Asset Impairments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	$ 27	$ 97
Deepwater Gulf of Mexico (US Properties) [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	3	0
Eastern Mediterranean [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	24	0
North Sea [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	0	92
Non-Core US Property [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset Impairments	$ 0	$ 5