Revenue Recognition (Details) $ in Millions	Mar. 31, 2018 USD ($)
Revenue Recognition and Deferred Revenue [Abstract]
Revenue, remaining performance obligation	$ 910
Revenue, remaining performance obligation in year one	198
Revenue, remaining performance obligation in year two	220
Revenue, remaining performance obligation in year three and thereafter	$ 180

Amount of transaction price allocated to performance obligation that has not been recognized as revenue in Year One

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue in Year Three and Thereafter

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue in Year Two

+ References

No definition available.

+ Details

Name:	ce_RevenueRemainingPerformanceObligationInYearTwo
Namespace Prefix:	ce_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=84173487&loc=SL51747714-108306

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130556-203045

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant