COMPONENTS OF QUARTERLY AND YEAR TO DATE NET PERIODIC BENEFIT COSTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Qualified Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost, benefits earned during the period	$ 0	$ 0	$ 0	$ 0
Interest cost on projected benefit obligation	384	403	769	806
Expected return on plan assets	(826)	(785)	(1,652)	(1,570)
Amortization of unrecognized transition obligation	0	0	0	0
Amortization of unrecognized prior service cost	0	0	0	0
Amortization of unrecognized net loss	44	58	87	116
Net periodic pension benefit	(398)	(324)	(796)	(648)
Supplemental Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost, benefits earned during the period	0	0	0	0
Interest cost on projected benefit obligation	12	12	24	24
Expected return on plan assets	0	0	0	0
Amortization of unrecognized prior service cost	0	0	0	0
Amortization of unrecognized net loss	2	1	4	2
Net periodic pension benefit	14	13	28	26
Postretirement Plan, Medical and Life
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost, benefits earned during the period	0	0	0	0
Interest cost on projected benefit obligation	4	4	7	8
Expected return on plan assets	0	0	0	0
Amortization of unrecognized prior service cost	(55)	(55)	(110)	(110)
Amortization of unrecognized net loss	27	29	55	58
Net periodic pension benefit	$ (24)	$ (22)	$ (48)	$ (44)