SEGMENT INFORMATION - Schedule of Segment Revenues from Major Customers (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	$ 356,982	$ 384,117
PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	339,164	368,896
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer A | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	61,872	86,826
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer B | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	123,118
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer C | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	$ 41,866	52,213
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer D | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers		$ 39,262