COMPONENTS OF ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Changes in AOCI
Balance at the beginning of the period	$ 64,483
Other comprehensive income/(loss) retained in AOCI	1,380	$ (125)
Total before tax impact	1,394	(121)
Income tax on amounts retained in AOCI	(30)	28
Income tax on amounts reclassified to earnings	(3)	(1)
Tax impact	(33)	27
Balance at the end of the period	67,303	65,025
Foreign exchange contracts
Changes in AOCI
Other comprehensive (income)/loss reclassified to earnings	19
Interest rate contracts
Changes in AOCI
Other comprehensive (income)/loss reclassified to earnings		8
Other contracts
Changes in AOCI
Other comprehensive (income)/loss reclassified to earnings		1
Total
Changes in AOCI
Balance at the beginning of the period	2,303	3,520
Balance at the end of the period	3,664	3,426
Cash Flow Hedges
Changes in AOCI
Balance at the beginning of the period	320	121
Other comprehensive income/(loss) retained in AOCI	144	(90)
Total before tax impact	144	(81)
Income tax on amounts retained in AOCI	(34)	28
Income tax on amounts reclassified to earnings	0	(2)
Tax impact	(34)	26
Balance at the end of the period	430	66
Cash Flow Hedges | Interest rate contracts
Changes in AOCI
Other comprehensive (income)/loss reclassified to earnings		8
Cash Flow Hedges | Other contracts
Changes in AOCI
Other comprehensive (income)/loss reclassified to earnings		1
Excluded Components of Fair Value Hedges
Changes in AOCI
Balance at the beginning of the period	(23)	(35)
Other comprehensive income/(loss) retained in AOCI	(15)	7
Total before tax impact	4	7
Income tax on amounts retained in AOCI	4
Income tax on amounts reclassified to earnings	(4)
Tax impact	0	0
Balance at the end of the period	(19)	(28)
Excluded Components of Fair Value Hedges | Foreign exchange contracts
Changes in AOCI
Other comprehensive (income)/loss reclassified to earnings	19
Net Investment Hedges
Changes in AOCI
Balance at the beginning of the period	(728)	(1,137)
Other comprehensive income/(loss) retained in AOCI	(377)	15
Total before tax impact	(377)	15
Tax impact	0	0
Balance at the end of the period	(1,105)	(1,122)
Cumulative Translation Adjustment
Changes in AOCI
Balance at the beginning of the period	2,653	4,348
Other comprehensive income/(loss) retained in AOCI	1,629	(57)
Total before tax impact	1,629	(57)
Tax impact	0	0
Balance at the end of the period	4,282	4,291
Equity Investees
Changes in AOCI
Balance at the beginning of the period	11	5
Other comprehensive income/(loss) retained in AOCI	(1)
Total before tax impact	(1)	0
Tax impact	0	0
Balance at the end of the period	10	5
Pension and OPEB Adjustment
Changes in AOCI
Balance at the beginning of the period	70	218
Other comprehensive (income)/loss reclassified to earnings	(5)	(5)
Total before tax impact	(5)	(5)
Income tax on amounts reclassified to earnings	1	1
Tax impact	1	1
Balance at the end of the period	$ 66	$ 214