v3.3.0.814
Benefit Obligation and Fair Value of Plan Assets with Obligations in Excess of Plan Assets (Detail) - USD ($)
$ in Millions
Sep. 30, 2015
Sep. 30, 2014
Accumulated benefit obligation in excess of plan assets    
Accumulated benefit obligation, end of year $ (19) $ (30)
Fair value of plan assets, end of year 0 0
Projected benefit obligation in excess of plan assets    
Benefit obligation, end of year (19) (30)
Fair value of plan assets, end of year $ 0 $ 0