SEGMENTED INFORMATION (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segmented Information
Revenues	$ 12,856	$ 12,726
Commodity and gas distribution costs	(7,772)	(8,321)
Operating and administrative	(1,625)	(1,641)
Asset impairment	0	(1,062)
Income/(loss) from equity investments	413	335
Other	260	(120)
Earnings/(loss) before interest and income taxes	4,132	1,917
Depreciation and amortization	(840)	(824)
Interest expense	(685)	(656)
Income tax recovery/(expense)	(584)	73
Earnings	2,023	510
Capital expenditures	1,627	1,643
Intersegment Eliminations
Segmented Information
Revenues	(136)	(146)
Commodity and gas distribution costs	128	146
Operating and administrative	58	(97)
Asset impairment		(5)
Income/(loss) from equity investments	1	0
Other	197	(177)
Earnings/(loss) before interest and income taxes	248	(279)
Capital expenditures	25	6
Liquids Pipelines | Business segments
Segmented Information
Revenues	2,658	1,909
Commodity and gas distribution costs	(6)	(4)
Operating and administrative	(801)	(747)
Asset impairment		(144)
Income/(loss) from equity investments	197	131
Other	24	11
Earnings/(loss) before interest and income taxes	2,072	1,156
Capital expenditures	1,020	615
Gas Transmission and Midstream | Business segments
Segmented Information
Revenues	1,318	1,937
Commodity and gas distribution costs	0	(620)
Operating and administrative	(513)	(507)
Asset impairment		(913)
Income/(loss) from equity investments	197	208
Other	18	21
Earnings/(loss) before interest and income taxes	1,020	126
Capital expenditures	394	825
Gas Distribution | Business segments
Segmented Information
Revenues	2,191	2,237
Commodity and gas distribution costs	(1,264)	(1,388)
Operating and administrative	(294)	(248)
Asset impairment		0
Income/(loss) from equity investments	11	17
Other	18	18
Earnings/(loss) before interest and income taxes	662	636
Capital expenditures	173	183
Renewable Power Generation and Transmission | Business segments
Segmented Information
Revenues	152	157
Commodity and gas distribution costs	(1)	0
Operating and administrative	(42)	(30)
Asset impairment		0
Income/(loss) from equity investments	14	(25)
Other	1	7
Earnings/(loss) before interest and income taxes	124	109
Capital expenditures	14	14
Energy Services | Business segments
Segmented Information
Revenues	6,673	6,632
Commodity and gas distribution costs	(6,629)	(6,455)
Operating and administrative	(33)	(12)
Asset impairment		0
Income/(loss) from equity investments	(7)	4
Other	2	0
Earnings/(loss) before interest and income taxes	6	169
Capital expenditures	$ 1	$ 0