Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	$ 2,319	$ 5,376
60-89 Days Past Due	1,744	2,859
Greater than 90 Days	11,164	17,303
Total Past Due	15,227	25,538
Current	887,072	857,010
Total ending loans balance	902,299	882,548	843,088
Recorded Investment greater than 90 Days and Accruing	201	184
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	525	3,681
60-89 Days Past Due	4	1,004
Greater than 90 Days	7,401	12,398
Total Past Due	7,930	17,083
Current	393,661	396,922
Total ending loans balance	401,591	414,005	381,852
Recorded Investment greater than 90 Days and Accruing	0	0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	0	0
60-89 Days Past Due	18	0
Greater than 90 Days	219	376
Total Past Due	237	376
Current	88,409	68,329
Total ending loans balance	88,646	68,705	76,570
Recorded Investment greater than 90 Days and Accruing	0	0
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	347	394
60-89 Days Past Due	960	1,094
Greater than 90 Days	2,252	2,827
Total Past Due	3,559	4,315
Current	62,948	60,668
Total ending loans balance	66,507	64,983	64,524
Recorded Investment greater than 90 Days and Accruing	158	184
Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	932	630
60-89 Days Past Due	707	494
Greater than 90 Days	1,078	1,510
Total Past Due	2,717	2,634
Current	120,359	120,196
Total ending loans balance	123,076	122,830	126,958
Recorded Investment greater than 90 Days and Accruing	43	0
Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	332	645
60-89 Days Past Due	30	227
Greater than 90 Days	23	69
Total Past Due	385	941
Current	205,938	198,983
Total ending loans balance	206,323	199,924	180,089
Recorded Investment greater than 90 Days and Accruing
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
30-59 Days Past Due	183	26
60-89 Days Past Due	25	40
Greater than 90 Days	191	123
Total Past Due	399	189
Current	15,757	11,912
Total ending loans balance	16,156	12,101	13,095
Recorded Investment greater than 90 Days and Accruing	$ 0	$ 0