Capitalized Exploratory Well Costs - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) km²	Jun. 30, 2015 USD ($)
Capitalized Exploratory Well Costs [Line Items]
Exploratory wells costs charged to expense	$ 218	$ 176
Exploratory dry hole costs which were incurred and expensed in the same reporting period	104
Capitalized exploratory well costs that have been capitalized for period greater than one year	$ 1,150
Equus Project On License WA-390-P, Offshore Western Australia
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	70.00%
Offshore Ghana
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	20.00%
Stabroek Block, Offshore Guyana
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	10.00%
Exploration and drilling of well in square kilometers 3D seismic shoot | km²	17,000