RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value Derivatives (Details) - CAD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Foreign Currency Fair Value Hedge Derivative [Line Items]
Realized gain/(loss) on derivative	$ (22)	$ (55)
Fair value hedges \| Interest rate contracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Unrealized loss on derivative	(63)	(11)
Unrealized gain on hedged item	74	11
Realized gain/(loss) on derivative	59	(11)
Realized loss on hedged item	$ (79)	$ 0

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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-Topic 815
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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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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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Gain (loss) incurred in hedging activities.

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