EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10,900	$ 11,800	$ 21,800	$ 23,600
Interest cost	2,100	1,400	4,200	2,800
Expected return on plan assets	(2,400)	(2,100)	(4,800)	(4,200)
Amortization of prior service cost and actuarial loss	0	100	100	200
Net periodic benefit cost	10,600	11,200	21,300	22,400
Post Retirement Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	300	200	500	500
Interest cost	100	300	300	400
Amortization of prior service cost and actuarial loss	200	100	300	300
Net periodic benefit cost	$ 600	$ 600	$ 1,100	$ 1,200