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
Number of shares held in treasury (beginning balance) at Dec. 31, 2012		(28)
Number of common shares issued (beginning balance) at Dec. 31, 2012		361
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		1,329				1,318		11
Dividends declared		(229)				(229)
Distributions to noncontrolling interests		(9)						(9)
Other comprehensive loss		210					210
Shares repurchased		(1,313)		(1,413)	100
Shares returned - stock based compensation				(6)
Shares issued - stock based compensation					33
Net shares issued — stock based compensation		27
Stock-based compensation		38			38			0
Tax settlement with Marathon Oil Corporation		39			39
Number of shares issued - stock-based compensation		1
Number of shares repurchased		(17)
Ending balance at Jun. 30, 2013		12,197	4	(2,672)	9,737	4,969	(254)	413
Number of shares held in treasury (ending balance) at Jun. 30, 2013		(45)
Number of common shares issued (ending balance) at Jun. 30, 2013		362
Beginning balance at Dec. 31, 2013		11,332	4	(4,155)	9,768	5,507	(204)	412
Number of shares held in treasury (beginning balance) at Dec. 31, 2013		(65)
Number of common shares issued (beginning balance) at Dec. 31, 2013		362
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		1,071				1,054		17
Dividends declared		(245)				(245)
Distributions to noncontrolling interests		(12)						(12)
Other comprehensive loss		(14)					(14)
Shares repurchased		(1,148)		(1,148)	0
Shares returned - stock based compensation				(10)
Shares issued - stock based compensation					17
Net shares issued — stock based compensation		7
Stock-based compensation		37			37			0
Other		9				9
Number of shares issued - stock-based compensation		1
Number of shares repurchased	[1]	(13)
Ending balance at Jun. 30, 2014		$ 11,037	$ 4	$ (5,313)	$ 9,822	$ 6,325	$ (218)	$ 417
Number of shares held in treasury (ending balance) at Jun. 30, 2014		(78)
Number of common shares issued (ending balance) at Jun. 30, 2014		363

[1] The six months ended June 30, 2013 includes one million shares received under the November 2012 accelerated share repurchase program, which were paid for in 2012.