Balance Sheet Components - Summary of Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Compensation and related benefits	$ 2,158	$ 1,276
Professional and consulting services	1,747	961
Other	164	171
Total accrued expenses and other liabilities	$ 4,069	$ 2,408