Loans and Allowance for Credit Losses Allocation for Credit Losses on Loans Sold (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of loans sold	$ 13,160
Charge-offs prior to sale	(3,280)
Net recorded investment in loans sold	9,880
Proceeds from sale, net of selling expenses	4,640
Total charge-off upon sale	5,240
Existing allocation for credit losses on sold loans	(5,130)
Commercial - industrial, financial, and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of loans sold	4,730
Charge-offs prior to sale	(710)
Net recorded investment in loans sold	4,020
Proceeds from sale, net of selling expenses	1,730
Total charge-off upon sale	2,290
Existing allocation for credit losses on sold loans	(1,960)
Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of loans sold	740
Charge-offs prior to sale	(150)
Net recorded investment in loans sold	590
Proceeds from sale, net of selling expenses	140
Total charge-off upon sale	450
Existing allocation for credit losses on sold loans	(300)
Real-estate commercial mortage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of loans sold	7,690
Charge-offs prior to sale	(2,420)
Net recorded investment in loans sold	5,270
Proceeds from sale, net of selling expenses	2,770
Total charge-off upon sale	2,500
Existing allocation for credit losses on sold loans	$ (2,870)