Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current year actuarial loss (gain)	$ 106	$ 122	$ 27
Amortization of prior service credit/(cost)	(10)	1	$ 8
U.S. Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current year actuarial loss (gain)	30	119
Amortization of actuarial (loss) gain	(20)	(8)
Current year prior service credit	0	0
Amortization of prior service credit/(cost)	9	7
Total recognized in other comprehensive income	19	118
Total recognized in net periodic benefit cost and other comprehensive income	14	134
U.S. Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current year actuarial loss (gain)	(2)	0
Amortization of actuarial (loss) gain	2	2
Current year prior service credit	0	0
Amortization of prior service credit/(cost)	3	3
Total recognized in other comprehensive income	3	5
Total recognized in net periodic benefit cost and other comprehensive income	(1)	$ 1
Non-U.S. Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current year actuarial loss (gain)	66
Amortization of actuarial (loss) gain	0
Current year prior service credit	0
Amortization of prior service credit/(cost)	0
Total recognized in other comprehensive income	66
Total recognized in net periodic benefit cost and other comprehensive income	$ 66