Pension Plans and Other Postretirement Benefits (Details-2) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Amortization of:
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Transition Asset (Obligation), Statement of Income or Comprehensive Income [Extensible Enumeration]		Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]		Nonoperating Income (Expense)
Defined Benefit Plan, Deferred Pension and Other Postretirement Benefit Plan Costs Recovered [Abstract]
Deferred (recognized) pension and OPEB costs		$ (1,000)	$ (4,300)	$ (900)
Deferred savings from current year employee benefit costs		1,500	8,100
Return savings from prior year employee benefit costs		4,200
Pension Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	[1]	5,064	5,730	5,296
Interest cost	[1]	11,161	9,109	12,210
Expected return on assets	[1]	(31,391)	(29,487)	(27,229)
Amortization of:
Transition obligation	[1]	0	0	0
Prior service (credit) cost	[1]	(20)	(124)	(114)
Actuarial loss	[1]	2,416	6,646	5,357
Net periodic benefit cost (credit)	[1]	(12,770)	(8,126)	(4,480)
Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	[1]	1,293	1,448	1,264
Interest cost	[1]	1,940	1,549	2,278
Expected return on assets	[1]	(3,365)	(3,277)	(3,154)
Amortization of:
Transition obligation	[1]	3	3	3
Prior service (credit) cost	[1]	(297)	(1,518)	(2,669)
Actuarial loss	[1]	145	493	217
Net periodic benefit cost (credit)	[1]	$ (281)	$ (1,302)	$ (2,061)

[1] As approved by the PSCW, MGE is allowed to defer differences between actual employee benefit plan costs and costs reflected in current rates. The deferred costs may be recovered or refunded in MGE's next rate filing. For the years ended December 31, 2022, 2021, and 2020 MGE recovered approximately $1.0 million, $4.3 million, and $0.9 million, respectively, of pension and other postretirement costs. The recovery of these costs reduced the amount previously deferred and has not been reflected in the table above. See Footnote 8 for further information. For the years ended December 31, 2022 and 2021, MGE deferred and recorded as a regulatory liability $1.5 million and $8.1 million, respectively, of savings from employee benefit plan costs. For the year ended December 31, 2022, MGE refunded in rates $4.2 million of savings from 2021 employee benefit plan costs. The deferred savings has not been reflected in the table above. See Footnote 8 for additional information.