v3.3.0.814
Amounts Recognized in Accumulated Comprehensive Income Before Tax (Detail) - USD ($)
$ in Millions
Sep. 30, 2015
Sep. 30, 2014
Pension Benefits    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Net actuarial loss (gain) $ 232 $ 121
Prior service credit (9) (16)
Total 223 105
Other Postretirement Benefits    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Net actuarial loss (gain) (5) (7)
Prior service credit (5) (8)
Total $ (10) $ (15)