Other Balance Sheet Accounts - Summary of Accounts Payable and Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Employee compensation	$ 2,220	$ 2,471
Clinical trial accruals	102	1,686
Accounts payable	733	227
Deferred rent	496	432
Other accrued liabilities	361	385
Total accounts payable and accrued expenses	$ 3,912	$ 5,201