Business acquisition - Schedule of Allocation of Net Assets and Consideration Paid (Details) - CAD ($) $ in Millions	Apr. 14, 2023	Apr. 13, 2023	Jun. 30, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Goodwill			$ 17,674	$ 344
KCS
Business Acquisition [Line Items]
Cash and cash equivalents		$ 298
Net working capital		51
Properties		28,748
Intangible assets		3,022
Other long-term assets		496
Long-term debt		(4,545)
Deferred income taxes		(6,984)
Other long-term liabilities		(406)
Total identifiable net assets		20,680
Goodwill		17,491
Total identifiable net assets and goodwill		38,171
Fair value of previously held equity method investment	$ 37,227	37,227
Intercompany net balances acquired		12
Fair value of non-controlling interest		932
Total		$ 38,171