Commitments and Contingencies (Tables)

12 Months Ended

Sep. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

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 2020, 2019 and 2018 are as follows:

	Years Ended September 30
	2020		2019		2018
	(In millions)
Reinforcement Materials	$	198	$	393	$	375
Performance Chemicals		58		65		55
Purification Solutions		2		8		11
Total	$	258	$	466	$	441

Schedule of Components of Purchase Commitments

For these purchase commitments, the amounts included in the table below are based on market prices as of September 30, 2020 which may differ from actual market prices at the time of purchase.

	Payments Due by Fiscal Year
	2021		2022		2023		2024		2025		Thereafter		Total
	(In millions)
Reinforcement Materials	$	115	$	101	$	87	$	86	$	86	$	911	$	1,386
Performance Chemicals		54		53		34		34		35		332	$	542
Total	$	169	$	154	$	121	$	120	$	121	$	1,243	$	1,928