INCOME TAXES - DEFERRED INCOME TAXES (Details) - CAD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred income tax liabilities
Property, plant and equipment	$ (8,721)	$ (7,786)
Investments	(6,097)	(4,649)
Regulatory assets	(1,245)	(1,156)
Other	(208)	(127)
Total deferred income tax liabilities	(16,271)	(13,718)
Deferred income tax assets
Financial instruments	315	518
Pension and OPEB plans	110	251
Loss carryforwards	3,081	2,005
Other	1,648	1,461
Total deferred income tax assets	5,154	4,235
Less valuation allowance	(84)	(79)
Total deferred income tax assets, net	5,070	4,156
Net deferred income tax liabilities	(11,201)	(9,562)
Deferred income taxes	488	770
Total deferred income tax liabilities	(11,689)	(10,332)
Operating loss carryforwards that do not expire	7,500	3,400
Foreign subsidiaries' undistributed earnings on which deferred income taxes has not been provided	4,300	5,500
Canada
Deferred income tax assets
Benefit of unused tax loss carryforwards recognized	1,900	2,600
US
Deferred income tax assets
Benefit of unused tax loss carryforwards recognized	11,000	5,800
Operating loss carryforwards that expire	$ 3,500	$ 2,400