Exploratory Well Costs (Details) $ in Millions	6 Months Ended
	Jun. 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	14
Reclassifications to Proved Properties	(3)
Costs Charged to Expense (1)	(12)	[1]
Balance at June 30	28
Capitalized Exploratory Well Costs that Have Been Capitalized for Period of One Year or Less	13
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 June 30, 2021.