Regulatory Accounting (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Unrecognized Amount Of Allowed Equity Return	$ 533		$ 533
Amount Of Allowed Equity Return Recognized In Period	$ 12	$ 13	$ 20	$ 21

Amount of allowed equity return on the true-up balance that has not been recognized as it will be recognized as it is recovered in rates.

No definition available.

Name:	cehe_UnrecognizedAmountOfAllowedEquityReturn
Namespace Prefix:	cehe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant