RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value of Derivatives (Details) - CAD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Fair Value of Derivatives
Total net financial assets/(liabilities)	$ 514	$ (359)
Fair Value
Fair Value of Derivatives
Current derivative assets	775	529
Long-term derivative assets	814	360
Current derivative liabilities	(633)	(717)
Long-term derivative liabilities	(442)	(531)
Total net financial assets/(liabilities)	514	(359)
Foreign exchange contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	296	(227)
Foreign exchange contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	342	259
Long-term derivative assets	470	240
Current derivative liabilities	(187)	(303)
Long-term derivative liabilities	(329)	(423)
Total net financial assets/(liabilities)	296	(227)
Interest rate contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	377	(22)
Interest rate contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	149	64
Long-term derivative assets	283	88
Current derivative liabilities	(51)	(150)
Long-term derivative liabilities	(4)	(24)
Total net financial assets/(liabilities)	377	(22)
Commodity contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	(174)	(115)
Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	274	204
Long-term derivative assets	56	29
Current derivative liabilities	(395)	(264)
Long-term derivative liabilities	(109)	(84)
Total net financial assets/(liabilities)	(174)	(115)
Other contracts
Fair Value of Derivatives
Total net financial assets/(liabilities)	15	5
Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	10	2
Long-term derivative assets	5	3
Total net financial assets/(liabilities)	15	5
Level 1 \| Fair Value
Fair Value of Derivatives
Current derivative assets	36	38
Long-term derivative assets	0	0
Current derivative liabilities	(27)	(52)
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	9	(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	36	38
Long-term derivative assets	0	0
Current derivative liabilities	(27)	(52)
Long-term derivative liabilities	0	0
Total net financial assets/(liabilities)	9	(14)
Level 1 \| Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Total net financial assets/(liabilities)	0	0
Level 2 \| Fair Value
Fair Value of Derivatives
Current derivative assets	673	396
Long-term derivative assets	782	352
Current derivative liabilities	(406)	(519)
Long-term derivative liabilities	(364)	(466)
Total net financial assets/(liabilities)	685	(237)
Level 2 \| Foreign exchange contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	342	259
Long-term derivative assets	470	240
Current derivative liabilities	(187)	(303)
Long-term derivative liabilities	(329)	(423)
Total net financial assets/(liabilities)	296	(227)
Level 2 \| Interest rate contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	149	64
Long-term derivative assets	283	88
Current derivative liabilities	(51)	(150)
Long-term derivative liabilities	(4)	(24)
Total net financial assets/(liabilities)	377	(22)
Level 2 \| Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	172	71
Long-term derivative assets	24	21
Current derivative liabilities	(168)	(66)
Long-term derivative liabilities	(31)	(19)
Total net financial assets/(liabilities)	(3)	7
Level 2 \| Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	10	2
Long-term derivative assets	5	3
Total net financial assets/(liabilities)	15	5
Level 3
Fair Value of Derivatives
Total net financial assets/(liabilities)	(180)
Level 3 \| Fair Value
Fair Value of Derivatives
Current derivative assets	66	95
Long-term derivative assets	32	8
Current derivative liabilities	(200)	(146)
Long-term derivative liabilities	(78)	(65)
Total net financial assets/(liabilities)	(180)	(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	66	95
Long-term derivative assets	32	8
Current derivative liabilities	(200)	(146)
Long-term derivative liabilities	(78)	(65)
Total net financial assets/(liabilities)	(180)	(108)
Level 3 \| Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets	0	0
Total net financial assets/(liabilities)	$ 0	$ 0

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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No definition available.

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