EMPLOYEE RETIREMENT PLANS - Schedule of fair value hierarchy (Details) - Plan Assets [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	$ 41,036	$ 37,353
Subtotal [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	40,945	37,247
Common stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	17,490	15,160
Preferred stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	316	307
Exchange traded funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	5,213	4,454
Corporate obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	4,626	4,568
State and municipal obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	1,062	1,046
Pooled fixed income funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	7,598	7,767
U.S. government securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	364	286
Marketable CD's [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	806	911
Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	3,470	2,748
Other assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	91	106
Fair Value, Inputs, Level 1 [Member] | Subtotal [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	32,032	28,804
Fair Value, Inputs, Level 1 [Member] | Common stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	15,464	13,556
Fair Value, Inputs, Level 1 [Member] | Preferred stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	287	279
Fair Value, Inputs, Level 1 [Member] | Exchange traded funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	5,213	4,454
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	7,598	7,767
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	3,470	2,748
Fair Value, Inputs, Level 2 [Member] | Subtotal [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	8,913	8,443
Fair Value, Inputs, Level 2 [Member] | Common stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	2,026	1,604
Fair Value, Inputs, Level 2 [Member] | Preferred stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	29	28
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	4,626	4,568
Fair Value, Inputs, Level 2 [Member] | State and municipal obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	1,062	1,046
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	364	286
Fair Value, Inputs, Level 2 [Member] | Marketable CD's [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Pension Plan Assets, Total	806	911
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