Non-Operating Income (Expense) - Schedule of Non-Operating Income (Expense) (Detail) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Analysis of income and expense [abstract]
Foreign exchange losses	$ (2)	$ (4)
Gain on debt prepayment option (Note 30(b))	0	105
Loss on debt redemption or purchase (Note 19(b))	(11)	(224)
Other	56	26
Total non operating income (expense)	$ 43	$ (97)

The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2020-01-01
-Section A Statement of cash flows for an entity other than a financial institution
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&doctype=Illustrative%20Examples&dita_xref=IAS07_IE_A_TI
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2020-01-01
-Paragraph 52
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=21&code=ifrs-tx-2020-en-r&anchor=para_52_a&doctype=Standard
-URIDate 2020-01-01

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