Retirement Plans (Net Periodic Benefit Cost) (Details) - 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]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 32	$ 53	$ 69	$ 95
Interest cost on projected benefit obligation	31	69	106	108
Expected return on plan assets	(61)	(127)	(181)	(171)
(Gain) / Loss recognized		6	(218)
Amortization of unrecognized loss	24			99
Net periodic benefit cost / (income)	26	1	(224)	131
Pension settlement costs			55	159
Gain on disposal, net				(38)
Total pension benefit cost / (income)	26	1	(169)	252
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	11	13	20
Interest cost on projected benefit obligation	9	18	31	33
(Gain) / Loss recognized		37	(248)
Amortization of prior service benefit	(10)	(5)	(13)	(32)
Amortization of unrecognized loss	5			6
Net periodic benefit cost / (income)	11	61	(217)	27
Gain on disposal, net				(24)
Total pension benefit cost / (income)	$ 11	$ 61	$ (217)	$ 3