Capitalized Exploratory Well Costs - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) km² Well	Sep. 30, 2015 USD ($)
Capitalized Exploratory Well Costs [Line Items]
Exploratory wells costs charged to expense	$ 234	$ 180
Exploratory dry hole costs which were incurred and expensed in the same reporting period	120
Capitalized exploratory well costs that have been capitalized for period greater than one year	$ 1,167
Stabroek Block, Offshore Guyana
Capitalized Exploratory Well Costs [Line Items]
Number of non-operated exploration wells | Well	2
Capitalized well costs percentage	10.00%
Participating interest rate on exploration well	30.00%
Exploration and drilling of well in square kilometers 3D seismic shoot | km²	17,000
Equus Project On License WA-390-P, Offshore Western Australia
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	70.00%
Participating interest rate on exploration well	100.00%
Offshore Ghana
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	20.00%
Percentage of ownership interest on license	50.00%