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Stock-Based Compensation - Stock Option - Additional Information (Detail)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2020
USD ($)
installment
$ / shares
Dec. 31, 2019
USD ($)
$ / shares
Dec. 31, 2018
USD ($)
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share based compensation option awards contractual term 10 years    
Vesting period for subsequent stock options granted to directors 4 years    
Portion of initial stock options granted to employees that vests on employee's first anniversary 25.00%    
Portion of initial stock options granted to employees that vests ratably over three years after completion of first year of service 75.00%    
Number of vesting equal installments | installment 36    
Options granted, weighted average fair value per share (in dollars per share) | $ / shares $ 5.53 $ 10.19 $ 10.66
Proceeds from exercise of stock options $ 5,634 $ 6,264 $ 6,256
Service option awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
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 $ 6,900    
Unrecognized compensation expenses, weighted average period 1 year 2 months 12 days