v2.4.0.6
Total Stock-Based Compensation Expense (Parenthetical) (Detail) (USD $)
In Millions, unless otherwise specified
12 Months Ended
May 31, 2012
May 31, 2011
May 31, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]      
Accelerated stock option expense $ 17 $ 12 $ 74