Business Segment Information - Reconciles of Segment Gross Profit to Income (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Reconciliation of segment gross profit to income from continuing operations before provision for income taxes
Segment gross profit	$ 275.9	$ 269.2	$ 329.8
Provision for doubtful accounts	(8.5)	(5.4)	(15.8)
Selling, general and administrative	(182.4)	(220.6)	(215.4)
Earnings (Loss) from joint ventures	0.2	(1.9)	(0.3)
Loss on sale of business	(20.2)
Other income (expenses), net	4.3	(2.1)	(0.8)
Interest expense	(5.0)	(9.3)	(9.5)
Interest income	0.2	0.5	1.0
Income from continuing operations before provision for income taxes	$ 64.5	$ 30.4	$ 89.0