Allowance For Loan Losses (Schedule Of Non-Commercial Loans By Payment Performance) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total	$ 3,155,468	$ 3,127,410
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total	1,472,916	1,468,278
Residential real estate | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,469,052	1,465,445
Residential real estate | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	3,864	2,833
Home equity
Financing Receivable, Recorded Investment [Line Items]
Total	139,245	139,499
Home equity | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	139,013	139,239
Home equity | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	232	260
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total	31,137	29,162
Consumer | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	31,137	29,162
Consumer | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
DDA overdrafts
Financing Receivable, Recorded Investment [Line Items]
Total	3,994	4,411
DDA overdrafts | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,994	4,411
DDA overdrafts | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
Total
Financing Receivable, Recorded Investment [Line Items]
Total	1,647,292	1,641,350
Total | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,643,196	1,638,257
Total | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	$ 4,096	$ 3,093