Schedule I - Condensed Parent Company Finanical Statements (Details-Comprehensive Income Statement Parentheticals) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Income Statements, Captions [Line Items]
Unrealized gain (loss) on available-for-sale securities, taxes	$ 189	$ (12)	$ (10)
Reclassification of realized gain on available-for-sale securities, taxes	0	0	(10)
MGE Energy [Member]
Condensed Income Statements, Captions [Line Items]
Unrealized gain (loss) on available-for-sale securities, taxes	189	(12)	(10)
Reclassification of realized gain on available-for-sale securities, taxes	$ 0	$ 0	$ (10)

Tax effect of unrealized holding gain (loss) before reclassification adjustments and transfers on available-for-sale securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph c(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e640-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 25

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (e,f)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

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