Capital Stock and Stock-Based Awards - Schedule of Intrinsic value of stock options exercised, pretax stock-based compensation cost and related tax benefits (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Share-based Payment Arrangement [Abstract]
Total intrinsic value of stock options exercised	$ 5.1	$ 0.1	$ 0.2
Total stock-based compensation cost (pretax)	7.8	6.6	3.8
Tax benefits (shortfalls) related to stock-based compensation cost	$ 2.3	$ (3.7)	$ (0.5)
Weighted average grant date fair value per option (in Dollars per share)	$ 8.04	$ 3.80	$ 6.99