Quarterly report pursuant to Section 13 or 15(d)

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

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Basic and Diluted Earnings Per Share (Narrative) (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended 6 Months Ended
Nov. 30, 2018
Nov. 30, 2017
Nov. 30, 2018
Nov. 30, 2017
Jul. 31, 2016
Equity, Class of Treasury Stock [Line Items]          
Common stock issued in connection with exercise or vesting of stock-based awards 0.1 0.3 0.6 0.8  
Common stock issued related to acquisition       0.6  
Quarterly dividend per share $ 0.56 $ 0.50 $ 1.12 $ 1.00  
Authorized in July 2016 [Member]          
Equity, Class of Treasury Stock [Line Items]          
Expiration date     May 31, 2019    
Approved repurchase amount         $ 350.0
Common stock repurchased and retired, shares 0.0 0.0 0.5 1.6  
Common stock repurchased and retired, values     $ 32.8 $ 94.1