DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Financial Instruments Other than Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial assets [Abstract]
Residential mortgage loans	$ 13,316,282	$ 14,154,737
Carrying Amount [Member]
Financial assets [Abstract]
Residential mortgage loans	2,584	3,817
Lending counterparty investments	5,002	65,002
Financial liabilities [Abstract]
Secured borrowings with initial terms of greater than 120 days	139,101	3,246,177
Unsecured borrowings	98,090	97,986
Fair Value [Member]
Financial assets [Abstract]
Residential mortgage loans	2,600	3,900
Lending counterparty investments	5,002	65,002
Financial liabilities [Abstract]
Secured borrowings with initial terms of greater than 120 days	139,100	3,245,000
Unsecured borrowings	68,800	77,200
Interest Rate Swap Agreements [Member] \| Carrying Amount [Member] \| Portfolio-Related [Member]
Financial assets [Abstract]
Portfolio-related interest rate swap agreements	24,709	7,720
Financial liabilities [Abstract]
Interest rate swap agreements	222	1,051
Interest Rate Swap Agreements [Member] \| Carrying Amount [Member] \| Unsecured Borrowings-Related [Member]
Financial liabilities [Abstract]
Interest rate swap agreements	24,195	25,010
Interest Rate Swap Agreements [Member] \| Fair Value [Member] \| Portfolio-Related [Member]
Financial assets [Abstract]
Portfolio-related interest rate swap agreements	24,709	7,720
Financial liabilities [Abstract]
Interest rate swap agreements	222	1,051
Interest Rate Swap Agreements [Member] \| Fair Value [Member] \| Unsecured Borrowings-Related [Member]
Financial liabilities [Abstract]
Interest rate swap agreements	$ 24,195	$ 25,010

Investments in FHLB stock and other junior notes receivable with lending counterparties.

No definition available.

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- Definition

Fair value portion of FHLB advances and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

+ References

No definition available.

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- Definition

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 210
-SubTopic 20
-Section 50
-Paragraph 3
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Fair value, after the 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 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
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-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226008-175313

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- References

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- Definition

The fair value as of the balance sheet date of firm holdings in mortgages, mortgage backed securities (investment instruments that represent ownership of an undivided interest in a group of mortgages, where principal and interest from the individual mortgages are used to pay investors' principal and interest on the mortgage backed security) and asset-backed securities that are primarily paid from the cash flows of a discrete pool of receivables or other financial assets (such as credit-card receivables), either fixed or revolving, that by their terms convert into cash within a finite time period. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

+ References

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- References

No definition available.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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