EMPLOYEE BENEFIT PLANS (Changes in Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 66,576	$ 45,005
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	53,350	30,215
Service cost	19,407	14,794	11,437
Interest cost	2,404	992	502
Plan amendments	529	0
Benefit payments	(2,634)	(663)
Actuarial loss (gain)	8,042	8,012
Projected benefit obligation at end of year	81,098	53,350	30,215
Change in plan assets:
Fair value of plan assets at beginning of year	25,050	10,232
Actual return on plan assets	1,822	33
Benefits paid	(2,634)	(663)
Employer contributions	16,718	15,448
Fair value of plan assets at end of year	40,956	25,050	10,232
Reconciliation of funded status:
Fair value of plan assets at end of year	40,956	25,050	10,232
Less benefit obligation at end of year	81,098	53,350	30,215
Funded status at end of year	(40,142)	(28,300)
Post Retirement Medical Plan [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	8,225	9,730
Service cost	1,099	726	633
Interest cost	520	334	395
Plan amendments	3,911	(860)
Benefit payments	(215)	(51)
Actuarial loss (gain)	1,200	(1,654)
Projected benefit obligation at end of year	14,740	8,225	9,730
Change in plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Benefits paid	(215)	(51)
Employer contributions	215	51
Fair value of plan assets at end of year	0	0	0
Reconciliation of funded status:
Fair value of plan assets at end of year	0	0	0
Less benefit obligation at end of year	14,740	8,225	9,730
Funded status at end of year	$ (14,740)	$ (8,225)