ACQUISITIONS AND DISPOSITIONS - Dispositions (Narrative) (Details)				12 Months Ended
	Jun. 01, 2020 CAD ($)	May 01, 2020 CAD ($)	Apr. 01, 2020 CAD ($)	Dec. 31, 2022 CAD ($)	Oct. 05, 2022 CAD ($) _community pipeline
Athabasca Indigenous Investments Limited Partnership
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of communities represented | _community					23
Athabasca Regional Oil Sands System
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of pipelines to be sold | pipeline					7
Disposal group, consideration					$ 1,100,000,000
Athabasca Regional Oil Sands System | Athabasca Regional Oil Sands System
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest percentage held by noncontrolling owners					11.60%
Noncontrolling interest (percent)					88.40%
Dispositions | Line 10 Crude Oil
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest	$ 0
Dispositions | Ozark Pipeline
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest			$ 1,000,000
Cash proceeds from sale of interest			$ 63,000,000
Dispositions | Athabasca Regional Oil Sands System
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest				$ 0
Dispositions | Montana-Alberta Tie Line (MATL)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest		$ 4,000,000
Cash proceeds from sale of interest		$ 189,000,000