XML 104 R93.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Fair Value of Financial Instruments (Details-1) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Liabilities: |  |  |
Unamortized discount and debt issuance costs, net |  | $ 4,479 | $ 4,535
Carrying Amount [Member] |  |  |
Assets: |  |  |
Cash and cash equivalents |  | 23,481 | 83,102
Liabilities: |  |  |
Short-term debt - commercial paper |  | 0 | 13,000
Long-Term debt | [1] | 547,879 | 502,431
Fair Value [Member] |  |  |
Assets: |  |  |
Cash and cash equivalents |  | 23,481 | 83,102
Liabilities: |  |  |
Short-term debt - commercial paper |  | 0 | 13,000
Long-Term debt | [1] | 611,909 | 518,811
MGE [Member] | Fair Value Disclosure Item Amounts [Domain] |  |  |
Liabilities: |  |  |
Unamortized discount and debt issuance costs, net |  | 4,479 | 4,535
MGE [Member] | Carrying Amount [Member] |  |  |
Assets: |  |  |
Cash and cash equivalents |  | 3,196 | 4,843
Liabilities: |  |  |
Short-term debt - commercial paper |  | 0 | 13,000
Long-Term debt | [1] | 547,879 | 502,431
MGE [Member] | Fair Value [Member] |  |  |
Assets: |  |  |
Cash and cash equivalents |  | 3,196 | 4,843
Liabilities: |  |  |
Short-term debt - commercial paper |  | 0 | 13,000
Long-Term debt | [1] | $ 611,909 | $ 518,811
[1] | (a) Includes long-term debt due within one year. Excludes debt issuance costs and unamortized discount of $4.5 million as of December 31, 2019 and 2018.

X
- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents short-term debt commercial paper obligations meeting the definition of a liability which should be reported as of the balance sheet date. + References No definition available. + Details
Name: | mgee_ShortTermDebtCommercialPaperFairValueDisclosure
Namespace Prefix: | mgee_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References No definition available. + Details
Name: | us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of unamortized debt discount (premium) and debt issuance costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
Name: | us-gaap_LongTermDebtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mgee_MgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_FairValueDisclosureItemAmountsDomain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |