SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN - Components of Net Periodic Pension Cost (Details) - Supplemental Executive Retirement Plan [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Components of net periodic pension cost [Abstract]
Service cost	$ 428	$ 273
Interest cost	291	321
Amortization of prior service cost	275	275
Amortization of loss	1,234	545
Total net periodic benefit cost	$ 2,228	$ 1,414