RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value Derivatives (Details) - CAD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Foreign Currency Fair Value Hedge Derivative [Line Items]
Realized loss on derivative	$ (3)	$ 198	$ (52)	$ 104
Fair value hedges \| Interest rate contracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Unrealized gain/(loss) on derivative	(131)	23	(142)	99
Unrealized gain/(loss) on hedged item	130	(2)	141	(89)
Realized loss on derivative	(12)	(21)	(23)	(96)
Realized gain on hedged item	$ 0	$ 0	$ 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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-Topic 815
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-Name Accounting Standards Codification
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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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