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Stockholders' Equity - Additional Information (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Mar. 31, 2020
Nov. 30, 2014
Class of Stock [Line Items]            
Common stock, shares authorized   90,000,000.0        
Common stock, par value (usd per share)   $ 1        
Common stock, shares issued   67,800,000 66,900,000      
Common stock, shares outstanding   60,500,000 60,500,000      
Preference stock, shares authorized   800,000        
Preference stock, par value (usd per share)   $ 1        
Cash dividends declared per common share (usd per share)   $ 0.32 $ 0.32 $ 0.31    
Shares acquired   498,217 48,409 62,500    
Purchases of treasury stock   $ 13,700,000 $ 1,000,000.0 $ 1,200,000    
Cash dividends paid to stockholders   $ 19,400,000 $ 19,300,000 $ 18,700,000    
Subsequent Event            
Class of Stock [Line Items]            
Cash dividends declared per common share (usd per share) $ 0.09          
November 2014 Repurchase Program            
Class of Stock [Line Items]            
Share repurchase program, authorized amount           $ 75,000,000.0
March 2020 Repurchase Program            
Class of Stock [Line Items]            
Share repurchase program, authorized amount         $ 75,000,000.0