Income Taxes (Components Of Net Deferred Income Tax Liability (Asset) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Successor [Member]
Deferred income tax liabilities:
Property, plant and equipment basis differences	$ 859
Intangibles	140
Deferred revenue/expense	(3)
Other, net	46
Gross deferred income tax liability	1,042
Deferred income tax assets:
Pension liability	212
Tax operating loss carryforward	185
Employee benefits	151
Accrued expenses	76
Lease obligations	75
Tax credit	4
Allowance for doubtful accounts	14
Other, net	30
Gross deferred income tax asset	747
Less: Valuation allowance	(92)
Net deferred income tax asset	655
Net deferred income tax liability	$ 387
Predecessor [Member]
Deferred income tax liabilities:
Property, plant and equipment basis differences		$ 1,873
Deferred revenue/expense		44
Other, net		56
Gross deferred income tax liability		1,973
Deferred income tax assets:
Pension liability		308
Intangibles		681
Tax operating loss carryforward		923
Employee benefits		207
Interest expense deduction limitation carryforward		44
Accrued expenses		75
Lease obligations		83
Tax credit		40
Allowance for doubtful accounts		35
Other, net		17
Gross deferred income tax asset		2,413
Less: Valuation allowance		(783)
Net deferred income tax asset		1,630
Net deferred income tax liability		$ 343