Business Segment Information - Reconciliation of Gross Profit to Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2022	Nov. 30, 2021	Nov. 30, 2022	Nov. 30, 2021
Reconciliation of segment gross profit to income from continuing operations before provision for income taxes
Segment gross profit	$ 85.8	$ 78.4	$ 167.7	$ 143.0
Selling, general, and administrative	(52.8)	(47.1)	(102.9)	(96.4)
Loss from joint ventures	(0.7)	(0.4)	(1.3)	(0.6)
Provision for (Recovery of) credit losses	0.1	(0.8)	0.1	(0.8)
Losses related to sale and exit of business	(0.1)	(1.3)	(0.1)	(1.3)
Other income, net	0.5	0.3	0.7	1.0
Interest expense	(2.1)	(0.5)	(3.2)	(1.2)
Interest income	0.1	0.1	0.2	0.1
Income from continuing operations before provision for income taxes	$ 30.8	$ 28.7	$ 61.2	$ 43.8