Property, Plant and Equipment (Equity and Debt AFUDC) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	$ 100	$ 60	$ 25
Equity [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	74	44	18
Debt [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	26	16	7
IPL [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	21	11	9
IPL [Member] | Equity [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	15	8	7
IPL [Member] | Debt [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	6	3	2
WPL [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	79	49	16
WPL [Member] | Equity [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	59	36	11
WPL [Member] | Debt [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	$ 20	$ 13	$ 5