XML 69 R57.htm IDEA: XBRL DOCUMENT v3.21.2
Stock award plan - Restricted Stock (Details) - Restricted stock
 6 Months Ended
Jun. 30, 2021
$ / shares
shares
Number of Shares  
Balance at the beginning of the period (in shares) | shares 982,058
Granted (in shares) | shares 951,558
Vested (in shares) | shares (319,127)
Forfeited (in shares) | shares (82,059)
Balance at the end of the period (in shares) | shares 1,532,430
Weighted Average Grant Date Fair Value  
Balance at the beginning of the period (in dollars per share) | $ / shares $ 41.78
Granted (in dollars per share) | $ / shares 64.21
Vested (in dollars per share) | $ / shares 35.21
Forfeited (in dollars per share) | $ / shares 57.75
Balance at the end of the period (in dollars per share) | $ / shares $ 56.23