Balance Sheet Components - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued research and development costs	$ 4,318	$ 526
Accrued employee related costs	1,529	759
Accrued professional fees	933	140
Other	236	48
Total accrued liabilities	$ 7,016	$ 1,473