Segment Information - Summary of Revenue by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 3,535	$ 7,106	$ 7,822	$ 16,016
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	1,449	1,131	2,987	1,641
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	694	998	1,806	2,521
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	642	1,261	1,064	1,986
Taiwan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	425	1,211	808	2,913
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	190	72	423	518
Israel [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	120	291	291	614
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	1	1,813	3	5,163
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 14	$ 329	$ 440	$ 660