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Stock-Based Compensation - Summary of Grant Date Fair Value of Restricted Stock Unit Awards Vested (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Grant-date fair value $ 3,122 $ 3,141 $ 2,691