Restructuring Charges (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 7	$ 16	$ 11
Fayetteville Shale
Restructuring Cost and Reserve [Line Items]
Operating lease term				10 years
Fayetteville Shale | Office Consolidation and Reorganization
Restructuring Cost and Reserve [Line Items]
Office consolidation			2
Fayetteville Shale | Lease Termination
Restructuring Cost and Reserve [Line Items]
Office consolidation			3
Fayetteville Shale | Other Office Consolidation Expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1