DISPOSITIONS - Dispositions (Narrative) (Details) $ in Millions										12 Months Ended
	Jun. 01, 2020 CAD ($)	May 01, 2020 CAD ($)	Apr. 01, 2020 CAD ($)	Dec. 31, 2019 CAD ($)	Nov. 01, 2019 CAD ($)	Oct. 01, 2019 CAD ($)	Oct. 01, 2019 USD ($)	Oct. 01, 2018 CAD ($)	Aug. 01, 2018 CAD ($)	Dec. 31, 2020 CAD ($)	Dec. 31, 2019 CAD ($)	Dec. 31, 2018 CAD ($)	Jul. 04, 2018 CAD ($)	Jun. 30, 2018 CAD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of goodwill										$ 0	$ 0	$ 1,019,000,000
Deferred income tax expense/(recovery) (Note 25)										447,000,000	1,156,000,000	(148,000,000)
Impairment loss											423,000,000	1,104,000,000
Goodwill				$ 33,153,000,000						32,688,000,000	33,153,000,000	34,459,000,000
Gain on disposal of assets										6,000,000	(254,000,000)	(8,000,000)
Liquids Pipelines
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill				7,951,000,000						$ 7,828,000,000	7,951,000,000	8,324,000,000
Disposal group, held-for-sale, not discontinued operations | Montana-Alberta Tie Line (MATL)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of long-lived assets to be disposed of											297,000,000
Disposal group, held-for-sale, not discontinued operations | Texas Express Ngl System
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity investment														$ 447,000,000
Goodwill														$ 262,000,000
Disposal group, held-for-sale, not discontinued operations | 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 | 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
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 | St. Lawrence Gas
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest											(10,000,000)
Cash proceeds from sale of interest					$ 72,000,000
Dispositions | Enbridge Gas New Brunswick
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest						$ (3,000,000)
Cash proceeds from sale of interest							$ 331
Goodwill included in assets subsequently disposed						$ 133,000,000
Dispositions | Canadian Natural Gas Gathering and Processing Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration													$ 4,300,000,000
Impairment of goodwill												1,000,000,000.0
Dispositions | Canadian Renewable Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest												62,000,000
Dispositions | United States Renewable Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest												17,000,000
Dispositions | Liquids Pipelines | Sandpiper
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from sale of assets												38,000,000
Gain on disposal of assets												29,000,000
Other income/(expense) | Dispositions | Hohe See Offshore Wind Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest												(20,000,000)
Asset Impairment | Disposal group, held-for-sale, not discontinued operations | Line 10 Crude Oil
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operation, provision for loss (gain) on disposal, before income tax												$ 154,000,000
Canadian Renewable Assets | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest (percent)									49.00%			49.00%
United States Renewable Assets | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest (percent)									49.00%
Provincially Regulated Facilities | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill included in assets subsequently disposed												$ 366,000,000
Cash proceeds from sale of assets								$ 2,500,000,000
Gain on disposal of assets												34,000,000
Federally Regulated Facilities | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill included in assets subsequently disposed												55,000,000
Cash proceeds from sale of assets				1,700,000,000
Gain on disposal of assets											(268,000,000)
Hohe See Offshore Wind Project | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest of equity method investment (as a percent)									49.00%
The Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred income tax expense/(recovery) (Note 25)												(196,000,000)
The Assets | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of equity method investments									$ 1,750,000,000
The Assets | Renewable energy assets | Dispositions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest (percent)										51.00%
Renewable energy assets | The Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred income tax expense/(recovery) (Note 25)												(267,000,000)
Enbridge (U.S.) Inc. | Dispositions | Midcoast Operating L.P.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal of interest									(41,000,000)
Disposal group, consideration									1,400,000,000
Impairment loss												$ 913,000,000
Other long-term liabilities (long-term liabilities held for sale)				$ 299,000,000					$ 387,000,000	$ 225,000,000	$ 299,000,000