Total Net Revenue Based on Disaggregation Criteria (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Total net revenue	$ 22,237	$ 20,294	$ 41,759	$ 36,822
Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	20,961	19,108	39,217	34,878
Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue	1,276	1,186	2,542	1,944
Americas
Disaggregation Of Revenue [Line Items]
Total net revenue	15,945	15,905	30,670	29,137
Americas | Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	14,760	14,732	28,284	27,220
Americas | Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue	1,185	1,173	2,386	1,917
Europe and the Middle East
Disaggregation Of Revenue [Line Items]
Total net revenue	3,423	2,523	6,353	4,831
Europe and the Middle East | Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	3,332	2,510	6,197	4,804
Europe and the Middle East | Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue	91	13	156	27
Asia-Pacific
Disaggregation Of Revenue [Line Items]
Total net revenue	2,869	1,866	4,736	2,854
Asia-Pacific | Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	$ 2,869	$ 1,866	$ 4,736	$ 2,854