Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents		$ 17,438	$ 44,738
Accounts receivable, less reserves		46,205	41,384
Other accounts receivables, less reserves		16,094	7,300
Unbilled revenues		34,812	27,511
Materials and supplies, at average cost		29,863	32,513
Fuel for electric generation, at average cost		6,429	6,356
Stored natural gas, at average cost		15,668	8,396
Prepaid taxes		20,214	15,179
Regulatory assets - current		1,465	14,748
Other current assets		11,183	11,394
Total Current Assets		199,371	209,519
Other long-term receivables		1,155	1,435
Regulatory assets		107,547	142,504
Pension and other postretirement benefit asset		58,757	13,873
Other deferred assets and other		27,548	22,259
Property, Plant, and Equipment:
In-service utility plant, net		1,828,171	1,630,286
Construction work in progress		50,603	139,099
Total Property, Plant, and Equipment		1,878,774	1,769,385
Investments		98,754	94,676
Total Assets		2,371,906	2,253,651
Current Liabilities:
Long-term debt due within one year		4,889	4,771
Short-term debt	[1]	5,500	52,500
Accounts payable		64,149	54,642
Accrued interest and taxes		10,385	8,539
Accrued payroll related items		12,951	12,635
Regulatory liabilities - current		9,365	41,664
Derivative liabilities		2,140	10,160
Other current liabilities		8,468	6,015
Total Current Liabilities		117,847	190,926
Other Credits:
Deferred income taxes		231,149	231,471
Investment tax credit - deferred		44,836	21,821
Regulatory liabilities		154,298	142,239
Accrued pension and other postretirement benefits		73,085	78,168
Derivative liabilities		0	3,980
Finance lease liabilities		17,322	17,532
Other deferred liabilities and other		91,690	72,211
Total Other Credits		612,380	567,422
Common shareholders' equity:
Common stock		36,163	36,163
Additional paid-in capital		394,903	394,408
Retained earnings		596,402	545,429
Total Common Shareholders' Equity		1,027,468	976,000
Long-term debt		614,211	519,303
Total Capitalization		1,641,679	1,495,303
Commitments and contingencies (see Footnote 16)
Total Liabilities and Capitalization		2,371,906	2,253,651
MGE [Member]
Current Assets:
Cash and cash equivalents		6,401	4,103
Accounts receivable, less reserves		46,205	41,384
Affiliate receivables		558	532
Other accounts receivables, less reserves		16,092	7,295
Unbilled revenues		34,812	27,511
Materials and supplies, at average cost		29,863	32,513
Fuel for electric generation, at average cost		6,429	6,356
Stored natural gas, at average cost		15,668	8,396
Prepaid taxes		19,379	14,848
Regulatory assets - current		1,465	14,748
Other current assets		11,071	11,326
Total Current Assets		187,943	169,012
Affiliate receivable long-term		1,589	2,118
Regulatory assets		107,547	142,504
Pension and other postretirement benefit asset		58,757	13,873
Other deferred assets and other		27,907	22,448
Property, Plant, and Equipment:
In-service utility plant, net		1,828,199	1,630,314
Construction work in progress		50,603	139,099
Total Property, Plant, and Equipment		1,878,802	1,769,413
Investments		230	603
Total Assets		2,262,775	2,119,971
Current Liabilities:
Long-term debt due within one year		4,889	4,771
Short-term debt		5,500	52,500
Accounts payable		64,130	54,576
Accrued interest and taxes		10,649	10,405
Accrued payroll related items		12,951	12,635
Regulatory liabilities - current		9,365	41,664
Derivative liabilities		2,140	10,160
Other current liabilities		5,968	6,042
Total Current Liabilities		115,592	192,753
Other Credits:
Deferred income taxes		198,885	200,390
Investment tax credit - deferred		44,836	21,821
Regulatory liabilities		154,298	142,239
Accrued pension and other postretirement benefits		73,085	78,168
Derivative liabilities		0	3,980
Finance lease liabilities		17,322	17,532
Other deferred liabilities and other		92,152	72,173
Total Other Credits		580,578	536,303
Common shareholders' equity:
Common stock		17,348	17,348
Additional paid-in capital		252,917	252,917
Retained earnings		533,542	460,151
Total Common Shareholders' Equity		803,807	730,416
Noncontrolling interest		148,587	141,196
Total Equity		952,394	871,612
Long-term debt		614,211	519,303
Total Capitalization		1,566,605	1,390,915
Commitments and contingencies (see Footnote 16)
Total Liabilities and Capitalization		$ 2,262,775	$ 2,119,971

[1] MGE Energy short-term borrowings include MGE Energy and MGE lines of credit and MGE commercial paper.