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Schedule I - Condensed Parent Company Finanical Statements (Details-Notes 2) | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
MGE Energy [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | $ 28,246,000 | $ 26,735,000 | $ 67,781,000
First Mortgage Bonds [Member] | 7.70%, 2028 Series |  |  |
Dividend Restrictions |  |  |
Debt covenant, allowable amount available for payment of dividends | 465,200,000 |  |
MGE [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | $ 0 | 0 | 45,000,000
Dividend Restrictions |  |  |
Common equity ratio | 0.573 |  |
MGE [Member] | Minimum [Member] |  |  |
Dividend Restrictions |  |  |
Dividend restrictions, common equity ratio | 0.55 |  |
MGE Power Elm Road [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | $ 15,500,000 | 15,500,000 | 12,000,000
MGE Power West Campus [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | 8,000,000 | 6,500,000 | 6,000,000
MGE Transco [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | 4,653,000 | 4,625,000 | 4,669,000
MGEE Transco [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | 93,000 | 60,000 | 112,000
NGV Fueling Services [Member] |  |  |
Dividends from Affiliates [Line Items] |  |  |
Dividends from affiliates | $ 0 | $ 50,000 | $ 0

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- Definition The common equity ratio, calculated on a thirteen month rolling average. + References No definition available. + Details
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Balance Type: | na
Period Type: | instant

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- Definition The minimum common equity ratio required to avoid dividend payment restirctions to the parent company. + References No definition available. + Details
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- Definition The total amount of dividends available under covenant terms + References No definition available. + Details
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Period Type: | duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(b)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
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- Details
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- Details
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