Derivative Financial Instruments Cross Currency Swap (Details) $ in Thousands, € in Millions, $ in Millions		3 Months Ended		6 Months Ended
	Dec. 22, 2016 EUR (€)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 22, 2016 AUD ($)	Dec. 01, 2016 EUR (€)	Dec. 01, 2016 AUD ($)
Derivative [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Net of Foreign Currency Transaction Gain (Loss) on Intercompany Loan		$ 272	$ (809)	$ (2,490)	$ (3,667)
Currency Swap [Member]
Derivative [Line Items]
Expiration Date		Jun. 30, 2019
Currency Swap 1 [Member]
Derivative [Line Items]
Notional Amount	€ 85.5					$ 123.9
Currency Swap 2 [Member]
Derivative [Line Items]
Notional Amount	€ 86.3					$ 125.0
BBR Interest rate [Member] | Currency Swap 1 [Member]
Derivative [Line Items]
Derivative, Description of Terms	Australian dollar BBR plus 4.50%
BBR Interest rate [Member] | Currency Swap 2 [Member]
Derivative [Line Items]
Derivative, Description of Terms	Australian dollar BBR plus 4.50%
EURIBOR Interest Rate [Member] | Currency Swap 1 [Member]
Derivative [Line Items]
Derivative, Description of Terms	EURIBOR plus 2.68%
EURIBOR Interest Rate [Member] | Currency Swap 2 [Member]
Derivative [Line Items]
Derivative, Description of Terms	EURIBOR plus 2.90%
Intercompany GRail Loan [Member]
Derivative [Line Items]
Debt Instrument, Face Amount							€ 171.7	$ 248.9
Other income/(loss), net [Member]
Derivative [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments, Net of Foreign Currency Transaction Gain (Loss) on Intercompany Loan		$ 272	$ (809)	$ (2,490)	$ (3,667)