Annual report pursuant to Section 13 and 15(d)

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

v3.20.4
Stock-Based Compensation (Restricted Stock Units and Restricted Stock Awards) (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Stock-based compensation expense   $ 4,286  
Fair value adjustment gain on settlement $ 2,524    
Restricted Stock Units | Tranche One      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting percent 33.333%    
Restricted Stock Units | Tranche Two      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting percent 33.333%    
Restricted Stock Units | Tranche Three      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting percent 33.333%    
Unvested restricted stock units and awards      
Number of Shares      
Balance at the beginning of the period (in shares) 1,318,870 1,461,468 1,629,971
Granted (in shares) 970,390 997,971 940,113
Vested (in shares) (804,982) (1,029,790) (1,005,347)
Forfeited (in shares) (138,931) (110,779) (103,269)
Balance at the end of the period (in shares) 1,345,347 1,318,870 1,461,468
Weighted-Average Grant Date Fair Value per Share      
Balance at the beginning of the period (in dollars per share) $ 58.88 $ 46.59 $ 32.60
Granted (in dollars per share) 74.61 61.91 55.24
Vested (in dollars per share) 57.77 45.11 32.73
Forfeited (in dollars per share) 62.14 53.16 40.37
Balance at the end of the period (in dollars per share) $ 70.56 $ 58.88 $ 46.59
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Unrecognized compensation expense related to shares $ 72,238    
Unrecognized compensation expense weighted-average recognition period 1 year 10 months 24 days    
Performance Shares (PSUs)      
Number of Shares      
Balance at the beginning of the period (in shares) 254,118 124,320 136,668
Granted (in shares) 81,689 202,168 55,986
Vested (in shares) 0 (68,334) (68,334)
Forfeited (in shares) (33,010) (4,036) 0
Balance at the end of the period (in shares) 302,797 254,118 124,320
Weighted-Average Grant Date Fair Value per Share      
Balance at the beginning of the period (in dollars per share) $ 67.96 $ 44.64 $ 31.03
Granted (in dollars per share) 83.47 69.68 61.25
Vested (in dollars per share) 0 31.03 31.03
Forfeited (in dollars per share) 64.70 61.27 0
Balance at the end of the period (in dollars per share) $ 72.50 $ 67.96 $ 44.64
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Vesting period 3 years    
Unrecognized compensation expense related to shares $ 8,201    
Unrecognized compensation expense weighted-average recognition period 1 year 9 months 18 days    
Minimum | Performance Shares (PSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Number of shares to be vest upon each evaluation date 50.00%    
Maximum | Performance Shares (PSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]      
Number of shares to be vest upon each evaluation date 150.00%