Income Taxes (Narrative) (Details) $ in Millions, $ in Billions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2022 MXN ($)	Aug. 31, 2022 USD ($)	Aug. 31, 2022 MXN ($)	Dec. 31, 2021 USD ($)
KCSM [Member]
Income Tax Disclosure [Line Items]
Performance bond posted			$ 291.0	$ 5.6
Refundable Mexican value added tax	$ 78.9				$ 152.2
KCSM [Member] | Short-Term Asset [Member]
Income Tax Disclosure [Line Items]
Refundable Mexican value added tax	$ 78.9				$ 78.0
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Income Tax Disclosure [Line Items]
Percent dividends received deduction	100.00%
State and Local Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryover, amount	$ 64.9
Net operating loss carryover, deferred tax asset, state and local	$ 7.2
State and Local Jurisdiction [Member] | Minimum [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryover, period	10 years
Foreign Tax Authority [Member] | Servicio de Administración Tributaria (SAT) [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryover, amount	$ 27.0
Net operating loss carryover, deferred tax asset, foreign	7.9
Foreign Tax Authority [Member] | Servicio de Administración Tributaria (SAT) [Member] | KCSM [Member] | Tax Year 2014
Income Tax Disclosure [Line Items]
Audit assessment issued by the Mexican tax authority	$ 296.0	$ 5.7