EMPLOYEE BENEFIT PLANS - Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Projected benefit obligation:
Beginning of year	$ 92,407	$ 84,559
Service cost	0	0	$ 77
Interest cost	1,764	2,323	2,303
Actuarial (gain) loss	8,717	8,425
Benefits paid	(6,288)	(6,050)
Prior service cost	0	0	669
Disposal of Norwegian Plan	0	0
Foreign currency translation adjustment and other	3,644	3,150
End of year	100,244	92,407	84,559
Fair value of plan assets:
Beginning of year	83,086	73,619
Actual gain (loss) on plan assets	10,854	10,393
Employer contributions	3,851	2,295
Benefits paid	(6,288)	(6,050)
Foreign currency translation adjustment and other	3,459	2,829
End of year	94,962	83,086	$ 73,619
Excess projected obligation under (over) fair value of plan assets at end of year	(5,282)	(9,321)
Amounts recognized in accumulated other comprehensive loss:
Net actuarial loss	(7,347)	(7,365)
Prior service cost	(674)	(656)
Total	$ (8,021)	$ (8,021)