Suspended Exploratory Well Costs - Aging by Geographic Area of Exploratory Well Costs Capitalized for a Period Greater Than One Year (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) Project	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Capitalized Exploratory Well Costs [Line Items]
Projects with exploratory well costs capitalized for a period greater than one year after completion of drilling | Project	29
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 672	$ 1,129	$ 1,396
Aging of Capitalized Exploratory Well Costs, Period One [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 230
Aging of capitalized exploratory well costs, period start date	Jan. 01, 2014
Aging of capitalized exploratory well costs, period end date	Dec. 31, 2014
Aging of Capitalized Exploratory Well Costs, Period Two [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 94
Aging of capitalized exploratory well costs, period start date	Jan. 01, 2013
Aging of capitalized exploratory well costs, period end date	Dec. 31, 2013
Aging of Capitalized Exploratory Well Costs, Period Three [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 348
Aging of capitalized exploratory well costs, period end date	Dec. 31, 2012
United States Onshore [Member]
Capitalized Exploratory Well Costs [Line Items]
Projects with exploratory well costs capitalized for a period greater than one year after completion of drilling | Project	18
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 55
United States Onshore [Member] | Aging of Capitalized Exploratory Well Costs, Period One [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	34
United States Onshore [Member] | Aging of Capitalized Exploratory Well Costs, Period Two [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	11
United States Onshore [Member] | Aging of Capitalized Exploratory Well Costs, Period Three [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 10
United States Offshore [Member]
Capitalized Exploratory Well Costs [Line Items]
Projects with exploratory well costs capitalized for a period greater than one year after completion of drilling | Project	4
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 314
United States Offshore [Member] | Aging of Capitalized Exploratory Well Costs, Period One [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	77
United States Offshore [Member] | Aging of Capitalized Exploratory Well Costs, Period Two [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	80
United States Offshore [Member] | Aging of Capitalized Exploratory Well Costs, Period Three [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 157
International [Member]
Capitalized Exploratory Well Costs [Line Items]
Projects with exploratory well costs capitalized for a period greater than one year after completion of drilling | Project	7
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 303
International [Member] | Aging of Capitalized Exploratory Well Costs, Period One [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	119
International [Member] | Aging of Capitalized Exploratory Well Costs, Period Two [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	3
International [Member] | Aging of Capitalized Exploratory Well Costs, Period Three [Member]
Capitalized Exploratory Well Costs [Line Items]
Suspended exploratory well costs capitalized for a period greater than one year after completion of drilling	$ 181