RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Total Derivative Instruments (Details) - CAD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	$ (546)	$ (359)
Total Net Derivative Instruments	(546)	(359)
Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(1,476)	(202)
Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	816	(45)
Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	114	(112)
Accounts receivable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	1,015	529
Derivative assets, Amounts Available for Offset	(223)	(170)
Derivative assets, Total Net Derivative Instruments	$ 792	$ 359
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Accounts receivable and other (Note 9)	Accounts receivable and other (Note 9)
Accounts receivable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	$ 366	$ 465
Accounts receivable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	649	64
Accounts receivable and other | 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	627	360
Derivative assets, Amounts Available for Offset	(163)	(75)
Derivative assets, Total Net Derivative Instruments	$ 464	$ 285
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	$ 216	$ 272
Deferred amounts and other assets | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	255	88
Deferred amounts and other assets | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	156	0
Accounts payable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(898)	(717)
Derivative liabilities, Amounts Available for Offset	223	170
Derivative liabilities, Total Net Derivative Instruments	$ (675)	$ (547)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts payable and other (Note 17)	Accounts payable and other (Note 17)
Accounts payable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	$ (808)	$ (426)
Accounts payable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(48)	(179)
Accounts payable and other | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(42)	(112)
Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(1,290)	(531)
Derivative liabilities, Amounts Available for Offset	163	75
Derivative liabilities, Total Net Derivative Instruments	$ (1,127)	$ (456)
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	$ (1,250)	$ (513)
Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(40)	(18)
Other long-term liabilities | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	0	0
Foreign exchange contracts
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(1,327)	(227)
Total Net Derivative Instruments	(1,327)	(227)
Foreign exchange contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(1,441)	(100)
Foreign exchange contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	0	(15)
Foreign exchange contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	114	(112)
Foreign exchange contracts | Accounts receivable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	46	259
Derivative assets, Amounts Available for Offset	(41)	(41)
Derivative assets, Total Net Derivative Instruments	5	218
Foreign exchange contracts | Accounts receivable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	46	259
Foreign exchange contracts | Accounts receivable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	0	0
Foreign exchange contracts | Accounts receivable and other | Fair value 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
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	309	240
Derivative assets, Amounts Available for Offset	(138)	(61)
Derivative assets, Total Net Derivative Instruments	171	179
Foreign exchange contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	153	240
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	156	0
Foreign exchange contracts | Accounts payable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(566)	(303)
Derivative liabilities, Amounts Available for Offset	41	41
Derivative liabilities, Total Net Derivative Instruments	(525)	(262)
Foreign exchange contracts | Accounts payable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(524)	(176)
Foreign exchange contracts | Accounts payable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	0	(15)
Foreign exchange contracts | Accounts payable and other | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(42)	(112)
Foreign exchange contracts | Other long-term liabilities
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(1,116)	(423)
Derivative liabilities, Amounts Available for Offset	138	61
Derivative liabilities, Total Net Derivative Instruments	(978)	(362)
Foreign exchange contracts | Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(1,116)	(423)
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	0	0
Interest rate contracts
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(4)
Total net financial asset/(liability)	910	(22)
Derivative liabilities, Amounts Available for Offset	0
Total Net Derivative Instruments	910	(22)
Interest rate contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(1)
Total net financial asset/(liability)	10	(23)
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)	900	1
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
Interest rate contracts | Accounts receivable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	660	64
Derivative assets, Amounts Available for Offset	0	0
Derivative assets, Total Net Derivative Instruments	660	64
Interest rate contracts | Accounts receivable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	11	0
Interest rate contracts | Accounts receivable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	649	64
Interest rate contracts | Accounts receivable and other | 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	254	88
Derivative assets, Amounts Available for Offset	0	(1)
Derivative assets, Total Net Derivative Instruments	254	87
Interest rate contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	0	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	254	88
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 | Accounts payable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented		(150)
Derivative liabilities, Amounts Available for Offset		0
Derivative liabilities, Total Net Derivative Instruments		(150)
Interest rate contracts | Accounts payable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented		0
Interest rate contracts | Accounts payable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented		(150)
Interest rate contracts | Accounts payable and other | 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		(24)
Derivative liabilities, Amounts Available for Offset		1
Derivative liabilities, Total Net Derivative Instruments	(4)	(23)
Interest rate contracts | Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented		(23)
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		(1)
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)	(139)	(115)
Total Net Derivative Instruments	(139)	(115)
Commodity contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(54)	(84)
Commodity contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	(85)	(31)
Commodity contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	0	0
Commodity contracts | Accounts receivable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	302	204
Derivative assets, Amounts Available for Offset	(182)	(129)
Derivative assets, Total Net Derivative Instruments	120	75
Commodity contracts | Accounts receivable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	302	204
Commodity contracts | Accounts receivable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	0	0
Commodity contracts | Accounts receivable and other | 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	61	29
Derivative assets, Amounts Available for Offset	(25)	(13)
Derivative assets, Total Net Derivative Instruments	36	16
Commodity contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	61	29
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 | Accounts payable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(332)	(264)
Derivative liabilities, Amounts Available for Offset	182	129
Derivative liabilities, Total Net Derivative Instruments	(150)	(135)
Commodity contracts | Accounts payable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(284)	(250)
Commodity contracts | Accounts payable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(48)	(14)
Commodity contracts | Accounts payable and other | 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	(170)	(84)
Derivative liabilities, Amounts Available for Offset	25	13
Derivative liabilities, Total Net Derivative Instruments	(145)	(71)
Commodity contracts | Other long-term liabilities | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(133)	(67)
Commodity contracts | Other long-term liabilities | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative liabilities, Total Gross Derivative Instruments as Presented	(37)	(17)
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
Total net financial asset/(liability)	10	5
Total Net Derivative Instruments	10	5
Other contracts | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	9	5
Other contracts | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	1	0
Other contracts | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Total net financial asset/(liability)	0	0
Other contracts | Accounts receivable and other
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	7	2
Derivative assets, Amounts Available for Offset	0	0
Derivative assets, Total Net Derivative Instruments	7	2
Other contracts | Accounts receivable and other | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	7	2
Other contracts | Accounts receivable and other | Cash flow hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	0	0
Other contracts | Accounts receivable and other | Fair value hedges | Designated as hedging instrument
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	0	0
Other contracts | Deferred amounts and other assets
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	3	3
Derivative assets, Amounts Available for Offset	0	0
Derivative assets, Total Net Derivative Instruments	3	3
Other contracts | Deferred amounts and other assets | Non- Qualifying Derivative Instruments
TOTAL DERIVATIVE INSTRUMENTS
Derivative assets, Total Gross Derivative Instruments as Presented	2	3
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	0
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	$ 0