XML 61 R50.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stockholders' equity - Stock Option Activity (Details)
12 Months Ended
Dec. 31, 2018
$ / shares
shares
Number of options  
Beginning balance (in shares) | shares 227,203
Issued (in shares) | shares 113,561
Expired (in shares) | shares (800)
Ending balance (in shares) | shares 339,964
Exercisable (in shares) | shares 303,986
Weighted average exercise price  
Beginning balance (in dollars per share) | $ / shares $ 9.39
Issued (in dollars per share) | $ / shares 2.50
Expired (in dollars per share) | $ / shares 9.90
Ending balance (in dollars per share) | $ / shares 7.09
Exercisable (in dollars per share) | $ / shares $ 6.94