Comprehensive Income (Loss) (Reclassification Out Of AOCI) (Details) - Reclassification Out Of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Millions	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Apr. 30, 2021	Sep. 30, 2021	Sep. 30, 2022
Successor [Member] | OPEB [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax				$ 3	$ 10
Tax impact				(1)	(2)
Reclassifications, net of tax				2	8
Successor [Member] | OPEB [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax	$ 4	$ 2
Tax impact		(1)
Reclassifications, net of tax	$ 4	$ 1
Successor [Member] | OPEB [Member] | Prior-Service Costs [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax				$ 3	$ 10
Predecessor [Member] | Pension [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax			$ (24)
Tax impact			5
Reclassifications, net of tax			(19)
Predecessor [Member] | OPEB [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax			5
Tax impact			(1)
Reclassifications, net of tax			4
Predecessor [Member] | OPEB [Member] | Prior-Service Costs [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax			10
Predecessor [Member] | OPEB [Member] | Actuarial Losses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications, pretax			$ (5)