Retirement Plans (Amounts Recognized As A Component Of AOCI) (Details) - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2021	Dec. 31, 2022
Pension [Member]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Accumulated other comprehensive (gain) loss at beginning of the period	$ 915
Net actuarial (gain) loss amortized during the period	(24)
Impact of fresh start accounting	(553)
Effect of settlements
Net actuarial loss occurring during the period	(338)
Net amount recognized in comprehensive (loss) for the period	(915)
Accumulated other comprehensive (gain) loss at end of the period
OPEB [Member]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Accumulated other comprehensive (gain) loss at beginning of the period	74		(75)
Net actuarial (gain) loss amortized during the period	(5)
Prior service credit amortized during the period	10	5	13
Impact of fresh start accounting	20
Prior service credit occurring during the period		(80)	(40)
Net actuarial loss occurring during the period	(99)
Net amount recognized in comprehensive (loss) for the period	(74)	(75)	(27)
Accumulated other comprehensive (gain) loss at end of the period		$ (75)	$ (102)