RESIDENTIAL MORTGAGE INVESTMENTS - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Schedule of Residential Mortgage Investments [Line Items]
Mortgage securities weighted average contractual maturity, months	290 months
Current-Reset ARMs [Member]
Schedule of Residential Mortgage Investments [Line Items]
Available for sale ARM securities	7,850,000
Agency securities average months to roll, months	6 months 9 days
Current-Reset ARMs [Member] \| Maximum [Member]
Schedule of Residential Mortgage Investments [Line Items]
Agency securities months to roll	18 months
Longer-To-Reset ARMs [Member]
Schedule of Residential Mortgage Investments [Line Items]
Available for sale ARM securities	6,030,000
Agency securities average months to roll, months	40 months
Longer-To-Reset ARMs [Member] \| Minimum [Member]
Schedule of Residential Mortgage Investments [Line Items]
Agency securities months to roll	18 months

The average number of months until coupon reset. Current reset ARM securities have a months to roll of less than 18 months, while longer-to-reset ARM securities have a months to roll of 18 months or greater.

No definition available.

+ Details

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- Definition

The average number of months until coupon reset. Current reset ARM securities have a months to roll of less that 18 months, while longer-to-reset ARM securities have a months to roll of 18 months or greater.

+ References

No definition available.

+ Details

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- Definition

Represents the weighted average contractual maturity period of the portfolio without giving affect to mortgage prepayments.

+ References

No definition available.

+ Details

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- Details

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- Definition

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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Period Type:	instant

- Details

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- Details

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