RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value of Derivatives (Details) - CAD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Fair Value of Derivatives
Total net financial asset/(liability)	$ (561)	$ (546)
Fair Value
Fair Value of Derivatives
Current derivative assets	532	1,015
Long-term derivative assets	479	627
Current derivative liabilities	(399)	(898)
Long-term derivative liabilities	(1,173)	(1,290)
Total net financial asset/(liability)	(561)	(546)
Foreign exchange contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(775)	(1,327)
Foreign exchange contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	122	46
Long-term derivative assets	214	309
Current derivative liabilities	(131)	(566)
Long-term derivative liabilities	(980)	(1,116)
Total net financial asset/(liability)	(775)	(1,327)
Interest rate contracts
Fair Value of Derivatives
Total net financial asset/(liability)	344	910
Interest rate contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	215	660
Long-term derivative assets	198	254
Current derivative liabilities	(20)
Long-term derivative liabilities	(49)	(4)
Total net financial asset/(liability)	344	910
Commodity contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(132)	(139)
Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	193	302
Long-term derivative assets	67	61
Current derivative liabilities	(248)	(332)
Long-term derivative liabilities	(144)	(170)
Total net financial asset/(liability)	(132)	(139)
Other contracts
Fair Value of Derivatives
Total net financial asset/(liability)	2	10
Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	2	7
Long-term derivative assets		3
Total net financial asset/(liability)	2	10
Level 1 \| Fair Value
Fair Value of Derivatives
Current derivative assets	46	65
Long-term derivative assets	0	0
Current derivative liabilities	(36)	(60)
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	10	5
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 asset/(liability)	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
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	0	0
Level 1 \| Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	46	65
Long-term derivative assets	0	0
Current derivative liabilities	(36)	(60)
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	10	5
Level 1 \| Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets		0
Total net financial asset/(liability)	0	0
Level 2 \| Fair Value
Fair Value of Derivatives
Current derivative assets	402	803
Long-term derivative assets	429	583
Current derivative liabilities	(199)	(643)
Long-term derivative liabilities	(1,055)	(1,158)
Total net financial asset/(liability)	(423)	(415)
Level 2 \| Foreign exchange contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	122	46
Long-term derivative assets	214	309
Current derivative liabilities	(131)	(566)
Long-term derivative liabilities	(980)	(1,116)
Total net financial asset/(liability)	(775)	(1,327)
Level 2 \| Interest rate contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	215	660
Long-term derivative assets	198	254
Current derivative liabilities	(20)
Long-term derivative liabilities	(49)	(4)
Total net financial asset/(liability)	344	910
Level 2 \| Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	63	90
Long-term derivative assets	17	17
Current derivative liabilities	(48)	(77)
Long-term derivative liabilities	(26)	(38)
Total net financial asset/(liability)	6	(8)
Level 2 \| Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	2	7
Long-term derivative assets		3
Total net financial asset/(liability)	2	10
Level 3
Fair Value of Derivatives
Total net financial asset/(liability)	(148)
Level 3 \| Fair Value
Fair Value of Derivatives
Current derivative assets	84	147
Long-term derivative assets	50	44
Current derivative liabilities	(164)	(195)
Long-term derivative liabilities	(118)	(132)
Total net financial asset/(liability)	(148)	(136)
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 asset/(liability)	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
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	0	0
Level 3 \| Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	84	147
Long-term derivative assets	50	44
Current derivative liabilities	(164)	(195)
Long-term derivative liabilities	(118)	(132)
Total net financial asset/(liability)	(148)	(136)
Level 3 \| Other contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	0	0
Long-term derivative assets		0
Total net financial asset/(liability)	$ 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 https://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 https://asc.fasb.org/extlink&oid=126966630&loc=d3e41228-113958

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Fair value, after the effects of master netting arrangements, of a financial liability or 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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