RETIREMENT PLANS, COSTS OF RETIREMENT PLANS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
401(k) plan expense	$ 374	$ 359	$ 346
Qualified noncontributory defined benefit retirement plan
Defined Benefit Plan Disclosure [Line Items]
Plan expense	$ 1,054	$ 969	$ 984