AQUISITIONS AND DISPOSITIONS (Details) € in Millions, $ in Millions, $ in Millions				3 Months Ended		9 Months Ended
	Aug. 01, 2018 CAD ($)	Aug. 01, 2018 USD ($)	Aug. 01, 2018 EUR (€)	Sep. 30, 2018 CAD ($)	Sep. 30, 2017 CAD ($)	Sep. 30, 2018 CAD ($)	Sep. 30, 2017 CAD ($)	Jun. 30, 2019 CAD ($)	Sep. 30, 2018 USD ($)	Aug. 01, 2018 USD ($)	Jul. 04, 2018 CAD ($)	Jun. 30, 2018 CAD ($)	Dec. 31, 2017 CAD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill impairment				$ 1,019	$ 0	$ 1,019	$ 0
Deferred income tax recovery						51	$ (725)
Goodwill				33,477		33,477							$ 34,457
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities				430		430							$ 34
Disposal Group, Held-for-sale, Not Discontinued Operations | 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
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]
Carrying amount of investment												$ 447
Goodwill												$ 262
Disposed of by sale, not discontinued operations | Canadian Renewable Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal	$ 62
Disposed of by sale, not discontinued operations | United States Renewable Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal	17	$ 13
Asset Impairment | Disposal Group, Held-for-sale, Not Discontinued Operations | Line 10 Crude Oil Pipeline
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision for loss (gain) on disposal, before income tax						154
Provision for loss (gain) on disposal, net of tax						95
Asset Impairment | Disposal Group, Held-for-sale, Not Discontinued Operations | Midcoast Operating L.P.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision for loss (gain) on disposal, before income tax						913
Provision for loss (gain) on disposal, net of tax						701
Other Nonoperating Income (Expense) | Disposed of by sale, not discontinued operations | Hohe See Offshore Wind Project
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal	20		€ 14
Enbridge (U.S.) Inc. | Disposed of by sale, not discontinued operations | Midcoast Operating L.P.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, consideration	1,400									$ 1,100
Gain (loss) on disposal	74	$ 57
Liabilities	$ 387									$ 298
Scenario, Forecast | Disposed of by sale, not discontinued operations | 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								$ 1,800
Hohe See Offshore Wind Project | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest in equity investment (as a percent)	49.00%									49.00%
The Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of equity method investments	$ 1,750
Deferred income tax recovery						196
The Assets | Renewable Energy Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred income tax recovery						267
Canadian Renewable Assets | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest, ownership percentage by parent	49.00%									49.00%
United States Renewable Assets | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest, ownership percentage by parent	49.00%									49.00%
Renewable Energy Assets | The Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest, ownership percentage by parent	51.00%									51.00%
Accounts payable and other | Enbridge (U.S.) Inc. | Disposed of by sale, not discontinued operations | Midcoast Operating L.P.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities				75		75			$ 58
Other Long-Term Liabilities | Enbridge (U.S.) Inc. | Disposed of by sale, not discontinued operations | Midcoast Operating L.P.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities				$ 306		$ 306			$ 237