Suspended Exploratory Well Costs - Schedule Of Changes In Capitalized Exploratory Well Costs (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Capitalized Exploratory Well Costs [Abstract]
Capitalized Exploratory Well Costs, Beginning Balance	$ 7,709
Capitalized Exploratory Well Cost, Additions Pending Determination of Proved Reserves	2,264
Reclassification to Well, Facilities, and Equipment Based on Determination of Proved Reserves	0
Capitalized Exploratory Well Cost, Charged to Expense	0
Capitalized Exploratory Well Costs, Ending Balance	9,973
Capitalized Exploratory Well Costs that Have Been Capitalized for Period of One Year or Less	9,973
Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year	$ 0