Other (income) expense (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other expense [Line Items]
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other (income) expense (Note 5, 10, 16, 17)	Other (income) expense (Note 5, 10, 16, 17)
Other (income) expense (Note 5, 10, 16, 17)	$ (42)	$ 52	$ 17
Forward starting swaps
Other expense [Line Items]
Foreign exchange loss on FX forward contracts (Note 17)	4	39	0
Other Expense
Other expense [Line Items]
Other foreign exchange gains	(6)	(12)	0
Acquisition-related costs (Note 10)	0	6	0
Gain on debt repurchases (Note 16)	(22)	0	0
Other	$ (18)	$ 19	$ 17