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Nature of Operations and Basis of Presentation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 03, 2020
Jan. 08, 2019
Mar. 31, 2020
Mar. 31, 2019
Mar. 16, 2020
Dec. 31, 2019
Number of shares sold   2,145,738,000 4,876,677 4,876,677   4,876,677
Per share of common stock   $ 10.00 $ 0.01     $ 0.01
Gross proceeds from subscription offering   $ 21,500 $ 0 $ 18,274    
Bank's employee stock issued     7,021,000     0
Federal funds rate [Member]            
Increase decrease in interest rate 50.00%          
Charitable Foundation [Member]            
Number Of Shares Contributed   48,767,000        
Maximum [Member] | Federal funds rate [Member]            
Debt instrument interest rate 1.25%       0.25%  
Minimum [Member] | Federal funds rate [Member]            
Debt instrument interest rate 1.00%       0.00%  
Mutual Holding Company [Member]            
Number Of Shares Contributed   2,682,172,000        
Common Stock [Member]            
Bank's employee stock issued   175,528