Loans, Allowance for Credit Losses, and Credit Quality Troubled Debt Restructurings Performing and Nonaccrual (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	$ 90,220	$ 98,216
Nonaccrual Restructured Loans	43,699	57,656
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	32,063	33,892
Nonaccrual Restructured Loans	6,496	3,260
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	5,433	10,454
Nonaccrual Restructured Loans	3,900	5,656
Commercial Real Estate Investor [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	22,009	23,127
Nonaccrual Restructured Loans	4,528	15,216
Real Estate Construction [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	714	727
Nonaccrual Restructured Loans	179	2,438
Home Equity Portfolio [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	9,601	10,066
Nonaccrual Restructured Loans	5,551	7,518
Installment and Credit Cards [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	796	974
Nonaccrual Restructured Loans	146	199
Residential Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Performing Restructured Loans	19,604	18,976
Nonaccrual Restructured Loans	$ 22,899	$ 23,369