SEGMENTED INFORMATION (Details) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segmented Information
Revenues	$ 11,345	$ 9,227	$ 34,816	$ 31,489
Commodity and gas distribution costs	(7,017)	(5,302)	(22,037)	(19,785)
Operating and administrative	(1,652)	(1,587)	(4,929)	(4,784)
Asset impairment	(4)	0	(1,076)	0
Goodwill impairment (Note 6)	(1,019)	0	(1,019)	0
Income/(loss) from equity investments	378	280	1,076	752
Other	24	225	(110)	439
Earnings/(loss) before interest and income taxes	2,055	2,843	6,721	8,111
Depreciation and amortization	(799)	(848)	(2,452)	(2,388)
Interest expense	(696)	(653)	(2,042)	(1,704)
Income tax recovery/(expense)	(347)	(327)	(177)	(818)
Earnings	213	1,015	2,050	3,201
Capital expenditures	1,362	1,969	4,633	5,982
Consolidation, Eliminations
Segmented Information
Revenues	(120)	(68)	(390)	(264)
Commodity and gas distribution costs	121	68	392	268
Operating and administrative	(25)	(20)	(182)	(432)
Asset impairment	0		(5)
Goodwill impairment (Note 6)	0		0
Income/(loss) from equity investments	0	0	0	(4)
Other	53	146	(183)	244
Earnings/(loss) before interest and income taxes	29	126	(368)	(188)
Capital expenditures	(19)	22	(11)	90
Liquids Pipelines | Business segments
Segmented Information
Revenues	2,529	2,324	6,388	6,722
Commodity and gas distribution costs	(5)	(5)	(14)	(13)
Operating and administrative	(790)	(770)	(2,251)	(2,214)
Asset impairment	0		(154)
Goodwill impairment (Note 6)	0		0
Income/(loss) from equity investments	131	118	399	312
Other	10	36	(15)	33
Earnings/(loss) before interest and income taxes	1,875	1,703	4,353	4,840
Capital expenditures	651	529	1,776	1,723
Gas Transmission and Midstream | Business segments
Segmented Information
Revenues	1,528	1,862	5,329	5,051
Commodity and gas distribution costs	(270)	(703)	(1,481)	(2,053)
Operating and administrative	(519)	(498)	(1,560)	(1,305)
Asset impairment	0		(913)
Goodwill impairment (Note 6)	(1,019)		(1,019)
Income/(loss) from equity investments	262	162	699	427
Other	(42)	33	25	143
Earnings/(loss) before interest and income taxes	(60)	856	1,080	2,263
Capital expenditures	413	1,052	2,105	3,081
Gas Distribution | Business segments
Segmented Information
Revenues	645	716	3,952	3,322
Commodity and gas distribution costs	(137)	(242)	(1,969)	(1,740)
Operating and administrative	(263)	(246)	(782)	(676)
Asset impairment	0		0
Goodwill impairment (Note 6)	0		0
Income/(loss) from equity investments	(12)	(3)	(5)	10
Other	23	15	66	21
Earnings/(loss) before interest and income taxes	256	240	1,262	937
Capital expenditures	311	302	733	794
Green Power and Transmission | Business segments
Segmented Information
Revenues	117	109	423	386
Commodity and gas distribution costs	0	1	0	4
Operating and administrative	(38)	(42)	(104)	(123)
Asset impairment	(4)		(4)
Goodwill impairment (Note 6)	0		0
Income/(loss) from equity investments	(6)	0	(27)	2
Other	(18)	0	(2)	1
Earnings/(loss) before interest and income taxes	51	68	286	270
Capital expenditures	6	64	30	293
Energy Services | Business segments
Segmented Information
Revenues	6,646	4,284	19,114	16,272
Commodity and gas distribution costs	(6,726)	(4,421)	(18,965)	(16,251)
Operating and administrative	(17)	(11)	(50)	(34)
Asset impairment	0		0
Goodwill impairment (Note 6)	0		0
Income/(loss) from equity investments	3	3	10	5
Other	(2)	(5)	(1)	(3)
Earnings/(loss) before interest and income taxes	(96)	(150)	108	(11)
Capital expenditures	$ 0	$ 0	$ 0	$ 1