Note 5 - Amounts Receivable (Tables)
 6 Months Ended
Jun. 30, 2019
Notes Tables  
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]
   
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