		December 31,
		2014		2013
	Crude oil and refinery feedstocks	$	2,734	$	1,797
	Refined products	2,540		2,367
	Materials and supplies	333		425
	Merchandise	82		100
	Total (at cost)	$	5,689	$	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 three months ended March 31, 2014 and 2013.

Property_Plant_and_Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2014
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	Property, Plant and Equipment
	(In millions)	March 31,		December 31,
		2014		2013
	Refining & Marketing	$	17,117	$	16,982
	Speedway	2,374		2,344
	Pipeline Transportation	1,926		1,921
	Corporate and Other	570		546
	Total	21,987		21,793
	Less accumulated depreciation	8,133		7,872
	Property, plant and equipment, net	$	13,854	$	13,921

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 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 March 31, 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.
		March 31, 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	$	41	$	—	$	—	$	(39	)	$	2	$	82
	Other assets	2		—		—		N/A			2		—
	Total assets at fair value	$	43	$	—	$	—	$	(39	)	$	4	$	82
	Commodity derivative instruments, liabilities	$	81	$	—	$	—	$	(81	)	$	—	$	—
	Contingent consideration, liability(c)	—		—		639		N/A			639		—
	Total liabilities at fair value	$	81	$	—	$	639	$	(81	)	$	639	$	—
		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 March 31, 2014 and December 31, 2013, cash collateral of $42 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 $178 million and $159 million classified as current at March 31, 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 March 31, 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 $13 to $18 per barrel; and (3) a range of risk-adjusted discount rates from 5 percent to 10 percent. An increase or decrease in crack spread forecasts or refinery throughput volume expectations will 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 thresholds. An increase or decrease in the discount rate will 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
		March 31,
	(In millions)	2014		2013
	Beginning balance	$	625	$	—
	Contingent consideration agreement	—		600
	Total realized and unrealized losses included in net income	14		—
	Ending balance	$	639	$	600
	We did not hold any Level 3 derivative instruments during the three months ended March 31, 2014 and 2013. See Note 14 for the income statement impacts of our derivative instruments. There was an unrealized loss of $14 million related to the contingent consideration agreement for the three months ended March 31, 2014.
	Fair Values – Reported
	The following table summarizes financial instruments on the basis of their nature, characteristics and risk at March 31, 2014 and December 31, 2013, excluding the derivative financial instruments and contingent consideration reported above.
		March 31, 2014				December 31, 2013
	(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
	Financial assets:
	Investments	$	39	$	13	$	336	$	14
	Other	30		28		31		30
	Total financial assets	$	69	$	41	$	367	$	44
	Financial liabilities:
	Long-term debt(a)	$	3,670	$	3,270	$	3,306	$	3,001
	Deferred credits and other liabilities	21		21		21		21
	Total financial liabilities	$	3,691	$	3,291	$	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	3 Months Ended
	Mar. 31, 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 13. 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 March 31, 2014 and December 31, 2013:
		March 31, 2014
	(In millions)	Asset				Liability			Balance Sheet Location
	Commodity derivatives	$	41			$	81		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 March 31, 2014.
		Position		Total Barrels (In thousands)
	Crude oil(a)
	Exchange-traded	Long		9,640
	Exchange-traded	Short		(35,375	)
	Refined Products(a)
	Exchange-traded	Long		2,317
	Exchange-traded	Short		(3,658	)
	(a)	100 percent of these contracts expire in the second quarter of 2014.
	The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income:
		Gain (Loss)
	(In millions)	Three Months Ended March 31,
	Income Statement Location	2014				2013
	Sales and other operating revenues	$	10			$	1
	Cost of revenues	(61		)		(60		)
	Total	$	(51	)		$	(59	)

Debt

Debt	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	Our outstanding borrowings at March 31, 2014 and December 31, 2013 consisted of the following:
	(In millions)	March 31,			December 31,
		2014			2013
	Marathon Petroleum Corporation:
	Revolving credit agreement due 2017	$	—		$	—
	3.500% senior notes due March 1, 2016	750			750
	5.125% senior notes due March 1, 2021	1,000			1,000
	6.500% senior notes due March 1, 2041	1,250			1,250
	Consolidated subsidiaries:
	Capital lease obligations due 2014-2028	389			395
	MPLX Operations LLC revolving credit agreement due 2017	270			—
	Trade receivables securitization facility due 2016	—			—
	Total	3,659			3,395
	Unamortized discount	(10		)	(10		)
	Fair value adjustments(a)	10			11
	Amounts due within one year	(24		)	(23		)
	Total long-term debt due after one year	$	3,635		$	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 March 31, 2014. During the three months ended March 31, 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. The borrowings were used to fund MPLX's acquisition of an additional interest in Pipe Line Holdings. At March 31, 2014, MPLX had $270 million of borrowings and no letters of credit outstanding under the MPLX Credit Agreement, resulting in total unused loan availability of $230 million, or 46 percent of the borrowing capacity. The MPLX Credit Agreement is scheduled to mature on October 31, 2017.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
	Supplemental Cash Flow Information
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Net cash provided by operating activities included:
	Interest paid (net of amounts capitalized)	$	80		$	83
	Net income taxes paid to (refunded from) taxing authorities	5			(5		)
	Non-cash investing and financing activities:
	Capital lease obligations increase	$	—		$	61
	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:
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Additions to property, plant and equipment	$	267		$	195
	Acquisitions(a)	—			1,377
	Decrease in capital accruals	(19		)	(3		)
	Total capital expenditures	$	248		$	1,569
	(a)	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 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	67			9			—		—		76
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(11		)	(2		)	—		—		(13		)
	– actuarial loss(a)	21			1			—		—		22
	Tax effect	(4		)	1			—		—		(3		)
	Other comprehensive income	73			9			—		—		82
	Balance as of March 31, 2013	$	(359	)	$	(27	)	$	4	$	—	$	(382	)
	(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	(43		)	1			—		—		(42		)
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(12		)	(1		)	—		—		(13		)
	– actuarial loss(a)	13			1			—		—		14
	– settlement loss(a)	64			—			—		—		64
	Tax effect	(24		)	—			—		—		(24		)
	Other comprehensive income (loss)	(2		)	1			—		—		(1		)
	Balance as of March 31, 2014	$	(163	)	$	(49	)	$	4	$	3	$	(205	)
	(a)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 18.

Defined_Benefit_Pension_and_Ot

Defined Benefit Pension and Other Postretirement Plans	3 Months Ended
	Mar. 31, 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 March 31,
		Pension Benefits						Other Benefits
	(In millions)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	23		$	23		$	7		$	6
	Interest cost	20			18			8			7
	Expected return on plan assets	(28		)	(27		)	—			—
	Amortization – prior service credit	(12		)	(11		)	(1		)	(2		)
	– actuarial loss	13			21			1			1
	– net settlement loss	64			—			—			—
	Net periodic benefit cost	$	80		$	24		$	15		$	12
	During the three months ended March 31, 2014, we made no contributions to our funded pension plans. We have no required funding for 2014 but may do so at our discretion. Current benefit payments related to unfunded pension and other postretirement benefit plans were $8 million and $5 million, respectively, during the three months ended March 31, 2014.
	During the three months ended March 31, 2014, we determined that lump sum payments to employees retiring in 2014 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 three months ended March 31, 2014, we recorded pension settlement expenses of $64 million related to our cumulative lump sum payments made during the first three months of 2014.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 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 three months ended March 31, 2014:
		Number of Shares(a)		Weighted Average Exercise Price
	Outstanding at December 31, 2013	5,147,837		$	40.08
	Granted	327,100		83.37
	Exercised	(455,999	)	30.65
	Forfeited, canceled or expired	(19,293	)	50.05
	Outstanding at March 31, 2014	4,999,645		43.73
	(a)	Includes an immaterial number of stock appreciation rights.
	The grant date fair value of stock option awards granted during the three months ended March 31, 2014 was $24.87 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. The assumption for expected volatility of our stock price was refined for the three months ended March 31, 2014 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 three months ended March 31, 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	51,594		83.45		5,939	89.96
	RS's Vested/RSU's Issued	(117,980	)	54.43		—	—
	Forfeited	(14,840	)	64.31		—	—
	Outstanding at March 31, 2014	542,896		64.6		391,018	34.81
	Performance Unit Awards
	The following table presents a summary of the activity for performance unit awards to be settled in shares for the three months ended March 31, 2014:
		Number of Units
	Outstanding at December 31, 2013	3,822,500
	Granted	2,033,700
	Settled	—
	Canceled	—
	Outstanding at March 31, 2014	5,856,200
	The performance unit awards granted in 2014 have a grant date fair value of $1.02 per unit, as calculated using a Monte Carlo valuation model.
	MPLX Awards
	During the three months ended March 31, 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	3 Months Ended
	Mar. 31, 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. 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 both March 31, 2014 and December 31, 2013, accrued liabilities for remediation totaled $123 million. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties if any that may be imposed. Receivables for recoverable costs from certain states, under programs to assist companies in clean-up efforts related to underground storage tanks at presently or formerly owned or operated retail marketing sites, were $50 million and $51 million at March 31, 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 March 31, 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 $41 million as of March 31, 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 March 31, 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 March 31, 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 10, 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 March 31, 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 March 31, 2014, our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $1.8 billion, which includes $700 million of contingent consideration associated with the acquisition of the Galveston Bay Refinery and Related Assets and $854 million for contributions to North Dakota Pipeline. See Notes 4 and 13 for additional information on the contingent consideration. See Note 4 for additional information on our investment in North Dakota Pipeline.

Subsequent_Event_Subsequent_Ev

Subsequent Event Subsequent Event	3 Months Ended
	Mar. 31, 2014
Subsequent Event [Abstract]	'
Subsequent Events	'
	Subsequent Event
	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.

Supplementary_Statistics

Supplementary Statistics	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Supplementary Statistics	'
	Supplementary Statistics (Unaudited)
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Income from Operations by segment
	Refining & Marketing	$	362		$	1,105
	Speedway	58			67
	Pipeline Transportation(a)	72			51
	Items not allocated to segments:
	Corporate and other unallocated items(a)	(67		)	(67		)
	Pension settlement expenses	(64		)	—
	Income from operations	$	361		$	1,156
	Capital Expenditures and Investments(b)(c)
	Refining & Marketing	$	178		$	1,420
	Speedway	32			36
	Pipeline Transportation	130			90
	Corporate and Other(d)	31			28
	Total	$	371		$	1,574
	(a)	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These expenses are not allocated to the Refining & Marketing and Speedway segments.
	(b)	Capital expenditures include changes in capital accruals.
	(c)	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4 to the unaudited consolidated financial statements.
	(d)	Includes capitalized interest $6 million and $4 million for the three months ended March 31, 2014 and 2013, respectively.
	Supplementary Statistics (Unaudited)
		Three Months Ended
		March 31,
		2014			2013
	MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)(a)(b)	1,964			1,895
	Refining & Marketing Operating Statistics(b)
	Refining & Marketing Refined Product Sales Volume (thousands of barrels per day)(c)	1,951			1,880
	Refining & Marketing Gross Margin (dollars per barrel)(d)	$	14.46		$	15.29
	Crude Oil Capacity Utilization percent(e)	85			93
	Refinery Throughputs (thousands of barrels per day):(f)
	Crude oil refined	1,450			1,433
	Other charge and blendstocks	200			238
	Total	1,650			1,671
	Sour Crude Oil Throughput percent	49			54
	WTI-Priced Crude Oil Throughput percent	21			22
	Refined Product Yields (thousands of barrels per day):(f)
	Gasoline	837			889
	Distillates	514			523
	Propane	34			32
	Feedstocks and special products	220			184
	Heavy fuel oil	30			30
	Asphalt	43			46
	Total	1,678			1,704
	Refinery Direct Operating Costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	3.15		$	1.15
	Depreciation and amortization	1.55			1.42
	Other manufacturing(h)	5.95			3.81
	Total	$	10.65		$	6.38
	Refining & Marketing Operating Statistics By Region
	Gulf Coast:(b)
	Refinery Throughputs (thousands of barrels per day):(i)
	Crude oil refined	860			837
	Other charge and blendstocks	211			211
	Total	1,071			1,048
	Sour Crude Oil Throughput percent	60			68
	WTI-Priced Crude Oil Throughput percent	3			6
	Refined Product Yields (thousands of barrels per day):(i)
	Gasoline	489			531
	Distillates	319			322
	Propane	21			19
	Feedstocks and special products	245			179
Heavy fuel oil	15			18
Asphalt	7			6
Total	1,096			1,075
Refinery Direct Operating Costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	3.83		$	0.87
Depreciation and amortization	1.25			1.13
Other manufacturing(h)	5.87			3.29
Total	$	10.95		$	5.29
Supplementary Statistics (Unaudited)
	Three Months Ended
	March 31,
	2014			2013
Refining & Marketing Operating Statistics By Region
Midwest:
Refinery Throughputs (thousands of barrels per day):(i)
Crude oil refined	590			596
Other charge and blendstocks	48			56
Total	638			652
Sour Crude Oil Throughput percent	34			35
WTI-Priced Crude Oil Throughput percent	47			45
Refined Product Yields (thousands of barrels per day):(i)
Gasoline	348			358
Distillates	195			201
Propane	13			13
Feedstocks and special products	33			34
Heavy fuel oil	16			12
Asphalt	36			40
Total	641			658
Refinery Direct Operating Costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	1.71		$	1.56
Depreciation and amortization	1.91			1.82
Other manufacturing(h)	5.54			4.47
Total	$	9.16		$	7.85
Speedway Operating Statistics
Convenience stores at period-end	1,482			1,463
Gasoline and distillate sales (millions of gallons)	773			745
Gasoline and distillate gross margin (dollars per gallon)(j)	$	0.1156		$	0.1301
Merchandise sales (in millions)	$	722		$	711
Merchandise gross margin (in millions)	$	192		$	184
Same store gasoline sales volume (period over period)	(0.7		)%	0.7		%
Same store merchandise sales (period over period)(k)	5.3		%	0.8		%
Pipeline Transportation Operating Statistics
Pipeline Throughputs (thousands of barrels per day):(l)
Crude oil pipelines	1,144			1,272
Refined products pipelines	819			917
Total	1,963			2,189
(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 59 mbpd and 29 mbpd for the three months ended March 31, 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)	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.
(k)	Excludes cigarettes.
(l)	On owned common-carrier pipelines, excluding equity method investments.

Description_of_the_Business_an1

Description of the Business and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 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 (“US 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. The assumption for expected volatility of our stock price was refined for the three months ended March 31, 2014 to reflect a weighting of 50 percent of MPC’s common stock implied volatility and 50 percent of MPC's common stock historical volatility.

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 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
		March 31,
	(In millions)	2014		2013
	Other equity method investees	$	2	$	2
Purchases From Related Parties	'
	Purchases from related parties were as follows:
		Three Months Ended
		March 31,
	(In millions)	2014		2013
	Centennial	$	9	$	—
	Explorer	13		—
	LOCAP	5		4
	LOOP	53		10
	TAAE	16		—
	TACE	27		26
	TAME	34		30
	Other equity method investees	2		2
	Total	$	159	$	72
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)	March 31,		December 31,
		2014		2013
	Centennial	$	—	$	1
	Explorer	5		—
	TAME	—		1
	Total	$	5	$	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)	March 31,		December 31,
		2014		2013
	Explorer	$	4	$	—
	LOCAP	2		2
	LOOP	4		3
	TAAE	2		2
	TACE	4		4
	TAME	7		5
	Total	$	23	$	16

Income_per_Common_Share_Tables

Income per Common Share (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Summary of Earnings Per Common Share	'
		Three Months Ended
		March 31,
	(In millions, except per share data)	2014		2013
	Basic earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	199	$	725
	Income allocated to participating securities	—		1
	Income available to common stockholders - basic	$	199	$	724
	Weighted average common shares outstanding	293		331
	Basic earnings per share	$	0.68	$	2.19
	Diluted earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	199	$	725
	Income allocated to participating securities	—		1
	Income available to common stockholders - diluted	$	199	$	724
	Weighted average common shares outstanding	293		331
	Effect of dilutive securities	2		2
	Weighted average common shares, including dilutive effect	295		333
	Diluted earnings per share	$	0.67	$	2.17

Equity_Tables

Equity (Tables)	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
Share Repurchases Transacted Through ASR Programs and Open Market Transactions	'
	Total share repurchases were as follows for the three months ended March 31, 2014 and 2013:
		Three Months Ended
		March 31,
	(In millions, except per share data)	2014		2013
	Number of shares repurchased(a)	8		6
	Cash paid for shares repurchased	$	689	$	431
	Effective average cost per delivered share	$	87.6	$	80.95
	(a)	The three months ended March 31, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in the fourth quarter of 2012.

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Income From Operations Attributable To Operating Segments	'
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation		Total
	Three Months Ended March 31, 2014
	Revenues:
	Customer	$	19,810		$	3,458		$	17	$	23,285
	Intersegment(a)	2,233			1			129		2,363
	Segment revenues	$	22,043		$	3,459		$	146	$	25,648
	Segment income from operations(b)	$	362		$	58		$	72	$	492
	Income from equity method investments	24			—			11		35
	Depreciation and amortization(c)	261			28			19		308
	Capital expenditures and investments(d)	178			32			130		340
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation		Total
	Three Months Ended March 31, 2013
	Revenues:
	Customer	$	19,874		$	3,441		$	21	$	23,336
	Intersegment(a)	2,199			1			104		2,304
	Segment revenues	$	22,073		$	3,442		$	125	$	25,640
	Segment income from operations(b)	$	1,105		$	67		$	51	$	1,223
	Income (loss) from equity method investments	(4		)	—			4		—
	Depreciation and amortization(c)	236			27			18		281
	Capital expenditures and investments(d)(e)	1,420			36			90		1,546
	(a)	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.
	(b)	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These 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.
	(e)	The Refining & Marketing and Pipeline Transportation segments include the acquisition of the Galveston Bay Refinery 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
		March 31,
	(In millions)	2014			2013
	Segment income from operations	$	492		$	1,223
	Items not allocated to segments:
	Corporate and other unallocated items(a)(b)	(67		)	(67		)
	Pension settlement expenses(c)	(64		)	—
	Net interest and other financial income (costs)	(46		)	(48		)
	Income before income taxes	$	315		$	1,108
	(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 costs attributable to MPLX are included in the Pipeline Transportation segment. These expenses are not allocated to the Refining & Marketing and Speedway segments.
	(c)	See Note 18.
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
		March 31,
	(In millions)	2014			2013
	Segment capital expenditures and investments	$	340		$	1,546
	Less: Investments in equity method investees	123			5
	Plus: Items not allocated to segments:
	Capital expenditures not allocated to segments	25			24
	Capitalized interest	6			4
	Total capital expenditures(a)(b)	$	248		$	1,569
	(a)	Capital expenditures include changes in capital accruals.
	(b)	See Note 16 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
		March 31,
	(In millions)	2014			2013
	Customer revenues (as reported above)	$	23,285		$	23,336
	Corporate and other unallocated items	—			(6		)
	Sales and other operating revenues (including consumer excise taxes)	$	23,285		$	23,330

Other_Items_Tables

Other Items (Tables)	3 Months Ended
	Mar. 31, 2014
Other Income and Expenses [Abstract]	'
Net Interest And Other Financial Income (Costs)	'
	Net interest and other financial income (costs) was:
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Interest:
	Interest income	$	2		$	2
	Interest expense	(49		)	(48		)
	Interest capitalized	6			4
	Total net interest	(41		)	(42		)
	Other:
	Net foreign currency losses	—			(1		)
	Bank service and other fees	(5		)	(5		)
	Total other	(5		)	(6		)
	Net interest and other financial income (costs)	$	(46	)	$	(48	)

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Summary Of Inventories	'
	(In millions)	March 31,		December 31,
		2014		2013
	Crude oil and refinery feedstocks	$	2,734	$	1,797
	Refined products	2,540		2,367
	Materials and supplies	333		425
	Merchandise	82		100
	Total (at cost)	$	5,689	$	4,689

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2014
Property, Plant and Equipment [Abstract]	'
Summary Of Property, Plant And Equipment	'
	(In millions)	March 31,		December 31,
		2014		2013
	Refining & Marketing	$	17,117	$	16,982
	Speedway	2,374		2,344
	Pipeline Transportation	1,926		1,921
	Corporate and Other	570		546
	Total	21,987		21,793
	Less accumulated depreciation	8,133		7,872
	Property, plant and equipment, net	$	13,854	$	13,921

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 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.
		March 31, 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	$	41	$	—	$	—	$	(39	)	$	2	$	82
	Other assets	2		—		—		N/A			2		—
	Total assets at fair value	$	43	$	—	$	—	$	(39	)	$	4	$	82
	Commodity derivative instruments, liabilities	$	81	$	—	$	—	$	(81	)	$	—	$	—
	Contingent consideration, liability(c)	—		—		639		N/A			639		—
	Total liabilities at fair value	$	81	$	—	$	639	$	(81	)	$	639	$	—
		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 March 31, 2014 and December 31, 2013, cash collateral of $42 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 $178 million and $159 million classified as current at March 31, 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
		March 31,
	(In millions)	2014		2013
	Beginning balance	$	625	$	—
	Contingent consideration agreement	—		600
	Total realized and unrealized losses included in net income	14		—
	Ending balance	$	639	$	600
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 March 31, 2014 and December 31, 2013, excluding the derivative financial instruments and contingent consideration reported above.
		March 31, 2014				December 31, 2013
	(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
	Financial assets:
	Investments	$	39	$	13	$	336	$	14
	Other	30		28		31		30
	Total financial assets	$	69	$	41	$	367	$	44
	Financial liabilities:
	Long-term debt(a)	$	3,670	$	3,270	$	3,306	$	3,001
	Deferred credits and other liabilities	21		21		21		21
	Total financial liabilities	$	3,691	$	3,291	$	3,327	$	3,022
	(a)	Excludes capital leases

Derivatives_Tables

Derivatives (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2014 and December 31, 2013:
		March 31, 2014
	(In millions)	Asset				Liability			Balance Sheet Location
	Commodity derivatives	$	41			$	81		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 March 31, 2014.
		Position		Total Barrels (In thousands)
	Crude oil(a)
	Exchange-traded	Long		9,640
	Exchange-traded	Short		(35,375	)
	Refined Products(a)
	Exchange-traded	Long		2,317
	Exchange-traded	Short		(3,658	)
	(a)	100 percent of these contracts expire in the second 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)
	(In millions)	Three Months Ended March 31,
	Income Statement Location	2014				2013
	Sales and other operating revenues	$	10			$	1
	Cost of revenues	(61		)		(60		)
	Total	$	(51	)		$	(59	)

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Outstanding Borrowings	'
	Our outstanding borrowings at March 31, 2014 and December 31, 2013 consisted of the following:
	(In millions)	March 31,			December 31,
		2014			2013
	Marathon Petroleum Corporation:
	Revolving credit agreement due 2017	$	—		$	—
	3.500% senior notes due March 1, 2016	750			750
	5.125% senior notes due March 1, 2021	1,000			1,000
	6.500% senior notes due March 1, 2041	1,250			1,250
	Consolidated subsidiaries:
	Capital lease obligations due 2014-2028	389			395
	MPLX Operations LLC revolving credit agreement due 2017	270			—
	Trade receivables securitization facility due 2016	—			—
	Total	3,659			3,395
	Unamortized discount	(10		)	(10		)
	Fair value adjustments(a)	10			11
	Amounts due within one year	(24		)	(23		)
	Total long-term debt due after one year	$	3,635		$	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)	3 Months Ended
	Mar. 31, 2014
Supplemental Cash Flow Elements [Abstract]	'
Summary of Supplemental Cash Flow Information	'
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Net cash provided by operating activities included:
	Interest paid (net of amounts capitalized)	$	80		$	83
	Net income taxes paid to (refunded from) taxing authorities	5			(5		)
	Non-cash investing and financing activities:
	Capital lease obligations increase	$	—		$	61
	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:
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Additions to property, plant and equipment	$	267		$	195
	Acquisitions(a)	—			1,377
	Decrease in capital accruals	(19		)	(3		)
	Total capital expenditures	$	248		$	1,569
	(a)	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 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	67			9			—		—		76
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(11		)	(2		)	—		—		(13		)
	– actuarial loss(a)	21			1			—		—		22
	Tax effect	(4		)	1			—		—		(3		)
	Other comprehensive income	73			9			—		—		82
	Balance as of March 31, 2013	$	(359	)	$	(27	)	$	4	$	—	$	(382	)
	(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	(43		)	1			—		—		(42		)
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(12		)	(1		)	—		—		(13		)
	– actuarial loss(a)	13			1			—		—		14
	– settlement loss(a)	64			—			—		—		64
	Tax effect	(24		)	—			—		—		(24		)
	Other comprehensive income (loss)	(2		)	1			—		—		(1		)
	Balance as of March 31, 2014	$	(163	)	$	(49	)	$	4	$	3	$	(205	)
	(a)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 18.

Defined_Benefit_Pension_and_Ot1

Defined Benefit Pension and Other Postretirement Plans (Tables)	3 Months Ended
	Mar. 31, 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 March 31,
		Pension Benefits						Other Benefits
	(In millions)	2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	23		$	23		$	7		$	6
	Interest cost	20			18			8			7
	Expected return on plan assets	(28		)	(27		)	—			—
	Amortization – prior service credit	(12		)	(11		)	(1		)	(2		)
	– actuarial loss	13			21			1			1
	– net settlement loss	64			—			—			—
	Net periodic benefit cost	$	80		$	24		$	15		$	12

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 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 three months ended March 31, 2014:
		Number of Shares(a)		Weighted Average Exercise Price
	Outstanding at December 31, 2013	5,147,837		$	40.08
	Granted	327,100		83.37
	Exercised	(455,999	)	30.65
	Forfeited, canceled or expired	(19,293	)	50.05
	Outstanding at March 31, 2014	4,999,645		43.73
	(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 three months ended March 31, 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	51,594		83.45		5,939	89.96
	RS's Vested/RSU's Issued	(117,980	)	54.43		—	—
	Forfeited	(14,840	)	64.31		—	—
	Outstanding at March 31, 2014	542,896		64.6		391,018	34.81
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 three months ended March 31, 2014:
		Number of Units
	Outstanding at December 31, 2013	3,822,500
	Granted	2,033,700
	Settled	—
	Canceled	—
	Outstanding at March 31, 2014	5,856,200

Supplementary_Statistics_Table

Supplementary Statistics (Tables)	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Supplementary Statistics	'
	Supplementary Statistics (Unaudited)
		Three Months Ended
		March 31,
	(In millions)	2014			2013
	Income from Operations by segment
	Refining & Marketing	$	362		$	1,105
	Speedway	58			67
	Pipeline Transportation(a)	72			51
	Items not allocated to segments:
	Corporate and other unallocated items(a)	(67		)	(67		)
	Pension settlement expenses	(64		)	—
	Income from operations	$	361		$	1,156
	Capital Expenditures and Investments(b)(c)
	Refining & Marketing	$	178		$	1,420
	Speedway	32			36
	Pipeline Transportation	130			90
	Corporate and Other(d)	31			28
	Total	$	371		$	1,574
	(a)	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These expenses are not allocated to the Refining & Marketing and Speedway segments.
	(b)	Capital expenditures include changes in capital accruals.
	(c)	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4 to the unaudited consolidated financial statements.
	(d)	Includes capitalized interest $6 million and $4 million for the three months ended March 31, 2014 and 2013, respectively.
Operating Statistics	'
	Supplementary Statistics (Unaudited)
		Three Months Ended
		March 31,
		2014			2013
	MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)(a)(b)	1,964			1,895
	Refining & Marketing Operating Statistics(b)
	Refining & Marketing Refined Product Sales Volume (thousands of barrels per day)(c)	1,951			1,880
	Refining & Marketing Gross Margin (dollars per barrel)(d)	$	14.46		$	15.29
	Crude Oil Capacity Utilization percent(e)	85			93
	Refinery Throughputs (thousands of barrels per day):(f)
	Crude oil refined	1,450			1,433
	Other charge and blendstocks	200			238
	Total	1,650			1,671
	Sour Crude Oil Throughput percent	49			54
	WTI-Priced Crude Oil Throughput percent	21			22
	Refined Product Yields (thousands of barrels per day):(f)
	Gasoline	837			889
	Distillates	514			523
	Propane	34			32
	Feedstocks and special products	220			184
	Heavy fuel oil	30			30
	Asphalt	43			46
	Total	1,678			1,704
	Refinery Direct Operating Costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	3.15		$	1.15
	Depreciation and amortization	1.55			1.42
	Other manufacturing(h)	5.95			3.81
	Total	$	10.65		$	6.38
	Refining & Marketing Operating Statistics By Region
	Gulf Coast:(b)
	Refinery Throughputs (thousands of barrels per day):(i)
	Crude oil refined	860			837
	Other charge and blendstocks	211			211
	Total	1,071			1,048
	Sour Crude Oil Throughput percent	60			68
	WTI-Priced Crude Oil Throughput percent	3			6
	Refined Product Yields (thousands of barrels per day):(i)
	Gasoline	489			531
	Distillates	319			322
	Propane	21			19
	Feedstocks and special products	245			179
	Heavy fuel oil	15			18
	Asphalt	7			6
	Total	1,096			1,075
	Refinery Direct Operating Costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	3.83		$	0.87
	Depreciation and amortization	1.25			1.13
	Other manufacturing(h)	5.87			3.29
	Total	$	10.95		$	5.29
	Supplementary Statistics (Unaudited)
		Three Months Ended
		March 31,
		2014			2013
	Refining & Marketing Operating Statistics By Region
	Midwest:
	Refinery Throughputs (thousands of barrels per day):(i)
	Crude oil refined	590			596
	Other charge and blendstocks	48			56
	Total	638			652
	Sour Crude Oil Throughput percent	34			35
	WTI-Priced Crude Oil Throughput percent	47			45
	Refined Product Yields (thousands of barrels per day):(i)
	Gasoline	348			358
Distillates	195			201
Propane	13			13
Feedstocks and special products	33			34
Heavy fuel oil	16			12
Asphalt	36			40
Total	641			658
Refinery Direct Operating Costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	1.71		$	1.56
Depreciation and amortization	1.91			1.82
Other manufacturing(h)	5.54			4.47
Total	$	9.16		$	7.85
Speedway Operating Statistics
Convenience stores at period-end	1,482			1,463
Gasoline and distillate sales (millions of gallons)	773			745
Gasoline and distillate gross margin (dollars per gallon)(j)	$	0.1156		$	0.1301
Merchandise sales (in millions)	$	722		$	711
Merchandise gross margin (in millions)	$	192		$	184
Same store gasoline sales volume (period over period)	(0.7		)%	0.7		%
Same store merchandise sales (period over period)(k)	5.3		%	0.8		%
Pipeline Transportation Operating Statistics
Pipeline Throughputs (thousands of barrels per day):(l)
Crude oil pipelines	1,144			1,272
Refined products pipelines	819			917
Total	1,963			2,189
(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 59 mbpd and 29 mbpd for the three months ended March 31, 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)	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.
(k)	Excludes cigarettes.
(l)	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 $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 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 $)	3 Months Ended		0 Months Ended					0 Months Ended			6 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 01, 2014	1-May-13	Mar. 01, 2014	Mar. 01, 2014	Oct. 31, 2012	Mar. 01, 2014	Mar. 31, 2014	Mar. 31, 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%
Ownership interest in assets owned by company in affiliate	'	'	'	'	'	'	100.00%	'	'	'	'
Additional interest sold	'	'	13.00%	5.00%	'	'	'	'	'	'	'
Proceeds from sale of ownership interest	'	'	$310	$100	'	'	'	'	'	'	'
Cash paid for acquisition	$0	$1,493	'	'	$270	$40	'	'	'	'	'

Acquisitions_and_Investments_A

Acquisitions and Investments (Acquisition of Refinery and Related Logistics and Marketing Assets) (Detail) (USD $)	3 Months Ended		1 Months Ended		3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Feb. 01, 2013	Mar. 31, 2014	Jun. 30, 2014
			Galveston Bay Refinery and Related Assets	Galveston Bay Refinery and Related Assets	Scenario, Forecast
			site		Galveston Bay Refinery and Related Assets
			Pipeline
			Terminal
			BPCD
			BPD
			MW
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	$0	$1,493,000,000	$1,490,000,000	'	$178,000,000
Inventories	'	'	935,000,000	'	'
Total cumulative payment capped over six-year period	'	'	$700,000,000	$700,000,000	'
Term of payment of maximum earnout provision payable to the company, years	'	'	'6 years	'	'

Acquisitions_and_Investments_A1

Acquisitions and Investments Acquisition and Investments (Schedule of Acquisition Related Pro Forma Financial Information) (Details) (Galveston Bay Refinery and Related Assets, USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013
Galveston Bay Refinery and Related Assets	'
Business Acquisition [Line Items]	'
Sales and other operating revenues (including consumer excise taxes)	$25,296
Net income attributable to MPC	$780
Net income attributable to MPC per share - basic	$2.36
Net income attributable to MPC per share - diluted	$2.34

Acquisitions_and_Investments_A2

Acquisitions and Investments Acquisitions and Investments (Acquisitions of Convenience Stores) (Details) (Speedway, USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
	Store
Speedway	'
Business Acquisition [Line Items]	'
Number of convenience stores acquired	9
Goodwill acquired during period	$8

Acquisitions_and_Investments_A3

Acquisitions and Investments Acquisitions and Investments (Investments in Ethanol Companies) (Details) (USD $)	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Oct. 02, 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			Companies	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_A4

Acquisitions and Investments Acquisitions and Investments (Investments in Pipeline Companies) (Details) (USD $)	3 Months Ended	6 Months Ended			0 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2014	Jan. 02, 2016	Jan. 02, 2016	Mar. 04, 2014	Mar. 31, 2014
	North Dakota Pipeline	North Dakota Pipeline	North Dakota Pipeline Class A Units	North Dakota Pipeline Class A Units	Explorer Pipeline	Explorer Pipeline
			Scenario, Forecast	Scenario, Forecast
				Maximum
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'
Cash paid to acquire equity method investments	$37	$61	'	'	$77	'
Equity method investments, ownership percentage	37.50%	37.50%	27.00%	30.00%	'	25.00%
Ownership percentage acquired	'	'	'	'	7.00%	'

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Detail) (USD $)	Mar. 31, 2014	Oct. 02, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014
In Millions, unless otherwise specified	TAAE	TAAE	TACE	TAME	Centennial	Centennial	Explorer	LOCAP	LOOP
Related Party Transaction [Line Items]	'	'	'	'	'	'	'	'	'
Equity method investments, ownership percentage	43.00%	43.00%	60.00%	67.00%	50.00%	'	25.00%	59.00%	51.00%
Long-term receivable from related party	'	'	'	'	$2	$2	'	'	'

Related_Party_Transactions_Sal

Related Party Transactions - Sales to Related Parties (Detail) (Other equity method investees, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Other equity method investees	'	'
Related Party Transaction [Line Items]	'	'
Sales to related parties	$2	$2

Related_Party_Transactions_Pur

Related Party Transactions - Purchases from Related Parties (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Related Party Transaction [Line Items]	'	'
Purchases from related parties	$159	$72
Centennial	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	9	0
Explorer	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	13	0
LOCAP	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	5	4
LOOP	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	53	10
TAAE	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	16	0
TACE	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	27	26
TAME	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	34	30
Other equity method investees	'	'
Related Party Transaction [Line Items]	'	'
Purchases from related parties	$2	$2

Related_Party_Transactions_Rel

Related Party Transactions Related Party Transactions - Receivables From Related Parties (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	$5	$2
Centennial	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	0	1
Explorer	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	5	0
TAME	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	$0	$1

Related_Party_Transactions_Pay

Related Party Transactions - Payables To Related Parties (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Payables to related parties	$23	$16
Explorer	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	4	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	2	2
TACE	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	4	4
TAME	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	$7	$5

Income_Per_Common_Share_Additi

Income Per Common Share - Additional Information (Detail) (Stock Based Compensation Award)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Stock Based Compensation Award	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Excluded from diluted share calculation	1	1

Income_Per_Common_Share_Summar

Income Per Common Share - Summary of Earnings Per Common Share (Detail) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Basic earnings per share:	'	'
Net income attributable to MPC	$199	$725
Income allocated to participating securities	0	1
Income available to common stockholders - basic	199	724
Weighted average common shares outstanding (in shares)	293	331
Basic (in USD per share)	$0.68	$2.19
Diluted earnings per share:	'	'
Net income attributable to MPC	199	725
Income allocated to participating securities	0	1
Income available to common stockholders - diluted	$199	$724
Weighted average common shares outstanding (in shares)	293	331
Effect of dilutive securities (in shares)	2	2
Weighted average common shares, including dilutive effect (in shares)	295	333
Diluted (in USD per share)	$0.67	$2.17

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended			27 Months Ended	1 Months Ended	3 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Sep. 26, 2013	Mar. 31, 2014	Mar. 31, 2013		Mar. 31, 2014	Apr. 30, 2014	Mar. 31, 2013
						Scenario, Forecast	Accelerated Share Repurchase Program November 2012
Stockholders Equity Note [Line Items]	'	'	'		'	'	'
Stock repurchase plan authorized amount	'	'	'		$6,000,000,000	'	'
Cash paid for shares repurchased	'	689,000,000	431,000,000		4,830,000,000	12,000,000	'
Stock repurchase plan remaining authorized amount	'	'	'		$1,170,000,000	'	'
Ending date of share repurchase authorization	'September 2015	'	'		'	'	'
Number of shares repurchased	'	8	6	[1]	73	'	1
Effective average cost per delivered share	'	$87.60	$80.95		$66.19	'	'
[1]	The three months ended March 31, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in the fourth quarter of 2012.

Equity_Share_Repurchases_Trans

Equity - Share Repurchases Transacted Through ASR Programs and Open Market Transactions (Detail) (USD $)	3 Months Ended			27 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013		Mar. 31, 2014
Stockholders Equity [Line Items]	'	'		'
Number of shares repurchased	8	6	[1]	73
Cash paid for shares repurchased	$689	$431		$4,830
Effective average cost per delivered share	$87.60	$80.95		$66.19
Accelerated Share Repurchase Program November 2012	'	'		'
Stockholders Equity [Line Items]	'	'		'
Number of shares repurchased	'	1		'
[1]	The three months ended March 31, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in the fourth quarter of 2012.

Segment_Information_Additional

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 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
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Segment Reporting Information [Line Items]	'		'
Revenues	$23,285		$23,330
Income from operations	361		1,156
Income (loss) from equity method investments	35		0
Depreciation and amortization	320		287
Capital expenditures and investments	371	[1],[2],[3]	1,574	[1],[2],[3]
Refining & Marketing	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	19,810		19,874
Speedway	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	3,458		3,441
Pipeline Transportation	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	17		21
Reportable Segment	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	23,285		23,336
Intersegment Eliminations	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	-2,363	[4]	-2,304	[4]
Intersegment Eliminations | Refining & Marketing	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	-2,233	[4]	-2,199	[4]
Intersegment Eliminations | Speedway	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	-1	[4]	-1	[4]
Intersegment Eliminations | Pipeline Transportation	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	-129	[4]	-104	[4]
Operating Segments	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	25,648		25,640
Income from operations	492	[5]	1,223	[5]
Income (loss) from equity method investments	35		0
Depreciation and amortization	308	[6]	281	[6]
Capital expenditures and investments	340	[1]	1,546	[1],[7]
Operating Segments | Refining & Marketing	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	22,043		22,073
Income from operations	362		1,105
Income (loss) from equity method investments	24		-4
Depreciation and amortization	261	[6]	236	[6]
Capital expenditures and investments	178	[1]	1,420	[1],[7]
Operating Segments | Speedway	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	3,459		3,442
Income from operations	58		67
Income (loss) from equity method investments	0		0
Depreciation and amortization	28	[6]	27	[6]
Capital expenditures and investments	32	[1]	36	[1],[7]
Operating Segments | Pipeline Transportation	'		'
Segment Reporting Information [Line Items]	'		'
Revenues	146		125
Income from operations	72	[5]	51	[5]
Income (loss) from equity method investments	11		4
Depreciation and amortization	19	[6]	18	[6]
Capital expenditures and investments	$130	[1]	$90	[1],[7]
[1]	Capital expenditures include changes in capital accruals.
[2]	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4 to the unaudited consolidated financial statements.
[3]	Includes capitalized interest $6 million and $4 million for the three months ended March 31, 2014 and 2013, respectively.
[4]	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties
[5]	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These 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 Refining & Marketing and Pipeline Transportation segments include 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
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'
Income from operations	$361		$1,156
Net interest and other financial income (costs)	-46		-48
Income before income taxes	315		1,108
Operating Segments	'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'
Income from operations	492	[1]	1,223	[1]
Corporate and Other	'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'
Income from operations	-67	[1],[2]	-67	[1],[2]
Segment Reconciling Items	'		'
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'		'
Pension settlement expenses	($64)	[3]	$0
[1]	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These 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]	See Note 18.

Segment_Information_Reconcilia1

Segment Information - Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'
Capital expenditures and investments	$371	[1],[2],[3]	$1,574	[1],[2],[3]
Plus: Items not allocated to segments:	'		'
Total capital expenditures	248	[1],[4]	1,569	[1],[4]
Operating Segments	'		'
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'
Capital expenditures and investments	340	[1]	1,546	[1],[5]
Less: Investments in equity method investees	123		5
Corporate and Other	'		'
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'
Capital expenditures and investments	31	[1],[3]	28	[1],[3]
Plus: Items not allocated to segments:	'		'
Capital expenditures not allocated to segments	25		24
Capitalized interest	$6		$4
[1]	Capital expenditures include changes in capital accruals.
[2]	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4 to the unaudited consolidated financial statements.
[3]	Includes capitalized interest $6 million and $4 million for the three months ended March 31, 2014 and 2013, respectively.
[4]	See Note 16 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
[5]	The Refining & Marketing and Pipeline Transportation segments include 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
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'
Sales and other operating revenues (including consumer excise taxes)	$23,285	$23,330
Corporate and Other	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'
Sales and other operating revenues (including consumer excise taxes)	0	-6
Reportable Segment	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'
Sales and other operating revenues (including consumer excise taxes)	$23,285	$23,336

Other_Items_Net_Interest_And_O

Other Items - Net Interest And Other Financial Income (Costs) (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Interest:	'	'
Interest income	$2	$2
Interest expense	-49	-48
Interest capitalized	6	4
Total net interest	-41	-42
Other:	'	'
Net foreign currency losses	0	-1
Bank service and other fees	-5	-5
Total other	-5	-6
Net interest and other financial income (costs)	($46)	($48)

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]	'	'
Combined federal, state and foreign income tax rate	34.00%	34.00%
Statutory rate applied to income before income taxes	35.00%	'
Unrecognized benefits	$16	'

Inventories_Summary_Of_Invento

Inventories - Summary Of Inventories (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Crude oil and refinery feedstocks	$2,734	$1,797
Refined products	2,540	2,367
Materials and supplies	333	425
Merchandise	82	100
Total (at cost)	$5,689	$4,689

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 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 $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	$21,987	$21,793
Less accumulated depreciation	8,133	7,872
Net property, plant and equipment	13,854	13,921
Operating Segments | Refining & Marketing	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	17,117	16,982
Operating Segments | Speedway	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	2,374	2,344
Operating Segments | Pipeline Transportation	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	1,926	1,921
Corporate and Other	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	$570	$546

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash collateral	$42		$32
Liabilities, current	178		159
Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	2	[1]	0	[1]
Other assets	2		2
Total assets at fair value	4		2
Commodity derivative instruments, liabilities	0	[1]	0	[1]
Contingent consideration, liability	639	[2]	625	[2]
Total liabilities at fair value	639		625
Level 1 | Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	41		21
Other assets	2		2
Total assets at fair value	43		23
Commodity derivative instruments, liabilities	81		53
Contingent consideration, liability	0		0
Total liabilities at fair value	81		53
Level 2 | Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	0		0
Other assets	0		0
Total assets at fair value	0		0
Commodity derivative instruments, liabilities	0		0
Contingent consideration, liability	0		0
Total liabilities at fair value	0		0
Level 3 | Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	0		0
Other assets	0		0
Total assets at fair value	0		0
Commodity derivative instruments, liabilities	0		0
Contingent consideration, liability	639	[2]	625	[2]
Total liabilities at fair value	639		625
Netting and Collateral | Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	-39	[3]	-21	[3]
Total assets at fair value	-39	[3]	-21	[3]
Commodity derivative instruments, liabilities	-81	[3]	-53	[3]
Total liabilities at fair value	-81	[3]	-53	[3]
Collateral Pledged Not Offset | Fair Value, Measurements, Recurring	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	82		61
Other assets	0		0
Total assets at fair value	82		61
Commodity derivative instruments, liabilities	0		0
Contingent consideration, liability	0		0
Total liabilities at fair value	$0		$0
[1]	We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.
[2]	Includes $178 million and $159 million classified as current at March 31, 2014 and December 31, 2013, respectively.
[3]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of March 31, 2014 and December 31, 2013, cash collateral of $42 million and $32 million, respectively, was netted with mark-to-market derivative liabilities.

Fair_Value_Measurements_Narrat

Fair Value Measurements - Narrative (Detail) (USD $)	3 Months Ended						3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Feb. 01, 2013	Mar. 31, 2014	Mar. 31, 2014
	Fair Value, Measurements, Recurring	Fair Value, Measurements, Recurring	Fair Value, Measurements, Recurring	Fair Value, Measurements, Recurring	Galveston Bay Refinery and Related Assets	Galveston Bay Refinery and Related Assets	Galveston Bay Refinery and Related Assets	Galveston Bay Refinery and Related Assets
	Derivative	Derivative	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	700,000,000	'	'
Range of internal and external crack spread forecast per barrel	'	'	'	'	'	'	13	18
Discount rate	'	'	'	'	'	'	5.00%	10.00%
Unrealized losses included in net income	$0	$0	$14,000,000	$0	'	'	'	'

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
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Beginning balance	$625	$0
Contingent consideration agreement	0	600
Total realized and unrealized losses included in net income	14	0
Ending balance	$639	$600

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Instruments at Fair Value, Excluding Derivative Financial Instruments and Contingent Consideration (Detail) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value	'		'
Financial assets:	'		'
Investments	$39		$336
Other	30		31
Total financial assets	69		367
Financial liabilities:	'		'
Long-term debt	3,670	[1]	3,306	[1]
Deferred credits and other liabilities	21		21
Total financial liabilities	3,691		3,327
Carrying Value	'		'
Financial assets:	'		'
Investments	13		14
Other	28		30
Total financial assets	41		44
Financial liabilities:	'		'
Long-term debt	3,270	[1]	3,001	[1]
Deferred credits and other liabilities	21		21
Total financial liabilities	$3,291		$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 $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Commodity derivatives | Other current assets	'	'
Derivatives, Fair Value [Line Items]	'	'
Asset	$41	$21
Liability	$81	$53

Derivatives_Open_Commodity_Der

Derivatives - Open Commodity Derivative Contracts (Detail)	3 Months Ended
	Mar. 31, 2014
Crude Oil Exchange-Traded	'
Derivative [Line Items]	'
Percentage of derivative contracts expiring in the period	100.00%
Derivative contract expiration date	30-Jun-14
Crude Oil Exchange-Traded | Long	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	9,640,000	[1]
Crude Oil Exchange-Traded | Short	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	35,375,000	[1]
Refined Products Exchange-Traded	'
Derivative [Line Items]	'
Percentage of derivative contracts expiring in the period	100.00%
Derivative contract expiration date	30-Jun-14
Refined Products Exchange-Traded | Long	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	2,317,000	[1]
Refined Products Exchange-Traded | Short	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	3,658,000	[1]
[1]	100 percent of these contracts expire in the second quarter of 2014.

Derivatives_Effect_of_Commodit

Derivatives - Effect of Commodity Derivative Instruments in Statements of Income (Detail) (Commodity derivatives, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss)	($51)	($59)
Sales and other operating revenues	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss)	10	1
Cost of revenues	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Gain (Loss)	($61)	($60)

Debt_Outstanding_Borrowings_De

Debt - Outstanding Borrowings (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]	'		'
Total	$3,659		$3,395
Unamortized discount	-10		-10
Fair value adjustments	10	[1]	11	[1]
Amounts due within one year	-24		-23
Total long-term debt due after one year	3,635		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	389		395
Debt instrument maturity year, start	1-Jan-14		'
Debt instrument maturity year, end	31-Dec-28		'
Consolidated subsidiaries: | Trade Receivables Securitization	'		'
Debt Instrument [Line Items]	'		'
Line of credit facility, expiration date	31-Dec-16		'
MPC Revolver	'		'
Debt Instrument [Line Items]	'		'
Borrowings outstanding	0		0
Line of credit facility, expiration date	14-Sep-17		'
3.500% senior notes due March 1, 2016 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Senior notes	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]	'		'
Senior notes	1,000		1,000
Debt instrument, maturity date	1-Mar-21		'
Debt instrument, interest rate	5.13%		'
6.500% senior notes due March 1, 2041 | Senior Notes	'		'
Debt Instrument [Line Items]	'		'
Senior notes	1,250		1,250
Debt instrument, maturity date	1-Mar-41		'
Debt instrument, interest rate	6.50%		'
MPLX Revolver | MPLX Operations LLC	'		'
Debt Instrument [Line Items]	'		'
Borrowings outstanding	270		0
Line of credit facility, expiration date	31-Oct-17		'
Trade Receivables Securitization | Consolidated subsidiaries:	'		'
Debt Instrument [Line Items]	'		'
Trade receivables securitization facility	$0		$0
[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 $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
MPC Revolver	'	'
Line of Credit Facility [Line Items]	'	'
Borrowings outstanding	$0	$0
Line of credit facility, expiration date	14-Sep-17	'
MPLX Operations LLC | MPLX Revolver	'	'
Line of Credit Facility [Line Items]	'	'
Borrowings outstanding	270	0
Line of credit facilitiy, borrowings during period	270	'
Interest rate during period	1.50%	'
Remaining borrowing capacity	230	'
Remaining borrowing capacity, percentage	46.00%	'
Line of credit facility, expiration date	31-Oct-17	'
Revolving Credit Facility | MPLX Operations LLC | MPLX Revolver	'	'
Line of Credit Facility [Line Items]	'	'
Borrowings outstanding	270	'
Letter of Credit | MPLX Operations LLC | MPLX Revolver	'	'
Line of Credit Facility [Line Items]	'	'
Borrowings outstanding	$0	'

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Net cash provided by operating activities included:	'	'
Interest paid (net of amounts capitalized)	$80	$83
Net income taxes paid to (refunded from) taxing authorities	5	-5
Non-cash investing and financing activities:	'	'
Capital lease obligations increase	0	61
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
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Supplemental Cash Flow Elements [Abstract]	'	'
Additions to property, plant and equipment	$267	$195
Acquisitions	0	1,377	[1]
Decrease in capital accruals	-19	-3
Total capital expenditures	$248	$1,569
[1]	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4.

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Beginning balance	($204)		($464)
Other comprehensive income (loss) before reclassifications	-42		76
Amounts reclassified from accumulated other comprehensive loss:	'		'
Amortization - prior service credit	-13	[1]	-13	[1]
Amortization of actuarial loss	14	[1]	22	[1]
Amortization of settlement loss	64	[1]	'
Tax effect	-24		-3
Other comprehensive income (loss)	-1		82
Ending balance	-205		-382
Accumulated Defined Benefit Plans Adjustment | Pension Benefits	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Beginning balance	-161		-432
Other comprehensive income (loss) before reclassifications	-43		67
Amounts reclassified from accumulated other comprehensive loss:	'		'
Amortization - prior service credit	-12	[1]	-11	[1]
Amortization of actuarial loss	13	[1]	21	[1]
Amortization of settlement loss	64	[1]	'
Tax effect	-24		-4
Other comprehensive income (loss)	-2		73
Ending balance	-163		-359
Accumulated Defined Benefit Plans Adjustment | Other Benefits	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Beginning balance	-50		-36
Other comprehensive income (loss) before reclassifications	1		9
Amounts reclassified from accumulated other comprehensive loss:	'		'
Amortization - prior service credit	-1	[1]	-2	[1]
Amortization of actuarial loss	1	[1]	1	[1]
Amortization of settlement loss	0	[1]	'
Tax effect	0		1
Other comprehensive income (loss)	1		9
Ending balance	-49		-27
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
Workers Compensation	'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'
Beginning balance	3		0
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	$3		$0
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 18.

Defined_Benefit_Pension_and_Ot2

Defined Benefit Pension and Other Postretirement Plans - Components of Net Periodic Benefit Costs (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits	'	'
Components of net periodic benefit cost:	'	'
Service cost	$23	$23
Interest cost	20	18
Expected return on plan assets	-28	-27
Amortization – prior service credit	-12	-11
Amortization – actuarial loss	13	21
Amortization – net settlement loss	64	0
Net periodic benefit cost	80	24
Other Benefits	'	'
Components of net periodic benefit cost:	'	'
Service cost	7	6
Interest cost	8	7
Expected return on plan assets	0	0
Amortization – prior service credit	-1	-2
Amortization – actuarial loss	1	1
Amortization – net settlement loss	0	0
Net periodic benefit cost	$15	$12

Defined_Benefit_Pension_and_Ot3

Defined Benefit Pension and Other Postretirement Plans - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Pension settlement expenses	($64)	$0
Pension Benefits | Funded Pension Plans	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Employer contributions	0	'
Pension Benefits | Unfunded Pension Plans	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Defined benefit plan, benefits paid	8	'
Other Benefits	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Pension settlement expenses	0	0
Other Benefits | Unfunded Pension Plans	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Defined benefit plan, benefits paid	$5	'

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans - Summary of Stock Option Award Activity (Detail) (Stock Options, USD $)	3 Months Ended
	Mar. 31, 2014
Stock Options	'
Number of Shares	'
Outstanding, beginning balance	5,147,837	[1]
Granted	327,100	[1]
Exercised	-455,999	[1]
Forfeited, canceled or expired	-19,293	[1]
Outstanding, ending balance	4,999,645	[1]
Weighted Average Exercise Price	'
Outstanding, beginning balance (in USD per share)	$40.08
Granted (in USD per share)	$83.37
Exercised (in USD per share)	$30.65
Forfeited, canceled or expired (in USD per share)	$50.05
Outstanding, ending balance (in USD per share)	$43.73
[1]	Includes an immaterial number of stock appreciation rights.

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans - Narrative (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Stock Options	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Grant date fair value (in USD per share)	$24.87
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)	$1.02

StockBased_Compensation_Plans_3

Stock-Based Compensation Plans - Summary of Restricted Stock Award Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Restricted Stock	'
Number of Shares	'
Outstanding, beginning balance	624,122
Granted	51,594
RS's Vested/RSU's Issued	-117,980
Forfeited	-14,840
Outstanding, ending balance	542,896
Weighted Average Grant Date Fair Value	'
Outstanding, beginning balance (in USD per share)	$61.11
Granted (in USD per share)	$83.45
RS's Vested/RSU's Issued (in USD per share)	$54.43
Forfeited (in USD per share)	$64.31
Outstanding, ending balance (in USD per share)	$64.60
Restricted Stock Units	'
Number of Shares	'
Outstanding, beginning balance	385,079
Granted	5,939
RS's Vested/RSU's Issued	0
Forfeited	0
Outstanding, ending balance	391,018
Weighted Average Grant Date Fair Value	'
Outstanding, beginning balance (in USD per share)	$33.96
Granted (in USD per share)	$89.96
RS's Vested/RSU's Issued (in USD per share)	$0
Forfeited (in USD per share)	$0
Outstanding, ending balance (in USD per share)	$34.81

StockBased_Compensation_Plans_4

Stock-Based Compensation Plans - Summary of Performance Unit Awards (Detail) (Performance Unit Awards)	3 Months Ended
	Mar. 31, 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 $)

3 Months Ended

3 Months Ended

3 Months Ended

Mar. 31, 2014

Dec. 31, 2013

Mar. 31, 2014

Feb. 01, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Galveston Bay Refinery and Related Assets

Galveston Bay Refinery and Related Assets

North Dakota Pipeline

Indemnification Agreement

Other Guarantees

Guarantee of Indebtedness of Others [Member]

Master Shelf Agreement [Member]

Standby Letters of Credit [Member]

Pending Litigation [Member]

Pending Litigation [Member]

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

$123,000,000

$123,000,000

'

'

'

'

'

'

'

'

'

'

Receivables for recoverable costs

50,000,000

51,000,000

'

'

'

'

'

'

'

'

'

'

Alleged amount overcharged from customers

'

'

'

'

'

'

'

'

'

'

'

89,000,000

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

'

'

'

'

'

'

122,000,000

172,000,000

41,000,000

25,000,000

'

'

Percentage of credit agreement agreed to reimburse

'

'

'

'

'

'

'

'

'

50.00%

'

'

Guarantee obligation current carrying value

'

'

'

'

'

2,000,000

'

'

'

'

'

'

Guarantee obligations maximum exposure per event

'

'

'

'

'

'

50,000,000

'

'

'

'

'

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

1,800,000,000

'

'

'

854,000,000

'

'

'

'

'

'

'

Maximum earnout provision payable to the company

'

'

$700,000,000

$700,000,000

'

'

'

'

'

'

'

'

Subsequent_Event_Subsequent_Ev1

Subsequent Event Subsequent Event (Detail) (USD $)	3 Months Ended		1 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Apr. 30, 2014	Apr. 02, 2014
			Felda Iffco Sdn Bhd [Member]	Felda Iffco Sdn Bhd [Member]
			Subsequent Event [Member]	Subsequent Event [Member]
				gallons_per_year
Subsequent Event [Line Items]	'	'	'	'
Cash paid for acquisition	$0	$1,493	$40	'
Plant capacity (in gallons per year)	'	'	'	60,000,000

Supplementary_Statistics_Suppl

Supplementary Statistics - Supplementary Statistics (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
Supplementary Statistics [Line Items]	'		'
Income from operations	$361		$1,156
Capital expenditures and investments	371	[1],[2],[3]	1,574	[1],[2],[3]
Galveston Bay Refinery and Related Assets	'		'
Supplementary Statistics [Line Items]	'		'
Fair value of contingent consideration as of acquisition date	'		600
Operating Segments	'		'
Supplementary Statistics [Line Items]	'		'
Income from operations	492	[4]	1,223	[4]
Capital expenditures and investments	340	[1]	1,546	[1],[5]
Operating Segments | Refining & Marketing	'		'
Supplementary Statistics [Line Items]	'		'
Income from operations	362		1,105
Capital expenditures and investments	178	[1]	1,420	[1],[5]
Operating Segments | Speedway	'		'
Supplementary Statistics [Line Items]	'		'
Income from operations	58		67
Capital expenditures and investments	32	[1]	36	[1],[5]
Operating Segments | Pipeline Transportation	'		'
Supplementary Statistics [Line Items]	'		'
Income from operations	72	[4]	51	[4]
Capital expenditures and investments	130	[1]	90	[1],[5]
Corporate and Other	'		'
Supplementary Statistics [Line Items]	'		'
Income from operations	-67	[4],[6]	-67	[4],[6]
Capital expenditures and investments	31	[1],[3]	28	[1],[3]
Capitalized interest	6		4
Segment Reconciling Items	'		'
Supplementary Statistics [Line Items]	'		'
Pension settlement expenses	($64)	[7]	$0
[1]	Capital expenditures include changes in capital accruals.
[2]	The three months ended March 31, 2013 includes the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, plus assumed liabilities. Total consideration includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 4 to the unaudited consolidated financial statements.
[3]	Includes capitalized interest $6 million and $4 million for the three months ended March 31, 2014 and 2013, respectively.
[4]	Corporate overhead costs attributable to MPLX are included in the Pipeline Transportation segment. These expenses are not allocated to the Refining & Marketing and Speedway segments.
[5]	The Refining & Marketing and Pipeline Transportation segments include the acquisition of the Galveston Bay Refinery and Related Assets. See Note 4.
[6]	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets.
[7]	See Note 18.

Supplementary_Statistics_Opera

Supplementary Statistics - Operating Statistics (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013
	BPD		BPD
Operating Statistics [Line Items ]	'		'
MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)	1,964,000	[1],[2]	1,895,000	[1],[2]
Refining & Marketing	'		'
Refining & Marketing Operating Statistics	'		'
Refining & Marketing Refined Product Sales Volume (thousands of barrels per day)	1,951,000	[2],[3]	1,880,000	[2],[3]
Refining & Marketing Gross Margin (dollars per barrel)	14.46	[2],[4]	15.29	[2],[4]
Crude Oil Capacity Utilization percent	85.00%	[2],[5]	93.00%	[2],[5]
Refinery Throughputs (thousands of barrels per day)	1,650,000	[2],[6]	1,671,000	[2],[6]
Sour Crude Oil Throughput percent	49.00%	[2]	54.00%	[2]
WTI-Priced Crude Oil Throughput percent	21.00%	[2]	22.00%	[2]
Refined Product Yields (thousands of barrels per day)	1,678,000	[2],[6]	1,704,000	[2],[6]
Inter-refinery transfers	59,000		29,000
Refinery Direct Operating Costs (dollars per barrel):	'		'
Planned turnaround and major maintenance	3.15	[2],[7]	1.15	[2],[7]
Depreciation and amortization	1.55	[2],[7]	1.42	[2],[7]
Other manufacturing	5.95	[2],[7],[8]	3.81	[2],[7],[8]
Total	10.65	[2],[7]	6.38	[2],[7]
Refining & Marketing | Crude oil refined	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	1,450,000	[2],[6]	1,433,000	[2],[6]
Refining & Marketing | Other charge and blendstocks	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	200,000	[2],[6]	238,000	[2],[6]
Refining & Marketing | Gasoline	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	837,000	[2],[6]	889,000	[2],[6]
Refining & Marketing | Distillates	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	514,000	[2],[6]	523,000	[2],[6]
Refining & Marketing | Propane	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	34,000	[2],[6]	32,000	[2],[6]
Refining & Marketing | Feedstocks and special products	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	220,000	[2],[6]	184,000	[2],[6]
Refining & Marketing | Heavy fuel oil	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	30,000	[2],[6]	30,000	[2],[6]
Refining & Marketing | Asphalt	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	43,000	[2],[6]	46,000	[2],[6]
Refining & Marketing | Gulf Coast:	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	1,071,000	[2],[9]	1,048,000	[2],[9]
Sour Crude Oil Throughput percent	60.00%	[2]	68.00%	[2]
WTI-Priced Crude Oil Throughput percent	3.00%	[2]	6.00%	[2]
Refined Product Yields (thousands of barrels per day)	1,096,000	[2],[9]	1,075,000	[2],[9]
Refinery Direct Operating Costs (dollars per barrel):	'		'
Planned turnaround and major maintenance	3.83	[2],[7]	0.87	[2],[7]
Depreciation and amortization	1.25	[2],[7]	1.13	[2],[7]
Other manufacturing	5.87	[2],[7],[8]	3.29	[2],[7],[8]
Total	10.95	[2],[7]	5.29	[2],[7]
Refining & Marketing | Gulf Coast: | Crude oil refined	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	860,000	[2],[9]	837,000	[2],[9]
Refining & Marketing | Gulf Coast: | Other charge and blendstocks	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	211,000	[2],[9]	211,000	[2],[9]
Refining & Marketing | Gulf Coast: | Gasoline	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	489,000	[2],[9]	531,000	[2],[9]
Refining & Marketing | Gulf Coast: | Distillates	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	319,000	[2],[9]	322,000	[2],[9]
Refining & Marketing | Gulf Coast: | Propane	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	21,000	[2],[9]	19,000	[2],[9]
Refining & Marketing | Gulf Coast: | Feedstocks and special products	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	245,000	[2],[9]	179,000	[2],[9]
Refining & Marketing | Gulf Coast: | Heavy fuel oil	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	15,000	[2],[9]	18,000	[2],[9]
Refining & Marketing | Gulf Coast: | Asphalt	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	7,000	[2],[9]	6,000	[2],[9]
Refining & Marketing | Midwest:	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	638,000	[9]	652,000	[9]
Sour Crude Oil Throughput percent	34.00%		35.00%
WTI-Priced Crude Oil Throughput percent	47.00%		45.00%
Refined Product Yields (thousands of barrels per day)	641,000	[9]	658,000	[9]
Refinery Direct Operating Costs (dollars per barrel):	'		'
Planned turnaround and major maintenance	1.71	[7]	1.56	[7]
Depreciation and amortization	1.91	[7]	1.82	[7]
Other manufacturing	5.54	[7],[8]	4.47	[7],[8]
Total	9.16	[7]	7.85	[7]
Refining & Marketing | Midwest: | Crude oil refined	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	590,000	[9]	596,000	[9]
Refining & Marketing | Midwest: | Other charge and blendstocks	'		'
Refining & Marketing Operating Statistics	'		'
Refinery Throughputs (thousands of barrels per day)	48,000	[9]	56,000	[9]
Refining & Marketing | Midwest: | Gasoline	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	348,000	[9]	358,000	[9]
Refining & Marketing | Midwest: | Distillates	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	195,000	[9]	201,000	[9]
Refining & Marketing | Midwest: | Propane	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	13,000	[9]	13,000	[9]
Refining & Marketing | Midwest: | Feedstocks and special products	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	33,000	[9]	34,000	[9]
Refining & Marketing | Midwest: | Heavy fuel oil	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	16,000	[9]	12,000	[9]
Refining & Marketing | Midwest: | Asphalt	'		'
Refining & Marketing Operating Statistics	'		'
Refined Product Yields (thousands of barrels per day)	36,000	[9]	40,000	[9]
Speedway	'		'
Speedway Operating Statistics	'		'
Convenience stores at period-end	1,482		1,463
Gasoline and distillate sales (millions of gallons)	773,000,000		745,000,000
Gasoline and distillate gross margin (dollars per gallon)	0.1156	[10]	0.1301	[10]
Merchandise sales (in millions)	722		711
Merchandise gross margin (in millions)	192		184
Same store gasoline sales volume (period over period) percentage	-0.70%		0.70%
Merchandise sales excluding cigarettes (period over period) percentage	5.30%	[11]	0.80%	[11]
Pipeline Transportation	'		'
Pipeline Transportation Operating Statistics	'		'
Pipeline Throughputs (thousands of barrels per day)	1,963,000	[12]	2,189,000	[12]
Pipeline Transportation | Crude oil pipelines	'		'
Pipeline Transportation Operating Statistics	'		'
Pipeline Throughputs (thousands of barrels per day)	1,144,000	[12]	1,272,000	[12]
Pipeline Transportation | Refined products pipelines	'		'
Pipeline Transportation Operating Statistics	'		'
Pipeline Throughputs (thousands of barrels per day)	819,000	[12]	917,000	[12]
[1]	Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers.
[2]	Includes the impact of the Galveston Bay Refinery and Related Assets beginning on the February 1, 2013 acquisition date.
[3]	Includes intersegment sales.
[4]	Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs.
[5]	Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities.
[6]	Excludes inter-refinery volumes of 59 mbpd and 29 mbpd for the three months ended March 31, 2014 and 2013, respectively.
[7]	Per barrel of total refinery throughputs.
[8]	Includes utilities, labor, routine maintenance and other operating costs.
[9]	Includes inter-refinery transfer volumes.
[10]	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.
[11]	Excludes cigarettes.
[12]	On owned common-carrier pipelines, excluding equity method investments.