Supplemental Information To Statements Of Cash Flows (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jan. 07, 2021	Dec. 31, 2020
Total Property And Equipment Net And Accounts Payable Member
Supplemental Cash Flow [Line Items]
Accrued capital expenditures	$ 200		$ 100
Accounts Payable Member | WPX
Supplemental Cash Flow [Line Items]
Accrued capital expenditures		$ 150