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LOANS, Amount of Business Lending Loans by Credit Quality Category (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | $ 6,890,543 | $ 6,281,121
Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 5,450,592 | 5,027,984
Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,439,951 | 1,253,137
Business Lending [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 2,775,876 | 2,396,977
Business Lending [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,856,585 | 1,618,827
Business Lending [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 919,291 | 778,150
Business Lending [Member] | Pass [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 2,487,973 | 2,141,830
Business Lending [Member] | Pass [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,655,280 | 1,439,337
Business Lending [Member] | Pass [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 832,693 | 702,493
Business Lending [Member] | Special Mention [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 144,277 | 145,172
Business Lending [Member] | Special Mention [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 98,953 | 105,065
Business Lending [Member] | Special Mention [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 45,324 | 40,107
Business Lending [Member] | Classified [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 131,829 | 102,950
Business Lending [Member] | Classified [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 102,352 | 74,425
Business Lending [Member] | Classified [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 29,477 | 28,525
Business Lending [Member] | Doubtful [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 0 | 1,579
Business Lending [Member] | Doubtful [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 0 | 0
Business Lending [Member] | Doubtful [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 0 | 1,579
Business Lending [Member] | Acquired Impaired [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 11,797 | 5,446
Business Lending [Member] | Acquired Impaired [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 0 | 0
Business Lending [Member] | Acquired Impaired [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 11,797 | 5,446
All Other Loans [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 3,594,007 | 3,409,157
All Other Loans [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 520,660 | 474,987
All Other Loans [Member] | Performing [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 3,579,851 | 3,395,920
All Other Loans [Member] | Performing [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 517,264 | 471,774
All Other Loans [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 14,156 | 13,237
All Other Loans [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 3,396 | 3,213
Consumer Mortgage [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,996,716 | 1,848,450
Consumer Mortgage [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 434,186 | 386,958
Consumer Mortgage [Member] | Performing [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,984,533 | 1,837,185
Consumer Mortgage [Member] | Performing [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 431,523 | 384,336
Consumer Mortgage [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 12,183 | 11,265
Consumer Mortgage [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 2,663 | 2,622
Consumer Indirect [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,107,308 | 1,072,392
Consumer Indirect [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 5,754 | 10,815
Consumer Indirect [Member] | Performing [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,107,183 | 1,072,134
Consumer Indirect [Member] | Performing [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 5,723 | 10,781
Consumer Indirect [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 125 | 258
Consumer Indirect [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 31 | 34
Consumer Direct [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 175,976 | 175,774
Consumer Direct [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 8,402 | 3,046
Consumer Direct [Member] | Performing [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 175,900 | 175,726
Consumer Direct [Member] | Performing [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 8,350 | 3,042
Consumer Direct [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 76 | 48
Consumer Direct [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 52 | 4
Home Equity [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 314,007 | 312,541
Home Equity [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 72,318 | 74,168
Home Equity [Member] | Performing [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 312,235 | 310,875
Home Equity [Member] | Performing [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 71,668 | 73,615
Home Equity [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | 1,772 | 1,666
Home Equity [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Business Lending Loans by Credit Quality Category [Abstract] |  |
Loans | $ 650 | $ 553

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