Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 208,938	$ 167,915
Equity in earnings of investment	2,504	2,444
Net Income	34,420	34,933
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	110,089	100,609
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	98,811	67,270
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	38	36
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	208,938	167,915
Equity in earnings of investment	2,504	2,444
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	110,207	100,882
Equity in earnings of investment	0	0
Net Income	14,617	18,024
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	104,932	72,081
Equity in earnings of investment	0	0
Net Income	12,084	10,556
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,353	10,209
Equity in earnings of investment	0	0
Net Income	5,352	5,194
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Equity in earnings of investment	2,504	2,444
Net Income	1,822	1,778
Operating Segments [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Equity in earnings of investment	0	0
Net Income	545	(619)
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(16,554)	(15,257)
Equity in earnings of investment	0	0
Net Income	0	0
Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	118	273
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,121	4,811
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,315	10,173
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	208,938	167,915
Net Income	27,297	28,273
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	110,089	100,609
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	98,811	67,270
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	38	36
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	208,938	167,915
Net Income	27,297	28,273
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	110,207	100,882
Net Income	14,617	18,024
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	104,932	72,081
Net Income	12,084	10,556
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,353	10,209
Net Income	5,352	5,194
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(16,554)	(15,257)
Net Income	(4,756)	(5,501)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	118	273
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	6,121	4,811
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 10,315	$ 10,173