Quarterly report pursuant to Section 13 or 15(d)

Employee Stock Plans - Summary of Restricted Stock Awards and Units (Details)

v3.20.2
Employee Stock Plans - Summary of Restricted Stock Awards and Units (Details) - $ / shares
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2020
Sep. 30, 2020
Dec. 31, 2019
2010 Plan | Common Stock      
Stock-based compensation      
Maximum number of shares of common stock that may be issued 2,130,000 2,130,000  
Performance Share Unit Awards | 2010 Plan      
Weighted Average Grant Date Fair Value      
Cancelled and forfeited (in dollars per share)   $ 53.50  
Restricted stock units      
Shares      
Unvested at the beginning of the period (in shares)   35,676  
Granted (in shares)   48,433  
Vested (in shares)   (47,196)  
Cancelled and forfeited (in shares)   (891)  
Unvested at the end of the period (in shares) 36,022 36,022 35,676
Expected to vest in the future, at the end of the period (in shares) 36,022 36,022  
Weighted Average Grant Date Fair Value      
Unvested at the beginning of the period (in dollars per share)   $ 36.49  
Granted (in dollars per share)   50.20  
Vested (in dollars per share)   45.71  
Cancelled and forfeited (in dollars per share)   50.20  
Unvested at the end of the period (in dollars per share) $ 42.73 42.73 $ 36.49
Expected to vest in the future, at the end of the period (in dollars per share) $ 42.73 $ 42.73  
Weighted Average Remaining Contractual Term      
Unvested at the beginning of the period 1 year 7 months 24 days   1 year 4 months 24 days
Granted   11 months 1 day  
Unvested at the end of the period 1 year 7 months 24 days   1 year 4 months 24 days
Expected to vest in future, at the end of the period 1 year 7 months 24 days