BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	$ 1,026	$ 831
Interest cost	1,406	1,375
Expected return on plan assets	(2,960)	(3,042)
Amortization of unrecognized net loss	377	366
Amortization of prior service cost	11	2
Net periodic benefit cost	(140)	(468)
Post-retirement Benefits [Member]
Net periodic benefit cost [Abstract]
Service cost	0	0
Interest cost	20	22
Expected return on plan assets	0	0
Amortization of unrecognized net loss	(1)	(3)
Amortization of prior service cost	(45)	(45)
Net periodic benefit cost	$ (26)	$ (26)