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
9 Months Ended 12 Months Ended
Sep. 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 182 days 8 years 219 days
Options outstanding, Aggregate Intrinsic Value | $ $ 432,450 $ 249,154
Options granted, Shares (in shares) | shares 2,271,059  
Options granted, Weighted average exercise price (in dollars per share) | $ / shares $ 3.54  
Options exercised, Shares (in shares) | shares  
Options exercised, Weighted average exercise price (in dollars per share) | $ / shares  
Options canceled, Shares (in shares) | shares (666,718)  
Options canceled, Weighted average exercise price (in dollars per share) | $ / shares $ 5.55  
Options outstanding, Shares (in shares) | shares 4,298,565 2,694,224
Options outstanding, Weighted average exercise price (in dollars per share) | $ / shares $ 4.64 $ 5.80
Vested and exercisable and expected to vest, end of period, Number Of Shares (in shares) | shares 4,047,441  
Vested and exercisable and expected to vest, end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares $ 4.68  
Vested and exercisable and expected to vest, end of period, Weighted Average Remaining Contractual Term (Year) 8 years 146 days  
Vested and exercisable and expected to vest, end of period, Aggregate Intrinsic Value | $ $ 395,182  
Vested and exercisable, end of period, Number Of Shares (in shares) | shares 1,406,846  
Vested and exercisable, end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares $ 5.56  
Vested and exercisable, end of period, Weighted Average Remaining Contractual Term (Year) 7 years 36 days  
Vested and exercisable, end of period, Aggregate Intrinsic Value | $ $ 22,615