Segment Information - Summary of Revenue by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 7,086	$ 5,346	$ 14,908	$ 21,362
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	5,409	1,629	8,396	3,270
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	911	1,332	2,717	3,853
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	414	1,267	1,478	3,254
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	114		537	518
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	91	300	503	715
Israel [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	63	104	355	718
Taiwan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	38	305	847	3,218
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	5	320	8	5,484
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 41	$ 89	$ 67	$ 332