Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Restricted Stock (Details)

v3.19.3
Stock-Based Compensation - Restricted Stock (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Sep. 30, 2019
PSUs        
Stock-Based compensation        
Vesting period       3 years
Number of Shares        
Balance at the beginning of the period (in shares) 244,272 188,794 124,320 124,320
Granted (in shares) 3,495 123,812 68,510  
Vested (in shares) 0 (68,334) 0  
Forfeited (in shares) 0 0 (4,036)  
Balance at the end of the period (in shares) 247,767 244,272 188,794 247,767
Weighted-Average Grant Date Fair Value per Share        
Balance at the beginning of the period (in dollars per share) $ 67.78 $ 51.42 $ 44.64 $ 44.64
Granted (in dollars per share) 77.68 73.60 64.32  
Vested (in dollars per share) 0 31.03 0  
Forfeited (in dollars per share) 0 0 61.27  
Balance at the end of the period (in dollars per share) $ 67.98 $ 67.78 $ 51.42 $ 67.98
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]        
Unrecognized compensation expense related to shares $ 16,722     $ 16,722
Unrecognized compensation expense weighted-average recognition period       2 years 6 months
PSUs | Minimum        
Stock-Based compensation        
Number of shares to be vest upon each evaluation date, percentage 50.00%     50.00%
PSUs | Maximum        
Stock-Based compensation        
Number of shares to be vest upon each evaluation date, percentage 150.00%     150.00%
RSUs        
Number of Shares        
Balance at the beginning of the period (in shares) 1,745,165 1,833,263 1,461,468 1,461,468
Granted (in shares) 77,199 48,032 872,104  
Vested (in shares) (242,789) (114,056) (479,479)  
Forfeited (in shares) (39,734) (22,074) (20,830)  
Balance at the end of the period (in shares) 1,539,841 1,745,165 1,833,263 1,539,841
Weighted-Average Grant Date Fair Value per Share        
Balance at the beginning of the period (in dollars per share) $ 54.40 $ 53.67 $ 46.59 $ 46.59
Granted (in dollars per share) 71.49 68.50 60.94  
Vested (in dollars per share) 42.80 47.94 45.98  
Forfeited (in dollars per share) 54.61 56.55 48.31  
Balance at the end of the period (in dollars per share) $ 57.37 $ 54.40 $ 53.67 $ 57.37
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]        
Unrecognized compensation expense related to shares $ 74,375     $ 74,375
Unrecognized compensation expense weighted-average recognition period       2 years