Collateral Positions (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Collateral Positions
Assets Pledged	$ 10,698,988	$ 11,410,397
Collateral Held	506,182	507,443
Derivative Hedging Instruments
Collateral Positions
Assets Pledged	149,956	109,142
Derivative Hedging Instruments \| Agency MBS
Collateral Positions
Assets Pledged	34,469	38,569
Derivative Hedging Instruments \| Cash
Collateral Positions
Assets Pledged	115,487	70,573
Repurchase Agreement Borrowings
Collateral Positions
Assets Pledged	10,321,554	9,688,779
Repurchase Agreement Borrowings \| Agency MBS
Collateral Positions
Assets Pledged	3,521,966	2,881,049
Repurchase Agreement Borrowings \| Legacy Non-Agency MBS
Collateral Positions
Assets Pledged	2,545,212	2,818,968
Non-Agency MBS acquired from consolidated VIEs	186,400	570,500
Non-Agency MBS pledged as collateral in connection with contemporaneous repurchase and reverse repurchase agreements entered into with a single counterparty	691,100	726,700
Repurchase Agreement Borrowings \| 3 Year Step-up Securities
Collateral Positions
Assets Pledged	2,523,227	2,625,866
Repurchase Agreement Borrowings \| U.S. Treasury securities
Collateral Positions
Assets Pledged	506,182	507,443
Repurchase Agreement Borrowings \| CRT securities
Collateral Positions
Assets Pledged	320,852	170,352
Repurchase Agreement Borrowings \| Residential Whole Loans
Collateral Positions
Assets Pledged	896,946	684,136
Repurchase Agreement Borrowings \| Cash
Collateral Positions
Assets Pledged	7,169	965
FHLB Advances
Collateral Positions
Assets Pledged	227,478	1,612,476
FHLB Advances \| Agency MBS
Collateral Positions
Assets Pledged	227,478	1,612,476
Reverse Repurchase Agreements
Collateral Positions
Collateral Held	506,182	507,443
Reverse Repurchase Agreements \| U.S. Treasury securities
Collateral Positions
Collateral Held	$ 506,182	$ 507,443

-- None. No documentation exists for this element. --

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- Definition

For an unclassified balance sheet, represents investments in debt and equity securities, categorized neither as held-to-maturity nor trading, which are acquired from a consolidated variable interest entity and eliminated on the entity's consolidated balance sheet.

+ References

No definition available.

+ Details

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- Definition

Represents the non-agency MBS pledged as collateral in connection with contemporaneous repurchase and reverse repurchase agreements entered into with a single counterparty.

+ References

No definition available.

+ Details

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- Definition

The carrying amount, as of the date of the latest financial statement presented, of all assets that are pledged as collateral for the payment of the related debt obligation primarily arising from secured borrowings, repurchase agreements or other current or potential obligations, where the secured party does not have the right by contract or custom to sell or re-pledge the collateral and therefore are not reclassified and separately reported in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

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- Definition

The carrying amount (fair value) as of the balance sheet date of securities held that had been pledged by counterparties under financing and lending arrangements, pursuant to which the entity has the right by agreement or custom to sell or re-pledge such securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5086-111524

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