Goodwill and Other Intangibles - Schedule of other intangible assets subject to amortization (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Other intangibles subject to amortization - beginning balance		$ 8.4	$ 10.5
Intangible assets acquired	$ 0.0	0.0
Adjustments	0.0	(0.5)
Amortization expense	(2.0)	(2.2)	$ (3.2)
Foreign currency translation	(0.4)	0.6
Total other intangibles subject to amortization, net of accumulated amortization of $34.3 and $32.3, respectively	6.0	8.4
Total other intangibles not subject to amortization	2.1	2.1
Total other intangibles	8.1	10.5
Accumulated amortization	$ 34.3	$ 32.3