Investment in KCS - Summarized Financial Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 CAD ($)	Mar. 31, 2023 CAD ($)
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 3,520	$ 2,266
Total operating expenses	2,371	1,437
Operating income	1,149	829
Income before income taxes	1,033	963
Net income	$ 775	$ 800
Daily exchange rate used, revenue		1.35
KCS
Schedule of Equity Method Investments [Line Items]
Total revenues		$ 1,187
Total operating expenses		779
Operating income		408
Less : other		74
Income before income taxes		334
Net income		$ 246