Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Revenues:
Electric revenues	$ 394,372	$ 408,980	$ 402,001
Gas revenues	144,261	159,875	157,767
Total Operating Revenues	538,633	568,855	559,768
Operating Expenses:
Fuel for electric generation	41,684	51,954	56,141
Purchased power	42,883	41,474	50,807
Cost of gas sold	63,697	79,775	84,968
Other operations and maintenance	186,430	193,322	177,823
Depreciation and amortization	74,188	71,562	56,412
Other general taxes	19,754	19,858	19,410
Total Operating Expenses	428,636	457,945	445,561
Operating Income	109,997	110,910	114,207
Other income, net	25,365	18,811	17,055
Interest expense, net	(23,521)	(23,063)	(19,609)
Income before income taxes	111,841	106,658	111,653
Income tax provision	(19,423)	(19,784)	(27,434)
Net Income Including Noncontrolling Interest	92,418	86,874	84,219
Net Income	$ 92,418	$ 86,874	$ 84,219
Earnings Per Share of Common Stock (basic and diluted)	$ 2.60	$ 2.51	$ 2.43
Dividends per share of common stock	$ 1.45	$ 1.38	$ 1.32
Weighted Average Shares Outstanding (basic and diluted)	35,612	34,668	34,668
MGE [Member]
Operating Revenues:
Electric revenues	$ 394,372	$ 408,980	$ 402,001
Gas revenues	144,261	159,875	157,767
Total Operating Revenues	538,633	568,855	559,768
Operating Expenses:
Fuel for electric generation	41,684	51,954	56,141
Purchased power	42,883	41,474	50,807
Cost of gas sold	63,697	79,775	84,968
Other operations and maintenance	185,450	192,440	176,762
Depreciation and amortization	74,188	71,562	56,412
Other general taxes	19,750	19,858	19,410
Total Operating Expenses	427,652	457,063	444,500
Operating Income	110,981	111,792	115,268
Other income, net	15,019	10,703	10,426
Interest expense, net	(23,642)	(24,298)	(21,197)
Income before income taxes	102,358	98,197	104,497
Income tax provision	(16,835)	(17,418)	(25,461)
Net Income Including Noncontrolling Interest	85,523	80,779	79,036
Less Net Income Attributable to Noncontrolling Interest, net of tax	(22,393)	(22,349)	(22,552)
Net Income	$ 63,130	$ 58,430	$ 56,484