Schedule II – Valuation and Qualifying Accounts (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accruals for personal injury and other claims provision
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance at January 1	$ 132	$ 123	$ 126
Impact of KCS Acquisition	68	0	0
Additions charged to expenses	190	101	114
Payments and other reductions	(202)	(94)	(117)
Impact of FX	(1)	2	0
Ending balance at December 31	187	132	123
Provision for environmental remediation
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance at January 1	83	79	80
Impact of KCS Acquisition	147	0	0
Additions charged to expenses	8	8	10
Payments and other reductions	(15)	(8)	(10)
Impact of FX	(3)	4	(1)
Ending balance at December 31	$ 220	$ 83	$ 79