NONCONTROLLING INTERESTS - REDEEMABLE NONCONTROLLING INFORMATION (Details) $ in Millions		1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 18, 2017 CAD shares	Apr. 30, 2017 USD ($)	Mar. 31, 2017 CAD	Dec. 31, 2017 CAD shares	Dec. 31, 2016 CAD shares	Dec. 31, 2015 CAD shares	Nov. 30, 2017	Apr. 30, 2016	Mar. 31, 2016	Nov. 30, 2015	Oct. 31, 2015
REDEEMABLE NONCONTROLLING INTERESTS
Balance at beginning of year			CAD 3,392,000,000	CAD 3,392,000,000	CAD 2,141,000,000	CAD 2,249,000,000
Earnings/(loss) attributable to redeemable noncontrolling interests				175,000,000	268,000,000	(3,000,000)
Change in unrealized loss on cash flow hedges				(21,000,000)	(17,000,000)	(7,000,000)
Other comprehensive loss from equity investees				0	0	(12,000,000)
Reclassification to earnings of loss on cash flow hedges				57,000,000	9,000,000	4,000,000
Foreign currency translation adjustments				(6,000,000)	(3,000,000)	18,000,000
Other comprehensive income/(loss)				30,000,000	(11,000,000)	3,000,000
Distributions to unitholders				(247,000,000)	(202,000,000)	(114,000,000)
Contributions from unitholders				1,178,000,000	591,000,000	670,000,000
Reversal of cumulative redemption value adjustment attributable to ECT preferred units				0	0	(541,000,000)
Dilution gain/(loss) for redeemable noncontrolling interests				(169,000,000)	(81,000,000)	(482,000,000)
Redemption value adjustment				(292,000,000)	686,000,000	359,000,000
Balance at end of year				4,067,000,000	3,392,000,000	2,141,000,000
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Common shares issued				1,549,000,000	2,260,000,000	57,000,000
Dilution gain/(loss) for redeemable noncontrolling interests				CAD (169,000,000)	CAD (81,000,000)	CAD (482,000,000)
Additional disclosure
Units purchased | shares				1,600,000	1,300,000	0
Enbridge Commercial Trust
REDEEMABLE NONCONTROLLING INTERESTS
Dilution gain/(loss) for redeemable noncontrolling interests				CAD (123,000,000)	CAD (103,000,000)	CAD (132,000,000)
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Dilution gain/(loss) for redeemable noncontrolling interests				(123,000,000)	(103,000,000)	(132,000,000)
Dilution gain/(loss) in Additional paid-in capital				123,000,000	103,000,000	132,000,000
Enbridge Commercial Trust | Enbridge Income Fund
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Proceeds from issuance				CAD 718,000,000	CAD 718,000,000	CAD 874,000,000
Enbridge Income Fund
Additional disclosure
Ownership interest percentage held by noncontrolling owners				56.50%	45.60%	40.70%	53.60%	45.60%	40.70%	40.70%	34.30%
Enbridge Income Fund Holdings Inc | Common Stock Issuance
REDEEMABLE NONCONTROLLING INTERESTS
Dilution gain/(loss) for redeemable noncontrolling interests				CAD 5,000,000	CAD (4,000,000)	CAD (355,000,000)
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Proceeds from issuance				552,000,000	551,000,000	670,000,000
Dilution gain/(loss) for redeemable noncontrolling interests				5,000,000	(4,000,000)	(355,000,000)
Dilution gain/(loss) in Additional paid-in capital				(5,000,000)	4,000,000	355,000,000
Enbridge Income Fund Holdings Inc | Dividend Reinvestment Plan
REDEEMABLE NONCONTROLLING INTERESTS
Dilution gain/(loss) for redeemable noncontrolling interests				0	0	0
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Proceeds from issuance				51	40	0
Dilution gain/(loss) for redeemable noncontrolling interests				0	0	0
Dilution gain/(loss) in Additional paid-in capital				0	0	0
Enbridge Income Fund Holdings Inc | Public investors
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Common shares issued				575,000,000	575,000,000	700,000,000
Enbridge Income Fund Holdings Inc | Enbridge Inc.
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Common shares issued				143,000,000	143,000,000	174,000,000
Secondary Offering By Parent | Enbridge Income Fund Holdings Inc
REDEEMABLE NONCONTROLLING INTERESTS
Dilution gain/(loss) for redeemable noncontrolling interests | $		$ (87)
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Dilution gain/(loss) for redeemable noncontrolling interests | $		$ (87)
Additional disclosure
Sale of stock, percentage of ownership after transaction	19.90%
Sale of stock, number of shares retained by parent (in shares) | shares	4,309,867
Secondary Offering By Parent | Enbridge Income Fund Holdings Inc | Public investors
Additional disclosure
Sale of stock, consideration received by parent	CAD 575,000,000
Secondary Offering By Parent | Enbridge Income Fund Holdings Inc | Enbridge Inc.
Additional disclosure
Stock issued during period, shares, conversion of units (in shares) | shares	21,657,617
Enbridge Income Fund Holdings Inc
Redeemable Noncontrolling Interest, Common Share Issuances [Abstract]
Dilution gain/(loss) in Additional paid-in capital				CAD 41,000,000	CAD 30,000,000	CAD 5,000,000
Additional disclosure
Ownership interest percentage held by noncontrolling owners			45.60%	53.70%
Economic interest (as a percent)	84.60%		86.90%
Ownership interest (as a percent)				19.90%