EMPLOYEE BENEFIT PLAN - Components of net periodic benefit cost (Details) - Retirement Income Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Interest cost	$ 411	$ 490	$ 1,234	$ 1,470
Expected return on plan assets	(395)	(649)	(1,186)	(1,949)
Amortization of net losses	246	229	739	689
Net periodic benefit cost	$ 262	$ 70	$ 787	$ 210