Derivatives - Marketing Derivatives (Details)	3 Months Ended				12 Months Ended
	Mar. 31, 2021 $ / bbl	Mar. 31, 2021 $ / MillionCubicFeet	Mar. 31, 2021 MMBbls	Mar. 31, 2021 Bcf	Dec. 31, 2020 $ / bbl	Dec. 31, 2020 $ / MillionCubicFeet	Dec. 31, 2020 MMBbls	Dec. 31, 2020 Bcf
Marketing Derivatives | Not designated as hedging instruments
Outstanding commodity derivatives contracts not designated as hedging instruments
Weighted average sales price (dollars per barrel)	58.84	2.51			46.05	2.58
Crude oil | Short position
Outstanding commodity derivatives contracts not designated as hedging instruments
Outstanding net volumes on derivatives not designated as hedges (mmbls/bcf) | MMBbls			(28)				(31)
Natural gas | Short position
Outstanding commodity derivatives contracts not designated as hedging instruments
Outstanding net volumes on derivatives not designated as hedges (mmbls/bcf) | Bcf				(130)				(117)