Ellington Residential Mortgage REIT (EARN) 10-K 12 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 06, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	Ellington Residential Mortgage REIT
Entity Central Index Key	1560672
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		9,149,274
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$109,758,350

CONSOLIDATED_BALANCE_SHEET

CONSOLIDATED BALANCE SHEET (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS
Cash and cash equivalents	$45,237		$50,112
Mortgage-backed securities, at fair value	1,393,303		1,326,036
Due from brokers	18,531		18,347
Financial derivatives–assets, at fair value	3,072	[1]	34,963	[1]
Reverse repurchase agreements	13,987	[1]	0
Receivable for securities sold	41,834		76,692
Interest receivable	4,793		4,766
Other assets	317		174
Total Assets	1,521,074		1,511,090
LIABILITIES
Repurchase agreements	1,323,080	[1]	1,310,347	[1]
Payable for securities purchased	4,227		2,776
Due to brokers	583		22,788
Financial derivatives–liabilities, at fair value	8,700	[1]	1,069	[1]
U.S. Treasury securities sold short, at fair value	13,959		0
Dividend payable	5,032		4,570
Accrued expenses	890		996
Management fee payable	551		600
Interest payable	687		764
Total Liabilities	1,357,709		1,343,910
SHAREHOLDERS' EQUITY
Preferred shares, par value $0.01 per share, 100,000,000 shares authorized; (0 shares issued and outstanding, respectively)	0		0
Common shares, par value $0.01 per share, 500,000,000 shares authorized; (9,149,274 and 9,139,842 shares issued and outstanding, respectively)	91		91
Additional paid-in-capital	181,282		181,147
Accumulated deficit	-18,008		-14,058
Total Shareholders' Equity	163,365		167,180
Total Liabilities and Shareholders' Equity	$1,521,074		$1,511,090
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.

CONSOLIDATED_BALANCE_SHEET_Par

CONSOLIDATED BALANCE SHEET (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	9,149,274	9,139,842
Common stock, shares outstanding	9,149,274	9,139,842
Preferred stock, par value	$0.01	$0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

CONSOLIDATED_STATEMENT_OF_OPER

CONSOLIDATED STATEMENT OF OPERATIONS (USD $)	3 Months Ended	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
INTEREST INCOME (EXPENSE)
Interest income	$239	$46,824	$27,866
Interest expense	0	-4,511	-3,056
Total net interest income	239	42,313	24,810
EXPENSES
Management fees	124	2,285	2,066
Professional fees	125	986	624
Organizational Expenses	568	0	0
Other operating expenses	45	2,481	1,636
Total expenses	862	5,752	4,326
OTHER INCOME (LOSS)
Net realized gains (losses) on mortgage-backed securities	-19	2,457	-37,456
Net realized gains (losses) on financial derivatives	0	-31,878	7,310
Change in net unrealized gains (losses) on mortgage-backed securities	106	48,550	-26,146
Change in net unrealized gains (losses) on financial derivatives	0	-39,522	33,894
Total other income (loss)	87	-20,393	-22,398
NET INCOME (LOSS)	($536)	$16,168	($1,914)
NET INCOME (LOSS) PER COMMON SHARE:
Basic and Diluted (in dollars per share)	($0.33)	$1.77	($0.29)
CASH DIVIDENDS PER COMMON SHARE:
Dividends declared (in dollars per share)	$0	$2.20	$1.14

CONSOLIDATED_STATEMENT_OF_SHAR

CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (USD $)		Total	Common Shares [Member]	Preferred Stock [Member]	Additional Paid-in Capital [Member]	Receivable from Shareholders [Member]	Accumulated (Deficit) Earnings [Member]
Balance at Sep. 24, 2012		$0	$0	$0	$1,000	($1,000)	$0
Balance, in shares at Sep. 24, 2012			100	0
Issuance of shares, shares			1,575,000	0
Issuance of shares, Value		31,500,000	16,000	0	31,484,000
Stock Dividend, Shares	[1]		58,378	0
Stock Dividend, Value	[1]	0	0	0	1,190,000		-1,190,000
Repurchase of shares, Shares			-100	0
Repurchase of shares, Value		0	0	0	-1,000	1,000
Net income (loss)		-536,000					-536,000
Balance at Dec. 31, 2012		30,964,000	16,000	0	32,674,000	0	-1,726,000
Balance, in shares at Dec. 31, 2012			1,633,378	0
Issuance of shares, shares			7,500,000	0
Issuance of shares, Value		150,000,000	75,000	0	149,925,000
Issuance of restricted shares, shares			6,464	0
Issuance of restricted shares, value		0	0	0	0
Share based compensation		46,000			46,000
Offering costs		-1,498,000			-1,498,000
Dividends declared		-10,418,000					-10,418,000
Net income (loss)		-1,914,000					-1,914,000
Balance at Dec. 31, 2013		167,180,000	91,000	0	181,147,000	0	-14,058,000
Balance, in shares at Dec. 31, 2013			9,139,842	0
Issuance of restricted shares, shares			9,432	0
Issuance of restricted shares, value		0	0	0	0
Share based compensation		135,000			135,000
Dividends declared		-20,118,000					-20,118,000
Net income (loss)		16,168,000					16,168,000
Balance at Dec. 31, 2014		$163,365,000	$91,000	$0	$181,282,000	$0	($18,008,000)
Balance, in shares at Dec. 31, 2014			9,149,274	0
[1]	Stock dividend was declared on April 18, 2013 and was retrospectively applied.

CONSOLIDATED_STATEMENT_OF_CASH

CONSOLIDATED STATEMENT OF CASH FLOWS (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Cash flows provided by (used in) operating activities:
Net income (loss)	($536)	$16,168	($1,914)
Reconciliation of net income (loss) to net cash provided by (used in) operating activities:
Net realized (gains) losses on mortgage-backed securities	19	-2,457	37,456
Change in net unrealized (gains) losses on mortgage-backed securities	-106	-48,550	26,146
Net realized (gains) losses on financial derivatives	0	31,878	-7,310
Change in net unrealized (gains) losses on financial derivatives	0	39,522	-33,894
Amortization of premiums and accretion of discounts (net)	-114	7,174	3,911
Share based compensation	0	135	46
(Increase) decrease in assets:
Due from brokers	0	-184	-18,347
Interest receivable	-39	-27	-4,727
Other assets	0	-134	-174
Increase (decrease) in liabilities:
Due to brokers	0	-22,205	22,788
Accrued expenses	716	66	281
Interest payable	0	-77	764
Management fees payable	116	-49	484
Net cash provided by operating activities	56	21,260	25,510
Cash flows provided by (used in) investing activities:
Purchases of mortgage-backed securities	-13,643	-2,019,101	-2,889,912
Proceeds from sale of mortgage-backed securities	248	1,934,237	1,388,043
Principal repayments of mortgage-backed securities	0	98,144	47,994
Proceeds from investments sold short	0	211,937	2,043
Repurchase of investments sold short	0	-198,381	-2,036
Proceeds from disposition of financial derivatives	0	9,145	31,276
Purchase of financial derivatives	0	-41,024	-23,967
Payments made on reverse repurchase agreements	0	-1,094,706	-4,098
Proceeds from reverse repurchase agreements	0	1,080,719	4,098
Net cash used in investing activities	-13,395	-19,030	-1,446,559
Cash flows provided by (used in) financing activities:
Proceeds from issuance of common shares	31,500	0	150,000
Offering costs paid	0	-182	-1,498
Dividends paid	0	-19,656	-5,849
Borrowings under repurchase agreements	0	5,995,452	6,516,450
Repayments of repurchase agreements	0	-5,982,719	-5,206,103
Cash provided by (used in) financing activities	31,500	-7,105	1,453,000
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	18,161	-4,875	31,951
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	50,112	18,161
CASH AND CASH EQUIVALENTS, END OF PERIOD	18,161	45,237	50,112
Supplemental disclosure of cash flow information:
Interest paid	$0	$4,589	$2,292

Organization_and_Investment_Ob

Organization and Investment Objective	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Investment Objective	Organization and Investment Objective
	Ellington Residential Mortgage REIT, or "EARN," was formed as a Maryland real estate investment trust, or "REIT," on August 2, 2012, and commenced operations on September 25, 2012. EARN conducts its business through its wholly owned subsidiaries, EARN OP GP LLC, or the "General Partner," and Ellington Residential Mortgage LP, or the "Operating Partnership," which were formed as a Delaware limited liability company and a Delaware limited partnership, respectively, on July 31, 2012 and commenced operations on September 25, 2012. The Operating Partnership conducts its business of acquiring, investing in, and managing residential mortgage-related and real estate-related assets through its wholly owned subsidiaries. EARN, the General Partner, the Operating Partnership, and their consolidated subsidiaries are hereafter defined as the "Company."
	Ellington Residential Mortgage Management LLC, or the "Manager," serves as the Manager of the Company pursuant to the terms of a management agreement (the "Management Agreement"). The Manager is an affiliate of Ellington Management Group, L.L.C., or "EMG," an investment management firm that is registered as an investment adviser with a 20-year history of investing in a broad spectrum of mortgage-backed securities and related derivatives, with an emphasis on the residential mortgage-backed securities, or "RMBS," market. In accordance with the terms of the Management Agreement and the Services Agreement, as discussed in Note 10, the Manager is responsible for administering the Company's business activities and day-to-day operations, and performs certain services, subject to oversight by the Board of Trustees. See Notes 8 and 10 for further information on the Management Agreement.
	The Company was formed through an initial strategic venture among affiliates of EMG and the Blackstone Tactical Opportunity Funds, or the "Blackstone Funds." These initial investors made an aggregate investment of approximately $31.5 million on September 25, 2012. On May 1, 2013, the Company priced an initial public offering of its common shares, pursuant to which it sold 6,450,000 shares to the public at a price of $20.00 per share. Concurrent with the initial public offering, the Company completed a private placement of 1,050,000 common shares to its initial investors at a purchase price of $20.00 per share which generated gross proceeds of $21.0 million. Proceeds to the Company from the initial public offering and concurrent private placement, net of offering costs, were approximately $148.5 million.
	The Company acquires and manages Agency and non-Agency RMBS, including Agency pools and Agency collateralized mortgage obligations, or "CMOs," and non-Agency CMOs, both investment grade and non-investment grade. The Company may also acquire and manage mortgage servicing rights, residential mortgage loans, and other mortgage- and real estate-related assets. The Company may also invest in other instruments including, but not limited to, forward-settling To-Be-Announced Agency pass-through certificates, or "TBAs," interest rate swaps and swaptions, U.S. Treasury securities, Eurodollar and U.S. Treasury futures, other financial derivatives, and cash equivalents. The Company's targeted investments may range from unrated (first loss) securities to AAA senior securities.
	The Company made the election to be taxed as a REIT under the Internal Revenue Code of 1986, as amended, or "the Code" commencing with the Company's short taxable year ended December 31, 2013. As a REIT, the Company is required to distribute annually at least 90% of its taxable income. As long as the Company continues to qualify as a REIT, it will not be subject to U.S. federal or state corporate taxes on its taxable income to the extent that it distributes all of its annual taxable income to its shareholders. It is the intention of the Company to distribute at least 100% of its taxable income, after application of available tax attributes, within the limits prescribed by the Code, which may extend into the subsequent taxable year.

Significant_Accounting_Policie

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies
	(A) Basis of Presentation: The Company's consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America, or "U.S. GAAP." Entities in which the Company has a controlling financial interest, through ownership of the majority of the entities' voting equity interests, or through other contractual right that give the Company control, are consolidated by the Company. All inter-company balances and transactions have been eliminated. The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates and those differences could be material.
	(B) Valuation: The Company applies ASC 820-10, Fair Value Measurement and Disclosures ("ASC 820-10"), to its holdings of financial instruments. ASC 820-10 establishes a three-level valuation hierarchy for disclosure of fair value measurements. The valuation hierarchy is based upon the observability of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows:
	•	Level 1—inputs to the valuation methodology are observable and reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Currently, the types of financial instruments the Company generally includes in this category are, exchange-traded derivatives and cash and cash equivalents,
	•	Level 2—inputs to the valuation methodology other than quoted prices included in Level 1 are observable for the asset or liability, either directly or indirectly. Currently, the types of financial instruments that the Company generally includes in this category are Agency RMBS, non-Agency RMBS determined to have sufficiently observable market data, U.S. Treasury securities, actively traded derivatives such as TBAs, interest rate swaps, and swaptions, and
	•	Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement. Currently, this category includes RMBS where there is less price transparency.
	For certain financial instruments, the various inputs that management uses to measure fair value for such financial instrument may fall into different levels of the fair value hierarchy. In such cases, the determination of which category within the fair value hierarchy is appropriate for such financial instrument is based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the financial instrument. The Company may use valuation techniques consistent with the market and income approaches to measure the fair value of its assets and liabilities. The market approach uses third-party valuations and information obtained from market transactions involving identical or similar assets or liabilities. The income approach uses projections of the future economic benefits of an instrument to determine its fair value, such as in the discounted cash flow methodology. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risk associated with investing in these financial instruments. Transfers between levels of the fair value hierarchy are assumed to occur at the end of the reporting period.
	Summary Valuation Techniques
	For financial instruments that are traded in an "active market," the best measure of fair value is the quoted market price. However, many of the Company's financial instruments are not traded in an active market. Therefore, management generally uses third-party valuations when available. If third-party valuations are not available, management uses other valuation techniques, such as the discounted cash flow methodology. The following are summary descriptions, for the various categories of financial instruments, of the valuation methodologies management uses in determining fair value of the Company's financial instruments in such categories. Management utilizes such methodologies to assign a good faith fair value (the estimated price that, in an orderly transaction at the valuation date, would be received to sell an asset, or paid to transfer a liability, as the case may be) to each such financial instrument.
	Valuations for fixed rate RMBS pass-throughs issued by a U.S government agency or government-sponsored enterprise, or "GSE," are typically based on observable pay-up data (pay-ups are price premiums for specified categories of fixed rate pools relative to their TBA counterparts) or models that use observable market data, such as interest rates and historical prepayment speeds, and are validated against third-party valuations. With respect to the Company's other RMBS investments and TBAs, management seeks to obtain at least one third-party valuation, and often obtains multiple valuations when available. Management has been able to obtain third-party valuations on the vast majority of these instruments and expects to continue to solicit third-party valuations in the future. Management generally values each financial instrument at the average of third-party valuations received and not rejected as described below. Third-party valuations are not binding, and while management generally does not adjust the valuations it receives, management may challenge or reject a valuation when, based on its validation criteria, management determines that such valuation is unreasonable or erroneous. Furthermore, based on its validation criteria management may determine that the average of the third-party valuations received for a given instrument does not result in what management believes to be the fair value of such instrument, and in such circumstances management may override this average with its own good faith valuation. The validation criteria may take into account output from management's own models, recent trading activity in the same or similar instruments, and valuations received from third parties. The use of proprietary models requires the use of a significant amount of judgment and the application of various assumptions including, but not limited to, assumptions concerning future prepayment rates and default rates.
	Given their relatively high level of price transparency, Agency RMBS pass-throughs and TBAs are typically designated as Level 2 assets, although Agency interest only and inverse interest only RMBS are currently designated as Level 3 assets since they generally have less price transparency. Non-Agency RMBS are generally classified as either Level 2 or Level 3 based on analysis of available market data such as recent trades, executable bids, and reported "market color." Furthermore, the methodology used by the third-party valuation providers is reviewed at least annually by management, so as to ascertain whether such providers are utilizing observable market data to determine the valuations that they provide.
	Interest rate swaps and swaptions are typically valued based on internal models that use observable market data, including applicable interest rates in effect as of the measurement date; the model-generated valuations are then typically compared to counterparty valuations for reasonableness. These financial derivatives are generally designated as Level 2 instruments.
	The Company's repurchase and reverse repurchase agreements are carried at cost, which approximates fair value. Repurchase agreements and reverse repurchase agreements are classified as Level 2 assets and liabilities based on the adequacy of the collateral and their short term nature.
	The Company's valuation process, including the application of validation criteria, is overseen by the Manager's Valuation Committee. The Valuation Committee includes senior level executives from various departments within the Manager, and each quarter the Valuation Committee reviews and approves the valuations of the Company's investments. The valuation process also includes a monthly review by the Company's third party administrator. The goal of this review is to replicate various aspects of the Company's valuation process based on the Company's documented procedures.
	Because of the inherent uncertainty of valuation, the estimated fair value of the Company's financial instruments may differ significantly from the values that would have been used had a ready market for the financial instruments existed, and the differences could be material to the consolidated financial statements.
	(C) Accounting for Mortgage-Backed Securities: Purchases and sales of investments are recorded on trade date and realized and unrealized gains and losses are calculated based on identified cost.
	The Company has chosen to make a fair value election pursuant to ASC 825-10, Financial Instruments, for its mortgage-backed securities portfolio. Electing the fair value option allows the Company to record changes in fair value in the Consolidated Statement of Operations, which, in management's view, more appropriately reflects the results of operations for a particular reporting period as all securities activities will be recorded in a similar manner. As such, mortgage-backed securities are recorded at fair value on the Consolidated Balance Sheet and the period change in fair value is recorded in current period earnings on the Consolidated Statement of Operations as a component of Change in net unrealized gains (losses) on mortgage-backed securities.
	(D) Interest Income: Coupon interest income on investment securities is accrued based on the outstanding principal balance and the current coupon rate on each security. The Company amortizes premiums and accretes discounts on its fixed income securities. For RMBS that are deemed to be of high credit quality at the time of purchase, premiums and discounts are generally amortized into interest income over the life of such securities using the effective interest method. For securities subject to prepayment risk, an effective yield retroactive to the time of purchase is periodically recomputed based on actual prepayments and changes in projected prepayment activity, and a catch-up adjustment is made to amortization to reflect the cumulative impact of the change in effective yield. For RMBS that are deemed not to be of high credit quality at the time of purchase, interest income is recognized based on the effective interest method. For purposes of determining the effective interest rate, management estimates the future expected cash flows of its investment holdings based on assumptions including, but not limited to, assumptions for future prepayment rates, default rates, and loss severities (each of which may in turn incorporate various macro-economic assumptions, such as future housing prices). These assumptions are re-evaluated not less than quarterly. Principal write-offs are generally treated as realized losses. Changes in projected cash flows, as applied to the current amortized cost of the security, may result in a prospective change in the yield/interest income recognized on such securities.
	The Company's accretion of discounts and amortization of premiums on securities for U.S. federal and other tax purposes is likely to differ from the accounting treatment under U.S. GAAP of these items as described above.
	(E) Cash and Cash Equivalents: Cash and cash equivalents include cash and short term investments with original maturities of three months or less at the date of acquisition. Cash equivalents are recorded at cost plus accrued interest, which approximates fair value. Cash and cash equivalents typically include amounts held in an interest bearing overnight account and amounts held in money market funds, and these balances generally exceed insured limits.
	(F) Due from brokers/Due to brokers: Due from brokers and Due to brokers accounts on the Consolidated Balance Sheet include collateral transferred to or received from counterparties, including clearinghouses, along with receivables and payables for open and/or closed derivative positions.
	(G) Financial Derivatives: The Company may enter into various types of financial derivatives subject to its investment guidelines, which include restrictions associated with maintaining qualification as a REIT. The Company's financial derivatives are predominantly subject to bilateral collateral arrangements or clearing in accordance with the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010. The Company may be required to deliver or may receive cash or securities as collateral upon entering into derivative transactions. In addition, changes in the relative value of financial derivative transactions may require the Company or the counterparty to post or receive additional collateral. In the case of cleared financial derivatives, the clearinghouse becomes the Company's counterparty and a futures commission merchant acts as intermediary between the Company and the clearinghouse with respect to all facets of the related transaction, including the posting and receipt of required collateral. Collateral received by the Company is reflected on the Consolidated Balance Sheet as "Due to Brokers." Conversely, collateral posted by the Company is reflected as "Due from Brokers" on the Consolidated Balance Sheet. The types of financial derivatives that have been utilized by the Company to date are interest rate swaps, TBAs, swaptions, and futures.
	Swaps: The Company has entered into interest rate swaps, which are contractual agreements whereby one party pays a floating interest rate on a notional principal amount and receives a fixed rate payment on the same notional principal, or vice versa, for a fixed period of time.
	Swaps change in value with movements in interest rates or total return of the reference securities. During the term of swap contracts, changes in value are recognized as unrealized gains or losses on the Consolidated Statement of Operations. When a contract is terminated, the Company realizes a gain or loss equal to the difference between the proceeds from (or cost of) the closing transaction and the Company's basis in the contract, if any. Periodic payments or receipts required by swap agreements are recorded as unrealized gains or losses when accrued and realized gains or losses when received or paid. Upfront payments paid and/or received by the Company to open swap contracts are recorded as an asset and/or liability on the Consolidated Balance Sheet and are recorded as a realized gain or loss on the termination date.
	TBA Securities: The Company has transacted in the forward settling TBA market. A TBA position is a forward contract for the purchase ("long position") or sale ("short position") of Agency RMBS at a predetermined price, face amount, issuer, coupon, and maturity on an agreed-upon future delivery date. For each TBA contract and delivery month, a uniform settlement date for all market participants is determined by the Securities Industry and Financial Markets Association. The specific Agency RMBS to be delivered into the contract at the settlement date are not known at the time of the transaction. The Company typically does not take delivery of TBAs, but rather enters into offsetting transactions and settles the associated receivable and payable balances with its counterparties. The Company primarily uses TBAs to mitigate interest rate risk, but from time to time it also holds net long positions in certain TBA securities as a means of acquiring exposure to Agency RMBS.
	TBAs are accounted for by the Company as financial derivatives. The difference between the contract price and the fair value of the TBA position as of the reporting date is included in Change in net unrealized gains (losses) on financial derivatives, in the Consolidated Statement of Operations. Upon settlement of the TBA contract, the realized gain (loss) on the TBA contract is equal to the net cash amount received (paid).
	Options: The Company has entered into swaption contracts. It may purchase or write put, call, straddle, or other similar options contracts. The Company enters into options contracts primarily to help mitigate interest rate risk. When the Company purchases an options contract, the option asset is initially recorded at an amount equal to the premium paid, if any, and is subsequently marked-to-market. Premiums paid for purchasing options contracts that expire unexercised are recognized on the expiration date as realized losses. If an options contract is exercised, the premium paid is subtracted from the proceeds of the sale or added to the cost of the purchase to determine whether the Company has realized a gain or loss on the related investment transaction. When the Company writes an options contract, the option liability is initially recorded at an amount equal to the premium received, if any, and is subsequently marked-to-market. Premiums received for writing options contracts that expire unexercised are recognized on the expiration date as realized gains. If an options contract is exercised, the premium received is subtracted from the cost of the purchase or added to the proceeds of the sale to determine whether the Company has realized a gain or loss on the related investment transaction. When the Company enters into a closing transaction, the Company will realize a gain or loss depending upon whether the amount from the closing transaction is greater or less than the premiums paid or received. In general, the Company's options contracts contain forward-settling premiums. In this case, no money is exchanged upfront; instead, the agreed-upon premium is paid by the buyer upon expiration of the options contract, regardless of whether or not the options contract is exercised.
	Futures Contracts: A futures contract is an exchange-traded agreement to buy or sell an asset for a set price on a future date. Initial margin deposits are made upon entering into futures contracts and can be either in the form of cash or securities. During the period the futures contract is open, changes in the value of the contract are recognized as unrealized gains or losses by marking-to-market to reflect the current market value of the contract. Variation margin payments are made or received periodically, depending upon whether unrealized losses or gains are incurred. When the contract is closed, the Company records a realized gain or loss equal to the difference between the proceeds of the closing transaction and the Company's basis in the contract.
	Financial derivative assets are included in Financial derivatives–assets, at fair value on the Consolidated Balance Sheet while financial derivative liabilities are included in Financial derivatives–liabilities, at fair value on the Consolidated Balance Sheet.
	(H) Repurchase Agreements and Reverse Repurchase Agreements: The Company enters into repurchase agreements with third-party broker-dealers, whereby it sells securities under agreements to repurchase at an agreed upon price and date. The Company also enters into reverse repurchase agreement transactions with third-party broker-dealers, whereby it purchases securities under agreements to resell at an agreed upon price and date. The Company accounts for repurchase agreements as collateralized borrowings, with the initial sale price representing the amount borrowed, and with the future repurchase price consisting of the amount borrowed plus interest, at the implied interest rate of the repurchase agreement, on the amount borrowed over the term of the repurchase agreement. The interest rate on a repurchase agreement or a reverse repurchase agreement is based on competitive market rates (or competitive market spreads, in the case of agreements with floating interest rates) at the time such agreement is entered into. When the Company enters into a repurchase agreement, the lender establishes and maintains an account containing cash and/or securities having a value not less than the repurchase price, including accrued interest, of the repurchase agreement. Repurchase and reverse repurchase agreements that are conducted with the same counterparty can be reported on a net basis if they meet the requirements under the authoritative guidance. Repurchase agreements and reverse repurchase agreements are carried at their contractual amounts, which approximate fair value.
	(I) U.S. Treasury Securities: The Company may purchase or sell short U.S. Treasury securities to help mitigate the potential impact of changes in interest rates on the performance of its portfolio. The Company may borrow securities under reverse repurchase agreements to enable it to deliver U.S. Treasury securities that it has sold short.
	(J) Organizational Expenses: Organizational expenses are expensed as incurred. Organizational expenses incurred by the Company consisted mainly of legal fees.
	(K) Offering Costs/Deferred Offering Costs: Offering costs are charged against shareholders' equity and typically include legal, accounting, printing, and other fees associated with the cost of raising equity capital.
	(L) Share Based Compensation: The Company applies the provisions of ASC 718, Compensation—Shares Compensation ("ASC 718"), with regard to its equity incentive plans. ASC 718 covers a wide range of share-based compensation arrangements including share options, restricted share plans, performance-based awards, share appreciation rights, and employee share purchase plans. ASC 718 requires that compensation cost relating to share-based payment transactions be recognized in financial statements. The cost is measured based on the fair value of the equity or liability instruments issued.
	(M) Dividends: Dividends payable are recorded on the declaration date.
	(N) Earnings Per Share: In accordance with the provisions of ASC 260, Earnings per Share, the Company calculates basic income (loss) per share by dividing net income (loss) for the period by the weighted average of the Company's common shares outstanding for that period. Diluted income (loss) per share takes into account the effect of dilutive instruments, such as share options and warrants, and uses the average share price for the period in determining the number of incremental shares that are to be added to the weighted average number of shares outstanding.
	(O) Share Repurchases: Common shares that are repurchased by the Company subsequent to issuance decrease the total number of shares issued and outstanding.
	(P) Income Taxes: Prior to May 1, 2013, the Company, as a business trust with more than one owner, was considered a partnership for U.S. federal income tax purposes. In general, partnerships are not subject to entity-level tax on their income, but the income of a partnership is taxable to its owners on a flow-through basis. For the periods September 25, 2012 (commencement of operations) through December 31, 2012 and January 1, 2013 through April 30, 2013, the Company filed its tax return as a partnership. Effective May 1, 2013, the Company made the election to be taxed as a corporation. In addition, the Company elected to be taxed as a REIT under Sections 856 to 860 of the Code commencing with the short taxable period May 1, 2013 through December 31, 2013. As a REIT, the Company is generally not subject to corporate-level federal and state income tax on net income it distributes to its stockholders. To qualify as a REIT, the Company must meet a number of organizational and operational requirements, including the distribution of at least 90% of its annual taxable income to shareholders. Even if the Company qualifies as a REIT, it may be subject to certain federal, state, local and foreign taxes on its income and property and to federal income and excise taxes on its undistributed taxable income.
	The Company follows the authoritative guidance on accounting for and disclosure of uncertainty on tax positions, which requires management to determine whether a tax position of the company is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals of the litigation process, based on the technical merits of the position. For uncertain tax positions, the tax benefit to be recognized is measured as the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company did not have any unrecognized tax benefits at December 31, 2014. In the normal course of business, the Company may be subject to examination by federal, state, local, and foreign jurisdictions, where applicable, for the current period, 2013, and 2012 (its open tax years). The Company may take positions with respect to certain tax issues which depend on legal interpretation of facts or applicable tax regulations. Should the relevant tax regulators successfully challenge any of such positions, the Company might be found to have a tax liability that has not been recorded in the accompanying consolidated financial statements. Also, management's conclusions regarding the authoritative guidance may be subject to review and adjustment at a later date based on changing tax laws, regulations, and interpretations thereof. There were no amounts accrued for penalties or interest as of or during the periods presented in these consolidated financial statements.
	(Q) Recent Accounting Pronouncements: Under the Jumpstart Our Business Startups Act, or the "JOBS Act," the Company meets the definition of an "emerging growth company." The Company has elected to follow the extended transition period for complying with new or revised U.S. accounting standards pursuant to Section 107(b) of the JOBS Act. As a result, the Company will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-public entities.
	In June 2014, the FASB issued ASU No. 2014-11, Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures ("ASU 2014-11"). This amends ASC 860, Transfers and Servicing ("ASC 860"), to require disclosure of repurchase-to-maturity transactions to be accounted for as secured borrowings rather than sales of an asset, and transfers of financial assets with a contemporaneous repo will no longer be evaluated to determine whether they should be accounted for on a combined basis as forward contracts. The new guidance also prescribes additional disclosures particularly on the nature of collateral pledged under repurchase agreements accounted for as secured borrowings. ASU 2014-11 is effective for annual periods beginning after December 15, 2014 and interim periods beginning after December 31, 2015. The adoption of ASC 860, as amended by ASU 2014-11 is not expected to have a material impact on the Company's consolidated financial statements.
	In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern ("ASU 2014-15"). ASU 2014-15 requires management to perform interim and annual assessments of an entity's ability to continue as a going concern and to provide disclosure if events or conditions arise that would place substantial doubt on the entity's ability to continue as a going concern. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and subsequent interim and annual periods with early adoption permitted. The adoption of ASU 2014-15 is not expected to have a material impact on the Company's consolidated financial statements.
	In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis ("ASU 2015-02"). This amends ASC 810, Consolidation (ASC "810"), to improve targeted areas of consolidation guidance by simplifying the requirements of consolidation and placing more emphasis on risk of loss when determining a controlling financial interest. ASU 2015-02 is effective for the annual period ending after December 15, 2015, and subsequent interim and annual periods with early adoption permitted. The adoption of ASU 2015-02 is not expected to have a material impact on the Company's consolidated financial statements.

MortgageBacked_Securities

Mortgage-Backed Securities	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Mortgage-Backed Securities	Mortgage-Backed Securities
	The following tables present details of the Company's mortgage-backed securities portfolio at December 31, 2014 and December 31, 2013, respectively. The Company's Agency RMBS include mortgage pass-through certificates and CMOs representing interests in or obligations backed by pools of residential mortgage loans issued or guaranteed by a U.S. government agency or GSE. The non-Agency RMBS portfolio is not issued or guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, or any agency of the U.S. Government and is therefore subject to greater credit risk.
	By RMBS Type –
	December 31, 2014:
	($ in thousands)											Gross Unrealized											Weighted Average
		Current Principal			Unamortized Premium (Discount)				Amortized			Gains			Losses				Fair Value				Coupon		Yield		Weighted Average Life(Years)(1)
									Cost
	Agency RMBS:
	15-year fixed rate mortgages	$	130,720		$	6,304			$	137,024		$	1,113		$	(109	)		$	138,028			3.40%		2.46%		5.43
	20-year fixed rate mortgages	9,764			577				10,341			227			—				10,568				4.00%		3.04%		6.92
	30-year fixed rate mortgages	1,042,550			61,089				1,103,639			20,379			(1,764		)		1,122,254				4.09%		3.29%		8.48
	Adjustable rate mortgages	41,710			2,813				44,523			90			(330		)		44,283				4.60%		3.08%		5.97
	Reverse mortgages	31,412			2,741				34,153			300			(28		)		34,425				4.91%		2.56%		4.74
	Interest only securities	n/a			n/a				10,780			1,190			(726		)		11,244				4.04%		11.82%		2.68
	Total Agency RMBS	1,256,156			73,524				1,340,460			23,299			(2,957		)		1,360,802				4.05%		3.24%		7.54
	Non-Agency RMBS	50,668			(20,377		)		30,291			2,896			(686		)		32,501				2.29%		10.76%		4.97
	Total RMBS	$	1,306,824		$	53,147			$	1,370,751		$	26,195		$	(3,643	)		$	1,393,303			3.99%		3.41%		7.45
	-1	Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal.
	For the year ended December 31, 2014, the weighted average holdings of RMBS investments based on amortized cost was $1.363 billion.
	December 31, 2013:
	($ in thousands)											Gross Unrealized											Weighted Average
		Current Principal			Unamortized Premium (Discount)				Amortized			Gains			Losses				Fair Value				Coupon		Yield		Weighted Average Life(Years)(1)
									Cost
	Agency RMBS:
	15-year fixed rate mortgages	$	179,906		$	7,153			$	187,059		$	65		$	(3,252	)		$	183,872			3.09%		2.52%		5.76
	30-year fixed rate mortgages	1,029,629			41,565				1,071,194			490			(28,111		)		1,043,573				3.79%		3.30%		9.8
	Adjustable rate mortgages	43,525			2,647				46,172			46			(103		)		46,115				4.72%		3.24%		3.79
	Reverse mortgages	7,581			673				8,254			16			(2		)		8,268				4.85%		2.90%		3.41
	Interest only securities	n/a			n/a				10,718			2,841			(32		)		13,527				3.97%		11.79%		5.02
	Total Agency RMBS	1,260,641			52,038				1,323,397			3,458			(31,500		)		1,295,355				3.75%		3.26%		8.67
	Non-Agency RMBS	50,006			(21,327		)		28,679			2,196			(194		)		30,681				2.84%		9.12%		5.54
	Total RMBS	$	1,310,647		$	30,711			$	1,352,076		$	5,654		$	(31,694	)		$	1,326,036			3.72%		3.38%		8.56
	-1	Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal.
	For the year ended December 31, 2013, the weighted average holdings of RMBS investments based on amortized cost was $879.9 million.
	By Estimated Weighted Average Life
	As of December 31, 2014:
	($ in thousands)		Agency RMBS									Agency Interest Only Securities										Non-Agency RMBS
	Estimated Weighted Average Life		Fair			Amortized Cost				Weighted Average Coupon		Fair Value			Amortized Cost				Weighted Average Coupon			Fair Value				Amortized Cost				Weighted Average Coupon
			Value
	Less than three years		$	18,428		$	18,418			5.13	%	$	5,197		$	5,563			3.42	%		$	2,837			$	1,785			3.02	%
	Greater than three years and less than seven years		410,759			405,739				4.12	%	6,047			5,217				5.19	%		17,660				17,662				2.63	%
	Greater than seven years and less than eleven years		920,371			905,523				4	%	—			—				—	%		12,004				10,844				1.28	%
	Total		$	1,349,558		$	1,329,680			4.05	%	$	11,244		$	10,780			4.04	%		$	32,501			$	30,291			2.29	%
	As of December 31, 2013:
	($ in thousands)		Agency RMBS									Agency Interest Only Securities										Non-Agency RMBS
	Estimated Weighted Average Life		Fair			Amortized Cost				Weighted Average Coupon		Fair Value			Amortized Cost				Weighted Average Coupon			Fair Value				Amortized Cost				Weighted Average Coupon
			Value
	Less than three years		$	5,554		$	5,518			5.68	%	$	955		$	762			6.48	%		$	1,715			$	1,216			2.38	%
	Greater than three years and less than seven years		243,120			246,342				3.48	%	7,643			6,198				3.31	%		16,488				15,950				3.42	%
	Greater than seven years and less than eleven years		1,031,552			1,059,223				3.79	%	4,929			3,758				4.91	%		11,656				10,708				1.43	%
	Greater than eleven years		1,602			1,596				4.5	%	—			—				—	%		822				805				7.69	%
	Total		$	1,281,828		$	1,312,679			3.73	%	$	13,527		$	10,718			3.97	%		$	30,681			$	28,679			2.84	%
	The following table illustrates components of interest income on the Company's RMBS for the years ended December 31, 2014 and 2013 and September 25, 2012 (commencement of operations) to December 31, 2012:
			Year Ended										Year Ended											25-Sep-12
			31-Dec-14										31-Dec-13											(commencement of operations) to
																								31-Dec-12
	($ in thousands)		Coupon Interest			Net Amortization				Interest			Coupon Interest			Net Amortization				Interest				Coupon Interest				Net Amortization				Interest
										Income										Income												Income
	Agency RMBS		$	52,755		$	(9,112	)		$	43,643		$	30,504		$	(4,863	)		$	25,641			$	—			$	—			$	—
	Non-Agency RMBS		1,237			1,930				3,167			1,185			952				2,137				125				114				239
	Total		$	53,992		$	(7,182	)		$	46,810		$	31,689		$	(3,911	)		$	27,778			$	125			$	114			$	239

Valuation

Valuation	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Valuation	Valuation
	The following tables present the Company's financial instruments measured at fair value on:
	December 31, 2014:
	(In thousands)
	Description		Level 1			Level 2			Level 3			Total
	Assets:
	Mortgage-backed securities, at fair value:
	Agency RMBS:
	15-year fixed rate mortgages		$	—		$	138,028		$	—		$	138,028
	20-year fixed rate mortgages		—			10,568			—			10,568
	30-year fixed rate mortgages		—			1,122,254			—			1,122,254
	Adjustable rate mortgages		—			44,283			—			44,283
	Reverse mortgages		—			34,425			—			34,425
	Interest only securities		—			—			11,244			11,244
	Non-Agency RMBS		—			22,419			10,082			32,501
	Mortgage-backed securities, at fair value		—			1,371,977			21,326			1,393,303
	Financial derivatives–assets, at fair value:
	TBAs		—			476			—			476
	Fixed payer interest rate swaps		—			2,518			—			2,518
	Fixed payer swaptions		—			78			—			78
	Total financial derivatives–assets, at fair value		—			3,072			—			3,072
	Reverse repurchase agreements		—			13,987			—			13,987
	Total mortgage-backed securities, financial derivatives–assets, and reverse repurchase agreements, at fair value		$	—		$	1,389,036		$	21,326		$	1,410,362
	Liabilities:
	U.S. Treasury securities sold short, at fair value		$	—		$	(13,959	)	$	—		$	(13,959	)
	Financial derivatives–liabilities, at fair value:
	TBAs		—			(1,674		)	—			(1,674		)
	Fixed payer interest rate swaps		—			(7,026		)	—			(7,026		)
	Total financial derivatives–liabilities, at fair value		$	—		$	(8,700	)	$	—		$	(8,700	)
	Total U.S. Treasury securities and financial derivatives–liabilities, at fair value		$	—		$	(22,659	)	$	—		$	(22,659	)
	There were no transfers of financial instruments between Levels 1 and 2 of the fair value hierarchy during the year ended December 31, 2014.
	December 31, 2013:
	(In thousands)
	Description		Level 1			Level 2			Level 3			Total
	Assets:
	Mortgage-backed securities, at fair value:
	Agency RMBS:
	15-year fixed rate mortgages		$	—		$	183,872		$	—		$	183,872
	30-year fixed rate mortgages		—			1,043,573			—			1,043,573
	Adjustable rate mortgages		—			46,115			—			46,115
	Reverse mortgages		—			8,268			—			8,268
	Interest only securities		—			—			13,527			13,527
	Non-Agency RMBS		—			—			30,681			30,681
	Mortgage-backed securities, at fair value		—			1,281,828			44,208			1,326,036
	Financial derivatives–assets, at fair value:
	TBAs		—			2,263			—			2,263
	Fixed payer interest rate swaps		—			32,700			—			32,700
	Total financial derivatives–assets, at fair value		—			34,963			—			34,963
	Total mortgage-backed securities and financial derivatives–assets, at fair value		$	—		$	1,316,791		$	44,208		$	1,360,999
	Liabilities:
	Financial derivatives–liabilities, at fair value:
	TBAs		$	—		$	(28	)	$	—		$	(28	)
	Fixed payer interest rate swaps		—			(956		)	—			(956		)
	Fixed payer swaptions		—			(85		)	—			(85		)
	Total financial derivatives–liabilities, at fair value		$	—		$	(1,069	)	$	—		$	(1,069	)
	There were no transfers of financial instruments between Levels 1, 2, or 3 of the fair value hierarchy during the year ended December 31, 2013.
	The following tables present additional information about the Company's investments which are measured at fair value for which the Company has utilized Level 3 inputs to determine fair value:
	Year ended December 31, 2014:
	(In thousands)	Non-Agency RMBS			Agency RMBS
	Beginning balance as of December 31, 2013	$	30,681		$	13,527
	Purchases	14,712			4,853
	Proceeds from sales	(11,104		)	(2,330		)
	Principal repayments	(5,443		)	—
	(Amortization)/accretion, net	1,930			(3,136		)
Net realized gains	1,518			676
Change in net unrealized gains (losses)	207			(2,346		)
Transfers:
Transfers into level 3	—			—
Transfers out of level 3	(22,419		)	—
Ending balance as of December 31, 2014	$	10,082		$	11,244
All amounts of net realized and changes in net unrealized gains (losses) in the table above are reflected in the accompanying Consolidated Statement of Operations. The table above incorporates changes in net unrealized gains (losses) for both Level 3 financial instruments held by the Company at December 31, 2014, as well as Level 3 financial instruments disposed of by the Company during the year ended December 31, 2014. For Level 3 financial instruments held by the Company at December 31, 2014, change in net unrealized gains (losses) of $0.7 million and $(2.0) million, for the year ended December 31, 2014 relate to non-Agency RMBS and Agency RMBS, respectively.
At December 31, 2014, the Company transferred $22.4 million of non-Agency RMBS from Level 3 to Level 2. The decision to transfer these assets from Level 3 to Level 2 was based on observed market developments, including an increased volume of buying and selling of these and similar assets, greater consensus among market participants on price based on market quotes, and generally tighter credit spreads driven by improved performance in the underlying collateral as well as increased demand from investors seeking higher yielding assets. These factors have led to greater price transparency for these assets, thereby making a Level 2 designation appropriate in the Company's view. However, changes in observed market developments could impact future price transparency, and thereby cause a change in the level designation in subsequent periods.
Year ended December 31, 2013:
(In thousands)	Non-Agency RMBS			Agency RMBS
Beginning balance as of December 31, 2012	$	13,596		$	—
Purchases	41,734			12,167
Proceeds from sales	(23,007		)	—
Principal repayments	(5,923		)	—
(Amortization)/accretion, net	952			(1,449		)
Net realized gains	1,433			—
Change in net unrealized gains (losses)	1,896			2,809
Transfers:
Transfers into level 3	—			—
Transfers out of level 3	—			—
Ending balance as of December 31, 2013	$	30,681		$	13,527
All amounts of net realized and changes in net unrealized gains (losses) in the table above are reflected in the accompanying Consolidated Statement of Operations. The table above incorporates changes in net unrealized gains (losses) for both Level 3 financial instruments held by the Company at December 31, 2013, as well as Level 3 financial instruments disposed of by the Company during the year ended December 31, 2013. For Level 3 financial instruments held by the Company at December 31, 2013, change in net unrealized gains (losses) of $2.0 million and $2.8 million, for the year ended December 31, 2013 relate to non-Agency RMBS and Agency RMBS, respectively.
September 25, 2012 (commencement of operations) to December 31, 2012:
(In thousands)	Non-Agency RMBS
Beginning balance as of September 25, 2012	$	—
Purchases	13,643
Proceeds from sales	(248		)
Principal repayments	—
(Amortization)/accretion, net	114
Net realized losses	(19		)
Change in net unrealized gains (losses)	106
Transfers:
Transfers into level 3	—
Transfers out of level 3	—
Ending balance as of December 31, 2012	$	13,596
All amounts of net realized and changes in net unrealized gains (losses) in the table above are reflected in the accompanying Consolidated Statement of Operations. The table above incorporates changes in net unrealized gains (losses) for both Level 3 financial instruments held by the Company at December 31, 2012, as well as Level 3 financial instruments disposed of by the Company during the period September 25, 2012 (commencement of operations) to December 31, 2012. For Level 3 financial instruments held by the Company at December 31, 2013, change in net unrealized gains (losses) of $0.1 million for the period September 25, 2012 (commencement of operations) to December 31, 2012 relate to non-Agency RMBS.
The following tables identify the significant unobservable inputs that affect the valuation of the Company's Level 3 assets and liabilities as of December 31, 2014 and December 31, 2013:
December 31, 2014:
								Range
Description		Fair Value			Valuation Technique		Significant	Min			Max			Weighted Average(1)
							Unobservable Input
		(In thousands)
Non-Agency RMBS		$	7,819		Market quotes		Non-Binding Third-Party Valuation	$	21.38		$	84.91		$	54.11
Non-Agency RMBS		2,263			Discounted Cash Flows		Yield	6.3		%	6.3		%	6.3		%
							Projected Collateral Prepayments	35.9		%	35.9		%	35.9		%
							Projected Collateral Losses	7.5		%	7.5		%	7.5		%
							Projected Collateral Recoveries	11		%	11		%	11		%
							Projected Collateral Scheduled Amortization	45.6		%	45.6		%	45.6		%
														100		%
Agency RMBS–Interest Only Securities		7,006			Market quotes		Non-Binding Third-Party Valuation	$	4.74		$	20.38		$	13.35
Agency RMBS–Interest Only Securities		4,238			Option Adjusted Spread ("OAS")		LIBOR OAS (2)	83			1,952			490
							Projected Collateral Prepayments	63.3		%	92.3		%	75.2		%
							Projected Collateral Scheduled Amortization	7.7		%	36.7		%	24.8		%
														100		%
-1	Averages are weighted based on the fair value of the related instrument.
-2	Shown in basis points.
December 31, 2013:
								Range
Description		Fair Value			Valuation Technique		Significant	Min			Max			Weighted Average(1)
							Unobservable Input
		(In thousands)
Non-Agency RMBS		$	27,422		Market quotes		Non-Binding Third-Party Valuation	$	20		$	100.25		$	75.39
Non-Agency RMBS		3,259			Discounted Cash Flows		Yield	6		%	17		%	11.9		%
							Projected Collateral Prepayments	12.2		%	58.1		%	33.9		%
							Projected Collateral Losses	6.4		%	26.5		%	11.8		%
							Projected Collateral Recoveries	4.6		%	12.8		%	8.8		%
							Projected Collateral Scheduled Amortization	29.9		%	54.9		%	45.5		%
														100		%
Agency RMBS–Interest Only Securities		12,368			Market quotes		Non-Binding Third-Party Valuation	$	4.99		$	22.47		$	14.92
Agency RMBS–Interest Only Securities		1,159			Option Adjusted Spread ("OAS")		LIBOR OAS(2)	436			436			436
							Projected Collateral Prepayments	57.8		%	57.8		%	57.8		%
							Projected Collateral Scheduled Amortization	42.2		%	42.2		%	42.2		%
														100		%
-1	Averages are weighted based on the fair value of the related instrument.
-2	Shown in basis points.
Third-party non-binding valuations are validated by comparing such valuations to internally generated prices based on the Company's models and to recent trading activity in the same or similar instruments. For those instruments valued using discounted cash flows, collateral prepayments, losses, recoveries, and scheduled amortization are projected over the remaining life of the collateral and expressed as a percentage of the collateral's current principal balance. For those assets valued using the LIBOR Option Adjusted Spread, or "OAS," valuation methodology, cash flows are projected using the Company's models over multiple interest rate scenarios, and these projected cash flows are then discounted using the LIBOR rates implied by each interest rate scenario. The LIBOR OAS of an asset is then computed as the unique constant yield spread that, when added to all LIBOR rates in each interest rate scenario generated by the model, will equate (a) the expected present value of the projected asset cash flows over all model scenarios to (b) the actual current market price of the asset. LIBOR OAS is therefore model-dependent. Generally speaking, LIBOR OAS measures the additional yield spread over LIBOR that an asset provides at its current market price after taking into account any interest rate options embedded in the asset.
Material changes in any of the inputs above in isolation could result in a significant change to reported fair value measurements. Fair value measurements are impacted by the interrelationships of these inputs. For example, a higher expectation of collateral prepayments will generally result in a lower expectation of collateral losses. Conversely, higher losses will generally result in lower prepayments.

Derivative_Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Financial Derivatives
	The Company is exposed to certain risks arising from both its business operations and economic conditions. Specifically, the Company's primary source of financing is repurchase agreements and the Company enters into financial derivative and other instruments to manage exposure to variable cash flows on portions of its borrowings under those repurchase agreements. Since the interest rates on repurchase agreements typically change with market interest rates such as LIBOR, the Company is exposed to constantly changing interest rates, which accordingly affects cash flows associated with these rates on its borrowings. To mitigate the effect of changes in these interest rates and their related cash flows, the Company may enter into a variety of derivative contracts, including interest rate swaps, swaptions, and TBAs. Additionally, from time to time, the Company may use short positions in U.S. Treasury securities to mitigate its interest rate risk.
	The following table details fair value of the Company's holdings of financial derivatives as of December 31, 2014 and December 31, 2013:
			31-Dec-14			31-Dec-13
			(In thousands)
	Financial derivatives–assets, at fair value:
	TBA securities purchase contracts		$	387		$	1
	TBA securities sale contracts		89			2,262
	Fixed payer interest rate swaps		2,518			32,700
	Swaptions		78			—
	Total financial derivatives–assets, at fair value:		3,072			34,963
	Financial derivatives–liabilities, at fair value:
	TBA securities purchase contracts		(5		)	—
	TBA securities sale contracts		(1,669		)	(28		)
	Fixed payer interest rate swaps		(7,026		)	(956		)
	Swaptions		—			(85		)
	Total financial derivatives–liabilities, at fair value:		(8,700		)	(1,069		)
	Total		$	(5,628	)	$	33,894
	Interest Rate Swaps
	The following tables provide information about the Company's interest rate swaps as of December 31, 2014 and December 31, 2013:
	December 31, 2014:
										Weighted Average
	Remaining Maturity		Notional Amount			Fair Value				Pay Rate			Receive Rate			Remaining Years to Maturity
			(In thousands)
	2016		$	48,000		$	(91	)		0.8	%		0.23	%		1.77
	2017		74,750			(388		)		1.21			0.24			2.59
	2018		10,000			167				0.84			0.23			3.33
	2020		23,500			471				1.42			0.23			5.38
	2023		209,350			140				2.13			0.23			8.4
	2024		12,900			(605		)		2.73			0.23			9.45
	2043		46,320			(4,202		)		3.12			0.23			28.42
	Total		$	424,820		$	(4,508	)		1.87	%		0.23	%		8.56
	December 31, 2013:
										Weighted Average
	Remaining Maturity		Notional Amount			Fair Value				Pay Rate			Receive Rate			Remaining Years to Maturity
			(In thousands)
	2016		$	48,000		$	(171	)		0.8	%		0.24	%		2.77
	2017		124,000			(517		)		1.19			0.24			3.61
	2018		156,500			2,784				1.19			0.24			4.63
	2020		137,100			6,444				1.49			0.24			6.06
	2023		218,000			14,599				2.16			0.24			9.41
	2043		64,750			8,605				3.18			0.24			29.44
	Total		$	748,350		$	31,744			1.67	%		0.24	%		8.14
	Interest Rate Swaptions
	The following tables provide information about the Company's swaptions as of December 31, 2014 and December 31, 2013.
	December 31, 2014:
	Option							Underlying Swap
	Type		Fair Value			Months to Expiration		Notional				Term (Years)
								Amount						Fixed Rate
	($ in thousands)
	Straddle		$	78		6.5		$	9,700			10		3.00%
	December 31, 2013:
	Option							Underlying Swap
	Type		Fair Value			Months to Expiration		Notional				Term (Years)		Fixed Rate
								Amount
	($ in thousands)
	Fixed Payer		$	(59	)	8.9		$	22,000			10		3.31%
	Straddle		$	(26	)	9.9		$	8,000			10		3.08%
	TBAs
	The Company uses TBAs primarily to mitigate interest rate risk, typically in the form of short positions. However, the Company may also invest in TBAs for speculative purposes, including holding long positions. Overall, the Company typically holds a net short position.
	The Company transacts in the forward settling To Be Announced MBS ("TBA") market. Pursuant to these TBA transactions, the Company agrees to purchase or sell, for future delivery, Agency RMBS with certain principal and interest terms and certain types of underlying collateral, but the particular Agency RMBS to be delivered is not identified until shortly before the TBA settlement date. TBAs are liquid and have quoted market prices and represent the most actively traded class of MBS. The Company primarily uses TBAs to mitigate interest rate risk, typically in the form of short positions. However, from time to time the Company also invests in TBAs as a means of acquiring additional exposure to Agency RMBS, or for speculative purposes, including holding long positions. Overall, the Company typically holds a net short position.
	The Company does not generally take delivery of TBAs; rather, it settles the associated receivable and payable with its trading counterparties on a net basis. Transactions with the same counterparty for the same TBA that result in a reduction of the position are treated as extinguished.
	As of December 31, 2014 and December 31, 2013, the Company had outstanding contracts to purchase ("long positions") and sell ("short positions") TBA securities as follows:
			31-Dec-14														31-Dec-13
TBA Securities		Notional Amount(1)			Cost				Market Value(3)				Net Carrying Value(4)			Notional Amount (1)			Cost			Market Value(3)			Net Carrying Value(4)
					Basis(2)														Basis(2)
(In thousands)
Purchase contracts:
Assets		$	53,319		$	54,757			$	55,144			$	387		$	1,600		$	1,725		$	1,726		$	1
Liabilities		15,000			15,603				15,598				(5		)	—			—			—			—
		68,319			70,360				70,742				382			1,600			1,725			1,726			1
Sale contracts:
Assets		(79,090		)	(85,730		)		(85,641		)		89			(363,078		)	(375,524		)	(373,262		)	2,262
Liabilities		(525,986		)	(559,219		)		(560,888		)		(1,669		)	(16,400		)	(17,518		)	(17,546		)	(28		)
		(605,076		)	(644,949		)		(646,529		)		(1,580		)	(379,478		)	(393,042		)	(390,808		)	2,234
Total TBA securities, net		$	(536,757	)	$	(574,589	)		$	(575,787	)		$	(1,198	)	$	(377,878	)	$	(391,317	)	$	(389,082	)	$	2,235
-1	Notional amount represents the principal balance of the underlying Agency RMBS.
-2	Cost basis represents the forward price to be paid for the underlying Agency RMBS.
-3	Market value represents the current market value of the underlying Agency RMBS (on a forward delivery basis) as of period end.
-4	Net carrying value represents the difference between the market value of the TBA contract as of period end and the cost basis and is reported in Financial derivatives-assets at fair value and Financial derivatives-liabilities at fair value on the Consolidated Balance Sheet.
The tables below detail the average notional values of the Company's financial derivatives, using absolute value of month end notional values, for the years ended December 31, 2014 and 2013:
Derivative Type		Year Ended December 31, 2014			Year Ended December 31, 2013
		(In thousands)
Interest rate swaps		$	566,379		$	609,310
TBAs		545,646			364,943
Interest rate swaptions		20,631			11,200
Gains and losses on the Company's financial derivatives for the years ended December 31, 2014 and 2013 are summarized in the tables below:
		Year Ended December 31, 2014
Derivative Type		Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps			Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps				Net Realized Gains (Losses) on Financial Derivatives				Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) on Financial Derivatives
(In thousands)
Fixed payer interest rate swaps		$	(9,217	)	$	1,823			$	(7,394	)		$	410		$	(36,662	)	$	(36,252	)
Swaptions					(935		)		(935		)					163			163
TBAs					(23,568		)		(23,568		)					(3,433		)	(3,433		)
Futures					19				19							—			—
Total		$	(9,217	)	$	(22,661	)		$	(31,878	)		$	410		$	(39,932	)	$	(39,522	)
		Year Ended December 31, 2013
Derivative Type		Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps			Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps				Net Realized Gains (Losses) on Financial Derivatives				Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) on Financial Derivatives
(In thousands)
Fixed payer interest rate swaps		$	(5,200	)	$	5,060			$	(140	)		$	(1,538	)	$	33,282		$	31,744
Swaptions					—				—							(85		)	(85		)
TBAs					7,450				7,450							2,235			2,235
Total		$	(5,200	)	$	12,510			$	7,310			$	(1,538	)	$	35,432		$	33,894
The Company did not have any derivatives outstanding during the period September 25, 2012 (commencement of operations) to December 31, 2012.
As of December 31, 2014, the Company also held short positions in U.S. Treasury securities, with a principal amount of $13.9 million and a fair value of $14.0 million.

Borrowings_under_Repurchase_Ag

Borrowings under Repurchase Agreements	12 Months Ended
	Dec. 31, 2014
Repurchase Agreements [Abstract]
Repurchase Agreements Disclosure [Text Block]	Borrowings under Repurchase Agreements
	The Company enters into repurchase agreements. A repurchase agreement involves the sale of an asset to a counterparty together with a simultaneous agreement to repurchase the transferred asset or similar asset from such counterparty at a future date. The Company accounts for its repurchase agreements as collateralized borrowings, with the transferred assets effectively serving as collateral for the related borrowing. The Company's repurchase agreements typically range in term from 30 to 180 days. The principal economic terms of each repurchase agreement—such as loan amount, interest rate, and maturity date—are typically negotiated on a transaction-by-transaction basis. Other terms and conditions, such as relating to events of default, are typically governed under the Company's master repurchase agreements, or "MRAs." Absent an event of default, the Company maintains beneficial ownership of the transferred securities during the term of the repurchase agreement and receives the related principal and interest payments. Interest rates on these borrowings are generally fixed based on prevailing rates corresponding to the terms of the borrowings, and interest is paid at the termination of the repurchase agreement at which time the Company may enter into a new repurchase agreement at prevailing market rates with the same counterparty, repay that counterparty and possibly negotiate financing terms with a different counterparty, or choose to no longer finance the related asset. In response to a decline in the fair value of the transferred securities, whether as a result of changes in market conditions, security paydowns, or other factors, repurchase agreement counterparties will typically make a margin call, whereby the Company will be required to post additional securities and/or cash as collateral with the counterparty in order to re-establish the agreed-upon collateralization requirements. In the event of increases in fair value of the transferred securities, the Company generally can require the counterparty to post collateral with it in the form of cash or securities. The Company is generally permitted to sell or re-pledge any securities posted by the counterparty as collateral; however, upon termination of the repurchase agreement the Company must return to the counterparty the same security that had been posted. The contractual amount (loan amount) of the Company's repurchase agreements approximates fair value, as the debt is short-term in nature.
	At any given time, the Company seeks to have its outstanding borrowings under repurchase agreements with several different counterparties in order to reduce the exposure to any single counterparty. As of December 31, 2014 and December 31, 2013, the Company had outstanding borrowings under repurchase agreements with ten and nine counterparties, respectively.
	The following table details the Company's outstanding borrowings under repurchase agreements as of December 31, 2014 and December 31, 2013:
		December 31, 2014					31-Dec-13
				Weighted Average					Weighted Average
	Remaining Days to Maturity	Borrowings Outstanding		Interest Rate		Remaining Days to Maturity	Borrowings Outstanding		Interest Rate		Remaining Days to Maturity
		(In thousands)
	30 days or less	$	437,633	0.33	%	15	$	338,700	0.35	%	14
	31-60 days	417,009		0.34		44	531,799		0.39		46
	61-90 days	333,580		0.36		72	326,386		0.38		72
	91-120 days	—		—		—	109,476		0.45		100
	121-150 days	—		—		—	3,986		0.56		136
	151-180 days	85,917		0.41		165	—		—		—
	301-330 days	48,941		0.47		317	—		—		—
	Total	$	1,323,080	0.35	%	60	$	1,310,347	0.38	%	49
	Repurchase agreements involving underlying investments that the Company sold prior to year end, for settlement following year end, are shown using their original maturity dates even though such repurchase agreements may be expected to be terminated early upon settlement of the sale of the underlying investment.
	As of both December 31, 2014 and December 31, 2013, the fair value of Agency RMBS transferred as collateral under outstanding borrowings under repurchase agreements was $1.4 billion. Collateral transferred under outstanding borrowings as of December 31, 2014 include Agency RMBS in the amount of $41.8 million that were sold prior to period end but for which such sale had not yet settled. Collateral transferred under outstanding borrowings as of December 31, 2013 include Agency RMBS in the amount of $76.1 million that were sold prior to period end but for which such sale had not yet settled. In addition the Company posted net cash collateral of $5.7 million and additional securities with a fair value of $2.1 million as of December 31, 2014 as a result of margin calls with various counterparties. The Company also held investments with an aggregate value of approximately $0.4 million, as of December 31, 2014, which were received to satisfy collateral requirements for various repurchase agreements. The Company posted additional net cash collateral of $14.8 million and additional securities with a fair value of $3.5 million as of December 31, 2013 as a result of margin calls with various counterparties. The Company also held investments with an aggregate value of approximately $0.5 million, as of December 31, 2013, which were received to satisfy collateral requirements for various repurchase agreements.

Offsetting_of_Assets_and_Liabi

Offsetting of Assets and Liabilities	12 Months Ended
	Dec. 31, 2014
Offsetting of Assets and Liabilities [Abstract]
OffsettingOfAssetsAndLiabilities [Text Block]	Offsetting of Assets and Liabilities
	The Company records financial instruments at fair value as described in Note 2. All financial instruments are recorded on a gross basis on the Consolidated Balance Sheet. In connection with its financial derivatives, repurchase agreements, and related trading agreements, the Company and its counterparties are required to pledge collateral. Cash or other collateral is exchanged as required with each of the Company's counterparties in connection with open derivative positions and repurchase agreements.
	The following tables present information about certain assets and liabilities representing financial instruments as of December 31, 2014 and December 31, 2013. The Company has not previously entered into master netting agreements with any of its counterparties. Certain of the Company's repurchase and reverse repurchase agreements and financial derivative transactions are governed by underlying agreements that generally provide a right of offset in the event of default or in the event of a bankruptcy of either party to the transaction.
	December 31, 2014:
	Description		Amount of Assets (Liabilities) Presented in the Consolidated Balance Sheet(1)			Financial Instruments Available for Offset			Financial Instruments Transferred or Pledged as Collateral(2)(3)		Cash Collateral (Received) Pledged(2)(3)			Net Amount
	(In thousands)
	Assets:
	Financial derivatives–assets		$	3,072		$	(2,722	)	$	—	$	—		$	350
	Reverse repurchase agreements		13,987			(13,987		)	—		—			—
	Liabilities:
	Financial derivatives–liabilities		(8,700		)	2,722			—		5,783			(195		)
	Repurchase agreements		(1,323,080		)	13,987			1,303,360		5,733			—
	-1	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
	-2	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore, the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2014 were $1.39 billion. As of December 31, 2014 total cash collateral on financial derivative assets and financial derivative liabilities excludes $0.5 million and $6.3 million of net excess cash collateral.
	-3	When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above table, the Company has made assumptions in allocating pledged or posted collateral among the various rows.
	December 31, 2013:
	Description		Amount of Assets (Liabilities) Presented in the Consolidated Balance Sheet(1)			Financial Instruments Available for Offset			Financial Instruments Transferred or Pledged as Collateral(2)(3)		Cash Collateral (Received) Pledged(2)(3)			Net Amount
	(In thousands)
	Assets:
	Financial derivatives–assets		$	34,963		$	(1,042	)	$	—	$	(22,360	)	$	11,561
	Liabilities:
	Financial derivatives–liabilities		(1,069		)	1,042			—		26			(1		)
	Repurchase agreements		(1,310,347		)	—			1,295,567		14,780			—
	-1	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
	-2	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2013 were $1.36 billion. As of December 31, 2013 total cash collateral on financial derivative assets and liabilities excludes $0.3 million and $3.1 million, respectively of net excess cash collateral.
	-3	When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above table, the Company has made assumptions in allocating pledged or posted collateral among the various rows.

Management_Fees

Management Fees	12 Months Ended
	Dec. 31, 2014
Management Fees Disclosure [Abstract]
Management Fees	Management Fees
	The Manager receives an annual management fee in an amount equal to 1.50% per annum of shareholders' equity (as defined in the Management Agreement) as of the end of each fiscal quarter (before deductions for any management fee with respect to such fiscal period). The management fee is payable quarterly in arrears. For the years ended December 31, 2014 and 2013 and September 25, 2012 (commencement of operations) to December 31, 2012, the total management fee incurred was approximately $2.3 million, $2.1 million, and $0.1 million, respectively.
	From inception through December 31, 2014, Shareholders' equity is defined in the Management Agreement, as of the end of any fiscal quarter, as (a) the sum of (1) the net proceeds from any issuances of common shares or other equity securities of the Company or the Operating Partnership (without double counting) since inception, plus (2) the Company's and the Operating Partnership's (without double counting) retained earnings or accumulated deficit calculated in accordance with U.S. GAAP at the end of the most recently completed fiscal quarter (without taking into account any non-cash equity compensation expense incurred in current or prior periods), less (b) any amount that the Company or the Operating Partnership has paid to repurchase common shares, limited partnership interests in the Operating Partnership or other equity securities since inception. Shareholders' equity excludes (1) any unrealized gains, losses, or non-cash equity compensation expenses that have impacted shareholders' equity as reported in the financial statements prepared in accordance with U.S. GAAP, regardless of whether such items are included in net income, and (2) one-time events pursuant to changes in U.S. GAAP, and certain non-cash items not otherwise described above, in each case, after discussions between the Manager and the Company's independent trustees and approval by a majority of the Company's independent trustees.
	Effective January 1, 2015 the Company entered into a Third Amended and Restated Management Agreement with the Manager, which replaces and supersedes the Second Amended and Restated Management Agreement. The Third Amended and Restated Management Agreement was adopted and executed for the primary purpose of redefining shareholders' equity. Shareholders' equity per the Second Amended and Restated Management Agreement had the definition as described above. Effective January 1, 2015, shareholders' equity is defined in the Third Amended and Restated Management Agreement, as of the end of any fiscal quarter, as (a) the sum of (1) the net proceeds from any issuances of common shares or other equity securities of the Company or the Operating Partnership (without double counting) since inception, plus (2) the Company's and the Operating Partnership's (without double counting) retained earnings or accumulated deficit calculated in accordance with U.S. GAAP at the end of the most recently completed fiscal quarter (without taking into account any non-cash equity compensation expense incurred in current or prior periods), less (b) any amount that the Company or the Operating Partnership has paid to repurchase common shares, limited partnership interests in the Operating Partnership or other equity securities since inception. Shareholders' equity excludes (1) non-cash equity compensation expenses that have impacted shareholders' equity as reported in the financial statements prepared in accordance with U.S. GAAP, and (2) one-time events pursuant to changes in U.S. GAAP, and certain non-cash items not otherwise described above, in each case, after discussions between the Manager and the Company's independent trustees and approval by a majority of the Company's independent trustees.

Earnings_per_Share

Earnings per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings per Share	Earnings Per Share
	Basic earnings per share, or "EPS," is calculated by dividing net income (loss) for the period by the weighted average of the Company's common shares outstanding for the period. Diluted EPS takes into account the effect of outstanding dilutive instruments, such as share options and warrants, if any, and uses the average share price for the period in determining the number of incremental shares that are to be added to the weighted average number of shares outstanding. As of December 31, 2014, 2013, and 2012, the Company did not have any dilutive instruments outstanding.
	The following table presents a reconciliation of the earnings/(losses) and shares used in calculating basic EPS for the years ended December 31, 2014 and 2013, and September 25, 2012 (commencement of operations) to December 31, 2012:
	(In thousands except for share amounts)	Year Ended		Year Ended			September 25, 2012 (commencement of operations) to
		31-Dec-14		31-Dec-13			31-Dec-12
	Numerator:
	Net income (loss)	$	16,168	$	(1,914	)	$	(536	)
	Denominator:
	Basic and diluted weighted average shares outstanding	9,142,736		6,566,656			1,633,378
	Basic and Diluted Earnings Per Share	$	1.77	$	(0.29	)	$	(0.33	)

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions
	Management Agreement
	The Company has entered into a management agreement with the Manager, which provides for an initial term through September 24, 2017, and which will be renewed automatically each year thereafter for an additional one-year period, subject to certain termination rights. The Company is externally managed and advised by the Manager. Pursuant to the terms of the Management Agreement, the Manager provides the Company with its management team, including its officers and appropriate support personnel. The Company does not have any employees. The Manager is responsible for the day-to-day operations of the Company.
	Services Agreement
	The Manager and EMG are parties to a services agreement, pursuant to which EMG is required to provide to the Manager sufficient personnel, services, and resources to enable the Manager to carry out its obligations and responsibilities under the Management Agreement. The Company is a named third-party beneficiary to the services agreement and, as a result, has, as a non-exclusive remedy, a direct right of action against EMG in the event of any breach by the Manager of any of its duties, obligations, or agreements under the Management Agreement that arise out of or result from any breach by EMG of its obligations under the services agreement. The services agreement will terminate upon the termination of the Management Agreement. Pursuant to the services agreement, the Manager makes certain payments to EMG in connection with the services provided. The Manager and EMG are under common ownership and control. As a result, all management fee compensation earned by the Manager and all service agreement fees earned by EMG accrue to the common benefit of the owners of the Manager and EMG, other than in respect of certain special non-voting membership interests in Ellington Residential Mortgage Management LLC held by certain shareholders of the Company.
	Expense Reimbursement
	Under the terms of the Management Agreement the Company is required to reimburse the Manager for operating expenses related to the Company that are incurred by the Manager, including expenses relating to legal, accounting, due diligence, other services, and all other costs and expenses. The Company's reimbursement obligation is not subject to any dollar limitation. Expenses will be reimbursed in cash within 60 days following delivery of the expense statement by the Manager; provided, however, that such reimbursement may be offset by the Manager against amounts due to the Company from the Manager. The Company will not reimburse the Manager for the salaries and other compensation of the Manager's personnel except that the Company will be responsible for expenses incurred by the Manager in employing certain dedicated or partially dedicated personnel as further described below.
	The Company reimburses the Manager for the allocable share of the compensation, including, without limitation, wages, salaries, and employee benefits paid or reimbursed, as approved by the Compensation Committee of the Board of Trustees, to certain dedicated or partially dedicated personnel who spend all or a portion of their time managing the Company's affairs, based upon the percentage of time devoted by such personnel to the Company's affairs. In their capacities as officers or personnel of the Manager or its affiliates, such personnel will devote such portion of their time to the Company's affairs as is necessary to enable the Company to operate its business.
	For the years ended December 31, 2014 and 2013, the Company reimbursed the Manager $2.3 million and $2.1 million, respectively, for previously incurred operating and compensation expenses. The Company did not make any reimbursements to the Manager prior to 2013.
	Termination Fee
	The Management Agreement requires the Company to pay a termination fee to the Manager in the event of (1) the Company's termination or non-renewal of the Management Agreement without cause or (2) the Manager's termination of the Management Agreement upon a default by the Company in the performance of any material term of the Management Agreement. Such termination fee will be equal to 5% of Shareholders' Equity, as defined in the Management Agreement (see Note 8 above) as of the month-end preceding termination.
	Registration Rights Agreement
	The Company is a party to a registration rights agreement with an affiliate of EMG and with the Blackstone Tactical Opportunities Funds (the "Blackstone Funds") pursuant to which the Company has granted its initial investors and each of their permitted transferees and other holders of the Company's "registrable common shares" (as such term is defined in the registration rights agreement) who become parties to the registration rights agreement with certain demand and/or piggy-back registration and shelf takedown rights.

Capital

Capital	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Capital	Capital
	The Company has authorized 500,000,000 common shares, $0.01 par value per share, and 100,000,000 preferred shares, $0.01 par value per share. The Board of Trustees may authorize the issuance of additional shares of either class. As of December 31, 2014 and December 31, 2013, there were 9,149,274 and 9,139,842 common shares outstanding, respectively. No preferred shares have been issued.
	On September 11, 2014, the Company's Board of Trustees authorized the issuance of 9,432 shares to its independent trustees pursuant to director share award agreements. Of these shares 6,912 will vest and become non-forfeitable on September 10, 2015; the remaining 2,520 shares vested on the date of grant.
	On September 23, 2013, the Company's Board of Trustees authorized the issuance of 6,464 shares to its independent trustees pursuant to director share award agreements. These shares vested and became non-forfeitable on April 30, 2014.
	On May 1, 2013, the Company priced an initial public offering of its common shares, pursuant to which it sold 6,450,000 shares to the public at a price of $20.00 per share. Concurrent with the initial public offering, the Company completed a private placement with its initial shareholders which resulted in gross proceeds to the Company of $21.0 million and the issuance of 1,050,000 shares at a price of $20.00. Total gross proceeds from the initial public offering and concurrent private placement were $150.0 million. Proceeds, net of offering costs, were approximately $148.5 million.
	The below table details cash dividends declared by the Board of Trustees during the year ended December 31, 2014:
		Dividend	Dividend Amount	Declaration Date	Record Date	Payment Date
		Per Share
			(In thousands)
	First Quarter	$0.55	$5,027	12-Mar-14	31-Mar-14	28-Apr-14
	Second Quarter	$0.55	$5,027	17-Jun-14	30-Jun-14	25-Jul-14
	Third Quarter	$0.55	$5,032	11-Sep-14	30-Sep-14	27-Oct-14
	Fourth Quarter	$0.55	$5,032	11-Dec-14	31-Dec-14	26-Jan-15
	The below table details cash dividends declared by the Board of Trustees during the year ended December 31, 2013:
		Dividend	Dividend Amount	Declaration Date	Record Date	Payment Date
		Per Share
			(In thousands)
	Second Quarter	$0.14	$1,279	18-Jun-13	28-Jun-13	26-Jul-13
	Third Quarter	$0.50	$4,569	17-Sep-13	27-Sep-13	25-Oct-13
	Fourth Quarter	$0.50	$4,570	12-Dec-13	31-Dec-13	27-Jan-14
	The Board of Trustees did not declare any cash dividends prior to the second quarter of 2013. On April 18, 2013, the Company's Board of Trustees declared a 3.7066% stock dividend (58,378 shares) distributable to shareholders of record as of March 31, 2013, using a price of $20.38 per share. The stock dividend was retrospectively applied to the periods reflected in the consolidated financial statements included in this Annual Report on Form 10-K.
	On August 13, 2013, the Company's Board of Trustees approved the adoption of a $10 million share repurchase program. The program, which is open-ended in duration, allows the Company to make repurchases from time to time on the open market or in negotiated transactions. Repurchases are at the Company's discretion, subject to applicable law, share availability, price and the Company's financial performance, among other considerations. No purchases have been made under the program to date.
	Distribution Policy
	The timing and frequency of distributions will be determined by the Board of Trustees based upon a variety of factors deemed relevant by the Company's trustees, including restrictions under applicable law, capital requirements of the Company, and the REIT requirements of the Code. Distributions to shareholders generally will be taxable as ordinary income, although a portion of such distributions may be designated as long-term capital gain or qualified dividend income, or may constitute a return of capital. The Company will furnish annually to each shareholder a statement setting forth distributions paid during the preceding year and their U.S. federal income tax treatment.
	It is the intention of the Company to distribute at least 100% of its taxable income, after application of available tax attributes, within the limits prescribed by the Internal Revenue Code, which may extend into the subsequent taxable year.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	From time to time, the Company may become involved in various claims and legal actions arising in the ordinary course of business. Management is not aware of any significant contingencies at December 31, 2014.

Condensed_Quarterly_Financial_

Condensed Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Condensed Quarterly Financial Data (Unaudited) [Abstract]
Quarterly Financial Information [Text Block]	Condensed Quarterly Financial Data (Unaudited)
	Detailed below is unaudited quarterly information for the years ended December 31, 2014 and 2013.
	(In thousands except for per share amounts)		Three Month Period Ended March 31, 2014			Three Month Period Ended June 30, 2014			Three Month Period Ended September 30, 2014			Three Month
												Period Ended
												31-Dec-14
	INTEREST INCOME (EXPENSE)
	Interest income		$	11,959		$	11,575		$	11,484		$	11,806
	Interest expense		(1,155		)	(1,070		)	(1,121		)	(1,165		)
	Total net interest income		10,804			10,505			10,363			10,641
	EXPENSES
	Management fees		592			567			574			552
	Professional fees		139			137			123			587
	Other operating expenses		663			613			597			608
	Total expenses		1,394			1,317			1,294			1,747
	OTHER INCOME (LOSS)
	Net realized gains (losses) on real estate securities and financial derivatives		14,556			25,806			(3,425		)	14,070
	Change in net unrealized gains (losses) on real estate securities and financial derivatives		(21,205		)	(23,944		)	(2,111		)	(24,140		)
	Total other income (loss)		(6,649		)	1,862			(5,536		)	(10,070		)
	NET INCOME (LOSS)		$	2,761		$	11,050		$	3,533		$	(1,176	)
	NET INCOME (LOSS) PER COMMON SHARE:
	Basic and Diluted		$	0.3		$	1.21		$	0.39		$	(0.13	)
	CASH DIVIDENDS PER COMMON SHARE:
	Dividends declared		$	0.55		$	0.55		$	0.55		$	0.55
	(In thousands except for per share amounts)		Three Month Period Ended March 31, 2013			Three Month Period Ended June 30, 2013			Three Month Period Ended September 30, 2013			Three Month
												Period Ended
												31-Dec-13
	INTEREST INCOME (EXPENSE)
	Interest income		$	283		$	4,310		$	11,223		$	12,050
	Interest expense		—			(525		)	(1,248		)	(1,283		)
	Total net interest income		283			3,785			9,975			10,767
	EXPENSES
	Management fees		119			703			644			600
	Professional fees		32			237			200			155
	Other operating expenses		46			421			513			656
	Total expenses		197			1,361			1,357			1,411
	OTHER INCOME (LOSS)
	Net realized gains (losses) on real estate securities and financial derivatives		888			5,370			(19,900		)	(16,504		)
	Change in net unrealized gains (losses) on real estate securities and financial derivatives		155			(17,498		)	18,067			7,024
	Total other income (loss)		1,043			(12,128		)	(1,833		)	(9,480		)
	NET INCOME (LOSS)		$	1,129		$	(9,704	)	$	6,785		$	(124	)
	NET INCOME (LOSS) PER COMMON SHARE:
	Basic and Diluted(1)		$	0.69		$	(1.55	)	$	0.74		$	(0.01	)
	CASH DIVIDENDS PER COMMON SHARE:
	Dividends declared		$	—		$	0.14		$	0.5		$	0.5
	-1	For the year ended December 31, 2013 the sum of EPS for the four quarters of 2013 does not equal EPS as calculated for the entire year (see Note 9) as a result of issuances of common shares, as EPS is calculated using average shares outstanding during the period.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events
	On March 11, 2015 the Company's Board of Trustees approved a dividend for the first quarter of 2015 in the amount of $0.55 per share payable on April 27, 2015 to shareholders of record as of March 31, 2015.

Significant_Accounting_Policie1

Significant Accounting Policies Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The Company's consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America, or "U.S. GAAP." Entities in which the Company has a controlling financial interest, through ownership of the majority of the entities' voting equity interests, or through other contractual right that give the Company control, are consolidated by the Company. All inter-company balances and transactions have been eliminated. The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates and those differences could be material.
Valuation	Valuation: The Company applies ASC 820-10, Fair Value Measurement and Disclosures ("ASC 820-10"), to its holdings of financial instruments. ASC 820-10 establishes a three-level valuation hierarchy for disclosure of fair value measurements. The valuation hierarchy is based upon the observability of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows:
	•	Level 1—inputs to the valuation methodology are observable and reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Currently, the types of financial instruments the Company generally includes in this category are, exchange-traded derivatives and cash and cash equivalents,
	•	Level 2—inputs to the valuation methodology other than quoted prices included in Level 1 are observable for the asset or liability, either directly or indirectly. Currently, the types of financial instruments that the Company generally includes in this category are Agency RMBS, non-Agency RMBS determined to have sufficiently observable market data, U.S. Treasury securities, actively traded derivatives such as TBAs, interest rate swaps, and swaptions, and
	•	Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement. Currently, this category includes RMBS where there is less price transparency.
	For certain financial instruments, the various inputs that management uses to measure fair value for such financial instrument may fall into different levels of the fair value hierarchy. In such cases, the determination of which category within the fair value hierarchy is appropriate for such financial instrument is based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the financial instrument. The Company may use valuation techniques consistent with the market and income approaches to measure the fair value of its assets and liabilities. The market approach uses third-party valuations and information obtained from market transactions involving identical or similar assets or liabilities. The income approach uses projections of the future economic benefits of an instrument to determine its fair value, such as in the discounted cash flow methodology. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risk associated with investing in these financial instruments. Transfers between levels of the fair value hierarchy are assumed to occur at the end of the reporting period.
	Summary Valuation Techniques
	For financial instruments that are traded in an "active market," the best measure of fair value is the quoted market price. However, many of the Company's financial instruments are not traded in an active market. Therefore, management generally uses third-party valuations when available. If third-party valuations are not available, management uses other valuation techniques, such as the discounted cash flow methodology. The following are summary descriptions, for the various categories of financial instruments, of the valuation methodologies management uses in determining fair value of the Company's financial instruments in such categories. Management utilizes such methodologies to assign a good faith fair value (the estimated price that, in an orderly transaction at the valuation date, would be received to sell an asset, or paid to transfer a liability, as the case may be) to each such financial instrument.
	Valuations for fixed rate RMBS pass-throughs issued by a U.S government agency or government-sponsored enterprise, or "GSE," are typically based on observable pay-up data (pay-ups are price premiums for specified categories of fixed rate pools relative to their TBA counterparts) or models that use observable market data, such as interest rates and historical prepayment speeds, and are validated against third-party valuations. With respect to the Company's other RMBS investments and TBAs, management seeks to obtain at least one third-party valuation, and often obtains multiple valuations when available. Management has been able to obtain third-party valuations on the vast majority of these instruments and expects to continue to solicit third-party valuations in the future. Management generally values each financial instrument at the average of third-party valuations received and not rejected as described below. Third-party valuations are not binding, and while management generally does not adjust the valuations it receives, management may challenge or reject a valuation when, based on its validation criteria, management determines that such valuation is unreasonable or erroneous. Furthermore, based on its validation criteria management may determine that the average of the third-party valuations received for a given instrument does not result in what management believes to be the fair value of such instrument, and in such circumstances management may override this average with its own good faith valuation. The validation criteria may take into account output from management's own models, recent trading activity in the same or similar instruments, and valuations received from third parties. The use of proprietary models requires the use of a significant amount of judgment and the application of various assumptions including, but not limited to, assumptions concerning future prepayment rates and default rates.
	Given their relatively high level of price transparency, Agency RMBS pass-throughs and TBAs are typically designated as Level 2 assets, although Agency interest only and inverse interest only RMBS are currently designated as Level 3 assets since they generally have less price transparency. Non-Agency RMBS are generally classified as either Level 2 or Level 3 based on analysis of available market data such as recent trades, executable bids, and reported "market color." Furthermore, the methodology used by the third-party valuation providers is reviewed at least annually by management, so as to ascertain whether such providers are utilizing observable market data to determine the valuations that they provide.
	Interest rate swaps and swaptions are typically valued based on internal models that use observable market data, including applicable interest rates in effect as of the measurement date; the model-generated valuations are then typically compared to counterparty valuations for reasonableness. These financial derivatives are generally designated as Level 2 instruments.
	The Company's repurchase and reverse repurchase agreements are carried at cost, which approximates fair value. Repurchase agreements and reverse repurchase agreements are classified as Level 2 assets and liabilities based on the adequacy of the collateral and their short term nature.
	The Company's valuation process, including the application of validation criteria, is overseen by the Manager's Valuation Committee. The Valuation Committee includes senior level executives from various departments within the Manager, and each quarter the Valuation Committee reviews and approves the valuations of the Company's investments. The valuation process also includes a monthly review by the Company's third party administrator. The goal of this review is to replicate various aspects of the Company's valuation process based on the Company's documented procedures.
	Because of the inherent uncertainty of valuation, the estimated fair value of the Company's financial instruments may differ significantly from the values that would have been used had a ready market for the financial instruments existed, and the differences could be material to the consolidated financial statements.
Accounting for Mortgage-Backed Securities	Accounting for Mortgage-Backed Securities: Purchases and sales of investments are recorded on trade date and realized and unrealized gains and losses are calculated based on identified cost.
	The Company has chosen to make a fair value election pursuant to ASC 825-10, Financial Instruments, for its mortgage-backed securities portfolio. Electing the fair value option allows the Company to record changes in fair value in the Consolidated Statement of Operations, which, in management's view, more appropriately reflects the results of operations for a particular reporting period as all securities activities will be recorded in a similar manner. As such, mortgage-backed securities are recorded at fair value on the Consolidated Balance Sheet and the period change in fair value is recorded in current period earnings on the Consolidated Statement of Operations as a component of Change in net unrealized gains (losses) on mortgage-backed securities.
Interest Income	Interest Income: Coupon interest income on investment securities is accrued based on the outstanding principal balance and the current coupon rate on each security. The Company amortizes premiums and accretes discounts on its fixed income securities. For RMBS that are deemed to be of high credit quality at the time of purchase, premiums and discounts are generally amortized into interest income over the life of such securities using the effective interest method. For securities subject to prepayment risk, an effective yield retroactive to the time of purchase is periodically recomputed based on actual prepayments and changes in projected prepayment activity, and a catch-up adjustment is made to amortization to reflect the cumulative impact of the change in effective yield. For RMBS that are deemed not to be of high credit quality at the time of purchase, interest income is recognized based on the effective interest method. For purposes of determining the effective interest rate, management estimates the future expected cash flows of its investment holdings based on assumptions including, but not limited to, assumptions for future prepayment rates, default rates, and loss severities (each of which may in turn incorporate various macro-economic assumptions, such as future housing prices). These assumptions are re-evaluated not less than quarterly. Principal write-offs are generally treated as realized losses. Changes in projected cash flows, as applied to the current amortized cost of the security, may result in a prospective change in the yield/interest income recognized on such securities.
	The Company's accretion of discounts and amortization of premiums on securities for U.S. federal and other tax purposes is likely to differ from the accounting treatment under U.S. GAAP of these items as described above.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents include cash and short term investments with original maturities of three months or less at the date of acquisition. Cash equivalents are recorded at cost plus accrued interest, which approximates fair value. Cash and cash equivalents typically include amounts held in an interest bearing overnight account and amounts held in money market funds, and these balances generally exceed insured limits.
Deposits with Dealers Held as Collateral/Due to Brokers	Due from brokers/Due to brokers: Due from brokers and Due to brokers accounts on the Consolidated Balance Sheet include collateral transferred to or received from counterparties, including clearinghouses, along with receivables and payables for open and/or closed derivative positions.
Financial Derivatives	Financial Derivatives: The Company may enter into various types of financial derivatives subject to its investment guidelines, which include restrictions associated with maintaining qualification as a REIT. The Company's financial derivatives are predominantly subject to bilateral collateral arrangements or clearing in accordance with the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010. The Company may be required to deliver or may receive cash or securities as collateral upon entering into derivative transactions. In addition, changes in the relative value of financial derivative transactions may require the Company or the counterparty to post or receive additional collateral. In the case of cleared financial derivatives, the clearinghouse becomes the Company's counterparty and a futures commission merchant acts as intermediary between the Company and the clearinghouse with respect to all facets of the related transaction, including the posting and receipt of required collateral. Collateral received by the Company is reflected on the Consolidated Balance Sheet as "Due to Brokers." Conversely, collateral posted by the Company is reflected as "Due from Brokers" on the Consolidated Balance Sheet. The types of financial derivatives that have been utilized by the Company to date are interest rate swaps, TBAs, swaptions, and futures.
	Swaps: The Company has entered into interest rate swaps, which are contractual agreements whereby one party pays a floating interest rate on a notional principal amount and receives a fixed rate payment on the same notional principal, or vice versa, for a fixed period of time.
	Swaps change in value with movements in interest rates or total return of the reference securities. During the term of swap contracts, changes in value are recognized as unrealized gains or losses on the Consolidated Statement of Operations. When a contract is terminated, the Company realizes a gain or loss equal to the difference between the proceeds from (or cost of) the closing transaction and the Company's basis in the contract, if any. Periodic payments or receipts required by swap agreements are recorded as unrealized gains or losses when accrued and realized gains or losses when received or paid. Upfront payments paid and/or received by the Company to open swap contracts are recorded as an asset and/or liability on the Consolidated Balance Sheet and are recorded as a realized gain or loss on the termination date.
	TBA Securities: The Company has transacted in the forward settling TBA market. A TBA position is a forward contract for the purchase ("long position") or sale ("short position") of Agency RMBS at a predetermined price, face amount, issuer, coupon, and maturity on an agreed-upon future delivery date. For each TBA contract and delivery month, a uniform settlement date for all market participants is determined by the Securities Industry and Financial Markets Association. The specific Agency RMBS to be delivered into the contract at the settlement date are not known at the time of the transaction. The Company typically does not take delivery of TBAs, but rather enters into offsetting transactions and settles the associated receivable and payable balances with its counterparties. The Company primarily uses TBAs to mitigate interest rate risk, but from time to time it also holds net long positions in certain TBA securities as a means of acquiring exposure to Agency RMBS.
	TBAs are accounted for by the Company as financial derivatives. The difference between the contract price and the fair value of the TBA position as of the reporting date is included in Change in net unrealized gains (losses) on financial derivatives, in the Consolidated Statement of Operations. Upon settlement of the TBA contract, the realized gain (loss) on the TBA contract is equal to the net cash amount received (paid).
	Options: The Company has entered into swaption contracts. It may purchase or write put, call, straddle, or other similar options contracts. The Company enters into options contracts primarily to help mitigate interest rate risk. When the Company purchases an options contract, the option asset is initially recorded at an amount equal to the premium paid, if any, and is subsequently marked-to-market. Premiums paid for purchasing options contracts that expire unexercised are recognized on the expiration date as realized losses. If an options contract is exercised, the premium paid is subtracted from the proceeds of the sale or added to the cost of the purchase to determine whether the Company has realized a gain or loss on the related investment transaction. When the Company writes an options contract, the option liability is initially recorded at an amount equal to the premium received, if any, and is subsequently marked-to-market. Premiums received for writing options contracts that expire unexercised are recognized on the expiration date as realized gains. If an options contract is exercised, the premium received is subtracted from the cost of the purchase or added to the proceeds of the sale to determine whether the Company has realized a gain or loss on the related investment transaction. When the Company enters into a closing transaction, the Company will realize a gain or loss depending upon whether the amount from the closing transaction is greater or less than the premiums paid or received. In general, the Company's options contracts contain forward-settling premiums. In this case, no money is exchanged upfront; instead, the agreed-upon premium is paid by the buyer upon expiration of the options contract, regardless of whether or not the options contract is exercised.
	Futures Contracts: A futures contract is an exchange-traded agreement to buy or sell an asset for a set price on a future date. Initial margin deposits are made upon entering into futures contracts and can be either in the form of cash or securities. During the period the futures contract is open, changes in the value of the contract are recognized as unrealized gains or losses by marking-to-market to reflect the current market value of the contract. Variation margin payments are made or received periodically, depending upon whether unrealized losses or gains are incurred. When the contract is closed, the Company records a realized gain or loss equal to the difference between the proceeds of the closing transaction and the Company's basis in the contract.
	Financial derivative assets are included in Financial derivatives–assets, at fair value on the Consolidated Balance Sheet while financial derivative liabilities are included in Financial derivatives–liabilities, at fair value on the Consolidated Balance Sheet.
Repurchase Agreements and Reverse Repurchase Agreements	Repurchase Agreements and Reverse Repurchase Agreements: The Company enters into repurchase agreements with third-party broker-dealers, whereby it sells securities under agreements to repurchase at an agreed upon price and date. The Company also enters into reverse repurchase agreement transactions with third-party broker-dealers, whereby it purchases securities under agreements to resell at an agreed upon price and date. The Company accounts for repurchase agreements as collateralized borrowings, with the initial sale price representing the amount borrowed, and with the future repurchase price consisting of the amount borrowed plus interest, at the implied interest rate of the repurchase agreement, on the amount borrowed over the term of the repurchase agreement. The interest rate on a repurchase agreement or a reverse repurchase agreement is based on competitive market rates (or competitive market spreads, in the case of agreements with floating interest rates) at the time such agreement is entered into. When the Company enters into a repurchase agreement, the lender establishes and maintains an account containing cash and/or securities having a value not less than the repurchase price, including accrued interest, of the repurchase agreement. Repurchase and reverse repurchase agreements that are conducted with the same counterparty can be reported on a net basis if they meet the requirements under the authoritative guidance. Repurchase agreements and reverse repurchase agreements are carried at their contractual amounts, which approximate fair value.
U.S. Treasury securities	U.S. Treasury Securities: The Company may purchase or sell short U.S. Treasury securities to help mitigate the potential impact of changes in interest rates on the performance of its portfolio. The Company may borrow securities under reverse repurchase agreements to enable it to deliver U.S. Treasury securities that it has sold short.
Organizational Expense	Organizational Expenses: Organizational expenses are expensed as incurred. Organizational expenses incurred by the Company consisted mainly of legal fees.
Offering Costs/Deferred Offering Costs	Offering Costs/Deferred Offering Costs: Offering costs are charged against shareholders' equity and typically include legal, accounting, printing, and other fees associated with the cost of raising equity capital.
Share Based Compensation	Share Based Compensation: The Company applies the provisions of ASC 718, Compensation—Shares Compensation ("ASC 718"), with regard to its equity incentive plans. ASC 718 covers a wide range of share-based compensation arrangements including share options, restricted share plans, performance-based awards, share appreciation rights, and employee share purchase plans. ASC 718 requires that compensation cost relating to share-based payment transactions be recognized in financial statements. The cost is measured based on the fair value of the equity or liability instruments issued.
Dividends	Dividends: Dividends payable are recorded on the declaration date.
Earnings Per Share	Earnings Per Share: In accordance with the provisions of ASC 260, Earnings per Share, the Company calculates basic income (loss) per share by dividing net income (loss) for the period by the weighted average of the Company's common shares outstanding for that period. Diluted income (loss) per share takes into account the effect of dilutive instruments, such as share options and warrants, and uses the average share price for the period in determining the number of incremental shares that are to be added to the weighted average number of shares outstanding.
Share repurchases [Policy Text Block]	Share Repurchases: Common shares that are repurchased by the Company subsequent to issuance decrease the total number of shares issued and outstanding.
Income Taxes	Income Taxes: Prior to May 1, 2013, the Company, as a business trust with more than one owner, was considered a partnership for U.S. federal income tax purposes. In general, partnerships are not subject to entity-level tax on their income, but the income of a partnership is taxable to its owners on a flow-through basis. For the periods September 25, 2012 (commencement of operations) through December 31, 2012 and January 1, 2013 through April 30, 2013, the Company filed its tax return as a partnership. Effective May 1, 2013, the Company made the election to be taxed as a corporation. In addition, the Company elected to be taxed as a REIT under Sections 856 to 860 of the Code commencing with the short taxable period May 1, 2013 through December 31, 2013. As a REIT, the Company is generally not subject to corporate-level federal and state income tax on net income it distributes to its stockholders. To qualify as a REIT, the Company must meet a number of organizational and operational requirements, including the distribution of at least 90% of its annual taxable income to shareholders. Even if the Company qualifies as a REIT, it may be subject to certain federal, state, local and foreign taxes on its income and property and to federal income and excise taxes on its undistributed taxable income.
	The Company follows the authoritative guidance on accounting for and disclosure of uncertainty on tax positions, which requires management to determine whether a tax position of the company is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals of the litigation process, based on the technical merits of the position. For uncertain tax positions, the tax benefit to be recognized is measured as the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company did not have any unrecognized tax benefits at December 31, 2014. In the normal course of business, the Company may be subject to examination by federal, state, local, and foreign jurisdictions, where applicable, for the current period, 2013, and 2012 (its open tax years). The Company may take positions with respect to certain tax issues which depend on legal interpretation of facts or applicable tax regulations. Should the relevant tax regulators successfully challenge any of such positions, the Company might be found to have a tax liability that has not been recorded in the accompanying consolidated financial statements. Also, management's conclusions regarding the authoritative guidance may be subject to review and adjustment at a later date based on changing tax laws, regulations, and interpretations thereof. There were no amounts accrued for penalties or interest as of or during the periods presented in these consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements: Under the Jumpstart Our Business Startups Act, or the "JOBS Act," the Company meets the definition of an "emerging growth company." The Company has elected to follow the extended transition period for complying with new or revised U.S. accounting standards pursuant to Section 107(b) of the JOBS Act. As a result, the Company will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-public entities.
	In June 2014, the FASB issued ASU No. 2014-11, Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures ("ASU 2014-11"). This amends ASC 860, Transfers and Servicing ("ASC 860"), to require disclosure of repurchase-to-maturity transactions to be accounted for as secured borrowings rather than sales of an asset, and transfers of financial assets with a contemporaneous repo will no longer be evaluated to determine whether they should be accounted for on a combined basis as forward contracts. The new guidance also prescribes additional disclosures particularly on the nature of collateral pledged under repurchase agreements accounted for as secured borrowings. ASU 2014-11 is effective for annual periods beginning after December 15, 2014 and interim periods beginning after December 31, 2015. The adoption of ASC 860, as amended by ASU 2014-11 is not expected to have a material impact on the Company's consolidated financial statements.
	In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern ("ASU 2014-15"). ASU 2014-15 requires management to perform interim and annual assessments of an entity's ability to continue as a going concern and to provide disclosure if events or conditions arise that would place substantial doubt on the entity's ability to continue as a going concern. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and subsequent interim and annual periods with early adoption permitted. The adoption of ASU 2014-15 is not expected to have a material impact on the Company's consolidated financial statements.
	In February 2015, the FASB issued ASU 2015-02, Amendments to the Consolidation Analysis ("ASU 2015-02"). This amends ASC 810, Consolidation (ASC "810"), to improve targeted areas of consolidation guidance by simplifying the requirements of consolidation and placing more emphasis on risk of loss when determining a controlling financial interest. ASU 2015-02 is effective for the annual period ending after December 15, 2015, and subsequent interim and annual periods with early adoption permitted. The adoption of ASU 2015-02 is not expected to have a material impact on the Company's consolidated financial statements.

MortgageBacked_Securities_Tabl

Mortgage-Backed Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Mortgage-backed securities [Table Text Block]	The following tables present details of the Company's mortgage-backed securities portfolio at December 31, 2014 and December 31, 2013, respectively. The Company's Agency RMBS include mortgage pass-through certificates and CMOs representing interests in or obligations backed by pools of residential mortgage loans issued or guaranteed by a U.S. government agency or GSE. The non-Agency RMBS portfolio is not issued or guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, or any agency of the U.S. Government and is therefore subject to greater credit risk.
	By RMBS Type –
	December 31, 2014:
	($ in thousands)											Gross Unrealized											Weighted Average
		Current Principal			Unamortized Premium (Discount)				Amortized			Gains			Losses				Fair Value				Coupon		Yield		Weighted Average Life(Years)(1)
									Cost
	Agency RMBS:
	15-year fixed rate mortgages	$	130,720		$	6,304			$	137,024		$	1,113		$	(109	)		$	138,028			3.40%		2.46%		5.43
	20-year fixed rate mortgages	9,764			577				10,341			227			—				10,568				4.00%		3.04%		6.92
	30-year fixed rate mortgages	1,042,550			61,089				1,103,639			20,379			(1,764		)		1,122,254				4.09%		3.29%		8.48
	Adjustable rate mortgages	41,710			2,813				44,523			90			(330		)		44,283				4.60%		3.08%		5.97
	Reverse mortgages	31,412			2,741				34,153			300			(28		)		34,425				4.91%		2.56%		4.74
	Interest only securities	n/a			n/a				10,780			1,190			(726		)		11,244				4.04%		11.82%		2.68
	Total Agency RMBS	1,256,156			73,524				1,340,460			23,299			(2,957		)		1,360,802				4.05%		3.24%		7.54
	Non-Agency RMBS	50,668			(20,377		)		30,291			2,896			(686		)		32,501				2.29%		10.76%		4.97
	Total RMBS	$	1,306,824		$	53,147			$	1,370,751		$	26,195		$	(3,643	)		$	1,393,303			3.99%		3.41%		7.45
	-1	Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal.
	December 31, 2013:
	($ in thousands)											Gross Unrealized											Weighted Average
		Current Principal			Unamortized Premium (Discount)				Amortized			Gains			Losses				Fair Value				Coupon		Yield		Weighted Average Life(Years)(1)
									Cost
	Agency RMBS:
	15-year fixed rate mortgages	$	179,906		$	7,153			$	187,059		$	65		$	(3,252	)		$	183,872			3.09%		2.52%		5.76
	30-year fixed rate mortgages	1,029,629			41,565				1,071,194			490			(28,111		)		1,043,573				3.79%		3.30%		9.8
	Adjustable rate mortgages	43,525			2,647				46,172			46			(103		)		46,115				4.72%		3.24%		3.79
	Reverse mortgages	7,581			673				8,254			16			(2		)		8,268				4.85%		2.90%		3.41
	Interest only securities	n/a			n/a				10,718			2,841			(32		)		13,527				3.97%		11.79%		5.02
	Total Agency RMBS	1,260,641			52,038				1,323,397			3,458			(31,500		)		1,295,355				3.75%		3.26%		8.67
	Non-Agency RMBS	50,006			(21,327		)		28,679			2,196			(194		)		30,681				2.84%		9.12%		5.54
	Total RMBS	$	1,310,647		$	30,711			$	1,352,076		$	5,654		$	(31,694	)		$	1,326,036			3.72%		3.38%		8.56
	-1	Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal.
Weighted Average Life Classifications [Table Text Block]	By Estimated Weighted Average Life
	As of December 31, 2014:
	($ in thousands)		Agency RMBS									Agency Interest Only Securities										Non-Agency RMBS
	Estimated Weighted Average Life		Fair			Amortized Cost				Weighted Average Coupon		Fair Value			Amortized Cost				Weighted Average Coupon			Fair Value				Amortized Cost				Weighted Average Coupon
			Value
	Less than three years		$	18,428		$	18,418			5.13	%	$	5,197		$	5,563			3.42	%		$	2,837			$	1,785			3.02	%
	Greater than three years and less than seven years		410,759			405,739				4.12	%	6,047			5,217				5.19	%		17,660				17,662				2.63	%
	Greater than seven years and less than eleven years		920,371			905,523				4	%	—			—				—	%		12,004				10,844				1.28	%
	Total		$	1,349,558		$	1,329,680			4.05	%	$	11,244		$	10,780			4.04	%		$	32,501			$	30,291			2.29	%
	As of December 31, 2013:
	($ in thousands)		Agency RMBS									Agency Interest Only Securities										Non-Agency RMBS
	Estimated Weighted Average Life		Fair			Amortized Cost				Weighted Average Coupon		Fair Value			Amortized Cost				Weighted Average Coupon			Fair Value				Amortized Cost				Weighted Average Coupon
			Value
	Less than three years		$	5,554		$	5,518			5.68	%	$	955		$	762			6.48	%		$	1,715			$	1,216			2.38	%
	Greater than three years and less than seven years		243,120			246,342				3.48	%	7,643			6,198				3.31	%		16,488				15,950				3.42	%
	Greater than seven years and less than eleven years		1,031,552			1,059,223				3.79	%	4,929			3,758				4.91	%		11,656				10,708				1.43	%
	Greater than eleven years		1,602			1,596				4.5	%	—			—				—	%		822				805				7.69	%
	Total		$	1,281,828		$	1,312,679			3.73	%	$	13,527		$	10,718			3.97	%		$	30,681			$	28,679			2.84	%
Interest Income Components - Investments [Table Text Block]	The following table illustrates components of interest income on the Company's RMBS for the years ended December 31, 2014 and 2013 and September 25, 2012 (commencement of operations) to December 31, 2012:
			Year Ended										Year Ended											25-Sep-12
			31-Dec-14										31-Dec-13											(commencement of operations) to
																								31-Dec-12
	($ in thousands)		Coupon Interest			Net Amortization				Interest			Coupon Interest			Net Amortization				Interest				Coupon Interest				Net Amortization				Interest
										Income										Income												Income
	Agency RMBS		$	52,755		$	(9,112	)		$	43,643		$	30,504		$	(4,863	)		$	25,641			$	—			$	—			$	—
	Non-Agency RMBS		1,237			1,930				3,167			1,185			952				2,137				125				114				239
	Total		$	53,992		$	(7,182	)		$	46,810		$	31,689		$	(3,911	)		$	27,778			$	125			$	114			$	239

Valuation_Tables

Valuation (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Schedule of Fair Value Measurements	The following tables present the Company's financial instruments measured at fair value on:
	December 31, 2014:
	(In thousands)
	Description		Level 1			Level 2			Level 3			Total
	Assets:
	Mortgage-backed securities, at fair value:
	Agency RMBS:
	15-year fixed rate mortgages		$	—		$	138,028		$	—		$	138,028
	20-year fixed rate mortgages		—			10,568			—			10,568
	30-year fixed rate mortgages		—			1,122,254			—			1,122,254
	Adjustable rate mortgages		—			44,283			—			44,283
	Reverse mortgages		—			34,425			—			34,425
	Interest only securities		—			—			11,244			11,244
	Non-Agency RMBS		—			22,419			10,082			32,501
	Mortgage-backed securities, at fair value		—			1,371,977			21,326			1,393,303
	Financial derivatives–assets, at fair value:
	TBAs		—			476			—			476
	Fixed payer interest rate swaps		—			2,518			—			2,518
	Fixed payer swaptions		—			78			—			78
	Total financial derivatives–assets, at fair value		—			3,072			—			3,072
	Reverse repurchase agreements		—			13,987			—			13,987
	Total mortgage-backed securities, financial derivatives–assets, and reverse repurchase agreements, at fair value		$	—		$	1,389,036		$	21,326		$	1,410,362
	Liabilities:
	U.S. Treasury securities sold short, at fair value		$	—		$	(13,959	)	$	—		$	(13,959	)
	Financial derivatives–liabilities, at fair value:
	TBAs		—			(1,674		)	—			(1,674		)
	Fixed payer interest rate swaps		—			(7,026		)	—			(7,026		)
	Total financial derivatives–liabilities, at fair value		$	—		$	(8,700	)	$	—		$	(8,700	)
	Total U.S. Treasury securities and financial derivatives–liabilities, at fair value		$	—		$	(22,659	)	$	—		$	(22,659	)
	There were no transfers of financial instruments between Levels 1 and 2 of the fair value hierarchy during the year ended December 31, 2014.
	December 31, 2013:
	(In thousands)
	Description		Level 1			Level 2			Level 3			Total
	Assets:
	Mortgage-backed securities, at fair value:
	Agency RMBS:
	15-year fixed rate mortgages		$	—		$	183,872		$	—		$	183,872
	30-year fixed rate mortgages		—			1,043,573			—			1,043,573
	Adjustable rate mortgages		—			46,115			—			46,115
	Reverse mortgages		—			8,268			—			8,268
	Interest only securities		—			—			13,527			13,527
	Non-Agency RMBS		—			—			30,681			30,681
	Mortgage-backed securities, at fair value		—			1,281,828			44,208			1,326,036
	Financial derivatives–assets, at fair value:
	TBAs		—			2,263			—			2,263
	Fixed payer interest rate swaps		—			32,700			—			32,700
	Total financial derivatives–assets, at fair value		—			34,963			—			34,963
	Total mortgage-backed securities and financial derivatives–assets, at fair value		$	—		$	1,316,791		$	44,208		$	1,360,999
	Liabilities:
	Financial derivatives–liabilities, at fair value:
	TBAs		$	—		$	(28	)	$	—		$	(28	)
	Fixed payer interest rate swaps		—			(956		)	—			(956		)
	Fixed payer swaptions		—			(85		)	—			(85		)
	Total financial derivatives–liabilities, at fair value		$	—		$	(1,069	)	$	—		$	(1,069	)
	There were no transfers of financial instruments between Levels 1, 2, or 3 of the fair value hierarchy during the year ended December 31, 2013.
Unobservable Input Reconciliation	The following tables present additional information about the Company's investments which are measured at fair value for which the Company has utilized Level 3 inputs to determine fair value:
	Year ended December 31, 2014:
	(In thousands)	Non-Agency RMBS			Agency RMBS
	Beginning balance as of December 31, 2013	$	30,681		$	13,527
	Purchases	14,712			4,853
	Proceeds from sales	(11,104		)	(2,330		)
	Principal repayments	(5,443		)	—
	(Amortization)/accretion, net	1,930			(3,136		)
	Net realized gains	1,518			676
	Change in net unrealized gains (losses)	207			(2,346		)
	Transfers:
	Transfers into level 3	—			—
	Transfers out of level 3	(22,419		)	—
	Ending balance as of December 31, 2014	$	10,082		$	11,244
	All amounts of net realized and changes in net unrealized gains (losses) in the table above are reflected in the accompanying Consolidated Statement of Operations. The table above incorporates changes in net unrealized gains (losses) for both Level 3 financial instruments held by the Company at December 31, 2014, as well as Level 3 financial instruments disposed of by the Company during the year ended December 31, 2014. For Level 3 financial instruments held by the Company at December 31, 2014, change in net unrealized gains (losses) of $0.7 million and $(2.0) million, for the year ended December 31, 2014 relate to non-Agency RMBS and Agency RMBS, respectively.
	At December 31, 2014, the Company transferred $22.4 million of non-Agency RMBS from Level 3 to Level 2. The decision to transfer these assets from Level 3 to Level 2 was based on observed market developments, including an increased volume of buying and selling of these and similar assets, greater consensus among market participants on price based on market quotes, and generally tighter credit spreads driven by improved performance in the underlying collateral as well as increased demand from investors seeking higher yielding assets. These factors have led to greater price transparency for these assets, thereby making a Level 2 designation appropriate in the Company's view. However, changes in observed market developments could impact future price transparency, and thereby cause a change in the level designation in subsequent periods.
	Year ended December 31, 2013:
	(In thousands)	Non-Agency RMBS			Agency RMBS
	Beginning balance as of December 31, 2012	$	13,596		$	—
	Purchases	41,734			12,167
	Proceeds from sales	(23,007		)	—
	Principal repayments	(5,923		)	—
	(Amortization)/accretion, net	952			(1,449		)
	Net realized gains	1,433			—
	Change in net unrealized gains (losses)	1,896			2,809
	Transfers:
	Transfers into level 3	—			—
	Transfers out of level 3	—			—
	Ending balance as of December 31, 2013	$	30,681		$	13,527
	All amounts of net realized and changes in net unrealized gains (losses) in the table above are reflected in the accompanying Consolidated Statement of Operations. The table above incorporates changes in net unrealized gains (losses) for both Level 3 financial instruments held by the Company at December 31, 2013, as well as Level 3 financial instruments disposed of by the Company during the year ended December 31, 2013. For Level 3 financial instruments held by the Company at December 31, 2013, change in net unrealized gains (losses) of $2.0 million and $2.8 million, for the year ended December 31, 2013 relate to non-Agency RMBS and Agency RMBS, respectively.
	September 25, 2012 (commencement of operations) to December 31, 2012:
	(In thousands)	Non-Agency RMBS
	Beginning balance as of September 25, 2012	$	—
	Purchases	13,643
	Proceeds from sales	(248		)
	Principal repayments	—
	(Amortization)/accretion, net	114
	Net realized losses	(19		)
	Change in net unrealized gains (losses)	106
	Transfers:
	Transfers into level 3	—
	Transfers out of level 3	—
	Ending balance as of December 31, 2012	$	13,596
	All amounts of net realized and changes in net unrealized gains (losses) in the table above are reflected in the accompanying Consolidated Statement of Operations. The table above incorporates changes in net unrealized gains (losses) for both Level 3 financial instruments held by the Company at December 31, 2012, as well as Level 3 financial instruments disposed of by the Company during the period September 25, 2012 (commencement of operations) to December 31, 2012. For Level 3 financial instruments held by the Company at December 31, 2013, change in net unrealized gains (losses) of $0.1 million for the period September 25, 2012 (commencement of operations) to December 31, 2012 relate to non-Agency RMBS.
Quantitative Information	The following tables identify the significant unobservable inputs that affect the valuation of the Company's Level 3 assets and liabilities as of December 31, 2014 and December 31, 2013:
	December 31, 2014:
									Range
	Description		Fair Value			Valuation Technique		Significant	Min			Max			Weighted Average(1)
								Unobservable Input
			(In thousands)
	Non-Agency RMBS		$	7,819		Market quotes		Non-Binding Third-Party Valuation	$	21.38		$	84.91		$	54.11
	Non-Agency RMBS		2,263			Discounted Cash Flows		Yield	6.3		%	6.3		%	6.3		%
								Projected Collateral Prepayments	35.9		%	35.9		%	35.9		%
								Projected Collateral Losses	7.5		%	7.5		%	7.5		%
								Projected Collateral Recoveries	11		%	11		%	11		%
								Projected Collateral Scheduled Amortization	45.6		%	45.6		%	45.6		%
															100		%
	Agency RMBS–Interest Only Securities		7,006			Market quotes		Non-Binding Third-Party Valuation	$	4.74		$	20.38		$	13.35
	Agency RMBS–Interest Only Securities		4,238			Option Adjusted Spread ("OAS")		LIBOR OAS (2)	83			1,952			490
								Projected Collateral Prepayments	63.3		%	92.3		%	75.2		%
								Projected Collateral Scheduled Amortization	7.7		%	36.7		%	24.8		%
															100		%
	-1	Averages are weighted based on the fair value of the related instrument.
	-2	Shown in basis points.
	December 31, 2013:
									Range
	Description		Fair Value			Valuation Technique		Significant	Min			Max			Weighted Average(1)
								Unobservable Input
			(In thousands)
	Non-Agency RMBS		$	27,422		Market quotes		Non-Binding Third-Party Valuation	$	20		$	100.25		$	75.39
	Non-Agency RMBS		3,259			Discounted Cash Flows		Yield	6		%	17		%	11.9		%
								Projected Collateral Prepayments	12.2		%	58.1		%	33.9		%
								Projected Collateral Losses	6.4		%	26.5		%	11.8		%
								Projected Collateral Recoveries	4.6		%	12.8		%	8.8		%
								Projected Collateral Scheduled Amortization	29.9		%	54.9		%	45.5		%
															100		%
	Agency RMBS–Interest Only Securities		12,368			Market quotes		Non-Binding Third-Party Valuation	$	4.99		$	22.47		$	14.92
	Agency RMBS–Interest Only Securities		1,159			Option Adjusted Spread ("OAS")		LIBOR OAS(2)	436			436			436
								Projected Collateral Prepayments	57.8		%	57.8		%	57.8		%
								Projected Collateral Scheduled Amortization	42.2		%	42.2		%	42.2		%
															100		%
	-1	Averages are weighted based on the fair value of the related instrument.
	-2	Shown in basis points.

Derivative_Instruments_Tables

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments [Abstract]
Schedule of Derivative Instruments [Table Text Block]	The following table details fair value of the Company's holdings of financial derivatives as of December 31, 2014 and December 31, 2013:
			31-Dec-14			31-Dec-13
			(In thousands)
	Financial derivatives–assets, at fair value:
	TBA securities purchase contracts		$	387		$	1
	TBA securities sale contracts		89			2,262
	Fixed payer interest rate swaps		2,518			32,700
	Swaptions		78			—
	Total financial derivatives–assets, at fair value:		3,072			34,963
	Financial derivatives–liabilities, at fair value:
	TBA securities purchase contracts		(5		)	—
	TBA securities sale contracts		(1,669		)	(28		)
	Fixed payer interest rate swaps		(7,026		)	(956		)
	Swaptions		—			(85		)
	Total financial derivatives–liabilities, at fair value:		(8,700		)	(1,069		)
	Total		$	(5,628	)	$	33,894
Interest Rate Swaps By Remaining Maturity [Table Text Block]	The following tables provide information about the Company's interest rate swaps as of December 31, 2014 and December 31, 2013:
	December 31, 2014:
										Weighted Average
	Remaining Maturity		Notional Amount			Fair Value				Pay Rate			Receive Rate			Remaining Years to Maturity
			(In thousands)
	2016		$	48,000		$	(91	)		0.8	%		0.23	%		1.77
	2017		74,750			(388		)		1.21			0.24			2.59
	2018		10,000			167				0.84			0.23			3.33
	2020		23,500			471				1.42			0.23			5.38
	2023		209,350			140				2.13			0.23			8.4
	2024		12,900			(605		)		2.73			0.23			9.45
	2043		46,320			(4,202		)		3.12			0.23			28.42
	Total		$	424,820		$	(4,508	)		1.87	%		0.23	%		8.56
	December 31, 2013:
										Weighted Average
	Remaining Maturity		Notional Amount			Fair Value				Pay Rate			Receive Rate			Remaining Years to Maturity
			(In thousands)
	2016		$	48,000		$	(171	)		0.8	%		0.24	%		2.77
	2017		124,000			(517		)		1.19			0.24			3.61
	2018		156,500			2,784				1.19			0.24			4.63
	2020		137,100			6,444				1.49			0.24			6.06
	2023		218,000			14,599				2.16			0.24			9.41
	2043		64,750			8,605				3.18			0.24			29.44
	Total		$	748,350		$	31,744			1.67	%		0.24	%		8.14
Swaptions [Table Text Block]	The following tables provide information about the Company's swaptions as of December 31, 2014 and December 31, 2013.
	December 31, 2014:
	Option							Underlying Swap
	Type		Fair Value			Months to Expiration		Notional				Term (Years)
								Amount						Fixed Rate
	($ in thousands)
	Straddle		$	78		6.5		$	9,700			10		3.00%
	December 31, 2013:
	Option							Underlying Swap
	Type		Fair Value			Months to Expiration		Notional				Term (Years)		Fixed Rate
								Amount
	($ in thousands)
	Fixed Payer		$	(59	)	8.9		$	22,000			10		3.31%
	Straddle		$	(26	)	9.9		$	8,000			10		3.08%
Schedule of To-be-announced securities (TBAs) [Table Text Block]	As of December 31, 2014 and December 31, 2013, the Company had outstanding contracts to purchase ("long positions") and sell ("short positions") TBA securities as follows:
			31-Dec-14														31-Dec-13
	TBA Securities		Notional Amount(1)			Cost				Market Value(3)				Net Carrying Value(4)			Notional Amount (1)			Cost			Market Value(3)			Net Carrying Value(4)
						Basis(2)														Basis(2)
	(In thousands)
	Purchase contracts:
	Assets		$	53,319		$	54,757			$	55,144			$	387		$	1,600		$	1,725		$	1,726		$	1
	Liabilities		15,000			15,603				15,598				(5		)	—			—			—			—
			68,319			70,360				70,742				382			1,600			1,725			1,726			1
	Sale contracts:
	Assets		(79,090		)	(85,730		)		(85,641		)		89			(363,078		)	(375,524		)	(373,262		)	2,262
	Liabilities		(525,986		)	(559,219		)		(560,888		)		(1,669		)	(16,400		)	(17,518		)	(17,546		)	(28		)
			(605,076		)	(644,949		)		(646,529		)		(1,580		)	(379,478		)	(393,042		)	(390,808		)	2,234
	Total TBA securities, net		$	(536,757	)	$	(574,589	)		$	(575,787	)		$	(1,198	)	$	(377,878	)	$	(391,317	)	$	(389,082	)	$	2,235
	-1	Notional amount represents the principal balance of the underlying Agency RMBS.
	-2	Cost basis represents the forward price to be paid for the underlying Agency RMBS.
	-3	Market value represents the current market value of the underlying Agency RMBS (on a forward delivery basis) as of period end.
	-4	Net carrying value represents the difference between the market value of the TBA contract as of period end and the cost basis and is reported in Financial derivatives-assets at fair value and Financial derivatives-liabilities at fair value on the Consolidated Balance Sheet.
Derivative Activity, Volume [Table Text Block]	The tables below detail the average notional values of the Company's financial derivatives, using absolute value of month end notional values, for the years ended December 31, 2014 and 2013:
	Derivative Type		Year Ended December 31, 2014			Year Ended December 31, 2013
			(In thousands)
	Interest rate swaps		$	566,379		$	609,310
	TBAs		545,646			364,943
	Interest rate swaptions		20,631			11,200
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]	Gains and losses on the Company's financial derivatives for the years ended December 31, 2014 and 2013 are summarized in the tables below:
			Year Ended December 31, 2014
	Derivative Type		Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps			Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps				Net Realized Gains (Losses) on Financial Derivatives				Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) on Financial Derivatives
	(In thousands)
	Fixed payer interest rate swaps		$	(9,217	)	$	1,823			$	(7,394	)		$	410		$	(36,662	)	$	(36,252	)
	Swaptions					(935		)		(935		)					163			163
	TBAs					(23,568		)		(23,568		)					(3,433		)	(3,433		)
	Futures					19				19							—			—
	Total		$	(9,217	)	$	(22,661	)		$	(31,878	)		$	410		$	(39,932	)	$	(39,522	)
			Year Ended December 31, 2013
	Derivative Type		Net Realized Gains (Losses) on Periodic Settlements of Interest Rate Swaps			Net Realized Gains (Losses) Other Than Periodic Settlements of Interest Rate Swaps				Net Realized Gains (Losses) on Financial Derivatives				Change in Net Unrealized Gains (Losses) on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps			Change in Net Unrealized Gains (Losses) on Financial Derivatives
	(In thousands)
	Fixed payer interest rate swaps		$	(5,200	)	$	5,060			$	(140	)		$	(1,538	)	$	33,282		$	31,744
	Swaptions					—				—							(85		)	(85		)
	TBAs					7,450				7,450							2,235			2,235
	Total		$	(5,200	)	$	12,510			$	7,310			$	(1,538	)	$	35,432		$	33,894

Borrowings_under_Repurchase_Ag1

Borrowings under Repurchase Agreements (Tables)	12 Months Ended
	Dec. 31, 2014
Repurchase Agreements [Abstract]
Schedule of Repurchase Agreements [Table Text Block]	The following table details the Company's outstanding borrowings under repurchase agreements as of December 31, 2014 and December 31, 2013:
		December 31, 2014					31-Dec-13
				Weighted Average					Weighted Average
	Remaining Days to Maturity	Borrowings Outstanding		Interest Rate		Remaining Days to Maturity	Borrowings Outstanding		Interest Rate		Remaining Days to Maturity
		(In thousands)
	30 days or less	$	437,633	0.33	%	15	$	338,700	0.35	%	14
	31-60 days	417,009		0.34		44	531,799		0.39		46
	61-90 days	333,580		0.36		72	326,386		0.38		72
	91-120 days	—		—		—	109,476		0.45		100
	121-150 days	—		—		—	3,986		0.56		136
	151-180 days	85,917		0.41		165	—		—		—
	301-330 days	48,941		0.47		317	—		—		—
	Total	$	1,323,080	0.35	%	60	$	1,310,347	0.38	%	49

Offsetting_of_Assets_and_Liabi1

Offsetting of Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Offsetting of Assets and Liabilities [Abstract]
Offsetting of Assets and Liabilities [Table Text Block]	The following tables present information about certain assets and liabilities representing financial instruments as of December 31, 2014 and December 31, 2013. The Company has not previously entered into master netting agreements with any of its counterparties. Certain of the Company's repurchase and reverse repurchase agreements and financial derivative transactions are governed by underlying agreements that generally provide a right of offset in the event of default or in the event of a bankruptcy of either party to the transaction.
	December 31, 2014:
	Description		Amount of Assets (Liabilities) Presented in the Consolidated Balance Sheet(1)			Financial Instruments Available for Offset			Financial Instruments Transferred or Pledged as Collateral(2)(3)		Cash Collateral (Received) Pledged(2)(3)			Net Amount
	(In thousands)
	Assets:
	Financial derivatives–assets		$	3,072		$	(2,722	)	$	—	$	—		$	350
	Reverse repurchase agreements		13,987			(13,987		)	—		—			—
	Liabilities:
	Financial derivatives–liabilities		(8,700		)	2,722			—		5,783			(195		)
	Repurchase agreements		(1,323,080		)	13,987			1,303,360		5,733			—
	-1	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
	-2	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore, the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2014 were $1.39 billion. As of December 31, 2014 total cash collateral on financial derivative assets and financial derivative liabilities excludes $0.5 million and $6.3 million of net excess cash collateral.
	-3	When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above table, the Company has made assumptions in allocating pledged or posted collateral among the various rows.
	December 31, 2013:
	Description		Amount of Assets (Liabilities) Presented in the Consolidated Balance Sheet(1)			Financial Instruments Available for Offset			Financial Instruments Transferred or Pledged as Collateral(2)(3)		Cash Collateral (Received) Pledged(2)(3)			Net Amount
	(In thousands)
	Assets:
	Financial derivatives–assets		$	34,963		$	(1,042	)	$	—	$	(22,360	)	$	11,561
	Liabilities:
	Financial derivatives–liabilities		(1,069		)	1,042			—		26			(1		)
	Repurchase agreements		(1,310,347		)	—			1,295,567		14,780			—
	-1	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
	-2	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2013 were $1.36 billion. As of December 31, 2013 total cash collateral on financial derivative assets and liabilities excludes $0.3 million and $3.1 million, respectively of net excess cash collateral.
	-3	When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above table, the Company has made assumptions in allocating pledged or posted collateral among the various rows.

Earnings_per_Share_Tables

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of Earnings Per Share Reconciliation	The following table presents a reconciliation of the earnings/(losses) and shares used in calculating basic EPS for the years ended December 31, 2014 and 2013, and September 25, 2012 (commencement of operations) to December 31, 2012:
	(In thousands except for share amounts)	Year Ended		Year Ended			September 25, 2012 (commencement of operations) to
		31-Dec-14		31-Dec-13			31-Dec-12
	Numerator:
	Net income (loss)	$	16,168	$	(1,914	)	$	(536	)
	Denominator:
	Basic and diluted weighted average shares outstanding	9,142,736		6,566,656			1,633,378
	Basic and Diluted Earnings Per Share	$	1.77	$	(0.29	)	$	(0.33	)

Capital_Capital_Tables

Capital Capital (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Dividends Declared [Table Text Block]	The below table details cash dividends declared by the Board of Trustees during the year ended December 31, 2014:
		Dividend	Dividend Amount	Declaration Date	Record Date	Payment Date
		Per Share
			(In thousands)
	First Quarter	$0.55	$5,027	12-Mar-14	31-Mar-14	28-Apr-14
	Second Quarter	$0.55	$5,027	17-Jun-14	30-Jun-14	25-Jul-14
	Third Quarter	$0.55	$5,032	11-Sep-14	30-Sep-14	27-Oct-14
	Fourth Quarter	$0.55	$5,032	11-Dec-14	31-Dec-14	26-Jan-15
	The below table details cash dividends declared by the Board of Trustees during the year ended December 31, 2013:
		Dividend	Dividend Amount	Declaration Date	Record Date	Payment Date
		Per Share
			(In thousands)
	Second Quarter	$0.14	$1,279	18-Jun-13	28-Jun-13	26-Jul-13
	Third Quarter	$0.50	$4,569	17-Sep-13	27-Sep-13	25-Oct-13
	Fourth Quarter	$0.50	$4,570	12-Dec-13	31-Dec-13	27-Jan-14

Condensed_Quarterly_Financial_1

Condensed Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Condensed Quarterly Financial Data (Unaudited) [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	Detailed below is unaudited quarterly information for the years ended December 31, 2014 and 2013.
	(In thousands except for per share amounts)		Three Month Period Ended March 31, 2014			Three Month Period Ended June 30, 2014			Three Month Period Ended September 30, 2014			Three Month
												Period Ended
												31-Dec-14
	INTEREST INCOME (EXPENSE)
	Interest income		$	11,959		$	11,575		$	11,484		$	11,806
	Interest expense		(1,155		)	(1,070		)	(1,121		)	(1,165		)
	Total net interest income		10,804			10,505			10,363			10,641
	EXPENSES
	Management fees		592			567			574			552
	Professional fees		139			137			123			587
	Other operating expenses		663			613			597			608
	Total expenses		1,394			1,317			1,294			1,747
	OTHER INCOME (LOSS)
	Net realized gains (losses) on real estate securities and financial derivatives		14,556			25,806			(3,425		)	14,070
	Change in net unrealized gains (losses) on real estate securities and financial derivatives		(21,205		)	(23,944		)	(2,111		)	(24,140		)
	Total other income (loss)		(6,649		)	1,862			(5,536		)	(10,070		)
	NET INCOME (LOSS)		$	2,761		$	11,050		$	3,533		$	(1,176	)
	NET INCOME (LOSS) PER COMMON SHARE:
	Basic and Diluted		$	0.3		$	1.21		$	0.39		$	(0.13	)
	CASH DIVIDENDS PER COMMON SHARE:
	Dividends declared		$	0.55		$	0.55		$	0.55		$	0.55
	(In thousands except for per share amounts)		Three Month Period Ended March 31, 2013			Three Month Period Ended June 30, 2013			Three Month Period Ended September 30, 2013			Three Month
												Period Ended
												31-Dec-13
	INTEREST INCOME (EXPENSE)
	Interest income		$	283		$	4,310		$	11,223		$	12,050
	Interest expense		—			(525		)	(1,248		)	(1,283		)
	Total net interest income		283			3,785			9,975			10,767
	EXPENSES
	Management fees		119			703			644			600
	Professional fees		32			237			200			155
	Other operating expenses		46			421			513			656
	Total expenses		197			1,361			1,357			1,411
	OTHER INCOME (LOSS)
	Net realized gains (losses) on real estate securities and financial derivatives		888			5,370			(19,900		)	(16,504		)
	Change in net unrealized gains (losses) on real estate securities and financial derivatives		155			(17,498		)	18,067			7,024
	Total other income (loss)		1,043			(12,128		)	(1,833		)	(9,480		)
	NET INCOME (LOSS)		$	1,129		$	(9,704	)	$	6,785		$	(124	)
	NET INCOME (LOSS) PER COMMON SHARE:
	Basic and Diluted(1)		$	0.69		$	(1.55	)	$	0.74		$	(0.01	)
	CASH DIVIDENDS PER COMMON SHARE:
	Dividends declared		$	—		$	0.14		$	0.5		$	0.5
	-1	For the year ended December 31, 2013 the sum of EPS for the four quarters of 2013 does not equal EPS as calculated for the entire year (see Note 9) as a result of issuances of common shares, as EPS is calculated using average shares outstanding during the period.

Organization_and_Investment_Ob1

Organization and Investment Objective (Details) (USD $)	3 Months Ended	12 Months Ended		0 Months Ended
	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	1-May-13	Sep. 26, 2012
Organization and Investment Objective [Line Items]
Issuance of shares, Value	$31,500,000		$150,000,000
Required Distribution of Taxable Net Income, Percentage on Annual Basis		90.00%
Intended Distribution of Taxable Net Income, Percentage on Annual Basis		100.00%
Common Stock [Member]
Organization and Investment Objective [Line Items]
Issuance of shares, Value				150,000,000
Proceeds from issuance of common shares				148,500,000
IPO [Member] | Common Stock [Member]
Organization and Investment Objective [Line Items]
Issuance of shares, shares				6,450,000
Share price				$20
Private Placement [Member] | Common Stock [Member]
Organization and Investment Objective [Line Items]
Issuance of shares, shares				1,050,000
Share price				$20
Issuance of shares, Value				$21,000,000	$31,500,000

Significant_Accounting_Policie2

Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Required Distribution of Taxable Net Income, Percentage on Annual Basis	90.00%

Schedule_of_MortgageBacked_Sec

Schedule of Mortgage-Backed Securities (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Mortgage-Backed Securities [Line Items]
Fair Value	$1,393,303		$1,326,036
Residential Mortgage Backed Securities [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	1,306,824		1,310,647
Unamortized Premium (Discount)	53,147		30,711
Amortized Cost	1,370,751		1,352,076
Gross Unrealized Gain	26,195		5,654
Gross Unrealized Losses	-3,643		-31,694
Fair Value	1,393,303		1,326,036
Weighted Average Coupon	3.99%		3.72%
Weighted Average Yield	3.41%		3.38%
Weighted Average Life (Years)	7 years 164 days	[1]	8 years 204 days	[1]
Non-Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	50,668		50,006
Unamortized Premium (Discount)	-20,377		-21,327
Amortized Cost	30,291		28,679
Gross Unrealized Gain	2,896		2,196
Gross Unrealized Losses	-686		-194
Fair Value	32,501		30,681
Weighted Average Coupon	2.29%		2.84%
Weighted Average Yield	10.76%		9.12%
Weighted Average Life (Years)	4 years 354 days	[1]	5 years 197 days	[1]
15-year fixed rate mortgages [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	130,720		179,906
Unamortized Premium (Discount)	6,304		7,153
Amortized Cost	137,024		187,059
Gross Unrealized Gain	1,113		65
Gross Unrealized Losses	-109		-3,252
Fair Value	138,028		183,872
Weighted Average Coupon	3.40%		3.09%
Weighted Average Yield	2.46%		2.52%
Weighted Average Life (Years)	5 years 157 days	[1]	5 years 277 days	[1]
20-year fixed rate mortgages [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	9,764
Unamortized Premium (Discount)	577
Amortized Cost	10,341
Gross Unrealized Gain	227
Gross Unrealized Losses	0
Fair Value	10,568
Weighted Average Coupon	4.00%
Weighted Average Yield	3.04%
Weighted Average Life (Years)	6 years 336 days	[1]
30-year fixed rate mortgages [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	1,042,550		1,029,629
Unamortized Premium (Discount)	61,089		41,565
Amortized Cost	1,103,639		1,071,194
Gross Unrealized Gain	20,379		490
Gross Unrealized Losses	-1,764		-28,111
Fair Value	1,122,254		1,043,573
Weighted Average Coupon	4.09%		3.79%
Weighted Average Yield	3.29%		3.30%
Weighted Average Life (Years)	8 years 175 days	[1]	9 years 292 days	[1]
Adjustable Rate Mortgages | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	41,710		43,525
Unamortized Premium (Discount)	2,813		2,647
Amortized Cost	44,523		46,172
Gross Unrealized Gain	90		46
Gross Unrealized Losses	-330		-103
Fair Value	44,283		46,115
Weighted Average Coupon	4.60%		4.72%
Weighted Average Yield	3.08%		3.24%
Weighted Average Life (Years)	5 years 354 days	[1]	3 years 288 days	[1]
Reverse mortgages [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	31,412		7,581
Unamortized Premium (Discount)	2,741		673
Amortized Cost	34,153		8,254
Gross Unrealized Gain	300		16
Gross Unrealized Losses	-28		-2
Fair Value	34,425		8,268
Weighted Average Coupon	4.91%		4.85%
Weighted Average Yield	2.56%		2.90%
Weighted Average Life (Years)	4 years 270 days	[1]	3 years 150 days	[1]
Interest-Only [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Amortized Cost	10,780		10,718
Gross Unrealized Gain	1,190		2,841
Gross Unrealized Losses	-726		-32
Fair Value	11,244		13,527
Weighted Average Coupon	4.04%		3.97%
Weighted Average Yield	11.82%		11.79%
Weighted Average Life (Years)	2 years 248 days	[1]	5 years 7 days	[1]
Agency Securities [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Current Principal	1,256,156		1,260,641
Unamortized Premium (Discount)	73,524		52,038
Amortized Cost	1,340,460		1,323,397
Gross Unrealized Gain	23,299		3,458
Gross Unrealized Losses	-2,957		-31,500
Fair Value	$1,360,802		$1,295,355
Weighted Average Coupon	4.05%		3.75%
Weighted Average Yield	3.24%		3.26%
Weighted Average Life (Years)	7 years 197 days	[1]	8 years 245 days	[1]
[1]	Average lives of RMBS are generally shorter than stated contractual maturities. Average lives are affected by the contractual maturities of the underlying mortgages, scheduled periodic payments of principal, and unscheduled prepayments of principal.

Schedule_of_MortgageBacked_Sec1

Schedule of Mortgage-Backed Securities by Weighted Average Life (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	$1,393,303	$1,326,036
Non-Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	32,501	30,681
Amortized Cost	30,291	28,679
Weighted Average Coupon Rate, Percent	2.29%	2.84%
Less than three years [Member] | Non-Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	2,837	1,715
Amortized Cost	1,785	1,216
Weighted Average Coupon Rate, Percent	3.02%	2.38%
Greater than three years and less than seven years [Member] | Non-Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	17,660	16,488
Amortized Cost	17,662	15,950
Weighted Average Coupon Rate, Percent	2.63%	3.42%
Greater than seven years and less than eleven years [Member] | Non-Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	12,004	11,656
Amortized Cost	10,844	10,708
Weighted Average Coupon Rate, Percent	1.28%	1.43%
Greater than eleven years [Member] | Non-Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value		822
Amortized Cost		805
Weighted Average Coupon Rate, Percent		7.69%
Fixed Rate [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	1,349,558	1,281,828
Amortized Cost	1,329,680	1,312,679
Weighted Average Coupon Rate, Percent	4.05%	3.73%
Fixed Rate [Member] | Less than three years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	18,428	5,554
Amortized Cost	18,418	5,518
Weighted Average Coupon Rate, Percent	5.13%	5.68%
Fixed Rate [Member] | Greater than three years and less than seven years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	410,759	243,120
Amortized Cost	405,739	246,342
Weighted Average Coupon Rate, Percent	4.12%	3.48%
Fixed Rate [Member] | Greater than seven years and less than eleven years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	920,371	1,031,552
Amortized Cost	905,523	1,059,223
Weighted Average Coupon Rate, Percent	4.00%	3.79%
Fixed Rate [Member] | Greater than eleven years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value		1,602
Amortized Cost		1,596
Weighted Average Coupon Rate, Percent		4.50%
Interest-Only [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	11,244	13,527
Amortized Cost	10,780	10,718
Weighted Average Coupon Rate, Percent	4.04%	3.97%
Interest-Only [Member] | Less than three years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	5,197	955
Amortized Cost	5,563	762
Weighted Average Coupon Rate, Percent	3.42%	6.48%
Interest-Only [Member] | Greater than three years and less than seven years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	6,047	7,643
Amortized Cost	5,217	6,198
Weighted Average Coupon Rate, Percent	5.19%	3.31%
Interest-Only [Member] | Greater than seven years and less than eleven years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value	0	4,929
Amortized Cost	0	3,758
Weighted Average Coupon Rate, Percent	0.00%	4.91%
Interest-Only [Member] | Greater than eleven years [Member] | Agency RMBS [Member]
Mortgage-Backed Securities [Line Items]
Mortgage-backed securities, at fair value		0
Amortized Cost		$0
Weighted Average Coupon Rate, Percent		0.00%

MortgageBacked_Securities_Inte

Mortgage-Backed Securities Interest Income Components (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Interest Income Components [Line Items]
Amortization of premiums and accretion of discounts (net)	$114	($7,174)	($3,911)
Agency RMBS [Member]
Interest Income Components [Line Items]
Coupon Income	0	52,755	30,504
Amortization of premiums and accretion of discounts (net)	0	-9,112	-4,863
Interest Income	0	43,643	25,641
Non-Agency RMBS [Member]
Interest Income Components [Line Items]
Coupon Income	125	1,237	1,185
Amortization of premiums and accretion of discounts (net)	114	1,930	952
Interest Income	239	3,167	2,137
Residential Mortgage Backed Securities [Member]
Interest Income Components [Line Items]
Coupon Income	125	53,992	31,689
Amortization of premiums and accretion of discounts (net)	114	-7,182	-3,911
Interest Income	$239	$46,810	$27,778

MortgageBacked_Securities_Narr

Mortgage-Backed Securities Narrative (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Weighted Average Holdings	$1,363	$879.90

Valuation_Schedule_of_Fair_Val

Valuation Schedule of Fair Value Measurements (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	$1,393,303,000		$1,326,036,000
Financial derivatives-assets, at fair value	3,072,000	[1]	34,963,000	[1]
Reverse repurchase agreements	13,987,000	[1]	0
U.S. Treasury securities sold short, at fair value	-13,959,000		0
Financial derivatives-liabilities, at fair value	-8,700,000	[1]	-1,069,000	[1]
Fair Value, Transfers between Level 1 and Level 2, Amount	0
Fair Value Level 1 To Level 2 To Level 3 Transfers Amount			0
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Financial derivatives-assets, at fair value	0		0
Reverse repurchase agreements	0
Total mortgage-backed securities, financial derivatives–assets, and reverse repurchase agreements, at fair value	0		0
Financial derivatives-liabilities, at fair value	0		0
Total U.S. Treasury securities and financial derivatives-liabilities, at fair value	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	1,371,977,000		1,281,828,000
Financial derivatives-assets, at fair value	3,072,000		34,963,000
Reverse repurchase agreements	13,987,000
Total mortgage-backed securities, financial derivatives–assets, and reverse repurchase agreements, at fair value	1,389,036,000		1,316,791,000
Financial derivatives-liabilities, at fair value	-8,700,000		-1,069,000
Total U.S. Treasury securities and financial derivatives-liabilities, at fair value	-22,659,000
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	21,326,000		44,208,000
Financial derivatives-assets, at fair value	0		0
Reverse repurchase agreements	0
Total mortgage-backed securities, financial derivatives–assets, and reverse repurchase agreements, at fair value	21,326,000		44,208,000
Financial derivatives-liabilities, at fair value	0		0
Total U.S. Treasury securities and financial derivatives-liabilities, at fair value	0
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	1,393,303,000		1,326,036,000
Financial derivatives-assets, at fair value	3,072,000		34,963,000
Reverse repurchase agreements	13,987,000
Total mortgage-backed securities, financial derivatives–assets, and reverse repurchase agreements, at fair value	1,410,362,000		1,360,999,000
Financial derivatives-liabilities, at fair value	-8,700,000		-1,069,000
Total U.S. Treasury securities and financial derivatives-liabilities, at fair value	-22,659,000
Non-Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	32,501,000		30,681,000
Non-Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Non-Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	22,419,000		0
Non-Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	10,082,000		30,681,000
Non-Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	32,501,000		30,681,000
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	1,393,303,000		1,326,036,000
US Treasury Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities sold short, at fair value	0
US Treasury Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities sold short, at fair value	-13,959,000
US Treasury Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities sold short, at fair value	0
US Treasury Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Treasury securities sold short, at fair value	-13,959,000
15-year fixed rate mortgages [Member] | Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	138,028,000		183,872,000
15-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
15-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	138,028,000		183,872,000
15-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
15-year fixed rate mortgages [Member] | Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	138,028,000		183,872,000
20-year fixed rate mortgages [Member] | Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	10,568,000
20-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0
20-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	10,568,000
20-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0
20-year fixed rate mortgages [Member] | Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	10,568,000
30-year fixed rate mortgages [Member] | Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	1,122,254,000		1,043,573,000
30-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
30-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	1,122,254,000		1,043,573,000
30-year fixed rate mortgages [Member] | Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
30-year fixed rate mortgages [Member] | Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	1,122,254,000		1,043,573,000
Adjustable Rate Mortgages | Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	44,283,000		46,115,000
Adjustable Rate Mortgages | Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Adjustable Rate Mortgages | Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	44,283,000		46,115,000
Adjustable Rate Mortgages | Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Adjustable Rate Mortgages | Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	44,283,000		46,115,000
Reverse mortgages [Member] | Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	34,425,000		8,268,000
Reverse mortgages [Member] | Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Reverse mortgages [Member] | Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	34,425,000		8,268,000
Reverse mortgages [Member] | Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Reverse mortgages [Member] | Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	34,425,000		8,268,000
Interest-Only [Member] | Agency RMBS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	11,244,000		13,527,000
Interest-Only [Member] | Agency RMBS [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Interest-Only [Member] | Agency RMBS [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	0		0
Interest-Only [Member] | Agency RMBS [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	11,244,000		13,527,000
Interest-Only [Member] | Agency RMBS [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities, at fair value	11,244,000		13,527,000
Interest Rate Swap [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	0		0
Financial derivatives-liabilities, at fair value	0		0
Interest Rate Swap [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	2,518,000		32,700,000
Financial derivatives-liabilities, at fair value	-7,026,000		-956,000
Interest Rate Swap [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	0		0
Financial derivatives-liabilities, at fair value	0		0
Interest Rate Swap [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	2,518,000		32,700,000
Financial derivatives-liabilities, at fair value	-7,026,000		-956,000
Interest Rate Swap [Member] | Derivative Financial Instruments, Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	2,518,000		32,700,000
Interest Rate Swap [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-liabilities, at fair value	-7,026,000		-956,000
Interest Rate Swaption [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	0
Financial derivatives-liabilities, at fair value			0
Interest Rate Swaption [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	78,000
Financial derivatives-liabilities, at fair value			-85,000
Interest Rate Swaption [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	0
Financial derivatives-liabilities, at fair value			0
Interest Rate Swaption [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	78,000
Financial derivatives-liabilities, at fair value			-85,000
Interest Rate Swaption [Member] | Derivative Financial Instruments, Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	78,000		0
Interest Rate Swaption [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-liabilities, at fair value	0		-85,000
TBA securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	0		0
Financial derivatives-liabilities, at fair value	0		0
TBA securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	476,000		2,263,000
Financial derivatives-liabilities, at fair value	-1,674,000		-28,000
TBA securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	0		0
Financial derivatives-liabilities, at fair value	0		0
TBA securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial derivatives-assets, at fair value	476,000		2,263,000
Financial derivatives-liabilities, at fair value	($1,674,000)		($28,000)
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.

Valuation_Unobservable_Input_R

Valuation Unobservable Input Reconciliation (Details) (Level 3 [Member], USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Agency RMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		$13,527	$0
Purchases		4,853	12,167
Proceeds from sales		-2,330	0
Principal repayments		0	0
(Amortization)/accretion, net		-3,136	-1,449
Net realized gains		676	0
Change in net unrealized gains (losses)		-2,346	2,809
Transfers
Transfers out of level 3		0	0
Transfers into level 3		0	0
Ending balance		11,244	13,527
Change in net unrealized gains (losses) for level 3 assets still held		-2,000	2,800
Non-Agency RMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0	30,681	13,596
Purchases	13,643	14,712	41,734
Proceeds from sales	-248	-11,104	-23,007
Principal repayments	0	-5,443	-5,923
(Amortization)/accretion, net	114	1,930	952
Net realized gains	-19	1,518	1,433
Change in net unrealized gains (losses)	106	207	1,896
Transfers
Transfers out of level 3	0	-22,419	0
Transfers into level 3	0	0	0
Ending balance	13,596	10,082	30,681
Change in net unrealized gains (losses) for level 3 assets still held	$100	$700	$2,000

Valuation_Qualtitative_Informa

Valuation Qualtitative Information (Details) (Level 3 [Member], USD $)	Dec. 31, 2014		Dec. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	$21,326,000		$44,208,000
Non-Agency RMBS [Member] | Market Quotes [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	7,819,000		27,422,000
Non-Agency RMBS [Member] | Market Quotes [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non-Binding Third-Party Valuation	21.38		20
Non-Agency RMBS [Member] | Market Quotes [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non-Binding Third-Party Valuation	84.91		100.25
Non-Agency RMBS [Member] | Market Quotes [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non-Binding Third-Party Valuation	54.11	[1]	75.39	[1]
Non-Agency RMBS [Member] | Discounted Cash Flows [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	2,263,000		3,259,000
Non-Agency RMBS [Member] | Discounted Cash Flows [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	6.30%		6.00%
Projected Collateral Prepayments	35.90%		12.20%
Projected Collateral Losses	7.50%		6.40%
Projected Collateral Recoveries	11.00%		4.60%
Projected Collateral Scheduled Amortization	45.60%		29.90%
Non-Agency RMBS [Member] | Discounted Cash Flows [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	6.30%		17.00%
Projected Collateral Prepayments	35.90%		58.10%
Projected Collateral Losses	7.50%		26.50%
Projected Collateral Recoveries	11.00%		12.80%
Projected Collateral Scheduled Amortization	45.60%		54.90%
Non-Agency RMBS [Member] | Discounted Cash Flows [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield	6.30%	[1]	11.90%	[1]
Projected Collateral Prepayments	35.90%	[1]	33.90%	[1]
Projected Collateral Losses	7.50%	[1]	11.80%	[1]
Projected Collateral Recoveries	11.00%	[1]	8.80%	[1]
Projected Collateral Scheduled Amortization	45.60%	[1]	45.50%	[1]
Projected Total	100.00%	[1]	100.00%	[1]
Interest-Only [Member] | Agency RMBS [Member] | Market Quotes [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	7,006,000		12,368,000
Interest-Only [Member] | Agency RMBS [Member] | Market Quotes [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non-Binding Third-Party Valuation	4.74		4.99
Interest-Only [Member] | Agency RMBS [Member] | Market Quotes [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non-Binding Third-Party Valuation	20.38		22.47
Interest-Only [Member] | Agency RMBS [Member] | Market Quotes [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Non-Binding Third-Party Valuation	13.35	[1]	14.92	[1]
Interest-Only [Member] | Agency RMBS [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value	$4,238,000		$1,159,000
Interest-Only [Member] | Agency RMBS [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	63.30%		57.80%
Projected Collateral Scheduled Amortization	7.70%		42.20%
FairValueInputsLiborOas	0.83%	[2]	4.36%	[2]
Interest-Only [Member] | Agency RMBS [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	92.30%		57.80%
Projected Collateral Scheduled Amortization	36.70%		42.20%
FairValueInputsLiborOas	19.52%	[2]	4.36%	[2]
Interest-Only [Member] | Agency RMBS [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Projected Collateral Prepayments	75.20%	[1]	57.80%	[1]
Projected Collateral Scheduled Amortization	24.80%	[1]	42.20%	[1]
Projected Total	100.00%	[1]	100.00%	[1]
FairValueInputsLiborOas	4.90%	[1],[2]	4.36%	[1],[2]
[1]	Averages are weighted based on the fair value of the related instrument.
[2]	Shown in basis points.

Derivative_Instruments_Schedul

Derivative Instruments Schedule of Derivatves (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative [Line Items]
Financial derivatives–assets, at fair value	$3,072	[1]	$34,963	[1]
Financial derivatives-liabilities, at fair value	-8,700	[1]	-1,069	[1]
Derivative, Fair Value, Net	-5,628		33,894
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	-4,508		31,744
TBA securities- sale contracts [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	-1,580	[2]	2,234	[2]
TBA securities- purchase contracts [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	382	[2]	1	[2]
TBA securities [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	-1,198	[2]	2,235	[2]
Derivative Financial Instruments, Assets [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Financial derivatives–assets, at fair value	2,518		32,700
Derivative Financial Instruments, Assets [Member] | TBA securities- sale contracts [Member]
Derivative [Line Items]
Financial derivatives–assets, at fair value	89	[2]	2,262	[2]
Derivative Financial Instruments, Assets [Member] | TBA securities- purchase contracts [Member]
Derivative [Line Items]
Financial derivatives–assets, at fair value	387	[2]	1	[2]
Derivative Financial Instruments, Assets [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Financial derivatives–assets, at fair value	78		0
Derivative Financial Instruments, Liabilities [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Financial derivatives-liabilities, at fair value	-7,026		-956
Derivative Financial Instruments, Liabilities [Member] | TBA securities- sale contracts [Member]
Derivative [Line Items]
Financial derivatives-liabilities, at fair value	-1,669	[2]	-28	[2]
Derivative Financial Instruments, Liabilities [Member] | TBA securities- purchase contracts [Member]
Derivative [Line Items]
Financial derivatives-liabilities, at fair value	-5	[2]	0	[2]
Derivative Financial Instruments, Liabilities [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Financial derivatives-liabilities, at fair value	$0		($85)
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
[2]	Net carrying value represents the difference between the market value of the TBA contract as of period end and the cost basis and is reported in Financial derivatives-assets at fair value and Financial derivatives-liabilities at fair value on the Consolidated Balance Sheet.

Derivative_Instruments_Schedul1

Derivative Instruments Schedule of Interest Rate Swaps by Maturity (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative, Fair Value, Net	($5,628)	$33,894
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	424,820	748,350
Derivative, Fair Value, Net	-4,508	31,744
Weighted Average Pay Rate	1.87%	1.67%
Weighted Average Receive Rate	0.23%	0.24%
Weighted Average Years to Maturity	8 years 204 days	8 years 51 days
Year 2016 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	48,000	48,000
Derivative, Fair Value, Net	-91	-171
Weighted Average Pay Rate	0.80%	0.80%
Weighted Average Receive Rate	0.23%	0.24%
Weighted Average Years to Maturity	1 year 281 days	2 years 281 days
Year 2017 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	74,750	124,000
Derivative, Fair Value, Net	-388	-517
Weighted Average Pay Rate	1.21%	1.19%
Weighted Average Receive Rate	0.24%	0.24%
Weighted Average Years to Maturity	2 years 215 days	3 years 223 days
Year 2018 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	10,000	156,500
Derivative, Fair Value, Net	167	2,784
Weighted Average Pay Rate	0.84%	1.19%
Weighted Average Receive Rate	0.23%	0.24%
Weighted Average Years to Maturity	3 years 120 days	4 years 230 days
Year 2020 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	23,500	137,100
Derivative, Fair Value, Net	471	6,444
Weighted Average Pay Rate	1.42%	1.49%
Weighted Average Receive Rate	0.23%	0.24%
Weighted Average Years to Maturity	5 years 139 days	6 years 22 days
Year 2023 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	209,350	218,000
Derivative, Fair Value, Net	140	14,599
Weighted Average Pay Rate	2.13%	2.16%
Weighted Average Receive Rate	0.23%	0.24%
Weighted Average Years to Maturity	8 years 146 days	9 years 150 days
Year 2024 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	12,900
Derivative, Fair Value, Net	-605
Weighted Average Pay Rate	2.73%
Weighted Average Receive Rate	0.23%
Weighted Average Years to Maturity	9 years 164 days
Year 2043 [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative notional	46,320	64,750
Derivative, Fair Value, Net	($4,202)	$8,605
Weighted Average Pay Rate	3.12%	3.18%
Weighted Average Receive Rate	0.23%	0.24%
Weighted Average Years to Maturity	28 years 153 days	29 years 161 days

Derivative_Instruments_Schedul2

Derivative Instruments Schedule of Swaptions (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivative [Line Items]
Financial derivatives-liabilities, at fair value	($8,700)	[1]	($1,069)	[1]
Fixed Payer [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Financial derivatives-liabilities, at fair value			-59
Fixed Pay Rate on Derivatives			3.31%
Maturity term of asset underlying derivative contract			10 years
Derivative notional			22,000
Derivative, Remaining Maturity			8 months 27 days
Straddle [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Financial derivatives-liabilities, at fair value	78		-26
Fixed Pay Rate on Derivatives	3.00%		3.08%
Maturity term of asset underlying derivative contract	10 years		10 years
Derivative notional	$9,700		$8,000
Derivative, Remaining Maturity	6 months 16 days		9 months 27 days
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.

Derivative_Instruments_Schedul3

Derivative Instruments Schedule of TBA Securities (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative [Line Items]
Financial derivatives–assets, at fair value	$3,072	[1]	$34,963	[1]
Financial derivatives-liabilities, at fair value	-8,700	[1]	-1,069	[1]
Derivative, Fair Value, Net	-5,628		33,894
TBA securities- purchase contracts [Member]
Derivative [Line Items]
Derivative notional	68,319	[2]	1,600	[2]
Derivative cost basis	70,360	[3]	1,725	[3]
Market Value, Underyling	70,742	[4]	1,726	[4]
Derivative, Fair Value, Net	382	[5]	1	[5]
TBA securities- sale contracts [Member]
Derivative [Line Items]
Derivative notional	-605,076	[2]	-379,478	[2]
Derivative cost basis	-644,949	[3]	-393,042	[3]
Market Value, Underyling	-646,529	[4]	-390,808	[4]
Derivative, Fair Value, Net	-1,580	[5]	2,234	[5]
TBA securities [Member]
Derivative [Line Items]
Derivative notional, net	-536,757	[2]	-377,878	[2]
Derivative cost basis	-574,589	[3]	-391,317	[3]
Market Value, Underyling	-575,787	[4]	-389,082	[4]
Derivative, Fair Value, Net	-1,198	[5]	2,235	[5]
Derivative Financial Instruments, Assets [Member] | TBA securities- purchase contracts [Member]
Derivative [Line Items]
Derivative notional	53,319	[2]	1,600	[2]
Derivative cost basis	54,757	[3]	1,725	[3]
Market Value, Underyling	55,144	[4]	1,726	[4]
Financial derivatives–assets, at fair value	387	[5]	1	[5]
Derivative Financial Instruments, Assets [Member] | TBA securities- sale contracts [Member]
Derivative [Line Items]
Derivative notional	-79,090	[2]	-363,078	[2]
Derivative cost basis	-85,730	[3]	-375,524	[3]
Market Value, Underyling	-85,641	[4]	-373,262	[4]
Financial derivatives–assets, at fair value	89	[5]	2,262	[5]
Derivative Financial Instruments, Liabilities [Member] | TBA securities- purchase contracts [Member]
Derivative [Line Items]
Derivative notional	15,000	[2]	0	[2]
Derivative cost basis	15,603	[3]	0	[3]
Market Value, Underyling	15,598	[4]	0	[4]
Financial derivatives-liabilities, at fair value	-5	[5]	0	[5]
Derivative Financial Instruments, Liabilities [Member] | TBA securities- sale contracts [Member]
Derivative [Line Items]
Derivative notional	-525,986	[2]	-16,400	[2]
Derivative cost basis	-559,219	[3]	-17,518	[3]
Market Value, Underyling	-560,888	[4]	-17,546	[4]
Financial derivatives-liabilities, at fair value	($1,669)	[5]	($28)	[5]
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
[2]	Notional amount represents the principal balance of the underlying Agency RMBS.
[3]	Cost basis represents the forward price to be paid for the underlying Agency RMBS.
[4]	Market value represents the current market value of the underlying Agency RMBS (on a forward delivery basis) as of period end.
[5]	Net carrying value represents the difference between the market value of the TBA contract as of period end and the cost basis and is reported in Financial derivatives-assets at fair value and Financial derivatives-liabilities at fair value on the Consolidated Balance Sheet.

Schedule_of_Derivative_Activit

Schedule of Derivative Activity (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Interest Rate Swap [Member]
Derivative [Line Items]
Financial derivative average monthly notional	$566,379	$609,310
TBA securities [Member]
Derivative [Line Items]
Financial derivative average monthly notional	545,646	364,943
Interest Rate Swaption [Member]
Derivative [Line Items]
Financial derivative average monthly notional	$20,631	$11,200

Derivative_Instruments_Schedul4

Derivative Instruments Schedule of Gains and Losses on Derivative Instruments (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Net realized gains (losses) on periodic settements of interest rate swaps		($9,217)	($5,200)
Net realized gains (losses) other than on periodic settements of interest rate swaps		-22,661	12,510
Net realized gains (losses) on financial derivatives	0	-31,878	7,310
Change in net unrealized gains (losses) on accrued periodic settlements on interest rate swaps		410	-1,538
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		-39,932	35,432
Change in net unrealized gains (losses) on financial derivatives	0	-39,522	33,894
Interest Rate Swap [Member]
Derivative [Line Items]
Net realized gains (losses) on periodic settements of interest rate swaps		-9,217	-5,200
Net realized gains (losses) other than on periodic settements of interest rate swaps		1,823	5,060
Net realized gains (losses) on financial derivatives		-7,394	-140
Change in net unrealized gains (losses) on accrued periodic settlements on interest rate swaps		410	-1,538
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		-36,662	33,282
Change in net unrealized gains (losses) on financial derivatives		-36,252	31,744
Interest Rate Swaption [Member]
Derivative [Line Items]
Net realized gains (losses) other than on periodic settements of interest rate swaps		-935	0
Net realized gains (losses) on financial derivatives		-935	0
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		163	-85
Change in net unrealized gains (losses) on financial derivatives		163	-85
TBA securities [Member]
Derivative [Line Items]
Net realized gains (losses) other than on periodic settements of interest rate swaps		-23,568	7,450
Net realized gains (losses) on financial derivatives		-23,568	7,450
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		-3,433	2,235
Change in net unrealized gains (losses) on financial derivatives		-3,433	2,235
Future [Member]
Derivative [Line Items]
Net realized gains (losses) other than on periodic settements of interest rate swaps		19
Net realized gains (losses) on financial derivatives		19
Change in Net Unrealized Gains (Losses) Other Than on Accrued Periodic Settlements of Interest Rate Swaps		0
Change in net unrealized gains (losses) on financial derivatives		$0

Financial_Derivatives_Narrativ

Financial Derivatives Narrative (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
U.S. Treasury securities sold short, at fair value	$13,959,000	$0
US Treasury Securities [Member]
Derivative [Line Items]
U.S. Treasury securities sold short, at fair value	13,959,000
Investment Sold, Not yet Purchased, Balance, Principal Amount	$13,900,000

Borrowings_under_Repurchase_Ag2

Borrowings under Repurchase Agreements Schedule of Repurchase Agreements by Maturity (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Repurchase Agreements [Line Items]
Repurchase agreements	$1,323,080	[1]	$1,310,347	[1]
Debt, Weighted Average Interest Rate	0.35%		0.38%
Repurchase Agreement Weighted Average Maturity Of Agreements	60 days		49 days
Maturity up to 30 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	437,633		338,700
Debt, Weighted Average Interest Rate	0.33%		0.35%
Repurchase Agreement Weighted Average Maturity Of Agreements	15 days		14 days
Maturity 31 to 60 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	417,009		531,799
Debt, Weighted Average Interest Rate	0.34%		0.39%
Repurchase Agreement Weighted Average Maturity Of Agreements	44 days		46 days
Maturity 61 to 90 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	333,580		326,386
Debt, Weighted Average Interest Rate	0.36%		0.38%
Repurchase Agreement Weighted Average Maturity Of Agreements	72 days		72 days
Maturity 91 to 120 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	0		109,476
Debt, Weighted Average Interest Rate	0.00%		0.45%
Repurchase Agreement Weighted Average Maturity Of Agreements	0 days		100 days
Maturity 121 to 150 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	0		3,986
Debt, Weighted Average Interest Rate	0.00%		0.56%
Repurchase Agreement Weighted Average Maturity Of Agreements	0 days		136 days
Matuirty 151 to 180 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	85,917		0
Debt, Weighted Average Interest Rate	0.41%		0.00%
Repurchase Agreement Weighted Average Maturity Of Agreements	165 days		0 days
Maturity 301 to 330 days [Member]
Repurchase Agreements [Line Items]
Repurchase agreements	$48,941		$0
Debt, Weighted Average Interest Rate	0.47%		0.00%
Repurchase Agreement Weighted Average Maturity Of Agreements	317 days		0 days
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.

Borrowings_under_Repurchase_Ag3

Borrowings under Repurchase Agreements (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
			counterparties
Repurchase Agreements [Line Items]
Number of Counterparties with Outstanding Repurchase Agreements	10		9
Repurchase Agreements, collateral amount	1,400,000,000		$1,400,000,000
Pledged Assets, Unsettled	41,800,000		76,100,000
Minimum [Member]
Repurchase Agreements [Line Items]
Repurchase Agreements Maturity	30 days
Maximum [Member]
Repurchase Agreements [Line Items]
Repurchase Agreements Maturity	180 days
Repurchase Agreements [Member]
Repurchase Agreements [Line Items]
Cash Collateral (Received) Pledged	5,733,000	[1],[2]	14,780,000	[1],[3]
Security Owned and Pledged as Collateral, Fair Value	2,100,000		3,500,000
Securities Held as Collateral, at Fair Value	400,000		$500,000
[1]	When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above table, the Company has made assumptions in allocating pledged or posted collateral among the various rows.
[2]	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore, the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2014 were $1.39 billion. As of December 31, 2014 total cash collateral on financial derivative assets and financial derivative liabilities excludes $0.5 million and $6.3 million of net excess cash collateral.
[3]	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2013 were $1.36 billion. As of December 31, 2013 total cash collateral on financial derivative assets and liabilities excludes $0.3 million and $3.1 million, respectively of net excess cash collateral.

Offsetting_of_Assets_and_Liabi2

Offsetting of Assets and Liabilities (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Offsetting Assets and Liabilities [Line Items]
Securities Collateral Relating To Repurchase Agreements	$1,390,000,000		$1,360,000,000
Financial derivatives–assets, at fair value	3,072,000	[1]	34,963,000	[1]
Derivative Liability, Fair Value, Amount Offset Against Collateral	-2,722,000		-1,042,000
Reverse repurchase agreements	13,987,000	[1]	0
Securities sold under agreements to repurchase available for offset	-13,987,000
Financial derivatives-liabilities, at fair value	-8,700,000	[1]	-1,069,000	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,722,000		1,042,000
Repurchase agreements	-1,323,080,000	[1]	-1,310,347,000	[1]
Securities purchased under agreements to resell available for offset	13,987,000		0
Derivative Financial Instruments, Assets [Member]
Offsetting Assets and Liabilities [Line Items]
Derivatives and related collateral, net	350,000		11,561,000
Financial Instruments Pledged as Collateral	0	[2],[3]	0	[2],[4]
Cash Collateral (Received) Pledged	0	[2],[3]	-22,360,000	[2],[4]
Excess cash collateral	500,000		300,000
Reverse Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Financial Instruments Pledged as Collateral	0	[2],[3]
Cash Collateral (Received) Pledged	0	[2],[3]
Reverse Repurchase Agreements and Related Collateral Net	0
Derivative Financial Instruments, Liabilities [Member]
Offsetting Assets and Liabilities [Line Items]
Derivatives and related collateral, net	-195,000		-1,000
Financial Instruments Pledged as Collateral	0	[2],[3]	0	[2],[4]
Cash Collateral (Received) Pledged	5,783,000	[2],[3]	26,000	[2],[4]
Excess cash collateral	6,300,000		3,100,000
Repurchase Agreements [Member]
Offsetting Assets and Liabilities [Line Items]
Repurchse agreements and related collateral, net	0		0
Financial Instruments Pledged as Collateral	1,303,360,000	[2],[3]	1,295,567,000	[2],[4]
Cash Collateral (Received) Pledged	$5,733,000	[2],[3]	$14,780,000	[2],[4]
[1]	In the Company's Consolidated Balance Sheet, all balances associated with the repurchase agreements and financial derivatives are presented on a gross basis.
[2]	When collateral is pledged to or pledged by a counterparty, it is often pledged or posted with respect to all positions with such counterparty, and in such cases such collateral cannot be specifically identified as relating to a specific asset or liability. As a result, in preparing the above table, the Company has made assumptions in allocating pledged or posted collateral among the various rows.
[3]	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore, the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2014 were $1.39 billion. As of December 31, 2014 total cash collateral on financial derivative assets and financial derivative liabilities excludes $0.5 million and $6.3 million of net excess cash collateral.
[4]	For the purpose of this presentation, for each row the total amount of financial instruments transferred or pledged and cash collateral (received) or pledged may not exceed the applicable gross amount of assets or (liabilities) as presented here. Therefore the Company has reduced the amount of financial instruments transferred or pledged as collateral related to the Company's repurchase agreements and cash collateral pledged on the Company's financial derivative assets and liabilities. Total financial instruments transferred or pledged as collateral on the Company's repurchase agreements as of December 31, 2013 were $1.36 billion. As of December 31, 2013 total cash collateral on financial derivative assets and liabilities excludes $0.3 million and $3.1 million, respectively of net excess cash collateral.

Management_Fees_Details

Management Fees (Details) (USD $)	3 Months Ended									12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Management Fees Disclosure [Abstract]
Annual base management fee percentage	1.50%									1.50%
Management fees	$552	$574	$567	$592	$600	$644	$703	$119	$124	$2,285	$2,066

Earnings_per_Share_Details

Earnings per Share (Details) (USD $)	3 Months Ended													12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income (loss)	($1,176)	$3,533	$11,050	$2,761	($124)		$6,785		($9,704)		$1,129		($536)	$16,168	($1,914)
Basic and diluted weighted average shares outstanding													1,633,378	9,142,736	6,566,656
Basic and Diluted Earnings Per Share (in dollars per share)	($0.13)	$0.39	$1.21	$0.30	($0.01)	[1]	$0.74	[1]	($1.55)	[1]	$0.69	[1]	($0.33)	$1.77	($0.29)
[1]	For the year ended December 31, 2013 the sum of EPS for the four quarters of 2013 does not equal EPS as calculated for the entire year (see Note 9) as a result of issuances of common shares, as EPS is calculated using average shares outstanding during the period.

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Related Party Transactions [Abstract]
Management agreement renewal period	1 year
Expense reimbursement period	60 days
Expenses Reimbursed to Related Party	$2.30	$2.10
Termination fee percentage	5.00%

Capital_Details

Capital (Details) (USD $)	0 Months Ended		3 Months Ended		12 Months Ended		17 Months Ended	0 Months Ended
	Aug. 13, 2013	Apr. 18, 2013	Dec. 31, 2012		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	1-May-13	Sep. 26, 2012	Sep. 11, 2014	Sep. 23, 2013
Equity [Line Items]
Common stock authorized					500,000,000	500,000,000	500,000,000
Common stock par value					$0.01	$0.01	$0.01
Preferred stock authorized					100,000,000	100,000,000	100,000,000
Preferred stock par value					$0.01	$0.01	$0.01
Common stock, shares issued					9,149,274	9,139,842	9,149,274
Common stock outstanding					9,149,274	9,139,842	9,149,274
Preferred shares issued					0	0	0
Issuance of shares, Value			$31,500,000			$150,000,000
Stock Dividend, Percent		3.71%
Stock Dividend, Shares		58,378
Dividend per share		$20.38
Stock Repurchase Program, Authorized Amount	10,000,000
Repurchase of shares, Shares							0
Intended Distribution of Taxable Net Income, Percentage on Annual Basis					100.00%
Common Shares [Member]
Equity [Line Items]
Issuance of shares, Value								150,000,000
Proceeds from issuance of common shares								148,500,000
Common Shares [Member] | IPO [Member]
Equity [Line Items]
Issuance of shares, shares								6,450,000
Share price								$20
Common Shares [Member] | Private Placement [Member]
Equity [Line Items]
Issuance of shares, shares								1,050,000
Share price								$20
Issuance of shares, Value								21,000,000	31,500,000
Common Shares [Member]
Equity [Line Items]
Issuance of restricted shares, shares					9,432	6,464				9,432	6,464
Issuance of shares, shares			1,575,000			7,500,000
Issuance of shares, Value			$16,000			$75,000
Stock Dividend, Shares			58,378	[1]
Repurchase of shares, Shares			-100
Unvested shares [Member] | Common Shares [Member]
Equity [Line Items]
Issuance of restricted shares, shares										6,912
Vested shares [Member] | Common Shares [Member]
Equity [Line Items]
Issuance of restricted shares, shares										2,520
[1]	Stock dividend was declared on April 18, 2013 and was retrospectively applied.

Capital_Schedule_of_Dividends_

Capital Schedule of Dividends Declared (Details) (USD $)

0 Months Ended

3 Months Ended

12 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Mar. 10, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Equity [Abstract]

Dividends declared (in dollars per share)

$0.55

$0.55

$0.55

$0.55

$0.55

$0.50

$0.50

$0.14

$0

$0

$2.20

$1.14

Dividends

$5,032

$5,032

$5,027

$5,027

$4,570

$4,569

$1,279

($20,118)

($10,418)

Dividends Payable, Date Declared

11-Mar-15

11-Dec-14

11-Sep-14

17-Jun-14

12-Mar-14

12-Dec-13

17-Sep-13

18-Jun-13

Dividends Payable, Date of Record

31-Mar-15

31-Dec-14

30-Sep-14

30-Jun-14

31-Mar-14

31-Dec-13

27-Sep-13

28-Jun-13

Dividends Payable, Date to be Paid

27-Apr-15

26-Jan-15

27-Oct-14

25-Jul-14

28-Apr-14

27-Jan-14

25-Oct-13

26-Jul-13

Condensed_Quarterly_Financial_2

Condensed Quarterly Financial Data (Unaudited) (Details) (USD $)	0 Months Ended	3 Months Ended													12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 10, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
INTEREST INCOME (EXPENSE)
Interest income		$11,806	$11,484	$11,575	$11,959	$12,050		$11,223		$4,310		$283		$239	$46,824	$27,866
Interest expense		-1,165	-1,121	-1,070	-1,155	-1,283		-1,248		-525		0		0	-4,511	-3,056
Total net interest income		10,641	10,363	10,505	10,804	10,767		9,975		3,785		283		239	42,313	24,810
EXPENSES
Management fees		552	574	567	592	600		644		703		119		124	2,285	2,066
Professional fees		587	123	137	139	155		200		237		32		125	986	624
Other operating expenses		608	597	613	663	656		513		421		46		45	2,481	1,636
Total expenses		1,747	1,294	1,317	1,394	1,411		1,357		1,361		197		862	5,752	4,326
OTHER INCOME (LOSS)
Net realized gains (losses) on real estate securities and financial derivatives		14,070	-3,425	25,806	14,556	-16,504		-19,900		5,370		888
Change in net unrealized gains (losses) on real estate securities and financial derivatives		-24,140	-2,111	-23,944	-21,205	7,024		18,067		-17,498		155
Total other income (loss)		-10,070	-5,536	1,862	-6,649	-9,480		-1,833		-12,128		1,043		87	-20,393	-22,398
Net income (loss)		($1,176)	$3,533	$11,050	$2,761	($124)		$6,785		($9,704)		$1,129		($536)	$16,168	($1,914)
NET INCOME (LOSS) PER COMMON SHARE:
Basic and Diluted (in dollars per share)		($0.13)	$0.39	$1.21	$0.30	($0.01)	[1]	$0.74	[1]	($1.55)	[1]	$0.69	[1]	($0.33)	$1.77	($0.29)
CASH DIVIDENDS PER COMMON SHARE:
Dividends declared (in dollars per share)	$0.55	$0.55	$0.55	$0.55	$0.55	$0.50		$0.50		$0.14		$0		$0	$2.20	$1.14
[1]	For the year ended December 31, 2013 the sum of EPS for the four quarters of 2013 does not equal EPS as calculated for the entire year (see Note 9) as a result of issuances of common shares, as EPS is calculated using average shares outstanding during the period.

Subsequent_Events_Details

Subsequent Events (Details) (USD $)

0 Months Ended

3 Months Ended

12 Months Ended

Mar. 10, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Subsequent Events [Abstract]

Dividends Payable, Date Declared

11-Mar-15

11-Dec-14

11-Sep-14

17-Jun-14

12-Mar-14

12-Dec-13

17-Sep-13

18-Jun-13

Dividends declared (in dollars per share)

$0.55

$0.55

$0.55

$0.55

$0.55

$0.50

$0.50

$0.14

$0

$0

$2.20

$1.14

Dividends Payable, Date to be Paid

27-Apr-15

26-Jan-15

27-Oct-14

25-Jul-14

28-Apr-14

27-Jan-14

25-Oct-13

26-Jul-13

Dividends Payable, Date of Record

31-Mar-15

31-Dec-14

30-Sep-14

30-Jun-14

31-Mar-14

31-Dec-13

27-Sep-13

28-Jun-13