Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Restricted Stock Activity (Details)

v3.20.4
Stockholders' Equity - Restricted Stock Activity (Details) - Restricted Stock - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Shares [Rollforward]      
Outstanding at beginning of period (shares)     133,294
Granted (shares) 111,306 118,498 62,133
Vested (shares) (52,363) (102,846) (61,989)
Forfeited (shares) 0 (666) (1,165)
Weighted-Average Grant Date Fair Value [Roll Forward]      
Outstanding at beginning of period (USD per share) $ 125.11 $ 130.63 $ 91.60
Granted (USD per share) 89.73 115.90 169.92
Vested (USD per share) 121.69 121.55 86.19
Forfeited (USD per share) 0 134.36 125.16
Outstanding at end of period (USD per share) $ 106.88 $ 125.11 $ 130.63