Loans, Allowance for Loan Losses, and Credit Quality Troubled Debt Restructurings Performing and Nonaccrual (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	$ 119,066	$ 121,087
Nonaccrual Restructured Loans	70,354	80,590
Commercial and Industrial Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	30,970	28,140
Nonaccrual Restructured Loans	10,166	12,496
Commercial Real Estate Owner Occupied Portfolio [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	14,336	13,852
Nonaccrual Restructured Loans	11,644	11,514
Commercial Real Estate Investor Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	37,299	41,660
Nonaccrual Restructured Loans	20,540	25,221
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	5,365	4,530
Nonaccrual Restructured Loans	5,168	6,798
Home Equity Port Folio Segments [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	9,933	9,968
Nonaccrual Restructured Loans	6,529	6,698
Installment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	570	653
Nonaccrual Restructured Loans	603	674
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	20,593	22,284
Nonaccrual Restructured Loans	$ 15,704	$ 17,189