Regulatory Accounting (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Unrecognized Amount Of Allowed Equity Return	$ 545
Amount Of Allowed Equity Return Recognized In Period	$ 8	$ 8

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