Property, Plant and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2008
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Total capitalized exploratory well costs	$ 556,412,000	$ 497,765,000		$ 369,862,000		$ 310,118,000
Exploratory well costs capitalized more than one year	486,655,000
Impairment of long-lived assets	368,600,000	0	[1]	5,240,000	[1]
Malaysia
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Exploratory well costs capitalized more than one year	306,475,000
United States
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Exploratory well costs capitalized more than one year	138,634,000
Republic of the Congo
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Exploratory well costs capitalized more than one year	29,188,000
Canada
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Exploratory well costs capitalized more than one year	$ 12,358,000

[1] Reclassified to conform to current presentation.