Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
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, 2018
May 31, 2017
May 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Nonvested, Beginning balance, Awards 1.6    
Granted, Awards 0.6    
Vested, Awards (1.0)    
Forfeited, Awards (0.1)    
Nonvested, Ending balance, Awards 1.1 1.6  
Nonvested, Beginning balance, Weighted-average grant-date fair value per share $ 43.53    
Granted, Weighted-average grant-date fair value per share 51.15 $ 53.76 $ 42.60
Vested, Weighted-average grant-date fair value per share 42.12    
Forfeited, Weighted-average grant-date fair value per share 46.27    
Nonvested, Ending balance, Weighted-average grant-date fair value per share $ 48.79 $ 43.53  
Nonvested, Weighted-average remaining vesting period (years) 3 years 2 months 12 days    
Nonvested, Aggregate intrinsic value [1] $ 69.2    
[1] Intrinsic value for RSUs is based on the market price of the underlying stock as of May 31, 2018.