Financial Instruments And Investments (Unrealized Holding Losses Included In Pre-Tax Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Financial Instruments And Investments [Abstract]
Gross unrealized holding losses included In pre-tax income	$ (479)	$ (2,116)	$ (263)

Other than Temporary Impairment Losses, Investments, Recognized in Earnings, before Tax, Available-for-sale Securities

No definition available.

Name:	ee_OtherThanTemporaryImpairmentLossesInvestmentsRecognizedInEarningsBeforeTaxAvailableForSaleSecurities
Namespace Prefix:	ee_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration