Revenues - Contract Liabilities (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Contract with Customer, Liability [Abstract]
Opening balance	$ 61	$ 146
Revenue recognized that was included in the contract liability balance at the beginning of the period	(48)	(100)
Increase due to consideration received, net of revenue recognized during the period	54	15
Closing balance	$ 67	$ 61