Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	May 17, 2023	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 465	$ 143	$ 1,013	$ (1,293)
Other Comprehensive Income (Loss)
Available-for-sale securities unrealized gain (loss), net (Note 9)	6	2	(14)	(69)
Postretirement benefit actuarial (gain) loss, net (Note 15)	0	(38)	5	(15)
Postretirement benefit prior service (credits) costs, net (Note 15)	0	0	21	0
Income tax benefit (expense)	(2)	8	5	31
Gains (losses) arising during the period, net of tax	4	(28)	17	(53)
Available-for-sale securities unrealized (gain) loss, net (Note 9)	4	7	1	33
Qualifying derivatives unrealized (gain) loss, net	(1)	0	0	(2)
Postretirement benefit prior service (credits) costs, net (Note 15)	0	0	(1)	1
Postretirement benefit actuarial (gain) loss, net (Note 15)	2	0	0	27
Income tax benefit (expense)	(3)	(2)	(6)	(21)
Reclassifications from AOCI, net of tax	2	5	(6)	38
Other comprehensive income (loss)	6	(23)	11	(15)
Comprehensive Income (Loss)	471	120	1,024	(1,308)
Less: Comprehensive income (loss) attributable to noncontrolling interest	(14)	9	15	(4)
Comprehensive Income (Loss) Attributable to Stockholders (Successor) / Member (Predecessor)	$ 485	$ 111	$ 1,009	$ (1,304)