Exploratory Well Costs (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($) well
Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Balance at January 1	$ 29
Additions Pending the Determination of Proved Reserves	48
Reclassifications to Proved Properties	(4)
Costs Charged to Expense (1)	(12)	[1]
Balance at September 30	61
Capitalized Exploratory Well Costs that Have Been Capitalized for Period of One Year or Less	46
Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year	$ 15	[2]
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects | well	1

[1] Includes capitalized exploratory well costs charged to either dry hole costs or impairments.

[2] Consists of costs related to a project in Trinidad at September 30, 2021.