Investment in KCS - Summarized Financial Information, Statement of Income (Details) - CAD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Schedule of Equity Method Investments [Line Items]
Revenues	$ 2,312	$ 1,942	$ 6,352	$ 5,955
Total operating expenses	1,375	1,168	4,012	3,581
Operating income	937	774	2,340	2,374
Income before income tax expense	1,087	641	2,772	2,937
Net income	891	$ 472	2,246	$ 2,320
KCS
Schedule of Equity Method Investments [Line Items]
Revenues	1,152		3,216
Total operating expenses	728		2,024
Operating income	424		1,192
Other	67		164
Income before income tax expense	357		1,028
Net income	$ 263		$ 748