REVENUE - Schedule of Major Products and Services (Details) - CAD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 6,523	$ 5,927	$ 15,332	$ 12,705
Total revenue	14,876	11,336	33,378	22,374
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,970	3,051	6,143	6,137
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,539	1,463	3,216	2,982
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,962	1,369	5,879	3,485
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	52	44	94	101
Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,309	4,318	8,984	8,776
Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	389	327	787	626
Gas distribution sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,745	1,200	5,415	3,124
Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue	1,763	1,208	5,462	3,169
Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	52	44	94	101
Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	28	38	52	78
Revenue not from contract with customers	8,096	5,253	17,621	9,358
Other Revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	257	156	425	311
Gas Distribution Service | Revision of Prior Period, Reclassification, Adjustment
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		427		685
Business Segments
Disaggregation of Revenue [Line Items]
Total revenue	14,602	11,140	32,577	21,856
Business Segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,970	3,051	6,143	6,137
Total revenue	10,837	8,158	23,021	15,040
Business Segments | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,539	1,463	3,216	2,982
Total revenue	1,604	1,492	3,319	3,064
Business Segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,962	1,369	5,879	3,485
Total revenue	2,016	1,384	5,972	3,515
Business Segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	52	44	94	101
Total revenue	145	106	265	237
Business Segments | Transportation revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,895	2,986	6,000	6,010
Business Segments | Transportation revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,349	1,290	2,829	2,631
Business Segments | Transportation revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	65	42	155	135
Business Segments | Transportation revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Storage and other revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	75	65	143	127
Business Segments | Storage and other revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	162	135	335	273
Business Segments | Storage and other revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	152	127	309	226
Business Segments | Storage and other revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Gas distribution sales | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Gas distribution sales | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Gas distribution sales | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,745	1,200	5,415	3,124
Business Segments | Gas distribution sales | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Electricity revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Electricity revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Electricity revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Business Segments | Electricity revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	52	44	94	101
Business Segments | Commodity sales | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Revenue not from contract with customers	7,787	5,036	16,721	8,769
Business Segments | Commodity sales | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	28	38	52	78
Revenue not from contract with customers	29	11	66	52
Business Segments | Commodity sales | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Revenue not from contract with customers	0	0	0	0
Business Segments | Commodity sales | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Revenue not from contract with customers	0	0	0	0
Business Segments | Other Revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	80	71	157	134
Business Segments | Other Revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	32	13	25	19
Business Segments | Other Revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	55	13	76	26
Business Segments | Other Revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	90	59	167	132
Eliminations and Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Total revenue	274	196	801	518
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 sales
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	0	0
Revenue not from contract with customers	280	206	834	537
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	(6)	(10)	(33)	(19)
Total revenue	1,167	(155)	1,207	(797)
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	4	5	12	11
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	(1)	2	17	4
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	$ 3	$ 3	$ 4	$ 4