Segments and Geographic Information - Schedule of Other Information by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues
Product revenues	$ 7,726	$ 6,325
Service revenues	3,521	3,253
Royalties		899
Total revenues	11,247	10,477
Cost of product revenues	4,313	4,027
Cost of service revenues	2,243	2,323
Total cost of revenues	6,556	6,350
Gross profit	4,691	4,127
Total operating expenses	6,146	5,865
Total non-operating income	14	99
Loss before income taxes	(1,441)	(1,639)
Product [Member]
Revenues
Product revenues	7,726	6,325
Royalties		899
Total revenues	7,726	7,224
Cost of product revenues	4,313	4,027
Total cost of revenues	4,313	4,027
Gross profit	3,413	3,197
Service [Member]
Revenues
Service revenues	3,521	3,253
Total revenues	3,521	3,253
Cost of service revenues	2,243	2,323
Total cost of revenues	2,243	2,323
Gross profit	$ 1,278	$ 930