Name:	ede_AmountOfSO2EmissionPermittedBySO2Allowance
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the expected cost of ultimately required addition of scrubber, baghouse and powder activated carbon injection system if proposed Toxics Rule finalized.

No definition available.

Name:	ede_CarbonInjectionSystemExpectedCost
Namespace Prefix:	ede_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the number of customers who have challenged the entity's exemption from solar requirements.

No definition available.

Name:	ede_ChallengeAgainstExemptionFromSolarRequirementsNumberOfCustomers
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Represents the Company's share in the construction cost of generating facility, excluding AFUDC through the balance sheet date.

No definition available.

Name:	ede_ConstructionCostGeneratingFacilityAmountIncurredToDateExcludingAFUDC
Namespace Prefix:	ede_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ede_EnvironmentalLawsAndRegulationsLineItems
Namespace Prefix:	ede_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents the megawatt-hour of renewable energy per renewable energy certificate that has been delivered into the bulk power grid and "unbundles" the renewable attributes from the associated energy.

No definition available.

Name:	ede_MegawattHourOfRenewableEnergyPerRenewableEnergyCertificate
Namespace Prefix:	ede_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

Represents the minimum emission threshold of CO2e (in metric tons) of power generating and certain other facilities which are required to report Greenhouse Gases to the EPA annually.

No definition available.

Name:	ede_MinimumEmissionThresholdOfCO2eMetricTonsForMandatoryReporting
Namespace Prefix:	ede_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	instant

Represents the minimum percentage of energy purchased through long-term Purchased Power Agreements.

No definition available.

Name:	ede_MinimumPercentageOfEnergyPurchased
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the minimum percentage of retail sales which the company and investor-owned utilities in Missouri are required to generate or purchase electricity from renewable energy sources by 2012 under approved Clean Energy Initiative (Proposition C).

No definition available.

Name:	ede_MinimumPercentageOfRetailSalesToGenerateOrPurchaseElectricityFromRenewableEnergySourcesBy2011
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the minimum percentage of retail sales which the company and investor-owned utilities in Missouri are required to generate or purchase electricity from renewable energy sources by 2021 under approved Clean Energy Initiative (Proposition C).

No definition available.

Name:	ede_MinimumPercentageOfRetailSalesToGenerateOrPurchaseElectricityFromRenewableEnergySourcesBy2021
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the fossil-fueled power plants minimum capacity, which are called by CAIR to reduce emission levels of SO2 and Nox.

No definition available.

Name:	ede_MinimumPowerPlantCapacityCalledToReduceEmissionLevelsOfSO2AndNOx
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of former manufactured plant sites with potential future remediation from the acquisition of the natural gas distribution assets.

No definition available.

Name:	ede_NumberOfFormerManufacturingPlantSitesWithPotentialFutureRemediation
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of options in the new regulation pursuant to the Federal Resource Conservation and Recovery Act (RCRA) governing the management and storage of Coal Combustion Residuals (CCR) proposed by EPA.

No definition available.

Name:	ede_NumberOfOptionsAvailableInEPAProposal
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of phases in which nationwide mercury emissions are expected to be reduced.

No definition available.

Name:	ede_NumberOfPhasesExpectedToReduceNationwideMercuryEmissions
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the approximate amount of renewable energy certificates generated (RECs) each year.

No definition available.

Name:	ede_NumberOfRenewableEnergyCertificatesGeneratedAnnually
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of states in which the power plants are required to reduce emission levels as per CAIR.

No definition available.

Name:	ede_NumberOfStatesFossilFueledPowerPlantsRequiredToReduceEmissionLevels
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of years that the site operating permits are valid under the Federal Clean Air Act (CAA).

No definition available.

Name:	ede_NumberOfYearsSiteOperatingPermitsAreValid
Namespace Prefix:	ede_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the current standard to be followed by states to identify and designate all non-attainment areas until the EPA finalizes the proposed standard.

No definition available.

Name:	ede_OzoneCurrentStandard
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the reconsideration period for ozone standards under CAA 2013.

No definition available.

Name:	ede_OzoneStandardsReconsiderationPeriod
Namespace Prefix:	ede_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of carbon dioxide emissions.

No definition available.

Name:	ede_PercentageOfCarbonDioxideEmissions
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of Kansas retail customer peak capacity required to be sourced from renewable energy sources by 2012 as per renewable portfolio standard (RPS).

No definition available.

Name:	ede_PercentageOfKansasRetailCustomerPeakCapacityFromRenewableEnergySourcesBy2012
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of Kansas retail customer peak capacity required to be sourced from renewable energy by 2016 as per renewable portfolio standard (RPS).

No definition available.

Name:	ede_PercentageOfKansasRetailCustomerPeakCapacityFromRenewableEnergySourcesBy2016
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of Kansas retail customer peak capacity required to be sourced from renewable energy sources by 2020 as per renewable portfolio stand (RPS).

No definition available.

Name:	ede_PercentageOfKansasRetailCustomerPeakCapacityFromRenewableEnergySourcesBy2020
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the reduction percentage of NOx from 2005 levels by 2014, required as proposed by CSAPR.

No definition available.

Name:	ede_PercentageOfNOxReductionRequiredAsPerProposedRuleFrom2005LevelsBy2014
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of ownership in a coal ash impoundment at a generating facility.

No definition available.

Name:	ede_PercentageOfOwnershipInCoalAshImpoundmentAtGeneratingFacility
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the reduction percentage of SO2 from 2005 levels by 2014, required as per the proposed Clean Air Transport Rule (CATR).

No definition available.

Name:	ede_PercentageOfSO2ReductionRequiredAsPerProposedRuleFrom2005LevelsBy2014
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of Missouri retail sales required to generate or purchase electricity from solar energy.

No definition available.

Name:	ede_PercentRequirementToGenerateOrPurchaseElectricityFromSolarEnergy
Namespace Prefix:	ede_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The period over which states can give facilities to comply with proposed emissions standards in years.

No definition available.

Name:	ede_PeriodOverWhichStatesCanAllowFacilitiesToComplyWithProposedStandards
Namespace Prefix:	ede_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The amount of time over which newly proposed emissions standards will be phased in.

No definition available.

Name:	ede_PhaseInPeriodForProposedStandards
Namespace Prefix:	ede_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the potential cost to be incurred for construction of new landfill and conversion of existing ash handling from wet to dry system(s), for the compliance of the proposed regulation pursuant to Federal Resource Conversation and Recovery Act (RCRA) governing the management and storage of Coal Combustion Residuals (CCR).

No definition available.

Name:	ede_PotentialCostForConstructionOfNewLandfillAndConversionOfAshHandlingSystemFromWetToDry
Namespace Prefix:	ede_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the primary standard (NAAQS), which proposed to be lowered for ozone designed to protect public health.

No definition available.

Name:	ede_ProposedOzonePrimaryStandard
Namespace Prefix:	ede_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Represents the quantity carbon dioxide emissions limit per megawatt hour.

No definition available.

Name:	ede_QuantityOfCarbonDioxideEmissionsLimit
Namespace Prefix:	ede_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

Represents the SO2 allowances per ton that must be utilized for Missouri units.

No definition available.

Name:	ede_RatioOfSO2AllowancesMustBeUtilized
Namespace Prefix:	ede_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

Represents the period of average carbon dioxide emissions required under The new source performance standards (NSPS).

No definition available.

Name:	ede_RequiredPeriodOfAverageCarbonDioxideEmissions
Namespace Prefix:	ede_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The aggregate costs related to construction and development services during the reporting period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Name:	us-gaap_ConstructionAndDevelopmentCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 96-1

-Paragraph 170

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 96-1

-Paragraph 147, 148, 149, 150

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 90-8

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 30

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13296-110859

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 2

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.