Capitalized Exploratory Well Costs - Additional Information (Detail) $ in Millions	Mar. 31, 2018 USD ($)
Capitalized Exploratory Well Costs [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	$ 211
Northern Portion of Shenzi Field, Gulf of Mexico
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	55.00%
Project interest percentage	28.00%
Payara-1 Well on the Stabroek Block, Offshore Guyana
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	20.00%
Project interest percentage	30.00%
JDA, Gulf of Thailand
Capitalized Exploratory Well Costs [Line Items]
Capitalized well costs percentage	15.00%
Project interest percentage	50.00%