LEASES - Lease Commitments (Details) - CAD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating leases
2024	$ 130
2025	120
2026	106
2027	96
2028	75
Thereafter	459
Total undiscounted lease payments	986
Less imputed interest	(236)
Total	750	$ 764
Finance leases
2024	31
2025	25
2026	25
2027	18
2028	18
Thereafter	502
Total undiscounted lease payments	619
Less imputed interest	(336)
Total finance lease liabilities	$ 283	$ 56