Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued payroll and related benefits	$ 2,883	$ 1,938
Accrued accounts payable	1,138	1,880
Sales tax and medical device excise tax payable	151	219
Accrued legal, accounting and governance fees	537	857
Other	445	519
Total accrued liabilities	$ 5,154	$ 5,413