Collateral Positions (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Collateral Positions
Assets Pledged	$ 11,791,563,000	$ 10,058,769,000
Collateral Held	506,861,000	512,105,000
Derivative contracts
Collateral Positions
Assets Pledged	152,876,000	123,733,000
Derivative contracts \| Agency Mortgage Backed Securities
Collateral Positions
Assets Pledged	60,346,000	57,247,000
Derivative contracts \| Cash
Collateral Positions
Assets Pledged	92,530,000	66,486,000
Repurchase Agreement Borrowings
Collateral Positions
Assets Pledged	11,638,687,000	9,935,036,000
Repurchase Agreement Borrowings \| Agency Mortgage Backed Securities
Collateral Positions
Assets Pledged	5,242,368,000	5,462,566,000
Repurchase Agreement Borrowings \| Cash
Collateral Positions
Assets Pledged	757,000	769,000
Repurchase Agreement Borrowings \| Legacy Non-Agency MBS
Collateral Positions
Assets Pledged	3,242,911,000	3,491,312,000
Non-Agency MBS acquired from consolidated VIEs	589,300,000	1,275,000,000
Non-Agency MBS pledged as collateral in connection with contemporaneous repurchase and reverse repurchase agreements entered into with a single counterparty	735,200,000	731,000,000
Repurchase Agreement Borrowings \| RPL/NPL MBS
Collateral Positions
Assets Pledged	2,317,938,000	160,688,000
Repurchase Agreement Borrowings \| U.S. Treasury securities
Collateral Positions
Assets Pledged	506,861,000	512,105,000
Repurchase Agreement Borrowings \| CRT securities
Collateral Positions
Assets Pledged	118,384,000	94,610,000
Repurchase Agreement Borrowings \| Residential whole loans
Collateral Positions
Assets Pledged	209,468,000	212,986,000
Reverse Repurchase Agreements:
Collateral Positions
Collateral Held	506,861,000	512,105,000
Reverse Repurchase Agreements: \| U.S. Treasury securities
Collateral Positions
Collateral Held	$ 506,861,000	$ 512,105,000

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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=34720971&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=35738203&loc=d3e5086-111524

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