XML 58 R43.htm IDEA: XBRL DOCUMENT v3.20.1
Stockholders' equity - Additional Information (Details) - USD ($)
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average fair value of stock options granted (in dollars per share) $ 1.48    
Intrinsic value of options outstanding $ 0   $ 1,000
Intrinsic value of options exercisable 0   $ 0
Share-based compensation 205,353 $ 138,498  
Employee Stock Option      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation 121,000 $ 48,000  
Unearned share-based compensation expense $ 204,000    
Period of recognition 3 years