Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Schedule I - Condensed Parent Company Finanical Statements (Details-Notes 1) (Line of Credit [Member], USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Credit facilities [Line Items]
Lines of credit borrowing capacity	$ 115,000,000	$ 115,000,000	$ 115,000,000
MGE Energy [Member]
Credit facilities [Line Items]
Lines of credit borrowing capacity	40,000,000
Available lines of credit	$ 40,000,000