Loans and Leases - Summary of Major Loan and Lease Categories (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012		Sep. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	$ 1,526,241	$ 1,481,862	[1]	$ 1,469,511
Unearned lease income	(14,192)	(12,355)
Net deferred costs (fees)	2,523	1,432
Overdraft deposits	156	128
Commercial, financial and agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	430,818	468,421		476,125
Real estate-commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	606,030	530,122
Real estate-construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	74,847	91,250
Real estate-residential secured for business purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	35,673	35,179		32,820
Real estate-residential secured for personal purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	143,374	146,526
Real estate-home equity secured for personal purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	90,527	82,727
Loans to individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	42,211	43,780		42,626
Lease financings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	$ 102,761	$ 83,857		$ 76,562

[1] Note: The consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U. S. generally accepted accounting principles for complete financial statements. See accompanying notes to the unaudited consolidated financial statements.