Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued payroll and related benefits	$ 2,205	$ 1,938
Accrued accounts payable	1,055	1,880
Sales tax and medical device excise tax payable	343	219
Accrued legal and accounting	813	857
Other	693	519
Total accrued liabilities	$ 5,109	$ 5,413