Loans and Leases - Non-Performing Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	$ 14,183	$ 17,337
Accruing Troubled Debt Restructured Loans and Lease Modifications	5,245	5,469
Loans and Leases 90 Days or more Past Due and Accruing Interest	379	451
Total Non- Performing Loans and Leases	19,807	23,257
Nonaccrual Troubled Debt Restructured Loans And Lease Modifications	93	3,100
Commercial, Financial and Agricultural [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	6,915	5,002
Accruing Troubled Debt Restructured Loans and Lease Modifications	1,602	2,851
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	8,517	7,853
Real Estate-Commercial [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	4,314	4,413
Accruing Troubled Debt Restructured Loans and Lease Modifications	2,449	2,618
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	6,763	7,031
Real Estate-Construction [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	0	5,931
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	0	5,931
Real Estate-Residential Secured for Business Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	1,863	915
Accruing Troubled Debt Restructured Loans and Lease Modifications	763	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	2,626	915
Real Estate-Residential Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	376	512
Accruing Troubled Debt Restructured Loans and Lease Modifications	421	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non- Performing Loans and Leases	797	512
Real Estate-Home Equity Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	275	184
Accruing Troubled Debt Restructured Loans and Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	31
Total Non- Performing Loans and Leases	275	215
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	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	173	365
Total Non- Performing Loans and Leases	173	365
Lease Financings [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	440	380
Accruing Troubled Debt Restructured Loans and Lease Modifications	10	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	206	55
Total Non- Performing Loans and Leases	$ 656	$ 435