REVENUES - Disaggregation of Revenue (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 7,213	$ 6,487
Total revenues	12,075	15,097
Mark-to-market (loss) gain from hedging program	(55)	94
Revenues from lease contracts	144	164
Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30	16
Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,183	6,471
Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,602	4,130
Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	258	182
Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		15
Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,287	2,098
Total revenues	2,279	2,098
Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	62
Commodity sales
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	4,783	8,325
Total revenues	4,783	8,325
Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	79	285
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,006	2,736
Liquids Pipelines | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Liquids Pipelines | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,006	2,736
Gas Transmission and Midstream
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,479	1,293
Gas Transmission and Midstream | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Gas Transmission and Midstream | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,479	1,293
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,662	2,396
Gas Distribution and Storage | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30	16
Gas Distribution and Storage | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,632	2,380
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	62
Renewable Power Generation | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Renewable Power Generation | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	62
Business segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,006	2,736
Total revenues	3,165	3,055
Business segments | Liquids Pipelines | Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,942	2,685
Business segments | Liquids Pipelines | Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	64	51
Business segments | Liquids Pipelines | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		0
Business segments | Liquids Pipelines | Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Liquids Pipelines | Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Liquids Pipelines | Commodity sales
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0
Business segments | Liquids Pipelines | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	30	178
Business segments | Gas Transmission and Midstream
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,479	1,293
Total revenues	1,491	1,300
Business segments | Gas Transmission and Midstream | Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,384	1,194
Business segments | Gas Transmission and Midstream | Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	95	84
Business segments | Gas Transmission and Midstream | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		15
Business segments | Gas Transmission and Midstream | Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Gas Transmission and Midstream | Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Gas Transmission and Midstream | Commodity sales
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0
Business segments | Gas Transmission and Midstream | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	11	7
Business segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,662	2,396
Total revenues	2,625	2,411
Business segments | Gas Distribution and Storage | Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	276	251
Business segments | Gas Distribution and Storage | Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	99	47
Business segments | Gas Distribution and Storage | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		0
Business segments | Gas Distribution and Storage | Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,287	2,098
Business segments | Gas Distribution and Storage | Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Gas Distribution and Storage | Commodity sales
Disaggregation of Revenue [Line Items]
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	(40)	4
Business segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	62
Total revenues	144	156
Business segments | Renewable Power Generation | Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Renewable Power Generation | Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Renewable Power Generation | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		0
Business segments | Renewable Power Generation | Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Renewable Power Generation | Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	66	62
Business segments | Renewable Power Generation | Commodity sales
Disaggregation of Revenue [Line Items]
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	78	94
Business segments | Energy Services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Total revenues	4,801	8,337
Business segments | Energy Services | Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Energy Services | Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Energy Services | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		0
Business segments | Energy Services | Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Energy Services | Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business segments | Energy Services | Commodity sales
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	4,783	8,325
Business segments | Energy Services | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	2
Eliminations and Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Total revenues	(151)	(162)
Eliminations and Other | Transportation revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Eliminations and Other | Storage and other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Eliminations and Other | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		0
Eliminations and Other | Gas distribution sales
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Eliminations and Other | Electricity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Eliminations and Other | Commodity sales
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0
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	(151)	(162)
Total revenues	(151)	(162)
Intersegment revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	129	141
Intersegment revenue | Gas Transmission and Midstream
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	1	0
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	3	11
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	0	0
Intersegment revenue | Energy Services
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	$ 18	$ 10