Asset Impairments (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2015	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	$ 5	$ 31	$ 533	$ 500	$ 86
Onshore US
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments			0	42	39
Deepwater Gulf of Mexico
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments			158	350	0
Equatorial Guinea
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments			339	0	0
Eastern Mediterranean
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments			36	14	47
North Sea
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments			$ 0	$ 94	$ 0