Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues from Third Parties	$ 1,327	$ 1,083
Income from Equity Method Investees	52	60
Total Revenues	1,379	1,143
DD&A	425	366
Asset Impairments	97	0
Income (Loss) from Continuing Operations Before Income Taxes	277	318
Total Assets	20,192		19,598
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	842	716
Income from Equity Method Investees	0	0
Total Revenues	842	716
DD&A	308	266
Asset Impairments	5	0
Income (Loss) from Continuing Operations Before Income Taxes	183	243
Total Assets	13,569		13,094
Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	323	273
Income from Equity Method Investees	52	60
Total Revenues	375	333
DD&A	76	54
Asset Impairments	0	0
Income (Loss) from Continuing Operations Before Income Taxes	261	231
Total Assets	3,193		3,199
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	112	51
Income from Equity Method Investees	0	0
Total Revenues	112	51
DD&A	14	28
Asset Impairments	0	0
Income (Loss) from Continuing Operations Before Income Taxes	77	15
Total Assets	2,822		2,753
Other Int'l & Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	50	43
Income from Equity Method Investees	0	0
Total Revenues	50	43
DD&A	27	18
Asset Impairments	92	0
Income (Loss) from Continuing Operations Before Income Taxes	(244)	(171)
Total Assets	$ 608		$ 552