Loans, Allowance for Loan Losses and Credit Quality (Weighted Average FICO Scores and the Weighted Average Combined LTV Ratio) (Details) - score	Sep. 30, 2017	Dec. 31, 2016
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable With Quality Of Loan Based On Weighted Average Fico Rating	745	743
Financing Receivable With Credit Quality Of Loan Based Upon the Weighted Average Loan-To-Value Ratio	61.00%	63.20%
Consumer Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable With Quality Of Loan Based On Weighted Average Fico Rating	766	767
Financing Receivable With Credit Quality Of Loan Based Upon the Weighted Average Loan-To-Value Ratio	55.90%	55.90%