ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts	$ (6,000)	$ (5,000)
Accounts Receivable, Net	154,847	172,367
Customer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	92,000	99,000
Customer | Derivatives
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	5,000	8,000
Customer | Due from Affiliates
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	8,000	8,000
Customer | Customer, Unbilled
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	42,000	45,000
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	$ 19,000	$ 25,000