Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

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Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_CreditFacilityAxis=ccmp_SeniorSecuredTermLoanFacilityMember
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DEBT - Narrative (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
DEBT - Narrative (Details) - USD ($) $ in Thousands	Mar. 13, 2020	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Debt Instrument [Line Items]
Proceeds from revolving line of credit		$ 150,000	$ 0
Credit Agreement \| Revolving credit facility \| Term loan facility \| LIBOR Floor
Debt Instrument [Line Items]
Basis spread on variable rate		0.00%
Credit Agreement \| Revolving credit facility \| Term loan facility \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Credit Agreement \| Revolving credit facility \| Term loan facility \| Base rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Credit Agreement \| Revolving credit facility \| Line of credit
Debt Instrument [Line Items]
Proceeds from revolving line of credit	$ 150,000
Available credit remaining		$ 50,000
Credit Agreement \| Senior secured term loan facility \| Term loan facility \| LIBOR Floor
Debt Instrument [Line Items]
Basis spread on variable rate		0.00%
Credit Agreement \| Senior secured term loan facility \| Term loan facility \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		2.00%		2.25%
Credit Agreement \| Senior secured term loan facility \| Term loan facility \| Base rate
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%