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Share-Based Compensation Plans - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares authorized under employee stock purchase plan (in shares) 3,250,000      
Shares available for grant or issuance under share-based compensation plans (in shares) 1,160,086      
Compensation expense to be recognized $ 8,700,000      
Maximum vesting period 3 years      
Tax benefit from exercise of stock options $ 2,600,000 $ 3,600,000 $ 3,900,000  
Excess tax benefit from share-based compensation 984,000 1,646,000 1,616,000  
Total intrinsic value of options exercised $ 1,200,000 $ 2,700,000 $ 2,300,000  
Options that were exercisable (in shares) 20,000 40,000 93,000  
Weighted average exercise price of exercisable options (in dollars per share) $ 24.48 $ 24.48 $ 24.48  
Total intrinsic value of options outstanding and exercisable $ 1,200,000 $ 1,400,000 $ 5,300,000  
Awards of Shares and Stock Units        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Compensation expense $ 11,400,000 $ 11,000,000.0 $ 9,900,000  
Stock Options        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares granted (in shares) 0 0 0  
Compensation expense $ 0 $ 0 $ 0  
Options outstanding 20,000 40,000 93,000 143,000
Restricted Stock Units (RSUs)        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares vested, but issuance deferred (in shares) 72,310      
Issuance deferral period 5 years      
Employee Stock Purchase Plan (in shares)        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares authorized under employee stock purchase plan (in shares) 3,000,000