Marathon Petroleum (MPC) 10-K 28 Feb 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2013	Feb. 14, 2014	Jun. 28, 2013
Entity Information [Line Items]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'MPC	'	'
Entity Registrant Name	'Marathon Petroleum Corp	'	'
Entity Central Index Key	'0001510295	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	294,564,231	'
Entity Public Float	'	'	$22.50

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues and other income:	'	'	'
Sales and other operating revenues (including consumer excise taxes)	$100,152	$82,235	$78,583
Sales to related parties	8	8	55
Income from equity method investments	36	26	50
Net gain on disposal of assets	6	177	12
Other income	52	46	59
Total revenues and other income	100,254	82,492	78,759
Costs and expenses:	'	'	'
Cost of revenues (excludes items below)	87,401	68,668	65,795
Purchases from related parties	357	280	1,916
Consumer excise taxes	6,263	5,709	5,114
Depreciation and amortization	1,220	995	891
Selling, general and administrative expenses	1,248	1,223	1,059
Other taxes	340	270	239
Total costs and expenses	96,829	77,145	75,014
Income from operations	3,425	5,347	3,745
Related party net interest and other financial income	0	1	35
Net interest and other financial income (costs)	-179	-110	-61
Income before income taxes	3,246	5,238	3,719
Provision for income taxes	1,113	1,845	1,330
Net income	2,133	3,393	2,389
Less net income attributable to noncontrolling interests	21	4	0
Net income attributable to MPC	$2,112	$3,389	$2,389
Basic:	'	'	'
Net income attributable to MPC per share (in USD per share)	$6.69	$9.95	$6.70
Weighted average shares outstanding (in shares)	315	340	356
Diluted:	'	'	'
Net income attributable to MPC per share (in USD per share)	$6.64	$9.89	$6.67
Weighted average shares outstanding (in shares)	317	342	357
Dividends paid (in USD per share)	$1.54	$1.20	$0.45

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]	'	'	'
Net income	$2,133	$3,393	$2,389
Defined benefit postretirement and post-employment plans:	'	'	'
Actuarial changes, net of tax of $174, $47, and ($151)	294	78	-248
Prior service costs, net of tax of ($19), $203, and $2	-34	337	4
Other, net of tax of $-, $- and $-	0	0	-1
Other comprehensive income (loss)	260	415	-245
Comprehensive income	2,393	3,808	2,144
Less comprehensive income attributable to noncontrolling interests	21	4	0
Comprehensive income attributable to MPC	$2,372	$3,804	$2,144

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]	'	'	'
Actuarial changes, tax	$174	$47	($151)
Prior service cost, tax	-19	203	2
Other, tax	$0	$0	$0

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$2,292	$4,860
Receivables, less allowance for doubtful accounts of $9 and $10	5,559	4,610
Inventories	4,689	3,449
Other current assets	197	110
Total current assets	12,737	13,029
Equity method investments	463	321
Property, plant and equipment, net	13,921	12,643
Goodwill	938	930
Other noncurrent assets	326	300
Total assets	28,385	27,223
Current liabilities:	'	'
Accounts payable	8,234	6,785
Payroll and benefits payable	406	364
Consumer excise taxes payable	373	325
Accrued taxes	513	598
Long-term debt due within one year	23	19
Other current liabilities	275	112
Total current liabilities	9,824	8,203
Long-term debt	3,373	3,342
Deferred income taxes	2,304	2,050
Defined benefit postretirement plan obligations	771	1,266
Deferred credits and other liabilities	781	257
Total liabilities	17,053	15,118
Commitments and contingencies (see Note 25)	'	'
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 - 362 million and 361 million shares (par value $0.01 per share, 1 billion shares authorized)	4	4
Held in treasury, at cost - 65 million and 28 million shares	-4,155	-1,253
Additional paid-in capital	9,768	9,527
Retained earnings	5,507	3,880
Accumulated other comprehensive loss	-204	-464
Total MPC stockholders’ equity	10,920	11,694
Noncontrolling interests	412	411
Total equity	11,332	12,105
Total liabilities and equity	$28,385	$27,223

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Receivables, allowance for doubtful accounts	$9	$10
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, par value (in USD per share)	$0.01	'
Preferred stock, shares authorized	30,000,000	'
Common stock, shares issued	362,000,000	361,000,000
Common stock, par value (in USD per share)	$0.01	'
Common stock, shares authorized	1,000,000,000	'
Treasury stock, shares	65,000,000	28,000,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities:	'	'	'
Net income	$2,133	$3,393	$2,389
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Depreciation and amortization	1,220	995	891
Pension and other postretirement benefits, net	-124	153	-90
Deferred income taxes	23	492	123
Net gain on disposal of assets	-6	-177	-12
Equity method investments, net	-18	11	-2
Changes in the fair value of derivative instruments	-21	59	-57
Changes in:	'	'	'
Current receivables	-940	851	-1,177
Inventories	-305	-115	-255
Current accounts payable and accrued liabilities	1,464	-1,223	1,502
All other, net	-21	53	-3
Net cash provided by operating activities	3,405	4,492	3,309
Investing activities:	'	'	'
Additions to property, plant and equipment	-1,206	-1,369	-1,185
Acquisitions	-1,515	-190	-74
Disposal of assets	16	53	144
Investments in related party debt securities – purchases	0	0	-10,326
Investments in related party debt securities – redemptions	0	0	12,730
Investments—acquisition, loans and contributions	-151	-57	-56
Investments—redemptions and repayments	77	108	53
All other, net	23	3	9
Net cash provided by (used in) investing activities	-2,756	-1,452	1,295
Financing activities:	'	'	'
Long-term debt payable to Marathon Oil and subsidiaries – borrowings	0	0	7,748
Long-term debt payable to Marathon Oil and subsidiaries – repayments	0	0	-11,366
Long-term debt – borrowings	0	0	2,989
Long-term debt – repayments	-21	-17	-12
Debt issuance costs	-4	-6	-60
Issuance of common stock	48	108	1
Common stock repurchased	-2,793	-1,350	0
Dividends paid	-484	-407	-160
Net proceeds from issuance of MPLX LP common units	0	407	0
Distributions to noncontrolling interests	-21	0	0
Distributions to Marathon Oil Corporation	0	0	-783
Tax settlement with Marathon Oil Corporation	39	0	0
All other, net	19	6	0
Net cash used in financing activities	-3,217	-1,259	-1,643
Net increase (decrease) in cash and cash equivalents	-2,568	1,781	2,961
Cash and cash equivalents at beginning of period	4,860	3,079	118
Cash and cash equivalents at end of period	$2,292	$4,860	$3,079

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity / Net Investment (USD $)	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Net Investment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
In Millions, unless otherwise specified
Beginning balance at Dec. 31, 2010	$8,244	$0	$0	$0	$0	$8,867	($623)	$0
Beginning balance (in shares) at Dec. 31, 2010	'	0	0	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'
Net income	2,389	'	'	'	1,058	1,331	'	0
Dividends declared	-160	'	'	'	-160	'	'	'
Distributions to Marathon Oil Corporation	-737	'	'	'	'	-726	-11	'
Other comprehensive loss	-245	'	'	'	'	'	-245	'
Shares issued (returned) - stock based compensation	9	'	'	9	'	'	'	'
Stock-based compensation	5	'	'	5	'	'	'	0
Reclassification of net investment to additional paid-in capital	0	'	'	9,472	'	-9,472	'	'
Issuance of common stock at spinoff	0	4	'	-4	'	'	'	'
Shares issued - stock-based compensation (in shares)	'	1	'	'	'	'	'	'
Issuance of common stock at spinoff (in shares)	'	356	'	'	'	'	'	'
Ending balance at Dec. 31, 2011	9,505	4	0	9,482	898	0	-879	0
Ending balance (in shares) at Dec. 31, 2011	'	357	0	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'
Net income	3,393	'	'	'	3,389	'	'	4
Dividends declared	-407	'	'	'	-407	'	'	'
Other comprehensive loss	415	'	'	'	'	'	415	'
Shares repurchased	-1,350	'	-1,250	-100	'	'	'	'
Shares issued (returned) - stock based compensation	105	'	-3	108	'	'	'	'
Stock-based compensation	46	'	'	46	'	'	'	0
Issuance of MPLX LP common units	407	'	'	'	'	'	'	407
Other	-9	'	'	-9	'	'	'	'
Shares repurchased (in shares)	'	'	-28	'	'	'	'	'
Shares issued - stock-based compensation (in shares)	'	4	'	'	'	'	'	'
Ending balance at Dec. 31, 2012	12,105	4	-1,253	9,527	3,880	0	-464	411
Ending balance (in shares) at Dec. 31, 2012	'	361	28	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'
Net income	2,133	'	'	'	2,112	'	'	21
Dividends declared	-485	'	'	'	-485	'	'	'
Distributions to noncontrolling interests	-21	'	'	'	'	'	'	-21
Other comprehensive loss	260	'	'	'	'	'	260	'
Shares repurchased	-2,793	'	-2,893	100	'	'	'	'
Shares issued (returned) - stock based compensation	38	'	-9	47	'	'	'	'
Stock-based compensation	56	'	'	55	'	'	'	1
Tax settlement with Marathon Oil Corporation	39	'	'	39	'	'	'	'
Shares repurchased (in shares)	'	'	-37	'	'	'	'	'
Shares issued - stock-based compensation (in shares)	'	1	'	'	'	'	'	'
Ending balance at Dec. 31, 2013	$11,332	$4	($4,155)	$9,768	$5,507	$0	($204)	$412
Ending balance (in shares) at Dec. 31, 2013	'	362	65	'	'	'	'	'

Description_Of_The_Business_Sp

Description Of The Business, Spinoff And Basis Of Presentation	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Description Of The Business, Spinoff And Basis Of Presentation	'
	Description of the Business, Spinoff 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 10 for additional information about our operations.
	Spinoff – On May 25, 2011, the Marathon Oil Corporation (“Marathon Oil”) board of directors approved the spinoff of its Refining, Marketing & Transportation Business (“RM&T Business”) into an independent, publicly traded company, Marathon Petroleum Corporation (“MPC”), through the distribution of MPC common stock to the stockholders of Marathon Oil common stock. In accordance with a separation and distribution agreement between Marathon Oil and MPC, the distribution of MPC common stock was made on June 30, 2011, with Marathon Oil stockholders receiving one share of MPC common stock for every two shares of Marathon Oil common stock held (the “Spinoff”). Following the Spinoff, Marathon Oil retained no ownership interest in MPC, and each company had separate public ownership, boards of directors and management. All subsidiaries and equity method investments not contributed by Marathon Oil to MPC remained with Marathon Oil and, together with Marathon Oil, are referred to as the “Marathon Oil Companies.” On July 1, 2011, our common stock began trading “regular-way” on the New York Stock Exchange under the ticker symbol “MPC.”
	Basis of Presentation – Prior to the Spinoff on June 30, 2011, our results of operations and cash flows consisted of the RM&T Business, which represented a combined reporting entity. Subsequent to the Spinoff, our results of operations and cash flows consist of consolidated MPC activities. All significant intercompany transactions and accounts have been eliminated.
	The consolidated statement of income for the period prior to the Spinoff included expense allocations for certain corporate functions historically performed by the Marathon Oil Companies, including allocations of general corporate expenses related to executive oversight, accounting, treasury, tax, legal, procurement and information technology. Those allocations were based primarily on specific identification, headcount or computer utilization. Our management believes the assumptions underlying the consolidated financial statements, including the assumptions regarding allocating general corporate expenses from the Marathon Oil Companies, are reasonable. However, these consolidated financial statements do not include all of the actual expenses that would have been incurred had we been a stand-alone company during the period presented prior to the Spinoff and may not reflect our consolidated results of operations and cash flows had we been a stand-alone company during the period presented. Actual costs that would have been incurred if we had been a stand-alone company would depend upon multiple factors, including organizational structure and strategic decisions made in various areas, including information technology and infrastructure. Subsequent to the Spinoff, we are performing these functions using internal resources or services provided by third parties, certain of which were provided by the Marathon Oil Companies during a transition period pursuant to a transition services agreement, which terminated June 30, 2012. See Note 7.

Summary_Of_Principal_Accountin

Summary Of Principal Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary Of Principal Accounting Policies	'
	Summary of Principal Accounting Policies
	Principles applied in consolidation – These consolidated financial statements include the accounts of our majority-owned, controlled subsidiaries. We consolidate MPLX, in which we own a 73.6 percent controlling financial interest, and we record a noncontrolling interest for the 26.4 percent interest owned by the public.
	Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority shareholders have substantive participating rights in the investee. Income from equity method investments represents our proportionate share of net income generated by the equity method investees.
	Equity method investments are generally carried at our share of net assets plus loans and advances. Such investments are assessed for impairment whenever changes in the facts and circumstances indicate a loss in value has occurred, if the loss is deemed to be other than temporary. When the loss is deemed to be other than temporary, the carrying value of the equity method investment is written down to fair value, and the amount of the write-down is included in net income. Differences in the basis of the investments and the separate net asset values of the investees, if any, are amortized into net income over the remaining useful lives of the underlying assets and liabilities, except for the excess related to goodwill.
	Use of estimates – The preparation of financial statements in accordance with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the respective reporting periods.
	Revenue recognition – Revenues are recognized when products are shipped or services are provided to customers, title is transferred, the sales price is fixed or determinable and collectability is reasonably assured. Costs associated with revenues are recorded in cost of revenues. Shipping and other transportation costs billed to our customers are presented on a gross basis in revenues and cost of revenues.
	Rebates from vendors are recognized as a reduction of cost of revenues when the initiating transaction occurs. Incentives that are derived from contractual provisions are accrued based on past experience and recognized in cost of revenues. Rebates to customers are reflected as a reduction of revenue and are accrued for in accounts payable on the consolidated balance sheets.
	Crude oil and refined product exchanges and matching buy/sell transactions – We enter into exchange contracts and matching buy/sell arrangements whereby we agree to deliver a particular quantity and quality of crude oil or refined products at a specified location and date to a particular counterparty and to receive from the same counterparty the same commodity at a specified location on the same or another specified date. The exchange receipts and deliveries are nonmonetary transactions, with the exception of associated grade or location differentials that are settled in cash. The matching buy/sell purchase and sale transactions are settled in cash. Both exchange and matching buy/sell transactions are accounted for as exchanges of inventory and no revenues are recorded. The exchange transactions are recognized at the carrying amount of the inventory transferred.
	Consumer excise taxes – We are required by various governmental authorities, including countries, states and municipalities, to collect and remit taxes on certain consumer products. Such taxes are presented on a gross basis in revenues and costs and expenses in the consolidated statements of income.
	Cash and cash equivalents – Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid debt instruments with maturities of three months or less.
	Restricted cash - Restricted cash consists of cash advances to be used for the operation and maintenance of an operated pipeline system. At December 31, 2013, the amount of restricted cash included in other current assets on the consolidated balance sheets was $7 million.
	Accounts receivable and allowance for doubtful accounts – Our receivables primarily consist of customer accounts receivable. The allowance for doubtful accounts is the best estimate of the amount of probable credit losses in customer accounts receivable and is based on historical write-off experience. We review the allowance quarterly and past-due balances over 180 days are reviewed individually for collectability. All other customer receivables are recorded at the invoiced amounts and generally do not bear interest. Account balances for these customer receivables are generally charged directly to bad debt expense when it becomes probable the receivable will not be collected.
	Approximately 38 percent and 42 percent of our accounts receivable balances at December 31, 2013 and 2012, respectively, are related to sales of crude oil or refinery feedstocks to customers with whom we have master netting agreements. We have master netting agreements with more than 100 companies engaged in the crude oil or refinery feedstock trading and supply business or the petroleum refining industry. A master netting agreement generally provides for a once per month net cash settlement of the accounts receivable from and the accounts payable to a particular counterparty.
	Inventories – Inventories are carried at the lower of cost or market value. Cost of inventories is determined primarily under the last-in, first-out (“LIFO”) method.
	Derivative instruments – We use derivatives to economically hedge a portion of our exposure to commodity price risk and, historically, to interest rate risk. We also have limited authority to use selective derivative instruments that assume market risk. All derivative instruments are recorded at fair value. Commodity derivatives are reflected on the consolidated balance sheets on a net basis by futures commission merchant, as they are governed by master netting agreements. Cash flows related to derivatives used to hedge commodity price risk and interest rate risk are classified in operating activities with the underlying transactions.
	Fair value accounting hedges – We used interest rate swaps to hedge our exposure to interest rate risk associated with fixed interest rate debt in our portfolio. Changes in the fair values of both the hedged item and the related derivative were recognized immediately in net income with an offsetting effect included in the basis of the hedged item. The net effect was to report in net income the extent to which the accounting hedge was not effective in achieving offsetting changes in fair value. We terminated our interest rate swap agreements during 2012. There was a gain on the termination of the agreements, which has been accounted for as an adjustment to our long-term debt balance. The gain is being amortized over the remaining life of the associated debt, which reduces our interest expense.
	Derivatives not designated as accounting hedges –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. Changes in the fair value of derivatives not designated as accounting hedges are recognized immediately in net income.
	Contingent credit features – Our derivative instruments contain no significant contingent credit features.
	Concentrations of credit risk – All of our financial instruments, including derivatives, involve elements of credit and market risk. The most significant portion of our credit risk relates to nonperformance by counterparties. The counterparties to our financial instruments consist primarily of major financial institutions and companies within the energy industry. To manage counterparty risk associated with financial instruments, we select and monitor counterparties based on an assessment of their financial strength and on credit ratings, if available. Additionally, we limit the level of exposure with any single counterparty.
	Property, plant and equipment – Property, plant and equipment are recorded at cost and depreciated on a straight-line basis over the estimated useful lives of the assets, which range from four to 42 years. Such assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If the sum of the expected undiscounted future cash flows from the use of the asset and its eventual disposition is less than the carrying amount of the asset, an impairment loss is recognized based on the fair value of the asset.
	When items of property, plant and equipment are sold or otherwise disposed of, any gains or losses are reported in net income. Gains on the disposal of property, plant and equipment are recognized when earned, which is generally at the time of closing. If a loss on disposal is expected, such losses are recognized when the assets are classified as held for sale.
	Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset.
	Goodwill – Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in the acquisition of a business. Goodwill is not amortized, but rather is tested for impairment annually and when events or changes in circumstances indicate that the fair value of a reporting unit with goodwill has been reduced below carrying value. The impairment test requires allocating goodwill and other assets and liabilities to reporting units. The fair value of each reporting unit is determined and compared to the book value of the reporting unit. If the fair value of the reporting unit is less than the book value, including goodwill, the implied fair value of goodwill is calculated. The excess, if any, of the book value over the implied fair value of goodwill is charged to net income.
	Major maintenance activities – Costs for planned turnaround, major maintenance and engineered project activities are expensed in the period incurred. These types of costs include contractor repair services, materials and supplies, equipment rentals and our labor costs.
	Environmental costs – Environmental expenditures are capitalized if the costs mitigate or prevent future contamination or if the costs improve environmental safety or efficiency of the existing assets. We recognize remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs can be reasonably estimated. The timing of remediation accruals coincides with completion of a feasibility study or the commitment to a formal plan of action. Remediation liabilities are accrued based on estimates of known environmental exposure and are discounted when the estimated amounts are reasonably fixed and determinable. If recoveries of remediation costs from third parties are probable, a receivable is recorded and is discounted when the estimated amount is reasonably fixed and determinable.
	Asset retirement obligations – The fair value of asset retirement obligations is recognized in the period in which the obligations are incurred if a reasonable estimate of fair value can be made. Conditional asset retirement obligations for removal and disposal of fire-retardant material from certain refining facilities have been recognized. The fair values recorded for such obligations are based on the most probable current cost projections. The recorded asset retirement obligations are not material to the consolidated financial statements.
	Asset retirement obligations have not been recognized for some assets because the fair value cannot be reasonably estimated since the settlement dates of the obligations are indeterminate. Such obligations will be recognized in the period when sufficient information becomes available to estimate a range of potential settlement dates. The asset retirement obligations principally include the removal of underground storage tanks at our owned and some of our leased convenience stores at or near the time of closure and hazardous material disposal and removal or dismantlement requirements associated with the closure of certain refining, terminal and pipeline assets.
	Our practice is to keep our assets in good operating condition through routine repair and maintenance of component parts in the ordinary course of business and by continuing to make improvements based on technological advances. As a result, we believe that these assets have no expected settlement date for purposes of estimating asset retirement obligations since the dates or ranges of dates upon which we would retire these assets cannot be reasonably estimated at this time.
	Income taxes – Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their tax bases. Deferred tax assets are recorded when it is more likely than not that they will be realized. The realization of deferred tax assets is assessed periodically based on several factors, primarily our expectation to generate sufficient future taxable income.
	For periods prior to the Spinoff, our taxable income was included in the consolidated U.S. federal income tax returns of Marathon Oil and in a number of consolidated state income tax returns. In the accompanying consolidated financial statements, for periods prior to the Spinoff our provision for income taxes was computed as if we were a stand-alone tax-paying entity.
	Stock-based compensation arrangements – The fair value of stock options and stock-settled stock appreciation rights (collectively, “stock option awards”) granted to our employees is estimated on the date of grant using the Black-Scholes option pricing model. The model employs various assumptions, based on management’s estimates at the time of grant, which impact the calculation of fair value and ultimately, the amount of expense that is recognized over the vesting period of the stock option award. Of the required assumptions, the expected life of the stock option award and the expected volatility of our stock price have the most significant impact on the fair value calculation. The average expected life is based on our historical employee exercise behavior. The assumption for expected volatility of our stock price reflects a weighting of 33 percent of our common stock volatility and 67 percent of the historical volatility for a selected group of peer companies.
	The fair value of restricted stock awards granted to our employees is determined based on the fair market value of our common stock on the date of grant. The fair value of performance unit awards granted to our employees is estimated on the date of grant using a Monte Carlo valuation model.
	Our stock-based compensation expense is recognized based on management’s estimate of the awards that are expected to vest, using the straight-line attribution method for all service-based awards with a graded vesting feature. If actual forfeiture results are different than expected, adjustments to recognized compensation expense may be required in future periods. Unearned stock-based compensation is charged to equity when restricted stock awards are granted. Compensation expense is recognized over the vesting period and is adjusted if conditions of the restricted stock award are not met. For periods prior to the Spinoff, we recorded Marathon Oil stock-based compensation expense as non-cash capital contributions.
	Renewable fuel identification numbers ("RINs") - We purchase RINs to satisfy a portion of our Renewable Fuel Standard ("RFS2") compliance. We record a short-term intangible asset, included in other current assets on the balance sheet, for RINs owned in excess of our anticipated current period compliance requirements. The asset value is based on the product of the excess RINs as of the balance sheet date, if any, and the average cost of our RINs. We record a current liability, included in other current liabilities on the balance sheet, when we are deficient RINs based on the product of the deficient RINs as of the balance sheet date, if any, and the market price of the RINs at the balance sheet date. The cost of RINs used for compliance is reflected in cost of revenues. Any gains or losses on the sale or expiration of RINs are classified as other income.

Accounting_Standards

Accounting Standards	12 Months Ended
	Dec. 31, 2013
Accounting Changes and Error Corrections [Abstract]	'
Accounting Standards	'
	Accounting Standards
	Recently Adopted
	In February 2013, the Financial Accounting Standards Board (“FASB”) issued an accounting standards update that requires an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. If the amount reclassified is required under U.S. generally accepted accounting principles ("US GAAP") to be reclassified to net income in its entirety in the same reporting period, an entity is required to present, either on the face of the financial statements or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income. For other amounts not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional detail about those amounts. The accounting standards update was to be applied prospectively for interim and annual periods beginning with the first quarter of 2013. The adoption of this accounting standards update in the first quarter of 2013 did not have an impact on our consolidated results of operations, financial position or cash flows. The new required disclosures are included in Note 21.
	In July 2012, the FASB issued an accounting standards update that gives an entity the option to first assess qualitatively whether it is more likely than not that an indefinite-lived intangible asset is impaired. If, through the qualitative assessment, an entity determines that it is more likely than not that the intangible asset is impaired, the quantitative impairment test must then be performed. The accounting standards update was effective for annual and interim impairment tests performed in fiscal years beginning after September 15, 2012. Early adoption was permitted. The adoption of this accounting standards update in the first quarter of 2013 did not have an impact on our consolidated results of operations, financial position or cash flows. We perform the annual intangible asset impairment testing in the fourth quarter.
	In December 2011, the FASB issued an accounting standards update which was amended in January 2013 that requires disclosure of additional information related to recognized derivative instruments, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transactions that are offset or are not offset but are subject to an enforceable netting agreement. The purpose of the requirement is to help users evaluate the effect or potential effect of offsetting and related netting arrangements on an entity’s financial position. The update was to be applied retrospectively and was effective for interim and annual periods beginning with the first quarter of 2013. The adoption of this accounting standards update in the first quarter of 2013 did not have an impact on our consolidated results of operations, financial position or cash flows. The new required disclosures are included in Note 17.

MPLX_LP

MPLX LP	12 Months Ended
	Dec. 31, 2013
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. In October 2012, MPLX completed its initial public offering of 19,895,000 common units. Net proceeds to MPLX from the sale of the units were $407 million. 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. The initial public offering represented the sale of a 26.4 percent interest in MPLX.
	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 an additional five percent interest in Pipe Line Holdings to MPLX for $100 million, increasing MPLX's ownership interest in Pipe Line Holdings to 56 percent and reducing our ownership to 44 percent.
	On February 27, 2014, we announced the sale of an additional 13 percent interest in Pipe Line Holdings to MPLX for $310 million, effective March 1, 2014. Subsequent to this transaction, MPLX will own a 69 percent general partner interest in Pipe Line Holdings and we will own a 31 percent limited partner interest. MPLX intends to finance this transaction with $40 million of cash on-hand and by borrowing $270 million on its revolving credit agreement.
	Commercial Agreements
	MPLX generates revenue primarily by charging tariffs for transporting crude oil, refined products and other hydrocarbon-based products through their pipelines and at their barge dock and fees for storing crude oil and products at their storage facilities. They are also the operator of additional crude oil and product pipelines owned by us and third parties for which they are paid operating fees. They do not take ownership of the crude oil or products that they transport and store for their customers, and they do not engage in the trading of any commodities.
	We have entered into nine long-term, fee-based transportation agreements and five long-term, fee-based storage services agreements with MPLX. Under these agreements, MPLX provides transportation and storage services to us, and we commit to provide MPLX with minimum quarterly throughput and storage volumes of crude oil and products and minimum storage volumes of butane. These agreements range from three to ten years in length, and most automatically renew unless terminated by either party. We believe the terms and conditions under these commercial agreements, as well as the other initial agreements we entered into with MPLX are generally no less favorable to either party than those that could have been negotiated with unaffiliated parties with respect to similar services.
	Under the transportation services agreements, if we fail to transport our minimum throughput volumes during any quarter, then we will pay MPLX a deficiency payment equal to the volume of the deficiency multiplied by the tariff rate then in effect. Any such deficiency payments may then be applied as a credit for volumes transported on the applicable pipeline system in excess of its minimum volume commitment during the following four or eight quarters under the terms of the applicable transportation services agreement. As of December 31, 2013, we had $34 million in volume deficiency credits. If the minimum capacity of the pipeline falls below the level of our commitment at any time or if capacity on the pipeline is required to be allocated among shippers because volume nominations exceed available capacity, depending on the cause of the reduction in capacity, our commitment may be reduced or we will receive a credit for our minimum volume commitment for that period. In addition to our minimum volume commitment, we are responsible for any loading, handling, transfer and other charges with respect to volumes MPLX transports for us. If MPLX agrees to make any capital expenditures at our request, we will reimburse MPLX for, or MPLX will have the right in certain circumstances, to file for an increased tariff rate to recover the actual cost of such capital expenditures. The transportation services agreements include provisions that permit us to suspend, reduce or terminate our obligations under the applicable agreement if certain events occur. These events include us deciding to permanently or indefinitely suspend refining operations at one or more of our refineries for at least twelve consecutive months and certain force majeure events that would prevent MPLX or us from performing under the applicable agreement.
	Under the storage services agreements, MPLX is obligated to make available to us on a firm basis the available storage capacity at the tank farms and butane cavern, and we pay MPLX a per-barrel fee for such storage capacity, regardless of whether we fully utilize the available capacity. Beginning on January 1, 2014, the storage services agreements are adjusted based on changes in the producer price index.
	Operating Agreements
	At the closing of the initial public offering of MPLX, we entered into an operating services agreement with MPLX under which MPLX operates various pipeline systems owned by us. In addition, under existing operating service agreements, MPLX continues to operate various pipeline systems owned by us and third parties. Under these operating services agreements MPLX receives an operating fee for operating the assets and is reimbursed for all direct and indirect costs associated with operating the assets. The operating fees under most of these agreements are indexed for inflation. These agreements range from one to five years in length and automatically renew unless terminated by either party.
	Management Services Agreements
	Prior to the closing of the initial public offering of MPLX, MPLX entered into two management services agreements with us under which MPLX provides certain management services to us with respect to certain of our retained pipeline assets. MPLX receives fixed annual fees under the agreements for providing the required management services, which is adjusted annually for inflation and based on changes in the scope of management services provided.
	Omnibus Agreement
	Upon the closing of the initial public offering of MPLX, we entered into an omnibus agreement with MPLX that addresses MPLX’s payment of a fixed annual fee to us for the provision of executive management services and MPLX’s reimbursement to us for the provision of certain general and administrative services to MPLX, as well as our indemnification of MPLX for certain matters, including environmental, title and tax matters.
	Employee Services Agreements
	Prior to the closing of the initial public offering of MPLX, we entered into two employee services agreements with MPLX under which MPLX reimburses us for the provision of certain operational and management services in support of their pipelines, barge dock, butane cavern and tank farms.

Acquisitions_and_Investments

Acquisitions and Investments	12 Months Ended
	Dec. 31, 2013
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 the 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. 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 as discussed below. These assets complement our current geographic footprint and align with our strategic initiative of growing in existing and contiguous markets to enhance our portfolio. The transaction was funded with cash on hand.
	As of the acquisition date, we recorded a contingent liability of $600 million, representing the preliminary fair value of contingent consideration we expect to pay to BP related to the earnout provision. The fair value of the contingent consideration was estimated using an income approach. 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. We used internal and external forecasts for the crack spread and internal forecasts for refinery throughput volumes and applied an appropriate risk-adjusted discount rate to the range of cash flows indicated by various scenarios to determine the fair value of the arrangement. The fair value of the contingent consideration is reassessed each quarter, with changes in fair value recorded in cost of revenues. The fair value of the contingent consideration was $625 million at December 31, 2013, which includes $159 million classified as current. See Note 17 for additional information.
	The transaction provided for a post-closing adjustment for inventory, which was finalized for $9 million, reducing our total consideration.
	The components of the fair value of consideration transferred are as follows:
	(In millions)
	Cash	$	1,491
	Fair value of contingent consideration as of acquisition date	600
	Payable to seller	6
	Post-closing adjustment	(9		)
	Total consideration	$	2,088
	During the fourth quarter of 2013, an independent appraisal of the assets acquired and liabilities assumed and other evaluations were completed and finalized. Minor updates to the preliminary fair value measurements of assets acquired and liabilities assumed were made during the second and third quarters of 2013. The following table summarizes the final amounts assigned to the assets acquired and liabilities assumed as of the acquisition date.
	(In millions)
	Inventories	$	935
	Other current assets	1
	Property, plant and equipment, net	1,274
	Other noncurrent assets	88
	Accounts payable	(12		)
	Payroll and benefits payable	(14		)
	Long-term debt due within one year(a)	(2		)
	Other current liabilities	(6		)
	Long-term debt(a)	(58		)
	Defined benefit postretirement plan obligations	(43		)
	Deferred credits and other liabilities	(75		)
	Total	$	2,088
	(a)	Represents a capital lease obligation assumed.
	Neither goodwill nor a gain from a bargain purchase was recognized in conjunction with the Galveston Bay Refinery and Related Assets acquisition.
	Other noncurrent assets consist of a $20 million intangible asset related to customer relationships and a $68 million intangible asset related to prepaid licensed refinery technology agreements. The intangible assets related to customer relationships and prepaid licensed refinery technology agreements are being amortized on a straight-line basis over four and 15 years, respectively. The weighted average life over which these acquired intangibles are being amortized is approximately 13 years.
	We recognized $7 million of acquisition-related costs associated with the Galveston Bay Refinery and Related Assets acquisition. These costs were expensed and were included in selling, general and administrative expenses.
	Our refineries and related assets are operated as an integrated system. As the information is not available by refinery, it is not practicable to disclose the revenues and net income associated with the acquisition that were included in our consolidated statements of income for 2013.
	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)	2013			2012
	Sales and other operating revenues (including consumer excise taxes)	$	102,120		$	104,165
	Net income attributable to MPC	2,167			3,625
	Net income attributable to MPC per share - basic	$	6.88		$	10.66
	Net income attributable to MPC per share - diluted	6.84			10.6
	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. The pro forma information reflects revisions made during the second and third quarters of 2013 to the estimated fair values of assets acquired and liabilities assumed.
	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.
	In July 2012, Speedway acquired 10 convenience stores located in the northern Kentucky and southwestern Ohio regions from Road Ranger LLC in exchange for cash and a truck stop location in the Chicago metropolitan area. In connection with this acquisition, our Speedway segment recorded $5 million of goodwill.
	In May 2012, Speedway acquired 87 convenience stores situated throughout Indiana and Ohio from GasAmerica Services, Inc., along with the associated inventory, intangible assets and two parcels of undeveloped real estate. In connection with this acquisition, our Speedway segment recorded $83 million of goodwill.
	In May 2011, Speedway acquired 23 convenience stores in Indiana and Illinois. In connection with this acquisition, our Speedway segment recorded $9 million of goodwill.
	The goodwill associated with these acquisitions is deductible for income tax purposes.
	These acquisitions support our strategic initiative to increase our Speedway segment sales and profitablity. 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 ("TAEI"), which holds a 50 percent ownership in The Andersons Marathon Ethanol LLC ("TAME"), bringing our direct and indirect ownership interest in TAME to 67 percent; and a 40 percent interest in The Andersons Albion Ethanol LLC ("TAAE"), which owns an ethanol production facility in Albion, Michigan. On October 1, 2013, our ownership interest in TAAE increased to 43 percent as a result of TAAE acquiring one of the owner's interest. We hold a noncontrolling interest in each of these entities and account for them using the equity method of accounting since the minority owners have substantive participating rights.
	Investment in Pipeline
	During 2013, we made initial contributions of $24 million to acquire an ownership interest in North Dakota Pipeline Company LLC ("North Dakota Pipeline"). 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 in 2016. We will 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 25 for information on future contributions to North Dakota Pipeline.

Disposition

Disposition	12 Months Ended
	Dec. 31, 2013
Discontinued Operations and Disposal Groups [Abstract]	'
Disposition	'
	Disposition
	On December 1, 2010, we completed the sale of most of our Minnesota assets. These assets included the 74,000 barrel per calendar day St. Paul Park refinery and associated terminals, 166 convenience stores primarily branded SuperAmerica® (including six stores in Wisconsin), along with the SuperMom’s bakery (a baked goods and sandwich supply operation) and certain associated trademarks, SuperAmerica Franchising LLC, interests in pipeline assets in Minnesota and associated inventories. We refer to these assets as the “Minnesota Assets.” The refinery and terminal assets were part of our Refining & Marketing segment, the convenience stores and bakery were part of our Speedway segment, and the interests in pipeline assets were part of our Pipeline Transportation segment. This transaction value was approximately $935 million, which included approximately $330 million for inventories. We received $740 million in cash, net of closing costs, but prior to post-closing adjustments. The terms of the sale included (1) a preferred equity interest in the entity that holds the Minnesota Assets with a stated value of $80 million, (2) a maximum $125 million earnout provision payable to us over eight years, (3) a maximum $60 million of margin support payable to the buyer over two years, up to a maximum of $30 million per year, (4) a receivable from the buyer of $107 million which was fully collected in 2011, and (5) lease guarantees with a maximum exposure of $11 million made by us on behalf of and to the buyer related to a limited number of convenience store sites. As a result of this continuing involvement, the related gain on sale of $89 million was initially deferred.
	In July 2012, the buyer of our Minnesota Assets successfully completed an initial public offering (“IPO”). The successful completion of this IPO triggered the provisions in our May 4, 2012 settlement agreement with the buyer to be effective. Under the settlement agreement, we were released from our obligation to pay margin support and the buyer was released from its obligation to pay us under the earnout provision contained in the original sales agreement. Also, the buyer redeemed our $80 million preferred equity interest, paid us $12 million for dividends accrued on our preferred equity interest and paid us $40 million of cash, for total cash receipts of $132 million. In addition, the buyer issued us a new preferred security valued at $45 million. As a result, we recognized income before income taxes of approximately $183 million during 2012, which included $86 million of the deferred gain that was recorded when the sale transaction was originally closed.
	During 2013, the buyer redeemed the second preferred security for $49 million, which included $4 million of accrued distributions.
	We provided transition services to the buyer for approximately thirteen months following the sale. The buyer provided management and operational strategy for the business and we provided personnel to operate and maintain these Minnesota Assets.

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	Related Party Transactions
	Our related parties included:
	•	Marathon Oil Companies until June 30, 2011, the effective date of the Spinoff.
	•	TAAE, in which we have a 43 percent 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.
	•	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.
	We believe that transactions with related parties, other than certain administrative transactions with the Marathon Oil Companies to effect the Spinoff and related to the provision of services, were conducted on terms comparable to those with unaffiliated parties. See below for a description of transactions with the Marathon Oil Companies.
	On May 25, 2011, we entered into a separation and distribution agreement and several other agreements with the Marathon Oil Companies to effect the Spinoff and to provide a framework for our relationship with the Marathon Oil Companies. These agreements govern the relationship between us and Marathon Oil subsequent to the completion of the Spinoff and provide for the allocation between us and the Marathon Oil Companies of assets, liabilities and obligations attributable to periods prior to the Spinoff. Because the terms of these agreements were entered into in the context of a related party transaction, the terms may not be comparable to terms that would be obtained in a transaction between unaffiliated parties.
	The separation and distribution agreement between us and the Marathon Oil Companies contains the key provisions relating to the separation of our business from Marathon Oil and the distribution of our common stock to Marathon Oil stockholders. The separation and distribution agreement identifies the assets that were transferred or sold, liabilities that were assumed or sold and contracts that were assigned to us by the Marathon Oil Companies or by us to the Marathon Oil Companies in the Spinoff and describes how these transfers, sales, assumptions and assignments occurred. In accordance with the separation and distribution agreement, Marathon Oil determined that our aggregate cash and cash equivalents balance at June 30, 2011 should be approximately $1.625 billion. The separation and distribution agreement also contains provisions regarding the release of liabilities, indemnifications, insurance, nonsolicitation of employees, maintenance of confidentiality, payment of expenses and dispute resolution. See Note 25.
	We and Marathon Oil entered into a tax sharing agreement to govern the respective rights, responsibilities and obligations of Marathon Oil and us with respect to taxes and tax benefits, the filing of tax returns, the control of audits, restrictions on us to preserve the tax-free status of the Spinoff and other tax matters.
	We and Marathon Oil entered into an employee matters agreement providing that each company has responsibility for our own employees and compensation plans. The employee matters agreement also contains provisions regarding stock-based compensation. See Note 23.
	We entered into a transition services agreement with Marathon Oil under which we were providing each other with a variety of administrative services on an as-needed basis for a period of time not to exceed one year following the Spinoff. The charges under these transition service agreements were at cost-based rates that had been negotiated between us and Marathon Oil. Services provided to us by the Marathon Oil Companies included accounting, audit, treasury, tax, legal, information technology, administrative services, procurement of natural gas and health, environmental, safety and security. Services provided by us to the Marathon Oil Companies included legal, human resources, tax, accounting, audit, information technology and health, environmental, safety and security. The transition services agreement terminated on June 30, 2012.
	Sales to related parties were as follows:
	(In millions)	2013			2012		2011
	Equity method investees:
	Centennial	$	—		$	1	$	35
	Other equity method investees	8			7		7
	Marathon Oil Companies	—			—		13
	Total	$	8		$	8	$	55
	Related party sales to Centennial consist primarily of petroleum products. Related party sales to the Marathon Oil Companies consisted primarily of crude oil, which were based on contractual prices that were market-based, and pipeline operating revenue.
	The fees received for operating Centennial's pipeline, which are included in other income on the consolidated statements of income, were $1 million in both 2013 and 2012.
	Purchases from related parties were as follows:
	(In millions)	2013			2012		2011
	Equity method investees:
	Centennial	$	3		$	7	$	31
	LOOP	43			44		66
	TAAE	24			—		—
	TACE	130			73		46
	TAME	131			124		153
	Other equity method investees	26			32		30
	Marathon Oil Companies	—			—		1,590
	Total	$	357		$	280	$	1,916
	Related party purchases from Centennial consist primarily of refinery feedstocks and refined product transportation costs. Related party purchases from LOOP and other equity method investees consist primarily of crude oil transportation costs. Related party purchases from TAAE, TACE and TAME consist of ethanol. Related party purchases from the Marathon Oil Companies consisted primarily of crude oil and natural gas, which were recorded at contracted prices that were market-based.
	The Marathon Oil Companies performed certain services for us prior to the Spinoff such as executive oversight, accounting, treasury, tax, legal, procurement and information technology services. We also provided certain services to the Marathon Oil Companies prior to the Spinoff, such as legal, human resources and tax services. The two groups of companies charged each other for these shared services based on a rate that was negotiated between them. Where costs incurred by the Marathon Oil Companies on our behalf could not practically be determined by specific utilization, these costs were primarily allocated to us based on headcount or computer utilization. Our management believes those allocations were a reasonable reflection of the utilization of services provided. However, those allocations may not have fully reflected the expenses that would have been incurred had we been a stand-alone company during the periods presented. Net charges from the Marathon Oil Companies for these services reflected within selling, general and administrative expenses in the consolidated statements of income were $26 million for 2011.
	Receivables from related parties, which are included in receivables, less allowance for doubtful accounts on the consolidated balance sheets, were as follows:
		December 31,
	(In millions)	2013			2012
	Centennial	$	1		$	2
	TAME	1			—
	Total	$	2		$	2
	At December 31, 2013, we also had a $2 million long-term receivable from Centennial, which is included in other noncurrent assets on the consolidated balance sheet.
	Payables to related parties, which are included in accounts payable on the consolidated balance sheets, were as follows:
		December 31,
	(In millions)	2013			2012
	LOOP	$	3		$	4
	TAAE	2			—
	TACE	4			2
	TAME	5			5
	Other equity method investees	2			2
	Total	$	16		$	13
	We had a throughput and deficiency agreement with Centennial, which expired on March 31, 2012. During 2012, we impaired our $14 million prepaid tariff with Centennial. For additional information on the impairment, see Note 17.
	On July 18, 2007, we entered into a credit agreement with MOC Portfolio Delaware, Inc. (“PFD”), a subsidiary of Marathon Oil, providing for a $2.9 billion revolving credit facility which was scheduled to terminate on May 4, 2012. On October 28, 2010, we amended the credit agreement with PFD to increase the total amount available to $4.4 billion and extended the scheduled termination date to November 1, 2013. During 2011, we borrowed $7.75 billion and repaid $10.32 billion under the credit facility. The agreement was terminated on June 30, 2011, and there has been no subsequent activity. For U.S. Dollar loans under this credit facility, the interest rate was the higher of the prime rate or the sum of 0.5 percent, plus the federal funds rate. For Euro Dollar loans under this credit facility, the interest rate was based on LIBOR plus a margin ranging from 0.25 percent to 1.125 percent. The margin varied based on our usage and credit rating.
	On July 18, 2007, we entered into a $1.1 billion revenue bonds proceeds subsidiary loan agreement with Marathon Oil to finance a portion of our Garyville, Louisiana refinery major expansion project. Proceeds from the bonds were disbursed by Marathon Oil to us upon our request for reimbursement of expenditures related to the expansion. There were no borrowings in 2011. We repaid the $1.05 billion loan balance on February 1, 2011 and the loan was terminated effective April 1, 2011. The loan had an interest rate of 5.125 percent annually.
	In 2005, we entered into agreements with PFD to invest our excess cash. Such investments consisted of shares of PFD Redeemable Class A, Series 1 Preferred Stock (“PFD Preferred Stock”). We had the right to redeem all or any portion of the PFD Preferred Stock on any business day at $2,000 per share. Dividends on PFD Preferred Stock were declared and settled daily. All of our investments in PFD Preferred Stock were redeemed prior to the termination of this agreement on June 30, 2011.
	Related party net interest and other financial income for 2013 and 2012 was not material. Related party net interest and other financial income for 2011 was as follows:
	(In millions)	2011
	Dividend income:
	PFD Preferred Stock	$	35
	Interest expense:
	PFD revolving credit agreement	3
	Marathon Oil loan agreement	5
	Interest capitalized	(8		)
Total	—
Related party net interest and other financial income	$	35
We also recorded property, plant and equipment additions related to capitalized interest incurred by Marathon Oil on our behalf of $2 million in 2011, which were reflected as contributions from Marathon Oil.
Certain asset or liability transfers between us and Marathon Oil, including assets and liabilities contributed under the separation and distribution agreement related to the Spinoff, and certain expenses, such as stock-based compensation, incurred by Marathon Oil on our behalf were recorded as non-cash capital contributions or distributions. The net non-cash capital contributions from Marathon Oil were $57 million in 2011.

Income_per_Common_Share

Income per Common Share	12 Months Ended
	Dec. 31, 2013
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.
	On June 30, 2011, 356,337,127 shares of our common stock were distributed to Marathon Oil stockholders in conjunction with the Spinoff. For comparative purposes, and to provide a more meaningful calculation for weighted average shares, we have assumed this amount to be outstanding for periods prior to the Spinoff in the calculation of basic weighted average shares. In addition, for the dilutive weighted average share calculations, we have assumed the dilutive securities outstanding at June 30, 2011 were also outstanding for periods prior to the Spinoff. Excluded from the diluted share calculation are less than one million, approximately two million and approximately four million shares related to stock-based compensation awards in 2013, 2012 and 2011, respectively, 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.
	(In millions, except per share data)	2013		2012		2011
	Basic earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	2,112	$	3,389	$	2,389
	Income allocated to participating securities	4		6		4
	Income available to common stockholders - basic	$	2,108	$	3,383	$	2,385
	Weighted average common shares outstanding	315		340		356
	Basic earnings per share	$	6.69	$	9.95	$	6.7
	Diluted earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	2,112	$	3,389	$	2,389
	Income allocated to participating securities	4		6		4
	Income available to common stockholders - diluted	$	2,108	$	3,383	$	2,385
	Weighted average common shares outstanding	315		340		356
	Effect of dilutive securities	2		2		1
	Weighted average common shares, including dilutive effect	317		342		357
	Diluted earnings per share	$	6.64	$	9.89	$	6.67

Equity

Equity	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Equity	'
	Equity
	On February 1, 2012, we announced that our board of directors authorized a share repurchase plan, enabling us to purchase up to $2.0 billion of MPC common stock over a two-year period. On January 30, 2013, we announced that our board of directors approved an additional $2.0 billion share repurchase authorization to expire in December 2014. On September 26, 2013, we announced that our board of directors approved an additional $2.0 billion share repurchase authorization through September 2015, resulting in $6.0 billion of total share repurchase authorizations since January 1, 2012. After the effects of the accelerated share repurchase (“ASR”) programs and open market repurchases shown below, $1.86 billion of the amounts authorized by our board of directors remain available for repurchases at December 31, 2013. 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.
	In February 2012 and November 2012, we entered into $850 million and $500 million ASR programs, respectively, to repurchase shares of MPC common stock under the approved share repurchase plan authorized by our board of directors. The total number of shares repurchased under these ASR programs was based generally on the volume-weighted average price of our common stock during the repurchase periods. The shares repurchased under the ASR programs were accounted for as treasury stock purchase transactions, reducing the weighted average number of basic and diluted common shares outstanding by the shares repurchased, and as forward contracts indexed to our common stock. The forward contracts were accounted for as equity instruments.
	Total share repurchases transacted through ASR programs and open market transactions were as follows for the respective periods. There were no shares repurchased in 2011.
	(In millions, except per share data)	2013		2012
	Number of shares repurchased(a)	37		28
	Cash paid for shares repurchased	$	2,793	$	1,350
	Effective average cost per delivered share	$	76.14	$	46.73
	(a)	Shares repurchased in 2013 includes 1 million shares received under the November 2012 ASR program, which were paid for in 2012.
	As of December 31, 2013, the total number of shares we have repurchased cumulatively through the ASR programs and open market repurchases since February 2012 was 65 million shares at an average cost per share of $63.61. The cash paid for shares repurchased during this period was $4.14 billion. In addition, at December 31, 2013, we had agreements to acquire additional common shares for $12 million, which were settled in early January 2014.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2013
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, buyers on the spot market, 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 periods prior to the acquisition does not include amounts for these operations. See Note 5.
	Segment income represents income from operations attributable to the reportable segments. Corporate administrative expenses, including those allocated from the Marathon Oil Companies prior to the Spinoff, 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
	Year Ended December 31, 2013
	Revenues:
	Customer	$	85,608		$	14,471		$	79		$	100,158
	Intersegment(a)	9,294			4			458			9,756
	Related parties	8			—			—			8
	Segment revenues	94,910			14,475			537			109,922
	Elimination of intersegment revenues	(9,294		)	(4		)	(458		)	(9,756		)
	Total revenues	$	85,616		$	14,471		$	79		$	100,166
	Segment income from operations(b)	$	3,206		$	375		$	210		$	3,791
	Income from equity method investments	28			—			8			36
	Depreciation and amortization(c)	1,011			112			74			1,197
	Capital expenditures and investments(d)(e)(f)	2,094			296			234			2,624
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Year Ended December 31, 2012
	Revenues:
	Customer	$	67,921		$	14,239		$	77		$	82,237
	Intersegment(a)	8,782			4			381			9,167
	Related parties	7			—			1			8
	Segment revenues	76,710			14,243			459			91,412
	Elimination of intersegment revenues	(8,782		)	(4		)	(381		)	(9,167		)
	Total revenues	$	67,928		$	14,239		$	78		$	82,245
	Segment income from operations(b)	$	5,098		$	310		$	216		$	5,624
	Income (loss) from equity method investments	(6		)	—			32			26
	Depreciation and amortization(c)	804			114			54			972
	Capital expenditures and investments(d)(e)	705			340			211			1,256
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Year Ended December 31, 2011
	Revenues:
	Customer	$	65,028		$	13,490		$	65		$	78,583
	Intersegment(a)	8,301			—			335			8,636
	Related parties	52			—			3			55
	Segment revenues	73,381			13,490			403			87,274
	Elimination of intersegment revenues	(8,301		)	—			(335		)	(8,636		)
	Total revenues	$	65,080		$	13,490		$	68		$	78,638
	Segment income from operations	$	3,591		$	271		$	199		$	4,061
	Income from equity method investments	11			—			39			50
	Depreciation and amortization(c)	718			110			45			873
	Capital expenditures and investments(d)(e)	900			164			121			1,185
	(a)	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.
	(b)	Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other 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)	Includes Speedway’s acquisition of convenience stores. See Note 5.
	(f)	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 5.
	The following reconciles segment income from operations to income before income taxes as reported in the consolidated statements of income:
	(In millions)	2013			2012			2011
	Segment income from operations	$	3,791		$	5,624		$	4,061
	Items not allocated to segments:
	Corporate and other unallocated items(a)(b)	(271		)	(336		)	(316		)
	Minnesota Assets sale settlement gain(c)	—			183			—
	Pension settlement expenses(d)	(95		)	(124		)	—
	Net interest and other financial income (costs)(e)	(179		)	(109		)	(26		)
	Income before income taxes	$	3,246		$	5,238		$	3,719
	(a)	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses, including allocations from the Marathon Oil Companies for periods prior to the Spinoff, and costs related to certain non-operating assets.
	(b)	Corporate overhead costs attributable to MPLX were included in the Pipeline Transportation segment subsequent to MPLX’s October 31, 2012 initial public offering.
(c)	See Note 6.
(d)	See Note 22.
(e)	Includes related party net interest and other financial income.
The following reconciles segment capital expenditures and investments to total capital expenditures:
(In millions)	2013			2012			2011
Segment capital expenditures and investments	$	2,624		$	1,256		$	1,185
Less: Investments in equity method investees	124			28			11
Plus: Items not allocated to segments:
Capital expenditures not allocated to segments	137			103			24
Capitalized interest	28			101			114
Total capital expenditures(a)(b)	$	2,665		$	1,432		$	1,312
(a)	Capital expenditures include changes in capital accruals.
(b)	See Note 20 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 total revenues to sales and other operating revenues (including consumer excise taxes) as reported in the consolidated statements of income:
(In millions)	2013			2012			2011
Total revenues (as reported above)	$	100,166		$	82,245		$	78,638
Plus: Corporate and other unallocated items	(6		)	(2		)	—
Less: Sales to related parties	8			8			55
Sales and other operating revenues (including consumer excise taxes)	$	100,152		$	82,235		$	78,583
Revenues by product line were:
(In millions)	2013			2012			2011
Refined products	$	93,520		$	76,234		$	73,334
Merchandise	3,308			3,229			3,090
Crude oil and refinery feedstocks	2,988			2,514			1,972
Transportation and other	344			266			242
Total revenues	100,160			82,243			78,638
Less: Sales to related parties	8			8			55
Sales and other operating revenues (including consumer excise taxes)	$	100,152		$	82,235		$	78,583
Revenue from BP p.l.c. included in the Refining & Marketing segment represented 10 percent of our total annual revenues for the year ended December 31, 2013. No single customer accounted for more than 10 percent of annual revenues for the years ended December 31, 2012 and 2011.
We do not have significant operations in foreign countries. Therefore, revenues in foreign countries and long-lived assets located in foreign countries, including property, plant and equipment and investments, are not material to our operations.
Total assets by reportable segment were:
	December 31,
(In millions)	2013			2012
Refining & Marketing	$	19,573		$	17,052
Speedway	2,064			1,947
Pipeline Transportation	1,947			1,950
Corporate and Other	4,801			6,274
Total consolidated assets	$	28,385		$	27,223

Other_Items

Other Items	12 Months Ended
	Dec. 31, 2013
Other Income and Expenses [Abstract]	'
Other Items	'
	Other Items
	Net interest and other financial income (costs) was:
	(In millions)	2013			2012			2011
	Interest:
	Interest income	$	9		$	5		$	3
	Interest expense(a)	(195		)	(191		)	(164		)
	Interest capitalized(a)	28			101			104
	Total net interest	(158		)	(85		)	(57		)
	Other:
	Net foreign currency gains	—			—			12
	Bank service and other fees	(21		)	(25		)	(16		)
	Total other	(21		)	(25		)	(4		)
	Net interest and other financial income (costs)	$	(179	)	$	(110	)	$	(61	)
	(a)	See Note 7 for information on related party interest expense and capitalized interest.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	Income tax provisions (benefits) were:
		2013											2012							2011
	(In millions)	Current				Deferred				Total			Current			Deferred		Total		Current		Deferred			Total
	Federal	$	954			$	20			$	974		$	1,185		$	432	$	1,617	$	1,040	$	139		$	1,179
	State and local	131				8				139			169			57		226		152		(16		)	136
	Foreign	5				(5		)		—			(1		)	3		2		15		—			15
	Total	$	1,090			$	23			$	1,113		$	1,353		$	492	$	1,845	$	1,207	$	123		$	1,330
	The provision for income taxes for periods prior to the Spinoff have been computed as if we were a stand-alone company.
	A reconciliation of the federal statutory income tax rate (35 percent) applied to income before income taxes to the provision for income taxes follows:
		2013			2012			2011
	Statutory rate applied to income before income taxes	35	%		35	%		35	%
	State and local income taxes, net of federal income tax effects	3			2			2
	Domestic manufacturing deduction	(2	)		(1	)		(1	)
	Other	(2	)		(1	)		—
	Provision for income taxes	34	%		35	%		36	%
	Deferred tax assets and liabilities resulted from the following:
		December 31,
	(In millions)	2013				2012
	Deferred tax assets:
	Employee benefits	$	483			$	585
	Environmental	37				35
	Other	49				55
	Total deferred tax assets	569				675
	Deferred tax liabilities:
	Property, plant and equipment	2,290				2,225
	Inventories	614				610
	Investments in subsidiaries and affiliates	267				307
	Other	70				29
	Total deferred tax liabilities	3,241				3,171
	Net deferred tax liabilities	$	2,672			$	2,496
	Net deferred tax liabilities were classified in the consolidated balance sheets as follows:
		December 31,
	(In millions)	2013				2012
	Assets:
	Other noncurrent assets	$	2			$	—
	Liabilities:
	Accrued taxes	370				446
	Deferred income taxes	2,304				2,050
	Net deferred tax liabilities	$	2,672			$	2,496
	The ability to realize the benefit of foreign tax credits is based on certain estimates concerning future financial conditions, income generated from foreign sources and our tax profile in the years that such credits may be claimed. A federal valuation allowance was established in 2013 for $2 million due to changes in the expected realizability of foreign tax credits.
	MPC was a new taxpayer beginning in 2011. Prior to 2011, MPC was included in the Marathon Oil federal income tax returns for applicable years. MPC is continuously undergoing examination of its U.S. federal income tax returns by the Internal Revenue Service. Such audits have been completed through the 2009 tax year. We believe adequate provision has been made for federal income taxes and interest which may become payable for years not yet settled. Further, we are routinely involved in U.S. state income tax audits. We believe all other audits will be resolved with the amounts paid and/or provided for these liabilities. As of December 31, 2013, our income tax returns remain subject to examination in the following major tax jurisdictions for the tax years indicated:
	United States Federal	2010	-	2012
	States	2004	-	2012
	As a result of the Spinoff and pursuant to the tax sharing agreement by Marathon Oil and MPC, the unrecognized tax benefits related to MPC operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and MPC has indemnified Marathon Oil. Before the Spinoff, MPC made a prepayment of a portion of the unrecognized tax benefits to Marathon Oil, which is reflected in the table below as settlements. See Note 25. During 2013, we settled with Marathon Oil our U.S. federal and related state return liabilities for the 2008-2009 tax years, resulting in a reduction in unrecognized tax benefits of $21 million, which are also reflected in the table below as settlements.
	During 2013, we settled with Marathon Oil for the 2011 period prior to the spinoff based on filed tax returns and in accordance with the tax sharing agreement, resulting in a $39 million increase to additional paid-in capital.
	The following table summarizes the activity in unrecognized tax benefits:
	(In millions)	2013				2012				2011
	January 1 balance	$	40			$	20			$	14
	Additions for tax positions of prior years	30				32				50
	Reductions for tax positions of prior years	(25		)		(6		)		—
	Settlements	(30		)		(6		)		(44		)
	Statute of limitations	(2		)		—				—
	December 31 balance	$	13			$	40			$	20
	If the unrecognized tax benefits as of December 31, 2013 were recognized, $6 million would affect our effective income tax rate. There were $5 million of uncertain tax positions as of December 31, 2013 for which it is reasonably possible that the amount of unrecognized tax benefits would significantly increase or decrease during the next twelve months.
	Interest and penalties related to income taxes are recorded as part of the provision for income taxes. Such interest and penalties were net receipts (expenses) of ($11 million), $1 million and ($5 million) in 2013, 2012 and 2011. As of December 31, 2013 and 2012, $15 million and $9 million of interest and penalties were accrued related to income taxes.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2013
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
		December 31,
	(In millions)	2013		2012
	Crude oil and refinery feedstocks	$	1,797	$	1,383
	Refined products	2,367		1,761
	Materials and supplies	425		231
	Merchandise	100		74
	Total (at cost)	$	4,689	$	3,449
	The LIFO method accounted for 90 percent and 93 percent of total inventory value at December 31, 2013 and 2012, respectively. Current acquisition costs were estimated to exceed the LIFO inventory value at December 31, 2013 and 2012 by $4,084 million and $4,511 million, respectively. There were no liquidations of LIFO inventories in 2013 and 2012. Cost of revenues decreased and income from operations increased by $4 million in 2011 as a result of liquidations of LIFO inventories, excluding inventories liquidated in dispositions.

Equity_Method_Investments

Equity Method Investments	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Equity Method Investments	'
	Equity Method Investments
		Ownership as of December 31, 2013		December 31,
	(In millions)			2013				2012
	Centennial	50%		$	29			$	27
	LOCAP LLC	59%		24				26
	LOOP	51%		214				198
	North Dakota Pipeline(a)	38%		24				—
	TAAE	43%		29				—
	TACE	60%		70				29
	TAEI	34%		23				—
	TAME(b)	50%		35				27
	Other			15				14
	Total			$	463			$	321
	(a)	We own a 38 percent interest in the Class B units of this entity. Our Class B units will be converted to an approximate 27 percent ownership interest in the Class A units of this entity upon completion of the Sandpiper pipeline construction project in 2016.
	(b)	Excludes TAEI's investment in TAME.
	Summarized financial information for equity method investees is as follows:
	(In millions)	2013				2012				2011
	Income statement data:
	Revenues and other income	$	1,067			$	1,025			$	1,043
	Income from operations	87				73				128
	Net income	63				47				101
	Balance sheet data - December 31:
	Current assets	$	339			$	217
	Noncurrent assets	1,238				1,163
	Current liabilities	145				161
	Noncurrent liabilities	618				636
	As of December 31, 2013, the carrying value of our equity method investments was $41 million higher than the underlying net assets of investees. This basis difference is being amortized or accreted into net income over the remaining estimated useful lives of the underlying net assets, except for $55 million of excess related to goodwill.
	Centennial experienced a significant reduction in shipment volumes in the second half of 2011 that has continued through 2013. At December 31, 2013, Centennial was not shipping product. As a result, we continued to evaluate the carrying value of our equity investment in Centennial and concluded that no impairment was required given our assessment of its fair value based on various potential uses of Centennial’s assets. If current business conditions remain unchanged and the owners of Centennial are unable to find an alternative use for the assets, there could be a future impairment of our Centennial interest. As of December 31, 2013, our equity investment in Centennial was $29 million and we had a $42 million guarantee associated with 50 percent of Centennial's outstanding debt. See Note 25 for additional information on the debt guarantee.
	Dividends and partnership distributions received from equity method investees (excluding distributions that represented a return of capital previously contributed) were $18 million, $37 million and $48 million in 2013, 2012 and 2011.

Property_Plant_and_Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Property, Plant and Equipment	'
	Property, Plant and Equipment
	(In millions)	Estimated	December 31,
		Useful Lives	2013		2012
	Refining & Marketing	4 - 25 years	$	16,982	$	15,089
	Speedway	4 - 15 years	2,344		2,100
	Pipeline Transportation	16 - 42 years	1,921		1,747
	Corporate and Other	4 - 40 years	546		473
	Total		21,793		19,409
	Less accumulated depreciation		7,872		6,766
	Property, plant and equipment, net		$	13,921	$	12,643
	Property, plant and equipment includes gross assets acquired under capital leases of $510 million and $417 million at December 31, 2013 and 2012, with related amounts in accumulated depreciation of $111 million and $79 million at December 31, 2013 and 2012. Property, plant and equipment includes construction in progress of $747 million and $520 million at December 31, 2013 and 2012, which primarily relates to refinery projects.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill	'
	Goodwill
	Goodwill is tested for impairment on an annual basis and when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below the carrying value. We performed our annual impairment tests for 2013 and 2012, and no impairment was required.
	The changes in the carrying amount of goodwill for 2013 and 2012 were as follows:
	(In millions)	Refining & Marketing		Speedway		Pipeline		Total
						Transportation
	2012
	Beginning balance	$	551	$	129	$	162	$	842
	Acquisitions(a)	—		88		—		88
	Ending balance	$	551	$	217	$	162	$	930
	2013
	Beginning balance	$	551	$	217	$	162	$	930
	Acquisitions(a)	—		8		—		8
	Ending balance	$	551	$	225	$	162	$	938
	(a)	See Note 5 for information on the acquisitions.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2013
Text Block [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 December 31, 2013 and 2012 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.
		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	$	—
		December 31, 2012
		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	$	49		$	—		$	—		$	(49	)	$	—	$	45
	Other assets	2			—			—			N/A			2		—
	Total assets at fair value	$	51		$	—		$	—		$	(49	)	$	2	$	45
	Commodity derivative instruments, liabilities	$	88		$	—		$	—		$	(88	)	$	—	$	—
	(a)	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of December 31, 2013 and 2012, cash collateral of $32 million and $39 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 $159 million classified as current.
	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 December 31, 2013 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 5. 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 net beginning and ending balances recorded for net assets/(liabilities) classified as Level 3 in the fair value hierarchy.
	(In millions)	2013			2012			2011
	Beginning balance	$	—		$	—		$	2,402
	Contingent consideration agreement	(600		)	—			—
	Total realized and unrealized losses included in net income	(25		)	(2		)	—
	Purchases of PFD Preferred Stock(a)	—			—			10,326
	Redemptions of PFD Preferred Stock(a)	—			—			(12,730		)
	Settlements of derivative instruments	—			2			2
	Ending balance	$	(625	)	$	—		$	—
	(a)	For information on PFD Preferred Stock, see Note 7. The fair value of our PFD Preferred Stock investment was measured using an income approach since the securities were not publicly traded; therefore, they were classified as Level 3 in the fair value hierarchy.
	We did not hold any Level 3 derivative instruments during 2013 and 2012. Net income for 2011 included unrealized losses of less than $1 million related to Level 3 derivative instruments held during 2011. See Note 18 for the income statement impacts of our derivative instruments. There was an unrealized loss of $25 million in 2013 related to the contingent consideration agreement.
	Fair Values – Nonrecurring
	The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition.
		Year Ended December 31,
		2013						2012						2011
	(In millions)	Fair Value			Impairment			Fair Value			Impairment			Fair Value		Impairment
	Property, plant and equipment, net	$	1		$	8		$	—		$	—		$	—	$	—
	Other noncurrent assets	—			—			—			14			—		—
	Due to changing market conditions, we assessed one of our light products terminals for impairment. The terminal is operated by our Refining & Marketing segment. We recorded an impairment charge of $8 million for this terminal in 2013. The impairment is included in depreciation and amortization on the consolidated statements of income. The fair value of the terminal was measured using a market approach based on comparable area property values which are Level 3 inputs.
	As a result of changing market conditions and declining throughput volumes, we impaired our Refining & Marketing segment’s prepaid tariff with Centennial by $14 million in 2012. The fair value measurement of the prepaid tariff was based on the income approach utilizing the probability of shipping sufficient volumes on Centennial’s pipeline over the remaining life of the throughput and deficiency credits, which expire March 31, 2014 if not utilized. This measurement is classified as Level 3.
	Fair Values – Reported
	The following table summarizes financial instruments on the basis of their nature, characteristics and risk at December 31, 2013 and 2012, excluding the derivative financial instruments and contingent consideration reported above.
		December 31,
		2013						2012
	(In millions)	Fair Value			Carrying			Fair Value			Carrying
					Value						Value
	Financial assets:
	Investments	$	336		$	14		$	263		$	59
	Other	31			30			33			31
	Total financial assets	$	367		$	44		$	296		$	90
	Financial liabilities:
	Long-term debt(a)	$	3,306		$	3,001		$	3,559		$	3,006
	Deferred credits and other liabilities	21			21			23			23
	Total financial liabilities	$	3,327		$	3,022		$	3,582		$	3,029
	(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 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.

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Derivatives	'
	Derivatives
	For further information regarding the fair value measurement of derivative instruments, including any effect of master netting agreements or collateral, see Note 17. See Note 2 for a discussion of the types of derivatives we use and the reasons for them. We do not designate any of our commodity derivative instruments as hedges for accounting purposes. Our interest rate derivative instruments were designated as fair value accounting hedges.
	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 December 31, 2013 and 2012:
		31-Dec-13
	(In millions)	Asset				Liability				Balance Sheet Location
	Commodity derivatives	$	21			$	53			Other current assets
		31-Dec-12
	(In millions)	Asset				Liability				Balance Sheet Location
	Commodity derivatives	$	49			$	88			Other current assets
	Derivatives Designated as Fair Value Accounting Hedges
	In 2012, we terminated interest rate swap agreements with a notional amount of $500 million that had been entered into as fair value accounting hedges on our 3.50 percent senior notes due in March 2016. There was a $20 million gain on the termination of the transactions, which has been accounted for as an adjustment to our long-term debt balance. The gain is being amortized over the remaining life of the 3.50 percent senior notes, which reduces our interest expense. The interest rate swaps had no accounting hedge ineffectiveness.
	The following table summarizes the pretax effect of derivative instruments designated as accounting hedges of fair value in our consolidated statements of income:
				Gain (Loss)
	(In millions)	Income Statement Location		2013				2012				2011
	Derivative
	Interest rate	Net interest and other financial income (costs)		$	—			$	1			$	19
	Hedged Item
	Long-term debt	Net interest and other financial income (costs)		$	—			$	(1	)		$	(19	)
	Derivatives not Designated as Accounting Hedges
	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 table below summarizes open commodity derivative contracts for crude oil and refined products as of December 31, 2013.
		Position		Total Barrels
				(In thousands)
	Crude oil(a)
	Exchange-traded	Long		10,580
	Exchange-traded	Short		-23,900
	Refined Products(a)
	Exchange-traded	Long		3,646
	Exchange-traded	Short		-4,175
	(a)100 percent of these contracts expire in the first quarter of 2014.
	The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income:
	(In millions)	Gain (Loss)
	Income Statement Location	2013				2012				2011
	Sales and other operating revenues	$	12			$	8			$	(34	)
	Other income	—				—				1
	Cost of revenues	(180		)		65				182
	Total	$	(168	)		$	73			$	149

Debt

Debt	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Debt	'
	Debt
	Our outstanding borrowings at December 31, 2013 and 2012 consisted of the following:
		December 31,
	(In millions)	2013			2012
	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	395			355
	MPLX Operations LLC revolving credit agreement due 2017	—			—
	Trade receivables securitization facility due 2016	—			—
	Total	3,395			3,355
	Unamortized discount	(10		)	(10		)
	Fair value adjustments(a)	11			16
	Amounts due within one year	(23		)	(19		)
	Total long-term debt due after one year	$	3,373		$	3,342
	(a)	See Notes 17 and 18 for information on interest rate swaps.
	The following table shows five years of scheduled debt payments.
	(In millions)
	2014	$	23
	2015	27
	2016	777
	2017	28
	2018	30
	There were no borrowings or letters of credit outstanding under the revolving credit agreements or the trade receivable securitization facility at December 31, 2013.
	MPC Revolving Credit Agreement - We have a $2.5 billion unsecured revolving credit agreement ("Credit Agreement") in place with a maturity date of September 14, 2017. The Credit Agreement includes letter of credit issuing capacity of up to $2.0 billion and swingline loan capacity of up to $100 million. We may increase our borrowing capacity under the Credit Agreement by up to an additional $500 million, subject to certain conditions including the consent of the lenders whose commitments would be increased. In addition, the maturity date may be extended for up to two additional one-year periods subject to the approval of lenders holding greater than 50 percent of the commitments then outstanding, provided that the commitments of any non-consenting lenders will be terminated on the then-effective maturity date.
	Borrowings under the Credit Agreement bear interest at either the Adjusted LIBO Rate (as defined in the Credit Agreement) plus a margin or the Alternate Base Rate (as defined in the Credit Agreement) plus a margin. We are charged various fees and expenses in connection with the Credit Agreement, including administrative agent fees, commitment fees on the unused portion of our borrowing capacity and fees related to issued and outstanding letters of credit. The applicable interest rates and certain of the fees fluctuate based on the credit ratings in effect from time to time on our long-term debt.
	The Credit Agreement contains certain representations and warranties, affirmative and restrictive covenants and events of default that we consider to be usual and customary for arrangements of this type, including a financial covenant that requires us to maintain a ratio of Consolidated Net Debt (as defined in the Credit Agreement) to Total Capitalization (as defined in the Credit Agreement) of no greater than 0.65 to 1.00 as of the last day of each fiscal quarter. Other covenants, among other things, restrict our ability to incur debt, create liens on our assets or enter into transactions with affiliates. As of December 31, 2013, we were in compliance with the covenants contained in the Credit Agreement.
	MPLX Operations LLC Revolving Credit Agreement - MPLX Operations LLC, an affiliate of MPC and wholly-owned subsidiary of MPLX LP, has a $500 million unsecured revolving credit agreement ("MPLX Credit Agreement") in place with a maturity date of October 31, 2017. The MPLX Credit Agreement includes letter of credit issuing capacity of up to $250 million and swingline loan capacity of up to $50 million. The borrowing capacity under the MPLX Credit Agreement may be increased by up to an additional $300 million, subject to certain conditions, including the consent of the lenders whose commitments would increase. In addition, the maturity date may be extended up to two additional one-year periods subject to the approval of lenders holding greater than 50 percent of the commitments then outstanding, provided that the commitments of any non-consenting lenders will be terminated on the then-effective maturity date.
	Borrowings under the MPLX Credit Agreement bear interest at either the Adjusted LIBO Rate (as defined in the MPLX Credit Agreement) plus a margin, or the Alternate Base Rate (as defined in the MPLX Credit Agreement) plus a margin. MPLX is charged various fees and expenses in connection with the agreement, including administrative agent fees, commitment fees on the unused portion of the borrowing capacity and fees with respect to issued and outstanding letters of credit. The applicable interest rates and certain of the fees fluctuate based on MPLX's ratio of Consolidated Total Debt (as defined in the MPLX Credit Agreement) as of the end of each fiscal quarter to Consolidated EBITDA (as defined in the MPLX Credit Agreement) for the prior four fiscal quarters, or the credit ratings in effect from time to time on MPLX's long-term debt subsequent to the Rating Date (as defined in the MPLX Credit Agreement).
	The MPLX Credit Agreement includes certain representations and warranties, affirmative and restrictive covenants and events of default that we consider to be usual and customary for an agreement of this type, including a financial covenant that requires MPLX to maintain a ratio of Consolidated Total Debt as of the end of each fiscal quarter to Consolidated EBITDA for the prior four fiscal quarters of no greater than 5.0 to 1.0 (or 5.5 to 1.0 during the six-month period following certain acquisitions). Other covenants restrict MPLX from incurring debt, creating liens on its assets and entering into transactions with affiliates. As of December 31, 2013, MPLX was in compliance with the covenants contained in the MPLX Credit Agreement.
	Trade receivables securitization facility - On December 18, 2013, we entered into a three-year, $1.3 billion trade receivables securitization facility with a group of financial institutions that act as committed purchasers, conduit purchasers, letter of credit issuers and managing agents under the facility. The facility is evidenced by a Receivables Purchase Agreement and a Second Amended and Restated Receivables Sale Agreement and replaces the previously existing accounts receivable facility that was set to expire on June 30, 2014.
	The facility consists of one of our wholly-owned subsidiaries, Marathon Petroleum Company LP (“MPC LP”), selling or contributing on an on-going basis all of its trade receivables (including trade receivables acquired from Marathon Petroleum Trading Canada LLC, a wholly-owned subsidiary of MPC LP), together with all related security and interests in the proceeds thereof, without recourse, to another wholly-owned, bankruptcy-remote special purpose subsidiary, MPC Trade Receivables Company LLC (“TRC”), in exchange for a combination of cash, equity or a subordinated note issued by TRC to MPC LP. TRC, in turn, has the ability to finance its purchase of the receivables from MPC LP by selling undivided ownership interests in qualifying trade receivables, together with all related security and interests in the proceeds thereof, without recourse, to the purchasing group in exchange for cash proceeds. The facility also provides for the issuance of letters of credit of up to an initial amount of $1.25 billion, provided that the aggregate credit exposure of the purchasing group is limited to no more than $1.3 billion at any one time.
	To the extent that TRC retains an ownership interest in the receivables it has purchased or received from MPC LP, such interest will be included in our consolidated financial statements solely as a result of the consolidation of the financial statements of TRC with those of MPC. The receivables sold or contributed to TRC are available first and foremost to satisfy claims of the creditors of TRC and are not available to satisfy the claims of creditors of MPC. TRC has granted a security interest in all of its assets to the purchasing group to secure its obligations under the Receivables Purchase Agreement.
	Proceeds from the sale of undivided percentage ownership interests in qualifying receivables under the facility will be reflected as debt on our consolidated balance sheet, none of which was outstanding as of December 31, 2013. We will remain responsible for servicing the receivables sold to the purchasing group. TRC pays floating-rate interest charges and usage fees on amounts outstanding under the facility, if any, and certain other fees related to the administration of the facility and letters of credit that are issued and outstanding under the facility.
	The Receivables Purchase Agreement and Second Amended and Restated Receivables Sale Agreement include representations and covenants that we consider usual and customary for arrangements of this type. Trade receivables are subject to customary criteria, limits and reserves before being deemed to qualify for sale by TRC pursuant to the facility. In addition, further purchases of qualified trade receivables under the facility are subject to termination, and TRC may be subject to default fees, upon the occurrence of certain amortization events that are included in the Receivables Purchase Agreement, which we consider to be usual and customary for arrangements of this type.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Supplemental Cash Flow Information	'
	Supplemental Cash Flow Information
	(In millions)	2013			2012			2011
	Net cash provided by operating activities included:
	Interest paid (net of amounts capitalized)	$	161		$	67		$	5
	Net income taxes paid to taxing authorities(a)	1,099			1,211			617
	Non-cash investing and financing activities:
	Capital lease obligations increase	$	61		$	62		$	26
	Property, plant and equipment contributed by Marathon Oil	—			—			81
	Property, plant and equipment sold	43			—			—
	Preferred equity interest received in contract settlement(b)	—			45			—
	Preferred equity interest dividend received in-kind	—			1			—
	Acquisitions:
	Contingent consideration(c)	600			—			—
	Payable to seller(c)	6			—			—
	Intangible asset acquired	—			3			—
	Liability assumed	—			2			—
	(a)	U.S. and most state income taxes, if incurred, were paid by Marathon Oil for periods prior to the Spinoff. The amount for 2012 includes payments of $181 million for 2011 return period income taxes made to Marathon Oil under our tax sharing agreement, and in return we received an equal amount of tax credits. See Note 25.
	(b)	See Note 6.
	(c)	See Note 5.
	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:
	(In millions)	2013			2012			2011
	Additions to property, plant and equipment	$	1,206		$	1,369		$	1,185
	Acquisitions(a)	1,386			180			74
	Increase (decrease) in capital accruals	73			(117		)	53
	Total capital expenditures	$	2,665		$	1,432		$	1,312
	(a)	Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The 2012 acquisitions exclude the inventory acquired and liability assumed. See Note 5.
	The following is a reconciliation of distributions to Marathon Oil:
	(In millions)	2011
	Distributions to Marathon Oil per consolidated statements of cash flows	$	(783	)
	Non-cash contributions from Marathon Oil(a)	57
	Distributions to Marathon Oil per consolidated statements of equity / net investment	$	(726	)
	(a)	See Note 7.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2013
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 (loss) before reclassifications	198			(13		)	—		4			189
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(45		)	(4		)	—		—			(49		)
	– actuarial loss(a)	66			3			—		—			69
	– settlement loss(a)	95			—			—		—			95
	Other(b)	—			—			—		(1		)	(1		)
	Tax expense	(43		)	—			—		—			(43		)
	Other comprehensive income (loss)	271			(14		)	—		3			260
	Balance as of December 31, 2013	$	(161	)	$	(50	)	$	4	$	3		$	(204	)
	(a)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 22.
	(b)	This amount was reclassified out of accumulated other comprehensive loss and is included in selling, general and administrative expenses on the consolidated statements of income.

Defined_Benefit_Pension_and_Ot

Defined Benefit Pension and Other Postretirement Plans	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Defined Benefit Pension and Other Postretirement Plans	'
	Defined Benefit Pension and Other Postretirement Plans
	We have noncontributory defined benefit pension plans covering substantially all employees. Benefits under these plans have been based primarily on age, years of service and final average pensionable earnings. The years of service component of this formula was frozen as of December 31, 2009. Benefits for service beginning January 1, 2010 are based on a cash balance formula with an annual percentage of eligible pay credited based upon age and years of service. Eligible Speedway employees accrue benefits under a defined contribution plan for service years beginning January 1, 2010.
	We also have other postretirement benefits covering most employees. Health care benefits are provided through comprehensive hospital, surgical and major medical benefit provisions subject to various cost-sharing features. Retiree life insurance benefits are provided to a closed group of retirees. Other postretirement benefits are not funded in advance.
	Due to the Galveston Bay Refinery and Related Assets acquisition during 2013, we remeasured certain pension and retiree medical plans resulting in a $122 million decrease in liabilities. The decrease in liabilities was due to a 0.2 percent increase in discount rates and an increase in pension plan asset value from December 31, 2012 to the remeasurement date. The net periodic benefit costs for 2013 reflect these remeasurements. The purchase accounting for the Galveston Bay Refinery and Related Assets acquisition includes a $43 million liability related to retiree medical assumed at the acquisition date. See Note 5.
	On May 17, 2012, we communicated to our employees changes in the defined benefit pension plans for Speedway and the legacy portion of the Marathon Petroleum Retirement Plan effective January 1, 2013. Final average pensionable earnings used to calculate pension benefits under these plans were fixed as of December 31, 2012. In addition, cap protection was added to limit potential annual lump sum distribution discount rate increases. These plan amendments resulted in an overall decrease in pension liabilities of approximately $537 million, with the offset primarily to other comprehensive income, which was recorded in 2012. The benefit of this liability reduction is being amortized into income through 2024.
	On August 20, 2012, we communicated, to our impacted Medicare eligible retirees, changes in the post-65 medical plan coverage of the Marathon Petroleum Health Plan and the Marathon Petroleum Retiree Health Plan. Effective January 1, 2013, these Medicare eligible participants now receive a tax free contribution to a health reimbursement account, which replaces benefits provided under the previous plans. Increases are capped at four percent per year. This plan change resulted in a reduction in retiree medical liabilities of $40 million. This was more than offset by an increase in retiree medical liabilities of approximately $57 million primarily due to a reduction in discount rates as of the remeasurement date. The overall net liability increase and the offset to other comprehensive income were recorded in 2012.
	Obligations and funded status – The accumulated benefit obligation for all defined benefit pension plans was $1,912 million and $2,035 million as of December 31, 2013 and 2012.
	The following summarizes our defined benefit pension plans that have accumulated benefit obligations in excess of plan assets.
		December 31,
	(In millions)	2013				2012
	Projected benefit obligations	$	1,927			$	2,192
	Accumulated benefit obligations	1,912				2,035
	Fair value of plan assets	1,800				1,478
	The following summarizes the projected benefit obligations and funded status for our defined benefit pension and other postretirement plans:
		Pension Benefits								Other Benefits
	(In millions)	2013				2012				2013			2012
	Change in benefit obligations:
	Benefit obligations at January 1	$	2,192			$	2,685			$	591		$	551
	Service cost	93				66				25			20
	Interest cost	73				94				26			24
	Actuarial (gain) loss	(183		)		117				17			53
	Benefits paid	(248		)		(233		)		(20		)	(17		)
	Liability gain due to curtailment	—				(17		)		—			—
	Other(a)	—				(520		)		48			(40		)
	Benefit obligations at December 31	1,927				2,192				687			591
	Change in plan assets:
	Fair value of plan assets at January 1	1,478				1,423				—			—
	Actual return on plan assets	241				157				—			—
	Employer contributions	329				131				—			—
	Benefits paid from plan assets	(248		)		(233		)		—			—
	Fair value of plan assets at December 31	1,800				1,478				—			—
	Funded status of plans at December 31	$	(127	)		$	(714	)		$	(687	)	$	(591	)
	Amounts recognized in the consolidated balance sheets:
	Current liabilities	$	(18	)		$	(18	)		$	(25	)	$	(21	)
	Noncurrent liabilities	(109		)		(696		)		(662		)	(570		)
	Accrued benefit cost	$	(127	)		$	(714	)		$	(687	)	$	(591	)
	Pretax amounts recognized in accumulated other comprehensive loss:(b)
	Net loss	$	668			$	1,147			$	107		$	93
	Prior service credit	(415		)		(460		)		(30		)	(38		)
	(a)	Includes adjustments related to plan amendments in 2013 and 2012. Also, includes adjustments related to the Galveston Bay Refinery and Related Assets acquisition in 2013.
	(b)	Amounts exclude those related to LOOP, an equity method investee with defined benefit pension and postretirement plans for which net losses of $16 million and $2 million were recorded in accumulated other comprehensive loss in 2013, reflecting our 51 percent share.
	Components of net periodic benefit cost and other comprehensive loss – The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive loss for our defined benefit pension and other postretirement plans.
		Pension Benefits											Other Benefits
	(In millions)	2013				2012				2011			2013				2012			2011
	Components of net periodic benefit cost:
	Service cost	$	93			$	66			$	65		$	25			$	20		$	19
	Interest cost	73				94				110			26				24			27
	Expected return on plan assets	(107		)		(104		)		(97		)	—				—			—
	Amortization – prior service cost (credit)	(45		)		(18		)		6			(4		)		(2		)	—
	– actuarial loss	66				93				71			3				2			—
	– net settlement/curtailment loss(a)	95				125				8			—				—			—
	Net periodic benefit cost(b)	$	175			$	256			$	163		$	50			$	44		$	46
	Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):
	Actuarial (gain) loss	$	(317	)		$	46			$	427		$	17			$	53		$	39
	Prior service cost (credit)(c)	—				(520		)		—			4				(40		)	—
	Amortization of actuarial loss	(161		)		(218		)		(79		)	(3		)		(2		)	—
	Amortization of prior service cost (credit)	45				18				(6		)	4				2			—
	Other(d)	—				—				6			—				—			—
	Total recognized in other comprehensive loss	$	(433	)		$	(674	)		$	348		$	22			$	13		$	39
	Total recognized in net periodic benefit cost and other comprehensive loss	$	(258	)		$	(418	)		$	511		$	72			$	57		$	85
	(a)	A curtailment gain was recorded in 2011 on the Speedway pension plan at the end of the transition services period related to the sale of most of our Minnesota Assets in 2010. See Note 6.
	(b)	Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
	(c)	Includes adjustments due to plan amendments approved in 2013 and adjustments due to changes made to the defined pension plans and the post-65 medical plan coverage effective January 1, 2013.
(d)	Includes adjustments related to the Spinoff in 2011.
Lump sum payments to employees retiring in 2013, 2012 and 2011 exceeded the plan’s total service and interest costs expected for those years. Settlement losses are required to be recorded when lump sum payments exceed total service and interest costs. As a result, pension settlement expenses were recorded in 2013, 2012 and 2011 related to our cumulative lump sum payments made during those years.
The estimated net gain/loss and prior service credit for our defined benefit pension plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2014 are $52 million and $46 million. The 2014 net loss amortization is expected to be lower than the 2013 actual amortization primarily as a result of adjustments made to the net loss balance due to settlement accounting in 2013. The estimated net loss and prior service credit for our other defined benefit postretirement plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2014 is $3 million and $4 million, respectively.
Plan assumptions – The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2013, 2012 and 2011.
	Pension Benefits									Other Benefits
	2013			2012			2011			2013		2012			2011
Weighted-average assumptions used to determine benefit obligation:
Discount rate	4.3	%		3.45	%		4.3	%		4.95	%	4.05	%		4.65	%
Rate of compensation increase	3.7	%		5	%		5	%		3.7	%	5	%		5	%
Weighted-average assumptions used to determine net periodic benefit cost:
Discount rate	3.88	%		4.06	%		4.98	%		4.11	%	4.54	%		5.55	%
Expected long-term return on plan assets(a)	7.5	%		7.5	%		8.5	%		—	%	—	%		—	%
Rate of compensation increase	5	%		5	%		5	%		5	%	5	%		5	%
(a)	Effective January 1, 2014, the expected long-term rate of return on plan assets changed from 7.50 percent to 7.00 percent due to a change in our plan investment strategy.
Expected long-term return on plan assets
The overall expected long-term return on plan assets assumption is determined based on an asset rate-of-return modeling tool developed by a third-party investment group. The tool utilizes underlying assumptions based on actual returns by asset category and inflation and takes into account our asset allocation to derive an expected long-term rate of return on those assets. Capital market assumptions reflect the long-term capital market outlook. The assumptions for equity and fixed income investments are developed using a building-block approach, reflecting observable inflation information and interest rate information available in the fixed income markets. Long-term assumptions for other asset categories are based on historical results, current market characteristics and the professional judgment of our internal and external investment teams.
Assumed health care cost trend
The following summarizes the assumed health care cost trend rates.
	December 31,
	2013			2012			2011
Health care cost trend rate assumed for the following year:
Medical:
Pre-65	8	%		8	%		7.5	%
Post-65(a)	N/A			N/A			7	%
Prescription drugs	7	%		7	%		7.5	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate):
Medical:
Pre-65	5	%		5	%		5	%
Post-65(a)	N/A			N/A			5	%
Prescription drugs	5	%		5	%		5	%
Year that the rate reaches the ultimate trend rate:
Medical:
Pre-65	2020			2020			2018
Post-65(a)	N/A			N/A			2017
Prescription drugs	2018			2018			2018
(a)	Effective 2013, as a result of changes in the post-65 medical plan coverage of the Marathon Petroleum Health Plan and the Marathon Petroleum Retiree Health Plan, increases are the lower of the trend rate or 4 percent.
Assumed health care cost trend rates have a significant effect on the amounts reported for defined benefit retiree health care plans. A one percentage point change in assumed health care cost trend rates would have the following effects:
	1-Percentage-				1-Percentage-
(In millions)	Point Increase				Point Decrease
Effect on total of service and interest cost components	$	5			$	(4	)
Effect on other postretirement benefit obligations	39				(34		)
Plan investment policies and strategies
The investment policies for our pension plan assets reflect the funded status of the plans and expectations regarding our future ability to make further contributions. Long-term investment goals are to: (1) manage the assets in accordance with the legal requirements of all applicable laws; (2) diversify plan investments across asset classes to achieve an optimal balance between risk and return and between income and growth of assets through capital appreciation; and (3) source benefit payments primarily through existing plan assets and anticipated future returns.
The investment goals are implemented to manage the plans' funded status volatility and minimize future cash contributions. The asset allocation strategy will change over time in response to changes primarily in funded status, which is dictated by current and anticipated market conditions, the independent actions of our investment committee, required cash flows to and from the plans and other factors deemed appropriate. Such changes in asset allocation are intended to allocate additional assets to the fixed income asset class should the funded status improve. The fixed income asset class shall be invested in such a manner that its interest rate sensitivity correlates highly with that of the plans' liabilities. Other asset classes are intended to provide additional return with associated higher levels of risk. Investment performance and risk is measured and monitored on an ongoing basis through quarterly investment meetings and periodic asset and liability studies. At December 31, 2013, the plans’ targeted asset allocation was 62 percent equity, private equity, real estate, and timber securities and 38 percent fixed income securities.
Fair value measurements
Plan assets are measured at fair value. The following provides a description of the valuation techniques employed for each major plan asset category at December 31, 2013 and 2012.
Cash and cash equivalents - For 2013, cash and cash equivalents included a collective fund serving as the investment vehicle for the cash reserves and cash held by third-party investment managers. The collective fund was valued at net asset value ("NAV") on a scheduled basis using a cost approach, and was considered a Level 2 asset. Cash and cash equivalents held by third-party investment managers were valued using a cost approach and were considered Level 2. For 2012, cash and cash equivalents included cash on deposit and an investment in a money market mutual fund that invested mainly in short-term instruments and cash, both of which were valued using a market approach and were considered Level 1. The money market mutual fund was valued at the NAV of shares held.
Equity - Equity investments includes common stock, mutual and pooled funds, public and non-public investment trusts and S&P 500 exchange-traded funds. Common stock investments are valued using a market approach, which are priced daily in active markets and are considered Level 1. Mutual and pooled equity funds are well diversified portfolios, representing a mix of strategies in domestic, international and emerging market strategies. Mutual funds are publicly registered, valued at NAV on a daily basis using a market approach and are considered Level 1 assets. Pooled funds are valued at NAV using a market approach and are considered Level 2 assets. Investments in public trusts and S&P 500 exchange-traded funds are valued using a market approach at the closing price reported in an active market and therefore are considered Level 1. Non-public investment trusts are considered Level 2 and are valued using a market approach based on the underlying investments in the trust, which are publicly traded securities.
Fixed Income - Fixed income investments include corporate bonds, U.S. dollar treasury bonds and municipal bonds. These securities are priced on observable inputs using a combination of market, income and cost approaches. These securities are considered Level 2 assets. Fixed income also includes a well diversified bond portfolio structured as a pooled fund. This fund is valued at NAV on a daily basis using a combination of market, income and cost approaches. It is considered a Level 2 asset.
Private Equity - Private equity investments include interests in limited partnerships which are valued using information provided by external managers for each individual investment held in the fund. These holdings are considered Level 3.
Real Estate - Real estate investments consist of interests in limited partnerships. These holdings are either appraised or valued using investment manager’s assessment of assets held. These holdings are considered Level 3.
Other - Other investments include two limited liability companies (“LLCs”) with no public market. The LLCs were formed to acquire timberland in the northwest United States. These holdings are either appraised or valued using investment manager’s assessment of assets held. These holdings are considered Level 3.
The following tables present the fair values of our defined benefit pension plans’ assets, by level within the fair value hierarchy, as of December 31, 2013 and 2012.
	31-Dec-13
(In millions)	Level 1				Level 2				Level 3			Total
Cash and cash equivalents	$	—			$	189			$	—		$	189
Equity:
Common stocks	69				—				—			69
Mutual funds	217				—				—			217
Pooled funds	—				590				—			590
Fixed income:
Corporate	—				356				—			356
Government	—				22				—			22
Pooled funds	—				218				—			218
Private equity	—				—				57			57
Real estate	—				—				60			60
Other	2				—				20			22
Total investments, at fair value	$	288			$	1,375			$	137		$	1,800
	31-Dec-12
(In millions)	Level 1				Level 2				Level 3			Total
Cash and cash equivalents	$	107			$	—			$	—		$	107
Equity:
Exchange-traded funds	166				—				—			166
Investment trusts	17				94				—			111
Pooled funds	—				709				—			709
Fixed income:
Pooled funds	—				258				—			258
Private equity	—				—				56			56
Real estate	—				—				54			54
Other	—				—				17			17
Total investments, at fair value	$	290			$	1,061			$	127		$	1,478
The following is a reconciliation of the beginning and ending balances recorded for plan assets classified as Level 3 in the fair value hierarchy:
	2013
(In millions)	Private				Real				Other			Total
	Equity				Estate
Beginning balance	$	56			$	54			$	17		$	127
Actual return on plan assets:
Realized	13				3				—			16
Unrealized	3				10				3			16
Purchases	7				5				—			12
Sales	(22		)		(12		)		—			(34		)
Ending balance	$	57			$	60			$	20		$	137
	2012
(In millions)	Private				Real				Other			Total
	Equity				Estate
Beginning balance	$	55			$	49			$	17		$	121
Actual return on plan assets:
Realized	5				(2		)		—			3
Unrealized	(3		)		2				—			(1		)
Purchases	12				10				—			22
Sales	(13		)		(5		)		—			(18		)
Ending balance	$	56			$	54			$	17		$	127
Cash Flows
Contributions to defined benefit plans – Our funding policy with respect to the pension plans is to contribute amounts necessary to satisfy minimum pension funding requirements, including requirements of the Pension Protection Act of 2006, plus such additional, discretionary, amounts from time to time as determined appropriate by management. In late 2013, we made pension contributions totaling $161 million. Therefore, we do not anticipate additional contributions will be made in 2014. Cash contributions to be paid from our general assets for the unfunded pension and postretirement plans are estimated to be approximately $18 million and $26 million in 2014.
Estimated future benefit payments – The following gross benefit payments, which reflect expected future service, as appropriate, are expected to be paid in the years indicated.
(In millions)	Pension Benefits				Other Benefits(a)
2014	$	186			$	26
2015	181				29
2016	177				32
2017	178				34
2018	175				38
2019 through 2023	814				231
(a)	Effective 2013, as a result of the Patient Protection and Affordable Care Act, future Medicare reimbursements will no longer be tax deductible and must be used to reduce the costs of providing Medicare part D equivalent prescription drug benefits to retirees.
Contributions to defined contribution plans – We also contribute to several defined contribution plans for eligible employees. Contributions to these plans totaled $76 million, $60 million and $60 million in 2013, 2012 and 2011.
Multiemployer Pension Plan
We contribute to one multiemployer defined benefit pension plan under the terms of a collective-bargaining agreement that covers some of our union-represented employees. The risks of participating in this multiemployer plan are different from single-employer plans in the following aspects:
•	Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers.
•	If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers.
•	If we choose to stop participating in the multiemployer plan, we may be required to pay that plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability.
Our participation in this plan for 2013, 2012 and 2011 is outlined in the table below. The “EIN” column provides the Employee Identification Number for the plan. The most recent Pension Protection Act zone status available in 2013 and 2012 is for the plan’s year ended December 31, 2012 and December 31, 2011, respectively. The zone status is based on information that we received from the plan and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than 65 percent funded. The “FIP/RP Status Pending/Implemented” column indicates a financial improvement plan or a rehabilitation plan has been implemented. The last column lists the expiration date of the collective-bargaining agreement to which the plan is subject. There have been no significant changes that affect the comparability of 2013, 2012 and 2011 contributions. Our portion of the contributions does not make up more than 5 percent of total contributions to the plan.
				Pension Protection				FIP/RP Status		MPC Contributions (In millions)										Surcharge	Expiration Date of
				Act Zone Status				Pending/Implemented												Imposed	Collective - Bargaining
Pension Fund		EIN		2013		2012				2013			2012				2011				Agreement
Central States, Southeast and Southwest Areas Pension Plan(a)		36-6044243		Red		Red		Implemented		$	3		$	4			$	3		No	January 31, 2019
(a)	This agreement has a minimum contribution requirement of $269 per week per employee for 2014. A total of 257 employees participated in the plan as of December 31, 2013.
Multiemployer Health and Welfare Plan
We contribute to one multiemployer health and welfare plan that covers both active employees and retirees. Through the health and welfare plan employees receive medical, dental, vision, prescription and disability coverage. Our contributions to this plan totaled $5 million, $5 million and $4 million for 2013, 2012 and 2011.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Stock-Based Compensation Plans	'
	Stock-Based Compensation Plans
	Description of the Plans
	Effective April 26, 2012, our employees and non-employee directors became eligible to receive equity awards under the Marathon Petroleum Corporation 2012 Incentive Compensation Plan (“MPC 2012 Plan”). The MPC 2012 Plan authorizes the Compensation Committee of our board of directors (“Committee”) to grant non-qualified or incentive stock options, stock appreciation rights, stock awards (including restricted stock and restricted stock unit awards), cash awards and performance awards to our employees, non-employee directors and other plan participants. Under the MPC 2012 Plan, no more than 25 million shares of our common stock may be delivered and no more than 10 million shares of our common stock may be the subject of awards that are not stock options or stock appreciation rights. In the sole discretion of the Committee, 10 million shares of our common stock may be granted as incentive stock options. Shares issued as a result of awards granted under these plans are funded through the issuance of new MPC common shares.
	Prior to the 2011 Spinoff, our employees participated in the Marathon Oil Corporation 2007 Incentive Compensation Plan (“2007 Plan”) and the Marathon Oil Corporation 2003 Incentive Compensation Plan (“2003 Plan”) and received Marathon Oil restricted stock awards and options to purchase shares of Marathon Oil common stock. Effective June 30, 2011, our employees and non-employee directors became eligible to receive equity awards under the Marathon Petroleum Corporation 2011 Second Amended and Restated Incentive Compensation Plan (“MPC 2011 Plan”).
	In connection with the Spinoff, stock compensation awards granted under the 2007 Plan and the 2003 Plan and held by grantees as of June 30, 2011 were adjusted or substituted as follows:
	•	Vested stock options were adjusted and substituted so that the grantee holds options to purchase both MPC and Marathon Oil common stock.
	•	Unvested stock option awards held by MPC employees were replaced with substitute awards of options to purchase shares of MPC common stock.
	•	The adjustment to the Marathon Oil and MPC stock options, when combined, was intended to generally preserve the intrinsic value of each option grant and the ratio of the exercise price to the fair market value of Marathon Oil common stock on June 30, 2011.
	•	Unvested restricted stock awards were replaced with adjusted, substitute awards for restricted shares or units, as applicable, of MPC common stock. The new awards of restricted stock were intended to generally preserve the intrinsic value of the award determined as of June 30, 2011.
	•	Vesting periods of awards were unaffected by the adjustment and substitution.
	Awards granted in connection with the adjustment and substitution of awards originally issued under the 2007 Plan and the 2003 Plan are a part of the MPC 2011 Plan and reduce the maximum number of shares of MPC common stock available for delivery under the MPC 2011 Plan.
	There were 393 MPC employees affected by the adjustment and substitution of awards. The adjustment and substitution of awards did not cause us to recognize incremental compensation expense.
	Stock-based awards under the Plans
	We expense all share-based payments to employees and non-employee directors based on the grant date fair value of the awards over the requisite service period, adjusted for estimated forfeitures.
	Stock Options - We grant stock options to certain officer and non-officer employees and other plan participants. Stock options previously granted under the 2003 Plan and 2007 Plan remain held by employees, subject to the adjustment and substitution of awards described above. All of the stock options granted in 2013 fell under the MPC 2012 Plan. Stock options awarded under the MPC 2011 Plan and the MPC 2012 Plan represent the right to purchase shares of our common stock at its fair market value, which is the closing price of MPC's common stock on the date of grant. Stock options have a maximum term of ten years from the date they are granted, and vest over a requisite service period of three years. We use the Black Scholes option-pricing model to estimate the fair value of stock options granted, which requires the input of subjective assumptions.
	Stock Appreciation Rights (“SARs”) – Prior to 2005, SARs were granted under the 2003 Plan. No SARs have been granted under the 2007 Plan, the MPC 2011 Plan or the MPC 2012 Plan. Similar to stock options, SARs represent the right to receive a payment equal to the excess of the fair market value of shares of MPC or Marathon Oil common stock (in accordance with the adjustment and substitution of awards described above) on the date the right is exercised over the grant price. SARs have a maximum term of ten years from the date they are granted and generally vest over a requisite service period of three years. We use the Black Scholes option-pricing model to estimate the fair value of SARs granted, which requires the input of subjective assumptions.
	Restricted Stock and Restricted Stock Units – We grant restricted stock and restricted stock units to employees, non-employee directors and other plan participants. Restricted stock and restricted stock units previously granted under the 2003 Plan and the 2007 Plan remain held by employees and non-employee directors, subject to the adjustment and substitution of awards described above. In general, restricted stock and restricted stock units granted to employees vest over a requisite service period of three years. Restricted stock and restricted stock unit awards granted after 2011 to officers are subject to an additional one year holding period after the completion of the three-year requisite service period. Prior to vesting, restricted stock recipients who received grants prior to 2012 have the right to vote such stock and receive dividends at the same time regular shareholders are paid. Restricted stock recipients who received grants in 2012 and after have the right to vote such stock; however, dividends are accrued and will be paid upon vesting. Restricted stock units granted to non-employee directors are considered to vest immediately at the time of the grant for accounting purposes, as they are non-forfeitable, but are not issued until the director’s departure from the board of directors. Restricted stock unit recipients do not have the right to vote such shares and receive dividend equivalents. The non-vested shares are not transferable and are held by our transfer agent. The fair values of restricted stock are based on the fair value of our common stock on the grant date.
	Performance Units – We grant performance unit awards to certain officer employees. The target value of all performance units is $1.00, with actual payout up to $2.00 per unit (up to 200% of target). Performance units issued prior to 2012 are paid in cash at the end of the 30-month vesting period at an amount per unit determined based on the total shareholder return ("TSR") of MPC common stock compared to the TSR of selected peer companies’ stock. Performance units issued in 2012 and 2013 under the MPC 2011 and MPC 2012 Plans have a 36-month requisite service period. The payout value of these awards will be determined by the relative ranking of the TSR of MPC common stock compared to the TSR of a select group of peer companies, as well as the Standard & Poor's 500 Energy Index fund over four measurement periods. These awards will be settled 25 percent in MPC common stock and 75 percent in cash. The number of shares actually distributed will be determined by dividing 25 percent of the final payout by the closing price of MPC common stock on the day the Committee certifies the final TSR rankings, or the next trading day if the certification is made outside of normal trading hours. The performance units paying out in cash are accounted for as liability awards and those that settle in shares are accounted for as equity awards. The performance units settling in shares had a grant date fair value of $1.12 per unit for 2013 and $1.09 per unit for 2012, as calculated using a Monte Carlo valuation model.
	Total Stock-Based Compensation Expense
	Total employee stock-based compensation expense was $42 million, $35 million and $28 million in 2013, 2012 and 2011, while the total related income tax benefits were $15 million, $13 million and $11 million, respectively. In 2013, 2012 and in 2011 for the period subsequent to the Spinoff, cash received by MPC upon exercise of stock option awards was $48 million, $108 million and $1 million, respectively. In 2011 for periods prior to the Spinoff, cash received by Marathon Oil upon exercise of stock option awards by MPC employees was $17 million. In 2013, 2012 and in 2011 for the period subsequent to the Spinoff, tax benefits realized by MPC for deductions for stock awards exercised were $18 million, $16 million and less than $1 million, respectively. In 2011 for periods prior to the Spinoff, tax benefits realized by Marathon Oil for deductions for stock awards exercised by MPC employees were $7 million.
	Stock Option Awards
	The Black Scholes option-pricing model values used to value stock option awards granted were determined based on the following weighted average assumptions (information for periods prior to the Spinoff was based on stock option awards for Marathon Oil common stock):
		2013				2012				2011 subsequent to Spinoff				2011 prior to Spinoff
	Weighted average exercise price per share	$	84.65			$	42.02			$	36.18			$	51.93
	Expected annual dividends per share	$	1.4			$	1			$	0.95			$	1
	Expected life in years	6				5.8				5.8				5.3
	Expected volatility	40		%		47		%		48		%		40		%
	Risk-free interest rate	1		%		1.1		%		1.4		%		2		%
	Weighted average grant date fair value of stock option awards granted	$	27.13			$	14.45			$	13.08			$	16.73
	Expected annual dividends per share is estimated using the most recent dividend payment per share as of the grant date. The expected life of stock options granted is based on historical data and represents the period of time that options granted are expected to be held prior to exercise. The assumption for expected volatility of our stock price reflects a weighting of 33 percent of our common stock implied volatility and 67 percent of the historical volatility for a selected group of peer companies. The risk-free interest rate for periods within the expected life of the option is based on the U.S. Treasury yield curve in effect at the time of the grant.
	The following is a summary of our common stock option activity in 2013:
		Number of			Weighted Average Exercise				Weighted Average		Aggregate
		of Shares(a)			Price				Remaining		Intrinsic Value
									Contractual Term		(In millions)
									(in years)
	Outstanding at December 31, 2012	6,172,194			$	36.17
	Granted	408,603			84.65
	Exercised	(1,348,938	)		35.48
	Forfeited, canceled or expired	(84,022	)		43.97
	Outstanding at December 31, 2013	5,147,837			40.08
	Vested and expected to vest at December 31, 2013	5,142,351			40.04				6		$	266
	Exercisable at December 31, 2013	3,674,485			34.63				5.3		210
	(a)	Includes an immaterial number of stock appreciation rights.
	The intrinsic value of options exercised by MPC employees during 2013, 2012 and in 2011 for periods subsequent to the Spinoff was $60 million, $37 million and $1 million, respectively. The intrinsic value of options to purchase Marathon Oil common stock exercised by MPC employees under the 2007 Plan and 2003 Plan during 2011 for periods prior to the Spinoff was $18 million.
	As of December 31, 2013, unrecognized compensation cost related to stock option awards was $7 million, which is expected to be recognized over a weighted average period of 0.7 years.
	Restricted Stock Awards
	The following is a summary of restricted stock award activity of our common stock in 2013:
		Shares of Restricted Stock (“RS”)							Restricted Stock Units (“RSU”)
		Number of			Weighted Average				Number of			Weighted Average
		Shares			Grant Date				Units			Grant Date
					Fair Value							Fair Value
	Outstanding at December 31, 2012	638,073			$	40.83			359,111			$	31.07
	Granted	256,224			87.06				26,399			73.48
	RS's Vested/RSU's Issued	(245,116	)		37.95				(431	)		39.53
	Forfeited	(25,059	)		58.6				—			—
	Outstanding at December 31, 2013	624,122			61.11				385,079			33.96
	Of the 385,079 restricted units outstanding, 383,953 are vested and have a weighted average grant date fair value of $33.89. These vested but unissued units are held by our non-employee directors, are non-forfeitable and are issuable upon the director’s departure from our board of directors.
	The following is a summary of the values related to restricted stock and restricted stock unit awards held by MPC employees and non-employee directors (information for periods prior to the Spinoff is for restricted stock and restricted stock unit awards of Marathon Oil common stock):
		Restricted Stock								Restricted Stock Units
		Intrinsic Value				Weighted Average				Intrinsic Value				Weighted Average
		of Awards				Grant Date Fair				of Awards				Grant Date Fair
		Vesting During				Value of Awards				Issued During				Value of Awards
		the Period				Granted During				the Period				Granted During
(In millions)			the Period			(In millions)				the Period
2013	$	20			$	87.06			$	—			$	73.48
2012	5				43.11				—				44.38
2011- Subsequent to the Spinoff	1				41.54				—				33.78
2011- Prior to the Spinoff	3				48.53				—				45.22
As of December 31, 2013, unrecognized compensation cost related to restricted stock awards was $24 million, which is expected to be recognized over a weighted average period of 1.3 years. There was no material unrecognized compensation cost related to restricted stock unit awards.
Performance Unit Awards
The following table presents a summary of the 2013 activity for performance unit awards to be settled in shares:
	Number
	of Units
Outstanding at December 31, 2012	2,040,000
Granted	1,782,500
Settled	—
Canceled	—
Outstanding at December 31, 2013	3,822,500
The number of shares that would be issued upon target vesting, using the closing price of our common stock on December 31, 2013 would be 41,671 shares.
MPLX Awards
Our wholly-owned subsidiary and the general partner of MPLX, MPLX GP LLC (“MXGP”), maintains a unit-based compensation plan for officers, directors and employees (including any other individual who may be considered an “employee” under a Registration Statement on Form S-8 or any successor form) of MXGP.
The MPLX 2012 Incentive Compensation Plan (“MPLX Plan”) permits various types of equity awards including but not limited to grants of restricted phantom units and performance units. Awards granted under the MPLX Plan will be settled with MPLX units. Compensation expense for these awards was not material to our consolidated financial statements for the years ended December 31, 2013 and 2012.

Leases

Leases	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Leases	'
	Leases
	We lease a wide variety of facilities and equipment under operating leases, including land and building space, office equipment, storage facilities and transportation equipment. Most long-term leases include renewal options and, in certain leases, purchase options. Future minimum commitments as of December 31, 2013, for capital lease obligations and for operating lease obligations having initial or remaining non-cancelable lease terms in excess of one year are as follows:
	(In millions)	Capital			Operating
		Lease			Lease
		Obligations			Obligations
	2014	$	51		$	191
	2015	52			184
	2016	51			152
	2017	50			106
	2018	49			95
	Later years	345			241
	Total minimum lease payments	598			$	969
	Less imputed interest costs	(203		)
	Present value of net minimum lease payments	$	395
	Operating lease rental expense was:
	(In millions)	2013			2012		2011
	Minimum rental	$	213		$	139	$	123
	Contingent rental	—			—		1
	Rental expense	$	213		$	139	$	124

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Text Block [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 December 31, 2013 and 2012, 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 $51 million at both December 31, 2013 and December 31, 2012.
	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 LLC. Both LOOP and LOCAP LLC have secured various financings by assigning certain of their rights under throughput and deficiency agreements that they have entered into with us. 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 follow the terms of the underlying debt obligations, some of which extend through 2037. Our maximum potential undiscounted payments under these agreements for the debt principal totaled $172 million as of December 31, 2013.
	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 $42 million as of December 31, 2013.
	We hold an interest in a 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 December 31, 2013.
	Marathon Oil indemnifications – In conjunction with the Spinoff, we have entered into arrangements with Marathon Oil providing indemnities and guarantees with recorded values of $2 million as of December 31, 2013, which consist of unrecognized tax benefits related to MPC, its consolidated subsidiaries and the RM&T Business operations prior to the Spinoff which are not already reflected in the unrecognized tax benefits described in Note 12, 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 the 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 December 31, 2013, 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 December 31, 2013 and 2012, our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $1.7 billion and $1.4 billion, respectively. The contractual commitments at December 31, 2013 includes $700 million of contingent consideration associated with the acquisition of the Galveston Bay Refinery and Related Assets and $892 million for contributions to North Dakota Pipeline. The contractual commitments at December 31, 2012 included both the base purchase price and the $700 million contingent consideration associated with the acquisition of the Galveston Bay Refinery and Related Assets. See Note 5.

Subsequent_Event

Subsequent Event	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Subsequent Event	'
	Subsequent Event
	On February 3, 2014, we announced that we signed an agreement to purchase a facility in Cincinnati, Ohio from Felda Iffco Sdn Bhd, Malaysia. The plant currently produces several products including biodiesel and glycerin. The capacity of the plant is 4,100 barrels per day. The transaction is expected to close in April 2014.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Selected Quarterly Financial Data	'
	Selected Quarterly Financial Data (Unaudited)
		2013								2012
	(In millions, except per share data)	1st Qtr.		2nd Qtr.		3rd Qtr.		4th Qtr.		1st Qtr.		2nd Qtr.		3rd Qtr.		4th Qtr.
	Revenues	$	23,330	$	25,677	$	26,256	$	24,897	$	20,265	$	20,243	$	21,049	$	20,686
	Income from operations	1,156		960		301		1,008		956		1,307		1,895		1,189
	Net income	730		599		173		631		596		814		1,224		759
	Net income attributable to MPC	725		593		168		626		596		814		1,224		755
	Net income attributable to MPC per share:
	Basic	$	2.19	$	1.84	$	0.54	$	2.09	$	1.71	$	2.39	$	3.61	$	2.26
	Diluted	2.17		1.83		0.54		2.07		1.7		2.38		3.59		2.24
	Dividends paid per share	0.35		0.35		0.42		0.42		0.25		0.25		0.35		0.35

Supplementary_Statistics

Supplementary Statistics	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Supplementary Statistics	'
	Supplementary Statistics (Unaudited)
	(In millions)	2013			2012			2011
	Income from Operations by segment
	Refining & Marketing	$	3,206		$	5,098		$	3,591
	Speedway	375			310			271
	Pipeline Transportation(a)	210			216			199
	Items not allocated to segments:
	Corporate and other unallocated items(a)	(271		)	(336		)	(316		)
	Minnesota Assets sale settlement gain	—			183			—
	Pension settlement expenses	(95		)	(124		)	—
	Income from operations	$	3,425		$	5,347		$	3,745
	Capital Expenditures and Investments(b)(c)
	Refining & Marketing	$	2,094		$	705		$	900
	Speedway(d)	296			340			164
	Pipeline Transportation	234			211			121
	Corporate and Other(e)	165			204			138
	Total	$	2,789		$	1,460		$	1,323
	(a)	Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other segments.
	(b)	Capital expenditures include changes in capital accruals.
	(c)	Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The total consideration amount of $1.15 billion includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 5 to the audited consolidated financial statements.
	(d)	Includes Speedway's acquisitions of convenience stores. See Note 5 to the audited consolidated financial statements.
	(e)	Includes capitalized interest of $28 million, $101 million and $114 million for 2013, 2012 and 2011, respectively.
	Supplementary Statistics (Unaudited)
		2013			2012			2011
	MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)(a)(b)	2,086			1,618			1,599
	Refining & Marketing Operating Statistics(b)
	Refining & Marketing Refined Product Sales Volume (thousands of barrels per day)(c)	2,075			1,599			1,581
	Refining & Marketing Gross Margin (dollars per barrel)(d)	$	13.24		$	17.85		$	14.26
	Crude Oil Capacity Utilization percent(e)	96			100			103
	Refinery Throughputs (thousands of barrels per day):(f)
	Crude oil refined	1,589			1,195			1,177
	Other charge and blendstocks	213			168			181
	Total	1,802			1,363			1,358
	Sour Crude Oil Throughput percent	53			53			52
	WTI-Priced Crude Oil Throughput percent	21			28			27
	Refined Product Yields (thousands of barrels per day):(f)
	Gasoline	921			738			739
	Distillates	572			433			433
	Propane	37			26			25
	Feedstocks and special products	221			109			109
	Heavy fuel oil	31			18			21
	Asphalt	54			62			56
	Total	1,836			1,386			1,383
	Refinery Direct Operating Costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	1.2		$	1		$	0.78
	Depreciation and amortization	1.36			1.44			1.29
	Other manufacturing(h)	4.14			3.15			3.16
	Total	$	6.7		$	5.59		$	5.23
	Refining & Marketing Operating Statistics By Region
	Gulf Coast:(b)
	Refinery Throughputs (thousands of barrels per day):(i)
	Crude oil refined	964
	Other charge and blendstocks	195
	Total	1,159
	Sour Crude Oil Throughput percent	65
	WTI-Priced Crude Oil Throughput percent	7
	Refined Product Yields (thousands of barrels per day):(i)
	Gasoline	551
	Distillates	365
	Propane	23
	Feedstocks and special products	215
	Heavy fuel oil	19
	Asphalt	13
Total	1,186
Refinery Direct Operating Costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	1
Depreciation and amortization	1.09
Other manufacturing(h)	3.98
Total	$	6.07
Supplementary Statistics (Unaudited)
	2013			2012			2011
Refining & Marketing Operating Statistics By Region
Midwest:
Refinery Throughputs (thousands of barrels per day):(i)
Crude oil refined	625
Other charge and blendstocks	54
Total	679
Sour Crude Oil Throughput percent	35
WTI-Priced Crude Oil Throughput percent	42
Refined Product Yields (thousands of barrels per day):(i)
Gasoline	371
Distillates	207
Propane	14
Feedstocks and special products	41
Heavy fuel oil	12
Asphalt	41
Total	686
Refinery Direct Operating Costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	1.47
Depreciation and amortization	1.74
Other manufacturing(h)	4.21
Total	$	7.42
Speedway Operating Statistics
Convenience stores at period-end	1,478			1,464			1,371
Gasoline & distillate sales (millions of gallons)	3,146			3,027			2,938
Gasoline & distillate gross margin (dollars per gallon)(j)	$	0.1441		$	0.1318		$	0.1308
Merchandise sales (in millions)	$	3,135		$	3,058		$	2,924
Merchandise gross margin (in millions)	$	825		$	795		$	719
Same store gasoline sales volume (period over period)	0.5		%	(0.8		)%	(1.7		)%
Same store merchandise sales (period over period)(k)	4.3		%	7		%	6.7		%
Pipeline Transportation Operating Statistics
Pipeline throughput (thousands of barrels per day):(l)
Crude oil pipelines	1,280			1,190			1,184
Refined products pipelines	911			980			1,031
Total	2,191			2,170			2,215
(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. Starting in the fourth quarter of 2013, direct operating costs are no longer included in the Refining & Marketing gross margin and the gross margin is calculated based on total refinery throughput. All prior periods presented have been recalculated to reflect a consistent approach.
(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 36 thousand barrels per day ("mbpd"), 25 mbpd and 28 mbpd for 2013, 2012 and 2011, 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.

Summary_Of_Principal_Accountin1

Summary Of Principal Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Principles Applied In Consolidation	'
	Principles applied in consolidation – These consolidated financial statements include the accounts of our majority-owned, controlled subsidiaries. We consolidate MPLX, in which we own a 73.6 percent controlling financial interest, and we record a noncontrolling interest for the 26.4 percent interest owned by the public.
	Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority shareholders have substantive participating rights in the investee. Income from equity method investments represents our proportionate share of net income generated by the equity method investees.
	Equity method investments are generally carried at our share of net assets plus loans and advances. Such investments are assessed for impairment whenever changes in the facts and circumstances indicate a loss in value has occurred, if the loss is deemed to be other than temporary. When the loss is deemed to be other than temporary, the carrying value of the equity method investment is written down to fair value, and the amount of the write-down is included in net income. Differences in the basis of the investments and the separate net asset values of the investees, if any, are amortized into net income over the remaining useful lives of the underlying assets and liabilities, except for the excess related to goodwill.
Use Of Estimates	'
	Use of estimates – The preparation of financial statements in accordance with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the respective reporting periods.
Revenue Recognition	'
	Revenue recognition – Revenues are recognized when products are shipped or services are provided to customers, title is transferred, the sales price is fixed or determinable and collectability is reasonably assured. Costs associated with revenues are recorded in cost of revenues. Shipping and other transportation costs billed to our customers are presented on a gross basis in revenues and cost of revenues.
	Rebates from vendors are recognized as a reduction of cost of revenues when the initiating transaction occurs. Incentives that are derived from contractual provisions are accrued based on past experience and recognized in cost of revenues. Rebates to customers are reflected as a reduction of revenue and are accrued for in accounts payable on the consolidated balance sheets.
Crude Oil And Refined Product Exchanges And Matching Buy/Sell Transactions	'
	Crude oil and refined product exchanges and matching buy/sell transactions – We enter into exchange contracts and matching buy/sell arrangements whereby we agree to deliver a particular quantity and quality of crude oil or refined products at a specified location and date to a particular counterparty and to receive from the same counterparty the same commodity at a specified location on the same or another specified date. The exchange receipts and deliveries are nonmonetary transactions, with the exception of associated grade or location differentials that are settled in cash. The matching buy/sell purchase and sale transactions are settled in cash. Both exchange and matching buy/sell transactions are accounted for as exchanges of inventory and no revenues are recorded. The exchange transactions are recognized at the carrying amount of the inventory transferred.
Consumer Excise Taxes	'
	Consumer excise taxes – We are required by various governmental authorities, including countries, states and municipalities, to collect and remit taxes on certain consumer products. Such taxes are presented on a gross basis in revenues and costs and expenses in the consolidated statements of income.
Cash And Cash Equivalents	'
	Cash and cash equivalents – Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid debt instruments with maturities of three months or less.
Restricted Cash	'
	Restricted cash - Restricted cash consists of cash advances to be used for the operation and maintenance of an operated pipeline system. At December 31, 2013, the amount of restricted cash included in other current assets on the consolidated balance sheets was $7 million.
Accounts Receivable And Allowance For Doubtful Accounts	'
	Accounts receivable and allowance for doubtful accounts – Our receivables primarily consist of customer accounts receivable. The allowance for doubtful accounts is the best estimate of the amount of probable credit losses in customer accounts receivable and is based on historical write-off experience. We review the allowance quarterly and past-due balances over 180 days are reviewed individually for collectability. All other customer receivables are recorded at the invoiced amounts and generally do not bear interest. Account balances for these customer receivables are generally charged directly to bad debt expense when it becomes probable the receivable will not be collected.
	Approximately 38 percent and 42 percent of our accounts receivable balances at December 31, 2013 and 2012, respectively, are related to sales of crude oil or refinery feedstocks to customers with whom we have master netting agreements. We have master netting agreements with more than 100 companies engaged in the crude oil or refinery feedstock trading and supply business or the petroleum refining industry. A master netting agreement generally provides for a once per month net cash settlement of the accounts receivable from and the accounts payable to a particular counterparty.
Inventories	'
	Inventories – Inventories are carried at the lower of cost or market value. Cost of inventories is determined primarily under the last-in, first-out (“LIFO”) method.
Derivative Instruments	'
	Derivative instruments – We use derivatives to economically hedge a portion of our exposure to commodity price risk and, historically, to interest rate risk. We also have limited authority to use selective derivative instruments that assume market risk. All derivative instruments are recorded at fair value. Commodity derivatives are reflected on the consolidated balance sheets on a net basis by futures commission merchant, as they are governed by master netting agreements. Cash flows related to derivatives used to hedge commodity price risk and interest rate risk are classified in operating activities with the underlying transactions.
	Fair value accounting hedges – We used interest rate swaps to hedge our exposure to interest rate risk associated with fixed interest rate debt in our portfolio. Changes in the fair values of both the hedged item and the related derivative were recognized immediately in net income with an offsetting effect included in the basis of the hedged item. The net effect was to report in net income the extent to which the accounting hedge was not effective in achieving offsetting changes in fair value. We terminated our interest rate swap agreements during 2012. There was a gain on the termination of the agreements, which has been accounted for as an adjustment to our long-term debt balance. The gain is being amortized over the remaining life of the associated debt, which reduces our interest expense.
	Derivatives not designated as accounting hedges –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. Changes in the fair value of derivatives not designated as accounting hedges are recognized immediately in net income.
	Contingent credit features – Our derivative instruments contain no significant contingent credit features.
	Concentrations of credit risk – All of our financial instruments, including derivatives, involve elements of credit and market risk. The most significant portion of our credit risk relates to nonperformance by counterparties. The counterparties to our financial instruments consist primarily of major financial institutions and companies within the energy industry. To manage counterparty risk associated with financial instruments, we select and monitor counterparties based on an assessment of their financial strength and on credit ratings, if available. Additionally, we limit the level of exposure with any single counterparty.
Property, Plant And Equipment	'
	Property, plant and equipment – Property, plant and equipment are recorded at cost and depreciated on a straight-line basis over the estimated useful lives of the assets, which range from four to 42 years. Such assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If the sum of the expected undiscounted future cash flows from the use of the asset and its eventual disposition is less than the carrying amount of the asset, an impairment loss is recognized based on the fair value of the asset.
	When items of property, plant and equipment are sold or otherwise disposed of, any gains or losses are reported in net income. Gains on the disposal of property, plant and equipment are recognized when earned, which is generally at the time of closing. If a loss on disposal is expected, such losses are recognized when the assets are classified as held for sale.
	Interest expense is capitalized for qualifying assets under construction. Capitalized interest costs are included in property, plant and equipment and are depreciated over the useful life of the related asset.
Goodwill	'
	Goodwill – Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in the acquisition of a business. Goodwill is not amortized, but rather is tested for impairment annually and when events or changes in circumstances indicate that the fair value of a reporting unit with goodwill has been reduced below carrying value. The impairment test requires allocating goodwill and other assets and liabilities to reporting units. The fair value of each reporting unit is determined and compared to the book value of the reporting unit. If the fair value of the reporting unit is less than the book value, including goodwill, the implied fair value of goodwill is calculated. The excess, if any, of the book value over the implied fair value of goodwill is charged to net income.
Major Maintenance Activities	'
	Major maintenance activities – Costs for planned turnaround, major maintenance and engineered project activities are expensed in the period incurred. These types of costs include contractor repair services, materials and supplies, equipment rentals and our labor costs.
Environmental Costs	'
	Environmental costs – Environmental expenditures are capitalized if the costs mitigate or prevent future contamination or if the costs improve environmental safety or efficiency of the existing assets. We recognize remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs can be reasonably estimated. The timing of remediation accruals coincides with completion of a feasibility study or the commitment to a formal plan of action. Remediation liabilities are accrued based on estimates of known environmental exposure and are discounted when the estimated amounts are reasonably fixed and determinable. If recoveries of remediation costs from third parties are probable, a receivable is recorded and is discounted when the estimated amount is reasonably fixed and determinable.
Asset Retirement Obligations	'
	Asset retirement obligations – The fair value of asset retirement obligations is recognized in the period in which the obligations are incurred if a reasonable estimate of fair value can be made. Conditional asset retirement obligations for removal and disposal of fire-retardant material from certain refining facilities have been recognized. The fair values recorded for such obligations are based on the most probable current cost projections. The recorded asset retirement obligations are not material to the consolidated financial statements.
	Asset retirement obligations have not been recognized for some assets because the fair value cannot be reasonably estimated since the settlement dates of the obligations are indeterminate. Such obligations will be recognized in the period when sufficient information becomes available to estimate a range of potential settlement dates. The asset retirement obligations principally include the removal of underground storage tanks at our owned and some of our leased convenience stores at or near the time of closure and hazardous material disposal and removal or dismantlement requirements associated with the closure of certain refining, terminal and pipeline assets.
	Our practice is to keep our assets in good operating condition through routine repair and maintenance of component parts in the ordinary course of business and by continuing to make improvements based on technological advances. As a result, we believe that these assets have no expected settlement date for purposes of estimating asset retirement obligations since the dates or ranges of dates upon which we would retire these assets cannot be reasonably estimated at this time.
Income Taxes	'
	Income taxes – Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their tax bases. Deferred tax assets are recorded when it is more likely than not that they will be realized. The realization of deferred tax assets is assessed periodically based on several factors, primarily our expectation to generate sufficient future taxable income.
	For periods prior to the Spinoff, our taxable income was included in the consolidated U.S. federal income tax returns of Marathon Oil and in a number of consolidated state income tax returns. In the accompanying consolidated financial statements, for periods prior to the Spinoff our provision for income taxes was computed as if we were a stand-alone tax-paying entity.
Stock-Based Compensation Arrangements	'
	Stock-based compensation arrangements – The fair value of stock options and stock-settled stock appreciation rights (collectively, “stock option awards”) granted to our employees is estimated on the date of grant using the Black-Scholes option pricing model. The model employs various assumptions, based on management’s estimates at the time of grant, which impact the calculation of fair value and ultimately, the amount of expense that is recognized over the vesting period of the stock option award. Of the required assumptions, the expected life of the stock option award and the expected volatility of our stock price have the most significant impact on the fair value calculation. The average expected life is based on our historical employee exercise behavior. The assumption for expected volatility of our stock price reflects a weighting of 33 percent of our common stock volatility and 67 percent of the historical volatility for a selected group of peer companies.
	The fair value of restricted stock awards granted to our employees is determined based on the fair market value of our common stock on the date of grant. The fair value of performance unit awards granted to our employees is estimated on the date of grant using a Monte Carlo valuation model.
	Our stock-based compensation expense is recognized based on management’s estimate of the awards that are expected to vest, using the straight-line attribution method for all service-based awards with a graded vesting feature. If actual forfeiture results are different than expected, adjustments to recognized compensation expense may be required in future periods. Unearned stock-based compensation is charged to equity when restricted stock awards are granted. Compensation expense is recognized over the vesting period and is adjusted if conditions of the restricted stock award are not met. For periods prior to the Spinoff, we recorded Marathon Oil stock-based compensation expense as non-cash capital contributions.
Renewable fuel identification numbers (RINs)	'
	Renewable fuel identification numbers ("RINs") - We purchase RINs to satisfy a portion of our Renewable Fuel Standard ("RFS2") compliance. We record a short-term intangible asset, included in other current assets on the balance sheet, for RINs owned in excess of our anticipated current period compliance requirements. The asset value is based on the product of the excess RINs as of the balance sheet date, if any, and the average cost of our RINs. We record a current liability, included in other current liabilities on the balance sheet, when we are deficient RINs based on the product of the deficient RINs as of the balance sheet date, if any, and the market price of the RINs at the balance sheet date. The cost of RINs used for compliance is reflected in cost of revenues. Any gains or losses on the sale or expiration of RINs are classified as other income.

Acquisitions_and_Investments_T

Acquisitions and Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Components Of The Fair Value Of Consideration Transferred [Table Text Block]	'
	The components of the fair value of consideration transferred are as follows:
	(In millions)
	Cash	$	1,491
	Fair value of contingent consideration as of acquisition date	600
	Payable to seller	6
	Post-closing adjustment	(9		)
	Total consideration	$	2,088
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	'
	The following table summarizes the final amounts assigned to the assets acquired and liabilities assumed as of the acquisition date.
	(In millions)
	Inventories	$	935
	Other current assets	1
	Property, plant and equipment, net	1,274
	Other noncurrent assets	88
	Accounts payable	(12		)
	Payroll and benefits payable	(14		)
	Long-term debt due within one year(a)	(2		)
	Other current liabilities	(6		)
	Long-term debt(a)	(58		)
	Defined benefit postretirement plan obligations	(43		)
	Deferred credits and other liabilities	(75		)
	Total	$	2,088
	(a)	Represents a capital lease obligation assumed
Business Acquisition, Pro Forma Information [Table Text Block]	'
	The following unaudited pro forma financial information presents consolidated results assuming the Galveston Bay Refinery and Related Assets acquisition occurred on January 1, 2012. 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)	2013			2012
	Sales and other operating revenues (including consumer excise taxes)	$	102,120		$	104,165
	Net income attributable to MPC	2,167			3,625
	Net income attributable to MPC per share - basic	$	6.88		$	10.66
	Net income attributable to MPC per share - diluted	6.84			10.6

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Sales to Related Parties	'
	Sales to related parties were as follows:
	(In millions)	2013			2012		2011
	Equity method investees:
	Centennial	$	—		$	1	$	35
	Other equity method investees	8			7		7
	Marathon Oil Companies	—			—		13
	Total	$	8		$	8	$	55
Purchases From Related Parties	'
	Purchases from related parties were as follows:
	(In millions)	2013			2012		2011
	Equity method investees:
	Centennial	$	3		$	7	$	31
	LOOP	43			44		66
	TAAE	24			—		—
	TACE	130			73		46
	TAME	131			124		153
	Other equity method investees	26			32		30
	Marathon Oil Companies	—			—		1,590
	Total	$	357		$	280	$	1,916
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:
		December 31,
	(In millions)	2013			2012
	Centennial	$	1		$	2
	TAME	1			—
	Total	$	2		$	2
Payables To Related Parties	'
	Payables to related parties, which are included in accounts payable on the consolidated balance sheets, were as follows:
		December 31,
	(In millions)	2013			2012
	LOOP	$	3		$	4
	TAAE	2			—
	TACE	4			2
	TAME	5			5
	Other equity method investees	2			2
	Total	$	16		$	13
Related Party Net Interest and Financial Income	'
	Related party net interest and other financial income for 2013 and 2012 was not material. Related party net interest and other financial income for 2011 was as follows:
	(In millions)	2011
	Dividend income:
	PFD Preferred Stock	$	35
	Interest expense:
	PFD revolving credit agreement	3
	Marathon Oil loan agreement	5
	Interest capitalized	(8		)
	Total	—
	Related party net interest and other financial income	$	35

Income_per_Common_Share_Tables

Income per Common Share (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Summary Of Earnings Per Common Share	'
	(In millions, except per share data)	2013		2012		2011
	Basic earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	2,112	$	3,389	$	2,389
	Income allocated to participating securities	4		6		4
	Income available to common stockholders - basic	$	2,108	$	3,383	$	2,385
	Weighted average common shares outstanding	315		340		356
	Basic earnings per share	$	6.69	$	9.95	$	6.7
	Diluted earnings per share:
	Allocation of earnings:
	Net income attributable to MPC	$	2,112	$	3,389	$	2,389
	Income allocated to participating securities	4		6		4
	Income available to common stockholders - diluted	$	2,108	$	3,383	$	2,385
	Weighted average common shares outstanding	315		340		356
	Effect of dilutive securities	2		2		1
	Weighted average common shares, including dilutive effect	317		342		357
	Diluted earnings per share	$	6.64	$	9.89	$	6.67

Equity_Tables

Equity (Tables)	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Share Repurchases Transacted Through ASR Programs and Open Market Transactions	'
	Total share repurchases transacted through ASR programs and open market transactions were as follows for the respective periods. There were no shares repurchased in 2011.
	(In millions, except per share data)	2013		2012
	Number of shares repurchased(a)	37		28
	Cash paid for shares repurchased	$	2,793	$	1,350
	Effective average cost per delivered share	$	76.14	$	46.73
	(a)	Shares repurchased in 2013 includes 1 million shares received under the November 2012 ASR program, which were paid for in 2012.

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2013
Segment Reporting [Abstract]	'
Income From Operations Attributable To Operating Segments	'
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Year Ended December 31, 2013
	Revenues:
	Customer	$	85,608		$	14,471		$	79		$	100,158
	Intersegment(a)	9,294			4			458			9,756
	Related parties	8			—			—			8
	Segment revenues	94,910			14,475			537			109,922
	Elimination of intersegment revenues	(9,294		)	(4		)	(458		)	(9,756		)
	Total revenues	$	85,616		$	14,471		$	79		$	100,166
	Segment income from operations(b)	$	3,206		$	375		$	210		$	3,791
	Income from equity method investments	28			—			8			36
	Depreciation and amortization(c)	1,011			112			74			1,197
	Capital expenditures and investments(d)(e)(f)	2,094			296			234			2,624
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Year Ended December 31, 2012
	Revenues:
	Customer	$	67,921		$	14,239		$	77		$	82,237
	Intersegment(a)	8,782			4			381			9,167
	Related parties	7			—			1			8
	Segment revenues	76,710			14,243			459			91,412
	Elimination of intersegment revenues	(8,782		)	(4		)	(381		)	(9,167		)
	Total revenues	$	67,928		$	14,239		$	78		$	82,245
	Segment income from operations(b)	$	5,098		$	310		$	216		$	5,624
	Income (loss) from equity method investments	(6		)	—			32			26
	Depreciation and amortization(c)	804			114			54			972
	Capital expenditures and investments(d)(e)	705			340			211			1,256
	(In millions)	Refining & Marketing			Speedway			Pipeline Transportation			Total
	Year Ended December 31, 2011
	Revenues:
	Customer	$	65,028		$	13,490		$	65		$	78,583
	Intersegment(a)	8,301			—			335			8,636
	Related parties	52			—			3			55
	Segment revenues	73,381			13,490			403			87,274
	Elimination of intersegment revenues	(8,301		)	—			(335		)	(8,636		)
	Total revenues	$	65,080		$	13,490		$	68		$	78,638
	Segment income from operations	$	3,591		$	271		$	199		$	4,061
	Income from equity method investments	11			—			39			50
	Depreciation and amortization(c)	718			110			45			873
	Capital expenditures and investments(d)(e)	900			164			121			1,185
	(a)	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.
	(b)	Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other 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)	Includes Speedway’s acquisition of convenience stores. See Note 5.
	(f)	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 5.
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:
	(In millions)	2013			2012			2011
	Segment income from operations	$	3,791		$	5,624		$	4,061
	Items not allocated to segments:
	Corporate and other unallocated items(a)(b)	(271		)	(336		)	(316		)
	Minnesota Assets sale settlement gain(c)	—			183			—
	Pension settlement expenses(d)	(95		)	(124		)	—
	Net interest and other financial income (costs)(e)	(179		)	(109		)	(26		)
	Income before income taxes	$	3,246		$	5,238		$	3,719
	(a)	Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses, including allocations from the Marathon Oil Companies for periods prior to the Spinoff, and costs related to certain non-operating assets.
	(b)	Corporate overhead costs attributable to MPLX were included in the Pipeline Transportation segment subsequent to MPLX’s October 31, 2012 initial public offering.
	(c)	See Note 6.
	(d)	See Note 22.
	(e)	Includes related party net interest and other financial income.
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures	'
	The following reconciles segment capital expenditures and investments to total capital expenditures:
	(In millions)	2013			2012			2011
	Segment capital expenditures and investments	$	2,624		$	1,256		$	1,185
	Less: Investments in equity method investees	124			28			11
	Plus: Items not allocated to segments:
	Capital expenditures not allocated to segments	137			103			24
	Capitalized interest	28			101			114
	Total capital expenditures(a)(b)	$	2,665		$	1,432		$	1,312
	(a)	Capital expenditures include changes in capital accruals.
	(b)	See Note 20 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 total revenues to sales and other operating revenues (including consumer excise taxes) as reported in the consolidated statements of income:
	(In millions)	2013			2012			2011
	Total revenues (as reported above)	$	100,166		$	82,245		$	78,638
	Plus: Corporate and other unallocated items	(6		)	(2		)	—
	Less: Sales to related parties	8			8			55
	Sales and other operating revenues (including consumer excise taxes)	$	100,152		$	82,235		$	78,583
Schedule Of Revenues By Product Line	'
	Revenues by product line were:
	(In millions)	2013			2012			2011
	Refined products	$	93,520		$	76,234		$	73,334
	Merchandise	3,308			3,229			3,090
	Crude oil and refinery feedstocks	2,988			2,514			1,972
	Transportation and other	344			266			242
	Total revenues	100,160			82,243			78,638
	Less: Sales to related parties	8			8			55
	Sales and other operating revenues (including consumer excise taxes)	$	100,152		$	82,235		$	78,583
Total Assets by Reportable Segment	'
	Total assets by reportable segment were:
		December 31,
	(In millions)	2013			2012
	Refining & Marketing	$	19,573		$	17,052
	Speedway	2,064			1,947
	Pipeline Transportation	1,947			1,950
	Corporate and Other	4,801			6,274
	Total consolidated assets	$	28,385		$	27,223

Other_Items_Tables

Other Items (Tables)	12 Months Ended
	Dec. 31, 2013
Other Income and Expenses [Abstract]	'
Net Interest And Other Financial Income (Costs)	'
	Net interest and other financial income (costs) was:
	(In millions)	2013			2012			2011
	Interest:
	Interest income	$	9		$	5		$	3
	Interest expense(a)	(195		)	(191		)	(164		)
	Interest capitalized(a)	28			101			104
	Total net interest	(158		)	(85		)	(57		)
	Other:
	Net foreign currency gains	—			—			12
	Bank service and other fees	(21		)	(25		)	(16		)
	Total other	(21		)	(25		)	(4		)
	Net interest and other financial income (costs)	$	(179	)	$	(110	)	$	(61	)
	(a)	See Note 7 for information on related party interest expense and capitalized interest.

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Components Of Income Tax Provisions (Benefits)	'
	Income tax provisions (benefits) were:
		2013											2012							2011
	(In millions)	Current				Deferred				Total			Current			Deferred		Total		Current		Deferred			Total
	Federal	$	954			$	20			$	974		$	1,185		$	432	$	1,617	$	1,040	$	139		$	1,179
	State and local	131				8				139			169			57		226		152		(16		)	136
	Foreign	5				(5		)		—			(1		)	3		2		15		—			15
	Total	$	1,090			$	23			$	1,113		$	1,353		$	492	$	1,845	$	1,207	$	123		$	1,330
Reconciliation Of Federal Statutory Income Tax Rate	'
	A reconciliation of the federal statutory income tax rate (35 percent) applied to income before income taxes to the provision for income taxes follows:
		2013			2012			2011
	Statutory rate applied to income before income taxes	35	%		35	%		35	%
	State and local income taxes, net of federal income tax effects	3			2			2
	Domestic manufacturing deduction	(2	)		(1	)		(1	)
	Other	(2	)		(1	)		—
	Provision for income taxes	34	%		35	%		36	%
Components Of Deferred Tax Assets And Liabilities	'
	Deferred tax assets and liabilities resulted from the following:
		December 31,
	(In millions)	2013				2012
	Deferred tax assets:
	Employee benefits	$	483			$	585
	Environmental	37				35
	Other	49				55
	Total deferred tax assets	569				675
	Deferred tax liabilities:
	Property, plant and equipment	2,290				2,225
	Inventories	614				610
	Investments in subsidiaries and affiliates	267				307
	Other	70				29
	Total deferred tax liabilities	3,241				3,171
	Net deferred tax liabilities	$	2,672			$	2,496
Components Of Net Deferred Tax Liabilities Classified In Consolidated Balance Sheets	'
	Net deferred tax liabilities were classified in the consolidated balance sheets as follows:
		December 31,
	(In millions)	2013				2012
	Assets:
	Other noncurrent assets	$	2			$	—
	Liabilities:
	Accrued taxes	370				446
	Deferred income taxes	2,304				2,050
	Net deferred tax liabilities	$	2,672			$	2,496
Summary Of Income Tax Returns Subject To Examination	'
	As of December 31, 2013, our income tax returns remain subject to examination in the following major tax jurisdictions for the tax years indicated:
	United States Federal	2010	-	2012
	States	2004	-	2012
Summary Of Activity In Unrecognized Tax Benefits	'
	The following table summarizes the activity in unrecognized tax benefits:
	(In millions)	2013				2012				2011
	January 1 balance	$	40			$	20			$	14
	Additions for tax positions of prior years	30				32				50
	Reductions for tax positions of prior years	(25		)		(6		)		—
	Settlements	(30		)		(6		)		(44		)
	Statute of limitations	(2		)		—				—
	December 31 balance	$	13			$	40			$	20

Inventories_Tables

Inventories (Tables)	12 Months Ended
	Dec. 31, 2013
Inventory Disclosure [Abstract]	'
Summary Of Inventories	'
		December 31,
	(In millions)	2013		2012
	Crude oil and refinery feedstocks	$	1,797	$	1,383
	Refined products	2,367		1,761
	Materials and supplies	425		231
	Merchandise	100		74
	Total (at cost)	$	4,689	$	3,449

Equity_Method_Investments_Tabl

Equity Method Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Schedule Of Equity Method Investments	'
	14	Equity Method Investments
		Ownership as of December 31, 2013		December 31,
	(In millions)			2013				2012
	Centennial	50%		$	29			$	27
	LOCAP LLC	59%		24				26
	LOOP	51%		214				198
	North Dakota Pipeline(a)	38%		24				—
	TAAE	43%		29				—
	TACE	60%		70				29
	TAEI	34%		23				—
	TAME(b)	50%		35				27
	Other			15				14
	Total			$	463			$	321
	(a)	We own a 38 percent interest in the Class B units of this entity. Our Class B units will be converted to an approximate 27 percent ownership interest in the Class A units of this entity upon completion of the Sandpiper pipeline construction project in 2016.
	(b)	Exclu
Summarized Financial Information For Equity Method Investees	'
	Summarized financial information for equity method investees is as follows:
	(In millions)	2013				2012				2011
	Income statement data:
	Revenues and other income	$	1,067			$	1,025			$	1,043
	Income from operations	87				73				128
	Net income	63				47				101
	Balance sheet data - December 31:
	Current assets	$	339			$	217
	Noncurrent assets	1,238				1,163
	Current liabilities	145				161
	Noncurrent liabilities	618				636

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Summary Of Property, Plant And Equipment	'
	(In millions)	Estimated	December 31,
		Useful Lives	2013		2012
	Refining & Marketing	4 - 25 years	$	16,982	$	15,089
	Speedway	4 - 15 years	2,344		2,100
	Pipeline Transportation	16 - 42 years	1,921		1,747
	Corporate and Other	4 - 40 years	546		473
	Total		21,793		19,409
	Less accumulated depreciation		7,872		6,766
	Property, plant and equipment, net		$	13,921	$	12,643

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Changes In Carrying Amount Of Goodwill	'
	The changes in the carrying amount of goodwill for 2013 and 2012 were as follows:
	(In millions)	Refining & Marketing		Speedway		Pipeline		Total
						Transportation
	2012
	Beginning balance	$	551	$	129	$	162	$	842
	Acquisitions(a)	—		88		—		88
	Ending balance	$	551	$	217	$	162	$	930
	2013
	Beginning balance	$	551	$	217	$	162	$	930
	Acquisitions(a)	—		8		—		8
	Ending balance	$	551	$	225	$	162	$	938
	(a)	See Note 5 for information on the acquisitions.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Assets And Liabilities Accounted For At Fair Value On A Recurring Basis	'
	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of December 31, 2013 and 2012 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.
		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	$	—
		December 31, 2012
		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	$	49		$	—		$	—		$	(49	)	$	—	$	45
	Other assets	2			—			—			N/A			2		—
	Total assets at fair value	$	51		$	—		$	—		$	(49	)	$	2	$	45
	Commodity derivative instruments, liabilities	$	88		$	—		$	—		$	(88	)	$	—	$	—
	(a)	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of December 31, 2013 and 2012, cash collateral of $32 million and $39 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 $159 million classified as current.
Reconciliation Of Net Beginning And Ending Balances Recorded For Net Assets And Liabilities Classified As Level 3	'
	The following is a reconciliation of the net beginning and ending balances recorded for net assets/(liabilities) classified as Level 3 in the fair value hierarchy.
	(In millions)	2013			2012			2011
	Beginning balance	$	—		$	—		$	2,402
	Contingent consideration agreement	(600		)	—			—
	Total realized and unrealized losses included in net income	(25		)	(2		)	—
	Purchases of PFD Preferred Stock(a)	—			—			10,326
	Redemptions of PFD Preferred Stock(a)	—			—			(12,730		)
	Settlements of derivative instruments	—			2			2
	Ending balance	$	(625	)	$	—		$	—
	(a)	For information on PFD Preferred Stock, see Note 7. The fair value of our PFD Preferred Stock investment was measured using an income approach since the securities were not publicly traded; therefore, they were classified as Level 3 in the fair value hierarchy.
Assets Measured At Fair Value On A Nonrecurring Basis	'
	The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition.
		Year Ended December 31,
		2013						2012						2011
	(In millions)	Fair Value			Impairment			Fair Value			Impairment			Fair Value		Impairment
	Property, plant and equipment, net	$	1		$	8		$	—		$	—		$	—	$	—
	Other noncurrent assets	—			—			—			14			—		—
Financial Instruments At Fair Value, Excluding Derivative Financial Instruments	'
	The following table summarizes financial instruments on the basis of their nature, characteristics and risk at December 31, 2013 and 2012, excluding the derivative financial instruments and contingent consideration reported above.
		December 31,
		2013						2012
	(In millions)	Fair Value			Carrying			Fair Value			Carrying
					Value						Value
	Financial assets:
	Investments	$	336		$	14		$	263		$	59
	Other	31			30			33			31
	Total financial assets	$	367		$	44		$	296		$	90
	Financial liabilities:
	Long-term debt(a)	$	3,306		$	3,001		$	3,559		$	3,006
	Deferred credits and other liabilities	21			21			23			23
	Total financial liabilities	$	3,327		$	3,022		$	3,582		$	3,029
	(a)	Excludes capital leases

Derivatives_Tables

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Classification Of Gross 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 December 31, 2013 and 2012:
		31-Dec-13
	(In millions)	Asset				Liability				Balance Sheet Location
	Commodity derivatives	$	21			$	53			Other current assets
		31-Dec-12
	(In millions)	Asset				Liability				Balance Sheet Location
	Commodity derivatives	$	49			$	88			Other current assets
Pretax Effect Of Derivative Instruments Designated As Accounting Hedges Of Fair Value	'
	The following table summarizes the pretax effect of derivative instruments designated as accounting hedges of fair value in our consolidated statements of income:
				Gain (Loss)
	(In millions)	Income Statement Location		2013				2012				2011
	Derivative
	Interest rate	Net interest and other financial income (costs)		$	—			$	1			$	19
	Hedged Item
	Long-term debt	Net interest and other financial income (costs)		$	—			$	(1	)		$	(19	)
Open Commodity Derivative Contracts	'
	The table below summarizes open commodity derivative contracts for crude oil and refined products as of December 31, 2013.
		Position		Total Barrels
				(In thousands)
	Crude oil(a)
	Exchange-traded	Long		10,580
	Exchange-traded	Short		-23,900
	Refined Products(a)
	Exchange-traded	Long		3,646
	Exchange-traded	Short		-4,175
	(a)100 percent of these contracts expire in the first quarter of 201
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:
	(In millions)	Gain (Loss)
	Income Statement Location	2013				2012				2011
	Sales and other operating revenues	$	12			$	8			$	(34	)
	Other income	—				—				1
	Cost of revenues	(180		)		65				182
	Total	$	(168	)		$	73			$	149

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Outstanding Borrowings	'
	Our outstanding borrowings at December 31, 2013 and 2012 consisted of the following:
		December 31,
	(In millions)	2013			2012
	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	395			355
	MPLX Operations LLC revolving credit agreement due 2017	—			—
	Trade receivables securitization facility due 2016	—			—
	Total	3,395			3,355
	Unamortized discount	(10		)	(10		)
	Fair value adjustments(a)	11			16
	Amounts due within one year	(23		)	(19		)
	Total long-term debt due after one year	$	3,373		$	3,342
	(a)	See Notes 17 and 18 for information on interest rate swaps.
Schedule Of Debt Payments	'
	The following table shows five years of scheduled debt payments.
	(In millions)
	2014	$	23
	2015	27
	2016	777
	2017	28
	2018	30

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Summary Of Supplemental Cash Flow Information	'
	(In millions)	2013			2012			2011
	Net cash provided by operating activities included:
	Interest paid (net of amounts capitalized)	$	161		$	67		$	5
	Net income taxes paid to taxing authorities(a)	1,099			1,211			617
	Non-cash investing and financing activities:
	Capital lease obligations increase	$	61		$	62		$	26
	Property, plant and equipment contributed by Marathon Oil	—			—			81
	Property, plant and equipment sold	43			—			—
	Preferred equity interest received in contract settlement(b)	—			45			—
	Preferred equity interest dividend received in-kind	—			1			—
	Acquisitions:
	Contingent consideration(c)	600			—			—
	Payable to seller(c)	6			—			—
	Intangible asset acquired	—			3			—
	Liability assumed	—			2			—
	(a)	U.S. and most state income taxes, if incurred, were paid by Marathon Oil for periods prior to the Spinoff. The amount for 2012 includes payments of $181 million for 2011 return period income taxes made to Marathon Oil under our tax sharing agreement, and in return we received an equal amount of tax credits. See Note 25.
	(b)	See Note 6.
	(c)	See Note 5.
Schedule of Reconciliation of Additions to Property Plant and Equipment [Table Text Block]	'
	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:
	(In millions)	2013			2012			2011
	Additions to property, plant and equipment	$	1,206		$	1,369		$	1,185
	Acquisitions(a)	1,386			180			74
	Increase (decrease) in capital accruals	73			(117		)	53
	Total capital expenditures	$	2,665		$	1,432		$	1,312
	(a)	Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The 2012 acquisitions exclude the inventory acquired and liability assumed. See Note 5.
Reconciliation Of Contributions From (Distributions To) Marathon Oil	'
	The following is a reconciliation of distributions to Marathon Oil:
	(In millions)	2011
	Distributions to Marathon Oil per consolidated statements of cash flows	$	(783	)
	Non-cash contributions from Marathon Oil(a)	57
	Distributions to Marathon Oil per consolidated statements of equity / net investment	$	(726	)
	(a)	See Note 7.

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2013
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 (loss) before reclassifications	198			(13		)	—		4			189
	Amounts reclassified from accumulated other comprehensive loss:
	Amortization – prior service credit(a)	(45		)	(4		)	—		—			(49		)
	– actuarial loss(a)	66			3			—		—			69
	– settlement loss(a)	95			—			—		—			95
	Other(b)	—			—			—		(1		)	(1		)
	Tax expense	(43		)	—			—		—			(43		)
	Other comprehensive income (loss)	271			(14		)	—		3			260
	Balance as of December 31, 2013	$	(161	)	$	(50	)	$	4	$	3		$	(204	)
	(a)	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 22.
	(b)	This amount was reclassified out of accumulated other comprehensive loss and is included in selling, general and administrative expenses on the consolidated statements of income.

Defined_Benefit_Pension_and_Ot1

Defined Benefit Pension and Other Postretirement Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Summary Of Defined Benefit Plans With Accumulated Benefit Obligations In Excess Of Plan Assets	'
	The following summarizes our defined benefit pension plans that have accumulated benefit obligations in excess of plan assets.
		December 31,
	(In millions)	2013				2012
	Projected benefit obligations	$	1,927			$	2,192
	Accumulated benefit obligations	1,912				2,035
	Fair value of plan assets	1,800				1,478
Summary Of Projected Benefit Obligations And Funded Status For Defined Benefit Pension And Other Postretirement Plans	'
	The following summarizes the projected benefit obligations and funded status for our defined benefit pension and other postretirement plans:
		Pension Benefits								Other Benefits
	(In millions)	2013				2012				2013			2012
	Change in benefit obligations:
	Benefit obligations at January 1	$	2,192			$	2,685			$	591		$	551
	Service cost	93				66				25			20
	Interest cost	73				94				26			24
	Actuarial (gain) loss	(183		)		117				17			53
	Benefits paid	(248		)		(233		)		(20		)	(17		)
	Liability gain due to curtailment	—				(17		)		—			—
	Other(a)	—				(520		)		48			(40		)
	Benefit obligations at December 31	1,927				2,192				687			591
	Change in plan assets:
	Fair value of plan assets at January 1	1,478				1,423				—			—
	Actual return on plan assets	241				157				—			—
	Employer contributions	329				131				—			—
	Benefits paid from plan assets	(248		)		(233		)		—			—
	Fair value of plan assets at December 31	1,800				1,478				—			—
	Funded status of plans at December 31	$	(127	)		$	(714	)		$	(687	)	$	(591	)
	Amounts recognized in the consolidated balance sheets:
	Current liabilities	$	(18	)		$	(18	)		$	(25	)	$	(21	)
	Noncurrent liabilities	(109		)		(696		)		(662		)	(570		)
	Accrued benefit cost	$	(127	)		$	(714	)		$	(687	)	$	(591	)
	Pretax amounts recognized in accumulated other comprehensive loss:(b)
	Net loss	$	668			$	1,147			$	107		$	93
	Prior service credit	(415		)		(460		)		(30		)	(38		)
	(a)	Includes adjustments related to plan amendments in 2013 and 2012. Also, includes adjustments related to the Galveston Bay Refinery and Related Assets acquisition in 2013.
	(b)	Amounts exclude those related to LOOP, an equity method investee with defined benefit pension and postretirement plans for which net losses of $16 million and $2 million were recorded in accumulated other comprehensive loss in 2013, reflecting our 51 percent share.
Components Of Net Periodic Benefit Cost And Other Comprehensive Loss	'
	Components of net periodic benefit cost and other comprehensive loss – The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive loss for our defined benefit pension and other postretirement plans.
		Pension Benefits											Other Benefits
	(In millions)	2013				2012				2011			2013				2012			2011
	Components of net periodic benefit cost:
	Service cost	$	93			$	66			$	65		$	25			$	20		$	19
	Interest cost	73				94				110			26				24			27
	Expected return on plan assets	(107		)		(104		)		(97		)	—				—			—
	Amortization – prior service cost (credit)	(45		)		(18		)		6			(4		)		(2		)	—
	– actuarial loss	66				93				71			3				2			—
	– net settlement/curtailment loss(a)	95				125				8			—				—			—
	Net periodic benefit cost(b)	$	175			$	256			$	163		$	50			$	44		$	46
	Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):
	Actuarial (gain) loss	$	(317	)		$	46			$	427		$	17			$	53		$	39
	Prior service cost (credit)(c)	—				(520		)		—			4				(40		)	—
	Amortization of actuarial loss	(161		)		(218		)		(79		)	(3		)		(2		)	—
	Amortization of prior service cost (credit)	45				18				(6		)	4				2			—
	Other(d)	—				—				6			—				—			—
	Total recognized in other comprehensive loss	$	(433	)		$	(674	)		$	348		$	22			$	13		$	39
	Total recognized in net periodic benefit cost and other comprehensive loss	$	(258	)		$	(418	)		$	511		$	72			$	57		$	85
	(a)	A curtailment gain was recorded in 2011 on the Speedway pension plan at the end of the transition services period related to the sale of most of our Minnesota Assets in 2010. See Note 6.
	(b)	Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
	(c)	Includes adjustments due to plan amendments approved in 2013 and adjustments due to changes made to the defined pension plans and the post-65 medical plan coverage effective January 1, 2013.
	(d)	Includes adjustments related to the Spinoff in 2011.
Plan Assumptions	'
	Plan assumptions – The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2013, 2012 and 2011.
		Pension Benefits									Other Benefits
		2013			2012			2011			2013		2012			2011
	Weighted-average assumptions used to determine benefit obligation:
	Discount rate	4.3	%		3.45	%		4.3	%		4.95	%	4.05	%		4.65	%
	Rate of compensation increase	3.7	%		5	%		5	%		3.7	%	5	%		5	%
	Weighted-average assumptions used to determine net periodic benefit cost:
	Discount rate	3.88	%		4.06	%		4.98	%		4.11	%	4.54	%		5.55	%
	Expected long-term return on plan assets(a)	7.5	%		7.5	%		8.5	%		—	%	—	%		—	%
	Rate of compensation increase	5	%		5	%		5	%		5	%	5	%		5	%
	(a)	Effective January 1, 2014, the expected long-term rate of return on plan assets changed from 7.50 percent to 7.00 percent due to a change in our plan investment strategy.
Assumed Health Care Cost Trend Rates	'
	The following summarizes the assumed health care cost trend rates.
		December 31,
		2013			2012			2011
	Health care cost trend rate assumed for the following year:
	Medical:
	Pre-65	8	%		8	%		7.5	%
	Post-65(a)	N/A			N/A			7	%
	Prescription drugs	7	%		7	%		7.5	%
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate):
	Medical:
	Pre-65	5	%		5	%		5	%
	Post-65(a)	N/A			N/A			5	%
	Prescription drugs	5	%		5	%		5	%
	Year that the rate reaches the ultimate trend rate:
	Medical:
	Pre-65	2020			2020			2018
	Post-65(a)	N/A			N/A			2017
	Prescription drugs	2018			2018			2018
	(a)	Effective 2013, as a result of changes in the post-65 medical plan coverage of the Marathon Petroleum Health Plan and the Marathon Petroleum Retiree Health Plan, increases are the lower of the trend rate or 4 percent.
Effects Of One Percentage Point Change In Assumed Health Care Cost Trend Rates	'
	A one percentage point change in assumed health care cost trend rates would have the following effects:
		1-Percentage-				1-Percentage-
	(In millions)	Point Increase				Point Decrease
	Effect on total of service and interest cost components	$	5			$	(4	)
	Effect on other postretirement benefit obligations	39				(34		)
Fair Values Of Defined Benefit Pension Plan Assets	'
	The following tables present the fair values of our defined benefit pension plans’ assets, by level within the fair value hierarchy, as of December 31, 2013 and 2012.
		31-Dec-13
	(In millions)	Level 1				Level 2				Level 3			Total
	Cash and cash equivalents	$	—			$	189			$	—		$	189
	Equity:
	Common stocks	69				—				—			69
	Mutual funds	217				—				—			217
	Pooled funds	—				590				—			590
	Fixed income:
	Corporate	—				356				—			356
	Government	—				22				—			22
	Pooled funds	—				218				—			218
	Private equity	—				—				57			57
	Real estate	—				—				60			60
	Other	2				—				20			22
	Total investments, at fair value	$	288			$	1,375			$	137		$	1,800
		31-Dec-12
	(In millions)	Level 1				Level 2				Level 3			Total
	Cash and cash equivalents	$	107			$	—			$	—		$	107
	Equity:
	Exchange-traded funds	166				—				—			166
	Investment trusts	17				94				—			111
	Pooled funds	—				709				—			709
	Fixed income:
	Pooled funds	—				258				—			258
	Private equity	—				—				56			56
	Real estate	—				—				54			54
	Other	—				—				17			17
	Total investments, at fair value	$	290			$	1,061			$	127		$	1,478
Reconciliation Of Beginning And Ending Balances Of Plan Assets Classified As Level 3	'
	The following is a reconciliation of the beginning and ending balances recorded for plan assets classified as Level 3 in the fair value hierarchy:
		2013
	(In millions)	Private				Real				Other			Total
		Equity				Estate
	Beginning balance	$	56			$	54			$	17		$	127
	Actual return on plan assets:
	Realized	13				3				—			16
	Unrealized	3				10				3			16
	Purchases	7				5				—			12
	Sales	(22		)		(12		)		—			(34		)
	Ending balance	$	57			$	60			$	20		$	137
		2012
	(In millions)	Private				Real				Other			Total
		Equity				Estate
	Beginning balance	$	55			$	49			$	17		$	121
	Actual return on plan assets:
	Realized	5				(2		)		—			3
	Unrealized	(3		)		2				—			(1		)
	Purchases	12				10				—			22
	Sales	(13		)		(5		)		—			(18		)
	Ending balance	$	56			$	54			$	17		$	127
Estimated Future Benefit Payment	'
	Estimated future benefit payments – The following gross benefit payments, which reflect expected future service, as appropriate, are expected to be paid in the years indicated.
	(In millions)	Pension Benefits				Other Benefits(a)
	2014	$	186			$	26
	2015	181				29
	2016	177				32
	2017	178				34
	2018	175				38
	2019 through 2023	814				231
	(a)	Effective 2013, as a result of the Patient Protection and Affordable Care Act, future Medicare reimbursements will no longer be tax deductible and must be used to reduce the costs of providing Medicare part D equivalent prescription drug benefits to retirees.
Multi Employer Pension Plan	'
					Pension Protection				FIP/RP Status		MPC Contributions (In millions)										Surcharge	Expiration Date of
					Act Zone Status				Pending/Implemented												Imposed	Collective - Bargaining
	Pension Fund		EIN		2013		2012				2013			2012				2011				Agreement
	Central States, Southeast and Southwest Areas Pension Plan(a)		36-6044243		Red		Red		Implemented		$	3		$	4			$	3		No	January 31, 2019
	(a)	This agreement has a minimum contribution requirement of $269 per week per employee for 2014. A total of 257 employees participated in the plan as of December 31, 2013.

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Weighted Average Assumptions Used To Value Stock Options Awards	'
	The Black Scholes option-pricing model values used to value stock option awards granted were determined based on the following weighted average assumptions (information for periods prior to the Spinoff was based on stock option awards for Marathon Oil common stock):
		2013				2012				2011 subsequent to Spinoff				2011 prior to Spinoff
	Weighted average exercise price per share	$	84.65			$	42.02			$	36.18			$	51.93
	Expected annual dividends per share	$	1.4			$	1			$	0.95			$	1
	Expected life in years	6				5.8				5.8				5.3
	Expected volatility	40		%		47		%		48		%		40		%
	Risk-free interest rate	1		%		1.1		%		1.4		%		2		%
	Weighted average grant date fair value of stock option awards granted	$	27.13			$	14.45			$	13.08			$	16.73
Schedule Of Share-Based Compensation MPC Equity Based Stock Option Activity	'
	The following is a summary of our common stock option activity in 2013:
		Number of			Weighted Average Exercise				Weighted Average		Aggregate
		of Shares(a)			Price				Remaining		Intrinsic Value
									Contractual Term		(In millions)
									(in years)
	Outstanding at December 31, 2012	6,172,194			$	36.17
	Granted	408,603			84.65
	Exercised	(1,348,938	)		35.48
	Forfeited, canceled or expired	(84,022	)		43.97
	Outstanding at December 31, 2013	5,147,837			40.08
	Vested and expected to vest at December 31, 2013	5,142,351			40.04				6		$	266
	Exercisable at December 31, 2013	3,674,485			34.63				5.3		210
	(a)	Includes an immaterial number of stock appreciation rights.
Summary Of Restricted Stock Award Activity	'
	The following is a summary of restricted stock award activity of our common stock in 2013:
		Shares of Restricted Stock (“RS”)							Restricted Stock Units (“RSU”)
		Number of			Weighted Average				Number of			Weighted Average
		Shares			Grant Date				Units			Grant Date
					Fair Value							Fair Value
	Outstanding at December 31, 2012	638,073			$	40.83			359,111			$	31.07
	Granted	256,224			87.06				26,399			73.48
	RS's Vested/RSU's Issued	(245,116	)		37.95				(431	)		39.53
	Forfeited	(25,059	)		58.6				—			—
	Outstanding at December 31, 2013	624,122			61.11				385,079			33.96
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity, Vested And Unvested	'
	The following is a summary of the values related to restricted stock and restricted stock unit awards held by MPC employees and non-employee directors (information for periods prior to the Spinoff is for restricted stock and restricted stock unit awards of Marathon Oil common stock):
		Restricted Stock								Restricted Stock Units
		Intrinsic Value				Weighted Average				Intrinsic Value				Weighted Average
		of Awards				Grant Date Fair				of Awards				Grant Date Fair
		Vesting During				Value of Awards				Issued During				Value of Awards
		the Period				Granted During				the Period				Granted During
		(In millions)				the Period				(In millions)				the Period
	2013	$	20			$	87.06			$	—			$	73.48
	2012	5				43.11				—				44.38
	2011- Subsequent to the Spinoff	1				41.54				—				33.78
	2011- Prior to the Spinoff	3				48.53				—				45.22
Schedule Of Performance Unit Awards	'
	The following table presents a summary of the 2013 activity for performance unit awards to be settled in shares:
		Number
		of Units
	Outstanding at December 31, 2012	2,040,000
	Granted	1,782,500
	Settled	—
	Canceled	—
	Outstanding at December 31, 2013	3,822,500

Leases_Tables

Leases (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Schedule Of Future Minimum Commitments	'
	Future minimum commitments as of December 31, 2013, for capital lease obligations and for operating lease obligations having initial or remaining non-cancelable lease terms in excess of one year are as follows:
	(In millions)	Capital			Operating
		Lease			Lease
		Obligations			Obligations
	2014	$	51		$	191
	2015	52			184
	2016	51			152
	2017	50			106
	2018	49			95
	Later years	345			241
	Total minimum lease payments	598			$	969
	Less imputed interest costs	(203		)
	Present value of net minimum lease payments	$	395
Schedule Of Operating Lease Rental Expense	'
	Operating lease rental expense was:
	(In millions)	2013			2012		2011
	Minimum rental	$	213		$	139	$	123
	Contingent rental	—			—		1
	Rental expense	$	213		$	139	$	124

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Schedule Of Quarterly Financial Information	'
		2013								2012
	(In millions, except per share data)	1st Qtr.		2nd Qtr.		3rd Qtr.		4th Qtr.		1st Qtr.		2nd Qtr.		3rd Qtr.		4th Qtr.
	Revenues	$	23,330	$	25,677	$	26,256	$	24,897	$	20,265	$	20,243	$	21,049	$	20,686
	Income from operations	1,156		960		301		1,008		956		1,307		1,895		1,189
	Net income	730		599		173		631		596		814		1,224		759
	Net income attributable to MPC	725		593		168		626		596		814		1,224		755
	Net income attributable to MPC per share:
	Basic	$	2.19	$	1.84	$	0.54	$	2.09	$	1.71	$	2.39	$	3.61	$	2.26
	Diluted	2.17		1.83		0.54		2.07		1.7		2.38		3.59		2.24
	Dividends paid per share	0.35		0.35		0.42		0.42		0.25		0.25		0.35		0.35

Supplementary_Statistics_Table

Supplementary Statistics (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Supplementary Statistics	'
	(In millions)	2013			2012			2011
	Income from Operations by segment
	Refining & Marketing	$	3,206		$	5,098		$	3,591
	Speedway	375			310			271
	Pipeline Transportation(a)	210			216			199
	Items not allocated to segments:
	Corporate and other unallocated items(a)	(271		)	(336		)	(316		)
	Minnesota Assets sale settlement gain	—			183			—
	Pension settlement expenses	(95		)	(124		)	—
	Income from operations	$	3,425		$	5,347		$	3,745
	Capital Expenditures and Investments(b)(c)
	Refining & Marketing	$	2,094		$	705		$	900
	Speedway(d)	296			340			164
	Pipeline Transportation	234			211			121
	Corporate and Other(e)	165			204			138
	Total	$	2,789		$	1,460		$	1,323
	(a)	Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other segments.
	(b)	Capital expenditures include changes in capital accruals.
	(c)	Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The total consideration amount of $1.15 billion includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 5 to the audited consolidated financial statements.
	(d)	Includes Speedway's acquisitions of convenience stores. See Note 5 to the audited consolidated financial statements.
	(e)	Includes capitalized interest of $28 million, $101 million and $114 million for 2013, 2012 and 2011, respectively.
Operating Statistics	'
		2013			2012			2011
	MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)(a)(b)	2,086			1,618			1,599
	Refining & Marketing Operating Statistics(b)
	Refining & Marketing Refined Product Sales Volume (thousands of barrels per day)(c)	2,075			1,599			1,581
	Refining & Marketing Gross Margin (dollars per barrel)(d)	$	13.24		$	17.85		$	14.26
	Crude Oil Capacity Utilization percent(e)	96			100			103
	Refinery Throughputs (thousands of barrels per day):(f)
	Crude oil refined	1,589			1,195			1,177
	Other charge and blendstocks	213			168			181
	Total	1,802			1,363			1,358
	Sour Crude Oil Throughput percent	53			53			52
	WTI-Priced Crude Oil Throughput percent	21			28			27
	Refined Product Yields (thousands of barrels per day):(f)
	Gasoline	921			738			739
	Distillates	572			433			433
	Propane	37			26			25
	Feedstocks and special products	221			109			109
	Heavy fuel oil	31			18			21
	Asphalt	54			62			56
	Total	1,836			1,386			1,383
	Refinery Direct Operating Costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	1.2		$	1		$	0.78
	Depreciation and amortization	1.36			1.44			1.29
	Other manufacturing(h)	4.14			3.15			3.16
	Total	$	6.7		$	5.59		$	5.23
	Refining & Marketing Operating Statistics By Region
	Gulf Coast:(b)
	Refinery Throughputs (thousands of barrels per day):(i)
	Crude oil refined	964
	Other charge and blendstocks	195
	Total	1,159
	Sour Crude Oil Throughput percent	65
	WTI-Priced Crude Oil Throughput percent	7
	Refined Product Yields (thousands of barrels per day):(i)
	Gasoline	551
	Distillates	365
	Propane	23
	Feedstocks and special products	215
	Heavy fuel oil	19
	Asphalt	13
	Total	1,186
	Refinery Direct Operating Costs (dollars per barrel):(g)
	Planned turnaround and major maintenance	$	1
	Depreciation and amortization	1.09
	Other manufacturing(h)	3.98
	Total	$	6.07
	Supplementary Statistics (Unaudited)
		2013			2012			2011
	Refining & Marketing Operating Statistics By Region
	Midwest:
	Refinery Throughputs (thousands of barrels per day):(i)
	Crude oil refined	625
	Other charge and blendstocks	54
	Total	679
	Sour Crude Oil Throughput percent	35
	WTI-Priced Crude Oil Throughput percent	42
	Refined Product Yields (thousands of barrels per day):(i)
	Gasoline	371
	Distillates	207
	Propane	14
	Feedstocks and special products	41
	Heavy fuel oil	12
	Asphalt	41
Total	686
Refinery Direct Operating Costs (dollars per barrel):(g)
Planned turnaround and major maintenance	$	1.47
Depreciation and amortization	1.74
Other manufacturing(h)	4.21
Total	$	7.42
Speedway Operating Statistics
Convenience stores at period-end	1,478			1,464			1,371
Gasoline & distillate sales (millions of gallons)	3,146			3,027			2,938
Gasoline & distillate gross margin (dollars per gallon)(j)	$	0.1441		$	0.1318		$	0.1308
Merchandise sales (in millions)	$	3,135		$	3,058		$	2,924
Merchandise gross margin (in millions)	$	825		$	795		$	719
Same store gasoline sales volume (period over period)	0.5		%	(0.8		)%	(1.7		)%
Same store merchandise sales (period over period)(k)	4.3		%	7		%	6.7		%
Pipeline Transportation Operating Statistics
Pipeline throughput (thousands of barrels per day):(l)
Crude oil pipelines	1,280			1,190			1,184
Refined products pipelines	911			980			1,031
Total	2,191			2,170			2,215
(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. Starting in the fourth quarter of 2013, direct operating costs are no longer included in the Refining & Marketing gross margin and the gross margin is calculated based on total refinery throughput. All prior periods presented have been recalculated to reflect a consistent approach.
(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 36 thousand barrels per day ("mbpd"), 25 mbpd and 28 mbpd for 2013, 2012 and 2011, 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_Business_Spinof

Description Of Business, Spinoff And Basis Of Presentation (Detail)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Separation and distribution agreement date of Spin off transaction	25-May-11
Distribution of MPC common stock	30-Jun-11

Summary_Of_Principal_Accountin2

Summary Of Principal Accounting Policies (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Summary Of Principal Accounting Policies [Line Items]	'	'
Restricted Cash and Cash Equivalents	7	'
Accounts receivable number of days past-due evaluated for doubtful accounts	'180 days	'
Share-based compensation arrangement by share-based payment award fair value assumptions expected volatility rate - Company stock weighting (in percentage)	33.00%	'
Share-based compensation arrangement by share-based payment award fair value assumptions expected volatility rate - Peer stock weighting (in percentage)	67.00%	'
Minimum [Member]	'	'
Summary Of Principal Accounting Policies [Line Items]	'	'
Number of companies engaged in crude oil or refinery feedstock trading agreement	100	'
Estimated useful lives (in years)	'4 years	'
Maximum [Member]	'	'
Summary Of Principal Accounting Policies [Line Items]	'	'
Estimated useful lives (in years)	'42 years	'
Accounts Receivable With Master Netting Arrangements [Member] | Customer Concentration Risk [Member]	'	'
Summary Of Principal Accounting Policies [Line Items]	'	'
Percentage of accounts receivable related to sales of crude oil refinery feed stocks to customers with master netting agreements	38.00%	42.00%
MPLX LP [Member]	'	'
Summary Of Principal Accounting Policies [Line Items]	'	'
MPC's partnership interest in MPLX (in percentage)	73.60%	'
Percentage of noncontrolling interest (in percentage)	26.40%	'
MPLX LP [Member] | General Partner and Limited Partner [Member]	'	'
Summary Of Principal Accounting Policies [Line Items]	'	'
MPC's partnership interest in MPLX (in percentage)	73.60%	'

MPLX_LP_Narrative_Detail

MPLX LP (Narrative) (Detail) (USD $)

12 Months Ended

0 Months Ended

8 Months Ended

0 Months Ended

12 Months Ended

8 Months Ended

6 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

In Millions, except Share data, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

1-May-13

Dec. 31, 2013

Mar. 01, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Oct. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Apr. 30, 2013

Mar. 01, 2014

Dec. 31, 2013

Oct. 31, 2012

Dec. 31, 2013

Mar. 01, 2014

Mar. 01, 2014

MPLX Pipe Line Holdings LP [Member]

MPLX Pipe Line Holdings LP [Member]

MPLX Pipe Line Holdings LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

MPLX LP [Member]

Cash and Cash Equivalents [Member]

MPLX Revolver [Member]

Subsequent Event [Member]

Commercial Agreements [Member]

Commercial Agreements [Member]

Commercial Agreements [Member]

Operating Agreements [Member]

Operating Agreements [Member]

Management Services Agreements [Member]

Employee Services Agreements [Member]

Pipeline Transportation [Member]

Storage Services [Member]

Storage Services Butane Cavern [Member]

MPLX Pipe Line Holdings LP [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner and Limited Partner [Member]

IPO [Member]

IPO [Member]

MPLX LP [Member]

MPLX LP [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Agreement

Agreement

Commercial Agreements [Member]

Commercial Agreements [Member]

MPLX Pipe Line Holdings LP [Member]

MPLX Pipe Line Holdings LP [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Agreement

Agreement

Subsequent Event [Member]

Noncontrolling Interest [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Initial public offering date of MPLX LP

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'October 2012

'

'

Initial public offering of common units (in number of common units)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

19,895,000

'

'

'

Net proceeds from issuance of MPLX LP common units

$0

$407

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$407

'

'

'

MPC's partnership interest in MPLX (in percentage)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

73.60%

'

'

2.00%

'

'

73.60%

'

'

'

'

Percentage of noncontrolling interest (in percentage)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

26.40%

'

'

'

'

'

'

'

'

'

'

Ownership interest (in percentage)

'

'

'

'

44.00%

'

'

'

'

'

'

'

'

'

'

'

'

56.00%

'

51.00%

'

'

'

'

'

'

MPLX's partnership percent indirect interest in assets

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

Additional interest sold

'

'

'

5.00%

'

13.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds From Sale Of Ownership Interest In Assets By Company In Affiliate

'

'

'

100

'

310

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected ownership interest

'

'

'

'

'

31.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

69.00%

'

'

'

'

'

Cash paid for acquisition

1,515

190

74

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40

270

Number of Agreements

'

'

'

'

'

'

'

'

'

'

'

2

2

9

5

'

'

'

'

'

'

'

'

'

'

'

Duration of Agreements (in years)

'

'

'

'

'

'

'

'3 years

'10 years

'1 year

'5 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Quarters Following Deficiency Payment Over Which Deficiency Credit May Be Applied

'

'

'

'

'

'

4

'

8

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Volume deficiency credits

'

'

'

'

'

'

$34

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Acquisitions_and_Investments_A

Acquisitions and Investments (Acquisition of Refinery and Related Logistics and Marketing Assets) (Detail) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 01, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
				Galveston Bay Refinery And Related Assets [Member]	Galveston Bay Refinery And Related Assets [Member]	Galveston Bay Refinery And Related Assets [Member]	Galveston Bay Refinery And Related Assets [Member]
				site		Prepaid Licensed Refinery Technology Agreements [Member]	Customer Relationships [Member]
				Terminal
				Pipeline
				BPCD
				MW
				BPD
Business Acquisition [Line Items]	'	'	'	'	'	'	'
Refinery capacity (in barrels per calendar day)	'	'	'	451,000	'	'	'
Intrastate natural gas liquid pipelines (in number of pipelines)	'	'	'	3	'	'	'
Number of light product terminals (in number of terminals)	'	'	'	4	'	'	'
Number of branded sites (in number of sites)	'	'	'	1,200	'	'	'
Electric cogeneration capacity, megawatts	'	'	'	1,040	'	'	'
Allocation of space on Colonial Pipeline (in barrels per day)	'	'	'	50,000	'	'	'
Cash paid for acquisition	$1,515,000,000	$190,000,000	$74,000,000	'	$1,491,000,000	'	'
Inventories	'	'	'	'	935,000,000	'	'
Maximum earnout provision payable to the company	'	'	'	'	700,000,000	'	'
Term of payment of maximum earnout provision payable to the company, years	'	'	'	'6 years	'	'	'
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	'	'
Contingent liability	'	'	'	600,000,000	625,000,000	'	'
Contingent liability, current	'	'	'	'	159,000,000	'	'
Post-closing adjustment	'	'	'	'	9,000,000	'	'
Finite-lived intangibles	'	'	'	'	'	68,000,000	20,000,000
Intangible asset, useful life	'	'	'	'	'	'15 years	'4 years
Weighted average useful life	'	'	'	'	'13 years	'	'
Acquisition related costs	'	'	'	'	$7,000,000	'	'

Acquisitions_and_Investments_F

Acquisitions and Investments (Fair Value of Consideration Transferred) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Business Acquisition [Line Items]	'		'	'
Cash	$1,515		$190	$74
Fair value of contingent consideration as of acquisition date	600	[1]	0	0
Payable to seller	6	[1]	0	0
Galveston Bay Refinery And Related Assets [Member]	'		'	'
Business Acquisition [Line Items]	'		'	'
Cash	1,491		'	'
Fair value of contingent consideration as of acquisition date	600		'	'
Payable to seller	6		'	'
Post-closing adjustment	-9		'	'
Total consideration	$2,088		'	'
[1]	See Note 5.

Acquisitions_and_Investments_E

Acquisitions and Investments (Estimated Fair Values of Assets Acquired and Liabilities Assumed) (Details) (Galveston Bay Refinery And Related Assets [Member], USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Galveston Bay Refinery And Related Assets [Member]	'
Business Acquisition [Line Items]	'
Inventories	$935
Other current assets	1
Property, plant and equipment, net	1,274
Other noncurrent assets	88
Accounts payable	-12
Payroll and benefits payable	-14
Long-term debt due within one year	-2	[1]
Other current liabilities	-6
Long-term debt	-58	[1]
Defined benefit postretirement plan obligations	-43
Deferred credits and other liabilities	-75
Total	$2,088
[1]	Represents a capital lease obligation assumed

Acquisitions_and_Investments_S

Acquisitions and Investments (Schedule of Acquisition Related Pro Forma Financial Information) (Details) (Galveston Bay Refinery And Related Assets [Member], USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Galveston Bay Refinery And Related Assets [Member]	'	'
Business Acquisition [Line Items]	'	'
Sales and other operating revenues (including consumer excise taxes)	$102,120	$104,165
Net income attributable to MPC	$2,167	$3,625
Net income attributable to MPC per share - basic (USD per share)	$6.88	$10.66
Net income attributable to MPC per share - diluted (USD per share)	$6.84	$10.60

Acquisitions_and_Investments_A1

Acquisitions and Investments (Acquisitions of Convenience Stores) (Details) (USD $)	1 Months Ended						12 Months Ended
In Millions, unless otherwise specified	Jul. 31, 2012		31-May-12		31-May-11		Dec. 31, 2013		Dec. 31, 2012
	Store		Parcels		Store		Store
			Store
Business Acquisition [Line Items]	'		'		'		'		'
Goodwill, Acquired During Period	'		'		'		$8	[1]	$88	[1]
Speedway [Member]	'		'		'		'		'
Business Acquisition [Line Items]	'		'		'		'		'
Number of convenience stores acquired	10		87		23		9		'
Goodwill, Acquired During Period	$5	[1]	$83	[1]	$9	[1]	$8	[1]	$88	[1]
Number of undeveloped real estate parcels acquired for future development	'		2		'		'		'
[1]	See Note 5 for information on the acquisitions.

Acquisitions_and_Investments_I

Acquisitions and Investments (Investments in Ethanol Companies) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Oct. 02, 2013	Aug. 01, 2013	Aug. 01, 2013	Aug. 01, 2013	Aug. 01, 2013
In Millions, unless otherwise specified	TACE [Member]	Andersons Ethanol Investment Llc [Member]	TAME [Member]	TAME [Member]	TAAE [Member]	TAAE [Member]	Ethanol Interests From Mitsui [Member]	Ethanol Interests From Mitsui [Member]	Ethanol Interests From Mitsui [Member]	Ethanol Interests From Mitsui [Member]
				The Andersons Ethanol Investment Llc [Member]			Companies	TACE [Member]	Andersons Ethanol Investment Llc [Member]	TAAE [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'	'	'
Number Of Businesses In Which Ownership Interests Acquired	'	'	'	'	'	'	3	'	'	'
Cash paid to acquire equity method investments	'	'	'	'	'	'	$75	'	'	'
Percentage acquired	'	'	'	'	'	'	'	24.00%	34.00%	40.00%
Equity method investments, Ownership Percentage	60.00%	34.00%	67.00%	50.00%	43.00%	43.00%	'	'	'	'

Acquisitions_and_Investments_I1

Acquisitions and Investments (Investment in Pipeline) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Jan. 02, 2016	Jan. 02, 2016
	North Dakota Pipeline [Member]	North Dakota Pipeline Class A Units [Member]	North Dakota Pipeline Class A Units [Member]
		Scenario, Forecast [Member]	Scenario, Forecast [Member]
			Maximum [Member]
Schedule of Equity Method Investments [Line Items]	'	'	'
Cash paid to acquire equity method investments	$24	'	'
Equity method investments, Ownership Percentage	37.50%	27.00%	30.00%

Disposition_Detail

Disposition (Detail) (USD $)

12 Months Ended

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 01, 2010

Dec. 01, 2010

Dec. 01, 2010

Dec. 31, 2011

Jul. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 01, 2010

Dec. 01, 2010

Super America [Member]

Wisconsin [Member]

Minnesota Assets Sale Settlement Gain [Member]

Minnesota Assets Sale Settlement Gain [Member]

Minnesota Assets Sale Settlement Gain [Member]

Minnesota Assets Sale Settlement Gain [Member]

Minnesota Assets Sale Settlement Gain [Member]

Minnesota Assets Sale Settlement Gain [Member]

Minnesota Assets Sale Settlement Gain [Member]

Store

Store

BPD

Variable Interest Entity [Member]

Variable Interest Entity [Member]

Variable Interest Entity [Member]

Variable Interest Entity [Member]

Variable Interest Entity [Member]

Maximum [Member]

Dispositions Of Assets [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Refinery capacity (in barrels per calendar day)

'

'

'

'

'

74,000

'

'

'

'

'

'

Number of convenience stores disposed

'

'

'

166

6

'

'

'

'

'

'

'

Approximate transaction value

'

'

'

'

'

$935

'

'

'

'

'

'

Sale of assets, value of inventory

'

'

'

'

'

330

'

'

'

'

'

'

Cash proceeds, total

'

'

'

'

'

740

'

132

'

'

'

'

Preferred equity interest

'

'

'

'

'

'

'

'

'

'

80

'

Maximum provision payable amount, total

'

'

'

'

'

125

'

'

'

'

'

'

Maximum provision payable amount, years

'

'

'

'

'

'8 years

'

'

'

'

'

'

Margin support payable to the buyer, maximum

'

'

'

'

'

'

'

'

'

'

'

60

Margin support payable to the buyer, years

'

'

'

'

'

'2 years

'

'

'

'

'

'

Margin support payable to the buyer, per year

'

'

'

'

'

30

'

'

'

'

'

'

Receivable due from buyer

'

'

'

'

'

'

107

'

'

'

'

'

Guarantees with a maximum exposure

'

'

'

'

'

11

'

'

'

'

'

'

Deferred gain from sale

'

'

'

'

'

89

'

'

'

'

'

'

Buyer redeemed preferred equity interest

16

53

144

'

'

'

'

80

49

'

'

'

Cash proceeds, dividends on preferred equity interest

'

'

'

'

'

'

'

12

4

'

'

'

Cash proceeds, distribution from VIE's offering

'

'

'

'

'

'

'

40

'

'

'

'

Preferred equity interest

0

45

[1]

0

'

'

'

'

45

'

'

'

'

Income before income taxes recognized by the company as a result of the Minnesota Assets' successful IPO

'

'

'

'

'

'

'

'

'

183

'

'

Disposal Group, Amortization of Deferred Gain on Disposal

'

'

'

'

'

'

'

'

$86

'

'

'

Transition services following disposal, term (in number of months)

'13 months

'

'

'

'

'

'

'

'

'

'

'

[1]

See Note 6.

Related_Party_Transactions_Nar

Related Party Transactions (Narrative) (Detail) (USD $)

12 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jun. 30, 2011

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Oct. 02, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2011

Feb. 01, 2011

Dec. 31, 2013

Jul. 18, 2007

Dec. 31, 2005

Jul. 18, 2007

Dec. 31, 2013

Dec. 31, 2011

Oct. 28, 2010

Jul. 18, 2007

Jul. 18, 2007

Jul. 18, 2007

Dec. 31, 2013

Dec. 31, 2013

Centennial [Member]

Centennial [Member]

Centennial [Member]

Centennial [Member]

LOOP [Member]

TAAE [Member]

TAAE [Member]

TACE [Member]

TAME [Member]

Marathon Oil Companies [Member]

Marathon Oil Companies [Member]

Marathon Oil Companies [Member]

Marathon Oil Companies [Member]

PFD [Member]

PFD [Member]

PFD [Member]

PFD [Member]

PFD [Member]

PFD [Member]

PFD [Member]

PFD [Member]

Initial Agreement [Member]

Amended Agreement [Member]

Revenue Bonds [Member]

Revenue Bonds [Member]

Revenue Bonds [Member]

Related Party Credit Agreement [Member]

Related Party Credit Agreement [Member]

Related Party Credit Agreement [Member]

Related Party Credit Agreement [Member]

Euro Dollar Denominated Loans [Member]

Euro Dollar Denominated Loans [Member]

Euro Dollar Denominated Loans [Member]

PFD [Member]

PFD [Member]

Related Party Credit Agreement [Member]

Minimum [Member]

Maximum [Member]

Related Party Credit Agreement [Member]

Related Party Credit Agreement [Member]

Related Party Credit Agreement [Member]

Related Party Credit Agreement [Member]

Related Party Transaction [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity method investments, Ownership Percentage

'

'

'

'

'

50.00%

'

'

51.00%

43.00%

43.00%

60.00%

67.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Separation and distribution agreement date of Spin off transaction

25-May-11

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate cash and cash equivalent balance

'

'

'

$1,625,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum duration of agreement for administrative services with former parent (in years)

'1 year

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Operating pipeline revenue from related parties included in other income

'

'

'

'

'

1,000,000

1,000,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Selling, general and administrative expenses from transactions with related party

'

'

'

'

'

'

'

'

'

'

'

'

'

26,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term receivable from related party

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Impairment of prepaid tariff

'

'

'

'

14,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Initiation Date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

18-Jul-07

28-Oct-10

Line of Credit Facility, Maximum Borrowing Capacity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,900,000,000

'

'

4,400,000,000

'

'

'

'

'

Line of credit facility, expiration date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1-Apr-11

'

'

'

30-Jun-11

'

'

'

'

'

4-May-12

1-Nov-13

Long-term debt payable to related parties - borrowings

0

0

7,748,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,750,000,000

'

'

'

'

'

'

Long-term debt payable to related parties – repayments

0

0

11,366,000,000

'

'

'

'

'

'

'

'

'

'

'

1,050,000,000

'

'

'

'

'

10,320,000,000

'

'

'

'

'

'

Interest rate, description

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

' higher of the prime rate or the sum of 0.5 percent, plus the federal funds rate

'

'

'

'LIBOR plus a margin ranging from 0.25 percent to 1.125 percent

'

'

'

'

Debt instrument basis spread on variable rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.50%

'

'

'

'

0.25%

1.13%

'

'

Debt instrument amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,100,000,000

'

'

'

'

'

'

'

'

'

'

Loan Agreement interest Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.13%

'

'

'

'

'

'

'

'

'

'

Preferred stock redemption price (in USD per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2,000

'

'

'

'

'

'

'

'

'

Property, plant and equipment additions related to capitalized interest incurred by Marathon Oil on behalf of the company

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Significant Noncash Transaction, Value of Consideration Received

$43,000,000

$0

$0

'

'

'

'

'

'

'

'

'

'

$57,000,000

[1]

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

See Note 7.

Related_Party_Transactions_Sal

Related Party Transactions (Sales To Related Parties) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]	'	'	'
Sales to related parties	$8	$8	$55
Marathon Oil Companies [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Sales to related parties	0	0	13
Centennial [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Sales to related parties	0	1	35
Other Equity Method Investees [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Sales to related parties	$8	$7	$7

Related_Party_Transactions_Pur

Related Party Transactions (Purchases From Related Parties) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	$357	$280	$1,916
Marathon Oil Companies [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	0	0	1,590
Centennial [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	3	7	31
LOOP [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	43	44	66
TAAE [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	24	0	0
TACE [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	130	73	46
TAME [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	131	124	153
Other Equity Method Investees [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Related Party Transaction, Purchases from Related Party	$26	$32	$30

Related_Party_Transactions_Rec

Related Party Transactions (Receivables From Related Parties) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	$2	$2
Centennial [Member]	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	1	2
TAME [Member]	'	'
Related Party Transaction [Line Items]	'	'
Current receivables from related parties	$1	$0

Related_Party_Transactions_Pay

Related Party Transactions (Payables To Related Parties) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Related Party Transaction [Line Items]	'	'
Payables to related parties	$16	$13
LOOP [Member]	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	3	4
TAAE [Member]	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	2	0
TACE [Member]	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	4	2
TAME [Member]	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	5	5
Other Equity Method Investees [Member]	'	'
Related Party Transaction [Line Items]	'	'
Payables to related parties	$2	$2

Related_Party_Transactions_Rel

Related Party Transactions (Related Party Net Interest And Other Financial Income) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]	'	'	'
Interest expense	'	'	'
Interest capitalized	'	'	-8
Related party net interest and other financial income	0	1	35
PFD [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Dividend income, PFD Preferred Stock	'	'	35
Interest expense	'	'	3
Marathon Oil Companies [Member]	'	'	'
Related Party Transaction [Line Items]	'	'	'
Interest expense	'	'	$5

Income_per_Common_Share_Narrat

Income per Common Share (Narrative) (Detail)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2011
			Stock Based Compensation Award [Member]	Stock Based Compensation Award [Member]	Stock Based Compensation Award [Member]	Marathon Oil Companies [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'	'
Common stock, shares distributed	362,000,000	361,000,000	'	'	'	356,337,127
Excluded from diluted share calculation	'	'	1,000,000	2,000,000	4,000,000	'

Income_per_Common_Share_Summar

Income per Common Share (Summary Of Earnings Per Common Share) (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic earnings per share:	'	'	'	'	'	'	'	'	'	'	'
Net income attributable to MPC	$626	$168	$593	$725	$755	$1,224	$814	$596	$2,112	$3,389	$2,389
Income allocated to participating securities	'	'	'	'	'	'	'	'	4	6	4
Income available to common stockholders - basic	'	'	'	'	'	'	'	'	2,108	3,383	2,385
Weighted average shares outstanding (in shares)	'	'	'	'	'	'	'	'	315	340	356
Basic earnings per share (in USD per share)	$2.09	$0.54	$1.84	$2.19	$2.26	$3.61	$2.39	$1.71	$6.69	$9.95	$6.70
Diluted earnings per share:	'	'	'	'	'	'	'	'	'	'	'
Net income attributable to MPC	626	168	593	725	755	1,224	814	596	2,112	3,389	2,389
Income allocated to participating securities	'	'	'	'	'	'	'	'	4	6	4
Income available to common stockholders - diluted	'	'	'	'	'	'	'	'	$2,108	$3,383	$2,385
Weighted average shares outstanding (in shares)	'	'	'	'	'	'	'	'	315	340	356
Effect of dilutive securities (in shares)	'	'	'	'	'	'	'	'	2	2	1
Weighted average common shares, including dilutive effect (in shares)	'	'	'	'	'	'	'	'	317	342	357
Diluted earnings per share (in USD per share)	$2.07	$0.54	$1.83	$2.17	$2.24	$3.59	$2.38	$1.70	$6.64	$9.89	$6.67

Equity_Narrative_Detail

Equity (Narrative) (Detail) (USD $)

12 Months Ended

1 Months Ended

12 Months Ended

23 Months Ended

12 Months Ended

12 Months Ended

23 Months Ended

1 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Sep. 26, 2013

Jan. 30, 2013

Feb. 01, 2012

Dec. 31, 2013

Dec. 31, 2013

Feb. 28, 2012

Dec. 31, 2013

Nov. 30, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Jan. 31, 2014

Feb. 01, 2012

Share Repurchase Plan [Member]

Share Repurchase Plan [Member]

Share Repurchase Plan [Member]

Share Repurchase Plan [Member]

Share Repurchase Plan [Member]

Accelerated Share Repurchase Program February 2012 [Member]

Accelerated Share Repurchase Program November 2nd 2012 [Member]

Accelerated Share Repurchase Program November 2nd 2012 [Member]

Accelerated Share Repurchase Program And Open Market Repurchases [Member]

Accelerated Share Repurchase Program And Open Market Repurchases [Member]

Accelerated Share Repurchase Program And Open Market Repurchases [Member]

Accelerated Share Repurchase Program And Open Market Repurchases [Member]

Accelerated Share Repurchase Program And Open Market Repurchases [Member]

Maximum [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

Repurchase Of Common Stock [Member]

Share Repurchase Plan [Member]

Scenario, Forecast [Member]

Common Stock [Member]

Stockholders Equity Note [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock repurchase plan authorized amount

'

'

'

$2,000,000,000

$2,000,000,000

'

'

$6,000,000,000

'

'

'

'

'

'

'

'

$2,000,000,000

Period for repurchase

'

'

'

'

'

'2 years

'

'

'

'

'

'

'

'

'

'

'

Share repurchase authorization ending date

'

'

'

'September 2015

'December 2014

'

'

'

'

'

'

'

'

'

'

'

'

Stock repurchase plan remaining authorized amount

'

'

'

'

'

'

1,860,000,000

'

'

'

'

'

'

'

'

'

'

Repurchase shares of MPC common stock under ASR program

'

'

'

'

'

'

'

'

850,000,000

'

500,000,000

'

'

'

'

'

'

Number of shares repurchased

'

'

'

'

'

'

'

'

'

1

'

37

[1]

28

0

65

'

'

Cash paid for shares repurchased

$2,793,000,000

$1,350,000,000

$0

'

'

'

'

'

'

'

'

$2,793,000,000

$1,350,000,000

'

$4,140,000,000

$12,000,000

'

Effective average cost per delivered share

'

'

'

'

'

'

'

'

'

'

'

$76.14

$46.73

'

$63.61

'

'

[1]

(a)Shares repurchased in 2013 includes 1 million shares received under the November 2012 ASR program, which were paid for in 2012.

Equity_Share_Repurchases_Trans

Equity (Share Repurchases Transacted Through ASR Programs and Open Market Transactions) (Details) (USD $)	12 Months Ended				23 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Stockholders Equity [Line Items]	'		'	'	'
Cash paid for shares repurchased	$2,793		$1,350	0	'
Accelerated Share Repurchase Program November 2nd 2012 [Member]	'		'	'	'
Stockholders Equity [Line Items]	'		'	'	'
Number of shares repurchased	1		'	'	'
Accelerated Share Repurchase Program And Open Market Repurchases [Member]	'		'	'	'
Stockholders Equity [Line Items]	'		'	'	'
Number of shares repurchased	37	[1]	28	0	65
Cash paid for shares repurchased	$2,793		$1,350	'	$4,140
Effective average cost per delivered share	$76.14		$46.73	'	$63.61
[1]	(a)Shares repurchased in 2013 includes 1 million shares received under the November 2012 ASR program, which were paid for in 2012.

Segment_Information_Narrative_

Segment Information (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Segment	BP plc [Member]	None [Member]	None [Member]
			Maximum [Member]	Maximum [Member]
Segment Reporting Information [Line Items]	'	'	'	'
Number of reportable segments	3	'	'	'
Percent of annual revenues	'	10.00%	10.00%	10.00%

Segment_Information_Income_Fro

Segment Information (Income From Operations Attributable To Operating Segments) (Detail) (USD $)

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Customer

'

'

'

'

'

'

'

'

$100,152

$82,235

$78,583

Related parties

'

'

'

'

'

'

'

'

8

8

55

Segment income from operations

1,008

301

960

1,156

1,189

1,895

1,307

956

3,425

5,347

3,745

Income (loss) from equity method investments

'

'

'

'

'

'

'

'

36

26

50

Depreciation and amortization

'

'

'

'

'

'

'

'

1,220

995

891

Capital expenditures and investments

'

'

'

'

'

'

'

'

2,789

[1],[2]

1,460

[1],[2]

1,323

[1],[2]

Acquisitions

'

'

'

'

'

'

'

'

1,386

[3]

180

[3]

74

[3]

Galveston Bay Refinery And Related Assets [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisitions

'

'

'

'

'

'

'

'

1,360

'

'

Operating Segments [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Customer

'

'

'

'

'

'

'

'

100,158

82,237

78,583

Intersegment

'

'

'

'

'

'

'

'

9,756

[4]

9,167

[4]

8,636

[4]

Related parties

'

'

'

'

'

'

'

'

8

8

55

Segment revenues

'

'

'

'

'

'

'

'

109,922

91,412

87,274

Total revenues

'

'

'

'

'

'

'

'

100,166

82,245

78,638

Segment income from operations

'

'

'

'

'

'

'

'

3,791

[5]

5,624

[5]

4,061

[5]

Income (loss) from equity method investments

'

'

'

'

'

'

'

'

36

26

50

Depreciation and amortization

'

'

'

'

'

'

'

'

1,197

[6]

972

[6]

873

[6]

Capital expenditures and investments

'

'

'

'

'

'

'

'

2,624

[2],[7],[8]

1,256

[2],[7]

1,185

[2],[7]

Operating Segments [Member] | Refining & Marketing [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Customer

'

'

'

'

'

'

'

'

85,608

67,921

65,028

Intersegment

'

'

'

'

'

'

'

'

9,294

[4]

8,782

[4]

8,301

[4]

Related parties

'

'

'

'

'

'

'

'

8

7

52

Segment revenues

'

'

'

'

'

'

'

'

94,910

76,710

73,381

Total revenues

'

'

'

'

'

'

'

'

85,616

67,928

65,080

Segment income from operations

'

'

'

'

'

'

'

'

3,206

5,098

3,591

Income (loss) from equity method investments

'

'

'

'

'

'

'

'

28

-6

11

Depreciation and amortization

'

'

'

'

'

'

'

'

1,011

804

718

Capital expenditures and investments

'

'

'

'

'

'

'

'

2,094

[1],[2],[8]

705

[1],[2]

900

[1],[2]

Operating Segments [Member] | Refining & Marketing [Member] | Galveston Bay Refinery And Related Assets [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisitions

'

'

'

'

'

'

'

'

1,290

'

'

Operating Segments [Member] | Speedway [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Customer

'

'

'

'

'

'

'

'

14,471

14,239

13,490

Intersegment

'

'

'

'

'

'

'

'

4

[4]

4

[4]

0

[4]

Related parties

'

'

'

'

'

'

'

'

0

0

0

Segment revenues

'

'

'

'

'

'

'

'

14,475

14,243

13,490

Total revenues

'

'

'

'

'

'

'

'

14,471

14,239

13,490

Segment income from operations

'

'

'

'

'

'

'

'

375

310

271

Income (loss) from equity method investments

'

'

'

'

'

'

'

'

0

0

0

Depreciation and amortization

'

'

'

'

'

'

'

'

112

114

110

Capital expenditures and investments

'

'

'

'

'

'

'

'

296

[2],[7],[8],[9]

340

[2],[7],[9]

164

[2],[7],[9]

Operating Segments [Member] | Pipeline Transportation [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Customer

'

'

'

'

'

'

'

'

79

77

65

Intersegment

'

'

'

'

'

'

'

'

458

[4]

381

[4]

335

[4]

Related parties

'

'

'

'

'

'

'

'

0

1

3

Segment revenues

'

'

'

'

'

'

'

'

537

459

403

Total revenues

'

'

'

'

'

'

'

'

79

78

68

Segment income from operations

'

'

'

'

'

'

'

'

210

[5]

216

[5]

199

[5]

Income (loss) from equity method investments

'

'

'

'

'

'

'

'

8

32

39

Depreciation and amortization

'

'

'

'

'

'

'

'

74

54

45

Capital expenditures and investments

'

'

'

'

'

'

'

'

234

[1],[2],[8]

211

[1],[2]

121

[1],[2]

Operating Segments [Member] | Pipeline Transportation [Member] | Galveston Bay Refinery And Related Assets [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisitions

'

'

'

'

'

'

'

'

70

'

'

Operating Segments [Member] | Pipeline Transportation [Member] | MPLX LP [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Cost of Services, Overhead

'

'

'

'

'

'

'

'

20

4

'

Intersegment Eliminations [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Intersegment

'

'

'

'

'

'

'

'

9,756

9,167

8,636

Intersegment Eliminations [Member] | Refining & Marketing [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Intersegment

'

'

'

'

'

'

'

'

9,294

8,782

8,301

Intersegment Eliminations [Member] | Speedway [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Intersegment

'

'

'

'

'

'

'

'

4

4

'

Intersegment Eliminations [Member] | Pipeline Transportation [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Intersegment

'

'

'

'

'

'

'

'

$458

$381

$335

[1]

Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The total consideration amount of $1.15 billion includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 5 to the audited consolidated financial statements.

[2]

Capital expenditures include changes in capital accruals.

[3]

Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The 2012 acquisitions exclude the inventory acquired and liability assumed. See Note 5.

[4]

Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties.

[5]

Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other 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]

Includes Speedway’s acquisition of convenience stores. See Note 5.

[8]

The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 5.

[9]

Includes Speedway's acquisitions of convenience stores. See Note 5 to the audited consolidated financial statements.

Segment_Information_Reconcilia

Segment Information (Reconciliation Of Segment Income From Operations To Income Before Income Taxes) (Detail) (USD $)

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

$1,008

$301

$960

$1,156

$1,189

$1,895

$1,307

$956

$3,425

$5,347

$3,745

Minnesota Assets sale settlement gain

'

'

'

'

'

'

'

'

6

177

12

Nonoperating income (expense) including related party activity

'

'

'

'

'

'

'

'

-179

[1]

-109

[1]

-26

[1]

Income before income taxes

'

'

'

'

'

'

'

'

3,246

5,238

3,719

Operating Segments [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

3,791

[2]

5,624

[2]

4,061

[2]

Corporate, Non-Segment [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

-271

[2],[3],[4]

-336

[2],[3],[4]

-316

[2],[3],[4]

Segment Reconciling Items [Member]

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Minnesota Assets sale settlement gain

'

'

'

'

'

'

'

'

0

183

[5]

0

Pension settlement expenses

'

'

'

'

'

'

'

'

($95)

[6]

($124)

[6]

$0

[6]

[1]

Includes related party net interest and other financial income.

[2]

Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other segments.

[3]

Corporate overhead costs attributable to MPLX were included in the Pipeline Transportation segment subsequent to MPLX’s October 31, 2012 initial public offering.

[4]

Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses, including allocations from the Marathon Oil Companies for periods prior to the Spinoff, and costs related to certain non-operating assets.

[5]

See Note 6.

[6]

See Note 22.

Segment_Information_Reconcilia1

Segment Information (Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'		'
Capital expenditures and investments	$2,789	[1],[2]	$1,460	[1],[2]	$1,323	[1],[2]
Plus: Items not allocated to segments:	'		'		'
Total capital expenditures	2,665	[2],[3]	1,432	[2],[3]	1,312	[2],[3]
Operating Segments [Member]	'		'		'
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'		'
Capital expenditures and investments	2,624	[2],[4],[5]	1,256	[2],[4]	1,185	[2],[4]
Less: Investments in equity method investees	124		28		11
Corporate, Non-Segment [Member]	'		'		'
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]	'		'		'
Capital expenditures and investments	165	[2],[6]	204	[2],[6]	138	[2],[6]
Plus: Items not allocated to segments:	'		'		'
Capital expenditures excluding capitalized interest	137		103		24
Interest costs capitalized	$28		$101		$114
[1]	Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The total consideration amount of $1.15 billion includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 5 to the audited consolidated financial statements.
[2]	Capital expenditures include changes in capital accruals.
[3]	See Note 20 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
[4]	Includes Speedway’s acquisition of convenience stores. See Note 5.
[5]	The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 5.
[6]	Includes capitalized interest of $28 million, $101 million and $114 million for 2013, 2012 and 2011, respectively.

Segment_Information_Reconcilia2

Segment Information (Reconciliation Of Total Revenues To Sales And Other Operating Revenues) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'
Sales and other operating revenues (including consumer excise taxes)	$100,152	$82,235	$78,583
Less: Sales to related parties	8	8	55
Operating Segments [Member]	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'
Total revenues (as reported above)	100,166	82,245	78,638
Sales and other operating revenues (including consumer excise taxes)	100,158	82,237	78,583
Less: Sales to related parties	8	8	55
Corporate, Non-Segment [Member]	'	'	'
Segment Reporting, Revenue Reconciling Item [Line Items]	'	'	'
Sales and other operating revenues (including consumer excise taxes)	($6)	($2)	$0

Segment_Information_Schedule_O

Segment Information (Schedule Of Revenues By Product Line) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]	'	'	'
Total revenues	$100,160	$82,243	$78,638
Less: Sales to related parties	8	8	55
Sales and other operating revenues (including consumer excise taxes)	100,152	82,235	78,583
Refined Products [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	93,520	76,234	73,334
Merchandise [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	3,308	3,229	3,090
Crude Oil And Refinery Feedstocks [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	2,988	2,514	1,972
Transportation And Other [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	$344	$266	$242

Segment_Information_Total_Asse

Segment Information (Total Assets By Reportable Segment) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total consolidated assets	$28,385	$27,223
Operating Segments [Member] | Refining & Marketing [Member]	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total consolidated assets	19,573	17,052
Operating Segments [Member] | Speedway [Member]	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total consolidated assets	2,064	1,947
Operating Segments [Member] | Pipeline Transportation [Member]	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total consolidated assets	1,947	1,950
Corporate, Non-Segment [Member]	'	'
Segment Reporting, Asset Reconciling Item [Line Items]	'	'
Total consolidated assets	$4,801	$6,274

Other_Items_Net_Interest_And_O

Other Items (Net Interest And Other Financial Income (Costs)) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Interest:	'		'		'
Interest income	$9		$5		$3
Interest expense	-195	[1]	-191	[1]	-164	[1]
Interest capitalized	28	[1]	101	[1]	104	[1]
Total interest	-158		-85		-57
Other:	'		'		'
Net foreign currency gains	0		0		12
Bank service and other fees	-21		-25		-16
Total other	-21		-25		-4
Net interest and other financial income (costs)	($179)		($110)		($61)
[1]	See Note 7 for information on related party interest expense and capitalized interest.

Income_Taxes_Components_Of_Inc

Income Taxes (Components Of Income Tax Provisions (Benefits)) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current	'	'	'
Federal	$954	$1,185	$1,040
State and local	131	169	152
Foreign	5	-1	15
Total	1,090	1,353	1,207
Deferred	'	'	'
Federal	20	432	139
State and local	8	57	-16
Foreign	-5	3	0
Total	23	492	123
Federal	974	1,617	1,179
State and local	139	226	136
Foreign	0	2	15
Total	$1,113	$1,845	$1,330

Income_Taxes_Narrative_Detail

Income Taxes (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Deferred tax assets, valuation allowance	$2	'	'
Unrecognized tax benefits, increase (decrease)	-21	'	'
Tax settlement with Marathon Oil Corporation	39	'	'
Unrecognized tax benefits that would impact effective income tax rate	6	'	'
Uncertain tax positions, reasonably possible increase or decrease during the next twelve months	5	'	'
Unrecognized tax benefits income tax net penalties and interest (receipts) expenses	11	-1	5
Interest and penalties accrued	$15	$9	'

Income_Taxes_Reconciliation_Of

Income Taxes (Reconciliation Of Federal Statutory Income Tax Rate) (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Effective Income Tax Rate Reconciliation, Percent [Abstract]	'	'	'
Statutory rate applied to income before income taxes	35.00%	35.00%	35.00%
State and local income taxes, net of federal income tax effects	3.00%	2.00%	2.00%
Domestic manufacturing deduction	-2.00%	-1.00%	-1.00%
Other	-2.00%	-1.00%	0.00%
Provision for income taxes	34.00%	35.00%	36.00%

Income_Taxes_Components_Of_Def

Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Deferred tax assets:	'	'
Employee benefits	$483	$585
Environmental	37	35
Other	49	55
Total deferred tax assets	569	675
Deferred tax liabilities:	'	'
Property, plant and equipment	2,290	2,225
Inventories	614	610
Investments in subsidiaries and affiliates	267	307
Other	70	29
Total deferred tax liabilities	3,241	3,171
Net deferred tax liabilities	$2,672	$2,496

Income_Taxes_Components_Of_Net

Income Taxes (Components Of Net Deferred Tax Liabilities Classified In Consolidated Balance Sheets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Assets	'	'
Other noncurrent assets	$2	$0
Liabilities	'	'
Accrued taxes	370	446
Deferred income taxes	2,304	2,050
Net deferred tax liabilities	$2,672	$2,496

Income_Taxes_Summary_Of_Income

Income Taxes (Summary Of Income Tax Returns Subject To Examination) (Detail)	12 Months Ended
	Dec. 31, 2012
Minimum [Member] | United States Federal [Member]	'
Income Tax Examination [Line Items]	'
Tax years	'2010
Minimum [Member] | States [Member]	'
Income Tax Examination [Line Items]	'
Tax years	'2004
Maximum [Member] | United States Federal [Member]	'
Income Tax Examination [Line Items]	'
Tax years	'2012
Maximum [Member] | States [Member]	'
Income Tax Examination [Line Items]	'
Tax years	'2012

Income_Taxes_Summary_Of_Activi

Income Taxes (Summary Of Activity In Unrecognized Tax Benefits) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]	'	'	'
January 1 balance	$40	$20	$14
Additions for tax positions of prior years	30	32	50
Reductions for tax positions of prior years	-25	-6	0
Settlements	-30	-6	-44
Statute of limitations	-2	0	0
December 31 balance	$13	$40	$20

Inventories_Summary_Of_Invento

Inventories (Summary Of Inventories) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Crude oil and refinery feedstocks	$1,797	$1,383
Refined products	2,367	1,761
Materials and supplies	425	231
Merchandise	100	74
Total (at cost)	$4,689	$3,449

Inventories_Narrative_Detail

Inventories (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]	'	'	'
Total inventory LIFO percentage	90.00%	93.00%	'
Excess of replacement or current costs over stated LIFO value	$4,084	$4,511	'
Impact on revenues and costs as a result of LIFO liquidations	$0	$0	$4

Equity_Method_Investments_Sche

Equity Method Investments (Schedule Of Equity Method Investments) (Detail) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Oct. 02, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Jan. 02, 2016

In Millions, unless otherwise specified

Centennial [Member]

Centennial [Member]

LOCAP LLC [Member]

LOCAP LLC [Member]

LOOP [Member]

LOOP [Member]

North Dakota Pipeline Class B Units [Member]

North Dakota Pipeline Class B Units [Member]

TAAE [Member]

TAAE [Member]

TAAE [Member]

TACE [Member]

TACE [Member]

TAEI [Member]

TAEI [Member]

TAME [Member]

TAME [Member]

TAME [Member]

Other Equity Method Investees [Member]

Other Equity Method Investees [Member]

North Dakota Pipeline Class A Units [Member]

Direct Ownership Interest [Member]

Scenario, Forecast [Member]

Schedule of Equity Method Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity method investments, Ownership Percentage

'

'

50.00%

'

59.00%

'

51.00%

'

38.00%

[1]

'

43.00%

43.00%

'

60.00%

'

34.00%

'

67.00%

'

50.00%

[2]

'

'

27.00%

Equity method investments

$463

$321

$29

$27

$24

$26

$214

$198

$24

[1]

$0

$29

'

$0

$70

$29

$23

$0

$35

[2]

$27

'

$15

$14

'

[1]

We own a 38 percent interest in the Class B units of this entity. Our Class B units will be converted to an approximate 27 percent ownership interest in the Class A units of this entity upon completion of the Sandpiper pipeline construction project in 2016.

[2]

Excludes TAEI's investment in TAME.

Equity_Method_Investments_Summ

Equity Method Investments (Summarized Financial Information For Equity Method Investees) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income statement data:	'	'	'
Revenues and other income	$1,067	$1,025	$1,043
Income from operations	87	73	128
Net income	63	47	101
Balance sheet data - December 31:	'	'	'
Current assets	339	217	'
Noncurrent assets	1,238	1,163	'
Current liabilities	145	161	'
Noncurrent liabilities	$618	$636	'

Equity_Method_Investments_Narr

Equity Method Investments (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]	'	'	'
Equity method investment difference between carrying amount and underlying equity	$41	'	'
Equity method investment difference between carrying amount and underlying equity, portion related to goodwill which is not being amortized	55	'	'
Equity method investments	463	321	'
Dividends and partnership distributions received from equity method investees	18	37	48
Centennial [Member]	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'
Equity method investments	29	27	'
Percent of debt outstanding	50.00%	'	'
Centennial [Member] | Financial Guarantee [Member] | Master Shelf Agreement [Member]	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'
Guarantees with a maximum exposure	$42	'	'

Property_Plant_And_Equipment_S

Property, Plant And Equipment (Summary Of Property, Plant And Equipment) (Detail) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

In Millions, unless otherwise specified

Minimum [Member]

Maximum [Member]

Corporate, Non-Segment [Member]

Corporate, Non-Segment [Member]

Corporate, Non-Segment [Member]

Corporate, Non-Segment [Member]

Refining & Marketing [Member]

Refining & Marketing [Member]

Refining & Marketing [Member]

Refining & Marketing [Member]

Speedway [Member]

Speedway [Member]

Speedway [Member]

Speedway [Member]

Pipeline Transportation [Member]

Pipeline Transportation [Member]

Pipeline Transportation [Member]

Pipeline Transportation [Member]

Minimum [Member]

Maximum [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Property, Plant and Equipment [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated useful lives (in years)

'

'

'4 years

'42 years

'

'

'4 years

'40 years

'

'

'4 years

'25 years

'

'

'4 years

'15 years

'

'

'16 years

'42 years

Property, plant and equipment, gross

$21,793

$19,409

'

'

$546

$473

'

'

$16,982

$15,089

'

'

$2,344

$2,100

'

'

$1,921

$1,747

'

'

Less accumulated depreciation

7,872

6,766

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net property, plant and equipment

$13,921

$12,643

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Property_Plant_And_Equipment_N

Property, Plant And Equipment (Narrative) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	$21,793	$19,409
Property, plant and equipment, accumulated depreciation	7,872	6,766
Assets Held Under Capital Leases [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	510	417
Property, plant and equipment, accumulated depreciation	111	79
Construction In Progress [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, plant and equipment, gross	$747	$520

Goodwill_Narrative_Detail

Goodwill (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]	'	'
Amount of required impairment	$0	$0

Goodwill_Changes_In_Carrying_A

Goodwill (Changes In Carrying Amount Of Goodwill) (Detail) (USD $)	1 Months Ended						12 Months Ended
In Millions, unless otherwise specified	Jul. 31, 2012		31-May-12		31-May-11		Dec. 31, 2013		Dec. 31, 2012
Goodwill [Line Items]	'		'		'		'		'
Beginning Balance	'		'		'		$930		$842
Acquisitions	'		'		'		8	[1]	88	[1]
Ending Balance	'		'		'		938		930
Refining & Marketing [Member]	'		'		'		'		'
Goodwill [Line Items]	'		'		'		'		'
Beginning Balance	'		'		'		551		551
Acquisitions	'		'		'		0		0
Ending Balance	'		'		'		551		551
Speedway [Member]	'		'		'		'		'
Goodwill [Line Items]	'		'		'		'		'
Beginning Balance	'		'		'		217		129
Acquisitions	5	[1]	83	[1]	9	[1]	8	[1]	88	[1]
Ending Balance	'		'		'		225		217
Pipeline Transportation [Member]	'		'		'		'		'
Goodwill [Line Items]	'		'		'		'		'
Beginning Balance	'		'		'		162		162
Acquisitions	'		'		'		0		0
Ending Balance	'		'		'		$162		$162
[1]	See Note 5 for information on the acquisitions.

Fair_Value_Measurements_Assets

Fair Value Measurements (Assets And Liabilities Accounted For At Fair Value On Recurring Basis) (Detail) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash collateral	$32		$39
Liabilities, current	159		'
Fair Value, Measurements, Recurring [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	0	[1]	0	[1]
Other assets	2	[1]	2	[1]
Total assets at fair value	2	[1]	2	[1]
Commodity derivative instruments, liabilities	0	[1]	0	[1]
Contingent consideration, liability	625	[1],[2]	'
Total liabilities at fair value	625	[1]	'
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	21		49
Other assets	2		2
Total assets at fair value	23		51
Commodity derivative instruments, liabilities	53		88
Contingent consideration, liability	0		'
Total liabilities at fair value	53		'
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
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		'
Total liabilities at fair value	0		'
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
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	625	[2]	'
Total liabilities at fair value	625		'
Collateral [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	-21	[3]	-49	[3]
Total assets at fair value	-21	[3]	-49	[3]
Commodity derivative instruments, liabilities	-53	[3]	-88	[3]
Total liabilities at fair value	-53	[3]	'
Collateral Pledged Not Offset [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Commodity derivative instruments, assets	61		45
Other assets	0		0
Total assets at fair value	61		45
Commodity derivative instruments, liabilities	0		0
Contingent consideration, liability	0		'
Total liabilities at fair value	$0		'
[1]	We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.
[2]	Includes $159 million classified as current.
[3]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of December 31, 2013 and 2012, cash collateral of $32 million and $39 million, respectively, was netted with mark-to-market derivative liabilities.

Fair_Value_Measurements_Narrat

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

3 Months Ended

12 Months Ended

12 Months Ended

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Centennial [Member]

Fair Value, Measurements, Nonrecurring [Member]

Fair Value, Measurements, Nonrecurring [Member]

Fair Value, Measurements, Nonrecurring [Member]

Fair Value, Measurements, Nonrecurring [Member]

Derivative [Member]

Derivative [Member]

Derivative [Member]

Contingent Consideration [Member]

Galveston Bay Refinery And Related Assets [Member]

Galveston Bay Refinery And Related Assets [Member]

Galveston Bay Refinery And Related Assets [Member]

Centennial [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Minimum [Member]

Maximum [Member]

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

'

'

Maximum earnout provision payable to the company

'

'

'

'

'

'

'

'

'

700,000,000

'

'

Fair Value Measurement With Unobservable Inputs Internal And External Crack Spread Forecasts1

'

'

'

'

'

'

'

'

'

'

13

18

Discount rate

'

'

'

'

'

'

'

'

'

'

5.00%

10.00%

Unrealized losses included in net income

'

'

'

'

'

0

0

1,000,000

25,000,000

'

'

'

Impairment charge

'

8,000,000

0

0

'

'

'

'

'

'

'

'

Impairment of prepaid tariff

$14,000,000

$0

$14,000,000

$0

$14,000,000

'

'

'

'

'

'

'

Fair_Value_Measurements_Reconc

Fair Value Measurements (Reconciliation Of Net Beginning And Ending Balances Recorded For Net Assets And Liabilities Classified As Level 3) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]	'		'		'
Beginning balance	$0		$0		$2,402
Contingent consideration agreement	-600		0		0
Total realized and unrealized losses included in net income	-25		-2		0
Purchases of PFD Preferred Stock	0	[1]	0	[1]	10,326	[1]
Redemptions of PFD Preferred Stock	0	[1]	0	[1]	-12,730	[1]
Settlements of derivative instruments	0		2		2
Ending balance	($625)		$0		$0
[1]	For information on PFD Preferred Stock, see Note 7. The fair value of our PFD Preferred Stock investment was measured using an income approach since the securities were not publicly traded; therefore, they were classified as Level 3 in the fair value hierarchy.

Fair_Value_Measurements_Assets1

Fair Value Measurements (Assets Measured At Fair Value On Nonrecurring Basis) (Detail) (Fair Value, Measurements, Nonrecurring [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Measurements, Nonrecurring [Member]	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'
Property, plant and equipment, net, Fair Value	$1	$0	$0
Property, plant and equipment, net, Impairment	8	0	0
Other noncurrent assets, Fair Value	0	0	0
Other noncurrent assets, Impairment	$0	$14	$0

Fair_Value_Measurements_Financ

Fair Value Measurements (Financial Instruments At Fair Value, Excluding Derivative Financial Instruments) (Detail) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value [Member]	'		'
Financial assets:	'		'
Investments	$336		$263
Other	31		33
Total financial assets	367		296
Financial liabilities:	'		'
Long-term debt	3,306	[1]	3,559	[1]
Deferred credits and other liabilities	21		23
Total financial liabilities	3,327		3,582
Carrying Value [Member]	'		'
Financial assets:	'		'
Investments	14		59
Other	30		31
Total financial assets	44		90
Financial liabilities:	'		'
Long-term debt	3,001	[1]	3,006	[1]
Deferred credits and other liabilities	21		23
Total financial liabilities	$3,022		$3,029
[1]	Excludes capital leases

Derivatives_Classification_Of_

Derivatives (Classification Of Gross Fair Values Of Derivative Instruments, Excluding Cash Collateral) (Detail) (Commodity Derivatives [Member], Other Current Assets [Member], USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Commodity Derivatives [Member] | Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Asset	$21	$49
Liability	$53	$88

Derivatives_Narrative_Detail

Derivatives (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Notes Payable And Other Payables [Member] | 3.50% Senior Notes Due In March 2016 [Member]	'	'	'
Derivative [Line Items]	'	'	'
Debt instrument, interest rate (in percentage)	'	3.50%	'
Maturity period of senior notes	'	'March 2016	'
Interest Rate Swap [Member]	'	'	'
Derivative [Line Items]	'	'	'
Notional amount of interest rate swap agreements	'	'	$500
Hedge agreements	' 3.50 percent senior notes due in March 2016	'	'
Gain on the termination of the transactions	'	20	'
Hedge ineffectiveness of interest rate swaps	'	$0	'

Derivatives_Pretax_Effect_Of_D

Derivatives (Pretax Effect Of Derivative Instruments Designated As Accounting Hedges Of Fair Value) (Detail) (Net Interest And Other Financial Income Costs [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative [Member] | Interest Rate Derivatives [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (loss)	$0	$1	$19
Hedged Item [Member] | Long-term Debt [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (loss)	$0	($1)	($19)

Derivatives_Open_Commodity_Der

Derivatives (Open Commodity Derivative Contracts) (Detail)	12 Months Ended
	Dec. 31, 2013
Crude Oil Exchange-Traded [Member]	'
Derivative [Line Items]	'
Percentage of derivative contracts expiring in the period	100.00%
Derivative contract expiration date	31-Mar-14
Crude Oil Exchange-Traded [Member] | Long [Member]	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	10,580,000	[1]
Crude Oil Exchange-Traded [Member] | Short [Member]	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	-23,900,000	[1]
Refined Products Exchange-Traded [Member]	'
Derivative [Line Items]	'
Percentage of derivative contracts expiring in the period	100.00%
Derivative contract expiration date	31-Mar-14
Refined Products Exchange-Traded [Member] | Long [Member]	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	3,646,000	[1]
Refined Products Exchange-Traded [Member] | Short [Member]	'
Derivative [Line Items]	'
Notional Contracts (in thousands of Total Barrels)	-4,175,000	[1]
[1]	of these contracts expire in the first quarter of 2014.

Derivatives_Effect_Of_Commodit

Derivatives (Effect Of Commodity Derivative Instruments In Statements Of Income) (Detail) (Commodity Derivatives [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (Loss)	($168)	$73	$149
Sales And Other Operating Revenues [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (Loss)	12	8	-34
Other Income [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (Loss)	0	0	1
Cost Of Revenues [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (Loss)	($180)	$65	$182

Debt_Outstanding_Borrowings_De

Debt (Outstanding Borrowings) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]	'		'
Total	$3,395		$3,355
Unamortized discount	-10		-10
Fair value adjustments	11	[1]	16	[1]
Long-term debt due within one year	-23		-19
Total long-term debt due after one year	3,373		3,342
MPC Revolver [Member]	'		'
Debt Instrument [Line Items]	'		'
Borrowings outstanding at period end	0		0
Consolidated Subsidiaries [Member] | Trade Receivables Securitization [Member]	'		'
Debt Instrument [Line Items]	'		'
Trade receivables securitization facility due 2016	0		0
MPLX Operations LLC [Member] | MPLX Revolver [Member]	'		'
Debt Instrument [Line Items]	'		'
Borrowings outstanding at period end	0		0
Senior Notes [Member] | 3.500% Senior Notes Due March 1, 2016 [Member]	'		'
Debt Instrument [Line Items]	'		'
Senior notes	750		750
Debt instrument, interest rate	3.50%		'
Debt instrument, maturity date	1-Mar-16		'
Senior Notes [Member] | 5.125% Senior Notes Due March 1, 2021 [Member]	'		'
Debt Instrument [Line Items]	'		'
Senior notes	1,000		1,000
Debt instrument, interest rate	5.13%		'
Debt instrument, maturity date	1-Mar-21		'
Senior Notes [Member] | 6.500% Senior Notes Due March 1, 2041 [Member]	'		'
Debt Instrument [Line Items]	'		'
Senior notes	1,250		1,250
Debt instrument, interest rate	6.50%		'
Debt instrument, maturity date	1-Mar-41		'
Capital Lease Obligations [Member] | Consolidated Subsidiaries [Member]	'		'
Debt Instrument [Line Items]	'		'
Capital lease obligations due 2014-2028	$395		$355
Trade Receivables Securitization [Member] | Consolidated Subsidiaries [Member]	'		'
Debt Instrument [Line Items]	'		'
Line of credit facility, expiration date	31-Dec-14		'
Revolving Credit Facility [Member]	'		'
Debt Instrument [Line Items]	'		'
Line of credit facility, expiration date	14-Sep-17		'
Revolving Credit Facility [Member] | MPLX Operations LLC [Member]	'		'
Debt Instrument [Line Items]	'		'
Line of credit facility, expiration date	31-Oct-17		'
[1]	See Notes 17 and 18 for information on interest rate swaps.

Debt_Schedule_Of_Debt_Payments

Debt (Schedule Of Debt Payments) (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Maturities of Long-term Debt [Abstract]	'
2014	$23
2015	27
2016	777
2017	28
2018	$30

Debt_Narrative_Detail

Debt (Narrative) (Detail) (USD $)

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 18, 2013

Dec. 18, 2013

Dec. 18, 2013

Dec. 31, 2013

Dec. 31, 2012

Trade Receivables Securitization [Member]

MPC Revolver [Member]

MPC Revolver [Member]

MPC Revolver [Member]

MPC Revolver [Member]

MPC Revolver [Member]

MPLX Revolver [Member]

MPLX Revolver [Member]

MPLX Revolver [Member]

MPLX Revolver [Member]

MPLX Revolver [Member]

Trade Receivables Securitization [Member]

Trade Receivables Securitization [Member]

Trade Receivables Securitization [Member]

Trade Receivables Securitization [Member]

Trade Receivables Securitization [Member]

Trade Receivables Securitization [Member]

Revolving Credit Facility [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Minimum [Member]

MPLX Operations LLC [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Minimum [Member]

Letter of Credit [Member]

Secured Debt [Member]

Consolidated Subsidiaries [Member]

Consolidated Subsidiaries [Member]

Period

Bridge Loan [Member]

Revolving Credit Facility [Member]

Letter of Credit [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

MPLX Operations LLC [Member]

MPLX Operations LLC [Member]

MPLX Operations LLC [Member]

MPLX Operations LLC [Member]

Period

Bridge Loan [Member]

Revolving Credit Facility [Member]

Letter of Credit [Member]

Revolving Credit Facility [Member]

Period

Line of Credit Facility [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Trade receivables securitization facility due 2016

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0

$0

Line of Credit Facility, Current Borrowing Capacity

'

'

100,000,000

2,500,000,000

2,000,000,000

'

'

50,000,000

500,000,000

250,000,000

'

'

'

'

'

'

'

Line of Credit Facility, Maximum Borrowing Capacity

'

'

'

'

'

'

'

'

'

'

'

'

1,300,000,000

1,250,000,000

1,300,000,000

'

'

Line Of Credit Facility Additional Borrowing Capacity

'

'

'

$500,000,000

'

'

'

'

$300,000,000

'

'

'

'

'

'

'

'

Number Of Renewal Periods

'

2

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

Line Of Credit Facility Duration Of Renewal Period

'

'1 year

'

'

'

'

'1 year

'

'

'

'

'

'

'

'

'

'

Lender Holding Percentage Of Outstanding Commitments Needed To Approve Increase In Borrowing Capacity

'

'

'

'

'

50.00%

'

'

'

'

50.00%

'

'

'

'

'

'

Ratio of Indebtedness to Net Capital

'

'

'

0.65

'

'

'

'

'

'

'

'

'

'

'

'

'

Number Of Prior Quarterly Reporting Periods Covenant

'

'

'

'

'

'

'

'

4

'

'

'

'

'

'

'

'

Covenant Ratio Debt To Ebitda

'

'

'

'

'

'

'

'

5

'

'

'

'

'

'

'

'

Covenant Ratio Debt To Ebitda Post Acquisition

'

'

'

'

'

'

'

'

5.5

'

'

'

'

'

'

'

'

Line of Credit Facility, Expiration Date

'

'

'

'

'

'

'

'

'

'

'

'3 years

'

'

'

'

'

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Net cash provided by operating activities included:	'		'		'
Interest paid (net of amounts capitalized)	$161		$67		$5
Net income taxes paid to taxing authorities	1,099	[1]	1,211	[1]	617	[1]
Income taxes paid to Marathon Oil under tax sharing agreement	'		181		'
Non-cash investing and financing activities:	'		'		'
Capital lease obligations increase	61		62		26
Non-cash contributions from Marathon Oil(a)	43		0		0
Preferred equity interest received in contract settlement	0		45	[2]	0
Preferred equity interest dividend received in-kind	0		1		0
Acquisitions:	'		'		'
Contingent consideration	600	[3]	0		0
Payable to seller	6	[3]	0		0
Intangible asset acquired	0		3		0
Liability assumed	0		2		0
Marathon Oil Companies [Member]	'		'		'
Non-cash investing and financing activities:	'		'		'
Property, Plant and Equipment contributed by Marathon Oil	0		0		81
Non-cash contributions from Marathon Oil(a)	'		'		$57	[4]
[1]	U.S. and most state income taxes, if incurred, were paid by Marathon Oil for periods prior to the Spinoff. The amount for 2012 includes payments of $181 million for 2011 return period income taxes made to Marathon Oil under our tax sharing agreement, and in return we received an equal amount of tax credits. See Note 25.
[2]	See Note 6.
[3]	See Note 5.
[4]	See Note 7.

Supplemental_Cash_Flow_Informa3

Supplemental Cash Flow Information (Reconciliation Of Additions To Property, Plant And Equipment To Total Capital Expenditures) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Schedule of Reconciliation of Additions to Property Plant and Equipment [Line Items]	'		'		'
Additions to property, plant and equipment	$1,206,000,000		$1,369,000,000		$1,185,000,000
Acquisitions	1,386,000,000	[1]	180,000,000	[1]	74,000,000	[1]
Increase (decrease) in capital accruals	73,000,000		-117,000,000		53,000,000
Total capital expenditures	2,665,000,000		1,432,000,000		1,312,000,000
Galveston Bay Refinery And Related Assets [Member]	'		'		'
Schedule of Reconciliation of Additions to Property Plant and Equipment [Line Items]	'		'		'
Acquisitions	1,360,000,000		'		'
Cash paid excluding inventories	1,150,000,000		'		'
Assumed liabilities	$210,000,000		'		'
[1]	Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The 2012 acquisitions exclude the inventory acquired and liability assumed. See Note 5.

Supplemental_Cash_Flow_Informa4

Supplemental Cash Flow Information (Reconciliation Of Contributions From (Distributions To) Marathon Oil) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Cash Flow Information [Line Items]	'	'	'
Distributions to Marathon Oil per consolidated statements of cash flows	$0	$0	($783)
Non-cash contributions from Marathon Oil(a)	43	0	0
Distributions to Marathon Oil per consolidated statements of equity / net investment	'	'	-726
Marathon Oil Companies [Member]	'	'	'
Supplemental Cash Flow Information [Line Items]	'	'	'
Non-cash contributions from Marathon Oil(a)	'	'	$57	[1]
[1]	See Note 7.

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Loss (Changes in Accumulated Other Comprehensive Loss by Component) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'	'
Balance as of December 31, 2012	($464)		'	'
Other comprehensive income (loss) before reclassifications	189		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Amortization – prior service credit	-49	[1]	'	'
Amortization– actuarial loss	69	[1]	'	'
Amortization– settlement loss	95	[1]	'	'
Other	-1	[2]	'	'
Tax expense	-43		'	'
Other comprehensive income (loss)	260		415	-245
Balance as of December 31, 2013	-204		-464	'
Pension Benefits [Member]	'		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Amortization – prior service credit	-45		-18	6
Amortization– actuarial loss	161		218	79
Other Benefits [Member]	'		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Amortization – prior service credit	-4		-2	0
Amortization– actuarial loss	3		2	0
Accumulated Defined Benefit Plans Adjustment [Member] | Pension Benefits [Member]	'		'	'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'	'
Balance as of December 31, 2012	-432		'	'
Other comprehensive income (loss) before reclassifications	198		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Amortization – prior service credit	-45	[1]	'	'
Amortization– actuarial loss	66	[1]	'	'
Amortization– settlement loss	95	[1]	'	'
Tax expense	-43		'	'
Other comprehensive income (loss)	271		'	'
Balance as of December 31, 2013	-161		'	'
Accumulated Defined Benefit Plans Adjustment [Member] | Other Benefits [Member]	'		'	'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'	'
Balance as of December 31, 2012	-36		'	'
Other comprehensive income (loss) before reclassifications	-13		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Amortization – prior service credit	-4	[1]	'	'
Amortization– actuarial loss	3	[1]	'	'
Amortization– settlement loss	0	[1]	'	'
Tax expense	0		'	'
Other comprehensive income (loss)	-14		'	'
Balance as of December 31, 2013	-50		'	'
Gain Cash Flow Hedge [Member]	'		'	'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'	'
Balance as of December 31, 2012	4		'	'
Other comprehensive income (loss) before reclassifications	0		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Tax expense	0		'	'
Other comprehensive income (loss)	0		'	'
Balance as of December 31, 2013	4		'	'
Workers Compensation [Member]	'		'	'
Accumulated Other Comprehensive Income (Loss) [Roll Forward]	'		'	'
Balance as of December 31, 2012	0		'	'
Other comprehensive income (loss) before reclassifications	4		'	'
Amounts reclassified from accumulated other comprehensive loss:	'		'	'
Other	-1	[2]	'	'
Tax expense	0		'	'
Other comprehensive income (loss)	3		'	'
Balance as of December 31, 2013	$3		'	'
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 22.
[2]	This amount was reclassified out of accumulated other comprehensive loss and is included in selling, general and administrative expenses on the consolidated statements of income.

Recovered_Sheet1

Defined Benefit Pension And Other Postretirement Plans (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Accumulated benefit obligation	$1,912	$2,035	'
Defined benefit plan investment goals	'The overall expected long-term return on plan assets assumption is determined based on an asset rate-of-return modeling tool developed by a third-party investment group. The tool utilizes underlying assumptions based on actual returns by asset category and inflation and takes into account our asset allocation to derive an expected long-term rate of return on those assets. Capital market assumptions reflect the long-term capital market outlook. The assumptions for equity and fixed income investments are developed using a building-block approach, reflecting observable inflation information and interest rate information available in the fixed income markets. Long-term assumptions for other asset categories are based on historical results, current market characteristics and the professional judgment of our internal and external investment teams.	'	'
Defined Benefit Plan, Diversification	'The asset allocation strategy will change over time in response to changes primarily in funded status, which is dictated by current and anticipated market conditions, the independent actions of our investment committee, required cash flows to and from the plans and other factors deemed appropriate. Such changes in asset allocation are intended to allocate additional assets to the fixed income asset class should the funded status improve. The fixed income asset class shall be invested in such a manner that its interest rate sensitivity correlates highly with that of the plans' liabilities. Other asset classes are intended to provide additional return with associated higher levels of risk.	'	'
Plan investment policies and strategies	'Investment performance and risk is measured and monitored on an ongoing basis through quarterly investment meetings and periodic asset and liability studies.	'	'
Contributions to defined contribution plans	76	60	60
Multiemployer Plans, Pension [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
The Company's contributions to multiemployer plans	3	4	3
Equity Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Targeted asset allocation	62.00%	'	'
Fixed Income Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Targeted asset allocation	38.00%	'	'
Pension And Postretirement Healthcare Plan [Member] | Galveston Bay Refinery And Related Assets [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Decrease in laibilities	-122	'	'
Percentage increase in discount rate	0.20%	'	'
Liability related to retiree medical assumed at the acquisition date	43	'	'
Pension Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Decrease in benefit liabilities	'	537	'
Increase in retiree medical liabilities resulting from a reduction in discount rates	183	-117	'
Estimated net gain (loss) that will be amortized from accumulated other comprehensive loss in 2014	52	'	'
Estimated prior service cost that will be amortized from accumulated other comprehensive loss in 2014	46	'	'
Pension Contributions	161	'	'
Pension Benefits [Member] | Funded Pension Plans [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Defined benefit plans, estimated future employer contributions in next fiscal year	0	'	'
Pension Benefits [Member] | Unfunded Pension Plans [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Defined benefit plans, estimated future employer contributions in next fiscal year	18	'	'
Health Plan [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Decrease in benefit liabilities	'	40	'
Increase in retiree medical liabilities resulting from a reduction in discount rates	'	57	'
Health Plan [Member] | Maximum [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Maximum increase in tax-free contributions to health reimbursement account (in percentage)	'	4.00%	'
Other Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Increase in retiree medical liabilities resulting from a reduction in discount rates	-17	-53	'
Estimated net gain (loss) that will be amortized from accumulated other comprehensive loss in 2014	3	'	'
Estimated prior service cost that will be amortized from accumulated other comprehensive loss in 2014	4	'	'
Other Benefits [Member] | Unfunded Pension Plans [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Defined benefit plans, estimated future employer contributions in next fiscal year	26	'	'
Other Pension Plans [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Multi employer pension plans	'There have been no significant changes that affect the comparability of 2013, 2012 and 2011 contributions.	'	'
Other Pension Plans [Member] | Multiemployer Plans, Pension [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Number of multiemployer defined benefit pension or health and welfare plan	'	1	'
Other Pension Plans [Member] | Maximum [Member] | Multiemployer Plans, Pension [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Funded percentage of plans in red zone	65.00%	'	'
Marathon Petroleum's contributions as a percentage of total contributions to the multi-employer pension plan, maximum	5.00%	'	'
Health Plans [Member] | Multiemployer Health And Welfare Plan [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Number of multiemployer defined benefit pension or health and welfare plan	'	1	'
The Company's contributions to multiemployer plans	$5	$5	$4

Recovered_Sheet2

Defined Benefit Pension And Other Postretirement Plans (Summary Of Defined Benefit Plans With Accumulated Benefit Obligations In Excess Of Plan Assets) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]	'	'
Projected benefit obligations	$1,927	$2,192
Accumulated benefit obligations	1,912	2,035
Fair value of plan assets	$1,800	$1,478

Defined_Benefit_Pension_And_Ot2

Defined Benefit Pension And Other Postretirement Plans (Summary Of Projected Benefit Obligations And Funded Status For Defined Benefit Pension And Other Postretirement Plans) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Change in plan assets:	'		'		'
Fair value of plan assets at December 31	$1,800		$1,478		'
Amounts recognized in the consolidated balance sheets:	'		'		'
Noncurrent liabilities	-771		-1,266		'
LOOP [Member]	'		'		'
Pretax amounts recognized in accumulated other comprehensive loss:	'		'		'
Equity method investments, Ownership Percentage	51.00%		'		'
LOOP [Member]	'		'		'
Pretax amounts recognized in accumulated other comprehensive loss:	'		'		'
Equity method investments, Ownership Percentage	51.00%		'		'
Pension Benefits [Member]	'		'		'
Change in benefit obligations:	'		'		'
Benefit obligations at January 1	2,192		2,685		'
Service cost	93		66		65
Interest cost	73		94		110
Actuarial (gain) loss	-183		117		'
Liability gain due to curtailment	0		-17		'
Other	0	[1]	-520	[1]	'
Benefit obligations at December 31	1,927		2,192		2,685
Change in plan assets:	'		'		'
Fair value of plan assets at January 1	1,478		1,423		'
Actual return on plan assets	241		157		'
Employer contributions	329		131		'
Benefits paid	-248		-233		'
Fair value of plan assets at December 31	1,800		1,478		1,423
Funded status of plans at December 31	-127		-714		'
Amounts recognized in the consolidated balance sheets:	'		'		'
Current liabilities	-18		-18		'
Noncurrent liabilities	-109		-696		'
Accrued benefit cost	-127		-714		'
Pretax amounts recognized in accumulated other comprehensive loss:	'		'		'
Net loss	668	[2]	1,147	[2]	'
Prior service cost (credit)	-415	[2]	-460	[2]	'
Pension Benefits [Member] | LOOP [Member]	'		'		'
Pretax amounts recognized in accumulated other comprehensive loss:	'		'		'
Net loss	16	[2]	'		'
Other Benefits [Member]	'		'		'
Change in benefit obligations:	'		'		'
Benefit obligations at January 1	591		551		'
Service cost	25		20		19
Interest cost	26		24		27
Actuarial (gain) loss	17		53		'
Liability gain due to curtailment	0		0		'
Other	48	[1]	-40	[1]	'
Benefit obligations at December 31	687		591		551
Change in plan assets:	'		'		'
Benefits paid	-20		-17		'
Funded status of plans at December 31	-687		-591		'
Amounts recognized in the consolidated balance sheets:	'		'		'
Current liabilities	-25		-21		'
Noncurrent liabilities	-662		-570		'
Accrued benefit cost	-687		-591		'
Pretax amounts recognized in accumulated other comprehensive loss:	'		'		'
Net loss	107	[2]	93	[2]	'
Prior service cost (credit)	-30	[2]	-38	[2]	'
Other Benefits [Member] | LOOP [Member]	'		'		'
Pretax amounts recognized in accumulated other comprehensive loss:	'		'		'
Net loss	$2	[2]	'		'
[1]	Includes adjustments related to plan amendments in 2013 and 2012. Also, includes adjustments related to the Galveston Bay Refinery and Related Assets acquisition in 2013.
[2]	Amounts exclude those related to LOOP, an equity method investee with defined benefit pension and postretirement plans for which net losses of $16 million and $2 million were recorded in accumulated other comprehensive loss in 2013, reflecting our 51 percent share.

Defined_Benefit_Pension_And_Ot3

Defined Benefit Pension And Other Postretirement Plans (Components Of Net Periodic Benefit Cost And Other Comprehensive Loss) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):	'		'		'
Amortization of actuarial loss	($69)	[1]	'		'
Amortization of prior service cost (credit)	49	[1]	'		'
Pension Benefits [Member]	'		'		'
Components of net periodic benefit cost:	'		'		'
Service cost	93		66		65
Interest cost	73		94		110
Expected return on plan assets	-107		-104		-97
Amortization - prior service cost (credit)	-45		-18		6
Amortization - actuarial loss	66		93		71
Amortization - net settlement/curtailment loss	95	[2]	125	[2]	8	[2]
Net periodic benefit cost	175	[3]	256	[3]	163	[3]
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):	'		'		'
Actuarial (gain) loss	-317		46		427
Prior service cost (credit)	0	[4]	-520	[4]	0	[4]
Amortization of actuarial loss	-161		-218		-79
Amortization of prior service cost (credit)	45		18		-6
Other	0	[5]	0	[5]	6	[5]
Total recognized in other comprehensive loss	-433		-674		348
Total recognized in net periodic benefit cost and other comprehensive loss	-258		-418		511
Other Benefits [Member]	'		'		'
Components of net periodic benefit cost:	'		'		'
Service cost	25		20		19
Interest cost	26		24		27
Expected return on plan assets	0		0		0
Amortization - prior service cost (credit)	-4		-2		0
Amortization - actuarial loss	3		2		0
Amortization - net settlement/curtailment loss	0	[2]	0	[2]	0	[2]
Net periodic benefit cost	50	[3]	44	[3]	46	[3]
Other changes in plan assets and benefit obligations recognized in other comprehensive loss (pretax):	'		'		'
Actuarial (gain) loss	17		53		39
Prior service cost (credit)	4	[4]	-40	[4]	0	[4]
Amortization of actuarial loss	-3		-2		0
Amortization of prior service cost (credit)	4		2		0
Other	0	[5]	0	[5]	0	[5]
Total recognized in other comprehensive loss	22		13		39
Total recognized in net periodic benefit cost and other comprehensive loss	$72		$57		$85
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 22.
[2]	A curtailment gain was recorded in 2011 on the Speedway pension plan at the end of the transition services period related to the sale of most of our Minnesota Assets in 2010. See Note 6.
[3]	Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
[4]	Includes adjustments due to plan amendments approved in 2013 and adjustments due to changes made to the defined pension plans and the post-65 medical plan coverage effective January 1, 2013.
[5]	Includes adjustments related to the Spinoff in 2011.

Defined_Benefit_Pension_And_Ot4

Defined Benefit Pension And Other Postretirement Plans (Summary Of Assumptions Used To Determine Benefit Obligations And Net Periodic Benefit Cost) (Detail)

12 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Other Benefits [Member]

Other Benefits [Member]

Other Benefits [Member]

Scenario, Forecast [Member]

Weighted-average assumptions used to determine benefit obligation:

'

'

'

'

'

'

'

Weighted-average assumptions used to determine benefit obligation, Discount rate

4.30%

3.45%

4.30%

'

4.95%

4.05%

4.65%

Weighted-average assumptions used to determine benefit obligation, Rate of compensation increase

3.70%

5.00%

5.00%

'

3.70%

5.00%

5.00%

Weighted average assumptions used to determine net periodic benefit cost:

'

'

'

'

'

'

'

Weighted average assumptions used to determine net periodic benefit cost, Discount rate

3.88%

4.06%

4.98%

'

4.11%

4.54%

5.55%

Weighted average assumptions used to determine net periodic benefit cost, Expected long-term return on plan assets

7.50%

[1]

7.50%

[1]

8.50%

[1]

7.00%

[1]

0.00%

[1]

0.00%

[1]

0.00%

[1]

Weighted average assumptions used to determine net periodic benefit cost, Rate of compensation increase

5.00%

5.00%

5.00%

'

5.00%

5.00%

5.00%

[1]

Effective January 1, 2014, the expected long-term rate of return on plan assets changed from 7.50 percent to 7.00 percent

Defined_Benefit_Pension_And_Ot5

Defined Benefit Pension And Other Postretirement Plans (Summarizes Assumed Health Care Cost Trend Rates) (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Medical, Pre-65 [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Health care cost trend rate assumed for the following year	8.00%	8.00%	7.50%
Rate to which the cost trend rate is assumed to decline	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	'2020	'2020	'2018
Medical, Post-65 [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Health care cost trend rate assumed for the following year	'	'	7.00%	[1]
Rate to which the cost trend rate is assumed to decline	'	'	5.00%	[1]
Year that the rate reaches the ultimate trend rate	'	'	'2017	[1]
Medical, Post-65 [Member] | Maximum [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Health care cost trend rate assumed for the following year	4.00%	'	'
Prescription Drugs [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Health care cost trend rate assumed for the following year	7.00%	7.00%	7.50%
Rate to which the cost trend rate is assumed to decline	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	'2018	'2018	'2018
[1]	Effective 2013, as a result of changes in the post-65 medical plan coverage of the Marathon Petroleum Health Plan and the Marathon Petroleum Retiree Health Plan, increases are the lower of the trend rate or 4 percent.

Defined_Benefit_Pension_And_Ot6

Defined Benefit Pension And Other Postretirement Plans (Effects Of One Percentage Point Change In Assumed Health Care Cost Trend Rates) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]	'
Effect on total of service and interest cost components, 1-Percentage-Point-Increase	$5
Effect on other postretirement benefit obligations, 1-Percentage-Point-Increase	39
Effect on total of service and interest cost components, 1-Percentage-Point Decrease	-4
Effect on other postretirement benefit obligations, 1-Percentage-Point-Decrease	($34)

Defined_Benefit_Pension_And_Ot7

Defined Benefit Pension And Other Postretirement Plans (Fair Values Of Defined Benefit Pension Plan Assets) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	$1,800	$1,478	'
Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	189	107	'
Equity Investments, Common Stocks [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	69	'	'
Equity Funds, Mutual Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	217	'	'
Exchange-Traded Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	166	'
Investment Trusts [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	111	'
Equity Funds, Pooled Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	590	709	'
Fixed Income, Corporate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	356	'	'
Fixed Income, Government [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	22	'	'
Fixed Income, Pooled Funds [Member] [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	218	258	'
Private Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	57	56	'
Real Estate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	60	54	'
Other [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	22	17	'
Level 1 [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	288	290	'
Level 1 [Member] | Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	107	'
Level 1 [Member] | Equity Investments, Common Stocks [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	69	'	'
Level 1 [Member] | Equity Funds, Mutual Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	217	'	'
Level 1 [Member] | Exchange-Traded Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	166	'
Level 1 [Member] | Investment Trusts [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	17	'
Level 1 [Member] | Equity Funds, Pooled Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 1 [Member] | Fixed Income, Corporate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 1 [Member] | Fixed Income, Government [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 1 [Member] | Fixed Income, Pooled Funds [Member] [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 1 [Member] | Private Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 1 [Member] | Real Estate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 1 [Member] | Other [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	2	0	'
Level 2 [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	1,375	1,061	'
Level 2 [Member] | Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	189	0	'
Level 2 [Member] | Equity Investments, Common Stocks [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 2 [Member] | Equity Funds, Mutual Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 2 [Member] | Exchange-Traded Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	0	'
Level 2 [Member] | Investment Trusts [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	94	'
Level 2 [Member] | Equity Funds, Pooled Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	590	709	'
Level 2 [Member] | Fixed Income, Corporate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	356	'	'
Level 2 [Member] | Fixed Income, Government [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	22	'	'
Level 2 [Member] | Fixed Income, Pooled Funds [Member] [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	218	258	'
Level 2 [Member] | Private Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 2 [Member] | Real Estate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 2 [Member] | Other [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 3 [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	137	127	121
Level 3 [Member] | Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 3 [Member] | Equity Investments, Common Stocks [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 3 [Member] | Equity Funds, Mutual Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 3 [Member] | Exchange-Traded Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	0	'
Level 3 [Member] | Investment Trusts [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	'	0	'
Level 3 [Member] | Equity Funds, Pooled Funds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 3 [Member] | Fixed Income, Corporate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 3 [Member] | Fixed Income, Government [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	'	'
Level 3 [Member] | Fixed Income, Pooled Funds [Member] [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	0	0	'
Level 3 [Member] | Private Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	57	56	55
Level 3 [Member] | Real Estate [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	60	54	49
Level 3 [Member] | Other [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Plan Asset Investments, at fair value	$20	$17	$17

Defined_Benefit_Pension_And_Ot8

Defined Benefit Pension And Other Postretirement Plans (Reconciliation Of Beginning And Ending Balances Of Plan Assets Classified As Level 3) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Actual return on plan assets:	'	'
Fair value of plan assets at December 31	$1,800	$1,478
Level 3 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at January 1	127	121
Actual return on plan assets:	'	'
Net realized gains/(losses)	16	3
Net unrealized gains/(losses)	16	-1
Purchases	12	22
Sales	-34	-18
Fair value of plan assets at December 31	137	127
Private Equity [Member]	'	'
Actual return on plan assets:	'	'
Fair value of plan assets at December 31	57	56
Private Equity [Member] | Level 3 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at January 1	56	55
Actual return on plan assets:	'	'
Net realized gains/(losses)	13	5
Net unrealized gains/(losses)	3	-3
Purchases	7	12
Sales	-22	-13
Fair value of plan assets at December 31	57	56
Real Estate [Member]	'	'
Actual return on plan assets:	'	'
Fair value of plan assets at December 31	60	54
Real Estate [Member] | Level 3 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at January 1	54	49
Actual return on plan assets:	'	'
Net realized gains/(losses)	3	-2
Net unrealized gains/(losses)	10	2
Purchases	5	10
Sales	-12	-5
Fair value of plan assets at December 31	60	54
Other [Member]	'	'
Actual return on plan assets:	'	'
Fair value of plan assets at December 31	22	17
Other [Member] | Level 3 [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Fair value of plan assets at January 1	17	17
Actual return on plan assets:	'	'
Net realized gains/(losses)	0	0
Net unrealized gains/(losses)	3	0
Purchases	0	0
Sales	0	0
Fair value of plan assets at December 31	$20	$17

Defined_Benefit_Pension_And_Ot9

Defined Benefit Pension And Other Postretirement Plans (Estimated Future Benefit Payments) (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Pension Benefits [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
2014	$186
2015	181
2016	177
2017	178
2018	175
2019 through 2023	814
Other Benefits [Member]	'
Defined Benefit Plan Disclosure [Line Items]	'
2014	26	[1]
2015	29	[1]
2016	32	[1]
2017	34	[1]
2018	38	[1]
2019 through 2023	$231	[1]
[1]	Effective 2013, as a result of the Patient Protection and Affordable Care Act, future Medicare reimbursements will no longer be tax deductible and must be used to reduce the costs of providing Medicare part D equivalent prescription drug benefits to retirees.

Recovered_Sheet3

Defined Benefit Pension And Other Postretirement Plans (Multi Employer Pension Plan) (Detail) (Multiemployer Plans, Pension [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Employees
Multiemployer Plans, Pension [Member]	'	'	'
Multiemployer Plans [Line Items]	'	'	'
MPC Contributions	$3,000,000	$4,000,000	$3,000,000
Multiemployer pension plan, minimum contribution requirement per week per employee	$269	'	'
Number of employees participated in the plan	257	'	'

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans (Narrative) (Detail) (USD $)

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Jun. 30, 2011

Jun. 30, 2011

Jun. 30, 2011

Dec. 31, 2013

Jun. 30, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Stock Appreciation Rights (SARs) [Member]

Restricted Stock Awards and Restricted Stock Units [Member]

Performance Units [Member]

Performance Unit Awards [Member]

Performance Unit Awards [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Restricted Stock Units [Member]

Predecessor [Member]

Predecessor [Member]

Predecessor [Member]

MPC 2007 and 2003 Plans [Member]

MPC 2007 and 2003 Plans [Member]

MPC 2011 Plan [Member]

MPC 2012 and 2011 Plans [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Non-Employee Directors [Member]

Restricted Stock [Member]

Restricted Stock Units [Member]

Employees

Predecessor [Member]

Performance Units [Member]

Performance Units [Member]

Stock Options [Member]

Stock Appreciation Rights (SARs) [Member]

Performance Units [Member]

MPC 2012 Plan [Member]

MPC 2012 Plan [Member]

MPC 2012 Plan [Member]

Stock Options [Member]

Awards Other Than Stock Options Or Stock Appreciation Rights [Member]

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares of common stock authorized to be delivered under the compensation plan

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25,000,000

10,000,000

10,000,000

Number of employees affected by adjustment and substitution of awards

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

393

'

'

'

'

'

'

'

'

'

'

Stock options maximum term, in years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'10 years

'10 years

'

'

'

'

Vesting period of awards

'

'

'

'

'

'

'3 years

'3 years

'3 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'30 months

'36 months

'

'

'

'

'

'

'

Restricted stock and restricted stock unit awards granted in 2012, additional holding period

'

'

'

'

'

'

'

'

'1 year

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Target payout

'

'

'

'

'

'

'

'

'

$1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Actual payout

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2

'

'

'

Target payout percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

200.00%

'

'

'

Pay-out percentage in MPC common stock (in percentage)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25.00%

'

'

'

'

'

'

'

Pay-out percentage in cash (in percentage)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

75.00%

'

'

'

'

'

'

'

Grant date fair value

'

'

'

'

'

'

'

'

'

'

$1.12

$1.09

$41.54

$87.06

$43.11

$33.78

$73.48

$44.38

'

'

$48.53

$45.22

'

'

'

'

'

'

'

'

'

'

'

Total employee stock-based compensation expense

'

$42,000,000

$35,000,000

$28,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total related income tax benefits

'

15,000,000

13,000,000

11,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash received upon exercise of stock option awards

1,000,000

48,000,000

108,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

17,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Tax benefits realized by MPC for deductions for stock awards exercised

'

18,000,000

16,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,000,000

'

'

'

'

'

'

1,000,000

'

'

'

'

'

'

Share-based compensation arrangement by share-based payment award fair value assumptions expected volatility rate - Company stock weighting

'

33.00%

'

'

'

33.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based compensation arrangement by share-based payment award fair value assumptions expected volatility rate - Peer stock weighting

'

67.00%

'

'

'

67.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Intrinsic value of options exercised

'

'

'

'

1,000,000

60,000,000

37,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

18,000,000

'

'

'

'

'

'

'

'

'

Unrecognized compensation cost

'

'

'

'

'

7,000,000

'

'

'

'

'

'

'

24,000,000

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average recognition period, in years

'

'

'

'

'

'8 months 12 days

'

'

'

'

'

'

'

'1 year 3 months 18 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted units outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

385,079

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted units vested

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

383,953

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average fair value, vested

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$33.89

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares issued in period

'

'

'

'

'

'

'

'

'

'

41,671

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans (Weighted Average Assumptions Used To Value Stock Options Awards) (Detail) (Stock Options [Member], USD $)	6 Months Ended	12 Months Ended		6 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011
				Predecessor [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Weighted average exercise price per share	$36.18	$84.65	$42.02	$51.93
Expected annual dividends per share	$0.95	$1.40	$1	$1
Expected life in years	'5 years 9 months 18 days	'6 years	'5 years 9 months 18 days	'5 years 3 months 18 days
Expected volatility	48.00%	40.00%	47.00%	40.00%
Risk-free interest rate	1.40%	1.00%	1.10%	2.00%
Weighted average grant date fair value of stock option awards granted	$13.08	$27.13	$14.45	$16.73

StockBased_Compensation_Plans_3

Stock-Based Compensation Plans (Summary Of Stock Option Award Activity) (Detail) (Stock Options [Member], USD $)	6 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013		Dec. 31, 2012
Stock Options [Member]	'	'		'
Number of of Shares	'	'		'
Outstanding at December 31, 2012	'	6,172,194	[1]	'
Granted	'	408,603	[1]	'
Exercised	'	-1,348,938	[1]	'
Forfeited, canceled or expired	'	-84,022	[1]	'
Outstanding at December 31, 2013	'	5,147,837	[1]	6,172,194	[1]
Vested and expected to vest at December 31, 2013	'	5,142,351	[1]	'
Exercisable at December 31, 2013	'	3,674,485	[1]	'
Weighted Average Exercise Price	'	'		'
Outstanding at December 31, 2012 (in USD per share)	'	$36.17		'
Granted (in USD per share)	$36.18	$84.65		$42.02
Exercised (in USD per share)	'	$35.48		'
Forfeited, canceled or expired (in USD per share)	'	$43.97		'
Outstanding at December 31, 2013 (in USD per share)	'	$40.08		$36.17
Vested and expected to vest at December 31, 2013 (in USD per share)	'	$40.04		'
Exercisable at December 31, 2013 (in USD per share)	'	$34.63		'
Weighted Average Remaining Contractual Term	'	'		'
Vested and expected to vest at December 31, 2013 (in years)	'	'6 years		'
Exercisable at December 31, 2013 (in years)	'	'5 years 3 months 18 days		'
Aggregate Intrinsic Value	'	'		'
Vested and expected to vest at December 31, 2013 (in USD)	'	$266		'
Exercisable at December 31, 2013 (in USD)	'	$210		'
[1]	(a) Includes an immaterial number of stock appreciation rights.

StockBased_Compensation_Plans_4

Stock-Based Compensation Plans (Summary Of Restricted Stock Award Activity) (Detail) (USD $)	6 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock [Member]	'	'	'
Number of Shares	'	'	'
Outstanding December 31, 2012	'	638,073	'
Granted	'	256,224	'
RS's Vested/RSU's Issued	'	-245,116	'
Forfeited	'	-25,059	'
Outstanding December 31, 2013	'	624,122	638,073
Weighted Average Grant Date Fair Value	'	'	'
Outstanding at December 31, 2012	'	$40.83	'
Granted (in USD per share)	$41.54	$87.06	$43.11
RS's Vested/RSU's Issued (in USD per share)	'	$37.95	'
Forfeited (in USD per share)	'	$58.60	'
Outstanding at December 31, 2013	'	$61.11	$40.83
Restricted Stock Units [Member]	'	'	'
Number of Shares	'	'	'
Outstanding December 31, 2012	'	359,111	'
Granted	'	26,399	'
RS's Vested/RSU's Issued	'	-431	'
Forfeited	'	0	'
Outstanding December 31, 2013	'	385,079	359,111
Weighted Average Grant Date Fair Value	'	'	'
Outstanding at December 31, 2012	'	$31.07	'
Granted (in USD per share)	$33.78	$73.48	$44.38
RS's Vested/RSU's Issued (in USD per share)	'	$39.53	'
Forfeited (in USD per share)	'	$0	'
Outstanding at December 31, 2013	'	$33.96	$31.07

StockBased_Compensation_Plans_5

Stock-Based Compensation Plans (Summary Of Values Related To Vested And Unvested Restricted Stock Awards) (Detail) (USD $)	6 Months Ended	12 Months Ended		6 Months Ended		12 Months Ended		6 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011
	Restricted Stock [Member]	Restricted Stock [Member]	Restricted Stock [Member]	Restricted Stock [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]	Restricted Stock Units [Member]
				Predecessor [Member]				Predecessor [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'
Intrinsic Value of Awards Vesting During the Period	$1	$20	$5	$3	$0	$0	$0	$0
Weighted Average Grant Date Fair Value of Awards Granted During the Period (in USD per share)	$41.54	$87.06	$43.11	$48.53	$33.78	$73.48	$44.38	$45.22

StockBased_Compensation_Plans_6

Stock-Based Compensation Plans (Summary Of Performance Unit Awards) (Detail) (Performance Unit Awards [Member])	12 Months Ended
	Dec. 31, 2013
Performance Unit Awards [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Outstanding December 31, 2012	2,040,000
Granted	1,782,500
Settled	0
Canceled	0
Outstanding December 31, 2013	3,822,500

Leases_Schedule_Of_Future_Mini

Leases (Schedule Of Future Minimum Commitments) (Detail) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]	'
Capital Lease Obligations, 2014	$51
Capital Lease Obligations, 2015	52
Capital Lease Obligations, 2016	51
Capital Lease Obligations, 2017	50
Capital Lease Obligations, 2018	49
Capital Lease Obligations, Later years	345
Total minimum capital lease payments	598
Less imputed interest costs	-203
Present value of net minimum lease payments	395
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]	'
Operating Lease Obligations, 2014	191
Operating Lease Obligations, 2015	184
Operating Lease Obligations, 2016	152
Operating Lease Obligations, 2017	106
Operating Lease Obligations, 2018	95
Operating Lease Obligations, Later years	241
Total minimum operating lease payments	$969

Leases_Schedule_Of_Operating_L

Leases (Schedule Of Operating Lease Rental Expense) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Leases [Abstract]	'	'	'
Minimum rental	$213	$139	$123
Contingent rental	0	0	1
Rental expense	$213	$139	$124

Commitments_And_Contingencies_

Commitments And Contingencies (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]	'	'
Accrued liabilities for remediation	$123,000,000	$123,000,000
Receivables for recoverable costs	51,000,000	51,000,000
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	1,700,000,000	1,400,000,000
Galveston Bay Refinery And Related Assets [Member]	'	'
Loss Contingencies [Line Items]	'	'
Maximum earnout provision payable to the company	700,000,000	'
Indemnification Agreement [Member] | Marathon Oil Companies [Member]	'	'
Loss Contingencies [Line Items]	'	'
Guarantee obligation current carrying value	2,000,000	'
Equity Method Investees [Member] | Other Guarantees [Member]	'	'
Loss Contingencies [Line Items]	'	'
Maximum potential undiscounted payments	122,000,000	'
Guarantee obligations maximum exposure per event	50,000,000	'
North Dakota Pipeline [Member]	'	'
Loss Contingencies [Line Items]	'	'
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	892,000,000	'
Guarantee of Indebtedness of Others [Member] | LOOP and LOCAP LLC [Member] | Financial Guarantee [Member]	'	'
Loss Contingencies [Line Items]	'	'
Line of credit facility, expiration date	31-Dec-37	'
Maximum potential undiscounted payments	172,000,000	'
Master Shelf Agreement [Member] | Centennial [Member] | Financial Guarantee [Member]	'	'
Loss Contingencies [Line Items]	'	'
Line of credit facility, expiration date	31-Dec-24	'
Maximum potential undiscounted payments	42,000,000	'
Standby Letters Of Credit [Member] | TAME [Member] | Financial Guarantee [Member]	'	'
Loss Contingencies [Line Items]	'	'
Line of credit facility, expiration date	31-Dec-18	'
Maximum potential undiscounted payments	25,000,000	'
Reimbursement percent	50.00%	'
Emergency Pricing And Consumer Protection Laws [Member] | Pending Or Threatened Litigation [Member]	'	'
Loss Contingencies [Line Items]	'	'
Alleged amount overcharged from customers	$89,000,000	'
Emergency Pricing And Consumer Protection Laws [Member] | Pending Or Threatened Litigation [Member] | Kentucky Lawsuit [Member]	'	'
Loss Contingencies [Line Items]	'	'
Loss contingency, inestimable loss	'However, management does not believe the ultimate resolution of this litigation will have a material adverse effect.	'

Subsequent_Event_Details

Subsequent Event (Details) (Felda Iffco Sdn Bhd [Member], Subsequent Event [Member])	12 Months Ended
	Dec. 31, 2013	Feb. 03, 2014
		BPD
Felda Iffco Sdn Bhd [Member] | Subsequent Event [Member]	'	'
Subsequent Event [Line Items]	'	'
Plant capacity (in barrels per day)	'	4,100
Transaction expected close date	'April 2014	'

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Schedule Of Quarterly Financial Information) (Detail) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Revenues	$24,897	$26,256	$25,677	$23,330	$20,686	$21,049	$20,243	$20,265	'	'	'
Income from operations	1,008	301	960	1,156	1,189	1,895	1,307	956	3,425	5,347	3,745
Net income	631	173	599	730	759	1,224	814	596	2,133	3,393	2,389
Net income attributable to MPC	$626	$168	$593	$725	$755	$1,224	$814	$596	$2,112	$3,389	$2,389
Net income attributable to MPC per share	'	'	'	'	'	'	'	'	'	'	'
Basic (in USD per share)	$2.09	$0.54	$1.84	$2.19	$2.26	$3.61	$2.39	$1.71	$6.69	$9.95	$6.70
Diluted (in USD per share)	$2.07	$0.54	$1.83	$2.17	$2.24	$3.59	$2.38	$1.70	$6.64	$9.89	$6.67
Dividends paid per share (in USD per share)	$0.42	$0.42	$0.35	$0.35	$0.35	$0.35	$0.25	$0.25	$1.54	$1.20	$0.45

Supplementary_Statistics_Suppl

Supplementary Statistics (Supplementary Statistics) (Detail) (USD $)

3 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

$1,008,000,000

$301,000,000

$960,000,000

$1,156,000,000

$1,189,000,000

$1,895,000,000

$1,307,000,000

$956,000,000

$3,425,000,000

$5,347,000,000

$3,745,000,000

Minnesota Assets sale settlement gain

'

'

'

'

'

'

'

'

6,000,000

177,000,000

12,000,000

Capital expenditures and investments

'

'

'

'

'

'

'

'

2,789,000,000

[1],[2]

1,460,000,000

[1],[2]

1,323,000,000

[1],[2]

Acquisitions

'

'

'

'

'

'

'

'

1,386,000,000

[3]

180,000,000

[3]

74,000,000

[3]

Fair value of contingent consideration as of acquisition date

'

'

'

'

'

'

'

'

600,000,000

[4]

0

0

Galveston Bay Refinery And Related Assets [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisitions

'

'

'

'

'

'

'

'

1,360,000,000

'

'

Cash paid excluding inventories

'

'

'

'

'

'

'

'

1,150,000,000

'

'

Assumed liabilities

210,000,000

'

'

'

'

'

'

'

210,000,000

'

'

Fair value of contingent consideration as of acquisition date

'

'

'

'

'

'

'

'

600,000,000

'

'

Operating Segments [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

3,791,000,000

[5]

5,624,000,000

[5]

4,061,000,000

[5]

Capital expenditures and investments

'

'

'

'

'

'

'

'

2,624,000,000

[2],[6],[7]

1,256,000,000

[2],[6]

1,185,000,000

[2],[6]

Operating Segments [Member] | Refining & Marketing [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

3,206,000,000

5,098,000,000

3,591,000,000

Capital expenditures and investments

'

'

'

'

'

'

'

'

2,094,000,000

[1],[2],[7]

705,000,000

[1],[2]

900,000,000

[1],[2]

Operating Segments [Member] | Refining & Marketing [Member] | Galveston Bay Refinery And Related Assets [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisitions

'

'

'

'

'

'

'

'

1,290,000,000

'

'

Operating Segments [Member] | Speedway [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

375,000,000

310,000,000

271,000,000

Capital expenditures and investments

'

'

'

'

'

'

'

'

296,000,000

[2],[6],[7],[8]

340,000,000

[2],[6],[8]

164,000,000

[2],[6],[8]

Operating Segments [Member] | Pipeline Transportation [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

210,000,000

[5]

216,000,000

[5]

199,000,000

[5]

Capital expenditures and investments

'

'

'

'

'

'

'

'

234,000,000

[1],[2],[7]

211,000,000

[1],[2]

121,000,000

[1],[2]

Operating Segments [Member] | Pipeline Transportation [Member] | Galveston Bay Refinery And Related Assets [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisitions

'

'

'

'

'

'

'

'

70,000,000

'

'

Operating Segments [Member] | Pipeline Transportation [Member] | MPLX LP [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Cost of Services, Overhead

'

'

'

'

'

'

'

'

20,000,000

4,000,000

'

Corporate, Non-Segment [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Income from operations

'

'

'

'

'

'

'

'

-271,000,000

[10],[5],[9]

-336,000,000

[10],[5],[9]

-316,000,000

[10],[5],[9]

Capital expenditures and investments

'

'

'

'

'

'

'

'

165,000,000

[11],[2]

204,000,000

[11],[2]

138,000,000

[11],[2]

Interest costs capitalized

'

'

'

'

'

'

'

'

28,000,000

101,000,000

114,000,000

Segment Reconciling Items [Member]

'

'

'

'

'

'

'

'

'

'

'

Supplementary Statistics [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Minnesota Assets sale settlement gain

'

'

'

'

'

'

'

'

0

183,000,000

[12]

0

Pension settlement expenses

'

'

'

'

'

'

'

'

($95,000,000)

[13]

($124,000,000)

[13]

$0

[13]

[1]

Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The total consideration amount of $1.15 billion includes the base purchase price and a fair-value estimate of $600 million for the contingent consideration. See Note 5 to the audited consolidated financial statements.

[2]

Capital expenditures include changes in capital accruals.

[3]

Includes $1.36 billion in 2013 for the acquisition of the Galveston Bay Refinery and Related Assets, comprised of total consideration, excluding inventory and other current assets, of $1.15 billion plus assumed liabilities of $210 million. The 2012 acquisitions exclude the inventory acquired and liability assumed. See Note 5.

[4]

See Note 5.

[5]

Included in the Pipeline Transportation segment for 2013 and 2012 are $20 million and $4 million of corporate overhead costs attributable to MPLX, which were included in items not allocated to segments prior to MPLX’s October 31, 2012 initial public offering. These expenses are not currently allocated to other segments.

[6]

Includes Speedway’s acquisition of convenience stores. See Note 5.

[7]

The Refining & Marketing and Pipeline Transportation segments include $1.29 billion and $70 million, respectively, for the acquisition of the Galveston Bay Refinery and Related Assets. See Note 5.

[8]

Includes Speedway's acquisitions of convenience stores. See Note 5 to the audited consolidated financial statements.

[9]

Corporate overhead costs attributable to MPLX were included in the Pipeline Transportation segment subsequent to MPLX’s October 31, 2012 initial public offering.

[10]

Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses, including allocations from the Marathon Oil Companies for periods prior to the Spinoff, and costs related to certain non-operating assets.

[11]

Includes capitalized interest of $28 million, $101 million and $114 million for 2013, 2012 and 2011, respectively.

[12]

See Note 6.

[13]

See Note 22.

Supplementary_Statistics_Opera

Supplementary Statistics (Operating Statistics) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
	BPD		BPD		BPD
Operating Statistics [Line Items ]	'		'		'
MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)	2,086,000	[1],[2]	1,618,000	[1],[2]	1,599,000	[1],[2]
Refining & Marketing [Member]	'		'		'
Operating Statistics [Line Items ]	'		'		'
Refining & Marketing Refined Product Sales Volume (thousands of barrels per day)	2,075,000	[2],[3]	1,599,000	[2],[3]	1,581,000	[2],[3]
Refining & Marketing Gross Margin (dollars per barrel)	13.24	[2],[4]	17.85	[2],[4]	14.26	[2],[4]
Crude Oil Capacity Utilization percent	96.00%	[2],[5]	100.00%	[2],[5]	103.00%	[2],[5]
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	1,802,000	[2],[6]	1,363,000	[2],[6]	1,358,000	[2],[6]
Sour Crude Oil Throughput percent	53.00%	[2]	53.00%	[2]	52.00%	[2]
WTI-Priced Crude Oil Throughput percent	21.00%	[2]	28.00%	[2]	27.00%	[2]
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	1,836,000	[2],[6]	1,386,000	[2],[6]	1,383,000	[2],[6]
Refinery Direct Operating Costs in Refining & Marketing Gross Margin (dollars per barrel): [Abstract]	'		'		'
Turnaround Maintenance And Engineered Project Expenses Per Barrel	1.2	[2],[7]	1	[2],[7]	0.78	[2],[7]
Depreciation and amortization	1.36	[2],[7]	1.44	[2],[7]	1.29	[2],[7]
Other Manufacturing Costs Per Barrel	4.14	[2],[7],[8]	3.15	[2],[7],[8]	3.16	[2],[7],[8]
Total	6.7	[2],[7]	5.59	[2],[7]	5.23	[2],[7]
Pipeline throughput (thousands of barrels per day)(h):	'		'		'
Inter-refinery transfers	36,000		25,000		28,000
Refining & Marketing [Member] | Gulf Coast [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	1,159,000	[2],[9]	'		'
Sour Crude Oil Throughput percent	65.00%	[2]	'		'
WTI-Priced Crude Oil Throughput percent	7.00%	[2]	'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	1,186,000	[2],[9]	'		'
Refinery Direct Operating Costs in Refining & Marketing Gross Margin (dollars per barrel): [Abstract]	'		'		'
Turnaround Maintenance And Engineered Project Expenses Per Barrel	1	[2],[7]	'		'
Depreciation and amortization	1.09	[2],[7]	'		'
Other Manufacturing Costs Per Barrel	3.98	[2],[7],[8]	'		'
Total	6.07	[2],[7]	'		'
Refining & Marketing [Member] | Midwest [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	679,000	[9]	'		'
Sour Crude Oil Throughput percent	35.00%		'		'
WTI-Priced Crude Oil Throughput percent	42.00%		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	686,000	[9]	'		'
Refinery Direct Operating Costs in Refining & Marketing Gross Margin (dollars per barrel): [Abstract]	'		'		'
Turnaround Maintenance And Engineered Project Expenses Per Barrel	1.47	[7]	'		'
Depreciation and amortization	1.74	[7]	'		'
Other Manufacturing Costs Per Barrel	4.21	[7],[8]	'		'
Total	7.42	[7]	'		'
Refining & Marketing [Member] | Crude Oil [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	1,589,000	[2],[6]	1,195,000	[2],[6]	1,177,000	[2],[6]
Refining & Marketing [Member] | Crude Oil [Member] | Gulf Coast [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	964,000	[2],[9]	'		'
Refining & Marketing [Member] | Crude Oil [Member] | Midwest [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	625,000	[9]	'		'
Refining & Marketing [Member] | OtherChargeAndBlendstock [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	213,000	[2],[6]	168,000	[2],[6]	181,000	[2],[6]
Refining & Marketing [Member] | OtherChargeAndBlendstock [Member] | Gulf Coast [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	195,000	[2],[9]	'		'
Refining & Marketing [Member] | OtherChargeAndBlendstock [Member] | Midwest [Member]	'		'		'
Refinery Throughputs (thousands of barrels per day):	'		'		'
Total	54,000	[9]	'		'
Refining & Marketing [Member] | Gasoline [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	921,000	[2],[6]	738,000	[2],[6]	739,000	[2],[6]
Refining & Marketing [Member] | Gasoline [Member] | Gulf Coast [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	551,000	[2],[9]	'		'
Refining & Marketing [Member] | Gasoline [Member] | Midwest [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	371,000	[9]	'		'
Refining & Marketing [Member] | Distillates [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	572,000	[2],[6]	433,000	[2],[6]	433,000	[2],[6]
Refining & Marketing [Member] | Distillates [Member] | Gulf Coast [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	365,000	[2],[9]	'		'
Refining & Marketing [Member] | Distillates [Member] | Midwest [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	207,000	[9]	'		'
Refining & Marketing [Member] | Propane [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	37,000	[2],[6]	26,000	[2],[6]	25,000	[2],[6]
Refining & Marketing [Member] | Propane [Member] | Gulf Coast [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	23,000	[2],[9]	'		'
Refining & Marketing [Member] | Propane [Member] | Midwest [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	14,000	[9]	'		'
Refining & Marketing [Member] | Feedstocks and Special Products [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	221,000	[2],[6]	109,000	[2],[6]	109,000	[2],[6]
Refining & Marketing [Member] | Feedstocks and Special Products [Member] | Gulf Coast [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	215,000	[2],[9]	'		'
Refining & Marketing [Member] | Feedstocks and Special Products [Member] | Midwest [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	41,000	[9]	'		'
Refining & Marketing [Member] | Heavy Fuel Oil [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	31,000	[2],[6]	18,000	[2],[6]	21,000	[2],[6]
Refining & Marketing [Member] | Heavy Fuel Oil [Member] | Gulf Coast [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	19,000	[2],[9]	'		'
Refining & Marketing [Member] | Heavy Fuel Oil [Member] | Midwest [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	12,000	[9]	'		'
Refining & Marketing [Member] | Asphalt [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	54,000	[2],[6]	62,000	[2],[6]	56,000	[2],[6]
Refining & Marketing [Member] | Asphalt [Member] | Gulf Coast [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	13,000	[2],[9]	'		'
Refining & Marketing [Member] | Asphalt [Member] | Midwest [Member]	'		'		'
Refined Product Yields (thousands of barrels per day):	'		'		'
Total	41,000	[9]	'		'
Speedway [Member]	'		'		'
Refinery Direct Operating Costs in Refining & Marketing Gross Margin (dollars per barrel): [Abstract]	'		'		'
Convenience stores at period-end (in number of stores)	1,478		1,464		1,371
Gasoline And Distillate Sales (in millions of gallons)	3,146,000,000		3,027,000,000		2,938,000,000
Gasoline And Distillate Gross Margin (in dollars per gallon)	0.1441	[10]	0.1318	[10]	0.1308	[10]
Merchandise sales (in millions)	3,135		3,058		2,924
Merchandise gross margin (in millions)	825		795		719
Same store gasoline sales volume percentage (period over period)	0.50%		-0.80%		-1.70%
Same store merchandise sales excluding cigarettes percentage (period over period)	4.30%	[11]	7.00%	[11]	6.70%	[11]
Pipeline Transportation [Member]	'		'		'
Pipeline throughput (thousands of barrels per day)(h):	'		'		'
Total	2,191,000	[12]	2,170,000	[12]	2,215,000	[12]
Pipeline Transportation [Member] | Crude Oil Pipelines [Member]	'		'		'
Pipeline throughput (thousands of barrels per day)(h):	'		'		'
Total	1,280,000	[12]	1,190,000	[12]	1,184,000	[12]
Pipeline Transportation [Member] | Refined Products Pipelines [Member]	'		'		'
Pipeline throughput (thousands of barrels per day)(h):	'		'		'
Total	911,000	[12]	980,000	[12]	1,031,000	[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. Starting in the fourth quarter of 2013, direct operating costs are no longer included in the Refining & Marketing gross margin and the gross margin is calculated based on total refinery throughput. All prior periods presented have been recalculated to reflect a consistent approach.
[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 36 thousand barrels per day ("mbpd"), 25 mbpd and 28 mbpd for 2013, 2012 and 2011, 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.