Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011 Country bbl	Sep. 30, 2010	Sep. 30, 2011 bbl Counterparty Country	Sep. 30, 2010	Dec. 31, 2010
Business Segment Information
Oil and gas production revenues	$ 4,282	$ 3,047	$ 12,515	$ 8,709
Operating Income	2,201	1,527	6,541	4,439
Other Income (Expense):
Other	46	(34)	76	(51)
General and administrative	(112)	(89)	(327)	(260)
Merger, acquisitions & transition	(4)	(8)	(15)	(16)
Financing costs, net	(37)	(59)	(123)	(174)
INCOME BEFORE INCOME TAXES	2,094	1,337	6,152	3,938
Total assets	47,482	36,928	47,482	36,928	43,425
Business Segment Information (Textuals) [Abstract]
Number of countries, in which the company has production	6		6
United States [Member]
Business Segment Information
Oil and gas production revenues	1,548	1,061	4,485	3,015
Operating Income	718	440	2,086	1,403
Other Income (Expense):
Total assets	23,039	15,968	23,039	15,968
Canada [Member]
Business Segment Information
Oil and gas production revenues	388	231	1,223	723
Operating Income	81	63	264	229
Other Income (Expense):
Total assets	8,443	7,722	8,443	7,722
Egypt [Member]
Business Segment Information
Oil and gas production revenues	1,214	822	3,615	2,369
Operating Income	893	561	2,679	1,601
Other Income (Expense):
Total assets	6,574	5,585	6,574	5,585
Australia [Member]
Business Segment Information
Oil and gas production revenues	461	431	1,303	1,108
Operating Income	288	267	823	653
Other Income (Expense):
Total assets	4,446	3,736	4,446	3,736
U K North Sea [Member]
Business Segment Information
Oil and gas production revenues	547	410	1,549	1,222
Operating Income	222	186	685	500
Other Income (Expense):
Total assets	3,166	2,329	3,166	2,329
Argentina [Member]
Business Segment Information
Oil and gas production revenues	124	92	340	272
Operating Income	19	10	50	53
Other Income (Expense):
Total assets	1,732	1,529	1,732	1,529
Other International [Member]
Business Segment Information
Operating Income	(20)		(46)
Other Income (Expense):
Total assets	$ 82	$ 59	$ 82	$ 59

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