Commitments and Contingencies (Tables)

12 Months Ended

Sep. 30, 2016

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Commitments under Non-Cancelable Leases

Future minimum rental commitments under non-cancelable leases are as follows:

	(Dollars in millions)
2017	$	21
2018		17
2019		13
2020		8
2021		7
2022 and thereafter		56
Total future minimum rental commitments	$	122

Schedule of Raw Material Purchased under Long Term Purchase Agreements

Cabot has entered into long-term purchase agreements primarily for the purchase of raw materials. Under certain of these agreements, the quantity of material being purchased is fixed, but the price paid changes as market prices change. Raw materials purchased under these agreements by segment for fiscal 2016, 2015 and 2014 are as follows:

	Years Ended September 30
	2016		2015		2014
	(Dollars in millions)
Reinforcement Materials	$	193	$	276	$	354
Performance Chemicals		68		62		43
Purification Solutions		7		14		32
Other		—		—		3
Total	$	268	$	352	$	432

Schedule of Components of Purchase Commitments

The purchase commitments for Reinforcement Materials, Performance Chemicals, and Purification Solutions covered by these agreements are with various suppliers and purchases are expected to take place as follows:

	Payments Due by Fiscal Year
	2017		2018		2019		2020		2021		Thereafter		Total
	(Dollars in millions)
Reinforcement Materials	$	153	$	137	$	134	$	101	$	78	$	1,151	$	1,754
Performance Chemicals		54		39		34		31		29		124		311
Purification Solutions		10		6		4		4		—		—		24
Total	$	217	$	182	$	172	$	136	$	107	$	1,275	$	2,089