Amounts Recognized in Accumulated Comprehensive Income Before Tax (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
U.S. Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	$ 241	$ 232
Prior service credit	0	(9)
Total	241	223
U.S. Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	(5)	(5)
Prior service credit	(2)	(5)
Total	(7)	$ (10)
Non-U.S. Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial loss (gain)	66
Prior service credit	0
Total	$ 66