EMPLOYEE RETIREMENT PLANS - Schedule of fair value hierarchy (Details) - Plan Assets [Member] - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019 |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | $ 43,144 | $ 41,036 |
Subtotal [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 43,075 | 40,945 |
Common stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 19,390 | 17,490 |
Preferred stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 272 | 316 |
Exchange traded funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 6,033 | 5,213 |
Corporate obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 4,349 | 4,626 |
State and municipal obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 821 | 1,062 |
Pooled fixed income funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 7,117 | 7,598 |
U.S. government securities [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 763 | 364 |
Marketable CD's [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 513 | 806 |
Cash and cash equivalents [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 3,817 | 3,470 |
Other assets [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 69 | 91 |
Fair Value, Inputs, Level 1 [Member] | Subtotal [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 34,406 | 32,032 |
Fair Value, Inputs, Level 1 [Member] | Common stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 17,194 | 15,464 |
Fair Value, Inputs, Level 1 [Member] | Preferred stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 245 | 287 |
Fair Value, Inputs, Level 1 [Member] | Exchange traded funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 6,033 | 5,213 |
Fair Value, Inputs, Level 1 [Member] | Corporate obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | State and municipal obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Pooled fixed income funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 7,117 | 7,598 |
Fair Value, Inputs, Level 1 [Member] | U.S. government securities [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Marketable CD's [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Cash and cash equivalents [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 3,817 | 3,470 |
Fair Value, Inputs, Level 2 [Member] | Subtotal [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 8,669 | 8,913 |
Fair Value, Inputs, Level 2 [Member] | Common stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 2,196 | 2,026 |
Fair Value, Inputs, Level 2 [Member] | Preferred stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 27 | 29 |
Fair Value, Inputs, Level 2 [Member] | Exchange traded funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | Corporate obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 4,349 | 4,626 |
Fair Value, Inputs, Level 2 [Member] | State and municipal obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 821 | 1,062 |
Fair Value, Inputs, Level 2 [Member] | Pooled fixed income funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | U.S. government securities [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 763 | 364 |
Fair Value, Inputs, Level 2 [Member] | Marketable CD's [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 513 | 806 |
Fair Value, Inputs, Level 2 [Member] | Cash and cash equivalents [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Subtotal [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Common stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Preferred stocks [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Exchange traded funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Corporate obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | State and municipal obligations [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Pooled fixed income funds [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | U.S. government securities [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Marketable CD's [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Cash and cash equivalents [Member] | | |
Defined Benefit Plan Disclosure [Line Items] | | |
Fair Value of Pension Plan Assets, Total | $ 0 | $ 0 |