Goodwill and Other Intangibles - Schedule of other intangible assets subject to amortization (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Nov. 30, 2023	Nov. 30, 2023	Nov. 30, 2022	May 31, 2023
Finite-lived Intangible Assets [Roll Forward]
Beginning balance other intangibles subject to amortization		$ 7.8	$ 6.0	$ 6.0
Additions	$ 5.8	5.8	4.1	4.1
Amortization expense		(1.2)	(1.1)	(2.2)
Foreign currency translation		0.0	(0.1)	(0.1)
Total other intangibles subject to amortization, net of accumulated amortization of $24.8, $24.1 and $22.5, respectively	12.4	12.4	8.9	7.8
Accumulated amortization of intangible assets	37.7	37.7	35.4	36.5
Total other intangibles not subject to amortization	2.1	2.1	2.1	2.1
Total other intangibles	$ 14.5	$ 14.5	$ 11.0	$ 9.9