v3.20.4
Defined Contribution Plan - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]      
Contribution of employee compensation (in percent) 100.00%    
Contributions to retirement plan $ 0 $ 0 $ 0
Defined Contribution Plan, Sponsor Location [Extensible List] country:US country:US country:US
Defined Contribution Plan, Tax Status [Extensible List] us-gaap:QualifiedPlanMember us-gaap:QualifiedPlanMember us-gaap:QualifiedPlanMember