Loans and Allowance for Credit Losses Loans Modified Under Troubled Debt Restructurings (Details) (USD $) In Thousands	Sep. 30, 2011		Dec. 31, 2010
Financing Receivable, Modifications [Line Items]
Total accruing troubled debt restructurings	$ 67,826		$ 67,809
Non-accrual troubled debt restructurings	49,432	[1]	51,175	[1]
Total troubled debt restructurings	117,258		118,984
Real-estate - residential mortgage
Financing Receivable, Modifications [Line Items]
Total accruing troubled debt restructurings	36,113		37,826
Real-estate commercial mortage
Financing Receivable, Modifications [Line Items]
Total accruing troubled debt restructurings	23,419		18,778
Real-estate - construction
Financing Receivable, Modifications [Line Items]
Total accruing troubled debt restructurings	5,871		5,440
Commercial - industrial, financial, and agricultural
Financing Receivable, Modifications [Line Items]
Total accruing troubled debt restructurings	2,229		5,502
Consumer and Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Total accruing troubled debt restructurings	$ 194		$ 263

[1] Included within non-accrual loans in table detailing non-performing assets above.