Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017
Effect to the participating securities as result of net loss			$ 0.0
Basic and Diluted EPS:
Income from continuing operations	$ 11.2	$ 13.2	30.1	$ 24.2
Less income attributable to participating shares	(0.1)	(0.1)	(0.1)	(0.1)
Income from continuing operations attributable to common shareholders	11.1	13.1	30.0	24.1
Loss from discontinued operations attributable to common shareholders	(4.2)	(35.8)	(8.0)	(36.2)
Net income (loss) attributable to common shareholders for earnings per share	$ 6.9	$ (22.7)	$ 22.0	$ (12.1)
Weighted Average Shares:
Weighted average common shares outstanding - basic	34,600,000	34,000,000	34,600,000	34,100,000
Additional shares from assumed exercise of stock options	400,000	500,000	500,000	400,000
Weighted average common shares outstanding - diluted	35,000,000	34,500,000	35,100,000	34,500,000
Earnings (Loss) per share - basic
Earnings from continuing operations	$ 0.32	$ 0.39	$ 0.87	$ 0.71
Loss from discontinued operations	(0.12)	(1.05)	(0.23)	(1.06)
Earnings (Loss) per share - basic	0.20	(0.66)	0.64	(0.35)
Earnings (Loss) per share - diluted
Earnings from continuing operations	0.32	0.38	0.85	0.70
Loss from discontinued operations	(0.12)	(1.04)	(0.23)	(1.05)
Earnings (Loss) per share - diluted	$ 0.20	$ (0.66)	$ 0.62	$ (0.35)
Stock options
Earnings (Loss) per share - diluted
Antidilutive shares excluded from the computation of diluted earnings per share (in shares)	290,000		290,000