Business Segment Information - Reconciliation of Gross Profit to Income (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2022	Aug. 31, 2021
Reconciliation of segment gross profit to income from continuing operations before provision for income taxes
Segment gross profit	$ 81.9	$ 64.6
Selling, general, and administrative	(50.1)	(49.3)
Loss from joint ventures	(0.6)	(0.2)
Other income, net	0.2	0.7
Interest expense	(1.1)	(0.7)
Interest income	0.1
Income from continuing operations before provision for income taxes	$ 30.4	$ 15.1