Regulatory Accounting (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Unrecognized Amount Of Allowed Equity Return	$ 563		$ 563
Amount Of Allowed Equity Return Recognized In Period	$ 16	$ 7	$ 37	$ 15

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