Variable interest entities Carrying amounts and maximum exposure to loss for Peru rail joint venture (Details) (Rail joint venture in Peru, Variable interest entity, not primary beneficiary, USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Carrying Amounts, Total	$ 43,052	$ 37,776
Maximum Exposure	63,703	62,483
Investment
Variable Interest Entity [Line Items]
Carrying Amounts, Assets	38,095	32,973
Maximum Exposure	38,095	32,973
Due from unconsolidated company
Variable Interest Entity [Line Items]
Carrying Amounts, Assets	4,957	4,803
Maximum Exposure	4,957	4,803
Guarantees
Variable Interest Entity [Line Items]
Carrying Amounts, Liabilities	0	0
Maximum Exposure	5,920	7,558
Contingent guarantees
Variable Interest Entity [Line Items]
Carrying Amounts, Liabilities	0	0
Maximum Exposure	$ 14,731	$ 17,149