Retirement Plans (Net Periodic Benefit Cost) (Details) - 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
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension settlement costs					$ 50
Pension remeasurement gain					(91)
Successor [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension remeasurement gain	$ (91)				(91)
Successor [Member] | Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	14	$ 20		$ 33	55
Interest cost on projected benefit obligation	22	26		44	71
Expected return on plan assets	(46)	(49)		(80)	(145)
Net periodic (benefit) cost	(10)	(3)		(3)	(19)
Pension settlement costs	50				50
Pension remeasurement gain	(91)				(91)
Total pension benefit	(51)	(3)		(3)	(60)
Successor [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	4		7	10
Interest cost on projected benefit obligation	9	7		12	23
Amortization of prior service benefit	(4)	(2)		(3)	(10)
Remeasurement gains	(84)	54		67	(234)
Net periodic (benefit) cost	$ (76)	$ 63		$ 83	$ (211)
Predecessor [Member] | Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost			$ 32
Interest cost on projected benefit obligation			31
Expected return on plan assets			(61)
Amortization of unrecognized loss			24
Net periodic (benefit) cost			26
Total pension benefit			26
Predecessor [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost			7
Interest cost on projected benefit obligation			9
Amortization of prior service benefit			(10)
Amortization of unrecognized loss			5
Net periodic (benefit) cost			$ 11