Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Operating revenues	$ 191,336	$ 217,253
Equity in earnings of investment	2,746	2,611
Net Income (Loss)	33,814	31,078
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	116,125	117,244
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	75,169	99,962
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	42	47
Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	191,336	217,253
Equity in earnings of investment	2,746	2,611
Net Income (Loss)	33,814	31,078
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	116,070	117,192
Equity in earnings of investment	0	0
Net Income (Loss)	15,763	13,314
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	80,381	106,623
Equity in earnings of investment	0	0
Net Income (Loss)	10,614	10,759
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,869	10,597
Equity in earnings of investment	0	0
Net Income (Loss)	5,823	5,570
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Equity in earnings of investment	2,746	2,611
Net Income (Loss)	1,996	1,899
Operating Segments [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Equity in earnings of investment	0	0
Net Income (Loss)	(382)	(464)
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(15,984)	(17,159)
Equity in earnings of investment	0	0
Net Income (Loss)	0	0
Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	(55)	(52)
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,212	6,661
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,827	10,550
Consolidation Elimination Entries [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Consolidation Elimination Entries [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
MGE [Member]
Segment Reporting Information [Line Items]
Operating revenues	191,336	217,253
Net Income (Loss)	26,603	24,123
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	116,125	117,244
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	75,169	99,962
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	42	47
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	191,336	217,253
Net Income (Loss)	26,603	24,123
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	116,070	117,192
Net Income (Loss)	15,763	13,314
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	80,381	106,623
Net Income (Loss)	10,614	10,759
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,869	10,597
Net Income (Loss)	5,823	5,570
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(15,984)	(17,159)
Net Income (Loss)	(5,597)	(5,520)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	(55)	(52)
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,212	6,661
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 10,827	$ 10,550