v3.3.0.814
Share-based Compensation - Additional Information (Detail)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
Mar. 19, 2015
Jan. 28, 2015
shares
Sep. 30, 2015
USD ($)
$ / shares
shares
Sep. 30, 2014
USD ($)
$ / shares
Sep. 30, 2013
USD ($)
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Maximum number of Class A Common Stock authorized for issuance under the 2007 Equity Incentive Compensation Plan ("the "EIP") | shares   20      
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period     10 years    
Share-based compensation expense     $ 184 $ 172 $ 179
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense     54 51 53
Total intrinsic value from options exercised     134 187 176
Tax benefit realized from options exercised     86 65 59
Unrecognized compensation cost     $ 17    
Total unrecognized compensation cost related to non-vested options expected to be recognized over a weighted average period (in years)     1 year 4 months 24 days    
Total fair value of RSAs and RSUs vested     $ 132 $ 126 $ 98
Weighted average remaining contractual term     5 years    
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date   15.00%      
Employee Stock Option          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period from the date of grant     3 years    
Restricted Stock Awards          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Unrecognized compensation cost     $ 138    
Weighted average grant date fair value (in dollars per share) | $ / shares     $ 63.71 $ 49.98 $ 36.80
Weighted average remaining contractual term     1 year 6 months    
Restricted Stock Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Unrecognized compensation cost     $ 38    
Weighted average grant date fair value (in dollars per share) | $ / shares     $ 62.88 $ 49.44 $ 36.55
Weighted average remaining contractual term     1 year 4 months 24 days    
Performance Based Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period from the date of grant     3 years 3 years 3 years
Unrecognized compensation cost     $ 11    
Weighted average grant date fair value per share | $ / shares     $ 69.78 $ 56.37 $ 41.04
Class A common stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Common stock split, conversion ratio 4        
Equity Incentive Compensation Plan, 2007 [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Maximum number of Class A Common Stock authorized for issuance under the 2007 Equity Incentive Compensation Plan ("the "EIP") | shares     236