Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 152,348	$ 130,730	$ 361,286	$ 298,645
Equity in earnings of investment			5,127	4,908
Net Income	21,761	22,851	56,181	57,784
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	111,950	101,862	222,039	202,471
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	40,184	28,654	138,995	95,924
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	214	214	252	250
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	152,348	130,730	361,286	298,645
Equity in earnings of investment	2,623	2,464	5,127	4,908
Net Income	21,761	22,851	56,181	57,784
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	111,884	101,816	222,091	202,698
Equity in earnings of investment	0	0	0	0
Net Income	13,012	14,122	27,629	32,146
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	48,242	31,531	153,174	103,612
Equity in earnings of investment	0	0	0	0
Net Income	1,093	1,277	13,177	11,833
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,567	10,411	20,920	20,621
Equity in earnings of investment	0	0	0	0
Net Income	5,522	5,355	10,874	10,549
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Equity in earnings of investment	2,623	2,464	5,127	4,908
Net Income	1,908	1,793	3,730	3,571
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	226	304	771	(315)
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(18,345)	(13,028)	(34,899)	(28,286)
Equity in earnings of investment	0	0	0	0
Net Income	0	0	0	0
Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	(66)	(46)	52	227
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	8,058	2,877	14,179	7,688
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,353	10,197	20,668	20,371
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	152,348	130,730	361,286	298,645
Net Income	14,039	15,127	41,336	43,400
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	111,950	101,862	222,039	202,471
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	40,184	28,654	138,995	95,924
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	214	214	252	250
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	152,348	130,730	361,286	298,645
Net Income	14,039	15,127	41,336	43,400
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	111,884	101,816	222,091	202,698
Net Income	13,012	14,122	27,629	32,146
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	48,242	31,531	153,174	103,612
Net Income	1,093	1,277	13,177	11,833
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,567	10,411	20,920	20,621
Net Income	5,522	5,355	10,874	10,549
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(18,345)	(13,028)	(34,899)	(28,286)
Net Income	(5,588)	(5,627)	(10,344)	(11,128)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	(66)	(46)	52	227
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	8,058	2,877	14,179	7,688
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 10,353	$ 10,197	$ 20,668	$ 20,371