Segment Reporting - Schedule of Revenue by Geographic Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Total	$ 48,733	$ 46,405	$ 98,575	$ 92,451
% of Total	100.00%	100.00%	100.00%	100.00%
United States [Member]
Segment Reporting Information [Line Items]
Total	$ 27,250	$ 26,520	$ 53,761	$ 51,363
% of Total	55.90%	57.20%	54.50%	55.50%
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total	$ 2,247	$ 1,530	$ 6,572	$ 3,378
% of Total	4.60%	3.30%	6.70%	3.70%
Germany [Member]
Segment Reporting Information [Line Items]
Total	$ 6,535	$ 5,389	$ 12,567	$ 11,233
% of Total	13.40%	11.60%	12.80%	12.20%
Japan [Member]
Segment Reporting Information [Line Items]
Total	$ 12,532	$ 12,773	$ 25,348	$ 25,980
% of Total	25.70%	27.50%	25.70%	28.10%
Other Asia [Member]
Segment Reporting Information [Line Items]
Total	$ 169	$ 193	$ 327	$ 497
% of Total	0.40%	0.40%	0.30%	0.50%