RELATED PARTIES - Post-employment Benefit Plans (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Related Party [Abstract]
Defined benefit plan	$ 20	$ 19

The amount of participation by the entity in a defined benefit plan that shares risks between group entities. [Refer: Defined benefit plans [member]; Related parties [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 24
-IssueDate 2019-01-01
-Paragraph 22
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2019-en-r&anchor=para_22&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_ParticipationInDefinedBenefitPlanThatSharesRisksBetweenGroupEntitiesRelatedPartyTransactions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration