v3.26.1
Earnings per Common Share - Summary of Calculations of Basic and Diluted Loss from Continuing Operations per Common Share (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 12 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Dec. 31, 2025
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Sep. 30, 2024
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2024
Earnings Per Share [Abstract]                      
Net income $ 162.4 $ 139.6 $ 105.3 $ 122.5 $ 111.7 $ 95.4 $ 84.1 $ 84.8 $ 529.8 $ 376.0 $ 186.5
Dividends allocated to participating securities                 (0.2) (0.2) (0.3)
Earnings available for common stockholders used in calculation of basic earnings per common share                 $ 529.6 $ 375.8 $ 186.2
Weighted average number of common shares outstanding, basic (in shares) 49.9 50.0 50.1 50.1 50.1 50.2 50.2 50.1 50.0 50.2 49.7
Basic earnings per common share (in dollars per share) $ 3.25 $ 2.79 $ 2.10 $ 2.45 $ 2.23 $ 1.90 $ 1.68 $ 1.69 $ 10.59 $ 7.50 $ 3.75
Earnings available for common stockholders used in calculation of diluted earnings per common share                 $ 529.6 $ 375.8 $ 186.2
Effect of shares issuable under share-based compensation plans (in shares)                 0.4 0.5 0.6
Weighted average number of common shares outstanding, diluted (in shares) 50.2 50.3 50.3 50.4 50.6 50.7 50.7 50.7 50.4 50.7 50.3
Diluted earnings per common share (in dollars per share) $ 3.23 $ 2.77 $ 2.09 $ 2.43 $ 2.21 $ 1.88 $ 1.66 $ 1.67 $ 10.52 $ 7.42 $ 3.70