Derivative Financial Instruments Derivative Instruments Not Designated as Hedges Amount Recognized in Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Cross-currency swap agreements, net	$ (2,410)	$ (2,729)	$ (4,900)	$ (6,397)
Other income/(loss), net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cross-currency swap agreements, net	(2,410)	(842)	(4,900)	(4,510)
Currency Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) on mark-to-market of the swaps		1,700		2,000
Currency Swap [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	(1,887)	0	(1,887)
Intercompany GRail Loan [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) for mark-to-market of the U.K. intercompany loan	(3,000)	$ (2,500)	(8,100)	$ (6,500)
Mark to Market [Member] | Currency Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) on mark-to-market of the swaps	$ 600		$ 3,200