Other Income (Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Component of Other Income (Expense), Nonoperating [Line Items]
Other income (expense)	$ (620)	$ 2,580	$ (2,204)	$ 473
Gain (loss) on currency transactions
Component of Other Income (Expense), Nonoperating [Line Items]
Other income (expense)	(186)	2,662	(1,349)	1,012
Pension and non-pension benefits, excluding service cost
Component of Other Income (Expense), Nonoperating [Line Items]
Other income (expense)	(365)	(243)	(771)	(583)
Other Non-Operating Income (Expense)
Component of Other Income (Expense), Nonoperating [Line Items]
Other income (expense)	$ (69)	$ 161	$ (84)	$ 44