Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2025	May 31, 2024	May 31, 2023
Change in allowance for credit losses
Balance, beginning of year	$ 14.1	$ 13.4	$ 17.9
Provision for credit losses	0.2	0.7	2.6
Deductions for accounts written off and other reclassifications	(3.6)		(7.1)
Balance, end of year	$ 10.7	$ 14.1	$ 13.4