Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2023	May 17, 2023	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 168	$ (76)	$ (45)	$ 465	$ 945
Other Comprehensive Income (Loss)
Available-for-sale securities unrealized gain (loss), net	17	(20)	(26)	6	5
Postretirement benefit prior service (credits) costs, net	21	0	0	0	21
Income tax benefit (expense)	(7)	7	9	(2)	(2)
Gains (losses) arising during the period, net of tax	31	(13)	(17)	4	24
Available-for-sale securities unrealized (gain) loss, net	(2)	6	7	4	(1)
Qualifying derivatives unrealized (gain) loss, net	0	0	0	(1)	0
Postretirement benefit actuarial (gain) loss, net	0	0	0	2	0
Income tax benefit (expense)	(5)	(2)	(2)	(3)	(5)
Reclassifications from AOCI, net of tax	(7)	4	5	2	(6)
Other comprehensive income (loss)	24	(9)	(12)	6	18
Comprehensive Income (Loss)	192	(85)	(57)	471	963
Less: Comprehensive income (loss) attributable to noncontrolling interest	0	1	3	(14)	29
Comprehensive Income (Loss) Attributable to Stockholders (Successor) / Member (Predecessor)	$ 192	$ (86)	$ (60)	$ 485	$ 934