Leases - Lease Expense (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Leases [Abstract]
Operating lease expense	$ 25.9	$ 28.3	$ 28.6
Depreciation of leased assets	2.2	2.3	2.1
Accretion of lease liabilities	0.4	0.4	0.4
Total lease expense	$ 28.5	$ 31.0	$ 31.1