Acquisitions - Schedule of Allocation of Purchase Price Based on Estimates of Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions	Sep. 30, 2021	[1]	Sep. 30, 2020	[1]	Apr. 01, 2020
Assets
Cash					$ 1
Accounts Receivable					8
Inventories					4
Prepaid expenses and other current assets					2
Property, plant and equipment					38
Intangible assets					15
Goodwill	$ 140		$ 134		45
Deferred tax asset					1
Other assets					2
Total assets acquired					116
Liabilities
Accounts payable and accrued liabilities					(12)
Long-term debt					(13)
Other liabilities					(6)
Total liabilities assumed					(31)
Cash consideration paid					$ 85

[1] The balance as of September 30, 2020 and September 30, 2021 includes $444 million of accumulated impairment losses associated with the goodwill of Purification Solutions segment. There were no accumulated impairment losses associated with the goodwill of the Reinforcement Materials or Performance Chemicals segments.