Accounts payable and accrued liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Trade payables	$ 432	$ 401
Accrued charges	286	294
Accrued interest	141	134
Dividends payable	177	127
Stock-based compensation liabilities	126	121
Income and other taxes payable	164	115
Payroll-related accruals	65	68
Operating lease liabilities	59	63
Accrued vacation	60	59
Personal injury and other claims provision	49	37
Deferred revenue	20	27
Deferred real estate lease and license revenue	14	11
Provision for environmental remediation	11	9
Other	5	1
Total accounts payable and accrued liabilities	$ 1,609	$ 1,467