Benefit Obligations Benefit Obligations (Narrative) (Details)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Compensation and Retirement Disclosure [Abstract]
Funded status of multiemployer plan percentage	100.00%	100.00%	100.00%
Company Aggregate Multiemployer Benefit Plan Contribution, Less Than, Percentage	5.00%

Company Aggregate Multiemployer Benefit Plan Contribution, LessThan, Percentage.

No definition available.

Name:	ce_CompanyAggregateMultiemployerBenefitPlanContributionLessThanPercentage
Namespace Prefix:	ce_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant