XML 51 R41.htm IDEA: XBRL DOCUMENT v3.8.0.1
Note 9 - Stock-based Compensation - Stock Option Activity (Details)
 3 Months Ended
Mar. 31, 2018
$ / shares
shares
Options outstanding (in shares) | shares 399,397
Options outstanding, weighted- average exercise price (in dollars per share) | $ / shares $ 51.14
Granted (in shares) | shares 22,450
Granted, weighted- average exercise price (in dollars per share) | $ / shares $ 105.75
Exercised (in shares) | shares (81,964)
Exercised, weighted- average exercise price (in dollars per share) | $ / shares $ 35.14
Forfeited (in shares) | shares (10,822)
Forfeited, weighted- average exercise price (in dollars per share) | $ / shares $ 61.94
Options outstanding (in shares) | shares 329,061
Options outstanding, weighted- average exercise price (in dollars per share) | $ / shares $ 58.50
Options exercisable (in shares) | shares 193,438
Options exercisable, weighted- average exercise price (in dollars per share) | $ / shares $ 48.70