Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Earnings per Share
Effect to the participating securities as result of net loss			$ 0.0
Basic and Diluted EPS:
Income from continuing operations	$ 31.3	$ 14.4	55.6	$ 35.7
Less income attributable to participating shares	(0.2)	(0.1)	(0.5)	(0.3)
Income from continuing operations attributable to common shareholders	31.1	14.3	55.1	35.4
Loss from discontinued operations attributable to common shareholders	(15.8)	(0.7)	(52.0)	(0.4)
Net income (loss) attributable to common shareholders for earnings per share	$ 15.3	$ 13.6	$ 3.1	$ 35.0
Weighted Average Shares:
Weighted average common shares outstanding - basic	34.0	33.7	34.1	33.9
Additional shares from the assumed exercise of stock options	0.5	0.5	0.4	0.4
Weighted average common shares outstanding - diluted	34.5	34.2	34.5	34.3
Earnings (Loss) per share - basic:
Earnings from continuing operations	$ 0.91	$ 0.43	$ 1.62	$ 1.05
Loss from discontinued operations	(0.46)	(0.02)	(1.52)	(0.01)
Earnings per share - basic	0.45	0.41	0.10	1.04
Earnings (Loss) per share - diluted:
Earnings from continuing operations	0.90	0.42	1.60	1.04
Loss from discontinued operations	(0.46)	(0.02)	(1.52)	(0.01)
Earnings per share - diluted	$ 0.44	$ 0.40	$ 0.08	$ 1.03