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Stock Based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended
Aug. 31, 2015
Aug. 31, 2014
Class A Convertible Common Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Common stock, no par value $ 0  
Common stock, shares authorized 400,000,000  
Common stock, conversion basis Each share of Class A Common Stock is convertible into one share of Class B Common Stock.  
Class B Common Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Common stock, no par value $ 0  
Common stock, shares authorized 2,400,000,000  
Stock Incentive Plan 1990 | Class B Common Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Shares available for grant (in shares) 359,000,000  
Stock Incentive Plan 1990 | Employee Stock Option | Class B Common Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock options vesting period (in years) 4 years  
Stock options expiration from the date of grant (in years) 10 years  
Accelerated stock option expense $ 6 $ 4
Unrecognized compensation costs from stock options, net of estimated forfeitures $ 377  
Unrecognized compensation costs from stock options, net of estimated forfeitures, to be recognized as operating overhead expense over a weighted average period (in years) 2 years 8 months 12 days  
Weighted average fair value per share of the options granted (in dollars per share) $ 25.32 $ 16.91
Minimum term of market traded options for estimates of expected volatility (in years) 1 year  
Employee Stock Purchase Plans | Employee Stock | Class B Common Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Employee stock purchase plans, payroll deductions (percent) 10.00%  
Employee stock purchase plan offering period (in months) 6 months  
Shares purchased, price as percentage of lower of the fair market value (percent) 85.00%