SEGMENTED INFORMATION (Details) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segmented Information
Revenues	$ 11,466	$ 9,110	$ 34,551	$ 29,079
Commodity and gas distribution costs	(7,467)	(4,526)	(21,334)	(15,652)
Operating and administrative	(1,667)	(1,554)	(4,710)	(4,955)
Income/(loss) from equity investments	440	315	1,187	805
Impairment of equity investments	(111)	(615)	(111)	(2,351)
Other income/(expense)	(56)	258	446	(265)
Earnings/(loss) before interest, income taxes, and depreciation and amortization	2,605	2,988	10,029	6,661
Depreciation and amortization	(944)	(935)	(2,805)	(2,766)
Interest expense	(648)	(718)	(1,923)	(2,105)
Income tax expense	(199)	(231)	(952)	(273)
Earnings	814	1,104	4,349	1,517
Capital expenditures	2,033	1,457	5,532	3,836
Eliminations and Other
Segmented Information
Revenues	(162)	(168)	(468)	(473)
Commodity and gas distribution costs	159	179	479	451
Operating and administrative	41	4	(35)	(143)
Income/(loss) from equity investments	0	0	0	0
Impairment of equity investments	0	0	0	0
Other income/(expense)	(159)	192	215	(333)
Earnings/(loss) before interest, income taxes, and depreciation and amortization	(121)	207	191	(498)
Capital expenditures	18	22	39	63
Liquids Pipelines | Business segments
Segmented Information
Revenues	2,370	2,773	7,616	7,252
Commodity and gas distribution costs	(6)	(5)	(16)	(13)
Operating and administrative	(919)	(811)	(2,411)	(2,458)
Income/(loss) from equity investments	226	118	560	463
Impairment of equity investments	0	0	0	0
Other income/(expense)	2	15	7	36
Earnings/(loss) before interest, income taxes, and depreciation and amortization	1,673	2,090	5,756	5,280
Capital expenditures	1,053	442	2,976	1,503
Gas Transmission and Midstream | Business segments
Segmented Information
Revenues	1,159	1,162	3,501	3,722
Commodity and gas distribution costs	0	0	0	0
Operating and administrative	(445)	(432)	(1,303)	(1,377)
Income/(loss) from equity investments	211	191	525	284
Impairment of equity investments	(111)	(615)	(111)	(2,351)
Other income/(expense)	70	28	113	(48)
Earnings/(loss) before interest, income taxes, and depreciation and amortization	884	334	2,725	230
Capital expenditures	602	642	1,631	1,462
Gas Distribution and Storage | Business segments
Segmented Information
Revenues	687	621	3,463	3,206
Commodity and gas distribution costs	(135)	(87)	(1,392)	(1,213)
Operating and administrative	(280)	(243)	(794)	(761)
Income/(loss) from equity investments	(12)	(13)	37	2
Impairment of equity investments	0	0	0	0
Other income/(expense)	22	20	60	51
Earnings/(loss) before interest, income taxes, and depreciation and amortization	282	298	1,374	1,285
Capital expenditures	359	339	878	765
Renewable Power Generation | Business segments
Segmented Information
Revenues	122	126	371	429
Commodity and gas distribution costs	0	0	0	0
Operating and administrative	(51)	(57)	(131)	(144)
Income/(loss) from equity investments	15	22	65	59
Impairment of equity investments	0	0	0	0
Other income/(expense)	5	2	57	32
Earnings/(loss) before interest, income taxes, and depreciation and amortization	91	93	362	376
Capital expenditures	0	11	7	41
Energy Services | Business segments
Segmented Information
Revenues	7,290	4,596	20,068	14,943
Commodity and gas distribution costs	(7,485)	(4,613)	(20,405)	(14,877)
Operating and administrative	(13)	(15)	(36)	(72)
Income/(loss) from equity investments	0	(3)	0	(3)
Impairment of equity investments	0	0	0	0
Other income/(expense)	4	1	(6)	(3)
Earnings/(loss) before interest, income taxes, and depreciation and amortization	(204)	(34)	(379)	(12)
Capital expenditures	$ 1	$ 1	$ 1	$ 2