FINANCIAL INSTRUMENTS Schedule of Gross and Net Amounts of Derivative Instruments and Cash Collateral (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Instruments [Abstract]
Financial contracts receivable, Gross amounts of recognized assets (liabilities)	$ 12,893	$ 76,381
Financial contracts receivable, Gross amounts offset in the balance sheet	0	0
Financial contracts receivable, Net amounts of assets (liabilities) presented in the balance sheet	12,893	76,381
Financial contracts receivable, financial instruments available for offset	5,128	938
Financial contracts receivable, Cash collateral (received) pledged	1,336	44,572
Financial contracts receivable, Net amount of asset (liability)	6,429	30,871
Financial contracts payable, Gross amounts of recognized assets (liabilities)	(22,222)	(2,237)
Financial contracts payable, Gross amounts offset in the balance sheet	0	0
Financial contracts payable, Net amounts of assets (liabilities) presented in the balance sheet	(22,222)	(2,237)
Financial contracts payable, financial instruments available for offset	5,128	938
Financial contracts payable, Cash collateral (received) pledged	17,094	1,299
Financial contracts payable, Net amount of asset (liability)	$ 0	$ 0