Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues from Third Parties	$ 740	$ 1,327
Income from Equity Method Investees	18	52
Other	1	0
DD&A	454	425
Asset Impairments	27	97
Loss on Commodity Derivative Instruments	150	(75)
Total Revenues	759	1,379
Income (Loss) Before Income Taxes	(42)	277
Total Assets	23,261		22,553
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	478	842
Income from Equity Method Investees	11	0
Other	1
DD&A	357	308
Asset Impairments	3	5
Loss on Commodity Derivative Instruments	105	(76)
Total Revenues	490	842
Income (Loss) Before Income Taxes	(1)	183
Total Assets	16,998		16,400
West Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	138	323
Income from Equity Method Investees	7	52
Other	0
DD&A	77	76
Asset Impairments	0	0
Loss on Commodity Derivative Instruments	45	1
Total Revenues	145	375
Income (Loss) Before Income Taxes	74	261
Total Assets	2,732		2,763
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	120	112
Income from Equity Method Investees	0	0
Other	0
DD&A	15	14
Asset Impairments	24	0
Loss on Commodity Derivative Instruments	0	0
Total Revenues	120	112
Income (Loss) Before Income Taxes	51	77
Total Assets	2,840		2,806
Other Int'l & Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	4	50
Income from Equity Method Investees	0	0
Other	0
DD&A	5	27
Asset Impairments	0	92
Loss on Commodity Derivative Instruments	0	0
Total Revenues	4	50
Income (Loss) Before Income Taxes	(166)	(244)
Total Assets	$ 691		$ 584