COMPONENTS OF ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - CAD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Changes in AOCI
Balance at the beginning of the period	$ 63,398
Other comprehensive income/(loss) retained in AOCI	380	$ 5,010
Other		16
Total before tax impact	428	5,203
Income tax on amounts retained in AOCI	(118)	(243)
Income tax on amounts reclassified to earnings	(3)	(39)
Tax impact	(121)	(282)
Balance at the end of the period	68,474	67,430
Interest rate contracts
Changes in AOCI
Other comprehensive loss/(income) reclassified to earnings	63	187
Foreign exchange contracts
Changes in AOCI
Other comprehensive loss/(income) reclassified to earnings		(4)
Other contracts
Changes in AOCI
Other comprehensive loss/(income) reclassified to earnings	1	3
Total
Changes in AOCI
Balance at the beginning of the period	3,520	(1,096)
Balance at the end of the period	3,827	3,825
Cash Flow Hedges
Changes in AOCI
Balance at the beginning of the period	121	(897)
Other comprehensive income/(loss) retained in AOCI	447	1,073
Total before tax impact	511	1,259
Income tax on amounts retained in AOCI	(117)	(242)
Income tax on amounts reclassified to earnings	(6)	(41)
Tax impact	(123)	(283)
Balance at the end of the period	509	79
Cash Flow Hedges | Interest rate contracts
Changes in AOCI
Other comprehensive loss/(income) reclassified to earnings	63	187
Cash Flow Hedges | Foreign exchange contracts
Changes in AOCI
Other comprehensive loss/(income) reclassified to earnings		(4)
Cash Flow Hedges | Other contracts
Changes in AOCI
Other comprehensive loss/(income) reclassified to earnings	1	3
Excluded Components of Fair Value Hedges
Changes in AOCI
Balance at the beginning of the period	(35)	0
Other comprehensive income/(loss) retained in AOCI	11	(38)
Total before tax impact	11	(38)
Tax impact	0	0
Balance at the end of the period	(24)	(38)
Net Investment Hedges
Changes in AOCI
Balance at the beginning of the period	(1,137)	(166)
Other comprehensive income/(loss) retained in AOCI	42	(1,187)
Total before tax impact	42	(1,187)
Income tax on amounts retained in AOCI		0
Tax impact	0	0
Balance at the end of the period	(1,095)	(1,353)
Cumulative Translation Adjustment
Changes in AOCI
Balance at the beginning of the period	4,348	56
Other comprehensive income/(loss) retained in AOCI	(128)	5,168
Total before tax impact	(128)	5,168
Tax impact	0	0
Balance at the end of the period	4,220	5,224
Equity Investees
Changes in AOCI
Balance at the beginning of the period	5	(5)
Other comprehensive income/(loss) retained in AOCI	8	(6)
Other		16
Total before tax impact	8	10
Income tax on amounts retained in AOCI	(1)	(1)
Tax impact	(1)	(1)
Balance at the end of the period	12	4
Pension and OPEB Adjustment
Changes in AOCI
Balance at the beginning of the period	218	(84)
Other comprehensive loss/(income) reclassified to earnings	(16)	(9)
Total before tax impact	(16)	(9)
Income tax on amounts reclassified to earnings	3	2
Tax impact	3	2
Balance at the end of the period	$ 205	$ (91)