ACQUISITIONS - Summary of Estimated Fair Values Assigned to Net Assets (Details) $ in Millions, $ in Millions	Mar. 06, 2024 CAD ($)	Mar. 06, 2024 USD ($)	Jan. 02, 2024 CAD ($) promissoryNote	Jan. 02, 2024 USD ($)	Mar. 31, 2024 CAD ($)	Jan. 02, 2024 USD ($) promissoryNote	Dec. 31, 2023 CAD ($)
Fair value of net assets acquired:
Goodwill					$ 34,294		$ 31,848
EOG Acquisition
Fair value of net assets acquired:
Current assets	$ 641
Property, plant and equipment	7,253
Long-term assets	1,647
Current liabilities	670
Long-term debt	2,612
Other long-term liabilities	993
Deferred income tax liabilities	1,036
Goodwill	1,608
Purchase price:
Cash	5,838
Deferred consideration
Purchase price	5,800	$ 4,300
Expected credit	3
Overfunded pension plan assets	395
Regulatory assets	1,200
Fair value adjustment of long-term debt	478
EOG Acquisition | Carrying value
Fair value of net assets acquired:
Current assets	$ 376
RNG Facilities
Fair value of net assets acquired:
Current assets			$ 31
Intangible assets			925
Property, plant and equipment			174
Current liabilities			5
Goodwill			223
Purchase price:
Cash			584	$ 439
Deferred consideration
Current portion of long-term debt			550
Long-term debt			207
Other adjustments			7
Purchase price			$ 1,348	$ 1,000
Goodwill expected tax deductible period (in years)			15 years	15 years
Number of non-interest promissory notes | promissoryNote			6			6
Remaining consideration payable, payment period (in years)			2 years	2 years
Consideration transferred, liabilities incurred			$ 757	$ 568
RNG Facilities | Non-Interest Bearing Promissory Notes | Notes Payable, Other Payables
Deferred consideration
Deferred payments			$ 808			$ 606
RNG Facilities | Minimum
Deferred consideration
Amortized on a straight-line basis over term (in years)			13 years	13 years
RNG Facilities | Maximum
Deferred consideration
Amortized on a straight-line basis over term (in years)			42 years	42 years