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Loans (Recorded Investment by Loan Class in Current and Nonaccrual Loans) (Details) - USD ($) $ in Thousands | Jun. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | $ 4,461,468 | $ 4,462,139
Financing Receivable, Allowance for Credit Loss, Current | 4,377,897 | 4,360,265
Investment securities, nonaccrual | 25,173 | 26,639
Nonaccrual with no allowance | 19,346 | 21,316
30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 13,952 | 25,268
60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 2,056 | 4,058
Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 36 | 21
Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 16,044 | 29,347
Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 4,419,114 | 4,416,251
Commercial Business [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 713,947 | 735,700
Financing Receivable, Allowance for Credit Loss, Current | 707,164 | 728,942
Investment securities, nonaccrual | 5,680 | 5,664
Nonaccrual with no allowance | 277 | 341
Commercial Business [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 135 | 341
Commercial Business [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 213 | 0
Commercial Business [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 0
Commercial Business [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 348 | 341
Commercial Business [Member] | Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 713,192 | 734,947
Commercial Mortgage [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 2,085,870 | 2,005,319
Financing Receivable, Allowance for Credit Loss, Current | 2,076,195 | 1,992,079
Investment securities, nonaccrual | 10,452 | 10,563
Nonaccrual with no allowance | 10,028 | 10,563
Commercial Mortgage [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 2,371 | 5,900
Commercial Mortgage [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 727
Commercial Mortgage [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 0
Commercial Mortgage [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 2,371 | 6,627
Commercial Mortgage [Member] | Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 2,089,018 | 2,009,269
Residential Real Estate Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 647,675 | 649,822
Financing Receivable, Allowance for Credit Loss, Current | 628,269 | 628,115
Investment securities, nonaccrual | 5,961 | 6,364
Nonaccrual with no allowance | 5,961 | 6,364
Residential Real Estate Loans [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1,370 | 2,614
Residential Real Estate Loans [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 117 | 80
Residential Real Estate Loans [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 0
Residential Real Estate Loans [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1,487 | 2,694
Residential Real Estate Loans [Member] | Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 635,717 | 637,173
Residential Real Estate Lines [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 75,510 | 77,367
Financing Receivable, Allowance for Credit Loss, Current | 71,872 | 73,568
Investment securities, nonaccrual | 183 | 221
Nonaccrual with no allowance | 183 | 221
Residential Real Estate Lines [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 127 | 163
Residential Real Estate Lines [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 20
Residential Real Estate Lines [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 0
Residential Real Estate Lines [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 127 | 183
Residential Real Estate Lines [Member] | Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 72,182 | 73,972
Consumer Indirect [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 894,596 | 948,831
Financing Receivable, Allowance for Credit Loss, Current | 850,642 | 892,577
Investment securities, nonaccrual | 2,897 | 3,814
Nonaccrual with no allowance | 2,897 | 3,814
Consumer Indirect [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 9,817 | 16,128
Consumer Indirect [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1,710 | 3,204
Consumer Indirect [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 0
Consumer Indirect [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 11,527 | 19,332
Consumer Indirect [Member] | Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 865,066 | 915,723
Other Consumer [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 43,870 | 45,100
Financing Receivable, Allowance for Credit Loss, Current | 43,755 | 44,984
Investment securities, nonaccrual | 0 | 13
Nonaccrual with no allowance | 0 | 13
Other Consumer [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 132 | 122
Other Consumer [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 16 | 27
Other Consumer [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 36 | 21
Other Consumer [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 184 | 170
Other Consumer [Member] | Total Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | $ 43,939 | $ 45,167

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