Other long-term liabilities - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Expected time period for payment of provision for environmental remediation	10 years
Environmental remediation costs charged to income	$ 8	$ 8	$ 8