Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 40,660		$ 41,169
Receivable - margin account	2,500		2,477
Accounts receivable, less reserves	38,090	[1]	36,744	[2]
Other accounts receivables, less reserves	4,500	[3]	5,318	[4]
Unbilled revenues	20,706		25,754
Materials and supplies, at average cost	16,047		14,758
Fossil fuel	8,238		5,468
Stored natural gas, at average cost	10,385		19,575
Prepaid taxes	20,118		22,251
Regulatory assets - current	10,665		7,347
Other current assets	7,095		8,270
Total Current Assets	179,004		189,131
Regulatory assets	228,162		205,835
Other deferred assets and other	7,011		8,018
Property, Plant, and Equipment:
Property, plant, and equipment, net	966,069		961,511
Construction work in progress	40,854		34,055
Total Property, Plant, and Equipment	1,006,923		995,566
Investments	61,197		60,332
Total Assets	1,482,297		1,458,882
Current Liabilities:
Long-term debt due within one year	2,667		2,667
Accounts payable	32,000		34,532
Accrued interest and taxes	4,542		4,085
Accrued payroll related items	7,895		9,987
Deferred income taxes	862		3,020
Derivative liabilities	8,198		4,568
Other current liabilities	6,047		4,215
Total Current Liabilities	62,211		63,074
Other Credits:
Deferred income taxes	210,999		199,850
Investment tax credit - deferred	1,715		1,780
Regulatory liabilities	18,387		20,463
Accrued pension and other postretirement benefits	165,304		183,622
Derivative liabilities	60,880		34,908
Other deferred liabilities and other	44,388		43,330
Total Other Credits	501,673		483,953
Capitalization:
Common shareholders equity	558,164		550,952
Long-term debt	360,249		360,903
Total Capitalization	918,413		911,855
Commitments and contingencies (see Footnote 8)	0		0
Total Liabilities and Capitalization	1,482,297		1,458,882
MGE [Member]
Current Assets:
Cash and cash equivalents	14,659		13,898
Receivable - margin account	2,500		2,477
Accounts receivable, less reserves	37,088	[1]	35,765	[2]
Affiliate receivables	609		605
Other accounts receivables, less reserves	4,486	[3]	5,301	[4]
Unbilled revenues	20,706		25,754
Materials and supplies, at average cost	16,047		14,758
Fossil fuel	8,238		5,468
Stored natural gas, at average cost	10,385		19,575
Prepaid taxes	20,685		21,977
Regulatory assets - current	10,665		7,347
Other current assets	7,080		8,245
Total Current Assets	153,148		161,170
Affiliate receivable long-term	6,751		6,884
Regulatory assets	228,162		205,835
Other deferred assets and other	6,502		7,286
Property, Plant, and Equipment:
Property, plant, and equipment, net	965,565		961,007
Construction work in progress	40,854		34,055
Total Property, Plant, and Equipment	1,006,419		995,062
Investments	58,386		57,556
Total Assets	1,459,368		1,433,793
Current Liabilities:
Long-term debt due within one year	2,667		2,667
Accounts payable	32,000		34,532
Affiliate payables	1,822		2,152
Accrued interest and taxes	4,495		4,037
Accrued payroll related items	7,895		9,987
Deferred income taxes	927		3,020
Derivative liabilities	8,198		4,568
Other current liabilities	5,798		3,997
Total Current Liabilities	63,802		64,960
Other Credits:
Deferred income taxes	207,541		196,550
Investment tax credit - deferred	1,715		1,780
Regulatory liabilities	18,387		20,463
Accrued pension and other postretirement benefits	165,304		183,622
Derivative liabilities	60,880		34,908
Other deferred liabilities and other	44,388		43,330
Total Other Credits	498,215		480,653
Capitalization:
Common shareholders equity	416,324		412,926
Noncontrolling interest	120,778		114,351
Total Equity	537,102		527,277
Long-term debt	360,249		360,903
Total Capitalization	897,351		888,180
Commitments and contingencies (see Footnote 8)	0		0
Total Liabilities and Capitalization	$ 1,459,368		$ 1,433,793

[1] less reserves of $3,775

[2] less reserves of $3,662

[3] less reserves of $636

[4] less reserves of $439