Segment Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016		Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues from Third Parties		$ 705		$ 749
Income from Equity Method Investees		19		18
Total Revenues		724	[1]	767
DD&A		617		454
Asset Impairments	[2]	0		27
Gain on Commodity Derivative Instruments		(44)		(150)
Income (Loss) Before Income Taxes		(453)		(42)
Total Assets		23,413			$ 24,196
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties		489		487
Income from Equity Method Investees		16		11
Total Revenues		505		498
DD&A		530		357
Asset Impairments				3
Gain on Commodity Derivative Instruments		(37)		(105)
Income (Loss) Before Income Taxes		(292)		(1)
Total Assets		18,387			18,831
West Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties		90		138
Income from Equity Method Investees		3		7
Total Revenues		93		145
DD&A		55		77
Asset Impairments				0
Gain on Commodity Derivative Instruments		(7)		(45)
Income (Loss) Before Income Taxes		9		74
Total Assets		2,233			2,299
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties		126		120
Income from Equity Method Investees		0		0
Total Revenues		126		120
DD&A		20		15
Asset Impairments				24
Gain on Commodity Derivative Instruments		0		0
Income (Loss) Before Income Taxes		84		51
Total Assets		2,459			2,677
Other Int'l & Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties		0		4
Income from Equity Method Investees		0		0
Total Revenues		0		4
DD&A		12		5
Asset Impairments				0
Gain on Commodity Derivative Instruments		0		0
Income (Loss) Before Income Taxes		(254)		$ (166)
Total Assets		$ 334			$ 389

[1] No pro forma adjustments were made for the period as the acquisition is included in the Company's historical results.

[2] Impairments during 2015 were related to facility costs at South Raton (Deepwater Gulf of Mexico) and increases in expected field abandonment cost for the Noa and Pinnacles fields (Eastern Mediterranean).