Goodwill and intangible assets (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill
Opening balance	$ 329	$ 194
Additions	0	142
Foreign exchange impact	(1)	(7)
Ending balance	328	329
Intangible assets
Cost, Opening balance	55	27
Accumulated amortization, Opening balance	(18)	(15)
Net carrying amount, Opening balance	37	12
Additions	9	31
Amortization	(3)	(3)
Foreign exchange impact	0	(3)
Cost, Ending balance	64	55
Accumulated amortization, Ending balance	(21)	(18)
Net carrying amount, Ending balance	43	37
Opening Balance	366	206
Additions	9	173
Amortization	(3)	(3)
Foreign exchange impact	(1)	(10)
Ending Balance	$ 371	$ 366