RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value Derivatives (Details) - CAD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Foreign Currency Fair Value Hedge Derivative [Line Items]
Realized loss on derivative	$ (55)	$ 94
Fair value hedges \| Interest rate contracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Unrealized gain/(loss) on derivative	(11)	76
Unrealized gain/(loss) on hedged item	11	(87)
Realized loss on derivative	(11)	(75)
Realized gain on hedged item	$ 0	$ 85

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Gain (loss) incurred in hedging activities.

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