EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Other non-service component of net periodic benefit costs	$ 278	$ (103)	$ 833	$ (305)
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	11,836	10,142	35,508	30,429
Interest cost	1,448	1,084	4,344	3,252
Expected return on plan assets	(2,135)	(1,441)	(6,405)	(4,325)
Amortization of prior service cost	22	13	65	39
Amortization of actuarial loss	71	113	214	339
Net periodic benefit cost	11,242	9,911	33,726	29,734
Post Retirement Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	287	316	861	948
Interest cost	155	172	465	516
Amortization of prior service cost	161	162	484	484
Net periodic benefit cost	$ 603	$ 650	$ 1,810	$ 1,948