Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Earnings per Share
Effect, participating securities			$ 0.0
Basic and Diluted EPS:
Income from continuing operations	$ 22.6	$ 31.1	54.6	$ 31.6
Less income attributable to participating shares	(0.2)	(0.2)	(0.4)	(0.2)
Income from continuing operations attributable to common shareholders	22.4	30.9	54.2	31.4
Income (Loss) from discontinued operations attributable to common shareholders	(0.1)	(3.0)	0.2	(9.8)
Net income (loss) attributable to common stockholders for earnings per share	$ 22.3	$ 27.9	$ 54.4	$ 21.6
Weighted Average Shares:
Weighted average common shares outstanding - basic	35,100,000	35,000,000.0	35,300,000	35,000,000.0
Additional shares from assumed exercise of stock options	600,000	500,000	500,000	200,000
Weighted average common shares outstanding - diluted	35,700,000	35,500,000	35,800,000	35,200,000
Earnings per share - basic:
Earnings from continuing operations	$ 0.64	$ 0.88	$ 1.54	$ 0.90
Income (Loss) from discontinued operations	0	(0.09)	0.01	(0.28)
Earnings per share - basic	0.64	0.79	1.55	0.62
Earnings per share - diluted:
Earnings from continuing operations	0.63	0.87	1.52	0.89
Income (Loss) from discontinued operations	0	(0.08)	0.01	(0.28)
Earnings per share - diluted	$ 0.63	$ 0.79	$ 1.53	$ 0.61
Antidilutive shares excluded from the computation of diluted earnings per share (in shares)	247,000	653,000	771,000	1,187,000