Derivative Financial Instruments (Details)	3 Months Ended		9 Months Ended							3 Months Ended	9 Months Ended
	Sep. 30, 2011 USD ($)	Sep. 30, 2010 USD ($)	Sep. 30, 2011 USD ($)	Sep. 30, 2010 USD ($)	Dec. 01, 2010 USD ($)	Dec. 01, 2010 AUD	Oct. 02, 2008 USD ($)	Dec. 01, 2010 FreightLink [Member] USD ($)	Dec. 01, 2010 FreightLink [Member] AUD	Sep. 30, 2011 Cross-currency swap [Member] USD ($)	Sep. 30, 2011 Cross-currency swap [Member] USD ($)	Sep. 30, 2011 AUD BBSW Interest Rate [Member] Cross-currency swap [Member]	Sep. 30, 2011 Libor Interest Rate [Member] Cross-currency swap [Member]	Sep. 30, 2011 Cross-currency swap [Member] USD ($)
Derivatives [Line Items]
Notional amount of interest rate derivatives							$ 120,000,000
Derivative, fixed interest rate							3.88%
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net			0
Third-party debt associated with foreign currency debt	146,300,000		146,300,000
Acquisition of assets								320,023,000	331,936,000
Notional amount of foreign currency derivatives					100,600,000	105,000,000
Derivative, description of variable rate basis												Australian dollar BBSW plus 3.125%	LIBOR plus 2.48%
Interest (expense)/income										(1,566,000)	(4,526,000)
Other (expense)/income	(1,064,000)	418,000	(595,000)	693,000						103,000	222,000
Derivative liability, net														$ 1,500,000