Accounts Receivable (Accounts Receivable) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Apr. 30, 2021	Dec. 31, 2020
Successor [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for credit losses	$ (18)
Accounts receivable, net	504
Successor [Member] | Retail And Wholesale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	447
Successor [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 75
Predecessor [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for credit losses			$ (130)
Accounts receivable, net			553
Predecessor [Member] | Retail And Wholesale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			608
Predecessor [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable			$ 75