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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_
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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:	num: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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The fuel rules surplus credit that is not required to be refunded to customers and will be amortized. The fuel credit will accrue interest at weighted cost of capital.

+ References

No definition available.

+ Details

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

- Definition

The fuel rules surplus credit that is not required to be refunded to customers and will be amortized during the current period. The fuel credit will accrue interest at weighted cost of capital.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

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

+ Details

Name:	us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate
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Data Type:	num:percentItemType
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Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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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

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Namespace Prefix:	us-gaap_
Data Type:	num: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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PublicUtilitiesRateMattersAbstract
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Data Type:	xbrli:stringItemType
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- 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:	num:percentItemType
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Rate Matters (Details) (PSCW [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
	Mar. 31, 2014 Legal Entity Type of Counterparty [Domain]	Mar. 31, 2014 MGE [Member]	Dec. 31, 2013 MGE [Member]	Mar. 31, 2014 Columbia Environmental Project [Member] MGE [Member]	Dec. 31, 2013 Columbia Environmental Project [Member] MGE [Member]	Mar. 31, 2014 Electric [Member] MGE [Member]	Dec. 31, 2013 Electric [Member] MGE [Member]	Dec. 31, 2015 Electric [Member] Proposed Future Rate Matters [Member] MGE [Member]	Mar. 31, 2014 Gas [Member] MGE [Member]	Dec. 31, 2013 Gas [Member] MGE [Member]	Dec. 31, 2015 Gas [Member] Proposed Future Rate Matters [Member] MGE [Member]
Rate Proceedings [Abstract]
Proposed rate increase (decrease), percentage								2.80%			(2.30%)
Authorized rate increase (decrease), percentage						0.00%	3.80%		0.00%	1.00%
Authorized rate increase (decrease), amount						$ 0	$ 14.9		$ 0	$ 1.6
Authorized AFUDC Rate				100.00%	50.00%
Return of electric fuel credit, total		6.2
Authorized return on equity, percentage		10.30%	10.30%
Fuel Rules [Abstract]
Fuel rules, bandwidth	2.00%
Fuel rules, electric fuel deferred costs upper threshold	102.00%
Fuel rules, electric fuel deferred costs lower threshold	98.00%
Return of electric fuel credit, current period		$ 1.6