Earnings (Loss) per Common Share - Schedule of Calculations of Basic and Diluted Loss from Continuing Operations per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net income (loss)	$ 56.4	$ (49.1)	$ (229.6)
Dividends allocated to participating securities	(0.4)	(0.1)	(0.4)
Earnings (loss) available for common shareholders used in calculation of basic earnings (loss) per share	$ 56.0	$ (49.2)	$ (230.0)
Weighted average number of common shares outstanding, basic (in shares)	48.8	48.5	48.3
Basic earnings (loss) per common share (in dollars per share)	$ 1.15	$ (1.01)	$ (4.76)
Earnings (loss) available for common shareholders used in calculation of diluted earnings (loss) per share	$ 56.0	$ (49.2)	$ (230.0)
Effect of shares issuable under share-based compensation plans (in shares)	0.4	0.0	0.0
Weighted average number of common shares outstanding, diluted (in shares)	49.2	48.5	48.3
Diluted earnings (loss) per common share (in dollars per share)	$ 1.14	$ (1.01)	$ (4.76)