EMPLOYEE BENEFITS (Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan [Member]
Net periodic benefit cost
Service cost	$ 6,675	$ 5,210	$ 6,300
Interest cost	5,999	5,874	5,175
Expected return on plan assets	(7,800)	(6,956)	(5,772)
Amortization of net loss	4,546	2,174	4,989
Net periodic benefit cost	9,420	6,302	10,692
Postretirement Benefit Plan [Member]
Net periodic benefit cost
Service cost	5,220	3,696	3,875
Interest cost	2,856	2,342	1,759
Expected return on plan assets	0	0	0
Amortization of net loss	2,920	898	879
Net periodic benefit cost	$ 10,996	$ 6,936	$ 6,513