(Loss) Earnings per Common Share - Schedule of Calculations of Basic and Diluted Earnings from Continuing Operations per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net (loss) income	$ (229.6)	$ 1.5	$ 167.0
Dividends allocated to participating securities	(0.4)	(0.4)	(1.9)
(Loss) earnings available for common shareholders used in calculation of basic (loss) earnings per share	$ (230.0)	$ 1.1	$ 165.1
Weighted average number of common shares outstanding, basic (in shares)	48.3	48.1	47.7
Basic earnings per common share (in dollars per share)	$ (4.76)	$ 0.02	$ 3.46
(Loss) earnings available for common shareholders used in calculation of diluted (loss) earnings per share	$ (230.0)	$ 1.1	$ 165.1
Effect of shares issuable under share-based compensation plans (in shares)	0.0	0.1	0.4
Weighted average number of common shares outstanding, diluted (in shares)	48.3	48.2	48.1
Diluted earnings per common share (in dollars per share)	$ (4.76)	$ 0.02	$ 3.43