Statements of Cash Flows Parenthetical - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Payments to fund Decommissioning Fund	$ 2.1	$ 3.8	$ 4.5

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