Intangible assets - Schedule of Finite-Lived Intangible Assets (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Cost
Beginning balance	$ 3,061	$ 66
Additions (Note 10)		3,022
Foreign exchange impact	254	(27)
Ending balance	3,315	3,061
Accumulated amortization
Beginning balance	(87)	(24)
Amortization	(85)	(61)
Foreign exchange impact	3	(2)
Ending balance	(169)	(87)
Net carrying amount
Beginning balance	2,974	42
Additions (Note 10)		3,022
Amortization	(85)	(61)
Foreign exchange impact	257	(29)
Ending balance	3,146	2,974
Indefinite-lived intangible assets	$ 1,956	$ 1,798