RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value Derivatives (Details) - CAD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Foreign Currency Fair Value Hedge Derivative [Line Items]
Realized loss on derivative	$ (345)	$ (225)	$ (483)	$ 36
Fair value hedges \| Interest rate contracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Unrealized gain on derivative	122	50	221	15
Unrealized loss on hedged item	(122)	(50)	(211)	(22)
Realized loss on derivative	(5)	(1)	(101)	(40)
Realized gain on hedged item	$ 0	$ 0	$ 85	$ 45

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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