Loans - Recorded Investment in Past Due and Non-accruing Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	$ 1,633	$ 1,502
90 Days or More Past Due and Still Accruing	390	14
Nonaccruals	2,790	1,954
Total Past Due and Nonaccruals	4,813	3,470
Current	298,930	294,584
Total Gross Loans	303,743	298,054
Construction, Land and Land Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	107	64
90 Days or More Past Due and Still Accruing	188
Nonaccruals	666	669
Total Past Due and Nonaccruals	961	733
Current	43,129	42,315
Total Gross Loans	44,090	43,048
Farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,104	1,128
Total Gross Loans	1,104	1,128
Commercial Mortgages (Non-Owner Occupied)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	19,898	20,534
Total Gross Loans	19,898	20,534
Commercial Mortgages (Owner Occupied)
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	34
Nonaccruals	1,497	566
Total Past Due and Nonaccruals	1,531	566
Current	35,541	32,760
Total Gross Loans	37,072	33,326
Residential First Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	1,202	1,270
90 Days or More Past Due and Still Accruing	159
Nonaccruals	262	359
Total Past Due and Nonaccruals	1,623	1,629
Current	138,039	133,638
Total Gross Loans	139,662	135,267
Residential Revolving and Junior Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	73	6
Nonaccruals	31	31
Total Past Due and Nonaccruals	104	37
Current	24,879	25,363
Total Gross Loans	24,983	25,400
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	158	96
Nonaccruals	228	228
Total Past Due and Nonaccruals	386	324
Current	31,373	33,678
Total Gross Loans	31,759	34,002
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-89 Days Past Due	59	66
90 Days or More Past Due and Still Accruing	43	14
Nonaccruals	106	101
Total Past Due and Nonaccruals	208	181
Current	4,967	5,168
Total Gross Loans	$ 5,175	$ 5,349