Quarterly report pursuant to Section 13 or 15(d)

Note 9 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details)

v3.10.0.1
Note 9 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details)
$ / shares in Units, $ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2018
USD ($)
$ / shares
shares
Dec. 31, 2017
USD ($)
$ / shares
shares
Options outstanding, Shares (in shares) | shares 2,694,224  
Options outstanding, Weighted average exercise price (in dollars per share) | $ / shares $ 5.80  
Options outstanding, Weighted Average Remaining Contractual Term (Year) 8 years 292 days 8 years 219 days
Options outstanding, Aggregate Intrinsic Value | $ $ 433,626 $ 249,154
Options granted, Shares (in shares) | shares 2,023,559  
Options granted, Weighted average exercise price (in dollars per share) | $ / shares $ 3.60  
Options exercised, Shares (in shares) | shares  
Options exercised, Weighted average exercise price (in dollars per share) | $ / shares  
Options canceled, Shares (in shares) | shares (508,428)  
Options canceled, Weighted average exercise price (in dollars per share) | $ / shares $ 5.66  
Options outstanding, Shares (in shares) | shares 4,209,355 2,694,224
Options outstanding, Weighted average exercise price (in dollars per share) | $ / shares $ 4.76 $ 5.80
Vested and exercisable and expected to vest, end of period, Number Of Shares (in shares) | shares 3,935,007  
Vested and exercisable and expected to vest, end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares $ 4.80  
Vested and exercisable and expected to vest, end of period, Weighted Average Remaining Contractual Term (Year) 8 years 255 days  
Vested and exercisable and expected to vest, end of period, Aggregate Intrinsic Value | $ $ 392,290  
Vested and exercisable, end of period, Number Of Shares (in shares) | shares 1,124,400  
Vested and exercisable, end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares $ 5.65  
Vested and exercisable, end of period, Weighted Average Remaining Contractual Term (Year) 7 years 182 days  
Vested and exercisable, end of period, Aggregate Intrinsic Value | $ $ 10,167