Assets Held for Sale and Discontinued Operations - Results of Discontinued Operations (Parenthetical) (Detail) - CAD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018
Disclosure Of Discontinued Operations [Abstract]
Net Deferred Tax Expense (Recovery)	$ (10)	$ 83

The tax expense relating to the gain (loss) on discontinuance when operations are discontinued. [Refer: Discontinued operations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 5
-IssueDate 2017-01-01
-Paragraph 33
-Subparagraph b
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=5&date=2017-03-01&anchor=para_33_b_iv&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2017-01-01
-Paragraph 81
-Subparagraph h
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_h_i&doctype=Standard
-URIDate 2017-03-09

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