Pension Plans and Other Postretirement Benefits (Details-1) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan, Deferred Pension and Other Postretirement Benefit Plan Costs Recovered [Abstract]
Defined Contribution Plan, Cost		$ 6,500	$ 5,200	$ 5,400
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets as of January 1		447,884
Fair value of plan assets as of December 31		465,789	447,884
Amounts recognized in the consolidated balance sheets to reflect funded status of plans [Abstract]
Long-term asset		132,264	93,896
Long-term liability		(50,155)	(55,058)
Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Net benefit obligation as of January 1		346,460	335,288
Service cost		3,078	2,892	5,064
Interest cost		17,118	17,319	11,161
Plan participants' contributions		0	0
Actuarial loss (gain)	[1]	(16,669)	11,946
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment		0	0
Settlements	[2]	0	0
Gross benefits paid		(23,050)	(20,985)
Less: federal subsidy on benefits paid	[3]	0	0
Benefit obligation as of December 31		326,937	346,460	335,288
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets as of January 1		404,735	370,171
Actual return in plan assets		40,608	53,346
Employer contributions		2,175	2,203
Plan participants' contributions		0	0
Settlements		0	0
Gross benefits paid		(23,050)	(20,985)
Fair value of plan assets as of December 31		424,468	404,735	370,171
Funded Status as of December 31		97,531	58,275
Accumulated benefit obligation		311,000	328,400
Amounts recognized in the consolidated balance sheets to reflect funded status of plans [Abstract]
Long-term asset		131,418	93,896
Current liability		(2,441)	(2,387)
Long-term liability		(31,446)	(33,234)
Net asset (liability)		97,531	58,275
Amounts recognized in the consolidated balance sheets as regulatory asset [Abstract]
Net actuarial loss (gain)		3,699	33,237
Prior service (credit) cost		0	0
Transition obligation		0	0
Total		3,699	33,237
Projected benefit obligation in excess of plan assets [Abstract]
Projected benefit obligation with projected benefit obligation in excess of plan assets, end of year		33,887	35,621
Fair value of plan assets with projected benefit obligation in excess of plan assets, end of year		0	0
Accumulated benefit obligation in excess of plan assets [Abstract]
Accumulated benefit obligation with accumulated benefit obligation in excess of plan assets, end of year		32,463	34,387
Fair value of plan assets with accumulated benefit obligation in excess of plan assets, end of year		0	0
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Net benefit obligation as of January 1		64,973	63,828
Service cost		856	780	1,293
Interest cost		3,126	3,308	1,940
Plan participants' contributions		1,045	1,017
Actuarial loss (gain)	[1]	(3,769)	1,951
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment		0	(242)
Settlements	[2]	(1,227)	0
Gross benefits paid		(6,171)	(5,986)
Less: federal subsidy on benefits paid	[3]	351	317
Benefit obligation as of December 31		59,184	64,973	63,828
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets as of January 1		43,149	41,867
Actual return in plan assets		4,131	5,312
Employer contributions		682	939
Plan participants' contributions		1,045	1,017
Settlements		(1,515)	0
Gross benefits paid		(6,171)	(5,986)
Fair value of plan assets as of December 31		41,321	43,149	$ 41,867
Funded Status as of December 31		(17,863)	(21,824)
Medicare subsidy due to MGE		300	300
Amounts recognized in the consolidated balance sheets to reflect funded status of plans [Abstract]
Long-term asset		846	0
Current liability		0	0
Long-term liability		(18,709)	(21,824)
Net asset (liability)		(17,863)	(21,824)
Amounts recognized in the consolidated balance sheets as regulatory asset [Abstract]
Net actuarial loss (gain)		(7,191)	(1,626)
Prior service (credit) cost		0	(242)
Transition obligation		3	5
Total		(7,188)	(1,863)
Accumulated benefit obligation in excess of plan assets [Abstract]
Accumulated benefit obligation with accumulated benefit obligation in excess of plan assets, end of year		43,882	64,973
Fair value of plan assets with accumulated benefit obligation in excess of plan assets, end of year		$ 25,172	$ 43,149

[1] In 2024, higher discount rates were the primary driver of the actuarial gain.

[2] In August 2024, MGE entered into an agreement to transfer the mortality and investment risk, as well as the administration of, its employer-paid life insurance plan to a third party. MGE accounted for the settlement under the scope of ASC 715.

[3] In 2003, the Medicare Prescription Drug, Improvement and Modernization Act of 2003 was signed into law authorizing Medicare to provide prescription drug benefits to retirees. For both the years ended December 31, 2024 and 2023, the subsidy due to MGE was $0.3 million.