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BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES (Details) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Oct. 31, 2023 USD ($) | Dec. 31, 2023 USD ($) item segment subsidiary | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Property, Plant and Equipment |  |  |  |
Number of investment subsidiaries (subsidiary) | subsidiary |  | 2 |  |
Number of branches entity operates (branches) |  | 70 |  |
Number of loan production offices |  | 6 |  |
Transfer to other real estate | $ |  | $ 88,000 | $ 570,000 | $ 43,000
Impairment of goodwill | $ | $ 0 |  |  |
Repayment of deferred fees and interest in years |  | 10 years |  |
Expenses for deferred compensation | $ |  | $ 49,000 | 78,000 | 117,000
Allowance for credit losses on unfunded commitments | $ |  | 2,000,000.0 | 2,100,000 |
Compensation expense | $ |  | 0 | 0 | 0
Deferred compensation liability, current | $ |  | $ 1,100,000 | 1,200,000 |
Incentive award, payment period |  | 15 years |  |
Compensation liability | $ |  | $ 3,800,000 | 4,800,000 |
Short term portion, payment period |  | 75 days |  |
Vesting period |  | 3 years |  |
Long term portion, payment period |  | 75 days |  |
Officers' compensation expense | $ |  | $ 2,900,000 | 2,000,000.0 | 2,300,000
Deferred compensation liability incentive plan | $ |  | $ 1,800,000 | 1,600,000 |
Likelihood of unfavorable settlement (percent) |  | 50.00% |  |
Number of reportable segments | segment |  | 1 |  |
Minimum |  |  |  |
Property, Plant and Equipment |  |  |  |
Finite-lived intangible asset, useful life |  | 10 years |  |
Maximum |  |  |  |
Property, Plant and Equipment |  |  |  |
Finite-lived intangible asset, useful life |  | 12 years |  |
Furniture and Fixtures | Minimum |  |  |  |
Property, Plant and Equipment |  |  |  |
Property, plant and equipment, estimated useful lives |  | 3 years |  |
Furniture and Fixtures | Maximum |  |  |  |
Property, Plant and Equipment |  |  |  |
Property, plant and equipment, estimated useful lives |  | 5 years |  |
Buildings And Leasehold Improvements | Minimum |  |  |  |
Property, Plant and Equipment |  |  |  |
Property, plant and equipment, estimated useful lives |  | 33 years |  |
Buildings And Leasehold Improvements | Maximum |  |  |  |
Property, Plant and Equipment |  |  |  |
Property, plant and equipment, estimated useful lives |  | 39 years |  |
Vigo County |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 7 |  |
Daviess County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Clay County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 3 |  |
Greene County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Knox County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Parke County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Putnam County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Sullivan County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Vanderburgh County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Allen County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Monroe County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Vermillion County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 3 |  |
Champaign County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of loan production offices |  | 4 |  |
Clark County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Coles County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Crawford County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Franklin County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Jasper County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Lawrence County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Livingston County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Marion County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
McLean County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Richland County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Vermilion County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 5 |  |
Wayne County, Illinois |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Calloway County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Breckinridge County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Christian County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 3 |  |
Fulton County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Hancock County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Hopkins County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Marshall County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 2 |  |
Todd County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Trigg County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Warren County, Kentucky |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Cheatham County, Tennessee |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 3 |  |
Montgomery County, Tennessee |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 3 |  |
Hamilton County, Indiana |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Rutherford County, Tennessee |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
Williamson County, Tennessee |  |  |  |
Property, Plant and Equipment |  |  |  |
Number of branches entity operates (branches) |  | 1 |  |
First Financial Bank |  |  |  |
Property, Plant and Equipment |  |  |  |
Investments in subsidiaries | $ |  | $ 1,000,000,000.0 |  |
Service fees |  |  |  |
Property, Plant and Equipment |  |  |  |
Revenue within scope of ASC 606 | $ |  | $ 1,300,000 | $ 1,400,000 | $ 1,300,000

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