INCOME TAXES - Deferred Income Tax Assets and Liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred income tax liabilities
Property, plant and equipment	$ (9,202)	$ (9,096)
Investments	(7,765)	(7,099)
Regulatory assets	(1,338)	(1,291)
Other	(52)	(46)
Total deferred income tax liabilities	(18,357)	(17,532)
Deferred income tax assets
Financial instruments	271	456
Loss carryforwards	1,745	2,259
Other	1,798	1,723
Total deferred income tax assets	3,814	4,438
Less valuation allowance	(147)	(215)
Total deferred income tax assets, net	3,667	4,223
Net deferred income tax liabilities	(14,690)	(13,309)
Total deferred income tax assets	341	472
Total deferred income tax liabilities	$ (15,031)	$ (13,781)