Summary of significant accounting policies (Details)	12 Months Ended
Dec. 31, 2023	Apr. 13, 2023
Summary of Significant Accounting Policies [Line items]
Probability threshold for recognizing income tax benefits to be realized upon settlement	50.00%
Short-term investments maturity, maximum	3 months
Market-related asset value, maximum percentage	120.00%
Market-related asset value, minimum percentage	80.00%
Unrecognized actuarial gains and losses, maximum percentage	10.00%
Expected average remaining service period of active employees expected to receive benefits	13 years
Kansas City Southern \| Concession land rights
Summary of Significant Accounting Policies [Line items]
Property, plant and equipment, useful life		50 years
Maximum
Summary of Significant Accounting Policies [Line items]
Amortization period of intangible assets with finite lives (years)	22 years

Cash and Cash Equivalents, Maturity Period, Maximum

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Minimum Market Related Assets Value as Percentage of Market Value

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Probability Thresholds for Recognizing Income Tax Benefits

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 926
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483154/926-20-50-5

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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