v3.19.1
Income Taxes - Summary of Changes in Valuation Allowance (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Income Tax Disclosure [Abstract]    
Valuation allowance as of beginning of year $ 5,677 $ 3,795
Increases recorded to accumulated deficit (adoption of ASU 2016-09)   876
Decreases recorded as a benefit to income tax provision   (1,368)
Increases recorded to tax provision 5,580 2,374
Valuation allowance as of end of year $ 11,257 $ 5,677