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]
Revenues from contracts with customers	$ 3,577	$ 3,140	$ 7,067	$ 5,384
Leasing revenues	26	34	56	56
Total revenues	3,603	3,174	7,123	5,440
Freight
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,534	3,101	6,961	5,318
Total revenues	3,534	3,101	6,961	5,318
Grain
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	665	537	1,395	1,052
Coal
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	236	219	445	374
Potash
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	180	144	317	276
Fertilizers and sulphur
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	103	89	207	185
Forest products
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	203	187	405	290
Energy, chemicals and plastics
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	695	575	1,397	941
Metals, minerals and consumer products
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	464	440	904	673
Automotive
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	358	257	623	382
Intermodal
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	630	653	1,268	1,145
Non-freight excluding leasing revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 43	$ 39	$ 106	$ 66