Fair Value of Financial Instruments - Estimated Fair Values and Related Carrying or Notional Amounts (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial Assets:
Securities - available-for-sale	$ 168,447	$ 196,398
Reported Value Measurement [Member]
Financial Assets:
Cash and cash equivalents	38,365	34,467
Interest-bearing time deposits	4,019	4,018
Securities - available-for-sale	168,447	196,398
Other securities	3,679	3,679
Loans held for sale	495	1,221
Loans, net	839,599	816,156
Interest receivable	4,542	4,276
Financial Liabilities:
Total Deposits	928,790	919,340
Fed funds purchased and securities sold under agreement to repurchase	32,181	39,495
Federal Home Loan Bank advances		5,000
Interest payable	418	318
Fair Value [Member]
Financial Assets:
Cash and cash equivalents	38,365	34,467
Interest-bearing time deposits	3,954	4,009
Securities - available-for-sale	168,447	196,398
Other securities	3,679	3,679
Loans held for sale	495	1,221
Loans, net	823,914	819,193
Interest receivable	4,542	4,276
Financial Liabilities:
Total Deposits	928,922	920,109
Fed funds purchased and securities sold under agreement to repurchase	32,181	39,495
Federal Home Loan Bank advances		5,021
Interest payable	418	318
Interest Bearing Deposits [Member] | Reported Value Measurement [Member]
Financial Liabilities:
Total Deposits	525,955	532,660
Interest Bearing Deposits [Member] | Fair Value [Member]
Financial Liabilities:
Total Deposits	525,955	532,660
Non Interest Bearing Deposits [Member] | Reported Value Measurement [Member]
Financial Liabilities:
Total Deposits	215,422	199,114
Non Interest Bearing Deposits [Member] | Fair Value [Member]
Financial Liabilities:
Total Deposits	215,422	199,114
Time Deposits [Member] | Reported Value Measurement [Member]
Financial Liabilities:
Total Deposits	187,413	187,566
Time Deposits [Member] | Fair Value [Member]
Financial Liabilities:
Total Deposits	187,545	188,335
Level 1 [Member]
Financial Assets:
Cash and cash equivalents	38,365	34,467
Securities - available-for-sale	36,935	20,978
Level 2 [Member]
Financial Assets:
Interest-bearing time deposits	3,954	4,009
Securities - available-for-sale	130,085	173,992
Financial Liabilities:
Total Deposits	215,422	199,114
Level 2 [Member] | Non Interest Bearing Deposits [Member]
Financial Liabilities:
Total Deposits	215,422	199,114
Level 3 [Member]
Financial Assets:
Securities - available-for-sale	1,427	1,428
Other securities	3,679	3,679
Loans held for sale	495	1,221
Loans, net	823,914	819,193
Interest receivable	4,542	4,276
Financial Liabilities:
Total Deposits	713,500	720,995
Fed funds purchased and securities sold under agreement to repurchase	32,181	39,495
Federal Home Loan Bank advances		5,021
Interest payable	418	318
Level 3 [Member] | Interest Bearing Deposits [Member]
Financial Liabilities:
Total Deposits	525,955	532,660
Level 3 [Member] | Time Deposits [Member]
Financial Liabilities:
Total Deposits	$ 187,545	$ 188,335