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PENSION AND OTHER POSTRETIREMENT PLANS - Additional Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost |  |
Investments for long-term growth (as a percent) | 97.00% |
Investments for near-term benefit payments (as a percent) | 3.00% |
Cumulative historical returns for the S&P 500 index (as a percent) | 9.50% |
Cumulative historical returns for the long term corporate bonds (as a percent) | 5.00% |
Pension Benefits |  |
Employee benefits |  |
Accumulated benefit obligation | $ 32,300 | $ 27,400
Amortization from accumulated other comprehensive income into net periodic benefit cost over the next fiscal year |  |
Estimated net loss | 650 |
Estimated prior service credit | 77 |
SERP Benefits |  |
Employee benefits |  |
Accumulated benefit obligation | 6,000 | $ 3,600
Amortization from accumulated other comprehensive income into net periodic benefit cost over the next fiscal year |  |
Estimated net loss | $ 257 |

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