Long-term debt (Detail) - CAD ($) $ in Millions		Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
Long-term debt		$ 3,447	$ 3,447
Finance leases		559	564
Total long-term debt	[1]	$ 4,006	$ 4,011
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Total long-term debt	Total long-term debt

[1] (c) Long-term debt included amounts to related parties.3,4473,447