Subsequent Events	9 Months Ended
Jun. 30, 2012
Subsequent Events	O. Subsequent Events On July 31, 2012, Cabot completed the acquisition of Norit N.V. and its subsidiaries (“Norit”), paying approximately $1.1 billion in cash to purchase all of the issued and outstanding share capital of Norit. The Company has incurred acquisition costs of approximately $5 million through June 30, 2012, which is included in Selling and administrative expenses. Norit will be reported as a stand-alone segment named Purification Solutions. Goodwill generated from the acquisition will not be deductible for tax purposes. Norit develops, manufactures, and sells high-grade activated carbons used in a range of environmental, health, safety and industrial applications. Cabot’s purchase of Norit supports the Company’s ongoing transformation to a higher margin, less cyclical, specialty chemicals and performance materials company. Given the recent date of the acquisition, the Company has not completed the detailed valuation analysis necessary to finalize the associated purchase accounting. As a result, the Company has not provided additional disclosures related to the business combination. On July 12, 2012, Cabot issued $250 million aggregate principal amount of 2.550% Senior Notes due 2018 (the “2018 Notes”) and $350 million aggregate principal amount of 3.700% Senior Notes due 2022 (the “2022 Notes”). The Company will pay interest on the 2018 Notes and 2022 Notes on January 15 and July 15 of each year, beginning January 15, 2013. The Company used the net proceeds from the 2018 and 2022 Notes to finance a portion of the acquisition of Norit. On July 13, 2012, Cabot exercised the expansion option under its Credit Agreement (“Facility”) to effect a $200 million increase in the aggregate commitments available. There were no changes to the terms of the Facility. Following the expansion, aggregate commitments under the Facility equaled $750 million. The Company used the Facility and cash on hand to fund the remaining portion of the acquisition of Norit.

O. Subsequent Events

On July 31, 2012, Cabot completed the acquisition of Norit N.V. and its subsidiaries (“Norit”), paying approximately $1.1 billion in cash to purchase all of the issued and outstanding share capital of Norit. The Company has incurred acquisition costs of approximately $5 million through June 30, 2012, which is included in Selling and administrative expenses. Norit will be reported as a stand-alone segment named Purification Solutions. Goodwill generated from the acquisition will not be deductible for tax purposes.

Norit develops, manufactures, and sells high-grade activated carbons used in a range of environmental, health, safety and industrial applications. Cabot’s purchase of Norit supports the Company’s ongoing transformation to a higher margin, less cyclical, specialty chemicals and performance materials company.

Given the recent date of the acquisition, the Company has not completed the detailed valuation analysis necessary to finalize the associated purchase accounting. As a result, the Company has not provided additional disclosures related to the business combination.

On July 12, 2012, Cabot issued $250 million aggregate principal amount of 2.550% Senior Notes due 2018 (the “2018 Notes”) and $350 million aggregate principal amount of 3.700% Senior Notes due 2022 (the “2022 Notes”). The Company will pay interest on the 2018 Notes and 2022 Notes on January 15 and July 15 of each year, beginning January 15, 2013. The Company used the net proceeds from the 2018 and 2022 Notes to finance a portion of the acquisition of Norit.

On July 13, 2012, Cabot exercised the expansion option under its Credit Agreement (“Facility”) to effect a $200 million increase in the aggregate commitments available. There were no changes to the terms of the Facility. Following the expansion, aggregate commitments under the Facility equaled $750 million. The Company used the Facility and cash on hand to fund the remaining portion of the acquisition of Norit.