Summary of Accounting Policies (Investments in Affiliates Narrative) (Details)	12 Months Ended
Dec. 31, 2011
Accounting Policies [Abstract]
Certain investments, ownership percentage greater than, accounted for as cost investment	20.00%
Subsidiary reporting period lag	one quarter

Certain investments, ownership percentage greater than, accounted for as cost investment.

No definition available.

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