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FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Debt (Details) $ in Thousands | Sep. 30, 2021 USD ($) | Dec. 31, 2020 USD ($)
--- | --- | ---
Carrying value |  |
Fair value disclosure |  |
Financial instruments | $ 265,370 | $ 305,623
Fair value disclosure |  |
Fair value disclosure |  |
Financial instruments | 270,407 | 312,749
Credit Facility | Carrying value | Level 2 |  |
Fair value disclosure |  |
Financial instruments | 50,000 | 70,000
Credit Facility | Fair value disclosure | Level 2 |  |
Fair value disclosure |  |
Financial instruments | 50,000 | 70,000
Notes payable | Carrying value | Level 2 |  |
Fair value disclosure |  |
Financial instruments | 194,439 | 214,216
Notes payable | Fair value disclosure | Level 2 |  |
Fair value disclosure |  |
Financial instruments | $ 196,840 | $ 217,226
New England Pension Fund withdrawal liability | Discount Rate |  |
Fair value disclosure |  |
Measurement input | 0.031 | 0.026
New England Pension Fund withdrawal liability | Carrying value | Level 2 |  |
Fair value disclosure |  |
Financial instruments | $ 20,931 | $ 21,407
New England Pension Fund withdrawal liability | Fair value disclosure | Level 2 |  |
Fair value disclosure |  |
Financial instruments | $ 23,567 | $ 25,523

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