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v3.3.1.900

Notes Payable to Banks, Commercial Paper, and Lines of Credit (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Short-term Debt [Line Items] |  |  |  |
Short-term debt outstanding | [1] | $ 0 | $ 7,000 | $ 0
Weighted-average interest rate | [1] | 0.00% | 0.20% | 0.00%
Maximum short-term borrowings | [1] | $ 17,500 | $ 9,000 | $ 32,000
Average short-term borrowings | [1] | $ 1,511 | $ 182 | $ 6,992
Weighted-average interest rate during the year | [1] | 0.17% | 0.24% | 0.18%
Line of Credit [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Available lines of credit | [1] | $ 150,000 | $ 150,000 | $ 150,000
MGE [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Short-term debt outstanding |  | $ 0 | $ 7,000 | $ 0
Weighted-average interest rate |  | 0.00% | 0.20% | 0.00%
Maximum short-term borrowings |  | $ 17,500 | $ 9,000 | $ 32,000
Average short-term borrowings |  | $ 1,511 | $ 182 | $ 6,992
Weighted-average interest rate during the year |  | 0.17% | 0.24% | 0.18%
MGE [Member] | Line of Credit [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Available lines of credit |  | $ 100,000 | $ 100,000 | $ 100,000
MGE [Member] | Line of Credit [Member] | MGE unsecured committed revolving lines of credit totaling $100 million |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Available lines of credit |  | 100,000 |  |
Line of credit, borrowings outstanding |  | $ 0 |  |
Debt covenant, required parent company ownership of MGE |  | 100.00% |  |
MGE [Member] | Line of Credit [Member] | MGE unsecured committed revolving lines of credit totaling $100 million | Minimum [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Debt covenant, ownership interest by outside party resulting in repurchase of notes at par value |  | 30.00% |  |
MGE [Member] | Line of Credit [Member] | MGE unsecured committed revolving lines of credit totaling $100 million | Maximum [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Debt to total capitalization ratio |  | 0.65 |  |
MGE Energy [Member] | Line of Credit [Member] | MGE Energy unsecured committed revolving line of credit totaling $50 million |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Available lines of credit |  | $ 50,000 |  |
Line of credit, borrowings outstanding |  | $ 0 |  |
Debt covenant, required parent company ownership of MGE |  | 100.00% |  |
MGE Energy [Member] | Line of Credit [Member] | MGE Energy unsecured committed revolving line of credit totaling $50 million | Minimum [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Debt covenant, ownership interest by outside party resulting in repurchase of notes at par value |  | 30.00% |  |
MGE Energy [Member] | Line of Credit [Member] | MGE Energy unsecured committed revolving line of credit totaling $50 million | Maximum [Member] |  |  |  |
Short-term Debt [Line Items] |  |  |  |
Debt to total capitalization ratio |  | 0.65 |  |
[1] | MGE Energy short-term borrowings include MGE Energy and MGE lines of credit and MGE commercial paper.

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- Definition Disallowable percent ownership of trading stock by an outside party that would result in repurchase of notes at par value. + References No definition available. + Details
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- Definition Required parent company percent ownership of subsidiary outstanding voting equity interest. Failure to maintain this percentage ownership would result in repurchase of notes at par value. + References No definition available. + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
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