Annual report pursuant to Section 13 and 15(d)

Basic and Diluted Earnings Per Share (Narrative) (Details)

v3.5.0.2
Basic and Diluted Earnings Per Share (Narrative) (Details) - USD ($)
shares in Millions, $ in Millions
 12 Months Ended
May 31, 2016
May 31, 2015
May 31, 2014
Jul. 31, 2016
Approved repurchase amount     $ 350.0  
Common stock repurchased and retired $ 107.9 $ 182.4 $ 249.7  
Common Stock [Member]        
Common shares repurchased and retired 2.2 3.9 6.2  
Common stock repurchased and retired $ 0.1  
Subsequent Event [Member]        
Approved repurchase amount       $ 350.0