Restructuring - Recorded Restructuring Activities (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ (10)	$ 2	$ (9)	$ 2
Selling and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	1		1
Research and Development Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ (9)	$ 2	$ (8)	$ 2