Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - CAD / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Statement of changes in equity [abstract]
Dividends (in cad per share)	CAD 0.36	CAD 0.50

The amount, per share, of dividends recognised as distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 107
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_107&doctype=Standard
-URIDate 2017-03-09

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Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration