Restructuring - Recorded Restructuring Activities (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ 1	$ 5	$ 4	$ 13
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense		4	3	5
Selling and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense		$ 1		$ 8
Research and Technical Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ 1		$ 1