Fair Value of Financial Instruments - Estimated Fair Values and Related Carrying or Notional Amounts (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financial Assets:
Securities - available-for-sale	$ 352,974	$ 307,812
Reported Value Measurement [Member]
Financial Assets:
Cash and cash equivalents	175,500	175,706
Interest-bearing time deposits	4,405	4,653
Securities - available-for-sale	352,974	307,812
Other securities	5,939	5,939
Loans held for sale	7,511	7,740
Loans, net	1,327,254	1,289,318
Interest receivable	6,568	6,188
Financial Liabilities:
Total Deposits	1,683,851	1,596,162
Federal funds purchased and securities sold under agreement to repurchase	30,072	30,239
Federal Home Loan Bank advances	17,840	17,861
Interest payable	357	338
Fair Value [Member]
Financial Assets:
Cash and cash equivalents	175,500	175,706
Interest-bearing time deposits	4,451	4,677
Securities - available-for-sale	352,974	307,812
Other securities	5,939	5,939
Loans held for sale	7,511	7,740
Loans, net	1,295,821	1,261,440
Interest receivable	6,568	6,188
Financial Liabilities:
Total Deposits	1,685,393	1,605,890
Federal funds purchased and securities sold under agreement to repurchase	30,072	30,239
Federal Home Loan Bank advances	17,845	17,872
Interest payable	357	338
Interest Bearing Deposits [Member] | Reported Value Measurement [Member]
Financial Liabilities:
Total Deposits	1,056,576	997,462
Interest Bearing Deposits [Member] | Fair Value [Member]
Financial Liabilities:
Total Deposits	1,056,600	1,004,608
Non Interest Bearing Deposits [Member] | Reported Value Measurement [Member]
Financial Liabilities:
Total Deposits	384,558	351,147
Non Interest Bearing Deposits [Member] | Fair Value [Member]
Financial Liabilities:
Total Deposits	384,558	351,147
Time Deposits [Member] | Reported Value Measurement [Member]
Financial Liabilities:
Total Deposits	242,717	247,553
Time Deposits [Member] | Fair Value [Member]
Financial Liabilities:
Total Deposits	244,235	250,135
Level 1 [Member]
Financial Assets:
Cash and cash equivalents	175,500	175,706
Securities - available-for-sale	43,325
Level 2 [Member]
Financial Assets:
Interest-bearing time deposits	4,451	4,677
Securities - available-for-sale	308,110	306,250
Financial Liabilities:
Total Deposits	384,558	351,147
Level 2 [Member] | Non Interest Bearing Deposits [Member]
Financial Liabilities:
Total Deposits	384,558	351,147
Level 3 [Member]
Financial Assets:
Securities - available-for-sale	1,539	1,562
Other securities	5,939	5,939
Loans held for sale	7,511	7,740
Loans, net	1,295,821	1,261,440
Interest receivable	6,568	6,188
Financial Liabilities:
Total Deposits	1,300,835	1,254,743
Federal funds purchased and securities sold under agreement to repurchase	30,072	30,239
Federal Home Loan Bank advances	17,845	17,872
Interest payable	357	338
Level 3 [Member] | Interest Bearing Deposits [Member]
Financial Liabilities:
Total Deposits	1,056,600	1,004,608
Level 3 [Member] | Time Deposits [Member]
Financial Liabilities:
Total Deposits	$ 244,235	$ 250,135