DERIVATIVE INSTRUMENTS - Schedule of Derivatives Outstanding (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Notional	$ 1,553,750,000invest_DerivativeNotionalAmount	$ 1,034,450,000invest_DerivativeNotionalAmount
Fair value, Asset	423,501us-gaap_DerivativeAssets	8,244,355us-gaap_DerivativeAssets
Fair value, Liability	13,445,518us-gaap_DerivativeLiabilities	7,031,033us-gaap_DerivativeLiabilities
Caps 1MO LIB
Derivative [Line Items]
Notional	71,250,000	71,250,000
Fair value, Asset	4
Remaining Maturity	7 months 27 days	1 month 20 days
5-year Swap
Derivative [Line Items]
Notional	496,200,000	45,000,000
Fair value, Asset	108,562	402,719
Fair value, Liability	27,732
Remaining Maturity	3 months	3 months
Term of derivative contract	5 years	5 years
10-year Swap
Derivative [Line Items]
Notional	842,800,000	753,700,000
Fair value, Asset	103,765	7,589,466
Fair value, Liability	8,258,356
Remaining Maturity	3 months	3 months
Term of derivative contract	10 years	10 years
Futures
Derivative [Line Items]
Notional	1,339,000,000	798,700,000
Fair value, Asset	212,327	7,992,185
Fair value, Liability	8,286,088
Swaps 3MO LIB
Derivative [Line Items]
Notional	100,000,000	121,000,000
Fair value, Liability	4,505,444	6,420,495
Remaining Maturity	3 years 2 months 4 days	4 years 6 months 4 days
CMBX
Derivative [Line Items]
Notional	10,000,000	10,000,000
Fair value, Asset	211,170	252,170
Remaining Maturity	6 years 9 months 18 days	8 years 4 months 17 days
CDX
Derivative [Line Items]
Notional	33,500,000	33,500,000
Fair value, Liability	653,986	610,538
Remaining Maturity	3 years 11 months 19 days	4 years 11 months 19 days
Credit Derivatives
Derivative [Line Items]
Notional	43,500,000	43,500,000
Fair value, Asset	211,170	252,170
Fair value, Liability	$ 653,986	$ 610,538

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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Fair value, after the effects of master netting arrangements, of a financial asset or other 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 assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313

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- Definition

Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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