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SHAREHOLDERS’ EQUITY AND REGULATORY CAPITAL - Narrative (Detail) - USD ($)
 12 Months Ended
Jan. 24, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Jan. 19, 2016
Sep. 30, 2015
Class of Stock [Line Items]            
Common stock reserved to be issued under dividend reinvestment and stock purchase plan (in shares)   1,045,000        
Shares available to be issued under the plan (in shares)   665,000        
Aggregate amount provided for under shelf registration         $ 100,000,000  
Outstanding shares of common stock authorized to be repurchased (in shares)           416,000
Shares repurchased under the program (in shares)   82,725        
Total cost of shares repurchased under the program   $ 1,438,000        
Shares repurchased under the program, price per share (in dollars per share)   $ 17.38        
Cash dividend declared by the Board (in dollars per share)   $ 0.42 $ 0.35 $ 0.22    
Subsequent Event            
Class of Stock [Line Items]            
Cash dividend declared by the Board (in dollars per share) $ 0.12          
Maximum            
Class of Stock [Line Items]            
Outstanding shares of common stock authorized to be repurchased (as a percent)           5.00%