SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN - Components of Net Periodic Pension Cost (Details) - Supplemental Executive Retirement Plan [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Components of net periodic pension cost [Abstract]
Service cost	$ 325	$ 302	$ 650	$ 603
Interest cost	262	252	524	494
Amortization of prior service cost	421	415	842	830
Amortization of loss	118	114	236	161
Total net periodic benefit cost	$ 1,126	$ 1,083	$ 2,252	$ 2,088