Loans (Recorded Investment by Loan Class in Current and Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	$ 5,000	$ 7,994
Investment securities, nonaccrual	6,593	9,286
Current	3,580,246	3,540,628
Total Loans	3,591,839	3,557,908
Nonaccrual with no allowance	5,407	8,616
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	4,416	6,209
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	542	1,554
Greater than 90 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	42	231
Commercial Business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	80	351
Investment securities, nonaccrual	1,555	1,975
Current	734,293	796,083
Total Loans	735,928	798,409
Nonaccrual with no allowance	899	1,502
Commercial Business [Member] \| 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	80	264
Commercial Business [Member] \| 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans		87
Commercial Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	900	848
Investment securities, nonaccrual	885	2,906
Current	1,315,969	1,252,771
Total Loans	1,317,754	1,256,525
Nonaccrual with no allowance	355	2,709
Commercial Mortgage [Member] \| 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	900	822
Commercial Mortgage [Member] \| 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans		26
Residential Real Estate Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	628	1,044
Investment securities, nonaccrual	2,615	2,587
Current	573,389	582,906
Total Loans	576,632	586,537
Nonaccrual with no allowance	2,615	2,587
Residential Real Estate Loans [Member] \| 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	612	984
Residential Real Estate Loans [Member] \| 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	16	60
Residential Real Estate Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	116	55
Investment securities, nonaccrual	280	323
Current	77,377	86,330
Total Loans	77,773	86,708
Nonaccrual with no allowance	280	323
Residential Real Estate Lines [Member] \| 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	116	40
Residential Real Estate Lines [Member] \| 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans		15
Consumer Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	3,145	5,314
Investment securities, nonaccrual	1,250	1,495
Current	864,035	806,007
Total Loans	868,430	812,816
Nonaccrual with no allowance	1,250	1,495
Consumer Indirect [Member] \| 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	2,643	3,966
Consumer Indirect [Member] \| 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	502	1,348
Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	131	382
Investment securities, nonaccrual	8
Current	15,183	16,531
Total Loans	15,322	16,913
Nonaccrual with no allowance	8
Other Consumer [Member] \| 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	65	133
Other Consumer [Member] \| 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	24	18
Other Consumer [Member] \| Greater than 90 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due Loans	$ 42	$ 231

Amount of financing receivable on nonaccrual status with no allowance for credit loss.

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