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EMPLOYEE BENEFITS - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employee stock ownership plan, maximum employer contribution as a percentage of participant's qualified compensation | 5.00% |  |
Employee stock ownership plan, total contributions accrued or paid | $ 1,270 | $ 1,125 | $ 965
Employee stock ownership plan, shares held under plan (in shares) | 1,224,697 | 1,333,504 |
Employee stock ownership plan, unallocated shares (in shares) | 0 | 0 |
Cash surrender value of life insurance | $ 34,495 | $ 26,301 |
Bonus expense | 3,265 | 2,943 | 2,316
Executive Incentive Retirement Plan | Postretirement Life Insurance | Nonqualified Plan | Unfunded Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Cash surrender value of life insurance | 34,495 | 26,301 |
Plan cost | 602 | 502 | $ 447
Plan obligation | $ 4,081 | $ 3,667 |

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