v3.26.3
Shareholders' Equity - Schedule of Changes in Shareholders' Equity (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Jun. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2026
Sep. 30, 2025
Increase (Decrease) in Stockholders' Equity                
Beginning balance $ 1,587.4 $ 1,562.7 $ 1,543.9 $ 1,496.1 $ 1,461.8 $ 1,428.6 $ 1,543.9 $ 1,428.6
Net income 40.3 27.1 27.4 21.6 26.4 24.5 94.8 72.5
Other comprehensive income 3.0 (1.8) 2.3 4.7 10.4 13.5   28.6
Dividends (6.8) (6.8) (6.8) (6.6) (6.5) (6.6)    
Incentive plan activity 4.0 6.2 (4.1) 5.3 4.0 1.8    
Ending balance $ 1,627.9 $ 1,587.4 $ 1,562.7 $ 1,521.1 $ 1,496.1 $ 1,461.8 $ 1,627.9 $ 1,521.1
Cash dividends per share, declared (in dollars per share) $ 0.32 $ 0.32 $ 0.32 $ 0.31 $ 0.31 $ 0.31    
Common Stock                
Increase (Decrease) in Stockholders' Equity                
Beginning balance (in shares) 21.1 21.1 21.1 21.0 21.0 21.0 21.1 21.0
Beginning balance $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2
Ending balance (in shares) 21.1 21.1 21.1 21.0 21.0 21.0 21.1 21.0
Ending balance $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2
Additional Paid-in Capital                
Increase (Decrease) in Stockholders' Equity                
Beginning balance 335.4 329.2 333.3 325.2 321.2 319.4 333.3 319.4
Incentive plan activity 4.0 6.2 (4.1) 5.3 4.0 1.8    
Ending balance 339.4 335.4 329.2 330.5 325.2 321.2 339.4 330.5
Retained Earnings                
Increase (Decrease) in Stockholders' Equity                
Beginning balance 1,230.6 1,210.3 1,189.7 1,213.4 1,193.5 1,175.6 1,189.7 1,175.6
Net income 40.3 27.1 27.4 21.6 26.4 24.5    
Dividends (6.8) (6.8) (6.8) (6.6) (6.5) (6.6)    
Ending balance 1,264.1 1,230.6 1,210.3 1,228.4 1,213.4 1,193.5 1,264.1 1,228.4
Accumulated Other Comprehensive Income (Loss)                
Increase (Decrease) in Stockholders' Equity                
Beginning balance 22.4 24.2 21.9 (41.5) (51.9) (65.4) 21.9 (65.4)
Other comprehensive income 3.0 (1.8) 2.3 4.7 10.4 13.5    
Ending balance 25.4 22.4 24.2 (36.8) (41.5) (51.9) 25.4 (36.8)
Treasury Stock                
Increase (Decrease) in Stockholders' Equity                
Beginning balance (1.2) (1.2) (1.2) (1.2) (1.2) (1.2) (1.2) (1.2)
Ending balance $ (1.2) $ (1.2) $ (1.2) $ (1.2) $ (1.2) $ (1.2) $ (1.2) $ (1.2)