Schedule II – Valuation and Qualifying Accounts (Details) - Provisions for contingent liabilities(1)(2) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as at January 1	$ 314	$ 130	$ 114
Impact of KCS Acquisition	44	215	0
Additions charged to expenses	171	191	102
Payments and other reductions	(194)	(218)	(92)
Impact of FX	25	(4)	6
Balance as at December 31	$ 360	$ 314	$ 130