Capital Stock and Stock-Based Awards (Details) - Schedule of Intrinsic value of stock options exercised, pretax stock-based compensation cost and related tax benefits - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total intrinsic value of stock options exercised	$ 5.0	$ 11.0	$ 14.6
Stock-based compensation cost (pretax)	10.7	10.1	9.7
Tax benefits related to stock-based compensation cost	$ (0.2)	$ 0.8	$ 1.8
Weighted average grant date fair value per option (in Dollars per share)	$ 10.45	$ 12.70	$ 14.78