Description of Business and Summary of Significant Accounting Policies (Revenues by product line and geographic area) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Line Items]
Total	[1]	$ 90,459	$ 87,709
China
Revenue from External Customer [Line Items]
Total	[1]	28,790	36,251
United States
Revenue from External Customer [Line Items]
Total	[1]	15,733	7,989
Germany
Revenue from External Customer [Line Items]
Total	[1]	12,201	11,641
Hungary
Revenue from External Customer [Line Items]
Total	[1]	12,169	13,451
All other countries
Revenue from External Customer [Line Items]
Total	[1],[2]	$ 21,566	$ 18,377

[1] Location is determined by shipment destination.

[2] Revenue from external customers located in countries included in “All other countries” does not individually comprise more than 10% of total revenue for any of the years presented.