Loan Portfolio and Credit Quality Loans by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 5,106,051	$ 5,112,459
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	882,463	866,053
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,780,901	1,813,394
Construction and land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	150,422	153,917
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,039,072	2,032,294
Home equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	112,504	113,660
Consumer and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 140,689	$ 133,141