Earnings 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, 2025	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income	$ 376.0	$ 186.5	$ 56.4
Dividends allocated to participating securities	(0.2)	(0.3)	(0.4)
Earnings available for common stockholders used in calculation of basic earnings per common share	$ 375.8	$ 186.2	$ 56.0
Weighted average number of common shares outstanding, basic (in shares)	50.2	49.7	48.8
Basic earnings (loss) per common share (in dollars per share)	$ 7.50	$ 3.75	$ 1.15
Earnings available for common stockholders used in calculation of diluted earnings per common share	$ 375.8	$ 186.2	$ 56.0
Effect of shares issuable under share-based compensation plans (in shares)	0.5	0.6	0.4
Weighted average number of common shares outstanding, diluted (in shares)	50.7	50.3	49.2
Diluted earnings (loss) per common share (in dollars per share)	$ 7.42	$ 3.70	$ 1.14