REVENUE - Major Products and Services (Details) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 5,733	$ 5,171	$ 18,438	$ 17,976
Total revenue	14,882	9,844	37,256	32,351
Realized gain/(loss) on derivative	54	(97)	15	(149)
Revenues from lease contracts	125	107	407	387
Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,617	4,298	14,078	13,361
Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	333	266	959	784
Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	710	528	3,149	3,611
Total revenue	702	516	3,181	3,587
Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	36	79	137	220
Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	37		115
Revenue not from contract with customers	8,949	4,652	18,307	14,114
Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	200	21	511	261
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,971	2,921	9,108	8,991
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,444	1,412	4,426	4,294
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,282	759	4,767	4,471
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	36	79	137	220
Business segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,971	2,921	9,108	8,991
Total revenue	11,775	7,355	26,815	22,200
Business segments | Liquids Pipelines | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,906	2,856	8,916	8,800
Business segments | Liquids Pipelines | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	65	65	192	191
Business segments | Liquids Pipelines | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Liquids Pipelines | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Liquids Pipelines | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0		0
Revenue not from contract with customers	8,725	4,373	17,494	13,039
Business segments | Liquids Pipelines | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	79	61	213	170
Business segments | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,444	1,412	4,426	4,294
Total revenue	1,486	1,423	4,550	4,324
Business segments | Gas Transmission | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,264	1,294	3,895	3,968
Business segments | Gas Transmission | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	143	118	416	326
Business segments | Gas Transmission | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Gas Transmission | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Gas Transmission | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	37		115
Revenue not from contract with customers	10	0	62	0
Business segments | Gas Transmission | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	27	11	46	29
Business segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,282	759	4,767	4,471
Total revenue	1,281	751	4,796	4,426
Business segments | Gas Distribution and Storage | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	447	148	1,267	593
Business segments | Gas Distribution and Storage | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	125	83	351	267
Business segments | Gas Distribution and Storage | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	710	528	3,149	3,611
Business segments | Gas Distribution and Storage | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Gas Distribution and Storage | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0		0
Revenue not from contract with customers	0	0	0	0
Business segments | Gas Distribution and Storage | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	(2)	(9)	24	(50)
Business segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	36	79	137	220
Total revenue	133	40	370	334
Business segments | Renewable Power Generation | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Renewable Power Generation | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Renewable Power Generation | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business segments | Renewable Power Generation | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	36	79	137	220
Business segments | Renewable Power Generation | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0		0
Revenue not from contract with customers	0	0	0	0
Business segments | Renewable Power Generation | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	96	(42)	228	112
Eliminations and Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Total revenue	207	275	725	1,067
Eliminations and Other | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Eliminations and Other | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Eliminations and Other | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Eliminations and Other | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Eliminations and Other | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0		0
Revenue not from contract with customers	214	279	751	1,075
Eliminations and Other | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0	0	0
Intersegment revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	(7)	(4)	(26)	(8)
Total revenue	207	275	725	1,067
Intersegment revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0	0	0
Intersegment revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	5	0	16	1
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	1	1	5	5
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	$ 1	$ 3	$ 5	$ 2