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