Properties and Equipment - Additional Information (Detail) (USD $) In Millions	3 Months Ended		9 Months Ended			9 Months Ended	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Sep. 30, 2011 Greater than one year [Member]	Sep. 30, 2011 Oil and Gas Exploration and Production Operating Segment [Member]	Jun. 30, 2011 Oil and Gas Exploration and Production Operating Segment [Member]	Jun. 30, 2010 Oil and Gas Exploration and Production Operating Segment [Member]	Sep. 30, 2010 Oil and Gas Exploration and Production Operating Segment [Member]	Sep. 30, 2011 Other Midstream Operating Segment [Member]
Property, Plant, and Equipment [Abstract]
Capitalized suspended well costs	$ 1,200		$ 1,200		$ 935
Capitalized suspended well costs reclassified to proved properties			116
Impairment expense	183	20	287	147
Property, Plant, and Equipment [Line Items]
Exploratory well costs previously capitalized as suspended well costs for greater than one year, charged to dry hole expense						32
Impairment of oil and gas properties							93	100	114	114
Impairments related to investment in Venezuelan assets							87
After-tax net investment in the Venezuelan assets							38
Losses on assets held for sale							268				31
Net properties and equipment associated with assets held for sale	273		273
Goodwill and other intangible assets associated with assets held for sale	42		42
Other long-term liabilities associated with assets held for sale	$ 6		$ 6