Name:	mgee_JointlyOwnedUtilityPlantPropertyPlantAndEquipmentAllowanceForFundsUsedDuringConstruction
Namespace Prefix:	mgee_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The portion of jointly owned utility plant costs recorded to property plant and equipment related to capital expenditures.

No definition available.

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Namespace Prefix:	mgee_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. This amount does not include constrcution work in progress. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

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Period Type:	instant

Rate the company is entitled to earn a return on construction work in progress as approved in the current rate case for the year.

No definition available.

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Data Type:	num:percentItemType
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Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

No definition available.

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Period Type:	instant

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Data Type:	xbrli:stringItemType
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The proportionate share of interest (percent) in a jointly owned utility plant.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 10.C)

-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section C

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Data Type:	num:percentItemType
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The component of the allowance for funds used during construction during the period based on an assumed rate of return on equity funds used in financing the construction of regulated assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 835

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6501662&loc=d3e56162-110433

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 835

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6501569&loc=d3e55921-110430

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Data Type:	xbrli:monetaryItemType
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Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction.

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Name:	mgee_ConstructionProjectAxis=mgee_ColumbiaEnvironmentalProjectMember
Namespace Prefix:
Data Type:	na
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Period Type:

Name:	us-gaap_JointlyOwnedUtilityPlantAxis=mgee_ColumbiaUnitsMember
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