RETIREMENT PLANS - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Pension Plans
Components of the plan's net periodic pension cost
Service cost	$ 423	$ 447	$ 846	$ 895
Interest cost	879	841	1,758	1,682
Expected return on plan assets	(1,158)	(1,263)	(2,316)	(2,527)
Actuarial (gain)/ loss	(7)	7	(14)	15
Net periodic pension expense	137	32	274	65
Company contributions			700
Funded status of plan
Plan Net Assets					$ 15,600
Projected benefit obligation					$ 15,100
Postretirement Benefits
Components of the plan's net periodic pension cost
Service cost	32	37	64	74
Interest cost	45	40	90	80
Actuarial (gain)/ loss	(15)	(17)	(30)	(34)
Net periodic pension expense	$ 62	$ 60	$ 124	$ 120