Income Taxes - Reconciliation of the Gross Unrecognized Tax Benefit (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Income Tax Disclosure [Abstract]    
Unrecognized tax benefits at the beginning of the period $ 1,216 $ 865
Additions for current tax positions 421 220
Changes for previous tax positions (207) 131
Unrecognized tax benefits at the end of the period $ 1,430 $ 1,216