Subsequent Event	9 Months Ended
Jun. 30, 2024
Subsequent Events [Abstract]
Subsequent Event	L. Subsequent Event On July 19, 2024, Cabot entered into agreements to purchase certain assets and to license the related technology, which the Company expects to use in its manufacturing of certain products for its Battery Materials product line. Under these agreements, the Company will pay $27 million at closing, which is expected to occur in the first quarter of fiscal 2025.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/855/tableOfContent

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

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