Rate Matters (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fuel Rules [Abstract]
Deferred fuel rules monitored costs				$ (3.3)		$ 1.5
PSCW [Member] | MGE [Member]
Rate Proceedings [Abstract]
Authorized return on equity, percentage				9.80%	9.80%	9.80%
Approved equity capital structure, percentage				55.80%	56.10%	56.60%
Fuel Rules [Abstract]
Fuel rules, bandwidth				1.00%	2.00%
Fuel rules, electric fuel deferred costs upper threshold				101.00%
Fuel rules, electric fuel deferred costs lower threshold				99.00%
PSCW [Member] | Fuel Rules refund 2020 [Member] | MGE [Member]
Fuel Rules [Abstract]
Return of electric fuel credit, total	$ 3.2
PSCW [Member] | Rate Matters For Future Periods [Member] | MGE [Member]
Rate Proceedings [Abstract]
Authorized return on equity, percentage		9.80%	9.80%
Approved equity capital structure, percentage		55.60%	55.60%
Electric Rate Proceeding [Member] | PSCW [Member] | MGE [Member]
Rate Proceedings [Abstract]
Authorized rate increase (decrease), percentage				0.00%	(0.84%)	(2.24%)
Authorized rate increase (decrease), amount					$ (3.4)	$ (9.2)
Effects Of The Tax Cuts And Jobs Act [Abstract]
Return of unprotected excess deferred taxes				$ 18.2
Electric Rate Proceeding [Member] | PSCW [Member] | Rate Matters For Future Periods [Member] | MGE [Member]
Rate Proceedings [Abstract]
Proposed rate increase (decrease), percentage			8.81%
Gas Rate Proceeding [Member] | PSCW [Member] | MGE [Member]
Rate Proceedings [Abstract]
Authorized rate increase (decrease), percentage				4.00%	1.46%	1.06%
Authorized rate increase (decrease), amount					$ 2.4	$ 1.7
Gas Rate Proceeding [Member] | PSCW [Member] | Rate Matters For Future Periods [Member] | MGE [Member]
Rate Proceedings [Abstract]
Proposed rate increase (decrease), percentage		0.96%	2.15%