EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5,789	$ 4,851	$ 11,579	$ 9,142
Interest cost	707	601	1,416	1,171
Expected return on plan assets	(829)	(539)	(1,659)	(1,063)
Amortization of prior service costs	13	10	26	12
Amortization of loss	311	258	622	480
Net periodic benefit cost	5,991	5,181	11,984	9,742
Post Retirement Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	244	300	488	478
Interest cost	134	135	269	228
Amortization of prior service costs	76	75	152	55
Amortization of loss	0	1	0	(4)
Net periodic benefit cost	$ 454	$ 511	$ 909	$ 757