Statements Of Cash Flows Parenthetical - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Payments to fund Decommissioning Fund	$ 0.5	$ 1.1

Contribution to decommissioning trust funds for the purchase of investments.

No definition available.

Name:	ee_Contributiontodecommissioningtrustfundforthepurchaseofinvestments
Namespace Prefix:	ee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration