Capitalized Exploratory Well Costs and Undeveloped Leasehold Costs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling
Impairment		$ 1,488
Delaware Basin
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling
Capitalized undeveloped leasehold cost		530
Other US Onshore Properties
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling
Capitalized undeveloped leasehold cost		80
Other Int'l
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling
Capitalized undeveloped leasehold cost		$ 54
Delaware Basin And Eagle Ford Shale
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling
Impairment	$ 1,500
Gabon
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling
Impairment	$ 3