REVENUE - Major Products and Services (Details) - CAD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 5,927	$ 5,592	$ 12,705	$ 12,805
Total revenue	11,336	10,432	22,374	22,507
Realized (loss) gain on derivative	(17)	3	(39)	(52)
Revenues from lease contracts	142	136	282	280
Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,745	4,461	9,461	9,063
Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	327	260	626	518
Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	773	796	2,439	3,083
Total revenue	780	792	2,479	3,071
Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	44	75	101	141
Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	38		78
Revenue not from contract with customers	5,253	4,679	9,358	9,462
Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	156	161	311	240
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,051	3,064	6,137	6,070
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,463	1,403	2,982	2,882
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,369	1,050	3,485	3,712
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	44	75	101	141
Business segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,051	3,064	6,137	6,070
Total revenue	8,158	7,547	15,040	14,845
Business segments | Liquids Pipelines | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,986	3,002	6,010	5,944
Business segments | Liquids Pipelines | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	65	62	127	126
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
Revenue not from contract with customers	5,036	4,404	8,769	8,666
Business segments | Liquids Pipelines | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	71	79	134	109
Business segments | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,463	1,403	2,982	2,882
Total revenue	1,492	1,410	3,064	2,901
Business segments | Gas Transmission | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,290	1,290	2,631	2,674
Business segments | Gas Transmission | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	135	113	273	208
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	38		78
Revenue not from contract with customers	11	0	52	0
Business segments | Gas Transmission | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	13	7	19	18
Business segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,369	1,050	3,485	3,712
Total revenue	1,384	1,050	3,515	3,675
Business segments | Gas Distribution and Storage | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	469	169	820	445
Business segments | Gas Distribution and Storage | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	127	85	226	184
Business segments | Gas Distribution and Storage | Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	773	796	2,439	3,083
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
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	13	(1)	26	(41)
Business segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	44	75	101	141
Total revenue	106	150	237	294
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	44	75	101	141
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	0	0
Business segments | Renewable Power Generation | Other revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	59	76	132	154
Eliminations and Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Total revenue	196	275	518	792
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
Revenue not from contract with customers	206	275	537	796
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	(10)	0	(19)	(4)
Total revenue	196	275	518	792
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	11	1
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	2	1	4	4
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	$ 3	$ (1)	$ 4	$ (1)