Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued payroll and related benefits	$ 3,123	$ 1,938
Accrued accounts payable	1,199	1,880
Sales tax and medical device excise tax payable	96	219
Accrued legal, accounting and governance fees	783	857
Other	417	519
Total accrued liabilities	$ 5,618	$ 5,413