Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.20.4
Summary of Significant Accounting Policies - Additional Information (Detail)
12 Months Ended
Mar. 26, 2020
Dec. 31, 2020
USD ($)
Segment
$ / shares
shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Jan. 01, 2021
USD ($)
Subsidiary Sale Of Stock [Line Items]          
Insurance Coverage   $ 250,000      
Regulatory reserve requirement percentage 0.00%        
Marketable equity securities with fair value   $ 24,000,000      
Number of reporting units | Segment   1      
Impairment charges   $ 0 $ 0 $ 0  
Interest and penalties   $ 0 0 $ 23,000  
Repurchase of common stock shares | shares   1,233,739      
Repurchase of common stock average price per share | $ / shares   $ 12.93      
Number of reportable operating segment | Segment   1      
Minimum          
Subsidiary Sale Of Stock [Line Items]          
Loan guarantee, percentage   75.00%      
Minimum | Subsequent Event | Accounting Standards Update 2016-02          
Subsidiary Sale Of Stock [Line Items]          
Right of use asset         $ 6,000,000.0
Lease liability         6,000,000.0
Minimum | Bank premises          
Subsidiary Sale Of Stock [Line Items]          
Property, Plant and Equipment Useful Life   30 years      
Minimum | Computer Equipment          
Subsidiary Sale Of Stock [Line Items]          
Property, Plant and Equipment Useful Life   3 years      
Minimum | Furniture And Equipment          
Subsidiary Sale Of Stock [Line Items]          
Property, Plant and Equipment Useful Life   5 years      
Maximum          
Subsidiary Sale Of Stock [Line Items]          
Loan guarantee, percentage   85.00%      
Maximum | Subsequent Event | Accounting Standards Update 2016-02          
Subsidiary Sale Of Stock [Line Items]          
Right of use asset         6,400,000
Lease liability         $ 6,400,000
Maximum | Core Deposit          
Subsidiary Sale Of Stock [Line Items]          
Estimated useful life   12 years      
Maximum | Bank premises          
Subsidiary Sale Of Stock [Line Items]          
Property, Plant and Equipment Useful Life   40 years      
Maximum | Computer Equipment          
Subsidiary Sale Of Stock [Line Items]          
Property, Plant and Equipment Useful Life   5 years      
Maximum | Furniture And Equipment          
Subsidiary Sale Of Stock [Line Items]          
Property, Plant and Equipment Useful Life   10 years      
Federal Reserve Bank          
Subsidiary Sale Of Stock [Line Items]          
Cash on hand   $ 0 $ 61,600,000