Derivative Instruments Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	$ 184.8	$ 57.4
Derivative liabilities, fair value	10.4	1.8
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	184.8	57.4
Designated as Hedging Instrument [Member] \| Treasury Lock Agreements [Member] \| Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	184.8	0.0
Designated as Hedging Instrument [Member] \| Treasury Lock Agreements [Member] \| Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	0.0	57.4
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	10.4	1.8
Not Designated as Hedging Instrument [Member] \| Foreign Currency Forward Contracts [Member] \| Accounts Payable and Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	$ 10.4	$ 1.8

KANSAS CITY SOUTHERN 10-Q