Background and Basis of Presentation (Details) number in Millions	Mar. 31, 2017
Number of Metered Customers	2.4

The number of metered customers the entity serves.

No definition available.

Name:	cehe_NumberofMeteredCustomers
Namespace Prefix:	cehe_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant