Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Statutory federal income tax rate		21.00%	21.00%	35.00%
Income tax expense (benefits) Federal Tax Reform			$ (5.6)	$ (18.1)
Overall income tax rate		10.80%	8.40%	12.50%
IPL [Member]
Income Tax [Line Items]
Statutory federal income tax rate		21.00%	21.00%	35.00%
Income tax expense (benefits) Federal Tax Reform			$ (1.1)	$ 3.8
Overall income tax rate		7.60%	(1.20%)	(5.00%)
WPL [Member]
Income Tax [Line Items]
Statutory federal income tax rate		21.00%	21.00%	35.00%
Income tax expense (benefits) Federal Tax Reform			$ (5.5)	$ (14.5)
Overall income tax rate		17.50%	14.80%	24.90%
State [Member]
Income Tax [Line Items]
Overall income tax rate		12.00%
State [Member] | Forecast [Member]
Income Tax [Line Items]
Overall income tax rate	9.80%
State [Member] | IPL [Member]
Income Tax [Line Items]
Overall income tax rate		12.00%
State [Member] | IPL [Member] | Forecast [Member]
Income Tax [Line Items]
Overall income tax rate	9.80%
State [Member] | WPL [Member]
Income Tax [Line Items]
Overall income tax rate		12.00%
State [Member] | WPL [Member] | Forecast [Member]
Income Tax [Line Items]
Overall income tax rate	9.80%