RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Total Derivative Instruments (Details) - CAD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	$ (404)	$ (546)
Total net derivative instruments	(404)	(546)
Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(278)	(1,476)
Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(122)	816
Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(4)	114
Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	623	1,015
Derivative assets, amounts available for offset	(335)	(223)
Derivative assets, total net derivative instruments	$ 288	$ 792
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	$ 551	$ 366
Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	31	649
Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	41	0
Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	463	627
Derivative assets, amounts available for offset	(184)	(163)
Derivative assets, total net derivative instruments	$ 279	$ 464
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	$ 396	$ 216
Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	51	255
Deferred amounts and other assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	16	156
Other current liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(738)	(898)
Derivative liabilities, amounts available for offset	335	223
Derivative liabilities, total net derivative instruments	$ (403)	$ (675)
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	$ (500)	$ (808)
Other current liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(194)	(48)
Other current liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(44)	(42)
Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(752)	(1,290)
Derivative liabilities, amounts available for offset	184	163
Derivative liabilities, total net derivative instruments	$ (568)	$ (1,127)
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	$ (725)	$ (1,250)
Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(10)	(40)
Other long-term liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(17)	0
Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(152)	(1,327)
Total net derivative instruments	(152)	(1,327)
Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(148)	(1,441)
Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial 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 financial asset/(liability)	$ (4)	114
Foreign exchange contracts | Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	139	46
Derivative assets, amounts available for offset	(32)	(41)
Derivative assets, total net derivative instruments	107	5
Foreign exchange contracts | Other current assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	98	46
Foreign exchange contracts | Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Foreign exchange contracts | Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	41	0
Foreign exchange contracts | Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	335	309
Derivative assets, amounts available for offset	(122)	(138)
Derivative assets, total net derivative instruments	213	171
Foreign exchange contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	319	153
Foreign exchange contracts | Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Foreign exchange contracts | Deferred amounts and other assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	16	156
Foreign exchange contracts | Other current liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(128)	(566)
Derivative liabilities, amounts available for offset	32	41
Derivative liabilities, total net derivative instruments	(96)	(525)
Foreign exchange contracts | Other current liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(84)	(524)
Foreign exchange contracts | Other current liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Foreign exchange contracts | Other current liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(44)	(42)
Foreign exchange contracts | Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(498)	(1,116)
Derivative liabilities, amounts available for offset	122	138
Derivative liabilities, total net derivative instruments	(376)	(978)
Foreign exchange contracts | Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(481)	(1,116)
Foreign exchange contracts | Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Foreign exchange contracts | Other long-term liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(17)	0
Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented		(4)
Total net financial asset/(liability)	(156)	910
Derivative liabilities, amounts available for offset		0
Derivative liabilities, total net derivative instruments		(4)
Total net derivative instruments	$ (156)	910
Derivative liability, statement of financial position [Extensible Enumeration]	Other long-term liabilities
Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented		(1)
Total net financial asset/(liability)	$ (52)	10
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
Derivative liabilities, total gross derivative instruments as presented		(3)
Total net financial asset/(liability)	$ (104)	900
Interest rate contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented		0
Total net financial asset/(liability)	$ 0	0
Derivative liability, statement of financial position [Extensible Enumeration]	Other long-term liabilities
Interest rate contracts | Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	$ 65	660
Derivative assets, amounts available for offset	(32)	0
Derivative assets, total net derivative instruments	33	660
Interest rate contracts | Other current assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	34	11
Interest rate contracts | Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	31	649
Interest rate contracts | Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Interest rate contracts | Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	53	254
Derivative assets, amounts available for offset	(21)	0
Derivative assets, total net derivative instruments	32	254
Interest rate contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	2	0
Interest rate contracts | Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	51	254
Interest rate contracts | 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
Interest rate contracts | Other current liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(186)
Derivative liabilities, amounts available for offset	32
Derivative liabilities, total net derivative instruments	(154)
Interest rate contracts | Other current liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(3)
Interest rate contracts | Other current liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(183)
Interest rate contracts | Other current liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0
Interest rate contracts | Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(88)
Derivative liabilities, amounts available for offset	21
Derivative liabilities, total net derivative instruments	(67)
Interest rate contracts | Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(85)
Interest rate contracts | Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(3)
Interest rate contracts | Other long-term liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0
Commodity contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(96)	(139)
Total net derivative instruments	(96)	(139)
Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(78)	(54)
Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(18)	(85)
Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	0	0
Commodity contracts | Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	418	302
Derivative assets, amounts available for offset	(270)	(182)
Derivative assets, total net derivative instruments	148	120
Commodity contracts | Other current assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	418	302
Commodity contracts | Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Commodity contracts | Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Commodity contracts | Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	75	61
Derivative assets, amounts available for offset	(41)	(25)
Derivative assets, total net derivative instruments	34	36
Commodity contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	75	61
Commodity contracts | Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0	0
Commodity contracts | 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
Commodity contracts | Other current liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(423)	(332)
Derivative liabilities, amounts available for offset	270	182
Derivative liabilities, total net derivative instruments	(153)	(150)
Commodity contracts | Other current liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(412)	(284)
Commodity contracts | Other current liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(11)	(48)
Commodity contracts | Other current liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	0	0
Commodity contracts | Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(166)	(170)
Derivative liabilities, amounts available for offset	41	25
Derivative liabilities, total net derivative instruments	(125)	(145)
Commodity contracts | Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(159)	(133)
Commodity contracts | Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, total gross derivative instruments as presented	(7)	(37)
Commodity contracts | 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 contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	1
Derivative liabilities, total gross derivative instruments as presented	(1)
Total net financial asset/(liability)	0	10
Derivative assets, amounts available for offset	(1)
Derivative liabilities, amounts available for offset	1
Derivative assets, total net derivative instruments	0
Derivative liabilities, total net derivative instruments	0
Total net derivative instruments	0	10
Other contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	1
Derivative liabilities, total gross derivative instruments as presented	(1)
Total net financial asset/(liability)	0	9
Other contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0
Derivative liabilities, total gross derivative instruments as presented	0
Total net financial asset/(liability)	0	1
Other contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented	0
Derivative liabilities, total gross derivative instruments as presented	0
Total net financial asset/(liability)	$ 0	0
Other contracts | Other current assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		7
Derivative assets, amounts available for offset		0
Derivative assets, total net derivative instruments		7
Other contracts | Other current assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		7
Other contracts | Other current assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		0
Other contracts | Other current assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		0
Other contracts | Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		3
Derivative assets, amounts available for offset		0
Derivative assets, total net derivative instruments		3
Other contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		2
Other contracts | Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		1
Other contracts | Deferred amounts and other assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, total gross derivative instruments as presented		$ 0