XML 29 R70.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Notes Payable to Banks, Commercial Paper, and Lines of Credit (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Short-term Debt [Line Items] |  |  |  |  |  |
Maximum short-term borrowings | $ 32,000,000 | [1] | $ 16,000,000 | [1] | $ 28,500,000 | [1]
Average short-term borrowings | 6,992,000 | [1] | 1,154,000 | [1] | 3,410,000 | [1]
Weighted-average interest rate during the year | 0.18% | [1] | 0.17% | [1] | 1.43% | [1]
Line of Credit [Member] |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Available lines of credit | 150,000,000 | [1] | 115,000,000 | [1] | 115,000,000 | [1]
MGE [Member] |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Maximum short-term borrowings | 32,000,000 |  | 16,000,000 |  | 9,500,000 |
Average short-term borrowings | 6,992,000 |  | 1,154,000 |  | 349,000 |
Weighted-average interest rate during the year | 0.18% |  | 0.17% |  | 0.25% |
MGE [Member] | Line of Credit [Member] |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Available lines of credit | 100,000,000 |  | 75,000,000 |  | 75,000,000 |
MGE [Member] | Line of Credit [Member] | MGE $100 million unsecured committed revolving line of credit |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Available lines of credit | 100,000,000 |  |  |  |  |
Line of credit, borrowings outstanding | 0 |  |  |  |  |
Debt covenant, required parent company ownership of MGE | 100.00% |  |  |  |  |
MGE [Member] | Line of Credit [Member] | MGE $100 million unsecured committed revolving line of credit | 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 $100 million unsecured committed revolving line of credit | Maximum [Member] |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Debt to total capitalization ratio | 0.65 |  |  |  |  |
MGE Energy [Member] | Line of Credit [Member] | MGE Energy $50 million unsecured commiteed revolving line of credit |  |  |  |  |  |
Short-term Debt [Line Items] |  |  |  |  |  |
Available lines of credit | 50,000,000 |  |  |  |  |
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 $50 million unsecured commiteed revolving line of credit | 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 $50 million unsecured commiteed revolving line of credit | 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.

X
- 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
Name: | mgee_DebtInstrumentCovenantTermsOwnershipInterestByOutsidePartyResultingInRepurchaseOfNotesAtParValue
Namespace Prefix: | mgee_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- 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
Name: | mgee_DebtInstrumentCovenantTermsRequiredParentCompanyOwnershipOfOutstandingVotingEquityInterestInSubsidiary
Namespace Prefix: | mgee_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Reflects the calculation of the average interest rate weighted by the amount of short-term debt outstanding by type or by instrument during the period. + References No definition available. + Details
Name: | mgee_ShortTermDebtWeightedAverageInterestRateDuringPeriod
Namespace Prefix: | mgee_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount borrowed under the credit facility as of the balance sheet date. + References 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 + Details
Name: | us-gaap_LineOfCreditFacilityAmountOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition 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. + References Reference 1: 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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Indebtedness divided by net capital. + References No definition available. + Details
Name: | us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period. + References No definition available. + Details
Name: | us-gaap_ShorttermDebtAverageOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_ShortTermDebtLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, the maximum amount borrowed at any time during the period. + References No definition available. + Details
Name: | us-gaap_ShorttermDebtMaximumAmountOutstandingDuringPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration