Goodwill and intangible assets (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill
Opening balance	$ 328	$ 329
Additions		0
Foreign exchange impact	16	(1)
Ending balance	344	328
Intangible assets
Cost, Opening balance	64	55
Accumulated amortization, Opening balance	(21)	(18)
Net carrying amount, Opening balance	43	37
Additions		9
Amortization	(3)	(3)
Foreign exchange impact	2	0
Cost, Ending balance	66	64
Accumulated amortization, Ending balance	(24)	(21)
Net carrying amount, Ending balance	42	43
Opening Balance	371	366
Additions		9
Amortization	(3)	(3)
Foreign exchange impact	18	(1)
Ending Balance	$ 386	$ 371