Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues from Third Parties	$ 722	$ 1,338	$ 1,462	$ 2,665
Income (Loss) from Equity Method Investees	6	45	24	97
Other	2	0	4	0
DD&A	451	413	905	837
Gain on Divestitures	(1)	(44)	0	(42)
Asset Impairments	15	34	43	131
(Gain) Loss on Commodity Derivative Instruments	87	236	(63)	311
Total Revenues	730	1,383	1,490	2,762
Income (Loss) Before Income Taxes	(293)	233	(334)	510
Total Assets	22,685		22,685		$ 22,553
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	441	842	919	1,684
Income (Loss) from Equity Method Investees	8	0	19	0
Other	2		4
DD&A	344	311	701	619
Gain on Divestitures	(1)	(8)	0	(6)
Asset Impairments	8	18	11	23
(Gain) Loss on Commodity Derivative Instruments	62	170	(43)	246
Total Revenues	451	842	942	1,684
Income (Loss) Before Income Taxes	(163)	199	(164)	382
Total Assets	16,755		16,755		16,400
West Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	174	339	312	662
Income (Loss) from Equity Method Investees	(2)	45	5	97
Other	0		0
DD&A	79	72	156	148
Gain on Divestitures	0	0	0	0
Asset Impairments	0	0	0	0
(Gain) Loss on Commodity Derivative Instruments	25	66	(20)	65
Total Revenues	172	384	317	759
Income (Loss) Before Income Taxes	23	204	97	465
Total Assets	2,628		2,628		2,763
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	106	113	226	225
Income (Loss) from Equity Method Investees	0	0	0	0
Other	0		0
DD&A	15	15	30	29
Gain on Divestitures	0	0	0	0
Asset Impairments	7	14	32	14
(Gain) Loss on Commodity Derivative Instruments	0	0	0	0
Total Revenues	106	113	226	225
Income (Loss) Before Income Taxes	69	44	120	121
Total Assets	2,802		2,802		2,806
Other Int'l & Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	1	44	5	94
Income (Loss) from Equity Method Investees	0	0	0	0
Other	0		0
DD&A	13	15	18	41
Gain on Divestitures	0	(36)	0	(36)
Asset Impairments	0	2	0	94
(Gain) Loss on Commodity Derivative Instruments	0	0	0	0
Total Revenues	1	44	5	94
Income (Loss) Before Income Taxes	(222)	$ (214)	(387)	$ (458)
Total Assets	$ 500		$ 500		$ 584