RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Schedule of Foreign Exchange Derivative Instruments that are Designated and Qualify as Fair Value Hedges (Details) - CAD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
RISK MANAGEMENT AND FINANCIAL INSTRUMENTS
Realized gain/(loss) on derivative	$ 33	$ (17)	$ 132	$ (39)
Foreign exchange contracts | Fair value hedges
RISK MANAGEMENT AND FINANCIAL INSTRUMENTS
Unrealized loss on derivative	28	(29)	(14)	(92)
Unrealized gain on hedged item	(51)	26	(1)	100
Realized gain/(loss) on derivative	(36)	(12)	25	47
Realized loss on hedged item	$ 51	$ 0	$ (23)	$ (79)