ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts	$ (6,000)	$ (5,000)
Accounts Receivable, Net	196,366	137,932
Customer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	120,000	81,000
Customer | Due from Affiliates
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	6,000	7,000
Customer | Customer, Unbilled
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	61,000	39,000
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	15,000	16,000
Derivatives | Customer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 4,000	$ 9,000