Commitments and Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Equipment Loans [Member]
Loss Contingencies [Line Items]
Number of letters of credit issued	4		4
Letters of credit outstanding, amount	$ 1.2		$ 1.2
Percent guarantee of unconsolidated affiliate debt	50.00%		50.00%
Debt Service Reserve or Liquidity Reserve [Member]
Loss Contingencies [Line Items]
Letters of credit outstanding, amount	3.8		3.8
Percent guarantee of unconsolidated affiliate debt	50.00%		50.00%
KCSM [Member]
Loss Contingencies [Line Items]
Total period of time for payments due under railroad concession to Mexican government			50 years
Initial percentage of gross revenue payable under railroad concession to Mexican government			0.50%
Initial period of time for payments due under railroad concession to Mexican government			15 years
Date the percentage of revenue payable to the Mexican government increases under the concession			Jun. 24, 2012
Percentage of gross revenue payable under railroad concession to Mexican government after initial fifteen year period			1.25%
Concession duty expense	$ 1.4	$ 1.3	$ 2.7	$ 2.4
Panama Canal Railway Company [Member] | 7.0% Senior Secured Notes due November 1, 2026 [Member]
Loss Contingencies [Line Items]
Debt instrument, stated interest rate	7.00%		7.00%
Debt instrument, maturity date			Nov. 01, 2026