Inventories - Reserve (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance at beginning of year	$ (9,470)	$ (5,697)	$ (7,112)
Charged to costs and expenses	(8,147)	(7,468)	(4,197)
Deduction for reserved inventory disposed or sold	3,542	3,153	4,860
Foreign currency translation	603	542	752
Balance at end of year	(13,472)	(9,470)	(5,697)
Inventory Reserve
Balance at beginning of year	$ (1,000)	(2,600)	(1,900)
Charged to costs and expenses		(2,200)	(2,500)
Deduction for reserved inventory disposed or sold		400	2,300
Foreign currency translation		200	500
Balance at end of year		$ (1,000)	$ (2,600)