Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans (RSU Activity) (Details)

v3.5.0.2
Stock-Based Compensation Plans (RSU Activity) (Details) - Restricted Stock Units [Member] - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
May 31, 2016
May 31, 2015
May 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested, Beginning balance, Awards 1.8    
Granted, Awards 0.7    
Vested, Awards (0.5)    
Forfeited, Awards (0.2)    
Nonvested, Ending balance, Awards 1.8 1.8  
Nonvested, Beginning balance, Weighted-average grant-date fair value per share $ 33.57    
Granted, Weighted-average grant-date fair value per share 42.60 $ 36.64 $ 36.37
Vested, Weighted-average grant-date fair value per share 31.34    
Forfeited, Weighted-average grant-date fair value per share 35.97    
Nonvested, Ending balance, Weighted-average grant-date fair value per share $ 37.58 $ 33.57  
Nonvested, Weighted-average remaining vesting period (years) 3 years    
Nonvested, Aggregate intrinsic value [1] $ 96.5    
[1] Intrinsic value for RSUs is the market price of the underlying stock as of May 31, 2016.