Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 11,269	$ 11,604
Accounts receivable, less reserves	43,819	55,407
Other accounts receivables, less reserves	17,270	11,418
Unbilled revenues	24,687	43,086
Materials and supplies, at average cost	35,329	33,465
Fuel for electric generation, at average cost	9,492	7,962
Stored natural gas, at average cost	27,595	32,848
Prepaid taxes	13,856	19,132
Regulatory assets - current	18,308	9,541
Other current assets	14,786	19,017
Total Current Assets	216,411	243,480
Regulatory assets	96,764	103,900
Pension benefit asset	74,087	68,872
Other deferred assets and other	21,485	24,365
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,902,032	1,865,352
Construction work in progress	168,504	105,748
Total Property, Plant, and Equipment	2,070,536	1,971,100
Investments	111,249	105,883
Total Assets	2,590,532	2,517,600
Current Liabilities:
Long-term debt due within one year	5,112	54,314
Short-term debt	22,000	70,500
Accounts payable	53,593	59,334
Accrued interest and taxes	7,368	7,868
Accrued payroll related items	13,155	13,064
Regulatory liabilities - current	13,462	11,925
Other current liabilities	8,148	8,057
Total Current Liabilities	122,838	225,062
Other Credits:
Deferred income taxes	271,453	252,190
Investment tax credit - deferred	47,369	48,735
Regulatory liabilities	155,026	156,988
Accrued pension and other postretirement benefits	54,531	53,607
Finance lease liabilities	17,932	17,108
Other deferred liabilities and other	96,102	96,990
Total Other Credits	642,413	625,618
Capitalization:
Common shareholders equity	1,135,253	1,081,674
Long-term debt	690,028	585,246
Total Capitalization	1,825,281	1,666,920
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	2,590,532	2,517,600
MGE [Member]
Current Assets:
Cash and cash equivalents	2,668	4,136
Accounts receivable, less reserves	43,819	55,407
Other accounts receivables, less reserves	17,268	11,416
Unbilled revenues	24,687	43,086
Materials and supplies, at average cost	35,329	33,465
Fuel for electric generation, at average cost	9,492	7,962
Stored natural gas, at average cost	27,595	32,848
Prepaid taxes	14,055	18,467
Regulatory assets - current	18,308	9,541
Other current assets	15,284	19,479
Total Current Assets	208,505	235,807
Regulatory assets	96,764	103,900
Pension benefit asset	74,087	68,872
Other deferred assets and other	21,611	24,817
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,902,060	1,865,380
Construction work in progress	168,504	105,748
Total Property, Plant, and Equipment	2,070,564	1,971,128
Investments	83	115
Total Assets	2,471,614	2,404,639
Current Liabilities:
Long-term debt due within one year	5,112	54,314
Short-term debt	22,000	70,500
Accounts payable	53,578	59,317
Accrued interest and taxes	7,323	7,912
Accrued payroll related items	13,155	13,064
Regulatory liabilities - current	13,462	11,925
Other current liabilities	8,148	6,062
Total Current Liabilities	122,778	223,094
Other Credits:
Deferred income taxes	237,414	219,258
Investment tax credit - deferred	47,369	48,735
Regulatory liabilities	155,026	156,988
Accrued pension and other postretirement benefits	54,531	53,607
Finance lease liabilities	17,932	17,108
Other deferred liabilities and other	98,198	98,217
Total Other Credits	610,470	593,913
Capitalization:
Common shareholders equity	901,043	854,223
Noncontrolling interest	147,295	148,163
Total Equity	1,048,338	1,002,386
Long-term debt	690,028	585,246
Total Capitalization	1,738,366	1,587,632
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	$ 2,471,614	$ 2,404,639