Financial Instruments - Reconciliation of Changes in the Fair Value of Available for Sale Financial Assets (Detail) - Level 3 of Fair Value Hierarchy [Member] $ in Millions	6 Months Ended
Jun. 30, 2019 CAD ($)
Disclosure Of Fair Value Measurement Of Assets [Line Items]
As at December 31, 2018	$ 38
Change in Fair Value	3
As at June 30, 2019	$ 41

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

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- Definition

The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_25&doctype=Standard
-URIDate 2018-03-16

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- Definition

The increase (decrease) in the fair value measurement of assets. [Refer: At fair value [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2018-01-01
-Paragraph 93
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2018-03-01&anchor=para_93_e&doctype=Standard
-URIDate 2018-03-16

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