Pension and Postretirement Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
United States Pension Plan of US Entity
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4	$ 7	$ 8	$ 15
Interest cost	25	31	50	61
Expected return on plan assets	(46)	(45)	(93)	(90)
Net periodic benefit cost (credit)	(17)	(7)	(35)	(14)
Foreign Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	6	9	13
Interest cost	10	12	20	24
Expected return on plan assets	(13)	(13)	(26)	(26)
Net periodic benefit cost (credit)	1	5	3	11
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	1	1
Interest cost	2	3	3	5
Expected return on plan assets	(2)	(3)	(5)	(6)
Amortization of prior service credit	(1)	(1)	(1)	(1)
Net periodic benefit cost (credit)	$ (1)	$ (1)	$ (2)	$ (1)