Other long-term liabilities - Schedule of Other Long-Term Liabilities (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023
Other Liabilities Disclosure [Abstract]
Operating lease liabilities, net of current portion (Note 20)	$ 202	$ 242
Provision for environmental remediation, net of current portion	71	200
Stock-based compensation liabilities, net of current portion	125	161
Deferred revenue, net of current portion (Note 4)	39	16
Deferred lease and license revenue, net of current portion	15	68
Other, net of current portion	68	110
Total other long-term liabilities	520	797
Aggregate provision for environmental remediation, including current portion	$ 83	$ 220
Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	environmental remediation