Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 9 Months Ended
Feb. 28, 2014
Feb. 28, 2013
Feb. 28, 2014
Feb. 28, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Stock-based compensation expense     $ 131 $ 128
Class B Common Stock | Stock Incentive Plan 1990 [Member]
        
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Stock-based compensation expense 43 45 131 128
Class B Common Stock | Stock Incentive Plan 1990 [Member] | Stock Options
        
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Stock-based compensation expense 32 [1] 32 [1] 93 [1] 90 [1]
Class B Common Stock | Stock Incentive Plan 1990 [Member] | ESPPs
        
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Stock-based compensation expense 5 4 16 14
Class B Common Stock | Stock Incentive Plan 1990 [Member] | Restricted stock
        
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Stock-based compensation expense $ 6 $ 9 $ 22 $ 24
[1] Expense for stock options includes the expense associated with stock appreciation rights. Accelerated stock option expense is recorded for employees eligible for accelerated stock option vesting upon retirement. Accelerated stock option expense for the three month periods ended February 28, 2014 and 2013 was $3 million and $6 million, respectively, and for the nine month periods ended February 28, 2014 and 2013 was $11 million and $16 million, respectively.