FOREIGN EXCHANGE - Detail of Gain (Loss) on Foreign Exchange (Details) - CAD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Effect Of Changes In Foreign Exchange Rates [Abstract]
Realized gain (loss) on foreign exchange	$ (797)	$ 277
Unrealized gain (loss) on foreign exchange	22,165	9,939
Unrealized gain (loss) on foreign exchange contracts	(3,867)	(2,021)
Gain (loss) on foreign exchange	$ 17,501	$ 8,195

The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2017-01-01
-Section A Statement of cash flows for an entity other than a financial institution
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=sect_AStatementofcashflowsforanentityotherthanafinancialinstitution&doctype=Illustrative%20Examples
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2017-01-01
-Paragraph 52
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=21&date=2017-03-01&anchor=para_52_a&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration