Segments - Segments and Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Operating revenues	$ 630	$ 489	$ 1,020	$ 998
Operation, maintenance and development expenses	192	164	338	318
Interest expense and other finance charges	62	62	136	121
Capital expenditures	37	14	101	80
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	115	95	324	375
Operating Segments \| PJM
Segment Reporting Information [Line Items]
Operating revenues	638	438	1,005	871
Operation, maintenance and development expenses	180	141	318	269
Interest expense and other finance charges	0	0	0	0
Other segment items	343	202	363	227
Adjusted EBITDA	115	95	324	375
Capital expenditures	33	14	95	66
Operating Segments \| Other
Segment Reporting Information [Line Items]
Operating revenues	(1)	58	41	208
Operation, maintenance and development expenses	12	23	20	49
Interest expense and other finance charges	0	0	0	0
Capital expenditures	4	0	5	14
Corporate and Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(7)	(7)	(26)	(81)
Interest expense and other finance charges	62	62	136	121
Capital expenditures	$ 0	$ 0	$ 1	$ 0

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