Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 163,400	$ 145,873	$ 524,686	$ 444,518
Equity in earnings of investment			6,626	7,440
Net income (loss)	33,720	34,917	89,901	92,701
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	132,876	121,639	354,915	324,110
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	30,310	24,020	169,305	119,944
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	214	214	466	464
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	163,400	145,873	524,686	444,518
Equity in earnings of investment	1,499	2,532	6,626	7,440
Net income (loss)	33,720	34,917	89,901	92,701
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	132,900	121,728	354,991	324,426
Equity in earnings of investment	0	0	0	0
Net income (loss)	27,619	27,833	55,248	59,979
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	42,775	30,709	195,950	134,321
Equity in earnings of investment	0	0	0	0
Net income (loss)	(394)	(218)	12,782	11,615
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,619	10,438	31,539	31,059
Equity in earnings of investment	0	0	0	0
Net income (loss)	5,576	5,386	16,451	15,935
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Equity in earnings of investment	1,499	2,532	6,626	7,440
Net income (loss)	1,091	1,842	4,821	5,413
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)	(172)	74	599	(241)
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(22,894)	(17,002)	(57,794)	(45,288)
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	24	89	76	316
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	12,465	6,689	26,645	14,377
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,405	10,224	31,073	30,595
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	163,400	145,873	524,686	444,518
Net income (loss)	27,198	27,374	68,534	70,774
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	132,876	121,639	354,915	324,110
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	30,310	24,020	169,305	119,944
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	214	214	466	464
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	163,400	145,873	524,686	444,518
Net income (loss)	27,198	27,374	68,534	70,774
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	132,900	121,728	354,991	324,426
Net income (loss)	27,619	27,833	55,248	59,979
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	42,775	30,709	195,950	134,321
Net income (loss)	(394)	(218)	12,782	11,615
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,619	10,438	31,539	31,059
Net income (loss)	5,576	5,386	16,451	15,935
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(22,894)	(17,002)	(57,794)	(45,288)
Net income (loss)	(5,603)	(5,627)	(15,947)	(16,755)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	24	89	76	316
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	12,465	6,689	26,645	14,377
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 10,405	$ 10,224	$ 31,073	$ 30,595