Fair Value of Financial Instruments - Estimated Fair Values and Related Carrying or Notional Amounts (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financial Assets:
Cash and Cash Equivalents	$ 32,564	$ 34,467
Interest-bearing time deposits	4,019	4,018
Securities - available-for-sale	187,036	196,398
Loans held for sale	913	1,221
Loans, net	824,226	816,156
Financial Liabilities:
Non-interest bearing Deposits	200,067	199,114
Time Deposits	181,347	187,566
Total deposits	930,766	919,340
Federal Funds Purchased and Securities Sold Under Agreement to Repurchase	23,898	39,495
Federal Home Loan Bank advances	5,000	5,000
Reported Value Measurement [Member]
Financial Assets:
Cash and Cash Equivalents	32,564	34,467
Interest-bearing time deposits	4,019	4,018
Securities - available-for-sale	187,036	196,398
Other Securities	3,717	3,717
Loans held for sale	913	1,221
Loans, net	824,226	816,156
Interest receivable	4,686	4,276
Financial Liabilities:
Interest bearing Deposits	549,352	532,660
Non-interest bearing Deposits	200,067	199,114
Time Deposits	181,347	187,566
Total deposits	930,766	919,340
Federal Funds Purchased and Securities Sold Under Agreement to Repurchase	23,898	39,495
Federal Home Loan Bank advances	5,000	5,000
Interest payable	316	318
Fair Value [Member]
Financial Assets:
Cash and Cash Equivalents	32,564	34,467
Interest-bearing time deposits	4,019	4,009
Securities - available-for-sale	187,036	196,398
Other Securities	3,717	3,717
Loans held for sale	913	1,221
Loans, net	809,064	819,193
Interest receivable	4,686	4,276
Financial Liabilities:
Interest bearing Deposits	550,699	532,660
Non-interest bearing Deposits	200,067	199,114
Time Deposits	179,959	188,335
Total deposits	930,725	920,109
Federal Funds Purchased and Securities Sold Under Agreement to Repurchase	23,898	39,495
Federal Home Loan Bank advances	5,001	5,021
Interest payable	316	318
Level 1 [Member]
Financial Assets:
Cash and Cash Equivalents	32,564	34,467
Securities - available-for-sale	20,791	20,978
Level 2 [Member]
Financial Assets:
Interest-bearing time deposits	4,019	4,009
Securities - available-for-sale	164,835	173,992
Financial Liabilities:
Non-interest bearing Deposits	200,067	199,114
Total deposits	200,067	199,114
Level 3 [Member]
Financial Assets:
Securities - available-for-sale	1,410	1,428
Other Securities	3,717	3,717
Loans held for sale	913	1,221
Loans, net	809,064	819,193
Interest receivable	4,686	4,276
Financial Liabilities:
Interest bearing Deposits	550,699	532,660
Time Deposits	179,959	188,335
Total deposits	730,658	720,995
Federal Funds Purchased and Securities Sold Under Agreement to Repurchase	23,898	39,495
Federal Home Loan Bank advances	5,001	5,021
Interest payable	$ 316	$ 318