EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,339	$ 5,789	$ 14,679	$ 11,579
Interest cost	775	707	1,551	1,416
Expected return on plan assets	(1,107)	(829)	(2,213)	(1,659)
Amortization of prior service costs	13	13	26	26
Amortization of loss	194	311	388	622
Net periodic benefit cost	7,214	5,991	14,431	11,984
Post Retirement Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	219	244	439	488
Interest cost	133	134	267	269
Amortization of prior service costs	109	76	218	152
Amortization of loss	0	0	0	0
Net periodic benefit cost	$ 461	$ 454	$ 924	$ 909