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Stockholders' Equity - Narrative Restricted Stock Awards and Stock Option Grants (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Class of Stock [Line Items]      
Weighted average exercise price (USD per share) $ 19.31 $ 19.27  
Deferred and Matching Restricted Stock Units      
Class of Stock [Line Items]      
Stock issued during period, MSPP (in shares) 0    
Restricted Stock      
Class of Stock [Line Items]      
Options vested in period, fair value $ 3.7 $ 3.3 $ 4.0
Grants in period, weighted average grant date fair value (USD per share) $ 17.43 $ 17.47 $ 15.49
Compensation not yet recognized,share-based awards other than options $ 6.3 $ 5.8  
Compensation cost not yet recognized, period for recognition 1 year 8 months 8 days 2 years 5 months 15 days  
Performance Restricted Stock Units      
Class of Stock [Line Items]      
Grants in period, weighted average grant date fair value (USD per share)   $ 17.34 $ 14.60
Compensation not yet recognized,share-based awards other than options $ 0.9 $ 0.9  
Compensation cost not yet recognized, period for recognition 1 year 8 months 26 days 1 year 10 months 13 days  
Total unrecognized compensation costs related to stock option awards (in years) $ 0.8 $ 0.8 $ 0.7
Employee Stock Option      
Class of Stock [Line Items]      
Compensation cost not yet recognized, period for recognition 1 year 8 months 8 days 2 years 3 months 25 days  
Weighted average exercise price (USD per share) $ 5.98 $ 6.30 $ 5.81
Total unrecognized compensation costs related to stock option awards $ 2.7 $ 3.4