EMPLOYEE BENEFIT PLAN - Components of net periodic benefit cost (Details) - Retirement Income Plan - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 247	$ 411
Expected return on plan assets	(377)	(395)
Amortization of net losses	202	246
Net periodic benefit cost	$ 72	$ 262