Supplementary Oil and Gas Disclosure (Unaudited) - Other Costs Incurred (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Ceiling test impairment	$ 0	$ 0	$ 1,488,000,000
Capitalized costs of oil and gas properties not included in total costs incurred	2,206,000,000	23,000,000	2,094,000,000
Domestic [Member]
Ceiling test impairment	0	0	1,488,000,000
Property sales excluded from cost incurred	635,000,000	23,000,000	606,000,000
Malaysia [Member]
Property sales excluded from cost incurred	$ 1,571,000,000	$ 0	$ 0