Properties - Net Properties (Details) - CAD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Cost	$ 31,680	$ 29,851
Accumulated depreciation	9,295	8,651
Net book value	$ 22,385	21,200
Track and roadway
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	2.80%
Cost	$ 22,488	21,210
Accumulated depreciation	6,308	5,893
Net book value	$ 16,180	15,317
Buildings
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	2.70%
Cost	$ 1,069	1,022
Accumulated depreciation	254	266
Net book value	$ 815	756
Rolling stock
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	2.80%
Cost	$ 5,085	4,793
Accumulated depreciation	1,523	1,419
Net book value	$ 3,562	3,374
Other
Property, Plant and Equipment [Line Items]
Weighted average annual depreciation rate	5.80%
Cost	$ 3,038	2,826
Accumulated depreciation	1,210	1,073
Net book value	$ 1,828	$ 1,753