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Consolidated Balance Sheets (Parenthetical) - CAD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Statement of Financial Position [Abstract] |  |
Property, plant and equipment, accumulated depreciation | $ 248,885 | $ 220,320
Common shares, authorized | unlimited | unlimited
Common shares, issued (in shares) | 27,088,816 | 28,070,150
Common shares, outstanding (in shares) | 27,088,816 | 28,070,150
Treasury shares (in shares) | 2,084,611 | 2,617,926

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