Loans and Leases - Non-Performing Loans and Leases (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	$ 17,337,000	$ 23,235,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	5,469,000	7,943,000
Loans and Leases 90 Days or more Past Due and Accruing Interest	451,000	413,000
Total Non- Performing Loans and Leases	23,257,000	31,591,000
Nonaccrual Troubled Debt Restructured Loans And Lease Modifications	3,100,000	1,600,000
Commercial, Financial and Agricultural [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	5,002,000	4,253,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	2,851,000	1,329,000
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	12,000
Total Non- Performing Loans and Leases	7,853,000	5,594,000
Real Estate-Commercial [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	4,413,000	8,091,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	2,618,000	4,271,000
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	7,031,000	12,362,000
Real Estate-Construction [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	5,931,000	9,159,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	2,307,000
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	5,931,000	11,466,000
Real Estate-Residential Secured for Business Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	915,000	224,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	915,000	224,000
Real Estate-Residential Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	512,000	1,101,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	512,000	1,101,000
Real Estate-Home Equity Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	184,000	77,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	31,000	23,000
Total Non- Performing Loans and Leases	215,000	100,000
Loans to Individuals [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	0	0
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	36,000
Loans and Leases 90 Days or more Past Due and Accruing Interest	365,000	319,000
Total Non- Performing Loans and Leases	365,000	355,000
Lease Financings [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	380,000	330,000
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	55,000	59,000
Total Non- Performing Loans and Leases	$ 435,000	$ 389,000