Loss per Common Share - Schedule of calculations of basic and diluted earnings per common share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net loss	$ (14.8)	$ (47.1)
Dividends allocated to participating securities	0.0	0.0
Loss available for common stockholders used in calculation of basic loss per common share	$ (14.8)	$ (47.1)
Weighted average number of common shares outstanding, basic (in shares)	48.5	48.3
Basic loss per common share (in dollars per share)	$ (0.31)	$ (0.98)
Dividends allocated to participating securities	$ 0.0	$ 0.0
Loss available for common stockholders used in calculation of diluted loss per common share	$ (14.8)	$ (47.1)
Effect of shares issuable under share-based compensation plans (in shares)	0.0	0.0
Weighted average number of common shares outstanding, diluted (in shares)	48.5	48.3
Diluted loss per common share (in dollars per share)	$ (0.31)	$ (0.98)