Other Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Income and Expenses [Abstract]
Interest income	$ (941)	$ (843)	$ (2,884)	$ (2,309)
Foreign currency (gain) loss, net	1,352	(454)	(1,045)	8,678
Loss on debt retirement	1,149	4,424	1,167	4,835
Other	(245)	130	(3,492)	(54)
Other (income) expense, net	$ 1,315	$ 3,257	$ (6,254)	$ 11,150