RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Schedule of Derivative Assets and Liabilities Measured at Fair Value (Details) - CAD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Fair Value of Derivatives
Total net derivative asset/(liability)	$ (1,828)	$ (823)
Fair Value
Fair Value of Derivatives
Current derivative assets	1,598	591
Long-term derivative assets	254	293
Current derivative liabilities	(2,361)	(712)
Long-term derivative liabilities	(1,319)	(995)
Total net derivative asset/(liability)	(1,828)	(823)
Level 1 \| Fair Value
Fair Value of Derivatives
Current derivative assets	884	70
Long-term derivative assets	4	0
Current derivative liabilities	(1,212)	(55)
Long-term derivative liabilities	(8)	0
Total net derivative asset/(liability)	(332)	15
Level 2 \| Fair Value
Fair Value of Derivatives
Current derivative assets	189	192
Long-term derivative assets	183	176
Current derivative liabilities	(638)	(480)
Long-term derivative liabilities	(1,243)	(914)
Total net derivative asset/(liability)	(1,509)	(1,026)
Level 3
Fair Value of Derivatives
Total net derivative asset/(liability)	13
Level 3 \| Fair Value
Fair Value of Derivatives
Current derivative assets	525	329
Long-term derivative assets	67	117
Current derivative liabilities	(511)	(177)
Long-term derivative liabilities	(68)	(81)
Total net derivative asset/(liability)	13	188
Foreign exchange contracts
Fair Value of Derivatives
Total net derivative asset/(liability)	(1,532)	(1,104)
Foreign exchange contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	30	27
Long-term derivative assets	33	52
Current derivative liabilities	(508)	(364)
Long-term derivative liabilities	(1,087)	(819)
Total net derivative asset/(liability)	(1,532)	(1,104)
Foreign exchange contracts \| Level 1 \| 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 derivative asset/(liability)	0	0
Foreign exchange contracts \| Level 2 \| Fair Value
Fair Value of Derivatives
Current derivative assets	30	27
Long-term derivative assets	33	52
Current derivative liabilities	(508)	(364)
Long-term derivative liabilities	(1,087)	(819)
Total net derivative asset/(liability)	(1,532)	(1,104)
Foreign exchange contracts \| Level 3 \| 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 derivative asset/(liability)	(0)	0
Interest rate contracts
Fair Value of Derivatives
Total net derivative asset/(liability)	69	91
Interest rate contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	71	106
Long-term derivative assets	145	117
Current derivative liabilities	(28)	(48)
Long-term derivative liabilities	(119)	(84)
Total net derivative asset/(liability)	69	91
Interest rate contracts \| Level 1 \| 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 derivative asset/(liability)	0	0
Interest rate contracts \| Level 2 \| Fair Value
Fair Value of Derivatives
Current derivative assets	71	106
Long-term derivative assets	145	117
Current derivative liabilities	(28)	(48)
Long-term derivative liabilities	(119)	(84)
Total net derivative asset/(liability)	69	91
Interest rate contracts \| Level 3 \| 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 derivative asset/(liability)	0	0
Commodity contracts
Fair Value of Derivatives
Total net derivative asset/(liability)	(365)	190
Commodity contracts \| Fair Value
Fair Value of Derivatives
Current derivative assets	1,497	458
Long-term derivative assets	76	124
Current derivative liabilities	(1,825)	(300)
Long-term derivative liabilities	(113)	(92)
Total net derivative asset/(liability)	(365)	190
Commodity contracts \| Level 1 \| Fair Value
Fair Value of Derivatives
Current derivative assets	884	70
Long-term derivative assets	4	0
Current derivative liabilities	(1,212)	(55)
Long-term derivative liabilities	(8)	0
Total net derivative asset/(liability)	(332)	15
Commodity contracts \| Level 2 \| Fair Value
Fair Value of Derivatives
Current derivative assets	88	59
Long-term derivative assets	5	7
Current derivative liabilities	(102)	(68)
Long-term derivative liabilities	(37)	(11)
Total net derivative asset/(liability)	(46)	(13)
Commodity contracts \| Level 3 \| Fair Value
Fair Value of Derivatives
Current derivative assets	525	329
Long-term derivative assets	67	117
Current derivative liabilities	(511)	(177)
Long-term derivative liabilities	(68)	(81)
Total net derivative asset/(liability)	$ 13	$ 188

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