Fresh Start Accounting (Reconciliation Of Enterprise Value To Estimated Fair Value) (Details) - Successor [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	4 Months Ended
	Apr. 30, 2021	Dec. 31, 2021
Enterprise value	$ 12,500	$ 12,500
Plus: Cash and cash equivalents and restricted cash	940	2,178
Less: Fair value of debt and other liabilities	(7,267)
Less: Pension and other postretirement benefits	(1,774)
Less: Deferred tax liability	(291)	(387)
Fair value of Successor stockholders' equity	$ 4,108	$ 4,600
Shares issued upon emergence	244,401
Per share value	$ 17