Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - 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
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ 179	$ (92)	$ (42)	$ 677	$ 1,137
Income tax benefit (expense)	$ (11)	$ 16	$ (3)	$ (212)	$ (192)
Effective tax rate	6.10%	17.40%	(7.10%)	31.30%	16.90%
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	$ (38)	$ 19	$ 9	$ (143)	$ (239)
Income tax increase (decrease) due to:
State income taxes, net of federal benefit	(5)	3	1	(34)	(34)
Change in valuation allowance	29	(12)	(10)	129	63
Production tax credits	16	0	0	0	34
Other permanent differences	(3)	3	0	(16)	10
Nuclear decommissioning trust taxes	(10)	3	(3)	(9)	(26)
Reorganization adjustments	0	0	0	(138)	0
Other	0	0	0	(1)	0
Income tax benefit (expense)	$ (11)	$ 16	$ (3)	$ (212)	$ (192)