Annual report pursuant to Section 13 and 15(d)

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

v3.7.0.1
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, 2017
May 31, 2016
May 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested, Beginning balance, Awards 1.8    
Granted, Awards 0.6    
Vested, Awards (0.6)    
Forfeited, Awards (0.2)    
Nonvested, Ending balance, Awards 1.6 1.8  
Nonvested, Beginning balance, Weighted-average grant-date fair value per share $ 37.58    
Granted, Weighted-average grant-date fair value per share 53.76 $ 42.60 $ 36.64
Vested, Weighted-average grant-date fair value per share 35.43    
Forfeited, Weighted-average grant-date fair value per share 42.23    
Nonvested, Ending balance, Weighted-average grant-date fair value per share $ 43.53 $ 37.58  
Nonvested, Weighted-average remaining vesting period (years) 2 years 10 months 24 days    
Nonvested, Aggregate intrinsic value [1] $ 97.2    
[1] Intrinsic value for RSUs is based on the market price of the underlying stock as of May 31, 2017.