v2.4.0.6
Common Stock and Stock Based Compensation - Additional Information (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
 12 Months Ended
May 31, 2012
Year
May 31, 2011
May 31, 2010
Common Class A
      
Common Stock and Share Based Compensation [Line Items]      
Common Stock, number of shares authorized (in shares) 175    
Common stock conversion Each share of Class A Common Stock is convertible into one share of Class B Common Stock.    
Common Class B
      
Common Stock and Share Based Compensation [Line Items]      
Common Stock, number of shares authorized (in shares) 750    
Common Class B | Stock Incentive Plan 1990
      
Common Stock and Share Based Compensation [Line Items]      
Shares available for grant (in shares) 163    
Stock options vesting period (in years) 4 years    
Stock options expiration from the date of grant (in years) 10 years    
Unrecognized compensation costs from stock options, net of estimated forfeitures $ 151    
Unrecognized compensation costs from stock options, net of estimated forfeitures, to be recognized as operating overhead expense over a weighted average period (in years) 2.2    
Weighted average fair value per share of the options granted (in dollars per share) $ 22.15 $ 17.68 $ 23.43
Weighted average remaining contractual life for options outstanding (in years) 6.3    
Weighted average remaining contractual life for options exercisable (in years) 4.6    
Aggregate intrinsic value for options outstanding 1,512    
Aggregate intrinsic value for options exercisable 1,008    
Total intrinsic value of options exercised 453 267 239
Common Class B | Stock Incentive Plan 1990 | Restricted Stock
      
Common Stock and Share Based Compensation [Line Items]      
Restricted and unrestricted stock granted to key employees under 1990 Plan, number of shares (in shares) 0.4 0.2 0.5
Restricted stock granted to key employees under 1990 Plan, weighted average values per share (in dollars per shares) $ 98.99 $ 70.23 $ 53.16
Restricted stock vested, fair value $ 22 $ 15 $ 8
Common Class B | Employee Stock
      
Common Stock and Share Based Compensation [Line Items]      
Employee stock purchase plans, payroll deductions 10.00%    
Shares purchased, price as percentage of lower of the fair market value 85.00%    
Purchase of shares by employee (in shares) 0.8 0.8 0.8