Loan Portfolio and Credit Quality Loans by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 5,162,470	$ 5,112,459
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	852,201	866,053
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,858,634	1,813,394
Construction and land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	174,716	153,917
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,035,855	2,032,294
Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	108,963	113,660
Consumer and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 132,101	$ 133,141