Comprehensive Income (Loss) (Reclassification Out Of AOCI) (Details) - Reclassification Out Of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2020
Pension [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax	$ (24)			$ (339)
Tax impact	5			34
Reclassifications, net of tax	(19)			(305)
Pension [Member] | Actuarial Losses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax	(24)			(99)
Pension [Member] | One-Time Loss On Disposal [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax				(81)
Pension [Member] | Pension Settlement Cost [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax				(159)
OPEB [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax	5	$ 5	$ 13	19
Tax impact	(1)	(1)	(2)	(5)
Reclassifications, net of tax	4	4	11	14
OPEB [Member] | Prior-Service Costs [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax	10	$ 5	$ 13	32
OPEB [Member] | Actuarial Losses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax	$ (5)			(6)
OPEB [Member] | One-Time Loss On Disposal [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax				$ (7)