Segment Information and Foreign Operations - Segment and Geographical Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) segment	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | segment	1
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	$ 20,616	$ 18,713
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	27,141		$ 27,805
Reportable Geographical Components | Europe
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	5,598	4,378
Reportable Geographical Components | China
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	4,422	3,092
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	26,923		27,487
Reportable Geographical Components | Taiwan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	3,318	4,135
Reportable Geographical Components | Japan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	3,140	1,902
Reportable Geographical Components | Asia Pacific (excluding China, Taiwan, and Japan)
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	2,071	2,750
Reportable Geographical Components | North America
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	2,067	$ 2,456
Long-lived assets by geographic region, net of depreciation:
Long-lived assets	$ 218		$ 318