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Financial instruments and risk management - Trade receivables (Details) (CAD) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012
Fair Value Disclosures [Abstract] |  |
Not past due | 59,337 | 81,752
Past due 1-30 days | 3,948 | 38,487
Past due 31-60 days | 1,538 | 14,142
More than 61 days | 3,541 | 17,480
Total | 68,364 | 151,861
Percentage of allowance for doubtful accounts that are more than 61 days past due | 100.00% |
Allowance for Doubtful Accounts Receivable [Roll Forward] |  |
Opening balance | 185 | 210
Payments received on provided balances | 0 | (1)
Current year allowance | 365 | 0
Write-offs | 0 | (24)
Ending balance | 0 | 185
Allowance for Doubtful Accounts Receivable, Discontinued Operations | (550) | 0

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- Definition Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3-4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Subparagraph a(1) -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 4 -Article 5 + Details
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