Segment Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 Operating_Segments		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Revenue from Third Parties	$ 4,037,000,000	[1]	$ 3,211,000,000	[1]	$ 2,615,000,000	[1]
Reclassification from AOCL					(20,000,000)	[2]
Income from Equity Method Investees	186,000,000		193,000,000		118,000,000
Total Revenues	4,223,000,000		3,404,000,000		2,713,000,000
DD&A	1,370,000,000		878,000,000		819,000,000
Asset Impairments	104,000,000		757,000,000		144,000,000
Gain on Divestitures	(154,000,000)		(25,000,000)		(113,000,000)
Gain on Commodity Derivative Instruments	(75,000,000)		(42,000,000)		(157,000,000)
Income (Loss) from Continuing Operations Before Income Taxes	1,356,000,000		502,000,000		848,000,000
Equity Method Investments	367,000,000		329,000,000		285,000,000
Additions to Long-Lived Assets	3,525,000,000		4,358,000,000		2,725,000,000
Goodwill at End of Year	635,000,000		696,000,000		696,000,000
Total Assets at End of Year	17,509,000,000	[3]	16,105,000,000	[3]	12,846,000,000	[3]
Number of Operating Segments	4
Revenues from third parties for all foreign countries	1,700,000,000		1,100,000,000		722,000,000
Long-lived Assets in Foreign Countries	4,200,000,000		3,200,000,000		2,000,000,000
United States [Member]
Segment Reporting Information [Line Items]
Revenue from Third Parties	2,339,000,000		2,125,000,000		1,893,000,000
Reclassification from AOCL					(20,000,000)	[2]
Income from Equity Method Investees	0		0		0
Total Revenues	2,339,000,000		2,125,000,000		1,873,000,000
DD&A	929,000,000		732,000,000		719,000,000
Asset Impairments	73,000,000		757,000,000		119,000,000
Gain on Divestitures	(154,000,000)		0		(113,000,000)
Gain on Commodity Derivative Instruments	(76,000,000)		(74,000,000)		(168,000,000)
Income (Loss) from Continuing Operations Before Income Taxes	806,000,000		96,000,000		713,000,000
Equity Method Investments	121,000,000		72,000,000		0
Additions to Long-Lived Assets	2,046,000,000		3,007,000,000		1,796,000,000
Goodwill at End of Year	635,000,000		696,000,000		696,000,000
Total Assets at End of Year	11,199,000,000	[2]	11,201,000,000	[2]	9,091,000,000	[2]
West Africa [Member]
Segment Reporting Information [Line Items]
Revenue from Third Parties	1,343,000,000	[1]	592,000,000	[1]	349,000,000	[1]
Reclassification from AOCL					0
Income from Equity Method Investees	186,000,000		193,000,000		118,000,000
Total Revenues	1,529,000,000		785,000,000		467,000,000
DD&A	255,000,000		69,000,000		39,000,000
Asset Impairments	0		0		0
Gain on Divestitures	0		0		0
Gain on Commodity Derivative Instruments	1,000,000		32,000,000		11,000,000
Income (Loss) from Continuing Operations Before Income Taxes	1,074,000,000		561,000,000		355,000,000
Equity Method Investments	230,000,000		257,000,000		285,000,000
Additions to Long-Lived Assets	447,000,000		618,000,000		612,000,000
Goodwill at End of Year	0		0		0
Total Assets at End of Year	3,063,000,000	[3]	2,728,000,000	[3]	2,270,000,000	[3]
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenue from Third Parties	178,000,000	[1]	307,000,000	[1]	191,000,000	[1]
Reclassification from AOCL					0
Income from Equity Method Investees	0		0		0
Total Revenues	178,000,000		307,000,000		191,000,000
DD&A	111,000,000		25,000,000		22,000,000
Asset Impairments	31,000,000		0		25,000,000
Gain on Divestitures	0		0		0
Gain on Commodity Derivative Instruments	0		0		0
Income (Loss) from Continuing Operations Before Income Taxes	9,000,000		228,000,000		119,000,000
Equity Method Investments	0		0		0
Additions to Long-Lived Assets	869,000,000		687,000,000		270,000,000
Goodwill at End of Year	0		0		0
Total Assets at End of Year	2,572,000,000	[3]	1,751,000,000	[3]	919,000,000	[3]
Other International And Corporate [Member]
Segment Reporting Information [Line Items]
Revenue from Third Parties	177,000,000	[1]	187,000,000	[1]	182,000,000	[1]
Reclassification from AOCL					0
Income from Equity Method Investees	0		0		0
Total Revenues	177,000,000		187,000,000		182,000,000
DD&A	75,000,000		52,000,000		39,000,000
Asset Impairments	0		0		0
Gain on Divestitures	0		(25,000,000)		0
Gain on Commodity Derivative Instruments	0		0		0
Income (Loss) from Continuing Operations Before Income Taxes	(533,000,000)		(383,000,000)		(339,000,000)
Equity Method Investments	16,000,000		0		0
Additions to Long-Lived Assets	163,000,000		46,000,000		47,000,000
Goodwill at End of Year	0		0		0
Total Assets at End of Year	$ 675,000,000	[3]	$ 425,000,000	[3]	$ 566,000,000	[3]

[1] Revenues from third parties for all foreign countries, in total, were $1.7 billion in 2012, $1.1 billion in 2011, and $722 million in 2010.

[2] Revenues for the year ended December 31, 2010 include decreases resulting from hedging activities. The decreases resulted from hedge gains and losses that were deferred in AOCL, as a result of previous cash flow hedge accounting, and subsequently reclassified to revenues. All hedge gains and losses had been reclassified to revenues by December 31, 2010.

[3] Long-lived assets located in all foreign countries, in total, were $4.2 billion, $3.2 billion, and $2.0 billion at December 31, 2012, 2011, and 2010 respectively.