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ACCUMULATED OTHER COMPREHENSIVE INCOME OR LOSS (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance | $ 182,627 | $ 165,029 | $ 149,813
Other comprehensive income before reclassification | 8,136 | 5,561 | (1,559)
Amounts reclassified from accumulated other comprehensive income (loss) | 64 | 51 | 690
Total other comprehensive income (loss) | 8,200 | 5,612 | (869)
Ending balance | 199,699 | 182,627 | 165,029
Realized gains on securities available for sale | 0 | 19 | 0
Income tax expense | 4,607 | 3,434 | 4,009
Pension and other employee benefits | 5,553 | 5,902 | 5,524
Net of tax | 19,262 | 15,609 | 19,626
Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | 149,651
Reclassification out of Accumulated Other Comprehensive Income (loss) |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Net of tax | 65 | 51 | 690
Total |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance | (5,799) | (11,411) | (10,340)
Total other comprehensive income (loss) | 8,200 | 5,612 | (869)
Ending balance | 2,401 | (5,799) | (11,411)
Total | Cumulative Effect, Period of Adoption, Adjustment |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | (202)
Total | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | (10,542)
Total | Reclassification out of Accumulated Other Comprehensive Income (loss) |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Net of tax | 0 | (14) | 0
Unrealized Gains and Losses on Securities Available for Sale |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance | 1,368 | (4,646) | (3,415)
Other comprehensive income before reclassification | 7,759 | 6,028 | (1,029)
Amounts reclassified from accumulated other comprehensive income (loss) | 0 | (14) | 0
Total other comprehensive income (loss) | 7,759 | 6,014 | (1,029)
Ending balance | 9,127 | 1,368 | (4,646)
Unrealized Gains and Losses on Securities Available for Sale | Cumulative Effect, Period of Adoption, Adjustment |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | (202)
Unrealized Gains and Losses on Securities Available for Sale | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | (3,617)
Unrealized Gains and Losses on Securities Available for Sale | Reclassification out of Accumulated Other Comprehensive Income (loss) |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Realized gains on securities available for sale | 0 | (19) | 0
Income tax expense | 0 | 5 | 0
Defined Benefit and Other Benefit Plans |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance | (7,167) | (6,765) | (6,925)
Other comprehensive income before reclassification | 377 | (467) | (530)
Amounts reclassified from accumulated other comprehensive income (loss) | 64 | 65 | 690
Total other comprehensive income (loss) | 441 | (402) | 160
Ending balance | (6,726) | (7,167) | (6,765)
Defined Benefit and Other Benefit Plans | Cumulative Effect, Period of Adoption, Adjustment |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | 0
Defined Benefit and Other Benefit Plans | Cumulative Effect, Period of Adoption, Adjusted Balance |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Beginning balance |  |  | (6,925)
Defined Benefit and Other Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income (loss) |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Income tax expense | (15) | (27) | (236)
Net of tax | 65 | 65 | 690
Net Prior Service Cost (Credit) | Reclassification out of Accumulated Other Comprehensive Income (loss) |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Pension and other employee benefits | (220) | (220) | (220)
Net Unamortized Gain (Loss) | Reclassification out of Accumulated Other Comprehensive Income (loss) |  |  |
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward] |  |  |
Pension and other employee benefits | $ 300 | $ 312 | $ 1,146

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