Note 5 - Amounts Receivable
 6 Months Ended
Jun. 30, 2019
Notes to Financial Statements  
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]
5.
Amounts Receivable
 
Amounts receivable consisted of the following (in thousands):
 
   
June 30
, 2019
    
December 31, 2018
  
Research and development incentives
   $
1,022
     $
622
  
Sales-based taxes receivable
    
59
      
134
  
Other
    
31
      
24
  
Total amounts receivable
   $
1,112
     $
780