Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

GOODWILL - NARRATIVE (Details) - CAD ($) $ in Millions		12 Months Ended
GOODWILL - NARRATIVE (Details) - CAD ($) $ in Millions	Jul. 04, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 27, 2017
GOODWILL
Impairment of goodwill		$ 0	$ 1,019	$ 102
Goodwill		$ 33,153	34,459
Spectra Energy Corp
GOODWILL
Goodwill				$ 36,700	$ 36,656
Dispositions \| Midcoast Operating L.P.
GOODWILL
Goodwill, write of due to deconsolidation			262
Dispositions \| Canadian Natural Gas Gathering and Processing Business
GOODWILL
Impairment of goodwill	$ 1,019
Goodwill, write of due to deconsolidation			$ 366