Other (Income) Expense (Details) - CAD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Other Income and Expenses [Abstract]
Foreign exchange (gain) loss on debt and lease liabilities	$ (45)	$ 49
Other foreign exchange gains	(3)	(1)
Other	1	3
Total other (income) expense	$ (47)	$ 51