Employee Benefit Plans - Net Periodic Defined Benefit Pension and Other Postretirement Benefit Costs (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1	$ 1
Expected return on plan assets	(2)	(2)
Net periodic benefit (credit) cost	(1)	(1)
Pension Benefits [Member] | Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest cost	2	2
Expected return on plan assets	(4)	(4)
Amortization of actuarial loss	1	1
Settlement and curtailment gain	(6)
Net periodic benefit (credit) cost	$ (5)	1
Postretirement Benefits [Member] | U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service credit		(1)
Net periodic benefit (credit) cost		$ (1)