Asset Impairments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	$ 0	$ 33	$ 43	$ 164
Deepwater Gulf of Mexico (US Properties) [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	0	2	11	56
Eastern Mediterranean [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	0	31	32	14
North Sea [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	$ 0	$ 0	$ 0	$ 94