DERIVATIVE INSTRUMENTS HEDGING AND NON-HEDGING ACTIVITIES - Fair Value and Notional Amounts (Details)	Mar. 31, 2018 USD ($) contract	Dec. 31, 2017 USD ($) contract
Derivative Assets
Number of contracts \| contract	13,505	14,355
Fair value	$ 18,132,700	$ 5,349,613
Notional	$ 13,505,000,000	$ 14,355,000,000
Derivative Liabilities
Number of contracts \| contract	0	0
Fair value	$ 0	$ 0
Notional	$ 0	$ 0
Eurodollar Futures (Short positions)
Derivative Assets
Number of contracts \| contract	13,505	14,355
Fair value	$ 18,132,700	$ 5,349,613
Notional	$ 13,505,000,000	$ 14,355,000,000
Derivative Liabilities
Number of contracts \| contract	0	0
Fair value	$ 0	$ 0
Notional	$ 0	$ 0

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

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-Section 50
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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Nominal or face amount used to calculate payments on the derivative liability.

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