SEGMENT INFORMATION - Schedule of Segment Revenues from Major Customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	$ 404,800	$ 336,324	$ 788,917	$ 677,942
PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	388,141	321,469	757,037	650,200
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer A | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	76,415	34,880	163,241	60,024
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer B | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	66,422	35,188	97,126	90,008
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer C | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	$ 57,474	$ 50,719	$ 109,687	$ 107,789