LEASES - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease, expense	$ 131	$ 118	$ 95
Operating lease, payments	$ 129	$ 123	$ 118
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 month
Lessor, operating lease, remaining lease term	3 months
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	35 years
Lessor, operating lease, remaining lease term	28 years