Cash Flow Information (Details) - CAD CAD in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from (used in) operating activities [abstract]
Accounts receivable	CAD (228)	CAD (23)	CAD (77)
Prepaid expenses	(75)	5	(3)
Income taxes receivable	8	(4)	1
Inventory	(7)	11	(9)
Accounts payable, accrued liabilities, and provisions	186	81	(152)
Income taxes payable	2	3	(2)
Change in non-cash operating working capital	CAD (114)	CAD 73	CAD (242)

Adjustments for decrease (increase) in trade accounts receivable to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: Profit (loss)]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2017-01-01
-Paragraph 20
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_20_a&doctype=Standard
-URIDate 2017-03-09

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration