Derivative Financial Instruments Derivative Instruments Not Designated as Hedges Amount Recognized in Earnings (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Cross-currency swap agreements, net	$ (2,485)	$ (2,762)
Other income/(loss), net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cross-currency swap agreements, net	(2,485)	(2,762)
Intercompany GRail Loan [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) for mark-to-market of the U.K. intercompany loan	4,900	(8,200)
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	$ (7,400)	$ 5,400