RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Fair Value of Derivatives (Details) - CAD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	$ 1,015	$ 529
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Deferred amounts and other assets	Deferred amounts and other assets
Current derivative liabilities	$ (898)	$ (717)
Derivative Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other long-term liabilities	Other long-term liabilities
Total net financial asset/(liability)	$ (546)	$ (359)
Foreign exchange contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(1,327)	(227)
Interest rate contracts
Fair Value of Derivatives
Total net financial asset/(liability)	910	(22)
Commodity contracts
Fair Value of Derivatives
Total net financial asset/(liability)	(139)	(115)
Other contracts
Fair Value of Derivatives
Total net financial asset/(liability)	10	5
Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	1,015	529
Long-term derivative assets	627	360
Current derivative liabilities	(898)	(717)
Long-term derivative liabilities	(1,290)	(531)
Total net financial asset/(liability)	(546)	(359)
Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	46	259
Long-term derivative assets	309	240
Current derivative liabilities	(566)	(303)
Long-term derivative liabilities	(1,116)	(423)
Total net financial asset/(liability)	(1,327)	(227)
Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	660	64
Long-term derivative assets	254	88
Current derivative liabilities		(150)
Long-term derivative liabilities	(4)	(24)
Total net financial asset/(liability)	910	(22)
Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	302	204
Long-term derivative assets	61	29
Current derivative liabilities	(332)	(264)
Long-term derivative liabilities	(170)	(84)
Total net financial asset/(liability)	(139)	(115)
Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	7	2
Long-term derivative assets	3	3
Total net financial asset/(liability)	10	5
Level 1 \| Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	65	38
Long-term derivative assets	0	0
Current derivative liabilities	(60)	(52)
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	5	(14)
Level 1 \| Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	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 \| Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	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 \| Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	65	38
Long-term derivative assets	0	0
Current derivative liabilities	(60)	(52)
Long-term derivative liabilities	0	0
Total net financial asset/(liability)	5	(14)
Level 1 \| Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	0	0
Long-term derivative assets	0	0
Total net financial asset/(liability)	0	0
Level 2 \| Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	803	396
Long-term derivative assets	583	352
Current derivative liabilities	(643)	(519)
Long-term derivative liabilities	(1,158)	(466)
Total net financial asset/(liability)	(415)	(237)
Level 2 \| Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	46	259
Long-term derivative assets	309	240
Current derivative liabilities	(566)	(303)
Long-term derivative liabilities	(1,116)	(423)
Total net financial asset/(liability)	(1,327)	(227)
Level 2 \| Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	660	64
Long-term derivative assets	254	88
Current derivative liabilities		(150)
Long-term derivative liabilities	(4)	(24)
Total net financial asset/(liability)	910	(22)
Level 2 \| Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	90	71
Long-term derivative assets	17	21
Current derivative liabilities	(77)	(66)
Long-term derivative liabilities	(38)	(19)
Total net financial asset/(liability)	(8)	7
Level 2 \| Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	7	2
Long-term derivative assets	3	3
Total net financial asset/(liability)	10	5
Level 3
Fair Value of Derivatives
Total net financial asset/(liability)	(136)
Level 3 \| Fair Value
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	147	95
Long-term derivative assets	44	8
Current derivative liabilities	(195)	(146)
Long-term derivative liabilities	(132)	(65)
Total net financial asset/(liability)	(136)	(108)
Level 3 \| Fair Value \| Foreign exchange contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	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 \| Fair Value \| Interest rate contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	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 \| Fair Value \| Commodity contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	147	95
Long-term derivative assets	44	8
Current derivative liabilities	(195)	(146)
Long-term derivative liabilities	(132)	(65)
Total net financial asset/(liability)	(136)	(108)
Level 3 \| Fair Value \| Other contracts
Fair Value of Derivatives
Short-term portion of derivative assets (Note 24)	0	0
Long-term derivative assets	0	0
Total net financial asset/(liability)	$ 0	$ 0

Indicates line item in statement of financial position that includes derivative asset classified as noncurrent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5618551-113959

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+ References

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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+ 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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