Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2022
Income Tax Disclosure [Abstract]
Beginning Balance	$ 1.2	$ 1.2	$ 0.1
Decreases - tax positions taken in prior years	(1.0)	0.0	0.0
Increases - current tax positions	0.0	0.0	1.2
Lapse of statutes of limitations	0.0	0.0	(0.1)
Ending Balance	$ 0.2	$ 1.2	$ 1.2