Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues from Third Parties	$ 1,338	$ 1,112	$ 2,665	$ 2,196
Income from Equity Method Investees	45	37	97	96
Total Revenues	1,383	1,149	2,762	2,292
DD&A	413	368	837	734
(Gain) Loss on Divestitures	(44)	4	(42)	(12)
Asset Impairments	34	0	131	0
Income (Loss) from Continuing Operations Before Income Taxes	233	486	510	804
Total Assets	20,575		20,575		19,598
United States [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	842	683	1,684	1,399
Income from Equity Method Investees	0	0	0	0
Total Revenues	842	683	1,684	1,399
DD&A	311	258	619	524
(Gain) Loss on Divestitures	(8)	0	(6)	(12)
Asset Impairments	18	0	23	0
Income (Loss) from Continuing Operations Before Income Taxes	199	320	382	563
Total Assets	14,175		14,175		13,094
Africa [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	339	290	662	563
Income from Equity Method Investees	45	37	97	96
Total Revenues	384	327	759	659
DD&A	72	63	148	117
(Gain) Loss on Divestitures	0	4	0	0
Asset Impairments	0	0	0	0
Income (Loss) from Continuing Operations Before Income Taxes	204	268	465	499
Total Assets	3,152		3,152		3,199
Eastern Mediterranean [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	113	101	225	152
Income from Equity Method Investees	0	0	0	0
Total Revenues	113	101	225	152
DD&A	15	27	29	55
(Gain) Loss on Divestitures	0	0	0	0
Asset Impairments	14	0	14	0
Income (Loss) from Continuing Operations Before Income Taxes	44	44	121	59
Total Assets	2,762		2,762		2,753
Other Int'l & Corporate [Member]
Segment Reporting Information [Line Items]
Revenues from Third Parties	44	38	94	82
Income from Equity Method Investees	0	0	0	0
Total Revenues	44	38	94	82
DD&A	15	20	41	38
(Gain) Loss on Divestitures	(36)	0	(36)	0
Asset Impairments	2	0	94	0
Income (Loss) from Continuing Operations Before Income Taxes	(214)	(146)	(458)	(317)
Total Assets	$ 486		$ 486		$ 552