Annual report pursuant to Section 13 and 15(d)

Employee Benefits - Additional Information (Detail)

v3.20.4
Employee Benefits - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]      
Accrued expense liability for personal paid time off $ 3.1 $ 2.5  
Bank-Owned Life Insurance      
Defined Contribution Plan Disclosure [Line Items]      
Cash surrender value $ 53.9 52.8  
Section 401(k) Plan      
Defined Contribution Plan Disclosure [Line Items]      
Percent of participant contributions (percent) 75.00%    
Percent of employer contribution (up to, percent) 8.00%    
Contributions $ 2.4 $ 2.4 $ 2.4