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Loans (Recorded Investment by Loan Class in Current and Nonaccrual Loans) (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019 | Sep. 30, 2019
--- | --- | --- | ---
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | $ 5,226 | $ 7,081 |
Investment securities, nonaccrual | 10,762 | 8,634 |
Current | 3,516,886 | 3,163,750 |
Total Loans | 3,532,874 | 3,179,465 | $ 3,114,733
Nonaccrual with no allowance | 8,831 |  |
30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 4,462 | 5,897 |
60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 623 | 1,178 |
Greater than 90 Days [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 141 | 6 |
Commercial Business [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 141 | 361 |
Investment securities, nonaccrual | 2,628 | 1,177 |
Current | 820,842 | 569,684 |
Total Loans | 823,611 | 571,222 | 573,610
Nonaccrual with no allowance | 894 |  |
Commercial Business [Member] | 30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 139 | 361 |
Commercial Business [Member] | 60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 2 |  |
Commercial Mortgage [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans |  | 531 |
Investment securities, nonaccrual | 3,372 | 3,146 |
Current | 1,200,981 | 1,104,638 |
Total Loans | 1,204,353 | 1,108,315 | 1,037,304
Nonaccrual with no allowance | 3,175 |  |
Commercial Mortgage [Member] | 30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans |  | 531 |
Residential Real Estate Loans [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 424 | 1,043 |
Investment securities, nonaccrual | 3,305 | 2,484 |
Current | 580,234 | 557,190 |
Total Loans | 583,963 | 560,717 | 547,839
Nonaccrual with no allowance | 3,305 |  |
Residential Real Estate Loans [Member] | 30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 389 | 929 |
Residential Real Estate Loans [Member] | 60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 35 | 114 |
Residential Real Estate Lines [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 288 | 268 |
Investment securities, nonaccrual | 207 | 102 |
Current | 90,404 | 100,678 |
Total Loans | 90,899 | 101,048 | 104,545
Nonaccrual with no allowance | 207 |  |
Residential Real Estate Lines [Member] | 30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 288 | 231 |
Residential Real Estate Lines [Member] | 60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans |  | 37 |
Consumer Indirect [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 4,086 | 4,748 |
Investment securities, nonaccrual | 1,244 | 1,725 |
Current | 808,015 | 815,706 |
Total Loans | 813,345 | 822,179 | 834,968
Nonaccrual with no allowance | 1,244 |  |
Consumer Indirect [Member] | 30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 3,520 | 3,729 |
Consumer Indirect [Member] | 60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 566 | 1,019 |
Other Consumer [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 287 | 130 |
Investment securities, nonaccrual | 6 |  |
Current | 16,410 | 15,854 |
Total Loans | 16,703 | 15,984 | $ 16,467
Nonaccrual with no allowance | 6 |  |
Other Consumer [Member] | 30 to 59 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 126 | 116 |
Other Consumer [Member] | 60 to 89 Days Past Due [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | 20 | 8 |
Other Consumer [Member] | Greater than 90 Days [Member] |  |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |  |
Past Due Loans | $ 141 | $ 6 |

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