Loans - Schedule of Loans Not Rated by Class of Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	$ 197,532	$ 204,914
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	1,242	1,924
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	1,149	1,773
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	171,207	176,867
Construction & Land Development [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	7,397	6,539
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	16,537	17,811
Performing [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	196,946	204,312
Performing [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	1,242	1,924
Performing [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	1,149	1,773
Performing [Member] | Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	170,632	176,278
Performing [Member] | Construction & Land Development [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	7,397	6,539
Performing [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	16,526	17,798
Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	586	602
Nonperforming [Member] | Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	575	589
Nonperforming [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Loans not rated by class of loans	$ 11	$ 13