XML 78 R63.htm IDEA: XBRL DOCUMENT v3.20.4
401(k) Plan - Additional Information (Detail) - 401(k) plan [Member] - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]      
Employer matching contribution of employee contribution, percent 50.00%    
Employer matching contribution, percent 6.00%    
Employer discretionary contribution amount $ 1.1 $ 0.8 $ 0.6