Allowance For Loan Losses (Schedule Of Non-Commercial Loans By Payment Performance) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total	$ 3,105,912	$ 3,046,226
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total	1,465,942	1,451,462
Residential real estate | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,463,386	1,447,087
Residential real estate | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	2,556	4,375
Home equity
Financing Receivable, Recorded Investment [Line Items]
Total	139,702	141,965
Home equity | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	139,610	141,834
Home equity | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	92	131
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total	30,323	32,545
Consumer | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	30,323	32,545
Consumer | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
DDA overdrafts
Financing Receivable, Recorded Investment [Line Items]
Total	4,317	5,071
DDA overdrafts | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	4,317	5,071
DDA overdrafts | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
Total
Financing Receivable, Recorded Investment [Line Items]
Total	1,640,284	1,631,043
Total | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,637,636	1,626,537
Total | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	$ 2,648	$ 4,506