Statements Of Cash Flows Parenthetical - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Payments to fund Decommissioning Fund	$ 1.6	$ 3.4

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