Goodwill and Intangible Assets - Schedule of Goodwill Balances (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2020 USD ($)
Goodwill And Intangible Assets [Line Items]
Beginning balance	$ 134
Foreign currency impact	8
Ending balance	142
Reinforcement Materials [Member]
Goodwill And Intangible Assets [Line Items]
Beginning balance	46
Foreign currency impact	4
Ending balance	50
Performance Chemicals [Member]
Goodwill And Intangible Assets [Line Items]
Beginning balance	88
Foreign currency impact	4
Ending balance	$ 92