Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 41,288		$ 41,169
Receivable - margin account	2,695		2,477
Accounts receivable, less reserves	30,551	[1]	36,744	[2]
Other accounts receivables, less reserves	5,381	[3]	5,318	[4]
Unbilled revenues	22,311		25,754
Materials and supplies, at average cost	16,875		14,758
Fossil fuel	8,928		5,468
Stored natural gas, at average cost	12,716		19,575
Prepaid taxes	21,242		22,251
Regulatory assets - current	9,643		7,347
Other current assets	7,056		8,270
Total Current Assets	178,686		189,131
Regulatory assets	235,570		205,835
Other deferred assets and other	6,830		8,018
Property, Plant, and Equipment:
Property, plant, and equipment, net	969,707		961,511
Construction work in progress	53,434		34,055
Total Property, Plant, and Equipment	1,023,141		995,566
Investments	62,323		60,332
Total Assets	1,506,550		1,458,882
Current Liabilities:
Long-term debt due within one year	2,667		2,667
Accounts payable	28,238		34,532
Accrued interest and taxes	4,131		4,085
Accrued payroll related items	7,789		9,987
Deferred income taxes	2,791		3,020
Derivative liabilities	10,180		4,568
Other current liabilities	6,324		4,215
Total Current Liabilities	62,120		63,074
Other Credits:
Deferred income taxes	215,151		199,850
Investment tax credit - deferred	1,650		1,780
Regulatory liabilities	21,170		20,463
Accrued pension and other postretirement benefits	167,028		183,622
Derivative liabilities	69,570		34,908
Other deferred liabilities and other	46,076		43,330
Total Other Credits	520,645		483,953
Capitalization:
Common shareholders equity	563,626		550,952
Long-term debt	360,159		360,903
Total Capitalization	923,785		911,855
Commitments and contingencies (see Footnote 8)	0		0
Total Liabilities and Capitalization	1,506,550		1,458,882
MGE [Member]
Current Assets:
Cash and cash equivalents	8,665		13,898
Receivable - margin account	2,695		2,477
Accounts receivable, less reserves	29,873	[1]	35,765	[2]
Affiliate receivables	670		605
Other accounts receivables, less reserves	5,370	[3]	5,301	[4]
Unbilled revenues	22,311		25,754
Materials and supplies, at average cost	16,875		14,758
Fossil fuel	8,928		5,468
Stored natural gas, at average cost	12,716		19,575
Prepaid taxes	22,082		21,977
Regulatory assets - current	9,643		7,347
Other current assets	7,046		8,245
Total Current Assets	146,874		161,170
Affiliate receivable long-term	6,619		6,884
Regulatory assets	235,570		205,835
Other deferred assets and other	6,208		7,286
Property, Plant, and Equipment:
Property, plant, and equipment, net	969,203		961,007
Construction work in progress	53,434		34,055
Total Property, Plant, and Equipment	1,022,637		995,062
Investments	59,395		57,556
Total Assets	1,477,303		1,433,793
Current Liabilities:
Long-term debt due within one year	2,667		2,667
Accounts payable	28,238		34,532
Affiliate payables	1,491		2,152
Accrued interest and taxes	4,083		4,037
Accrued payroll related items	7,789		9,987
Deferred income taxes	2,856		3,020
Derivative liabilities	10,180		4,568
Other current liabilities	6,126		3,997
Total Current Liabilities	63,430		64,960
Other Credits:
Deferred income taxes	211,529		196,550
Investment tax credit - deferred	1,650		1,780
Regulatory liabilities	21,170		20,463
Accrued pension and other postretirement benefits	167,028		183,622
Derivative liabilities	69,570		34,908
Other deferred liabilities and other	46,077		43,330
Total Other Credits	517,024		480,653
Capitalization:
Common shareholders equity	417,799		412,926
Noncontrolling interest	118,891		114,351
Total Equity	536,690		527,277
Long-term debt	360,159		360,903
Total Capitalization	896,849		888,180
Commitments and contingencies (see Footnote 8)	0		0
Total Liabilities and Capitalization	$ 1,477,303		$ 1,433,793

[1] less reserves of $3,727

[2] less reserves of $3,662

[3] less reserves of $616

[4] less reserves of $439