Schedule I - Condensed Parent Company Finanical Statements (Details-Balance Sheet) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 17,438	$ 44,738
Other current assets	11,183	11,394
Total Current Assets	199,371	209,519
Other deferred assets and other
Other deferred assets and other	27,548	22,259
Investments:
Other investments	2,324	2,308
Total investments	98,754	94,676
Total Assets	2,371,906	2,253,651	$ 2,081,664
Current Liabilities:
Other current liabilities	8,468	6,015
Total Current Liabilities	117,847	190,926
Other Credits:
Deferred income taxes	231,149	231,471
Other deferred liabilities and other	91,690	72,211
Total Other Credits	612,380	567,422
Shareholders' Equity:
Retained earnings	596,402	545,429
Total Common Shareholders' Equity	1,027,468	976,000	$ 855,676	$ 816,644
Commitments and contingencies (see Footnote 3)
Total Liabilities and Capitalization	2,371,906	2,253,651
MGE Energy [Member]
Current Assets:
Cash and cash equivalents	6,959	37,375
Other current assets	1,681	1,494
Total Current Assets	8,640	38,869
Other deferred assets and other
Other deferred assets and other	244	364
Investments:
Investments in affiliates	1,036,347	953,810
Other investments	18,927	15,634
Total investments	1,055,274	969,444
Total Assets	1,064,158	1,008,677
Current Liabilities:
Accounts payable to affiliates	548	530
Other current liabilities	2,516	66
Total Current Liabilities	3,064	596
Other Credits:
Deferred income taxes	32,014	29,926
Accounts payable to affiliates	1,589	2,118
Other deferred liabilities and other	23	37
Total Other Credits	33,626	32,081
Shareholders' Equity:
Common shareholders' equity	431,066	430,571
Retained earnings	596,402	545,429
Total Common Shareholders' Equity	1,027,468	976,000
Commitments and contingencies (see Footnote 3)
Total Liabilities and Capitalization	$ 1,064,158	$ 1,008,677