Loans and Leases - Summary of Major Loan and Lease Categories (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012		Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	$ 1,499,993	$ 1,481,862	[1]	$ 1,465,449
Unearned lease income	(13,437)	(12,355)
Net deferred costs (fees)	2,205	1,432
Overdraft deposits	161	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	439,907	468,421		497,955
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	580,400	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	84,027	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	32,329	35,179		32,097
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	144,002	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	84,109	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	43,598	43,780		44,037
Lease financings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases held for investment, net of deferred income	$ 91,621	$ 83,857		$ 75,255

[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.