Derivative Financial Instruments Foreign Currency Exchange Rate Risk (Details)		3 Months Ended							6 Months Ended				3 Months Ended		6 Months Ended
	Jun. 30, 2013 USD ($)	Dec. 31, 2010 FreightLink [Member] USD ($)	Dec. 31, 2010 FreightLink [Member] AUD	Dec. 31, 2012 Cross-Currency Swap 1 [Member] USD ($)	Dec. 01, 2010 Cross-Currency Swap 1 [Member] USD ($)	Dec. 01, 2010 Cross-Currency Swap 1 [Member] AUD	Dec. 03, 2012 Cross-currency swap [Member] USD ($)	Dec. 03, 2012 Cross-currency swap [Member] AUD	Jun. 30, 2013 AUD BBSW Interest Rate [Member] Cross-Currency Swap 1 [Member]	Jun. 30, 2013 AUD BBSW Interest Rate [Member] Cross-currency swap [Member]	Jun. 30, 2013 LIBOR Interest Rate [Member] Cross-Currency Swap 1 [Member]	Jun. 30, 2013 LIBOR Interest Rate [Member] Cross-currency swap [Member]	Jun. 30, 2013 Not Designated as Hedging Instrument [Member] Cross-currency swap [Member] USD ($)	Jun. 30, 2012 Not Designated as Hedging Instrument [Member] Cross-currency swap [Member] USD ($)	Jun. 30, 2013 Not Designated as Hedging Instrument [Member] Cross-currency swap [Member] USD ($)	Jun. 30, 2012 Not Designated as Hedging Instrument [Member] Cross-currency swap [Member] USD ($)
Derivatives [Line Items]
Liability, Reporting Currency Denominated, Value	$ 163,800,000
Total consideration		320,000,000	331,900,000
Derivative, notional amount					100,600,000	105,000,000	109,600,000	105,000,000
Derivative settlement payment				9,100,000
Derivative, description of variable rate basis									Australian dollar BBSW plus 3.125%	Australian dollar BBSW plus 3.25%	LIBOR plus 2.48%	LIBOR plus 2.82%
Interest expense, net													$ (717,000)	$ (1,203,000)	$ (1,532,000)	$ (2,521,000)