REVENUE - Major Products and Services (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 6,778	$ 7,213
Total revenue	11,038	12,075
Realized loss on derivative	22	55
Revenues from lease contracts	140	144
Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,716	4,602
Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	299	258
Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,666	2,287
Total revenue	1,699	2,279
Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	66
Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40
Revenue not from contract with customers	4,105	4,783
Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	155	79
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,086	3,006
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,519	1,479
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,116	2,662
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	66
Business segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,086	3,006
Total revenue	6,882	7,298
Business segments | Liquids Pipelines | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,024	2,942
Business segments | Liquids Pipelines | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	62	64
Business segments | Liquids Pipelines | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Liquids Pipelines | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Liquids Pipelines | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
Revenue not from contract with customers	3,733	4,262
Business segments | Liquids Pipelines | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	63	30
Business segments | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,519	1,479
Total revenue	1,572	1,491
Business segments | Gas Transmission | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,341	1,384
Business segments | Gas Transmission | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	138	95
Business segments | Gas Transmission | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Gas Transmission | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Gas Transmission | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40
Revenue not from contract with customers	41	0
Business segments | Gas Transmission | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	6	11
Business segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,116	2,662
Total revenue	2,131	2,625
Business segments | Gas Distribution and Storage | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	351	276
Business segments | Gas Distribution and Storage | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	99	99
Business segments | Gas Distribution and Storage | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,666	2,287
Business segments | Gas Distribution and Storage | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Gas Distribution and Storage | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
Revenue not from contract with customers	0	0
Business segments | Gas Distribution and Storage | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	13	(40)
Business segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	66
Total revenue	131	144
Business segments | Renewable Power Generation | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Renewable Power Generation | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Renewable Power Generation | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business segments | Renewable Power Generation | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	66
Business segments | Renewable Power Generation | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
Revenue not from contract with customers	0	0
Business segments | Renewable Power Generation | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	73	78
Eliminations and Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Total revenue	322	517
Eliminations and Other | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Eliminations and Other | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Eliminations and Other | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Eliminations and Other | Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Eliminations and Other | Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0
Revenue not from contract with customers	331	521
Eliminations and Other | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0
Intersegment revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	(9)	(4)
Intersegment revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0
Intersegment revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	6	1
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	2	3
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	$ 1	$ 0