Payment Obligation in Connection with Hirsch Acquisition (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
2018 (remaining three months)	$ 10,535
2019	4,035
2020	450
2021	450
Total	15,920
Less: Current portion - payment obligation	(989)	$ (888)
Long-term payment obligation	2,157	$ 2,998
Hirsch Electronics
Related Party Transaction [Line Items]
2018 (remaining three months)	310
2019	1,277
2020	1,422
2021	367
Present value discount factor	(230)
Total	3,146
Less: Current portion - payment obligation	(989)
Long-term payment obligation	$ 2,157