Derivative Instruments - (Narrative) (Details) In Millions, unless otherwise specified	1 Months Ended		3 Months Ended					1 Months Ended
	Dec. 31, 2014 Not Designated as Hedging Instrument [Member] Foreign Currency Forward Contracts [Member] USD ($)	Dec. 31, 2014 Not Designated as Hedging Instrument [Member] Foreign Currency Forward Contracts [Member] MXN	Mar. 31, 2015 Not Designated as Hedging Instrument [Member] Foreign Currency Forward Contracts [Member] USD ($)	Mar. 31, 2015 Not Designated as Hedging Instrument [Member] Foreign Currency Forward Contracts [Member] MXN	Mar. 31, 2015 Not Designated as Hedging Instrument [Member] Foreign Currency Zero-Cost Collar Contracts [Member] USD ($)	Mar. 31, 2015 Not Designated as Hedging Instrument [Member] Foreign Currency Zero-Cost Collar Contracts [Member] Put Option [Member] MXN	Mar. 31, 2015 Not Designated as Hedging Instrument [Member] Foreign Currency Zero-Cost Collar Contracts [Member] Call Option [Member] MXN	Jan. 31, 2015 Offsetting Derivative Instrument [Member] Foreign Currency Forward Contracts [Member] USD ($)	Jan. 31, 2015 Offsetting Derivative Instrument [Member] Foreign Currency Forward Contracts [Member] MXN
Derivative [Line Items]
Aggregate notional amount of foreign currency contracts	$ 300.0	4,364.7	$ 300.0	4,480.4	$ 80.0			$ 298.8	4,364.7
Weighted-average exchange rate of foreign currency forward contracts (in Ps. per USD)		14.55		14.93					14.61
Maturity date of foreign currency contracts	Jan. 15, 2015	Jan. 15, 2015	Jan. 15, 2016	Jan. 15, 2016	Jan. 15, 2016			Jan. 15, 2015	Jan. 15, 2015
Weighted-average exchange rate of foreign currency zero-cost collar contracts (in Ps. per USD)						15.11	15.90

Kansas City Southern de Mexico, S.A. de C.V. 10-Q