XML 51 R41.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stock Option Plans - Summary of Option Activity (Details)
 6 Months Ended
Jun. 30, 2018
USD ($)
$ / shares
shares
Number of Shares  
Outstanding at beginning of period (in shares) | shares 913,320
Granted (in shares) | shares 245,000
Exercised (in shares) | shares (7,650)
Expired/Forfeited (in shares) | shares (2,500)
Outstanding at end of period (in shares) | shares 1,148,170
Exercisable at end of period (in shares) | shares 634,920
Weighted Average Exercise Price per share  
Outstanding at beginning of period (in usd per share) | $ / shares $ 52.80
Granted (in usd per share) | $ / shares 49.46
Exercised (in usd per share) | $ / shares 41.82
Expired/Forfeited (in usd per share) | $ / shares 50.15
Outstanding at end of period (in usd per share) | $ / shares 52.17
Exercisable at end of period (in usd per share) | $ / shares $ 50.58
Aggregate Intrinsic Value  
Outstanding at beginning of period | $ $ 8,172,970
Granted | $ 1,009,400
Exercised | $ 153,306
Expired/Forfeited | $
Outstanding at end of period | $ 3,865,121
Exercisable at end of period | $ $ 2,852,934