Significant accounting policies - Adoption of New or Amended Accounting Standards (Details) $ in Millions	Jan. 01, 2018 CAD ($)
IFRS 9
Disclosure of expected impact of initial application of new standards or interpretations [line items]
Increase in deficit	$ 4

The increase (decrease) in equity resulting from the appropriation of retained earnings. [Refer: Retained earnings]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_106_d&doctype=Standard
-URIDate 2018-03-16

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