v2.4.0.8
Components of Net Periodic Benefit Cost (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Pension Benefits
       
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 10 $ 10 $ 32 $ 29
Interest cost 9 10 27 30
Expected return on assets (16) (14) (47) (41)
Amortization of:        
Prior service credit (2) (2) (7) (7)
Actuarial loss 8 8 22 24
Settlement loss 0 3 0 3
Total net periodic benefit cost 9 15 27 38
Other Postretirement Benefits
       
Defined Benefit Plan Disclosure [Line Items]        
Service cost            
Interest cost          1
Expected return on assets            
Amortization of:        
Prior service credit (1)    (2) (2)
Actuarial loss            
Settlement loss 0 0 0 0
Total net periodic benefit cost $ (1)    $ (2) $ (1)