Taxes - Schedule of provision for income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2022
Current
Federal	$ 3.4	$ 26.4	$ (2.1)
State and local	1.2	1.6	0.6
Non-United States	1.5	1.6	3.0
Total Current	6.1	29.6	1.5
Deferred Income Taxes and Tax Credits [Abstract]
Federal	0.5	(6.6)	6.1
State and local	(1.3)	3.9	2.4
Non-United States	(1.2)	(1.0)	(1.3)
Total Deferred	(2.0)	(3.7)	7.2
Total provision (benefit) for income taxes	$ 4.1	$ 25.9	$ 8.7