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Financial instruments - Derivatives (Details) - CAD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Disclosure of detailed information about financial instruments [line items] |  |
Net | $ (57,506) | $ 17,390
Gain (loss) | (81,081) | 56,250
Current portion of other liabilities [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | (35,534) | (11,249)
Other liabilities [Member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | (25,853) | (12,165)
Current portion of long-term receivables, investments and other [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | 1,028 | 25,948
Long-term receivables, investments and other [Member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | 2,853 | 14,856
Foreign currency contracts [Member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | (52,665) | 34,360
Gain (loss) | (85,967) | 58,983
Interest rate swap contracts [member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | 857 | (150)
Gain (loss) | 2,032 | (4,014)
Uranium contracts [Member] |  |
Disclosure of detailed information about financial instruments [line items] |  |
Net | (5,698) | (16,820)
Gain (loss) | $ 2,854 | $ 1,281

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- Definition The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_85&doctype=Standard -URIDate 2018-03-16 + Details
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