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Stock-Based Compensation - Summary of Activity of Restricted Stock Units (Detail) - Restricted Stock Units [Member] - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of restricted stock units outstanding, Unvested beginning balance 813,526    
Number of restricted stock units outstanding, Granted 105,633    
Number of restricted stock units outstanding, Vested (309,693)    
Number of restricted stock units outstanding, Cancelled (61,659)    
Number of restricted stock units outstanding, Unvested ending balance 547,807 813,526  
Weighted-average grant date fair value, Unvested beginning balance $ 10.31    
Weighted-average grant date fair value, Granted 6.54 $ 12.48 $ 16.76
Weighted-average grant date fair value, Vested 10.08    
Weighted-average grant date fair value, Cancelled 10.80    
Weighted-average grant date fair value, Unvested ending balance $ 9.49 $ 10.31