Earnings Per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017
Earnings Per Share, Basic and Diluted [Abstract]
Net income (loss) attributable to Class A and Common Shares	$ 71.4	$ 57.0	$ 10.3	$ (6.6)
Weighted average Shares of Class A Stock and Common Stock outstanding for basic earnings (loss) per share	35.2	35.0	35.2	35.1
Dilutive effect of Class A Stock and Common Stock potentially issuable pursuant to stock-based compensation plans	0.7	0.6	0.6	0.0
Adjusted weighted average Shares of Class A Stock and Common Stock outstanding for diluted earnings (loss) per share	35.9	35.6	35.8	35.1
Earnings (loss) per share of Class A Stock and Common Stock:
Basic (in Dollars per share)	$ 2.03	$ 1.63	$ 0.29	$ (0.19)
Diluted (in Dollars per share)	$ 1.99	$ 1.60	$ 0.29	$ (0.19)