Components of Net Periodic Benefit Cost (Detail) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0
Interest cost	8	8
Expected return on plan assets	(18)	(17)
Total net periodic benefit cost (income)	(10)	(9)
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost	3	3
Expected return on plan assets	(4)	(5)
Total net periodic benefit cost (income)	$ 0	$ (1)