LEASES - Narrative (Details) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)
Leases [Abstract]
Weighted average lease term for operating leases	6 years	6 years
Lease cost	$ 2,221	$ 7,027
Operating lease cost	1,868	5,754
Short-term and variable lease costs	$ 353	$ 1,273
Weighted average discount rate for operating leases	3.06%	3.06%

Short-term Lease And Variable Lease, Cost

No definition available.

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Namespace Prefix:	ccmp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

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+ Details

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Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
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-Paragraph 53
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+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Weighted average discount rate for operating lease calculated at point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
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-Paragraph 4
-Subparagraph (g)(4)
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- Definition

Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
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-Subparagraph (g)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

+ Details

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