Income Taxes - Reconciliation of Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Income Tax Disclosure [Abstract] | |||
| Beginning Balance | $ 4,061 | $ 332 | $ 287 |
| Decreases based on tax positions taken during a prior period | (3,559) | (102) | |
| Increases based on tax positions taken during a prior period | 4,628 | 3,562 | |
| Increases based on tax positions taken during a current period | 4,986 | 167 | 147 |
| Ending Balance | $ 10,116 | $ 4,061 | $ 332 |