REVENUE - Schedule of Major Products and Services (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 8,809	$ 6,778
Total revenue	18,502	11,038
Net gain (loss) on derivative	99	(22)
Revenues from lease contracts	158	140
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,173	3,086
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,677	1,519
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,917	2,116
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	42	57
Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,675	4,458
Transportation revenue | Revision of Prior Period, Reclassification, Adjustment
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		(258)
Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	398	299
Gas distribution revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,670	1,924
Total revenue	3,699	1,960
Electricity revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	42	57
Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	24	40
Revenue not from contract with customers	9,525	4,105
Other Revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	168	155
Gas Distribution Service | Revision of Prior Period, Reclassification, Adjustment
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		258
Business Segments
Disaggregation of Revenue [Line Items]
Total revenue	17,975	10,716
Business Segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,173	3,086
Total revenue	12,184	6,882
Business Segments | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,677	1,519
Total revenue	1,715	1,572
Business Segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,917	2,116
Total revenue	3,956	2,131
Business Segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	42	57
Total revenue	120	131
Business Segments | Transportation revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,105	3,024
Business Segments | Transportation revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,480	1,341
Business Segments | Transportation revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	90	93
Business Segments | Transportation revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Storage and other revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	68	62
Business Segments | Storage and other revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	173	138
Business Segments | Storage and other revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	157	99
Business Segments | Storage and other revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Gas distribution revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Gas distribution revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Gas distribution revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,670	1,924
Business Segments | Gas distribution revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Electricity revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Electricity revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Electricity revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Business Segments | Electricity revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	42	57
Business Segments | Commodity sales | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Revenue not from contract with customers	8,934	3,733
Business Segments | Commodity sales | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	24	40
Revenue not from contract with customers	37	41
Business Segments | Commodity sales | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Revenue not from contract with customers	0	0
Business Segments | Commodity sales | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Revenue not from contract with customers	0	0
Business Segments | Other Revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	77	63
Business Segments | Other Revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	(7)	6
Business Segments | Other Revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	21	13
Business Segments | Other Revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	77	73
Eliminations and Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Total revenue	527	322
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	0
Revenue not from contract with customers	554	331
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	(27)	(9)
Total revenue	40	(642)
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	8	6
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	18	2
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers	$ 1	$ 1