Pension and Postretirement Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	$ 45	$ 0	$ (90)	$ 0
U.S. Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	4	13	12
Interest cost	28	26	85	76
Expected return on plan assets	(57)	(47)	(174)	(139)
Net actuarial (gain) loss	45	0	(90)	0
Settlement (gain) loss	1	0	(8)	0
Net periodic benefit cost (credit)	21	(17)	(174)	(51)
Non-U.S. Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	4	24	9
Interest cost	13	7	36	19
Expected return on plan assets	(23)	(7)	(68)	(22)
Net periodic benefit cost (credit)	(2)	4	(8)	6
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	1
Interest cost	1	2	4	5
Expected return on plan assets	(2)	(3)	(7)	(7)
Amortization of prior service credit	0	0	0	(1)
Net periodic benefit cost (credit)	$ (1)	$ 0	$ (2)	$ (2)