Loans - Recorded Investment in Past Due and Non-accruing Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	$ 1,247	$ 1,906
90 Days or More Past Due and Still Accruing	178	11
Nonaccruals	4,858	6,433
Total Past Due and Nonaccruals	6,283	8,350
Current	361,906	338,872
Total Gross Loans	368,189	347,222
Construction, Land and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	62	93
90 Days or More Past Due and Still Accruing	67
Nonaccruals	627	672
Total Past Due and Nonaccruals	756	765
Current	40,774	41,364
Total Gross Loans	41,530	42,129
Farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,051	1,030
Total Gross Loans	1,051	1,030
Commercial Mortgages (Non-Owner Occupied)
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due		264
Total Past Due and Nonaccruals		264
Current	29,131	28,822
Total Gross Loans	29,131	29,086
Commercial Mortgages (Owner Occupied)
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	294	133
90 Days or More Past Due and Still Accruing	100
Nonaccruals	1,650	2,350
Total Past Due and Nonaccruals	2,044	2,483
Current	43,460	41,473
Total Gross Loans	45,504	43,956
Residential First Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	860	1,304
Nonaccruals	2,276	2,841
Total Past Due and Nonaccruals	3,136	4,145
Current	182,237	160,260
Total Gross Loans	185,373	164,405
Residential Revolving and Junior Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	12	70
Nonaccruals	213	277
Total Past Due and Nonaccruals	225	347
Current	25,164	26,150
Total Gross Loans	25,389	26,497
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	19	10
90 Days or More Past Due and Still Accruing	11
Nonaccruals	92	285
Total Past Due and Nonaccruals	122	295
Current	36,474	34,809
Total Gross Loans	36,596	35,104
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due		32
90 Days or More Past Due and Still Accruing		11
Nonaccruals		8
Total Past Due and Nonaccruals		51
Current	3,615	4,964
Total Gross Loans	$ 3,615	$ 5,015