v3.26.1
Shareholders' Equity - Schedule of Changes in Shareholders' Equity (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Increase (Decrease) in Stockholders' Equity            
Beginning balance $ 1,562.7 $ 1,543.9 $ 1,461.8 $ 1,428.6 $ 1,543.9 $ 1,428.6
Net income 27.1 27.4 26.4 24.5 54.5 50.9
Other comprehensive income (loss) (1.8) 2.3 10.4 13.5   23.9
Dividends (6.8) (6.8) (6.5) (6.6)    
Incentive plan activity 6.2 (4.1) 4.0 1.8    
Ending balance $ 1,587.4 $ 1,562.7 $ 1,496.1 $ 1,461.8 $ 1,587.4 $ 1,496.1
Cash dividends per share, declared (in dollars per share) $ 0.32 $ 0.32 $ 0.31 $ 0.31    
Common Stock            
Increase (Decrease) in Stockholders' Equity            
Beginning balance (in shares) 21.1 21.1 21.0 21.0 21.1 21.0
Beginning balance $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2
Ending balance (in shares) 21.1 21.1 21.0 21.0 21.1 21.0
Ending balance $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2 $ 0.2
Additional Paid-in Capital            
Increase (Decrease) in Stockholders' Equity            
Beginning balance 329.2 333.3 321.2 319.4 333.3 319.4
Incentive plan activity 6.2 (4.1) 4.0 1.8    
Ending balance 335.4 329.2 325.2 321.2 335.4 325.2
Retained Earnings            
Increase (Decrease) in Stockholders' Equity            
Beginning balance 1,210.3 1,189.7 1,193.5 1,175.6 1,189.7 1,175.6
Net income 27.1 27.4 26.4 24.5    
Dividends (6.8) (6.8) (6.5) (6.6)    
Ending balance 1,230.6 1,210.3 1,213.4 1,193.5 1,230.6 1,213.4
Accumulated Other Comprehensive Income (Loss)            
Increase (Decrease) in Stockholders' Equity            
Beginning balance 24.2 21.9 (51.9) (65.4) 21.9 (65.4)
Other comprehensive income (loss) (1.8) 2.3 10.4 13.5    
Ending balance 22.4 24.2 (41.5) (51.9) 22.4 (41.5)
Treasury Stock            
Increase (Decrease) in Stockholders' Equity            
Beginning balance (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)