EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS - Employee benefit plan amounts recognized in the Consolidated Balance Sheets and Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Retirement Benefits [Abstract]
Service cost	$ 1,735	$ 1,239	$ 3,030	$ 2,477
Interest cost	601	589	1,191	1,178
Expected return on plan assets	(2,450)	(2,481)	(4,910)	(4,962)
Amortization of prior service cost	(103)	(104)	(206)	(207)
Defined Benefit Plan, Amortization of Gain (Loss)	555	439	1,077	877
Net periodic benefit cost (income)	$ 338	$ (318)	$ 182	$ (637)