EMPLOYEE BENEFIT PLANS - Change in PBO and Assets and Reconciliations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts Recognized in the Consolidated Balance Sheets Consist of::
Noncurrent liabilities	$ (23,344)	$ (25,311)
Pension Benefits
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	90,261	79,559
Service cost	0	0	$ 0
Interest cost	2,706	3,197	3,021
Actuarial loss (gain)	10,915	10,828
Benefits paid	(3,413)	(3,323)
Projected benefit obligation at end of year	100,469	90,261	79,559
Change in Plan Assets
Fair value of plan assets at beginning of year	66,460	50,949
Actual return on plan assets	13,329	12,975
Employer contributions	3,005	6,413
Benefits paid	(3,413)	(3,284)
Other expense	(498)	(593)
Fair value of plan assets at end of year	78,883	66,460	50,949
Funded Status at End of Year:
Net accrued benefit cost	(21,586)	(23,801)
Amounts Recognized in the Consolidated Balance Sheets Consist of::
Current liabilities	(86)	(86)
Noncurrent liabilities	(21,500)	(23,715)
Net amount recognized	(21,586)	(23,801)
Postretirement
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	1,634	1,303
Service cost	6	6	7
Interest cost	51	54	38
Actuarial loss (gain)	209	285
Benefits paid	(14)	(14)
Projected benefit obligation at end of year	1,886	1,634	1,303
Change in Plan Assets
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	14	14
Benefits paid	(14)	(14)
Other expense	0	0
Fair value of plan assets at end of year	0	0	$ 0
Funded Status at End of Year:
Net accrued benefit cost	(1,886)	(1,634)
Amounts Recognized in the Consolidated Balance Sheets Consist of::
Current liabilities	(41)	(38)
Noncurrent liabilities	(1,845)	(1,596)
Net amount recognized	$ (1,886)	$ (1,634)