ACQUISITIONS AND DISPOSITIONS - Schedule of Supplemental Pro Forma Consolidated Financial Information (Details) - Moda Midstream Operating, LLC (Moda) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Operating revenues	$ 47,339	$ 39,435
Earnings attributable to common shareholders	5,771	2,938
Acquisition-related expenses	21
Acquisition-related expenses, after tax	16
Amortization of fair value adjustments recorded for acquired property, plant and equipment, long-term investments and intangible assets	193	207
Amortization of fair value adjustments recorded for acquired property, plant and equipment, long-term investments and intangible assets, after tax	$ 145	$ 155