Loans - Recorded Investment in Past Due and Non-accruing Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	$ 2,517	$ 1,906
90 Days or More Past Due and Still Accruing		11
Nonaccruals	5,123	6,433
Total Past Due and Nonaccruals	7,640	8,350
Current	341,759	338,872
Total Gross Loans	349,399	347,222
Construction, Land and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	63	93
Nonaccruals	646	672
Total Past Due and Nonaccruals	709	765
Current	38,245	41,364
Total Gross Loans	38,954	42,129
Farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,005	1,030
Total Gross Loans	1,005	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	30,118	28,822
Total Gross Loans	30,118	29,086
Commercial Mortgages (Owner Occupied)
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	393	133
Nonaccruals	1,638	2,350
Total Past Due and Nonaccruals	2,031	2,483
Current	45,194	41,473
Total Gross Loans	47,225	43,956
Residential First Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	1,905	1,304
Nonaccruals	2,461	2,841
Total Past Due and Nonaccruals	4,366	4,145
Current	163,112	160,260
Total Gross Loans	167,478	164,405
Residential Revolving and Junior Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	55	70
Nonaccruals	76	277
Total Past Due and Nonaccruals	131	347
Current	26,461	26,150
Total Gross Loans	26,592	26,497
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due		10
Nonaccruals	278	285
Total Past Due and Nonaccruals	278	295
Current	32,712	34,809
Total Gross Loans	32,990	35,104
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	101	32
90 Days or More Past Due and Still Accruing		11
Nonaccruals	24	8
Total Past Due and Nonaccruals	125	51
Current	4,912	4,964
Total Gross Loans	$ 5,037	$ 5,015