PENSION PLANS - Financial information relating to pension plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CHANGE IN BENEFIT OBLIGATION:
Net benefit obligation - beginning of period	$ 13,668	$ 14,620
Interest cost	644	666	$ 697
Actuarial (gain) loss	410	(630)
Gross benefits paid	(789)	(988)
Net benefit obligation - end of period	13,933	13,668	14,620
CHANGE IN PLAN ASSETS:
Fair value of plan assets - beginning of period	10,852	12,120
Employer contributions	400	470
Gross benefits paid	(789)	(988)
Return (loss) on plan assets	2,546	(750)
Fair value of plan assets - end of period	13,009	10,852	$ 12,120
Un-funded status at end of period	$ (924)	$ (2,816)