Other (expense) income - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Analysis of income and expense [abstract]
Losses on disposals of property, plant and equipment	$ 45
Gain (loss) on investment, equity loss of share obligation	43	$ 53
Gain (losses) on disposals of investments	$ 3	$ 18

The losses on the disposal of property, plant and equipment. [Refer: Property, plant and equipment]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
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-Subparagraph c
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-URIDate 2020-01-01

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Balance Type:	debit
Period Type:	duration