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RETIREMENT AND POSTRETIREMENT PLANS - Employee Retirement Plans investments measured at fair value (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Employee Retirement Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | $ 21,303 | $ 22,593 | $ 28,693
Expected annual rates of return | 7.00% | 7.00% | 7.00%
Percentage of cumulative long term return on index | 9.00% |  |
Percentage of cumulative long term return on bonds | 5.00% |  |
Employee Retirement Plan's target allocation, expected annual rate of return | 7.00% | 7.00% |
Actuarial (gain) loss | $ 384 | $ (5,004) |
Employee Retirement Plan | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 58 | 541 |
Employee Retirement Plan | U.S. large cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 8,398 |
Employee Retirement Plan | U.S. mid cap/small cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 2,348 |
Employee Retirement Plan | International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 2,718 |
Employee Retirement Plan | Equities blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 192 |
Employee Retirement Plan | Corporate |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 1,305 |
Employee Retirement Plan | Government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 21,245 | 2,527 |
Employee Retirement Plan | Mortgage-backed |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 586 |
Employee Retirement Plan | High yield bonds and bond funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 3,978 |
Employee Retirement Plan | Domestic Mid Cap. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 21,303 | 22,593 |
Employee Retirement Plan | Level 1 Inputs | U.S. large cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 8,398 |
Employee Retirement Plan | Level 1 Inputs | U.S. mid cap/small cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 2,348 |
Employee Retirement Plan | Level 1 Inputs | International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 2,718 |
Employee Retirement Plan | Level 1 Inputs | Equities blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 192 |
Employee Retirement Plan | Level 1 Inputs | Government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 21,245 | 2,527 |
Employee Retirement Plan | Level 1 Inputs | Domestic Mid Cap. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 21,245 | 16,183 |
Employee Retirement Plan | Level 2 Inputs | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 58 | 541 |
Employee Retirement Plan | Level 2 Inputs | Corporate |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 1,305 |
Employee Retirement Plan | Level 2 Inputs | Mortgage-backed |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 586 |
Employee Retirement Plan | Level 2 Inputs | High yield bonds and bond funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 3,978 |
Employee Retirement Plan | Level 2 Inputs | Domestic Mid Cap. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 58 | 6,410 |
BNB Bank Pension Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | $ 38,170 | $ 38,572 | $ 47,857
Expected annual rates of return | 7.25% | 7.25% |
Percentage of cumulative long term return on index | 9.00% |  |
Percentage of cumulative long term return on bonds | 5.00% |  |
Employee Retirement Plan's target allocation, expected annual rate of return | 7.25% |  |
Actuarial (gain) loss | $ (883) | $ (7,111) |
BNB Bank Pension Plan | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 317 | 1,001 |
BNB Bank Pension Plan | U.S. large cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 14,310 |
BNB Bank Pension Plan | U.S. mid cap/small cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 4,094 |
BNB Bank Pension Plan | International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 4,658 |
BNB Bank Pension Plan | Equities blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 308 |
BNB Bank Pension Plan | Corporate |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 2,203 |
BNB Bank Pension Plan | Government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 37,853 | 4,275 |
BNB Bank Pension Plan | Mortgage-backed |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 979 |
BNB Bank Pension Plan | High yield bonds and bond funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 6,744 |
BNB Bank Pension Plan | Domestic Mid Cap. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 38,572 |
BNB Bank Pension Plan | Level 1 Inputs |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 37,853 |  |
BNB Bank Pension Plan | Level 1 Inputs | U.S. large cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 14,310 |
BNB Bank Pension Plan | Level 1 Inputs | U.S. mid cap/small cap |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 4,094 |
BNB Bank Pension Plan | Level 1 Inputs | International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 4,658 |
BNB Bank Pension Plan | Level 1 Inputs | Equities blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 308 |
BNB Bank Pension Plan | Level 1 Inputs | Government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 37,853 | 4,275 |
BNB Bank Pension Plan | Level 1 Inputs | Domestic Mid Cap. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 27,645 |
BNB Bank Pension Plan | Level 2 Inputs |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | 317 |  |
BNB Bank Pension Plan | Level 2 Inputs | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets | $ 317 | 1,001 |
BNB Bank Pension Plan | Level 2 Inputs | Corporate |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 2,203 |
BNB Bank Pension Plan | Level 2 Inputs | Mortgage-backed |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 979 |
BNB Bank Pension Plan | Level 2 Inputs | High yield bonds and bond funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | 6,744 |
BNB Bank Pension Plan | Level 2 Inputs | Domestic Mid Cap. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total Plan Assets |  | $ 10,927 |

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- Definition Percentage of cumulative long term return on index in a defined benefit plan. + References No definition available. + Details
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- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a)(4) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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