Employee Benefit Plans - Net Periodic Defined Benefit Pension and Other Postretirement Benefit Costs (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1	$ 1
Expected return on plan assets	(2)	(3)
Net periodic benefit (credit) cost	(1)	(2)
Pension Benefits [Member] | Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest cost	2	1
Expected return on plan assets	(4)	(3)
Amortization of actuarial loss	1	1
Net periodic benefit (credit) cost	1	$ 1
Postretirement Benefits [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service credit	(1)
Net periodic benefit (credit) cost	$ (1)