REVENUES - Recognition and Measurement of Revenues (Details) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 5,171	$ 5,348	$ 17,976	$ 17,009
Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38	41	105	77
Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,133	5,307	17,871	16,932
Liquids Pipelines
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,921	3,020	8,991	8,385
Liquids Pipelines | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Liquids Pipelines | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,921	3,020	8,991	8,385
Gas Transmission and Midstream
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,412	1,355	4,294	3,937
Gas Transmission and Midstream | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Gas Transmission and Midstream | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,412	1,355	4,294	3,937
Gas Distribution and Storage
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	759	905	4,471	4,476
Gas Distribution and Storage | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38	41	105	77
Gas Distribution and Storage | Revenue from products and services transferred over time
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	721	864	4,366	4,399
Renewable Power Generation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	79	68	220	211
Renewable Power Generation | Revenues from products transferred at a point in time
Disaggregation of Revenue [Line Items]
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]
Revenue from contracts with customers	$ 79	$ 68	$ 220	$ 211