EMPLOYEE BENEFIT PLANS - Net Periodic Pension Cost (Credit) (Details) - U.K. Plan - Pension Plan - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 322	$ 441
Expected return on plan assets	(503)	(578)
Amortization of prior service cost	9	8
Net periodic pension credit	$ (173)	$ (129)