Allowance For Loan Losses (Schedule Of Non-Commercial Loans By Payment Performance) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total	$ 3,146,697	$ 3,127,410
Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Total	1,485,823	1,468,278
Residential real estate | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,482,771	1,465,445
Residential real estate | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	3,052	2,833
Home equity
Financing Receivable, Recorded Investment [Line Items]
Total	143,540	139,499
Home equity | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	143,531	139,239
Home equity | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	9	260
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total	31,869	29,162
Consumer | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	31,869	29,162
Consumer | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
DDA overdrafts
Financing Receivable, Recorded Investment [Line Items]
Total	3,598	4,411
DDA overdrafts | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,598	4,411
DDA overdrafts | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	0	0
Total
Financing Receivable, Recorded Investment [Line Items]
Total	1,664,830	1,641,350
Total | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,661,769	1,638,257
Total | Non-Performing
Financing Receivable, Recorded Investment [Line Items]
Total	$ 3,061	$ 3,093