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No definition available.

Name:	mgee_Definedbenefitplanestimatednetfuturebenefitpaymentsabstract
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The amount of the benefits expected to be paid, net of the prescription drug subsidy receipts expected to be received in the five fiscal years thereafter (the aggregate net amount of benefits expected to be paid in years 6 through 10 after the date of the latest statement of financial position).

No definition available.

Name:	mgee_Definedbenefitplanexpectednetfuturebenefitpaymentsfivefiscalyearsthereafter
Namespace Prefix:	mgee_
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The amount of the benefits expected to be paid, net of the prescription drug subsidy receipts expected to be received in Year 1 after the balance sheet date.

No definition available.

Name:	mgee_Definedbenefitplanexpectednetfuturebenefitpaymentsnexttwelvemonths
Namespace Prefix:	mgee_
Data Type:	xbrli:monetaryItemType
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The amount of the benefits expected to be paid, net of the prescription drug subsidy receipts expected to be received in Year 5 after the balance sheet date.

No definition available.

Name:	mgee_Definedbenefitplanexpectednetfuturebenefitpaymentsyearfive
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The amount of the benefits expected to be paid, net of the prescription drug subsidy receipts expected to be received in Year 4 after the balance sheet date.

No definition available.

Name:	mgee_Definedbenefitplanexpectednetfuturebenefitpaymentsyearfour
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The amount of the benefits expected to be paid, net of the prescription drug subsidy receipts expected to be received in Year 3 after the balance sheet date.

No definition available.

Name:	mgee_Definedbenefitplanexpectednetfuturebenefitpaymentsyearthree
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The amount of the benefits expected to be paid, net of the prescription drug subsidy receipts expected to be received in Year 2 after the balance sheet date.

No definition available.

Name:	mgee_Definedbenefitplanexpectednetfuturebenefitpaymentsyeartwo
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No definition available.

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No definition available.

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsAbstract
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Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Data Type:	xbrli:monetaryItemType
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Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

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Namespace Prefix:	us-gaap_
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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

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Namespace Prefix:	us-gaap_
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Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

No definition available.

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Data Type:	xbrli:stringItemType
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Amount of payment for pension and other postretirement benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3536-108585

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Amount of prescription drug subsidy receipts expected after fifth fiscal year following latest fiscal year.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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Amount of prescription drug subsidy receipts expected in next fiscal year following latest fiscal year.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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Amount of prescription drug subsidy receipts expected in fifth fiscal year following latest fiscal year.

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Amount of prescription drug subsidy receipts expected in fourth fiscal year following latest fiscal year.

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Amount of prescription drug subsidy receipts expected in third fiscal year following latest fiscal year.

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Amount of prescription drug subsidy receipts expected in second fiscal year following latest fiscal year.