XML 51 R36.htm IDEA: XBRL DOCUMENT
v3.21.2

Summary of Significant Accounting Principles (Details-2) - Columbia Units [Member] $ in Thousands | 9 Months Ended
--- | ---
Sep. 30, 2021 USD ($)
Jointly Owned Utility Plant Interests [Line Items] |
Net book value of property, plant, and equipment | $ 161,600
Impairment of Long-Lived Assets |
Impairment of long-lived assets | $ 0

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

X
- Definition Amount of loss (recovery of loss) related to a plant abandonment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 10.E) -URI http://asc.fasb.org/extlink&oid=122136288&loc=d3e660019-123033 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section 35 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=6500292&loc=d3e45741-110387 + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAmountOfLossRecoveryOnPlantAbandonment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The present value amount of future cost recoveries that are probable and estimable related to plant abandonment's for regulated industries. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section 35 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6500292&loc=d3e45591-110387 + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPresentValueOfRegulatedAssetForPlantAbandonment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=mgee_ColumbiaUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |