REVENUE - Major Products and Services (Details) - CAD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									$ 25,939	$ 24,199	$ 23,916
Total revenue	$ 16,217	$ 14,882	$ 11,336	$ 11,038	$ 11,298	$ 9,844	$ 10,432	$ 12,075	$ 53,473	43,649	53,309
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]									Total revenue
Net gain (loss) on derivative									$ 23	(97)	(431)
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									12,213	12,132	11,518
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									6,010	5,780	5,384
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									7,527	6,028	6,733
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									189	259	281
Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									17,521	17,389	16,493
Transportation revenue | Revision of Prior Period, Reclassification, Adjustment
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers										(602)	(584)
Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									1,337	1,073	893
Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers											22
Gas distribution sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									6,734	5,461	6,227
Gas distribution sales | Revision of Prior Period, Reclassification, Adjustment
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers										602	584
Electricity and transmission revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									189	259	281
Commodity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									158	17
Revenue not from contract with customers									26,860	18,964	29,150
Other Revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									674	486	243
Business Segments
Disaggregation of Revenue [Line Items]
Total revenue									52,438	42,189	49,911
Business Segments | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									12,213	12,132	11,518
Total revenue									38,183	29,882	37,174
Business Segments | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									6,010	5,780	5,384
Total revenue									6,199	5,854	5,426
Business Segments | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									7,527	6,028	6,733
Total revenue									7,542	5,976	6,729
Business Segments | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									189	259	281
Total revenue									514	477	582
Business Segments | Transportation revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									11,958	11,875	11,283
Business Segments | Transportation revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									5,279	5,302	5,012
Business Segments | Transportation revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									284	212	198
Business Segments | Transportation revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Storage and other revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									255	257	235
Business Segments | Storage and other revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									573	461	350
Business Segments | Storage and other revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									509	355	308
Business Segments | Storage and other revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Gas gathering and processing revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers											0
Business Segments | Gas gathering and processing revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers											22
Business Segments | Gas gathering and processing revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers											0
Business Segments | Gas gathering and processing revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers											0
Business Segments | Gas distribution sales | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Gas distribution sales | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Gas distribution sales | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									6,734	5,461	6,227
Business Segments | Gas distribution sales | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Electricity and transmission revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Electricity and transmission revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Electricity and transmission revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Business Segments | Electricity and transmission revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									189	259	281
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									25,689	17,494	25,740
Business Segments | Commodity sales | Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									158	17
Revenue not from contract with customers									99	0	0
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	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	0
Business Segments | Other Revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									281	257	(81)
Business Segments | Other Revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									70	72	39
Business Segments | Other Revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									4	(58)	(20)
Business Segments | Other Revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									319	215	305
Eliminations and Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Total revenue									1,035	1,460	3,398
Eliminations and Other | Transportation revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Eliminations and Other | Storage and other revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Eliminations and Other | Gas gathering and processing revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers											0
Eliminations and Other | Gas distribution sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	0	0
Eliminations and Other | Electricity and transmission revenue
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers									0	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									1,072	1,470	3,410
Eliminations and Other | Other Revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									0	0	0
Intersegment revenue
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									(37)	(10)	(12)
Total revenue									(1,904)	916	(1,118)
Intersegment revenue | Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									0	(1)	(3)
Intersegment revenue | Gas Transmission
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									20	2	3
Intersegment revenue | Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									11	6	16
Intersegment revenue | Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue not from contract with customers									$ 6	$ 3	$ (4)