Subsequent Events - Additional Information (Detail) - Subsequent Events [Member]	Aug. 06, 2021 USD ($) Option	Jul. 31, 2021 USD ($)
Revolving Credit Facility, expires fiscal 2023 [Member]
Subsequent Event [Line Items]
Revolving credit facility, borrowing capacity		$ 1,000,000,000
Debt instrument, maturity date		Oct. 23, 2022
Revolving Credit Facility, expires fiscal 2026 [Member]
Subsequent Event [Line Items]
Revolving credit facility, borrowing capacity	$ 1,000,000,000
Debt instrument, maturity date	Aug. 06, 2026
Revolving credit facility, number of options to extend \| Option	2
Revolving credit facility, options extension period	1 year
Revolving credit facility, cap amount used to calculate net debt	$ 150,000,000
Maximum [Member] \| Revolving Credit Facility, expires fiscal 2026 [Member]
Subsequent Event [Line Items]
Debt instrument, covenant, ratio of consolidated total debt to consolidated EBITDA	3.50%
Flood [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Estimated charge for damages		$ 10,000,000
Flood [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Estimated charge for damages		$ 15,000,000

Debt instrument, covenant, ratio of consolidated total debt to consolidated EBITDA

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

Line of credit cap amount used to calculate net debt.

+ References

No definition available.

+ Details

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Namespace Prefix:	cbt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line of credit facility number of options to extend.

+ References

No definition available.

+ Details

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Namespace Prefix:	cbt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility options extension period.

+ References

No definition available.

+ Details

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Namespace Prefix:	cbt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ 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:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248

+ Details

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

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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