REVENUE - Recognition and Measurement of Revenues (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 6,778	$ 7,213
Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	69	30
Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6,709	7,183
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,086	3,006
Liquids Pipelines | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Liquids Pipelines | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,086	3,006
Gas Transmission
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,519	1,479
Gas Transmission | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40	0
Gas Transmission | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,479	1,479
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,116	2,662
Gas Distribution and Storage | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	29	30
Gas Distribution and Storage | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,087	2,632
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	66
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
Renewable Power Generation | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 57	$ 66