Schedule I - Condensed Parent Company Finanical Statements (Details-Balance Sheet) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets, Current [Abstract]
Cash and cash equivalents	$ 21,302	$ 11,140
Other current assets	14,229	15,587
Total Current Assets	227,265	238,197
Other deferred assets and other
Other deferred assets and other	26,285	20,741
Investments:
Other investments	2,298	2,298
Total investments	118,035	112,823
Total Assets	2,827,959	2,675,458
Current Liabilities:
Accounts payable to affiliates, current	77,466	65,451
Other current liabilities	7,418	8,003
Total Current Liabilities	125,563	157,156
Other Credits:
Deferred income taxes	316,397	279,029
Other deferred liabilities and other	64,553	61,682
Total Other Credits	708,561	659,407
Shareholders' Equity:
Retained earnings	764,133	707,160
Total Common Shareholders' Equity	1,230,138	1,140,073	$ 1,081,674	$ 1,027,468
Commitments and contingencies (see Footnote 3)
Total Liabilities and Capitalization	2,827,959	2,675,458
MGE Energy [Member]
Assets, Current [Abstract]
Cash and cash equivalents	3,195	4,353
Other current assets	3,284	2,395
Total Current Assets	6,479	6,748
Other deferred assets and other
Other deferred assets and other	163	210
Investments:
Investments in affiliates	1,236,884	1,148,134
Other investments	22,785	21,714
Total investments	1,259,669	1,169,848
Total Assets	1,266,311	1,176,806
Current Liabilities:
Accounts payable to affiliates, current	591	572
Other current liabilities	14	1,650
Total Current Liabilities	605	2,222
Other Credits:
Deferred income taxes	35,559	33,974
Accounts payable to affiliates	0	529
Other deferred liabilities and other	9	8
Total Other Credits	35,568	34,511
Shareholders' Equity:
Common shareholders' equity	466,005	432,913
Retained earnings	764,133	707,160
Total Common Shareholders' Equity	1,230,138	1,140,073
Commitments and contingencies (see Footnote 3)
Total Liabilities and Capitalization	$ 1,266,311	$ 1,176,806