Segment Information and Foreign Operations - Segment and Geographical Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 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	$ 20,495	$ 21,010	$ 39,208	$ 41,074
Long-lived assets by geographic region [Abstract]
Long-lived assets	30,178		30,178		$ 31,422
Reportable Geographical Components | Taiwan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	4,649	3,414	8,784	6,523
Reportable Geographical Components | Europe
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	4,573	5,664	8,951	10,607
Reportable Geographical Components | China
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	4,183	3,561	7,275	6,858
Long-lived assets by geographic region [Abstract]
Long-lived assets	29,259		29,259		30,880
Reportable Geographical Components | Japan
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	2,695	2,753	4,597	5,237
Reportable Geographical Components | North America
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	1,993	2,850	4,449	6,322
Long-lived assets by geographic region [Abstract]
Long-lived assets	919		919		$ 542
Reportable Geographical Components | Asia Pacific (excluding China, Taiwan, and Japan)
Net revenues reported for products shipped to customers in corresponding geographic region [Abstract]
Revenue	$ 2,402	$ 2,768	$ 5,152	$ 5,527