Segment Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Operating_Segments		Dec. 31, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of Operating Segments	4
Revenues from Third Parties	$ 4,809	[1]	$ 4,037	[1]	$ 3,211	[1]
Income from Equity Method Investees	206		186		193
Revenues	5,015		4,223		3,404
DD&A	1,568		1,370		878
Asset Impairments	86		104		757
Gain on Divestitures	36		154		25
Income (Loss) from Continuing Operations Before Income Taxes	1,344		1,356		502
Equity Method Investments	437		367		329
Additions to Long-Lived Assets	4,534		3,525		4,358
Goodwill at End of Year	627		635		696
Total Assets at End of Year	19,598	[2]	17,509	[2]	16,105	[2]
Foreign Countries [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	1,800		1,700		1,100
Total Assets at End of Year	4,500		4,200	[2]	3,200
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	3,004	[1]	2,339	[1]	2,125	[1]
Income from Equity Method Investees	0		0		0
Revenues	3,004		2,339		2,125
DD&A	1,117		929		732
Asset Impairments	39		73		757
Gain on Divestitures			154		0
Income (Loss) from Continuing Operations Before Income Taxes	790		806		96
Equity Method Investments	184		121		72
Additions to Long-Lived Assets	3,475		2,046		3,007
Goodwill at End of Year			635		696
Total Assets at End of Year	13,094	[2]	11,199	[2]	11,201
West Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	1,252	[1]	1,343	[1]	592	[1]
Income from Equity Method Investees	206		186		193
Revenues	1,458		1,529		785
DD&A	261		255		69
Asset Impairments	0		0		0
Gain on Divestitures	0		0		0
Income (Loss) from Continuing Operations Before Income Taxes	936		1,074		561
Equity Method Investments	234		230		257
Additions to Long-Lived Assets	453		447		618
Goodwill at End of Year	0		0		0
Total Assets at End of Year	3,199	[2]	3,063	[2]	2,728	[2]
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	391	[1]	178	[1]	307	[1]
Income from Equity Method Investees	0		0		0
Revenues	391		178		307
DD&A	97		111		25
Asset Impairments	47		31		0
Gain on Divestitures	0		0		0
Income (Loss) from Continuing Operations Before Income Taxes	162		9		228
Equity Method Investments	0		0		0
Additions to Long-Lived Assets	420		869		687
Goodwill at End of Year	0		0		0
Total Assets at End of Year	2,753	[2]	2,572	[2]	1,751	[2]
Other International And Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	162	[1]	177	[1]	187	[1]
Income from Equity Method Investees	0		0		0
Revenues	162		177		187
DD&A	93		75		52
Asset Impairments	0		0		0
Gain on Divestitures	0		0		25
Income (Loss) from Continuing Operations Before Income Taxes	(544)		(533)		(383)
Equity Method Investments	19		16		0
Additions to Long-Lived Assets	186		163		46
Goodwill at End of Year	0		0		0
Total Assets at End of Year	$ 552	[2]	$ 675	[2]	$ 425	[2]

[1] Revenues from third parties for all foreign countries, in total, were $1.8 billion in 2013, $1.7 billion in 2012, and $1.1 billion in 2011.

[2] Long-lived assets located in all foreign countries, in total, were $4.5 billion, $4.2 billion, and $3.2 billion at December 31, 2013, 2012, and 2011, respectively.