RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value of Derivatives (Details) - CAD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Fair Value of Derivatives
Total net financial assets/(liabilities)	$ (934)	$ (359)
Fair Value
Fair Value of Derivatives
Current derivative assets	613	529
Long-term derivative assets	1,217	360
Current derivative liabilities	(1,159)	(717)
Long-term derivative liabilities	(1,605)	(531)
Total net financial assets/(liabilities)	(934)	(359)
Foreign exchange contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	(1,774)	(227)
Foreign exchange contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	65	259
Long-term derivative assets	320	240
Current derivative liabilities	(730)	(303)
Long-term derivative liabilities	(1,429)	(423)
Total net financial assets/(liabilities)	(1,774)	(227)
Interest rate contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	938	(22)
Interest rate contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	128	64
Long-term derivative assets	830	88
Current derivative liabilities	(17)	(150)
Long-term derivative liabilities	(3)	(24)
Total net financial assets/(liabilities)	938	(22)
Commodity contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	(104)	(115)
Commodity contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	414	204
Long-term derivative assets	66	29
Current derivative liabilities	(412)	(264)
Long-term derivative liabilities	(172)	(84)
Total net financial assets/(liabilities)	(104)	(115)
Other contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	6	5
Other contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	6	2
Long-term derivative assets	1	3
Current derivative liabilities	0
Long-term derivative liabilities	(1)
Total net financial assets/(liabilities)	6	5
Level 1 | Fair Value
Fair Value of Derivatives
Current derivative assets	120	38
Long-term derivative assets	0	0
Current derivative liabilities	(56)	(52)
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	64	(14)
Level 1 | Foreign exchange contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0	0
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	0	0
Level 1 | Interest rate contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0	0
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	0	0
Level 1 | Commodity contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	120	38
Long-term derivative assets	0	0
Current derivative liabilities	(56)	(52)
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	64	(14)
Level 1 | Other contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0
Long-term derivative liabilities	0
Total net financial assets/(liabilities)	0	0
Level 2 | Fair Value
Fair Value of Derivatives
Current derivative assets	341	396
Long-term derivative assets	1,175	352
Current derivative liabilities	(935)	(519)
Long-term derivative liabilities	(1,482)	(466)
Total net financial assets/(liabilities)	(901)	(237)
Level 2 | Foreign exchange contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	65	259
Long-term derivative assets	320	240
Current derivative liabilities	(730)	(303)
Long-term derivative liabilities	(1,429)	(423)
Total net financial assets/(liabilities)	(1,774)	(227)
Level 2 | Interest rate contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	128	64
Long-term derivative assets	830	88
Current derivative liabilities	(17)	(150)
Long-term derivative liabilities	(3)	(24)
Total net financial assets/(liabilities)	938	(22)
Level 2 | Commodity contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	142	71
Long-term derivative assets	24	21
Current derivative liabilities	(188)	(66)
Long-term derivative liabilities	(49)	(19)
Total net financial assets/(liabilities)	(71)	7
Level 2 | Other contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	6	2
Long-term derivative assets	1	3
Current derivative liabilities	0
Long-term derivative liabilities	(1)
Total net financial assets/(liabilities)	6	5
Level 3
Fair Value of Derivatives
Total net financial assets/(liabilities)	(97)
Level 3 | Fair Value
Fair Value of Derivatives
Current derivative assets	152	95
Long-term derivative assets	42	8
Current derivative liabilities	(168)	(146)
Long-term derivative liabilities	(123)	(65)
Total net financial assets/(liabilities)	(97)	(108)
Level 3 | Foreign exchange contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0	0
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	0	0
Level 3 | Interest rate contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0	0
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	0	0
Level 3 | Commodity contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	152	95
Long-term derivative assets	42	8
Current derivative liabilities	(168)	(146)
Long-term derivative liabilities	(123)	(65)
Total net financial assets/(liabilities)	(97)	(108)
Level 3 | Other contracts | Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Current derivative liabilities	0
Long-term derivative liabilities	0
Total net financial assets/(liabilities)	$ 0	$ 0