Derivative Financial Instruments Derivative Instruments Not Designated as Hedges Amount Recognized in Earnings (Details) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 EUR (€)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Proceeds from settlement of derivative transactions				$ 45,360	$ 0
Other income/(loss), net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) on cross-currency swap agreements, net	$ 715	$ 272		(1,770)	(2,490)
Currency Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Proceeds from settlement of derivative transactions			€ 17.0	19,272
Intercompany GRail Loan [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) for mark-to-market of the U.K. intercompany loan	(6,400)	3,000		(1,400)	(5,100)
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	$ 7,100	$ (2,800)		$ (300)	$ 2,600