Comprehensive Income (Loss) (Tables)	12 Months Ended
Dec. 31, 2021
Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Net Of Tax	($ in millions) Pension Costs OPEB Costs Total Balance at December 31, 2018 (Predecessor) (1) $ (489) $ 26 $ (463) Other comprehensive income (loss) before reclassifications (201) 17 (184) Amounts reclassified from accumulated other comprehensive loss to net loss 89 (13) 76 Net current-period other comprehensive income (loss) (112) 4 (108) Impact of adoption of ASU 2018-02 (83) 4 (79) Balance at December 31, 2019 (Predecessor) (1) (684) 34 (650) Other comprehensive income (loss) before reclassifications (320) (76) (396) Amounts reclassified from accumulated other comprehensive loss to net loss 305 (14) 291 Net current-period other comprehensive income (loss) 15 (90) (105) Balance at December 31, 2020 (Predecessor) (1) $ (699) $ (56) $ (755) Other comprehensive income before reclassifications 270 74 344 Amounts reclassified from accumulated other comprehensive loss to net loss 19 (4) 15 Net current-period other comprehensive income 289 70 359 Cancellation of Predecessor equity 410 (14) 396 Balance at April 30, 2021 (Predecessor) (1) - - - Balance at April 30, 2021 (Successor) (1) $ - $ - $ - Other comprehensive income before reclassifications - 64 64 Amounts reclassified from accumulated other comprehensive income to net loss - (4) (4) Net current-period other comprehensive income - 60 60 Balance at December 31, 2021 (Successor) (1) $ - $ 60 $ 60 (1)Pension and OPEB amounts are net of deferred tax balances of $15 million, $234 million, $204 million, and $250 million as of December 31, 2021, 2020, 2019, and 2018, respectively.
Reclassification Out Of AOCI	Amount Reclassified from Accumulated Other Comprehensive Loss (1) Successor Predecessor For the eight For the four For the year months ended months ended For the year ended Affected line item in the Details about Accumulated Other December 31, April 30, December 31, December 31, statement where net Comprehensive Loss Components 2021 2021 2020 2019 income (loss) is presented Amortization of Pension Cost Items(2) Actuarial gains (losses) $ - $ (24) $ (99) $ (58) Loss on disposal - - (81) - Pension settlement costs - - (159) (57) Reclassifications, pretax - (24) (339) (115) Loss before income taxes Tax Impact - 5 34 26 Income tax benefit Reclassifications, net of tax $ - $ (19) $ (305) $ (89) Net loss Amortization of OPEB Cost Items(2) Prior-service credits (costs) $ 5 $ 10 $ 32 $ 11 Actuarial gains (losses) - (5) (6) 4 Loss on disposal - - (7) - Reclassifications, pretax 5 5 19 15 Income before income taxes Tax impact (1) (1) (5) (2) Income tax expense Reclassifications, net of tax $ 4 $ 4 $ 14 $ 13 Net gain (1)Amounts in parentheses indicate losses.(2)These accumulated other comprehensive loss components are included in the computation of net periodic pension and OPEB costs (see Note 20 - Retirement Plans for additional details).

Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2021

Comprehensive Income (Loss) [Abstract]

Accumulated Other Comprehensive Income (Loss), Net Of Tax

($ in millions) Pension Costs OPEB Costs Total Balance at December 31, 2018 (Predecessor) (1) $ (489) $ 26 $ (463) Other comprehensive income (loss) before reclassifications (201) 17 (184) Amounts reclassified from accumulated other comprehensive loss to net loss 89 (13) 76 Net current-period other comprehensive income (loss) (112) 4 (108) Impact of adoption of ASU 2018-02 (83) 4 (79) Balance at December 31, 2019 (Predecessor) (1) (684) 34 (650) Other comprehensive income (loss) before reclassifications (320) (76) (396) Amounts reclassified from accumulated other comprehensive loss to net loss 305 (14) 291 Net current-period other comprehensive income (loss) 15 (90) (105) Balance at December 31, 2020 (Predecessor) (1) $ (699) $ (56) $ (755) Other comprehensive income before reclassifications 270 74 344 Amounts reclassified from accumulated other comprehensive loss to net loss 19 (4) 15 Net current-period other comprehensive income 289 70 359 Cancellation of Predecessor equity 410 (14) 396 Balance at April 30, 2021 (Predecessor) (1) - - - Balance at April 30, 2021 (Successor) (1) $ - $ - $ - Other comprehensive income before reclassifications - 64 64 Amounts reclassified from accumulated other comprehensive income to net loss - (4) (4) Net current-period other comprehensive income - 60 60 Balance at December 31, 2021 (Successor) (1) $ - $ 60 $ 60 (1)Pension and OPEB amounts are net of deferred tax balances of $15 million, $234 million, $204 million, and $250 million as of December 31, 2021, 2020, 2019, and 2018, respectively.

Reclassification Out Of AOCI

Amount Reclassified from Accumulated Other Comprehensive Loss (1) Successor Predecessor For the eight For the four For the year months ended months ended For the year ended Affected line item in the Details about Accumulated Other December 31, April 30, December 31, December 31, statement where net Comprehensive Loss Components 2021 2021 2020 2019 income (loss) is presented Amortization of Pension Cost Items(2) Actuarial gains (losses) $ - $ (24) $ (99) $ (58) Loss on disposal - - (81) - Pension settlement costs - - (159) (57) Reclassifications, pretax - (24) (339) (115) Loss before income taxes Tax Impact - 5 34 26 Income tax benefit Reclassifications, net of tax $ - $ (19) $ (305) $ (89) Net loss Amortization of OPEB Cost Items(2) Prior-service credits (costs) $ 5 $ 10 $ 32 $ 11 Actuarial gains (losses) - (5) (6) 4 Loss on disposal - - (7) - Reclassifications, pretax 5 5 19 15 Income before income taxes Tax impact (1) (1) (5) (2) Income tax expense Reclassifications, net of tax $ 4 $ 4 $ 14 $ 13 Net gain (1)Amounts in parentheses indicate losses.(2)These accumulated other comprehensive loss components are included in the computation of net periodic pension and OPEB costs (see Note 20 - Retirement Plans for additional details).