Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 160,528	$ 163,400	$ 525,779	$ 524,686
Equity in earnings of investment			7,930	6,626
Net Income (Loss)	37,857	33,720	97,616	89,901
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	138,891	132,876	377,627	354,915
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	21,424	30,310	147,677	169,305
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	213	214	475	466
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	160,528	163,400	525,779	524,686
Equity in earnings of investment	2,690	1,499	7,930	6,626
Net Income (Loss)	37,857	33,720	97,616	89,901
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	139,403	132,900	378,280	354,991
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	31,126	27,619	65,996	55,248
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	24,971	42,775	160,655	195,950
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	(801)	(394)	10,539	12,782
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,611	10,619	31,618	31,539
Equity in earnings of investment	0	0	0	0
Net Income (Loss)	5,627	5,576	16,667	16,451
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Equity in earnings of investment	2,690	1,499	7,930	6,626
Net Income (Loss)	1,957	1,091	5,770	4,821
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)	(52)	(172)	(1,356)	599
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(14,457)	(22,894)	(44,774)	(57,794)
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	512	24	653	76
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	3,547	12,465	12,978	26,645
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,398	10,405	31,143	31,073
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	160,528	163,400	525,779	524,686
Net Income (Loss)	30,465	27,198	76,820	68,534
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	138,891	132,876	377,627	354,915
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	21,424	30,310	147,677	169,305
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	213	214	475	466
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	160,528	163,400	525,779	524,686
Net Income (Loss)	30,465	27,198	76,820	68,534
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	139,403	132,900	378,280	354,991
Net Income (Loss)	31,126	27,619	65,996	55,248
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	24,971	42,775	160,655	195,950
Net Income (Loss)	(801)	(394)	10,539	12,782
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,611	10,619	31,618	31,539
Net Income (Loss)	5,627	5,576	16,667	16,451
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(14,457)	(22,894)	(44,774)	(57,794)
Net Income (Loss)	(5,487)	(5,603)	(16,382)	(15,947)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	512	24	653	76
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	3,547	12,465	12,978	26,645
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 10,398	$ 10,405	$ 31,143	$ 31,073