Annual reports filed by certain Canadian issuers pursuant to Section 15(d) and Rule 15d-4

Note 10 - Stock-based Compensation - Stock Option Fair Value Assumptions (Details)

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Note 10 - Stock-based Compensation - Stock Option Fair Value Assumptions (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Statement Line Items [Line Items]      
Risk-free interest rate 1.32% 0.68% 1.17%
Expected dividend yield  
Expected volatility 98.00% 110.00% 106.00%
Expected life of options (years) 5 5 5
Grant date fair value (2016 and 2015 values have been recast to US dollars -note 3(b)) $ 0.87 $ 2.30 $ 4.36