Investment in KCS - Summarized Financial Information, Statement of Income (Details) - CAD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Total revenues		$ 8,814	$ 7,995	$ 7,710
Total operating expenses		5,485	4,789	4,399
Operating income		3,329	3,206	3,311
Other		17	237	(7)
Income before income tax expense		4,145	3,620	3,202
Net income (loss)		3,517	$ 2,852	$ 2,444
Kansas City Southern
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 178	4,387
Total operating expenses	287	2,790
Operating income	(109)	1,597
Other	12	(108)
Income before income tax expense	(121)	1,705
Net income (loss)	$ (106)	$ 1,278