Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Business Segment Information
Oil and gas production revenues	$ 4,355	$ 2,969	$ 8,233	$ 5,662
Operating Income	2,298	1,539	4,340	2,912
Other Income (Expense):
Other	(17)	3	30	(17)
General and administrative	(103)	(84)	(215)	(171)
Merger, acquisitions & transition	(6)	(8)	(11)	(8)
Financing costs, net	(41)	(56)	(86)	(115)
INCOME BEFORE INCOME TAXES	2,131	1,394	4,058	2,601
Total assets	46,529	30,432	46,529	30,432	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	1,560	962	2,937	1,954
Operating Income	738	452	1,368	963
Other Income (Expense):
Total assets	22,142	12,473	22,142	12,473
Canada [Member]
Business Segment Information
Oil and gas production revenues	433	240	835	493
Operating Income	104	71	182	166
Other Income (Expense):
Total assets	8,680	4,243	8,680	4,243
Egypt [Member]
Business Segment Information
Oil and gas production revenues	1,201	806	2,401	1,547
Operating Income	893	548	1,787	1,041
Other Income (Expense):
Total assets	6,677	5,910	6,677	5,910
Australia [Member]
Business Segment Information
Oil and gas production revenues	470	452	842	676
Operating Income	311	285	536	386
Other Income (Expense):
Total assets	4,272	3,737	4,272	3,737
U K North Sea [Member]
Business Segment Information
Oil and gas production revenues	572	421	1,002	812
Operating Income	257	165	462	313
Other Income (Expense):
Total assets	2,999	2,526	2,999	2,526
Argentina [Member]
Business Segment Information
Oil and gas production revenues	119	88	216	180
Operating Income	21	18	31	43
Other Income (Expense):
Total assets	1,686	1,488	1,686	1,488
Other International [Member]
Business Segment Information
Operating Income			(26)
Other Income (Expense):
Total assets	$ 73	$ 55	$ 73	$ 55