EMPLOYEE BENEFIT PLANS - Net Periodic Pension Cost (Credit) (Details) - United Kingdom - Pension Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 326	$ 426	$ 648	$ 867
Expected return on plan assets	(509)	(558)	(1,012)	(1,135)
Amortization of prior service cost	9	8	17	16
Net periodic pension credit	$ (174)	$ (124)	$ (347)	$ (252)