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Loans (Recorded Investment by Loan Class in Current and Nonaccrual Loans) (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | $ 7,994 | $ 7,081 |
Investment securities, nonaccrual | 9,286 | 8,634 |
Current | 3,540,628 | 3,163,750 |
Total Loans | 3,557,908 | 3,179,465 | $ 3,044,320
Nonaccrual with no allowance | 8,616 |  |
Commercial Business [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 351 | 361 |
Investment securities, nonaccrual | 1,975 | 1,177 |
Current | 796,083 | 569,684 |
Total Loans | 798,409 | 571,222 | 557,040
Nonaccrual with no allowance | 1,502 |  |
Commercial Mortgage [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 848 | 531 |
Investment securities, nonaccrual | 2,906 | 3,146 |
Current | 1,252,771 | 1,104,638 |
Total Loans | 1,256,525 | 1,108,315 | 960,265
Nonaccrual with no allowance | 2,709 |  |
Residential Real Estate Loans [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 1,044 | 1,043 |
Investment securities, nonaccrual | 2,587 | 2,484 |
Current | 582,906 | 557,190 |
Total Loans | 586,537 | 560,717 | 514,981
Nonaccrual with no allowance | 2,587 |  |
Residential Real Estate Lines [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 55 | 268 |
Investment securities, nonaccrual | 323 | 102 |
Current | 86,330 | 100,678 |
Total Loans | 86,708 | 101,048 | 106,712
Nonaccrual with no allowance | 323 |  |
Consumer Indirect [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 5,314 | 4,748 |
Investment securities, nonaccrual | 1,495 | 1,725 |
Current | 806,007 | 815,706 |
Total Loans | 812,816 | 822,179 | 888,732
Nonaccrual with no allowance | 1,495 |  |
Other Consumer [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 382 | 130 |
Current | 16,531 | 15,854 |
Total Loans | 16,913 | 15,984 | $ 16,590
30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 6,209 | 5,897 |
30 to 59 Days Past Due [Member] | Commercial Business [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 264 | 361 |
30 to 59 Days Past Due [Member] | Commercial Mortgage [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 822 | 531 |
30 to 59 Days Past Due [Member] | Residential Real Estate Loans [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 984 | 929 |
30 to 59 Days Past Due [Member] | Residential Real Estate Lines [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 40 | 231 |
30 to 59 Days Past Due [Member] | Consumer Indirect [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 3,966 | 3,729 |
30 to 59 Days Past Due [Member] | Other Consumer [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 133 | 116 |
60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 1,554 | 1,178 |
60 to 89 Days Past Due [Member] | Commercial Business [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 87 |  |
60 to 89 Days Past Due [Member] | Commercial Mortgage [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 26 |  |
60 to 89 Days Past Due [Member] | Residential Real Estate Loans [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 60 | 114 |
60 to 89 Days Past Due [Member] | Residential Real Estate Lines [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 15 | 37 |
60 to 89 Days Past Due [Member] | Consumer Indirect [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 1,348 | 1,019 |
60 to 89 Days Past Due [Member] | Other Consumer [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 18 | 8 |
Greater than 90 Days [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 231 | 6 |
Greater than 90 Days [Member] | Other Consumer [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | $ 231 | $ 6 |

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