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Stock-Based Compensation - RSU - Additional Information (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
installment
shares
Dec. 31, 2019
shares
Dec. 31, 2018
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of vesting equal installments | installment 36    
Restricted Stock Units (RSU)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of vesting equal installments | installment 4    
Full acceleration of vesting, employee or executive officer subject to involuntary termination, period post change of control of the Company 24 months    
Unrecognized compensation expenses related to unvested RSUs | $ $ 18.3    
Unrecognized compensation expenses, weighted average period 1 year 7 months 6 days    
Grant date fair value of common stock vested (in shares) | shares 581,757 526,175 528,745
Grant date fair value of common stock vested | $ $ 9.6