Property, Plant and Equipment (Equity and Debt AFUDC) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	$ 25	$ 55	$ 93
Equity [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	18	39	66
Debt [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	7	16	27
IPL [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	9	24	50
IPL [Member] | Equity [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	7	17	35
IPL [Member] | Debt [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	2	7	15
WPL [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	16	31	43
WPL [Member] | Equity [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	11	22	31
WPL [Member] | Debt [Member]
Property, Plant and Equipment [Line Items]
Allowance for funds used during construction	$ 5	$ 9	$ 12