Loans, Allowance for Loan Losses and Credit Quality (Summary of Nonaccrual Loans) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Financing Receivable Impaired [Line Items]
Tdrs Recorded Investment On Nonaccrual Status		$ 4,095	$ 6,067
Financing Receivable, Recorded Investment, Nonaccrual Status	[1]	47,098	49,630
Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		30,095	32,055
Commercial Real Estate [Member]
Financing Receivable Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		3,110	3,123
Small Business [Member]
Financing Receivable Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		384	230
Residential Real Estate [Member]
Financing Receivable Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		7,612	8,129
Consumer Home Equity [Member]
Financing Receivable Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		5,861	6,022
Consumer - Other [Member]
Financing Receivable Impaired [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		$ 36	$ 71

[1] (1)Included in these amounts were $4.1 million and $6.1 million of nonaccruing TDRs at June 30, 2018 and December 31, 2017, respectively.