Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Capitalization of pension and OPEB expense	$ 6	$ 6
Successor [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
OPEB Remeasurement	54
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to plans	32
Increase in plan assets	184
Investment returns	183
Plan assets	2,471		$ 2,655
Benefit payments	$ 33