Loans and Allowance for Credit Losses Allowance on Sold Loans (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance of loans sold	$ 60,000	$ 23,850		$ 37,010
Charge-offs prior to sale	(15,890)	(8,320)		(11,600)
Net recorded investment in loans sold	(44,110)	15,530	9,900	25,410
Proceeds from sale, net of selling expenses	22,930	8,840		13,480
Total charge-off upon sale	21,180	(6,690)		(11,930)
Existing allocation for credit losses on sold loans	(24,120)	(7,820)		(12,950)
Real-estate commercial mortage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance of loans sold	38,450	9,230		16,920
Charge-offs prior to sale	(8,600)	(2,470)		(4,890)
Net recorded investment in loans sold	(29,850)	6,760		12,030
Proceeds from sale, net of selling expenses	15,910	4,330		7,100
Total charge-off upon sale	13,940	(2,430)		(4,930)
Existing allocation for credit losses on sold loans	(15,090)	(3,430)		(6,300)
Commercial - industrial, financial, and agricultural
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance of loans sold	15,270	6,920		11,650
Charge-offs prior to sale	(3,750)	(1,320)		(2,030)
Net recorded investment in loans sold	(11,520)	5,600		9,620
Proceeds from sale, net of selling expenses	5,170	2,300		4,030
Total charge-off upon sale	6,350	(3,300)		(5,590)
Existing allocation for credit losses on sold loans	(7,510)	(3,370)		(5,330)
Real-estate - construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance of loans sold	6,280	7,700		8,440
Charge-offs prior to sale	(3,540)	(4,530)		(4,680)
Net recorded investment in loans sold	(2,740)	3,170		3,760
Proceeds from sale, net of selling expenses	1,850	2,210		2,350
Total charge-off upon sale	890	(960)		(1,410)
Existing allocation for credit losses on sold loans	$ (1,520)	$ (1,020)		$ (1,320)