Balance Sheet Information - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Payroll, bonuses, and other employee benefits	$ 2,298	$ 2,029
Inventory receipts	1,531	1,622
Paid time off	1,084	1,230
Warranties	418	394
Income and sales taxes	344	546
Professional fees and contractors	224	320
Deferred revenues	199	104
Employee stock purchase plan	128	300
Real estate taxes	122	152
Customer prepayments	45	164
Restructuring	24	126
Other	317	190
Total	$ 6,734	$ 7,177