Goodwill (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Goodwill [Line Items]
Beginning balance, gross		$ 1,911		$ 1,937
Less: accumulated impairment		(1,412)		(1,412)
Goodwill [Roll Forward]
Beginning balance, net	499	525
Dispositions	(40)	(26)
Ending balance, net	459	499
North America Exploration and Production [Member]
Goodwill [Line Items]
Beginning balance, gross		347		343
Less: accumulated impairment		0		0
Goodwill [Roll Forward]
Beginning balance, net	347	343
Dispositions	(3)	4	[1]
Ending balance, net	344	347
International Exploration and Production [Member]
Goodwill [Line Items]
Beginning balance, gross		152		182
Less: accumulated impairment		0		0
Goodwill [Roll Forward]
Beginning balance, net	152	182
Dispositions	(37)	(30)
Ending balance, net	115	152
Oil Sands Mining Segment [Member]
Goodwill [Line Items]
Beginning balance, gross		1,412		1,412
Less: accumulated impairment		(1,412)		(1,412)
Goodwill [Roll Forward]
Beginning balance, net	0	0
Dispositions	0	0
Ending balance, net	$ 0	$ 0

[1] Goodwill related to our Alaska disposition was less than the estimate classified as held for sale in 2012.