Capitalized Exploratory Well Costs (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Capitalized Exploratory Well Costs [Abstract]
Capitalized Exploratory Well Costs, Beginning of Period	$ 900		$ 696		$ 466
Additions to Capitalized Exploratory Well Costs Pending Determination of Proved Reserves	581		360		322
Reclassified to Proved Oil and Gas Properties Based on Determination of Proved Reserves (1)	(177)	[1]	(18)		(55)
Capitalized Exploratory Well Costs Charged to Expense	(3)	[2]	(114)	[2]	(37)	[2]
Other	0	[3]	(24)	[3]	0	[3]
Capitalized Exploratory Well Costs, End of Period	1,301		900		696
Capitalized Exploratory Well Costs Aging [Abstract]
Exploratory Well Costs Capitalized for a Period of One Year or Less	568		355		318
Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year	733		545		378
Capitalized Exploratory Well Costs,	$ 1,301		$ 900		$ 696
Number of Projects with Exploratory Well Costs That Have Been Capitalized for a Period Greater Than One Year Since Commencement of Drilling	13		14		13

[1] The 2013 amount relates primarily to Gunflint (deepwater Gulf of Mexico), for which we sanctioned a development plan.

[2] The 2012 amount primarily represents Deep Blue (deepwater Gulf of Mexico) exploratory well costs capitalized prior to December 31, 2012.

[3] The 2012 amount relates to Selkirk (North Sea) exploratory well costs capitalized prior to December 31, 2012. See Note 3. Property Transactions.