SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 2) (USD $)	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Municipal Franchise Taxes
Municipal franchise taxes	$ 11,000,000	$ 10,600,000	$ 10,200,000
Property, Plant and Equipment
Period for refund of pro rata amount of the original cost of the extension to developers (in years)	5
Liability for refund of pro rata amount of the original cost of the extension to developers	6,600,000	8,300,000
Property, Plant and Equipment
Accrued cost of removal	128,440,000	88,822,000
Electric \| Cost of removal
Property, Plant and Equipment
Accrued cost of removal	68,600,000	58,800,000
Gas \| Cost of removal
Property, Plant and Equipment
Accrued cost of removal	$ 5,000,000	$ 3,900,000

Represents the amount as of the balance sheet date of refunds owed to developers for the pro rat amount of the original cost of extensions to utility property.

No definition available.

+ Details

Name:	ede_LiabilityForRefundOfProRataAmountOfOriginalCostOfExtensionToDevelopers
Namespace Prefix:	ede_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the period for refund of pro rata amount of the original cost of the extension to developers.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of municipal franchise taxes which are collected for and remitted to their respective entities and are recognized both as operating revenues and offset as operating expenses.

+ References

No definition available.

+ Details

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

- Details

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

- Details

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

- Details

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

- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 71

-Paragraph 11

-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.

+ Details

Name:	us-gaap_RegulatoryLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant