Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues from Third Parties	$ 1,228	$ 1,341	$ 3,893	$ 3,537
Income from Equity Method Investees	41	53	138	150
Total Revenues	1,269	1,394	4,031	3,687
DD&A	460	412	1,297	1,146
Gain on Divestitures	(30)	0	(72)	(12)
Asset Impairments	33	63	164	63
Income (Loss) from Continuing Operations Before Income Taxes	576	311	1,085	1,115
Total Assets	21,186		21,186		19,598
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	819	810	2,503	2,209
Income from Equity Method Investees	0	0	0	0
Total Revenues	819	810	2,503	2,209
DD&A	351	295	970	819
Gain on Divestitures	(30)	0	(36)	(12)
Asset Impairments	33	16	56	16
Income (Loss) from Continuing Operations Before Income Taxes	457	183	838	746
Total Assets	15,069		15,069		13,094
Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	269	372	931	935
Income from Equity Method Investees	41	53	138	150
Total Revenues	310	425	1,069	1,085
DD&A	70	72	218	189
Gain on Divestitures	0	0	0	0
Asset Impairments	0	0	0	0
Income (Loss) from Continuing Operations Before Income Taxes	321	223	786	722
Total Assets	2,930		2,930		3,199
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	138	122	363	274
Income from Equity Method Investees	0	0	0	0
Total Revenues	138	122	363	274
DD&A	17	26	46	81
Gain on Divestitures	0	0	0	0
Asset Impairments	0	47	14	47
Income (Loss) from Continuing Operations Before Income Taxes	90	34	211	93
Total Assets	2,855		2,855		2,753
Other Int'l & Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	2	37	96	119
Income from Equity Method Investees	0	0	0	0
Total Revenues	2	37	96	119
DD&A	22	19	63	57
Gain on Divestitures	0	0	(36)	0
Asset Impairments	0	0	94	0
Income (Loss) from Continuing Operations Before Income Taxes	(292)	(129)	(750)	(446)
Total Assets	$ 332		$ 332		$ 552