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ACQUISITIONS - Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands |  |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
May 13, 2022 | Aug. 02, 2021 | Jul. 01, 2021 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Jan. 01, 2022 | Jun. 12, 2020
Consideration : |  |  |  |  |  |  |  |
Cash |  |  |  | $ 85,656 |  |  |  |
Community Bank System, Inc. common stock |  |  |  | 0 |  |  |  |
Contingent consideration |  |  |  | 0 |  |  |  |
Total net consideration |  |  |  | 85,656 |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  | 84,988 |  |  |  |
Investment securities |  |  |  | 11,305 |  |  |  |
Loans |  |  |  | 436,954 |  |  |  |
Premises and equipment, net |  |  |  | 11,317 |  |  |  |
Accrued interest and fees receivable |  |  |  | 884 |  |  |  |
Other assets |  |  |  | 30,007 |  |  |  |
Other intangibles |  |  |  |  |  |  | $ 2,500 |
Deposits |  |  |  | 522,295 |  |  |  |
Other liabilities |  |  |  | (3,541) |  |  |  |
Other Federal Home Loan Bank borrowings |  |  |  | (17,616) |  |  |  |
Subordinated debt held by unconsolidated subsidiary trusts |  |  |  | 0 |  |  |  |
Total identifiable assets, net |  |  |  | 42,987 |  |  |  |
Goodwill |  |  |  | 841,841 | $ 799,109 | $ 793,708 |  |
Core deposit intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Deposits |  |  |  | 7,970 |  |  |  |
Other intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Other intangibles |  |  |  | 3,014 |  |  |  |
Thomas Gregory Associates Insurance Brokers, Inc. |  |  |  |  |  |  |  |
Consideration : |  |  |  |  |  |  |  |
Contingent consideration |  | $ 1,500 |  |  |  |  |  |
Fringe Benefits Design of Minnesota, Inc |  |  |  |  |  |  |  |
Consideration : |  |  |  |  |  |  |  |
Contingent consideration |  |  | $ 1,400 |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Goodwill |  |  | $ 2,100 |  |  |  |  |
Elmira transaction |  |  |  |  |  |  |  |
Consideration : |  |  |  |  |  |  |  |
Cash |  |  |  | 82,179 |  |  |  |
Community Bank System, Inc. common stock |  |  |  | 0 |  |  |  |
Contingent consideration |  |  |  | 0 |  |  |  |
Total net consideration | $ 82,200 |  |  | 82,179 |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  | 84,988 |  |  |  |
Investment securities | 11,300 |  |  | 11,305 |  |  |  |
Loans | 437,000 |  |  | 436,954 |  |  |  |
Premises and equipment, net |  |  |  | 11,303 |  |  |  |
Accrued interest and fees receivable |  |  |  | 884 |  |  |  |
Other assets |  |  |  | 30,007 |  |  |  |
Deposits | 522,300 |  |  | 522,295 |  |  |  |
Other liabilities |  |  |  | (3,541) |  |  |  |
Other Federal Home Loan Bank borrowings |  |  |  | (17,616) |  |  |  |
Subordinated debt held by unconsolidated subsidiary trusts |  |  |  | 0 |  |  |  |
Total identifiable assets, net |  |  |  | 39,959 |  |  |  |
Goodwill | 42,200 |  |  | 42,220 |  |  |  |
Elmira transaction | Core deposit intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Deposits | $ 8,000 |  |  | 7,970 |  |  |  |
Elmira transaction | Other intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Other intangibles |  |  |  | 0 |  |  |  |
Other |  |  |  |  |  |  |  |
Consideration : |  |  |  |  |  |  |  |
Cash |  |  |  | 3,477 |  |  |  |
Community Bank System, Inc. common stock |  |  |  | 0 |  |  |  |
Contingent consideration |  |  |  | 0 |  |  |  |
Total net consideration |  |  |  | 3,477 |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  | 0 |  |  |  |
Investment securities |  |  |  | 0 |  |  |  |
Loans |  |  |  | 0 |  |  |  |
Premises and equipment, net |  |  |  | 14 |  |  |  |
Accrued interest and fees receivable |  |  |  | 0 |  |  |  |
Other assets |  |  |  | 0 |  |  |  |
Deposits |  |  |  | 0 |  |  |  |
Other liabilities |  |  |  | 0 |  |  |  |
Other Federal Home Loan Bank borrowings |  |  |  | 0 |  |  |  |
Subordinated debt held by unconsolidated subsidiary trusts |  |  |  | 0 |  |  |  |
Total identifiable assets, net |  |  |  | 3,028 |  |  |  |
Goodwill |  |  |  | 449 |  |  |  |
Other | Core deposit intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Deposits |  |  |  | 0 |  |  |  |
Other | Other intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Other intangibles |  |  |  | $ 3,014 |  |  |  |
Total |  |  |  |  |  |  |  |
Consideration : |  |  |  |  |  |  |  |
Cash |  |  |  |  | 29,870 |  |  |
Community Bank System, Inc. common stock |  |  |  |  | 0 |  |  |
Contingent consideration |  |  |  |  | 2,900 |  |  |
Total net consideration |  |  |  |  | 32,770 |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  |  | 541 |  |  |
Investment securities |  |  |  |  | 0 |  |  |
Loans |  |  |  |  | 0 |  |  |
Premises and equipment, net |  |  |  |  | 760 |  |  |
Accrued interest and fees receivable |  |  |  |  | 0 |  |  |
Other assets |  |  |  |  | 579 |  |  |
Deposits |  |  |  |  | 0 |  |  |
Other liabilities |  |  |  |  | (1,164) |  |  |
Other Federal Home Loan Bank borrowings |  |  |  |  | 0 |  |  |
Subordinated debt held by unconsolidated subsidiary trusts |  |  |  |  | 0 |  |  |
Total identifiable assets, net |  |  |  |  | 27,053 |  |  |
Goodwill |  |  |  |  | 5,717 |  |  |
Total | Core deposit intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Deposits |  |  |  |  | 0 |  |  |
Total | Other intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Other intangibles |  |  |  |  | $ 26,337 |  |  |
Steuben Trust Corporation |  |  |  |  |  |  |  |
Consideration : |  |  |  |  |  |  |  |
Cash |  |  |  |  |  | 21,613 |  |
Community Bank System, Inc. common stock |  |  |  |  |  | 76,942 |  |
Contingent consideration |  |  |  |  |  | 0 |  |
Total net consideration |  |  |  |  |  | 98,555 |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Cash and cash equivalents |  |  |  |  |  | 55,973 |  |
Investment securities |  |  |  |  |  | 180,497 |  | $ 180,500
Loans |  |  |  |  |  | 339,017 |  | 339,700
Premises and equipment, net |  |  |  |  |  | 7,764 |  |
Accrued interest and fees receivable |  |  |  |  |  | 2,701 |  |
Other assets |  |  |  |  |  | 17,675 |  |
Deposits |  |  |  |  |  | 516,274 |  | (516,300)
Other liabilities |  |  |  |  |  | (4,841) |  |
Other Federal Home Loan Bank borrowings |  |  |  |  |  | (6,000) |  |
Subordinated debt held by unconsolidated subsidiary trusts |  |  |  |  |  | (2,062) |  |
Total identifiable assets, net |  |  |  |  |  | 78,574 |  |
Goodwill |  |  |  |  |  | 19,981 |  | $ 20,000
Steuben Trust Corporation | Core deposit intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Deposits |  |  |  |  |  | 2,928 |  |
Steuben Trust Corporation | Other intangibles |  |  |  |  |  |  |  |
Recognized amounts of identifiable assets acquired and liabilities assumed: |  |  |  |  |  |  |  |
Other intangibles |  |  |  |  |  | $ 1,196 |  |

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