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Stock-Based Compensation - Summary of Stock-Based Compensation Expenses Related to Performance Stock Units (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock-based compensation expenses $ 4,971 $ 9,175 $ 4,385
Performance Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock-based compensation expenses $ 445 $ 225