Summary of Significant Accounting Policies - Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021
Change in allowance for credit losses
Balance, beginning of year	$ 17.9	$ 16.4	$ 22.1
Provision charged to operations, net of recoveries	2.6	1.2	8.5
Deductions for accounts written off and other reclassifications	(7.1)	0.3	(14.2)
Balance, end of year	$ 13.4	$ 17.9	$ 16.4