Loans and Leases - Non-Performing Loans and Leases (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	$ 18,814	$ 23,235
Accruing Troubled Debt Restructured Loans And Lease Modifications	5,463	7,943
Loans and Leases 90 Days or more Past Due and Accruing Interest	344	413
Total Non-Performing Loans and Leases	24,621	31,591
Nonaccrual Troubled Debt Restructured Loans And Lease Modifications	3,392	1,583
Commercial, Financial and Agricultural [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	5,050	4,253
Accruing Troubled Debt Restructured Loans And Lease Modifications	2,657	1,329
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	12
Total Non-Performing Loans and Leases	7,707	5,594
Real Estate-Commercial [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	4,482	8,091
Accruing Troubled Debt Restructured Loans And Lease Modifications	2,806	4,271
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non-Performing Loans and Leases	7,288	12,362
Real Estate-Construction [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	7,570	9,159
Accruing Troubled Debt Restructured Loans And Lease Modifications	0	2,307
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	0
Total Non-Performing Loans and Leases	7,570	11,466
Real Estate-Residential Secured for Business Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	822	224
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	822	224
Real Estate-Residential Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	526	1,101
Accruing Troubled Debt Restructured Loans And Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	41	0
Total Non-Performing Loans and Leases	567	1,101
Real Estate-Home Equity Secured for Personal Purpose [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	77	77
Accruing Troubled Debt Restructured Loans And Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	0	23
Total Non-Performing Loans and Leases	77	100
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
Loans and Leases 90 Days or more Past Due and Accruing Interest	257	319
Total Non-Performing Loans and Leases	257	355
Lease Financings [Member]
Non-Performing Loans and Leases [Line Items]
Nonaccrual Loans and Leases	287	330
Accruing Troubled Debt Restructured Loans And Lease Modifications	0	0
Loans and Leases 90 Days or more Past Due and Accruing Interest	46	59
Total Non-Performing Loans and Leases	$ 333	$ 389