Income Taxes - Summary of Movements in Valuation Allowance (Detail) - USD ($) $ in Thousands |
12 Months Ended | |
---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
|
Income Tax Disclosure [Abstract] | ||
Balance at beginning of year | $ 8,601 | $ 5,836 |
Change due to expense and foreign exchange | (113) | 395 |
Deductions | 5,945 | 2,370 |
Balance at end of year | $ 14,433 | $ 8,601 |