Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Operating revenues	$ 168,480	$ 160,528	$ 505,529	$ 525,779
Equity in earnings of investment			8,427	7,930
Net Income (Loss)	40,939	37,857	98,547	97,616
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	147,790	138,891	384,298	377,627
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	20,476	21,424	120,761	147,677
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	214	213	470	475
Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	168,480	160,528	505,529	525,779
Equity in earnings of investment	2,901	2,690	8,427	7,930
Net Income (Loss)	40,939	37,857	98,547	97,616
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	147,746	139,403	384,144	378,280
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	35,035	31,126	66,458	65,996
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	24,683	24,971	132,352	160,655
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	(2,026)	(801)	8,638	10,539
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	11,266	10,611	33,295	31,618
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	6,101	5,627	17,968	16,667
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Equity in earnings of investment	2,901	2,690	8,427	7,930
Net Income (Loss)	2,112	1,957	6,130	5,770
Operating Segments [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	(283)	(52)	(647)	(1,356)
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(15,215)	(14,457)	(44,262)	(44,774)
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	0	0	0	0
Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	(44)	512	(154)	653
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,207	3,547	11,591	12,978
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	11,052	10,398	32,825	31,143
Consolidation Elimination Entries [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Consolidation Elimination Entries [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
MGE [Member]
Segment Reporting Information [Line Items]
Operating revenues	168,480	160,528	505,529	525,779
Net Income (Loss)	33,333	30,465	75,924	76,820
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	147,790	138,891	384,298	377,627
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	20,476	21,424	120,761	147,677
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	214	213	470	475
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	168,480	160,528	505,529	525,779
Net Income (Loss)	33,333	30,465	75,924	76,820
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	147,746	139,403	384,144	378,280
Net Income (Loss)	35,035	31,126	66,458	65,996
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	24,683	24,971	132,352	160,655
Net Income (Loss)	(2,026)	(801)	8,638	10,539
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	11,266	10,611	33,295	31,618
Net Income (Loss)	6,101	5,627	17,968	16,667
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(15,215)	(14,457)	(44,262)	(44,774)
Net Income (Loss)	(5,777)	(5,487)	(17,140)	(16,382)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	(44)	512	(154)	653
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,207	3,547	11,591	12,978
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 11,052	$ 10,398	$ 32,825	$ 31,143