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Consolidated Balance Sheets (Parenthetical) - CAD CAD in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Property, plant and equipment, accumulated depreciation	CAD 220,320	CAD 204,860
Common shares, authorized	unlimited	unlimited
Common shares, issued (in shares)	28,070,150	30,518,907
Common shares, outstanding (in shares)	28,070,150	30,518,907
Treasury shares (in shares)	2,617,926	2,213,247

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Common stock share authorized.

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Number of previously issued common shares repurchased by the issuing entity and held in treasury.

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