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Income taxes - Narrative (Details) CAD in Thousands | 12 Months Ended
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Dec. 31, 2017 CAD provincial_jurisdiction | Dec. 31, 2016 CAD provincial_jurisdiction
Income Tax Disclosure [Abstract] |  |
Number of provincial jurisdictions | provincial_jurisdiction | 1 | 1
Deferred tax assets, non-capital operating loss carryforwards | CAD 17,584 |
Non-capital losses for income tax purposes | 65,126 |
Valuation allowance, amount | 1,035 | CAD 1,035
Operating loss carryforwards, not subject to expiration | CAD 7,664 |

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- Definition Operating Loss Carryforwards, Not Subject To Expiration + References No definition available. + Details
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are subject to expiration dates. + References No definition available. + Details
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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319 + Details
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