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Short-Term Borrowings - Additional Information (Detail) - USD ($)
9 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Short-term Debt [Line Items]    
Unused lines of credit $ 230,000  
Federal funds purchased 0 $ 23,400,000
Repurchase agreements 129,966  
Unrelated Financial Institution [Member]    
Short-term Debt [Line Items]    
Unused lines of credit $ 20,000  
Renewal period of line of credit 360-day  
Amount of outstanding balance under line of credit $ 0