SEGMENTED INFORMATION (Details) - CAD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segmented Information
Revenues	$ 12,470	$ 11,466	$ 10,948	$ 12,187	$ 10,008	$ 9,110	$ 7,956	$ 12,013	$ 47,071	$ 39,087	$ 50,069
Commodity and gas distribution costs									(28,702)	(20,669)	(31,004)
Operating and administrative									(6,712)	(6,749)	(6,991)
Income/(loss) from equity investments									1,711	1,136	1,503
Impairment of equity investments									(111)	(2,351)	0
Other income/(expense)									979	238	435
Impairment of long-lived assets											(423)
Earnings/(loss) before interest, income tax expense and depreciation and amortization									14,236	10,692	13,589
Depreciation and amortization									(3,852)	(3,712)	(3,391)
Interest expense									(2,655)	(2,790)	(2,663)
Income tax expense									(1,415)	(774)	(1,708)
Earnings									6,314	3,416	5,827
Capital expenditures									7,885	5,470	5,550
Property, plant and equipment, net (Note 11)	100,067				94,571				100,067	94,571	93,723
Business segments | Liquids Pipelines
Segmented Information
Revenues									10,581	10,423	10,219
Commodity and gas distribution costs									(25)	(20)	(29)
Operating and administrative									(3,431)	(3,331)	(3,298)
Income/(loss) from equity investments									759	558	780
Impairment of equity investments									0	0
Other income/(expense)									13	53	30
Impairment of long-lived assets											(21)
Earnings/(loss) before interest, income tax expense and depreciation and amortization									7,897	7,683	7,681
Capital expenditures									4,051	2,033	2,548
Property, plant and equipment, net (Note 11)	52,530				48,799				52,530	48,799	48,783
Business segments | Gas Transmission and Midstream
Segmented Information
Revenues									4,711	4,870	5,207
Commodity and gas distribution costs									0	0	0
Operating and administrative									(1,877)	(1,859)	(2,232)
Income/(loss) from equity investments									813	479	682
Impairment of equity investments									(111)	(2,351)
Other income/(expense)									135	(52)	(181)
Impairment of long-lived assets											(105)
Earnings/(loss) before interest, income tax expense and depreciation and amortization									3,671	1,087	3,371
Capital expenditures									2,420	2,130	1,753
Property, plant and equipment, net (Note 11)	27,028				25,745				27,028	25,745	25,268
Business segments | Gas Distribution and Storage
Segmented Information
Revenues									4,980	4,569	5,179
Commodity and gas distribution costs									(2,147)	(1,810)	(2,354)
Operating and administrative									(1,143)	(1,091)	(1,149)
Income/(loss) from equity investments									42	9	4
Impairment of equity investments									0	0
Other income/(expense)									385	71	67
Impairment of long-lived assets											0
Earnings/(loss) before interest, income tax expense and depreciation and amortization									2,117	1,748	1,747
Capital expenditures									1,343	1,134	1,100
Property, plant and equipment, net (Note 11)	16,904				16,079				16,904	16,079	15,622
Business segments | Renewable Power Generation
Segmented Information
Revenues									512	587	567
Commodity and gas distribution costs									0	(2)	(2)
Operating and administrative									(180)	(191)	(189)
Income/(loss) from equity investments									101	94	31
Impairment of equity investments									0	0
Other income/(expense)									75	35	1
Impairment of long-lived assets											(297)
Earnings/(loss) before interest, income tax expense and depreciation and amortization									508	523	111
Capital expenditures									16	81	23
Property, plant and equipment, net (Note 11)	3,315				3,495				3,315	3,495	3,658
Business segments | Energy Services
Segmented Information
Revenues									26,917	19,283	29,374
Commodity and gas distribution costs									(27,174)	(19,450)	(29,091)
Operating and administrative									(48)	(67)	(44)
Income/(loss) from equity investments									0	(3)	8
Impairment of equity investments									0	0
Other income/(expense)									(8)	1	3
Impairment of long-lived assets											0
Earnings/(loss) before interest, income tax expense and depreciation and amortization									(313)	(236)	250
Capital expenditures									1	2	2
Property, plant and equipment, net (Note 11)	23				24				23	24	24
Eliminations and Other
Segmented Information
Revenues									(630)	(645)	(477)
Commodity and gas distribution costs									644	613	472
Operating and administrative									(33)	(210)	(79)
Income/(loss) from equity investments									(4)	(1)	(2)
Impairment of equity investments									0	0
Other income/(expense)									379	130	515
Impairment of long-lived assets											0
Earnings/(loss) before interest, income tax expense and depreciation and amortization									356	(113)	429
Capital expenditures									54	90	124
Property, plant and equipment, net (Note 11)	$ 267				$ 429				$ 267	$ 429	$ 368
Customer Concentration Risk | Sales Revenue, Net | Largest Non-Affiliated Customer
Narrative
Concentration (percent)									13.50%	13.60%