Segments and Geographic Information - Summary of Significant Revenues in Following Regions (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 revenues	$ 1,943	$ 2,136	$ 5,475	$ 5,573
North America [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	1,672	1,674	4,616	4,444
Asia [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	181	362	544	844
Europe [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	78	91	285	251
All Other Regions [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	$ 12	$ 9	$ 30	$ 34