Stock-Based Compensation - Fair Value of Restricted Stock Awards Vested (Detail) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
|
Restricted Stock [Member] | ||||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
Fair value of restricted stock awards vested | $ 3,992 | $ 2,016 | $ 5,232 | $ 3,272 |