Annual report pursuant to Section 13 and 15(d)

Note 16 - Subsequent Events (Details Textual)

v3.20.1
Note 16 - Subsequent Events (Details Textual) - $ / shares
12 Months Ended
Mar. 10, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross   2,160,000 2,320,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price   $ 2 $ 2.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period   312,000 114,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price   $ 2.32 $ 2.04
Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross   160,000 166,000
Employee Stock Option Vesting Schedule II [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross   335,000 850,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   100.00%  
Share-based Payment Arrangement, Tranche One [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   50.00%  
Share-based Payment Arrangement, Tranche One [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   50.00% 50.00%
Share-based Payment Arrangement, Tranche Two [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   16.67% 16.67%
Share-based Payment Arrangement, Tranche Two [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   25.00% 25.00%
Share-based Payment Arrangement, Tranche Three [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   16.67% 16.67%
Share-based Payment Arrangement, Tranche Three [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   25.00% 25.00%
Share-based Compensation Award, Tranche Four [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   16.67% 16.67%
Subsequent Event [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross 5,808,834    
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price $ 6.82    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period 161,775    
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price $ 2.68    
Subsequent Event [Member] | Employee Stock Option Vesting Schedule II [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross 861,834    
Subsequent Event [Member] | Share-based Payment Arrangement, Tranche One [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 50.00%    
Subsequent Event [Member] | Share-based Payment Arrangement, Tranche One [Member] | Employee Stock Option Vesting Schedule II [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 50.00%    
Subsequent Event [Member] | Share-based Payment Arrangement, Tranche Two [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 16.67%    
Subsequent Event [Member] | Share-based Payment Arrangement, Tranche Two [Member] | Employee Stock Option Vesting Schedule II [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 25.00%    
Subsequent Event [Member] | Share-based Payment Arrangement, Tranche Three [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 16.67%    
Subsequent Event [Member] | Share-based Payment Arrangement, Tranche Three [Member] | Employee Stock Option Vesting Schedule II [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 25.00%    
Subsequent Event [Member] | Share-based Compensation Award, Tranche Four [Member] | Employee Stock Option Vesting Schedule I [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage 16.67%