v3.19.3
Note 10 - Stock Option Plans - Summary of Stock Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 6 Months Ended 12 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Note 9 - Stock Option Plans - Summary of Stock Option Activity (Details)        
Shares Available For Grant, Balance (in shares)   5,000 5,000 5,000
Number of Options, Alliqua options assumed in merger (in shares) 748,000 19,222 19,222 19,222
Weighted Average Exercise Price, Alliqua options assumed in merger (in dollars per share) $ 24.95 $ 0.10 $ 0.10 $ 0.10
Weighted Average Remaining Life in Years, outstanding (Year) 6 years 73 days 7 years 4 months 24 days 8 years 4 months 24 days 9 years 4 months 24 days
Intrinsic Value, outstanding $ 188 $ 6,956 [1] $ 6,639 [1]  
Options Outstanding, Vested and expected to vest (in shares)   19,222    
Weighted Average Exercise Price Per Share, Vested and expected to vest (in dollars per share)   $ 0.10    
Weighted-average Remaining Contractual Life, Vested and expected to vest (Year)   7 years 4 months 24 days    
Aggregate Intrinsic Value, Vested and expected to vest [1]   $ 6,956    
Number of Options, exercisable (in shares) 530,000 19,222,032    
Weighted Average Exercise Price, exercisable (in dollars per share) $ 33.93 $ 0.09    
Weighted Average Remaining Life in Years, exercisable (Year) 5 years 255 days 7 years 4 months 24 days    
Intrinsic Value, exercisable $ 188 $ 4,119 [1]    
[1] The aggregate intrinsic value is calculated as the difference between the stock option exercise price and the estimated fair value of the Company's common stock of $0.46 and $0.44 per share as of December 31, 2018 and 2017.