v3.3.0.814
Change in Projected Benefit Obligation/Accumulated Postretirement Benefit Obligation (Detail) - USD ($)
$ in Millions
12 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2013
Recognized in Consolidated Balance Sheets:      
Noncurrent asset $ (36) $ (164)  
Pension Benefits      
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Benefit obligation-beginning of fiscal year 983 897  
Service cost 47 46 $ 43
Interest cost 40 42 35
Actuarial (gain) loss 40 84  
Benefit payments (105) (83)  
Plan amendment 0 (3)  
Benefit obligation-end of fiscal year 1,005 983 897
Accumulated benefit obligation 994 977  
Change in Plan Assets:      
Fair value of plan assets-beginning of fiscal year 1,117 1,055  
Actual return on plan assets (6) 135  
Company contribution 16 10  
Benefit payments (105) (83)  
Fair value of plan assets-end of fiscal year 1,022 1,117 1,055
Funded status at end of fiscal year 17 134  
Recognized in Consolidated Balance Sheets:      
Noncurrent asset (36) (164)  
Current liability (9) (7)  
Noncurrent liability (10) (23)  
Funded status at end of fiscal year 17 134  
Other Postretirement Benefits      
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Benefit obligation-beginning of fiscal year 20 25  
Service cost 0 0 0
Interest cost 1 1 1
Actuarial (gain) loss 0 (2)  
Benefit payments (3) (4)  
Plan amendment 0 0  
Benefit obligation-end of fiscal year 18 20 25
Change in Plan Assets:      
Fair value of plan assets-beginning of fiscal year 0 0  
Actual return on plan assets 0 0  
Company contribution 3 4  
Benefit payments (3) (4)  
Fair value of plan assets-end of fiscal year 0 0 $ 0
Funded status at end of fiscal year (18) (20)  
Recognized in Consolidated Balance Sheets:      
Noncurrent asset 0 0  
Current liability (3) (3)  
Noncurrent liability (15) (17)  
Funded status at end of fiscal year $ (18) $ (20)