Investment in KCS - Narrative (Details) - CAD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Investment in Kansas City Southern	$ 44,955		$ 45,091
Equity earnings of Kansas City Southern	(204)	$ (198)
KCS
Schedule of Equity Method Investments [Line Items]
Investment in Kansas City Southern	44,955		$ 45,091
Equity earnings of Kansas City Southern	(204)	198
Dividends received	300	334
Foreign currency translation	41	608
Amortization of basis difference	$ 42	$ 40

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