Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details)

v3.20.4
Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock units outstanding, beginning, number of shares 405,104 424,001 449,475
Granted, number of shares 216,318 177,618 197,299
Vested, number of shares (160,229) (163,195) (155,847)
Forfeited, number of shares (35,918) (33,320) (66,926)
Restricted stock units outstanding, ending, number of shares 425,275 405,104 424,001
Restricted stock units outstanding, beginning, weighted average grate date fair value per share $ 76.45 $ 62.38 $ 52.07
Granted, weighted average grant date fair value per share 78.90 94.58 73.74
Vested, weighted average grant date fair value 68.72 60.45 50.97
Forfeited, weighted average grant date fair value 79.36 72.35 53.19
Restricted stock units outstanding, ending, weighted average grate date fair value per share $ 80.37 $ 76.45 $ 62.38