Accounts receivable, net - Schedule of Accounts Receivable (Details) - CAD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 1,057	$ 853
Allowance for credit losses	(41)	(34)
Total accounts receivable, net	1,016	819
Freight
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	785	614
Allowance for credit losses	(27)	(20)
Total accounts receivable, net	758	594
Non-freight
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	272	239
Allowance for credit losses	(14)	(14)
Total accounts receivable, net	$ 258	$ 225