DERIVATIVE INSTRUMENTS - Schedule of Realized Gains (Losses) on Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Unrealized Gain/(Loss)	$ (621)	$ (984)	$ 889	$ 1,356
Realized Gain/(Loss)	(8,844)	8,099	(36,845)	27,800
Net Result from Derivative Transactions	(9,465)	7,115	(35,956)	29,156
Futures
Derivative [Line Items]
Unrealized Gain/(Loss)	(618)	(940)	892	(52)
Realized Gain/(Loss)	(8,868)	8,099	(36,761)	28,985
Net Result from Derivative Transactions	(9,486)	7,159	(35,869)	28,933
Swaps
Derivative [Line Items]
Unrealized Gain/(Loss)		0		1,403
Realized Gain/(Loss)		0		(848)
Net Result from Derivative Transactions		0		555
Credit Derivatives
Derivative [Line Items]
Unrealized Gain/(Loss)	(3)	(44)	(3)	5
Realized Gain/(Loss)	24	0	(84)	(337)
Net Result from Derivative Transactions	$ 21	$ (44)	$ (87)	$ (332)

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, held at each balance sheet date, that was included in earnings for the period.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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