Suspended Exploratory Well Costs (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Capitalized Exploratory Well Costs [Abstract]
Suspended exploratory well costs	$ 1,200	$ 1,100
Property, Plant, and Equipment [Line Items]
Suspended exploratory well costs previously capitalized for a period greater than one year since the completion of drilling at December 31, 2015, charged to exploration expense	142
Shenandoah Well in the Gulf of Mexico [Member]
Property, Plant, and Equipment [Line Items]
Suspended exploratory well costs previously capitalized for a period greater than one year since the completion of drilling at December 31, 2015, charged to exploration expense	64
Orca-4 Well in Mozambique [Member]
Property, Plant, and Equipment [Line Items]
Suspended exploratory well costs previously capitalized for a period greater than one year since the completion of drilling at December 31, 2015, charged to exploration expense	38
Tubarão Tigre Discovery [Member]
Property, Plant, and Equipment [Line Items]
Suspended exploratory well costs previously capitalized for a period greater than one year since the completion of drilling at December 31, 2015, charged to exploration expense	33
Suspended exploratory well costs previously capitalized for less than one year at December 31, 2015, charged to expense	$ 21