Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 147,998	$ 152,348	$ 365,251	$ 361,286
Equity in earnings of investment			5,240	5,127
Net income (loss)	28,681	21,761	59,759	56,181
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	121,492	111,950	238,736	222,039
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	26,291	40,184	126,253	138,995
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	215	214	262	252
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	147,998	152,348	365,251	361,286
Equity in earnings of investment	2,629	2,623	5,240	5,127
Net income (loss)	28,681	21,761	59,759	56,181
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	121,685	111,884	238,877	222,091
Equity in earnings of investment	0	0	0	0
Net income (loss)	21,556	13,012	34,870	27,629
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	29,061	48,242	135,684	153,174
Equity in earnings of investment	0	0	0	0
Net income (loss)	581	1,093	11,340	13,177
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,410	10,567	21,007	20,920
Equity in earnings of investment	0	0	0	0
Net income (loss)	5,470	5,522	11,040	10,874
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Equity in earnings of investment	2,629	2,623	5,240	5,127
Net income (loss)	1,914	1,908	3,813	3,730
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)	(840)	226	(1,304)	771
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(13,158)	(18,345)	(30,317)	(34,899)
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	193	(66)	141	52
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	2,770	8,058	9,431	14,179
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,195	10,353	20,745	20,668
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	147,998	152,348	365,251	361,286
Net income (loss)	22,232	14,039	46,355	41,336
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	121,492	111,950	238,736	222,039
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	26,291	40,184	126,253	138,995
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	215	214	262	252
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	147,998	152,348	365,251	361,286
Net income (loss)	22,232	14,039	46,355	41,336
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	121,685	111,884	238,877	222,091
Net income (loss)	21,556	13,012	34,870	27,629
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	29,061	48,242	135,684	153,174
Net income (loss)	581	1,093	11,340	13,177
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,410	10,567	21,007	20,920
Net income (loss)	5,470	5,522	11,040	10,874
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(13,158)	(18,345)	(30,317)	(34,899)
Net income (loss)	(5,375)	(5,588)	(10,895)	(10,344)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	193	(66)	141	52
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	2,770	8,058	9,431	14,179
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 10,195	$ 10,353	$ 20,745	$ 20,668