Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Country	Mar. 31, 2011	Dec. 31, 2011
Business Segment Information
Oil and gas production revenues	$ 4,457	$ 3,878
Operating Income	1,655	2,042
Other Income (Expense):
Other	79	47
General and administrative	(128)	(112)
Merger, acquisitions & transition	(6)	(5)
Financing costs, net	(40)	(45)
INCOME BEFORE INCOME TAXES	1,560	1,927
Total assets	53,237	44,866	52,051
Business Segment Information (Textual) [Abstract]
Number of countries, in which the company has production	6
Income tax impact	521
United States [Member]
Business Segment Information
Oil and gas production revenues	1,550	1,377
Operating Income	672	629
Other Income (Expense):
Total assets	24,209	21,683
Canada [Member]
Business Segment Information
Oil and gas production revenues	353	402
Operating Income	(487)	78
Other Income (Expense):
Total assets	8,372	8,635
Egypt [Member]
Business Segment Information
Oil and gas production revenues	1,249	1,199
Operating Income	928	893
Other Income (Expense):
Total assets	6,870	6,266
Australia [Member]
Business Segment Information
Oil and gas production revenues	426	372
Operating Income	250	226
Other Income (Expense):
Total assets	5,334	4,016
North Sea [Member]
Business Segment Information
Oil and gas production revenues	742	430
Operating Income	264	206
Other Income (Expense):
Total assets	6,591	2,609
Argentina [Member]
Business Segment Information
Oil and gas production revenues	137	98
Operating Income	28	10
Other Income (Expense):
Total assets	1,773	1,598
Other International [Member]
Other Income (Expense):
Total assets	$ 88	$ 59