Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2022
Change in allowance for credit losses
Balance, beginning of year	$ 13.4	$ 17.9	$ 16.4
Provision for credit losses	0.7	2.6	1.2
Deductions for accounts written off and other reclassifications		(7.1)	0.3
Balance, end of year	$ 14.1	$ 13.4	$ 17.9