Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current Assets:
Cash and cash equivalents	$ 87,911	$ 68,813
Accounts receivable, less reserves	37,685	44,890
Other accounts receivables, less reserves	5,390	5,352
Unbilled revenues	22,688	31,982
Materials and supplies, at average cost	17,991	16,662
Fossil fuel	4,410	5,206
Stored natural gas, at average cost	12,061	13,988
Prepaid taxes	17,420	19,106
Regulatory assets - current	3,563	6,377
Other current assets	9,663	8,225
Total Current Assets	218,782	220,601
Regulatory assets	98,268	107,166
Pension benefits	16,985	15,071
Other deferred assets and other	6,337	8,046
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,112,755	1,018,809
Construction work in progress	73,710	141,415
Total Property, Plant, and Equipment	1,186,465	1,160,224
Investments	70,126	67,952
Total Assets	1,596,963	1,579,060
Current Liabilities:
Long-term debt due within one year	4,141	4,102
Accounts payable	43,078	43,684
Accrued interest and taxes	4,902	5,661
Accrued payroll related items	8,790	10,731
Deferred income taxes	1,267	1,711
Regulatory liabilities - current	10,021	13,538
Derivative liabilities	6,300	7,750
Other current liabilities	8,139	9,489
Total Current Liabilities	86,638	96,666
Other Credits:
Deferred income taxes	302,337	284,791
Investment tax credit - deferred	1,294	1,413
Regulatory liabilities	21,566	19,792
Accrued pension and other postretirement benefits	49,944	49,184
Derivative liabilities	45,490	57,930
Other deferred liabilities and other	51,993	52,360
Total Other Credits	472,624	465,470
Capitalization:
Common shareholders equity	640,355	617,510
Long-term debt	397,346	399,414
Total Capitalization	1,037,701	1,016,924
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	1,596,963	1,579,060
MGE [Member]
Current Assets:
Cash and cash equivalents	26,284	14,808
Accounts receivable, less reserves	37,685	44,890
Affiliate receivables	611	534
Other accounts receivables, less reserves	5,329	5,274
Unbilled revenues	22,688	31,982
Materials and supplies, at average cost	17,991	16,662
Fossil fuel	4,410	5,206
Stored natural gas, at average cost	12,061	13,988
Prepaid taxes	22,315	23,934
Regulatory assets - current	3,563	6,377
Other current assets	9,654	8,197
Total Current Assets	162,591	171,852
Affiliate receivable long-term	5,560	5,825
Regulatory assets	98,268	107,166
Pension benefits	16,985	15,071
Other deferred assets and other	4,381	6,138
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,111,845	1,017,877
Construction work in progress	73,710	141,415
Total Property, Plant, and Equipment	1,185,555	1,159,292
Investments	67,249	65,299
Total Assets	1,540,589	1,530,643
Current Liabilities:
Long-term debt due within one year	4,141	4,102
Accounts payable	43,077	43,684
Accrued interest and taxes	4,893	6,040
Accrued payroll related items	8,790	10,731
Deferred income taxes	2,279	2,723
Regulatory liabilities - current	10,021	13,538
Derivative liabilities	6,300	7,750
Other current liabilities	7,789	6,446
Total Current Liabilities	87,290	95,014
Other Credits:
Deferred income taxes	296,047	279,085
Investment tax credit - deferred	1,294	1,413
Regulatory liabilities	21,566	19,792
Accrued pension and other postretirement benefits	49,944	49,184
Derivative liabilities	45,490	57,930
Other deferred liabilities and other	51,993	52,357
Total Other Credits	466,334	459,761
Capitalization:
Common shareholders equity	469,298	457,491
Noncontrolling interest	120,321	118,963
Total Equity	589,619	576,454
Long-term debt	397,346	399,414
Total Capitalization	986,965	975,868
Commitments and contingencies (see Footnote 8)
Total Liabilities and Capitalization	$ 1,540,589	$ 1,530,643