Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting [Abstract]
Revenues	$ 807		$ 758		$ 1,735	$ 1,687
Purchased power and fuel	294		275		662	680
Generation, transmission and distribution	114		107		224	206
Administrative and other	96		97		192	192
Operating Expenses	210		204		416	398
Depreciation and amortization	139		122		279	243
Taxes other than income taxes	46		41		92	88
Costs and Expenses	689		642		1,449	1,409
Operating Income (Loss)	118		116		286	278
Interest Expense, Debt	60		56		120	111
Allowance for Funds Used During Construction, Capitalized Interest	(3)		(4)		(7)	(8)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	74		79		196	201
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	62	$ 100	$ 72	$ 109	162	181
Assets	$ 12,681				12,681		$ 12,544
Payments to Acquire Property, Plant, and Equipment					$ 596	$ 623