Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2024	Dec. 31, 2023
Income Taxes [Line Items]
Regulatory assets			$ (40)	$ 102
Income tax expense (benefit)	$ 5	$ 14	3	26
Tax-related [Member]
Income Taxes [Line Items]
Regulatory assets	73
Income tax expense (benefit)	8	8
Forecast [Member]
Income Taxes [Line Items]
State income tax rate, percent					7.10%	8.40%
IPL [Member]
Income Taxes [Line Items]
Regulatory assets			(55)	(18)
Income tax expense (benefit)	(31)	(16)	(55)	(39)
IPL [Member] | Tax-related [Member]
Income Taxes [Line Items]
Regulatory assets	73
WPL [Member]
Income Taxes [Line Items]
Regulatory assets			16	120
Income tax expense (benefit)	$ 21	$ 16	$ 47	$ 50