RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Total Derivative Instruments (Details) - CAD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	$ (2,250)	$ (404)
Total net derivative instruments	(2,250)	(404)
Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(2,251)	(278)
Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(4)	(122)
Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	5	(4)
Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(2,175)	(152)
Total net derivative instruments	(2,175)	(152)
Foreign exchange contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(2,180)	(148)
Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	0	$ 0
Derivative liability, statement of financial position [Extensible Enumeration]		Other long-term liabilities
Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	5	$ (4)
Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	53	(156)
Total net derivative instruments	53	$ (156)
Derivative liability, statement of financial position [Extensible Enumeration]		Other long-term liabilities
Interest rate contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	58	$ (52)
Derivative liability, statement of financial position [Extensible Enumeration]		Other long-term liabilities
Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(5)	$ (104)
Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	0	$ 0
Derivative liability, statement of financial position [Extensible Enumeration]		Other long-term liabilities
Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(131)	$ (96)
Total net derivative instruments	(131)	(96)
Commodity contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(132)	(78)
Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	1	(18)
Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	0	0
Other contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	3	1
Derivative liabilities, total gross derivative instruments as presented		(1)
Total net derivative asset/(liability)	3	0
Derivative assets, amounts available for offset	0	(1)
Derivative liabilities, amounts available for offset		1
Derivative assets, total net derivative instruments	3	0
Derivative liabilities, total net derivative instruments		0
Total net derivative instruments	3	0
Other contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	3	1
Derivative liabilities, total gross derivative instruments as presented		(1)
Total net derivative asset/(liability)	3	0
Other contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Derivative liabilities, total gross derivative instruments as presented		0
Total net derivative asset/(liability)	0	0
Other contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Derivative liabilities, total gross derivative instruments as presented		0
Total net derivative asset/(liability)	0	0
Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	557	623
Derivative assets, amounts available for offset	(259)	(335)
Derivative assets, total net derivative instruments	$ 298	$ 288
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets
Other current assets | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	$ 433	$ 551
Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	46	31
Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	78	41
Other current assets | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	125	139
Derivative assets, amounts available for offset	(29)	(32)
Derivative assets, total net derivative instruments	96	107
Other current assets | Foreign exchange contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	47	98
Other current assets | Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Other current assets | Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	78	41
Other current assets | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	67	65
Derivative assets, amounts available for offset	(39)	(32)
Derivative assets, total net derivative instruments	28	33
Other current assets | Interest rate contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	23	34
Other current assets | Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	44	31
Other current assets | Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Other current assets | Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	362	418
Derivative assets, amounts available for offset	(191)	(270)
Derivative assets, total net derivative instruments	171	148
Other current assets | Commodity contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	360	418
Other current assets | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	2	0
Other current assets | Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	426	463
Derivative assets, amounts available for offset	(137)	(184)
Derivative assets, total net derivative instruments	$ 289	$ 279
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Deferred amounts and other assets	Deferred amounts and other assets
Deferred amounts and other assets | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	$ 417	$ 396
Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	9	51
Deferred amounts and other assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	16
Deferred amounts and other assets | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	83	335
Derivative assets, amounts available for offset	(71)	(122)
Derivative assets, total net derivative instruments	12	213
Deferred amounts and other assets | Foreign exchange contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	83	319
Deferred amounts and other assets | Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Deferred amounts and other assets | Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	16
Deferred amounts and other assets | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	146	53
Derivative assets, amounts available for offset	(27)	(21)
Derivative assets, total net derivative instruments	119	32
Deferred amounts and other assets | Interest rate contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	137	2
Deferred amounts and other assets | Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	9	51
Deferred amounts and other assets | Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Deferred amounts and other assets | Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	197	75
Derivative assets, amounts available for offset	(39)	(41)
Derivative assets, total net derivative instruments	158	34
Deferred amounts and other assets | Commodity contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	197	75
Deferred amounts and other assets | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Deferred amounts and other assets | Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Other current liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(1,335)	(738)
Derivative liabilities, amounts available for offset	259	335
Derivative liabilities, total net derivative instruments	$ (1,076)	$ (403)
Derivative liability, statement of financial position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Other current liabilities | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	$ (1,204)	$ (500)
Other current liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(58)	(194)
Other current liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(73)	(44)
Other current liabilities | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(804)	(128)
Derivative liabilities, amounts available for offset	29	32
Derivative liabilities, total net derivative instruments	(775)	(96)
Other current liabilities | Foreign exchange contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(731)	(84)
Other current liabilities | Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Other current liabilities | Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(73)	(44)
Other current liabilities | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(80)	(186)
Derivative liabilities, amounts available for offset	39	32
Derivative liabilities, total net derivative instruments	(41)	(154)
Other current liabilities | Interest rate contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(22)	(3)
Other current liabilities | Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(58)	(183)
Other current liabilities | Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Other current liabilities | Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(451)	(423)
Derivative liabilities, amounts available for offset	191	270
Derivative liabilities, total net derivative instruments	(260)	(153)
Other current liabilities | Commodity contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(451)	(412)
Other current liabilities | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	(11)
Other current liabilities | Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(1,898)	(752)
Derivative liabilities, amounts available for offset	137	184
Derivative liabilities, total net derivative instruments	$ (1,761)	$ (568)
Derivative liability, statement of financial position [Extensible Enumeration]	Other long-term liabilities	Other long-term liabilities
Other long-term liabilities | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	$ (1,897)	$ (725)
Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(1)	(10)
Other long-term liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	(17)
Other long-term liabilities | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(1,579)	(498)
Derivative liabilities, amounts available for offset	71	122
Derivative liabilities, total net derivative instruments	(1,508)	(376)
Other long-term liabilities | Foreign exchange contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(1,579)	(481)
Other long-term liabilities | Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Other long-term liabilities | Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	(17)
Other long-term liabilities | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(80)	(88)
Derivative liabilities, amounts available for offset	27	21
Derivative liabilities, total net derivative instruments	(53)	(67)
Other long-term liabilities | Interest rate contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(80)	(85)
Other long-term liabilities | Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	(3)
Other long-term liabilities | Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Other long-term liabilities | Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(239)	(166)
Derivative liabilities, amounts available for offset	39	41
Derivative liabilities, total net derivative instruments	(200)	(125)
Other long-term liabilities | Commodity contracts | Non-Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(238)	(159)
Other long-term liabilities | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(1)	(7)
Other long-term liabilities | Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	$ 0	$ 0