Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Restricted Stock Awards and Units (Details)

v3.20.4
Stock-Based Compensation - Summary of Restricted Stock Awards and Units (Details) - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
2010 Plan | Common Stock        
Stock-based compensation        
Maximum number of shares of common stock that may be issued 2,130,000      
Number of shares of common stock available for grant 825,238      
Performance Share Unit Awards | 2010 Plan        
Weighted Average Grant Date Fair Value        
Granted (in dollars per share) $ 53.50 $ 36.48 $ 37.40  
Restricted stock units        
Shares        
Unvested at the beginning of the period (in shares) 35,676 45,599 47,542  
Granted (in shares) 49,349 47,360 134,804  
Vested (in shares) (48,112) (56,863) (136,747)  
Cancelled and forfeited (in shares) (891) (420)    
Unvested at the end of the period (in shares) 36,022 35,676 45,599 47,542
Expected to vest in the future, at the end of the period (in shares) 35,662      
Weighted Average Grant Date Fair Value        
Unvested at the beginning of the period (in dollars per share) $ 36.49 $ 33.28 $ 23.95  
Granted (in dollars per share) 49.90 36.48 35.73  
Vested (in dollars per share) 45.49 22.05 32.45  
Cancelled and forfeited (in dollars per share) 49.90 36.48    
Unvested at the end of the period (in dollars per share) 42.73 $ 36.49 $ 33.28 $ 23.95
Expected to vest in the future, at the end of the period (in dollars per share) $ 42.73      
Weighted Average Remaining Contractual Term        
Unvested at the beginning of the period 1 year 4 months 24 days 1 year 4 months 24 days 1 year 3 months 25 days 10 months 2 days
Granted 9 months 18 days 9 months 3 days 5 months 4 days  
Unvested at the end of the period 1 year 4 months 24 days 1 year 4 months 24 days 1 year 3 months 25 days 10 months 2 days
Expected to vest in future, at the end of the period 1 year 4 months 24 days