Balance Sheet Components - Components of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accrued Liabilities And Other Liabilities [Abstract]
Accrued compensation related expenses	$ 3,898	$ 3,894
Accrued accounts payable	2,368	1,915
Customer advances	1,960	1,582
Sales and use tax payable	208	210
Other	815	761
Accrued expenses and other current liabilities	$ 9,249	$ 8,362	[1]

[1] Derived from our audited consolidated financial statements as of December 31, 2016.