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, 2020	May 31, 2019	May 31, 2018
Share-based Payment Arrangement [Abstract]
Total intrinsic value of stock options exercised	$ 0.2	$ 2.1	$ 5.0
Total stock-based compensation cost (pretax)	3.8	8.3	10.7
Tax benefits (shortfalls) related to stock-based compensation cost	$ (0.5)	$ 0.5	$ (0.2)
Weighted average grant date fair value per option (in Dollars per share)	$ 6.99	$ 11.97	$ 10.45