Employee Benefit Plans - Net Periodic Defined Benefit Pension and Other Postretirement Benefit Costs (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Benefits [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 1	$ 1	$ 1
Interest cost	1	1	3	3
Expected return on plan assets	(3)	(3)	(8)	(8)
Net periodic benefit (credit) cost	(1)	(1)	(4)	(4)
Pension Benefits [Member] | Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	6	7
Interest cost	2	1	6	4
Expected return on plan assets	(4)	(3)	(11)	(10)
Amortization of actuarial loss	1	1	2	4
Net periodic benefit (credit) cost	1	1	3	5
Postretirement Benefits [Member] | U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1	1	1
Amortization of prior service credit	$ (1)	$ (1)	(2)	(2)
Net periodic benefit (credit) cost			$ (1)	$ (1)