Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans (Details 3)

v2.4.0.6
Stock-Based Compensation Plans (Details 3) (Employee Stock Option [Member], USD $)
In Millions, unless otherwise specified
12 Months Ended
May 31, 2012
May 31, 2011
May 31, 2010
Employee Stock Option [Member]
     
Stock based compensation, stock option plan other information      
Total intrinsic value of stock options exercised $ 0.8 $ 1.9 $ 1.4
Total grant date fair value of stock options vested $ 10.4 $ 20.0 $ 19.0