Summary of Accounting Policies (Cash and Cash Equivalents Narrative) (Details)	12 Months Ended
Dec. 31, 2011
Accounting Policies [Abstract]
Maturity range of cash and cash equivalents, number of months or less	three

Maturity range of cash and cash equivalents, number of months or less.

No definition available.

Name:	ce_MaturityRangeOfCashAndCashEquivalentsNumberOfMonthsOrLess
Namespace Prefix:	ce_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration