Other long-term liabilities (Details) - CAD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Operating lease liabilities, net of current portion	$ 224	$ 248
Stock-based compensation liabilities, net of current portion	125	146
Provision for environmental remediation, net of current portion	68	71
Deferred revenue, net of current portion	47	34
Deferred real estate lease and license revenue, net of current portion	10	18
Deferred gains on sale leaseback transactions	4	5
Other, net of current portion	64	63
Other long-term liabilities	542	585
Aggregate provision for environmental remediation, including current portion	$ 79	$ 80