Revenues - Contract Liabilities (Details) - CAD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Contract with Customer, Liability [Abstract]
Opening balance	$ 67	$ 114	$ 67	$ 61
Revenue recognized that was included in the contract liability balance at the beginning of the period	(7)	(19)	(11)	(23)
Increase due to consideration received, net of revenue recognized during the period	9	150	13	207
Closing balance	$ 69	$ 245	$ 69	$ 245