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Stock Repurchase Program (Details) - USD ($)
12 Months Ended
Sep. 17, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Aug. 02, 2016
Nov. 04, 2014
Equity, Class of Treasury Stock [Line Items]            
Aggregate purchase price for repurchased shares   $ 53,035,000 $ 0 $ 0    
2016 and 2014 Share Repurchase Programs            
Equity, Class of Treasury Stock [Line Items]            
Remaining value of shares authorized for repurchase under stock repurchase programs   $ 54,900,000        
Number of shares repurchased (in shares)   0 0 0    
2016 Repurchase Program            
Equity, Class of Treasury Stock [Line Items]            
Value of shares authorized for repurchase under stock repurchase programs         $ 50,000,000.0  
2014 Share Repurchase Program            
Equity, Class of Treasury Stock [Line Items]            
Value of shares authorized for repurchase under stock repurchase programs           $ 50,000,000.0
One-Time Stock Repurchase Transaction            
Equity, Class of Treasury Stock [Line Items]            
Value of shares authorized for repurchase under stock repurchase programs $ 75,000,000.0          
Number of shares repurchased (in shares) 749,300          
Average price of repurchased shares (in dollars per share) $ 70.78          
Aggregate purchase price for repurchased shares $ 53,000,000.0