Goodwill and Identifiable Intangible Assets and Liabilities - Schedule of Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 2,807
Measurement period adjustment recorded in connection with the Energy Harbor Merger	3
Balance at end of period	2,810
Energy Harbor
Goodwill [Roll Forward]
Balance at beginning of period	224
Measurement period adjustment recorded in connection with the Energy Harbor Merger	(224)
Balance at end of period	0
Retail Reporting Unit
Goodwill [Roll Forward]
Balance at beginning of period	2,461
Measurement period adjustment recorded in connection with the Energy Harbor Merger	227
Balance at end of period	2,688
Goodwill, expected tax deductible amount	$ 1,944
Business acquisition, goodwill, expected tax deductible term	15 years
Texas Generation Reporting Unit
Goodwill [Roll Forward]
Balance at beginning of period	$ 122
Measurement period adjustment recorded in connection with the Energy Harbor Merger	0
Balance at end of period	$ 122