PENSION AND POST RETIREMENT BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of net periodic pension benefit Gain
Interest and service cost	$ 2,138	$ 2,350	$ 6,414	$ 7,050
Expected return on plan assets	(3,342)	(3,305)	(10,026)	(9,915)
Amortization of net loss	830	816	2,490	2,448
Net periodic loss/(benefit)	$ (374)	$ (139)	$ (1,122)	$ (417)