Quarterly report pursuant to Section 13 or 15(d)

Basic and Diluted Earnings Per Share (Details Textual)

v2.4.0.8
Basic and Diluted Earnings Per Share (Details Textual) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Aug. 31, 2014
Aug. 31, 2013
Aug. 31, 2013
Share Repurchase Program 1 [Member]
Aug. 31, 2014
Share Repurchase Program 2 [Member]
May 31, 2014
Share Repurchase Program 2 [Member]
Equity, Class of Treasury Stock [Line Items]          
Stock repurchased and retired during period, Shares     2.1 0.9  
Stock repurchased and retired during period, Value     $ 83.9 $ 37.5  
Stock repurchase program, Authorized amount         $ 350
Common stock issued in connection with the exercise or vesting of stock-based awards 0.7 1.9