Loans, Allowance for Loan Losses, and Credit Quality (Details 8) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	$ 120,719	$ 113,164
Nonaccrual Restructured Loans	79,946	87,493
Commercial and industrial
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	25,622	22,552
Nonaccrual Restructured Loans	14,402	12,211
Commercial real estate - owner occupied
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	6,926	8,138
Nonaccrual Restructured Loans	10,055	9,706
Commercial real estate - investor
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	45,845	43,417
Nonaccrual Restructured Loans	25,996	30,303
Real estate construction
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	11,770	10,977
Nonaccrual Restructured Loans	10,073	14,253
Home Equity
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	9,092	8,950
Nonaccrual Restructured Loans	6,116	6,268
Installment
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	999	1,015
Nonaccrual Restructured Loans	1,054	1,163
Residential Mortgage
Financing Receivable Restructuring [Line Items]
Performing Restructured Loans	20,465	18,115
Nonaccrual Restructured Loans	$ 12,250	$ 13,589