PENSION AND POST RETIREMENT BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest and service cost	$ 1,995	$ 2,138	$ 5,985	$ 6,414
Expected return on plan assets	(3,443)	(3,342)	(10,329)	(10,026)
Amortization of net loss	826	830	2,478	2,490
Net periodic benefit	$ (622)	$ (374)	$ (1,866)	$ (1,122)