Investments (Details) - CAD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Rail investments accounted for on an equity basis	$ 166	$ 160
Other investments	48	43
Total investments	341	203
CMQ
Schedule of Equity Method Investments [Line Items]
Rail investments accounted for on an equity basis	$ 127	$ 0