Revenues Based on Customer Location (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total revenues	$ 16,508	$ 13,834
United States
Segment Reporting Information [Line Items]
Total revenues	1,760	1,961
Europe and Middle East
Segment Reporting Information [Line Items]
Total revenues	2,474	1,445
Asia Pacific
Segment Reporting Information [Line Items]
Total revenues	12,274	10,428
China
Segment Reporting Information [Line Items]
Total revenues	8,892	7,478
S. Korea
Segment Reporting Information [Line Items]
Total revenues	$ 2,703	$ 0	[1]

[1] *) Less than 10%