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.