Income Taxes - Provision for income tax (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2025	May 31, 2024	May 31, 2023
Current:
Federal	$ 20.7	$ 21.0	$ 25.9
State	3.1	4.0	2.9
Foreign	8.1	7.5	4.8
Total current	31.9	32.5	33.6
Deferred	(5.5)	(20.5)	(2.2)
Provision for income tax	$ 26.4	$ 12.0	$ 31.4