2.4.0.8010290 - Disclosure - New Accounting Pronouncementstruefalsefalse1false falsefalseFROM_Jan01_2013_TO_Jun30_2013http://www.sec.gov/CIK0001161728duration2013-01-01T00:00:002013-06-30T00:00:001true 1mgee_NewAccountingPronouncementsDisclosureAbstractmgee_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0New Accounting Pronouncements Disclosure [Abstract]2false 2us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse0012.       New Accounting Pronouncements - MGE Energy and MGE. a.       Presentation of Comprehensive Income.        In February 2013, the FASB issued authoritative guidance within the Codification's Comprehensive Income topic that provides guidance on the reporting of amounts reclassified out of accumulated other comprehensive income. Reclassification adjustments will be presented either on the financial statement where income is presented or as a separate disclosure in the notes to the financial statements. This authoritative guidance became effective January 1, 2013. The authoritative guidance had no effect on our financial statement presentation or notes to the financial statements. b.       Disclosures about Offsetting Assets and Liabilities.        In December 2011, the FASB issued authoritative guidance within the Codification's Balance Sheet topic that provides guidance on disclosures about offsetting assets and liabilities. The new disclosure requirements mandate that entities disclose both gross and net information for instruments and transactions eligible for offset in the balance sheet as well as instruments and transactions subject to a master netting arrangement. In addition, the standard requires disclosure of collateral received and posted in connections with a master netting arrangement. On January 31, 2013, the FASB issued additional authoritative guidance which clarified the scope of disclosures about offsetting assets and liabilities. The revised guidance limits the scope of the new balance sheet offsetting disclosures to derivatives, repurchase agreements, and securities lending transactions to the extent that they are (1) offset in the financial statements or (2) subject to an enforceable master netting arrangement or similar agreement. This authoritative guidance became effective January 1, 2013. The authoritative guidance did not have a financial impact, but required additional disclosures. See Footnote 9 for additional information. c.       Obligations Resulting from Joint and Several Liability Arrangements for Which the Total Amount of the Obligation Is Fixed at the Reporting Date. In February 2013, the FASB issued authoritative guidance within the Codification's Balance Sheet topic that provides guidance on the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date. This authoritative guidance will become effective January 1, 2014. The authoritative guidance will not have a financial or disclosure impact. d.        Presentation of an Unrecognized Tax Benefit. In July 2013, the FASB issued authoritative guidance within the Codification's Income Statement topic that provides guidance on the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exist. The authoritative guidance was issued to eliminate diversity in practice by providing guidance on the presentation of unrecognized tax benefits. This authoritative guidance will become effective January 1, 2014. The authoritative guidance will not have a financial statement or disclosure impact, unless MGE Energy or its subsidiaries are in a net operating loss position.falsefalsefalsenonnum:textBlockItemTypenaThe entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 01 -Paragraph b -Subparagraph 6 -Article 10 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 45 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=6372559&loc=d3e765-108305 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6372559&loc=d3e725-108305 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22499-107794 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22580-107794 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accounting Change -URI http://asc.fasb.org/extlink&oid=6503790 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Direct Effects of a Change in Accounting Principle -URI http://asc.fasb.org/extlink&oid=6510796 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Indirect Effects of a Change in Accounting Principle -URI http://asc.fasb.org/extlink&oid=6515603 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Change in Accounting Principle -URI http://asc.fasb.org/extlink&oid=6507316 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.10-01.(b)(6)) -URI http://asc.fasb.org/extlink&oid=6958853&loc=d3e46468-122699 Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22583-107794 Reference 12: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Retrospective Application -URI http://asc.fasb.org/extlink&oid=6523989 false0New Accounting Pronouncements DisclosurefalseNew Accounting PronouncementsUnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.mgeenergy.com/role/DisclosureNewAccountingPronouncements12