Represents deferred expenses related to rate cases.

No definition available.

Name:	ede_DeferredExpensesRelatedToRateCases
Namespace Prefix:	ede_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the estimated increase in net transmission cost in the next fiscal year as a result of SPP's allocation methodology.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of funding by individual constructing zones.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of funding by region for transmission projects.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of generation needed for next day throughout SPP territory that will be cleared through Integrated Marketplace.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Represents the capacity of transmission projects funded by the region.

+ References

No definition available.

+ Details

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

- Details

Name:	ede_RegulatoryReviewCompetitionActivitiesAxis=ede_SPPRegionalTransmissionDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ede_TransmissionProjectFundingAxis=ede_TransmissionProjectsBetween100KVAnd299KVMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ede_ElectricMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ede_TransmissionProjectFundingAxis=ede_TransmissionProjects300KVOrLargerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ede_TransmissionProjectFundingAxis=ede_TransmissionProjectsUnder100KVMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ede_RegulatoryReviewCompetitionActivitiesAxis=ede_SPPDayAheadMarketMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

REGULATORY MATTERS (Details 3) $ in Millions	1 Months Ended	12 Months Ended
REGULATORY MATTERS (Details 3) $ in Millions	Oct. 31, 2012 item	Dec. 31, 2015 USD ($)	Dec. 31, 2010
RATE MATTERS
Deferred expenses related to rate cases		$ 0.4
SPP Regional Transmission Development
RATE MATTERS
Estimated increase in transmission expenses		$ 1.3
SPP Regional Transmission Development \| Low end of range
RATE MATTERS
Transmission Project Voltage (in kV) \| item	161
SPP Regional Transmission Development \| Transmission projects between 100 kV and 299 kV \| Electric
RATE MATTERS
Regional Funding Percentage			33.30%
Zonal Funding Percentage			66.70%
SPP Regional Transmission Development \| Transmission projects 300 kV or above \| Electric
RATE MATTERS
Regional Funding Percentage			100.00%
Zonal Funding Percentage			0.00%
SPP Regional Transmission Development \| Transmission projects below 100 kV \| Electric
RATE MATTERS
Regional Funding Percentage			0.00%
Zonal Funding Percentage			100.00%
SPP Day-Ahead Market \| Low end of range
RATE MATTERS
Percentage of generation needed for next day throughout SPP territory that will be cleared through Integrated Marketplace		90.00%
SPP Day-Ahead Market \| High end of range
RATE MATTERS
Percentage of generation needed for next day throughout SPP territory that will be cleared through Integrated Marketplace		95.00%