Segments - Schedule of Adjusted EBITDA and Reconciling Items (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended					4 Months Ended	5 Months Ended	9 Months Ended
	Jun. 30, 2023	May 17, 2023	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2023	May 17, 2023	Sep. 30, 2024
Segment Reporting Information [Line Items]
Adjusted EBITDA			$ 245			$ 251		$ 344	$ 725	$ 663
Interest expense and other finance charges			(66)			(68)		(101)	(163)	(187)
Income tax benefit (expense)			(11)			16		(3)	(212)	(192)
Depreciation, amortization and accretion (Note 8)			(75)			(66)		(94)	(200)	(225)
Nuclear fuel amortization			(30)			(47)		(72)	(33)	(93)
Reorganization gain (loss), net			0			0		0	799	0
Unrealized (gain) loss on commodity derivative contracts			102			(84)		(43)	(63)	58
Nuclear decommissioning trust funds gain (loss), net			67			(24)		15	57	169
Stock-based compensation expense			(8)			(9)		(11)	0	(24)
Long-term incentive compensation expense			(3)			0		0	0	(19)
Gain (loss) on asset sales, net			0			0		0	50	885
Impairments			0			(2)		(2)	(381)	0
Operational and other restructuring activities			(40)			(4)		(30)	(17)	(61)
Development expenses			(1)			(5)		(7)	(10)	(1)
Non-cash inventory net realizable value, obsolescence, and other charges			(2)			2		(1)	(56)	(5)
Noncontrolling interest			3			14		22	14	21
Other items			2			(23)		(21)	(15)	13
Net Income (Loss)	$ 31	$ 419	168	$ 458	$ 319	(76)	$ 46	(45)	465	945
Corporate and Eliminations
Segment Reporting Information [Line Items]
Interest expense and other finance charges			(66)			(68)		(101)	(163)	(187)
Net Income (Loss)			(15)			(27)		(41)	(30)	(57)
PJM
Segment Reporting Information [Line Items]
Adjusted EBITDA			217			168		240	688	592
PJM | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA			217			168		240	688	592
Interest expense and other finance charges			0			0		0	0	0
Other
Segment Reporting Information [Line Items]
Adjusted EBITDA			28			83		104	37	71
Other | Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA			28			83		104	37	71
Interest expense and other finance charges			$ 0			$ 0		$ 0	$ 0	$ 0