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LOANS - Allowance for Credit Losses (Details) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) | Jun. 30, 2020 USD ($) | Dec. 31, 2020 USD ($)
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | $ 55,069 | $ 55,652 | $ 60,869 | $ 49,911 | $ 49,911
Charge-offs | (1,106) | (2,094) | (3,072) |  |
Recoveries | 1,698 | 1,184 | 3,283 |  |
Steuben acquisition |  | 3,662 |  |  |
Provision | (3,911) | 6,033 | (9,330) |  |
Balance, end of period | 51,750 | 64,437 | 51,750 | 64,437 | 60,869
Liabilities for off-balance-sheet credit exposures [Roll Forward] |  |  |  |  |
Beginning balance | 1,189 | 845 | 1,489 | 0 | 0
Charge-offs | 0 | 0 | 0 |  |
Recoveries | 0 | 0 | 0 |  |
Steuben acquisition |  | 67 |  |  |
Provision | (427) | 540 | (727) |  |
Ending balance | 762 | 1,452 | 762 | 1,452 | 1,489
Total allowance for credit losses [Roll Forward] |  |  |  |  |
Beginning balance | 56,258 | 56,497 | 62,358 | 49,911 | 49,911
Charge-offs | (1,106) | (2,094) | (3,072) |  |
Recoveries | 1,698 | 1,184 | 3,283 |  |
Steuben acquisition |  | 3,729 |  |  |
Provision | (4,338) | 6,573 | (10,057) |  |
Ending balance | $ 52,512 | 65,889 | $ 52,512 | 65,889 | $ 62,358
Allowance for Credit Losses |  |  |  |  |
Allowance for credit losses to total loans ratio | 0.71 |  | 0.71 |  |
Basis points lower level |  |  | 0.15 |  | 0.11
Accrued interest and fees receivable | $ 19,000 |  | $ 19,000 |  |
Minimum [Member] | COVID-19 [Member] |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |
Percentage of peak unemployment |  |  | 3.00% |  |
Maximum [Member] | COVID-19 [Member] |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |
Percentage of peak unemployment |  |  | 9.00% |  |
ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 51,268 | $ 51,268
Charge-offs |  |  |  | (5,141) |
Recoveries |  |  |  | 2,681 |
Steuben acquisition |  |  |  | 3,662 |
Provision |  |  |  | 11,967 |
Balance, end of period |  | 64,437 |  | 64,437 |
Liabilities for off-balance-sheet credit exposures [Roll Forward] |  |  |  |  |
Beginning balance |  |  |  | 1,185 | 1,185
Charge-offs |  |  |  | 0 |
Recoveries |  |  |  | 0 |
Steuben acquisition |  |  |  | 67 |
Provision |  |  |  | 200 |
Ending balance |  | 1,452 |  | 1,452 |
Total allowance for credit losses [Roll Forward] |  |  |  |  |
Beginning balance |  |  |  | 52,453 | 52,453
Charge-offs |  |  |  | (5,141) |
Recoveries |  |  |  | 2,681 |
Steuben acquisition |  |  |  | 3,729 |
Provision |  |  |  | 12,167 |
Ending balance |  | 65,889 |  | 65,889 |
ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 1,357 | 1,357
Liabilities for off-balance-sheet credit exposures [Roll Forward] |  |  |  |  |
Beginning balance |  |  |  | 1,185 | 1,185
Total allowance for credit losses [Roll Forward] |  |  |  |  |
Beginning balance |  |  |  | 2,542 | 2,542
Acquired Impaired Loans [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 163 | 163
Acquired Impaired Loans [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 0 | 0
Charge-offs |  |  |  | 0 |
Recoveries |  |  |  | 0 |
Steuben acquisition |  |  |  | 0 |
Provision |  |  |  | 0 |
Balance, end of period |  | 0 |  | 0 |
Acquired Impaired Loans [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | (163) | (163)
Acquired Deteriorated |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 1,996 | 3,046 | $ 1,882 | 0 | 0
Charge-offs | 0 | 0 | 0 |  |
Recoveries | 33 | 48 | 60 |  |
Steuben acquisition |  | 528 |  |  |
Provision | (144) | (61) | (57) |  |
Balance, end of period | 1,885 | 3,561 | 1,885 | 3,561 | 1,882
Acquired Deteriorated | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 3,072 | 3,072
Charge-offs |  |  |  | 0 |
Recoveries |  |  |  | 48 |
Steuben acquisition |  |  |  | 528 |
Provision |  |  |  | (87) |
Balance, end of period |  | 3,561 |  | 3,561 |
Acquired Deteriorated | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 3,072 | 3,072
Commercial Portfolio Segment [Member] | Business Lending [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 27,042 | 19,489 | 28,190 | 19,426 | 19,426
Charge-offs | (2) | (7) | (53) |  |
Recoveries | 255 | 84 | 322 |  |
Steuben acquisition |  | 2,483 |  |  |
Provision | (3,878) | 2,155 | (5,042) |  |
Balance, end of period | 23,417 | 24,204 | 23,417 | 24,204 | 28,190
Commercial Portfolio Segment [Member] | Business Lending [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 19,714 | 19,714
Charge-offs |  |  |  | (183) |
Recoveries |  |  |  | 222 |
Steuben acquisition |  |  |  | 2,483 |
Provision |  |  |  | 1,968 |
Balance, end of period |  | 24,204 |  | 24,204 |
Commercial Portfolio Segment [Member] | Business Lending [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 288 | 288
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 9,686 | 12,430 | 10,672 | 10,269 | 10,269
Charge-offs | (142) | (234) | (242) |  |
Recoveries | 9 | 36 | 19 |  |
Steuben acquisition |  | 146 |  |  |
Provision | 448 | 710 | (448) |  |
Balance, end of period | 10,001 | 13,088 | 10,001 | 13,088 | 10,672
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 9,218 | 9,218
Charge-offs |  |  |  | (420) |
Recoveries |  |  |  | 44 |
Steuben acquisition |  |  |  | 146 |
Provision |  |  |  | 4,100 |
Balance, end of period |  | 13,088 |  | 13,088 |
Residential Portfolio Segment [Member] | Consumer Mortgage [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | (1,051) | (1,051)
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 11,120 | 13,694 | 13,696 | 13,712 | 13,712
Charge-offs | (750) | (1,431) | (2,149) |  |
Recoveries | 1,183 | 833 | 2,429 |  |
Steuben acquisition |  | 183 |  |  |
Provision | (450) | 2,587 | (2,873) |  |
Balance, end of period | 11,103 | 15,866 | 11,103 | 15,866 | 13,696
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 12,715 | 12,715
Charge-offs |  |  |  | (3,510) |
Recoveries |  |  |  | 1,996 |
Steuben acquisition |  |  |  | 183 |
Provision |  |  |  | 4,482 |
Balance, end of period |  | 15,866 |  | 15,866 |
Consumer Portfolio Segment [Member] | Consumer Indirect [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | (997) | (997)
Consumer Portfolio Segment [Member] | Consumer Direct [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 2,682 | 3,737 | 3,207 | 3,255 | 3,255
Charge-offs | (195) | (341) | (513) |  |
Recoveries | 213 | 171 | 444 |  |
Steuben acquisition |  | 87 |  |  |
Provision | (152) | 374 | (590) |  |
Balance, end of period | 2,548 | 4,028 | 2,548 | 4,028 | 3,207
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 2,612 | 2,612
Charge-offs |  |  |  | (874) |
Recoveries |  |  |  | 353 |
Steuben acquisition |  |  |  | 87 |
Provision |  |  |  | 1,850 |
Balance, end of period |  | 4,028 |  | 4,028 |
Consumer Portfolio Segment [Member] | Consumer Direct [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | (643) | (643)
Consumer Portfolio Segment [Member] | Home Equity [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 1,543 | 2,484 | 2,222 | 2,129 | 2,129
Charge-offs | (17) | (81) | (115) |  |
Recoveries | 5 | 12 | 9 |  |
Steuben acquisition |  | 235 |  |  |
Provision | 265 | 40 | (320) |  |
Balance, end of period | 1,796 | 2,690 | 1,796 | 2,690 | 2,222
Consumer Portfolio Segment [Member] | Home Equity [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 2,937 | 2,937
Charge-offs |  |  |  | (154) |
Recoveries |  |  |  | 18 |
Steuben acquisition |  |  |  | 235 |
Provision |  |  |  | (346) |
Balance, end of period |  | 2,690 |  | 2,690 |
Consumer Portfolio Segment [Member] | Home Equity [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 808 | 808
Unallocated Financing Receivables [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period | 1,000 | 772 | 1,000 | 957 | 957
Charge-offs | 0 | 0 | 0 |  |
Recoveries | 0 | 0 | 0 |  |
Steuben acquisition |  | 0 |  |  |
Provision | 0 | 228 | 0 |  |
Balance, end of period | $ 1,000 | 1,000 | $ 1,000 | 1,000 | 1,000
Unallocated Financing Receivables [Member] | ASU 2016-13 [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | 1,000 | 1,000
Charge-offs |  |  |  | 0 |
Recoveries |  |  |  | 0 |
Steuben acquisition |  |  |  | 0 |
Provision |  |  |  | 0 |
Balance, end of period |  | $ 1,000 |  | 1,000 |
Unallocated Financing Receivables [Member] | ASU 2016-13 [Member] | Cumulative Effect Adjustment [Member] |  |  |  |  |
Allowance for loan losses [Roll Forward] |  |  |  |  |
Balance, beginning of period |  |  |  | $ 43 | $ 43

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