Restructuring - Recorded Restructuring Activities (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ 9	$ 1
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	3	$ 1
Selling and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ 6