Properties - Capital Leases Included in Properties (Details) - CAD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Finance Leased Assets [Line Items]
Cost	$ 194	$ 196
Accumulated depreciation	92	85
Net book value	102	111
Rolling stock
Finance Leased Assets [Line Items]
Cost	186	182
Accumulated depreciation	90	79
Net book value	96	103
Other
Finance Leased Assets [Line Items]
Cost	8	14
Accumulated depreciation	2	6
Net book value	$ 6	$ 8