XML 36 R26.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stock-based Compensation - Stock Option (Details) - USD ($)
6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Additional disclosures    
Proceeds resulting from exercise of stock options $ 1,449,000  
Stock options    
Stock-based compensation expense    
Shares available for future issuance 1,239,595  
Shares    
Outstanding at the beginning of the period (in shares) 976,777  
Options granted (in shares) 218,900  
Options exercised (in shares) (58,170)  
Outstanding at the end of the period (in shares) 1,137,507  
Exercisable at the end of the period (in shares) 478,898  
Weighted average exercise price    
Outstanding at the beginning of the period (in dollars per share) $ 11.97  
Options granted (in dollars per share) 164.00  
Options exercised (in dollars per share) 24.90  
Outstanding at the end of the period (in dollars per share) 40.57  
Exercisable at the end of the period (in dollars per share) $ 11.19  
Additional disclosures    
Proceeds resulting from exercise of stock options $ 1,400,000 $ 0
Weighted-average grant date fair value of options (in dollars per share) $ 129.03 $ 12.68
Stock options | Maximum    
Stock-based compensation expense    
Expiration period 10 years