PENSION PLAN AND OTHER BENEFIT PLANS - Changes in Projected Benefit Obligation and Plan Assets, and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in projected benefit obligation:
Service cost	$ 0	$ 0
Curtailments	0	0
Pension Plan
Change in projected benefit obligation:
Benefit obligation at beginning of year	39,886	36,022
Service cost	0	0	$ 0
Interest cost	1,300	1,522	1,551
Actuarial (gain) loss	3,735	4,474
Settlements	0	0	(3,300)
Benefits paid	(2,140)	(2,132)
Benefit obligation at end of year	42,781	39,886	36,022
Change in plan assets:
Fair value of plan assets at beginning of year	45,557	41,476
Actual return on plan assets	6,717	6,213
Employer contributions	0	0
Settlements	0	0
Benefits paid	(2,140)	(2,132)
Fair value of plan assets at end of year	50,134	45,557	41,476
Funded status of plan	7,353	5,671
Defined Benefit Health Care Plan
Change in projected benefit obligation:
Benefit obligation at beginning of year	332	363
Service cost	0	0	0
Interest cost	9	16	16
Participant contributions	35	49
Amendments	0	0
Actuarial (gain) loss	(57)	31
Benefits paid	(70)	(127)
Benefit obligation at end of year	249	332	363
Change in plan assets:
Fair value of plan assets at beginning of year	0	0
Employer contributions	35	78
Participant contributions	35	49
Benefits paid	(70)	(127)
Fair value of plan assets at end of year	0	0	0
Funded status of plan	(249)	(332)
Executive Supplemental Pension Plan
Change in projected benefit obligation:
Benefit obligation at beginning of year	1,232	1,179
Service cost	0	0	0
Interest cost	39	49	46
Actuarial (gain) loss	89	113
Benefits paid	(109)	(109)
Benefit obligation at end of year	1,251	1,232	1,179
Change in plan assets:
Fair value of plan assets at beginning of year	0	0
Employer contributions	109	109
Benefits paid	(109)	(109)
Fair value of plan assets at end of year	0	0	$ 0
Funded status of plan	$ (1,251)	$ (1,232)