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LOANS AND ALLOWANCE FOR LOAN LOSSES - Loan Portfolio (Details) - USD ($) $ in Thousands | Mar. 31, 2023 | Dec. 31, 2022 | Mar. 31, 2022 | Dec. 31, 2021
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Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | $ 1,873,701 |  | $ 1,829,448 |  |  |
Allowance for credit losses | (20,075) | [1] | (19,659) | [1] | $ (19,928) | $ (21,025)
Loans, net | 1,853,626 |  | 1,809,789 |  |  |
Construction |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 118,660 |  |  |  |  |
Commercial mortgages, other |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 917,637 |  |  |  |  |
Home equity lines and loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 84,537 |  |  |  |  |
Indirect consumer loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 211,270 |  |  |  |  |
Direct consumer loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 11,146 |  |  |  |  |
Commercial and Agricultural |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 244,507 |  | 252,293 |  |  |
Allowance for credit losses | (4,053) |  | (3,373) |  | (3,483) | (3,591)
Commercial Mortgages |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 1,036,297 |  | 996,913 |  |  |
Allowance for credit losses | (10,983) |  | (11,576) |  | (12,964) | (13,556)
Commercial Mortgages | Construction |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 118,660 |  | 108,243 |  |  |
Commercial Mortgages | Commercial mortgages, other |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 917,637 |  | 888,670 |  |  |
Residential Mortgages |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 285,944 |  | 285,672 |  |  |
Allowance for credit losses | (1,892) |  | (1,845) |  | (1,606) | (1,803)
Consumer Loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 306,953 |  | 294,570 |  |  |
Allowance for credit losses | (3,147) |  | (2,865) |  | $ (1,875) | $ (2,075)
Consumer Loans | Home equity lines and loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 84,537 |  | 81,401 |  |  |
Consumer Loans | Indirect consumer loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 211,270 |  | 202,124 |  |  |
Consumer Loans | Direct consumer loans |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 11,146 |  | 11,045 |  |  |
Commercial and industrial |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 244,174 |  |  |  |  |
Commercial and industrial | Commercial and Agricultural |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 244,174 |  | 252,044 |  |  |
Agricultural |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | 333 |  |  |  |  |
Agricultural | Commercial and Agricultural |  |  |  |  |  |
Composition of loan portfolio [Abstract] |  |  |  |  |  |
Total loans, net of deferred loan fees and costs | $ 333 |  | $ 249 |  |  |
[1] | Effective January 1, 2023, the allowance calculation is based upon Current Expected Credit loss methodology. Prior to January 1, 2023, the allowance calculation was based upon incurred loss methodology. Refer to Note 1 for further discussion.

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