Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	5 Months Ended	6 Months Ended
	Jun. 30, 2023	May 17, 2023	Jun. 30, 2024	May 17, 2023	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 50	$ 617	$ 570	$ 677	$ 958
Income tax benefit (expense)	$ (19)	$ (198)	$ (112)	$ (212)	$ (181)
Effective tax rate	38.00%	32.10%	19.60%	31.30%	18.90%
Federal income tax statutory tax rate	21.00%	21.00%	21.00%	21.00%	21.00%
Income tax benefit (expense) computed at the federal income tax statutory tax rate	$ (10)	$ (130)	$ (120)	$ (143)	$ (201)
Income tax increase (decrease) due to:
State income taxes, net of federal benefit	(2)	(32)	(17)	(34)	(29)
Change in valuation allowance	2	116	14	129	34
Production tax credits	0	0	9	0	18
Other permanent differences	(3)	(11)	6	(16)	12
Nuclear decommissioning trust taxes	(6)	(2)	(4)	(9)	(15)
Reorganization adjustments	0	(138)	0	(138)	0
Other	0	(1)	0	(1)	0
Income tax benefit (expense)	$ (19)	$ (198)	$ (112)	$ (212)	$ (181)