RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Schedule of the Consolidated Statements of Financial Position Location and Carrying Value of Derivative Instruments (Details) - CAD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	$ (926)	$ (2,250)
Derivative asset liability, amounts available for offset	0
Total net derivative asset/(liability)	(926)	(2,250)
Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(939)	(2,251)
Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	13	(4)
Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	0	5
Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(947)	(2,175)
Derivative asset liability, amounts available for offset	0
Total net derivative asset/(liability)	(947)	(2,175)
Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(947)	(2,180)
Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	0	0
Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(0)	5
Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	32	53
Derivative asset liability, amounts available for offset	0
Total net derivative asset/(liability)	32	53
Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	18	58
Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	14	(5)
Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	0	0
Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(11)	(131)
Derivative asset liability, amounts available for offset	0
Total net derivative asset/(liability)	(11)	(131)
Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(10)	(132)
Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net derivative asset/(liability)	(1)	1
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
Total net derivative asset/(liability)		3
Derivative assets, amounts available for offset		0
Derivative assets, total net derivative instruments		3
Total net derivative asset/(liability)		3
Other contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		3
Total net derivative asset/(liability)		3
Other contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		0
Total net derivative asset/(liability)		0
Other contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		0
Total net derivative asset/(liability)		0
Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	308	557
Derivative assets, amounts available for offset	(104)	(259)
Derivative assets, total net derivative instruments	$ 204	$ 298
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets
Debt and Equity Securities, Fair Value by Fair Value Hierarchy Level [Extensible Enumeration]	Other Assets, Current
Other current assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	$ 282	$ 433
Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	26	46
Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	78
Other current assets | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	33	125
Derivative assets, amounts available for offset	(19)	(29)
Derivative assets, total net derivative instruments	14	96
Other current assets | Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	33	47
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	0	78
Other current assets | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	32	67
Derivative assets, amounts available for offset	(15)	(39)
Derivative assets, total net derivative instruments	17	28
Other current assets | Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	20	23
Other current assets | Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	12	44
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	391	362
Derivative assets, amounts available for offset	(230)	(191)
Derivative assets, total net derivative instruments	161	171
Other current assets | Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	391	360
Other current assets | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	2
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	456	426
Derivative assets, amounts available for offset	(264)	(137)
Derivative assets, total net derivative instruments	$ 192	$ 289
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Deferred Costs and Other Assets	Deferred Costs and Other Assets
Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	$ 444	$ 417
Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	12	9
Deferred amounts and other assets | 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 | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	75	83
Derivative assets, amounts available for offset	(33)	(71)
Derivative assets, total net derivative instruments	42	12
Deferred amounts and other assets | Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	75	83
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	0
Deferred amounts and other assets | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	117	146
Derivative assets, amounts available for offset	(28)	(27)
Derivative assets, total net derivative instruments	89	119
Deferred amounts and other assets | Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	91	137
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	26	9
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	116	197
Derivative assets, amounts available for offset	(43)	(39)
Derivative assets, total net derivative instruments	73	158
Deferred amounts and other assets | Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	116	197
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	(922)	(1,335)
Derivative liabilities, amounts available for offset	104	259
Derivative liabilities, total net derivative instruments	$ (818)	$ (1,076)
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	$ (910)	$ (1,204)
Other current liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(12)	(58)
Other current liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	(73)
Other current liabilities | Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(334)	(804)
Derivative liabilities, amounts available for offset	19	29
Derivative liabilities, total net derivative instruments	(315)	(775)
Other current liabilities | Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(334)	(731)
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	0	(73)
Other current liabilities | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(38)	(80)
Derivative liabilities, amounts available for offset	15	39
Derivative liabilities, total net derivative instruments	(23)	(41)
Other current liabilities | Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(26)	(22)
Other current liabilities | Interest rate contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(12)	(58)
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	(396)	(451)
Derivative liabilities, amounts available for offset	230	191
Derivative liabilities, total net derivative instruments	(166)	(260)
Other current liabilities | Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(395)	(451)
Other current liabilities | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	1	0
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	(768)	(1,898)
Derivative liabilities, amounts available for offset	264	137
Derivative liabilities, total net derivative instruments	$ (504)	$ (1,761)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	$ (755)	$ (1,897)
Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(13)	(1)
Other long-term liabilities | Fair value 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
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(721)	(1,579)
Derivative liabilities, amounts available for offset	33	71
Derivative liabilities, total net derivative instruments	(688)	(1,508)
Other long-term liabilities | Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(721)	(1,579)
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	0
Other long-term liabilities | Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(79)	(80)
Derivative liabilities, amounts available for offset	28	27
Derivative liabilities, total net derivative instruments	(51)	(53)
Other long-term liabilities | Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(67)	(80)
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	(12)	0
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	(122)	(239)
Derivative liabilities, amounts available for offset	43	39
Derivative liabilities, total net derivative instruments	(79)	(200)
Other long-term liabilities | Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(122)	(238)
Other long-term liabilities | Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	(1)
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
Long-term Investments
TOTAL DERIVATIVE INSTRUMENTS
Debt and Equity Securities, Fair Value by Fair Value Hierarchy Level [Extensible Enumeration]	Long-Term Investments