Revenue - Summary of Disaggregation of Operating Revenues (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
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 177	$ 158	$ 346	$ 478	$ 762
Realized and unrealized gain (loss) on derivative instruments	124	(21)	100	732	157
Nuclear PTC and other revenue	0	0	43	0	79
Operating revenues	301	137	489	1,210	998
Amount of PTC revenue utilized as a credit against Federal Income Taxes payable					51
Capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26	42	46	108	91
Operating revenues	26	42	46	108	91
Electricity sales and ancillary services, ISO/RTO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	130	85	249	281	514
Physical electricity sales, bilateral contracts, other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	13	22	62	86
Other revenue from customers
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 15	$ 18	$ 29	$ 27	$ 71