Per Share Amounts - Additional Information (Detail) - CAD ($) $ / shares in Units, $ in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Dividends paid on common shares	$ 122	$ 102
Dividend paid per share	$ 0.10	$ 0.10

The amount of dividends paid per ordinary share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 34
-IssueDate 2017-01-01
-Paragraph 16A
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=34&date=2017-03-01&anchor=para_16A_f&doctype=Standard
-URIDate 2017-03-09

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