Allowance For Loan Losses (Schedule Of Aging Analysis Of Accruing And Non-Accruing Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 3,119,801	$ 3,106,150
Non-accrual	9,590	10,297
Gross loans	3,137,681	3,127,410
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,456,243	1,458,746
Non-accrual	3,331	2,814
Gross loans	1,465,215	1,468,278
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	137,727	138,480
Non-accrual	134	168
Gross loans	138,477	139,499
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	203,468	206,447
Non-accrual	1,063	1,345
Gross loans	204,592	208,484
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,289,722	1,269,520
Non-accrual	5,062	5,970
Gross loans	1,296,304	1,277,576
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	29,549	29,108
Non-accrual	0	0
Gross loans	29,570	29,162
DDA overdrafts
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,092	3,849
Non-accrual	0	0
Gross loans	3,523	4,411
Commercial Industrial Loans And Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Gross loans	1,500,896	1,486,060
30-59 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	6,835	9,631
30-59 days | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	4,353	5,990
30-59 days | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	458	671
30-59 days | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	61	549
30-59 days | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	1,520	1,841
30-59 days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	21	39
30-59 days | DDA overdrafts
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	422	541
60-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	1,364	1,070
60-89 days | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	1,206	709
60-89 days | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	157	88
60-89 days | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	1
60-89 days | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	245
60-89 days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	13
60-89 days | DDA overdrafts
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	1	14
Over 90 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	91	262
Over 90 days | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	82	19
Over 90 days | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	1	92
Over 90 days | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	142
Over 90 days | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Over 90 days | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	2
Over 90 days | DDA overdrafts
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing receivable, recorded investment, past due	$ 8	$ 7