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

Contributed surplus (Schedule of Weighted Average Assumptions) (Details)

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Contributed surplus (Schedule of Weighted Average Assumptions) (Details) - Years
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [abstract]    
Risk-free interest rate 2.02% 2.70%
Expected volatility 77.00% 98.00%
Expected life (years) 4.2 4.4
Forfeiture rate 5.00% 4.00%