Information about Geographic Areas and Operating Segments - Revenue and Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Total revenue:
Total revenue	$ 19,653	$ 22,467	$ 61,342	$ 70,644
Long-lived assets:
Total long-lived assets	5,226		5,226		$ 5,351
North America [Member]
Total revenue:
Total revenue	17,982	20,917	57,480	66,275
Long-lived assets:
Total long-lived assets	1,005		1,005		1,025
Asia [Member]
Total revenue:
Total revenue	875	1,018	1,429	1,847
Long-lived assets:
Total long-lived assets	78		78		90
Europe [Member]
Total revenue:
Total revenue	796	$ 532	2,433	$ 2,522
Long-lived assets:
Total long-lived assets	$ 4,143		$ 4,143		$ 4,236