- Definition

The amount of electric fuel rules monitored costs which have been deferred outside the symmetrical cost tolerance band authorized by a regulatory agency.

+ References

No definition available.

+ Details

Name:	mgee_Deferredfuelrulesmonitoredcosts
Namespace Prefix:	mgee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financial statement tax effects of the Tax Cuts and Jobs Act.

+ References

No definition available.

+ Details

Name:	mgee_EffectsOfTheTaxCutsAndJobsActAbstract
Namespace Prefix:	mgee_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	mgee_FuelRulesAbstract
Namespace Prefix:	mgee_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Pursuant to the provisions of the rate order, the fuel rules bandwidth will be plus or minus this percentage.

+ References

No definition available.

+ Details

Name:	mgee_FuelRulesBandwidth
Namespace Prefix:	mgee_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Under fuel rules, the amount in which MGE is required to defer the benefit of lower costs if actual electric fuel costs were less than the allowed electric fuel costs in latest rate order.

+ References

No definition available.

+ Details

Name:	mgee_FuelRulesElectricFuelDeferredCostsLowerThreshold
Namespace Prefix:	mgee_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Under fuel rules, the amount in which MGE would defer if actual electric fuel costs exceeded allowed electric fuel costs in latest rate order.

+ References

No definition available.

+ Details

Name:	mgee_FuelRulesElectricFuelDeferredCostsUpperThreshold
Namespace Prefix:	mgee_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of electric fuel-related savings that has been returned in customer bill credits.

+ References

No definition available.

+ Details

Name:	mgee_PublicUtilitiesReturnOfFuelRulesCredit
Namespace Prefix:	mgee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of excess deferred taxes related to the Tax Cuts and Jobs Act not governed by IRS normalization rules to be factored in rates.

+ References

No definition available.

+ Details

Name:	mgee_PublicUtilitiesReturnOfTaxCutsAndJobsActUnprotectedExcessDeferredTaxes
Namespace Prefix:	mgee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's approved equity to capital, including debt and equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRateMattersAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of public utility's requested equity to capital, including debt and equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedEquityCapitalStructurePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAgencyAxis=mgee_PublicServiceCommissionOfWisconsinMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=mgee_MgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	mgee_FuelRulesCreditYearAxis=mgee_FuelRulesRefund2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=mgee_ElectricRateProceedingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=mgee_GasRateProceedingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Rate Matters (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
Rate Matters (Details) - USD ($) $ in Thousands	Oct. 31, 2021	Sep. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fuel Rules [Abstract]
Deferred fuel rules monitored costs		$ 0					$ 1,500
Rate Matters For Future Periods [Member] \| Subsequent Event [Member]
Rate Proceedings [Abstract]
Proposed return on equity, percentage				9.80%
Proposed equity capital structure, percentage				55.60%
PSCW [Member] \| MGE [Member]
Rate Proceedings [Abstract]
Authorized return on equity, percentage		9.80%				9.80%	9.80%
Approved equity capital structure, percentage		55.80%				56.10%	56.60%
Fuel Rules [Abstract]
Fuel rules, bandwidth		1.00%				2.00%
Fuel rules, electric fuel deferred costs upper threshold		101.00%
Fuel rules, electric fuel deferred costs lower threshold		99.00%
PSCW [Member] \| MGE [Member] \| Fuel Rules Refund, 2020 [Member] \| Subsequent Event [Member]
Fuel Rules [Abstract]
Return of electric fuel credit, total	$ 3,200
Electric Rate Proceeding [Member] \| Rate Matters For Future Periods [Member] \| Subsequent Event [Member]
Rate Proceedings [Abstract]
Proposed rate increase (decrease), percentage				5.16%
Electric Rate Proceeding [Member] \| PSCW [Member] \| MGE [Member]
Rate Proceedings [Abstract]
Authorized rate increase (decrease), percentage		0.00%				(0.84%)	(2.24%)
Authorized rate increase (decrease), amount						$ (3,400)	$ (9,200)
Electric Rate Proceeding [Member] \| PSCW [Member] \| Rate Matters For Future Periods [Member] \| MGE [Member]
Effects Of The Tax Cuts And Jobs Act [Abstract]
Return of unprotected excess deferred taxes					$ 18,200
Gas Rate Proceeding [Member] \| Rate Matters For Future Periods [Member] \| Subsequent Event [Member]
Rate Proceedings [Abstract]
Proposed rate increase (decrease), percentage			0.96%	2.15%
Gas Rate Proceeding [Member] \| PSCW [Member] \| MGE [Member]
Rate Proceedings [Abstract]
Authorized rate increase (decrease), percentage		4.00%				1.46%	1.06%
Authorized rate increase (decrease), amount						$ 2,400	$ 1,700