Description of business and basis of presentation (Details) - mi mi in Thousands	6 Months Ended
Jun. 30, 2024	Apr. 13, 2023
Description of Business [Line Items]
Miles of transportation network	20
KCS
Description of Business [Line Items]
Ownership percentage, equity method investment		100.00%

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant