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Income taxes - Narrative (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 CAD ($) provincial_jurisdiction | Dec. 31, 2017 CAD ($) provincial_jurisdiction
Income Tax Disclosure [Abstract] |  |
Number of provincial jurisdictions | provincial_jurisdiction | 1 | 1
Deferred tax assets, non-capital operating loss carryforwards | $ 23,443 |
Non-capital losses for income tax purposes | 86,826 |
Valuation allowance, amount | 1,035 | $ 1,035
Operating loss carryforwards, not subject to expiration | $ 7,664 |

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