SEGMENT INFORMATION - Schedule of Segment Revenues from Major Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	$ 313,355	$ 316,113	$ 1,102,272	$ 994,053
PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	297,240	301,048	1,054,277	951,247
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer A | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	46,727		209,968
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer B | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	84,110		181,236	114,451
Sales Revenue, Goods, Net | Customer Concentration Risk | Customer C | PAMC
Revenue, Major Customer [Line Items]
Revenue from contracts with customers	$ 59,364	$ 70,159	$ 169,052	$ 177,948