Supplemental Oil and Gas Disclosures (Unaudited) (Composition of Net Unevaluated Costs Excluded from Amortization) (Details) - USD ($) $ in Millions	12 Months Ended			180 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Capitalized Costs of Unproved Properties Excluded from Amortization, Period Cost [Abstract]
Property acquisition costs	$ 784	$ 85	$ 9	$ 1,079
Exploration and development costs	28	9	7	10
Capitalized interest	75	48	36	61
Net unevaluated costs excluded from amortization	887	142	$ 52	$ 1,150
Capitalized Costs of Unproved Properties Excluded from Amortization, Cumulative [Abstract]
Property acquisition costs	1,957
Exploration and development costs	54
Capitalized interest	220
Net unevaluated costs excluded from amortization, cumulative	$ 2,231	$ 1,472