Property, Plant and Equipment (Narrative) (Details) - WPL [Member] $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($) lease_renewal_period_option MW
Property, Plant and Equipment [Line Items]
Electric capacity of solar project | MW	1,100
Construction project cost target exceedance	$ 195
Sheboygan Falls Energy Facility
Property, Plant and Equipment [Line Items]
Financing lease, lease renewal periods remaining | lease_renewal_period_option	0
West Riverside Energy Center [Member]
Property, Plant and Equipment [Line Items]
Ownership interest, percent	56.60%
Electric Generation | Edgewater Unit 5
Property, Plant and Equipment [Line Items]
Net book value, Edgewater Unit 5	$ 496
Utility electric generation plant in service, Edgewater Unit 5	$ 806