Other expense (income) (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Income and Expenses [Abstract]
Foreign exchange gain on debt and lease liabilities	$ (7)	$ (14)	$ (94)
Other foreign exchange gains	(4)	(1)	(4)
Acquisition-related costs	247	0	0
Other	1	8	9
Other expense (income)	$ 237	$ (7)	$ (89)