REVENUE - Recognition and Measurement of Revenues (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
Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	71	37	140	67
Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,856	5,555	12,565	12,738
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,051	3,064	6,137	6,070
Liquids Pipelines | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Liquids Pipelines | Revenue from products and services transferred over time
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 Transmission | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	38	0	78	0
Gas Transmission | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,425	1,403	2,904	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
Gas Distribution and Storage | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	33	37	62	67
Gas Distribution and Storage | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,336	1,013	3,423	3,645
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	44	75	101	141
Renewable Power Generation | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Renewable Power Generation | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 44	$ 75	$ 101	$ 141