Consolidated Balance Sheets (Unaudited) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 61,112,000	$ 83,102,000
Accounts receivable, less reserves	35,805,000	43,593,000
Other accounts receivables, less reserves	7,867,000	6,262,000
Unbilled revenues	20,926,000	28,243,000
Materials and supplies, at average cost	28,019,000	24,093,000
Fuel for electric generation, at average cost	8,339,000	6,599,000
Stored natural gas, at average cost	11,402,000	11,303,000
Prepaid taxes	11,518,000	16,215,000
Regulatory assets - current	10,777,000	9,477,000
Assets held for sale	0	3,080,000
Other current assets	8,631,000	8,593,000
Total Current Assets	204,396,000	240,560,000
Other long-term receivables	2,343,000	2,709,000
Regulatory assets	144,482,000	145,424,000
Other deferred assets and other	17,096,000	12,488,000
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,524,925,000	1,369,766,000
Construction work in progress	88,050,000	139,671,000
Total Property, Plant, and Equipment	1,612,975,000	1,509,437,000
Investments	85,681,000	78,000,000
Total Assets	2,066,973,000	1,988,618,000
Current Liabilities:
Long-term debt due within one year	4,632,000	4,553,000
Short-term debt	54,500,000	13,000,000
Accounts payable	39,139,000	46,158,000
Accrued interest and taxes	5,570,000	7,384,000
Accrued payroll related items	11,090,000	13,044,000
Regulatory liabilities - current	15,606,000	13,826,000
Derivative liabilities	10,390,000	8,550,000
Other current liabilities	11,124,000	14,113,000
Total Current Liabilities	152,051,000	120,628,000
Other Credits:
Deferred income taxes	239,433,000	231,952,000
Investment tax credit - deferred	786,000	818,000
Regulatory liabilities	162,088,000	165,638,000
Accrued pension and other postretirement benefits	64,274,000	67,483,000
Derivative liabilities	18,600,000	23,980,000
Finance lease liabilities	17,657,000	1,771,000
Other deferred liabilities and other	70,691,000	66,361,000
Total Other Credits	573,529,000	558,003,000
Capitalization:
Common shareholders equity	851,234,000	816,644,000
Long-term debt	490,159,000	493,343,000
Total Capitalization	1,341,393,000	1,309,987,000
Commitments and contingencies (see Footnote 9)
Total Liabilities and Capitalization	2,066,973,000	1,988,618,000
MGE [Member]
Current Assets:
Cash and cash equivalents	4,656,000	4,843,000
Accounts receivable, less reserves	35,805,000	43,593,000
Affiliate receivables	540,000	621,000
Other accounts receivables, less reserves	7,863,000	6,111,000
Unbilled revenues	20,926,000	28,243,000
Materials and supplies, at average cost	28,019,000	24,093,000
Fuel for electric generation, at average cost	8,339,000	6,599,000
Stored natural gas, at average cost	11,402,000	11,303,000
Prepaid taxes	11,211,000	15,790,000
Regulatory assets - current	10,777,000	9,477,000
Assets held for sale	0	3,080,000
Other current assets	8,522,000	8,541,000
Total Current Assets	148,060,000	162,294,000
Affiliate receivable long-term	2,780,000	3,177,000
Regulatory assets	144,482,000	145,424,000
Other deferred assets and other	18,178,000	14,142,000
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,524,954,000	1,369,795,000
Construction work in progress	88,050,000	139,671,000
Total Property, Plant, and Equipment	1,613,004,000	1,509,466,000
Investments	523,000	388,000
Total Assets	1,927,027,000	1,834,891,000
Current Liabilities:
Long-term debt due within one year	4,632,000	4,553,000
Short-term debt	54,500,000	13,000,000
Accounts payable	39,104,000	46,165,000
Accrued interest and taxes	7,901,000	10,319,000
Accrued payroll related items	11,090,000	13,044,000
Regulatory liabilities - current	15,606,000	13,826,000
Derivative liabilities	10,390,000	8,550,000
Other current liabilities	11,125,000	11,614,000
Total Current Liabilities	154,348,000	121,071,000
Other Credits:
Deferred income taxes	210,886,000	204,616,000
Investment tax credit - deferred	786,000	818,000
Regulatory liabilities	162,088,000	165,638,000
Accrued pension and other postretirement benefits	64,274,000	67,483,000
Derivative liabilities	18,600,000	23,980,000
Finance lease liabilities	17,657,000	1,771,000
Other deferred liabilities and other	70,655,000	66,361,000
Total Other Credits	544,946,000	530,667,000
Capitalization:
Common shareholders equity	596,395,000	548,356,000
Noncontrolling interest	141,179,000	141,454,000
Total Equity	737,574,000	689,810,000
Long-term debt	490,159,000	493,343,000
Total Capitalization	1,227,733,000	1,183,153,000
Commitments and contingencies (see Footnote 9)
Total Liabilities and Capitalization	$ 1,927,027,000	$ 1,834,891,000