DEBT - Narrative (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Line of Credit Facility [Line Items]
Long-term debt and lease obligation	$ 97,159	$ 93,414
Increase (decrease) from cumulative fair value adjustments	(465)	(468)
Commercial Paper And Credit Facility Draws
Line of Credit Facility [Line Items]
Long-term debt and lease obligation	11,200	10,300
Fixed To Floating Subordinated Term Notes | Subordinated Term Notes
Line of Credit Facility [Line Items]
Subordinated debt	15,500	15,500
Uncommitted Demand Credit Facilities
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,500	1,400
Unutilized amount of facility	$ 882	$ 931
Commitment fee (as percent)	0.10%