Property, Plant and Equipment (Narrative) (Details)	9 Months Ended
	Sep. 30, 2024 USD ($) lease_renewal_period_option MW
IPL [Member]
Property, Plant and Equipment [Line Items]
Electric capacity of solar project | MW	400
Construction project cost target, exceedance	$ 1,837.5
Construction project cost target, original	$ 1,650
Solar project cost return on equity, percentage	10.25%
WPL [Member]
Property, Plant and Equipment [Line Items]
Electric capacity of solar project | MW	1,100
Construction project cost target, exceedance	$ 195,000,000
WPL [Member] | Sheboygan Falls Energy Facility
Property, Plant and Equipment [Line Items]
Financing lease, lease renewal periods remaining | lease_renewal_period_option	0
WPL [Member] | West Riverside Energy Center [Member]
Property, Plant and Equipment [Line Items]
Ownership interest, percent	56.60%
Electric Generation | WPL [Member] | Edgewater Unit 5
Property, Plant and Equipment [Line Items]
Net book value, Edgewater Unit 5	$ 493,000,000
Utility electric generation plant in service, Edgewater Unit 5	$ 794,000,000