Total Net Revenue Based on Disaggregation Criteria (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Total net revenue	$ 23,026	$ 20,022	$ 64,785	$ 56,844
Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	21,580	18,850	60,796	53,728
Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue	1,446	1,172	3,989	3,116
Americas
Disaggregation Of Revenue [Line Items]
Total net revenue	17,825	15,035	48,495	44,172
Americas | Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	16,471	13,930	44,755	41,150
Americas | Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue	1,354	1,105	3,740	3,022
Europe and the Middle East
Disaggregation Of Revenue [Line Items]
Total net revenue	2,436	2,161	8,790	6,992
Europe and the Middle East | Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	2,344	2,117	8,541	6,921
Europe and the Middle East | Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue	92	44	249	71
Asia-Pacific
Disaggregation Of Revenue [Line Items]
Total net revenue	2,765	2,826	7,500	5,680
Asia-Pacific | Point-in-Time
Disaggregation Of Revenue [Line Items]
Total net revenue	$ 2,765	2,803	$ 7,500	5,657
Asia-Pacific | Over Time
Disaggregation Of Revenue [Line Items]
Total net revenue		$ 23		$ 23