MTGE Investment (MTGE) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document (USD $)	3 Months Ended
	Mar. 31, 2015	1-May-15	Jun. 30, 2014
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Entity Registrant Name	American Capital Mortgage Investment Corp.
Entity Central Index Key	1516973
Entity Filer Category	Large Accelerated Filer
Current Fiscal Year End Date	-19
Entity Common Stock, Shares Outstanding		51,169,517
Trading Symbol	MTGE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$886,221,142

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets:
Agency securities, at fair value (including pledged securities of $4,113,735 and $4,235,235, respectively)	$4,176,349	$4,384,139
Non-agency securities, at fair value (including pledged securities of $1,042,308 and $940,981, respectively)	1,315,152	1,168,834
US Government Securities, at Carrying Value (including pledged securities of $464,903 and $707,284, respectively)	525,725	758,629
Cash and cash equivalents	184,299	203,431
Restricted cash	111,867	82,144
Interest receivable	15,408	15,249
Derivative assets, at fair value	14,039	28,574
Receivable for agency securities sold	372,245	26,747
Receivable under reverse repurchase agreements	70,636	214,399
Mortgage servicing rights	87,811	93,640
Other assets	52,380	55,466
Total assets	6,925,911	7,031,252
Liabilities:
Secured Debt, Repurchase Agreements	5,459,058	5,423,630
Payable for Agency and Non-Agency Securities Purchased	18,702	49,755
Derivative liabilities, at fair value	113,918	75,981
Dividend payable	26,699	34,374
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements, at Fair Value	91,159	230,136
Accounts payable and other accrued liabilities	35,670	41,407
Total liabilities	5,745,206	5,855,283
Stockholders' equity:
Preferred stock, $0.01 par value; 50,000 shares authorized, 2,200 and 2,200 shares issued and outstanding, respectively	53,039	53,039
Common stock, $0.01 par value; 300,000 shares authorized, 51,165 and 51,165 shares issued and outstanding, respectively	512	512
Additional paid-in capital	1,198,932	1,198,560
Retained earnings	-71,778	-76,142
Total stockholders' equity	1,180,705	1,175,969
Total liabilities and stockholders' equity	$6,925,911	$7,031,252

Consolidated_Balance_Sheets_Co

Consolidated Balance Sheets Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Preferred Stock, Par or Stated Value Per Share	$22	$22
Preferred Stock, Shares Authorized	50,000	50,000
Preferred Stock, Shares Issued	2,200	2,200
Preferred Stock, Shares Outstanding	2,200	2,200
Common Stock, Value, Issued	$512	$512
Common Stock, Shares Authorized	300,000	300,000
Common Stock, Shares, Issued	51,165	51,165
Common Stock, Shares, Outstanding	51,165	51,165
Agency Securities [Member]
Security Owned and Pledged as Collateral, Fair Value	4,113,735	4,235,235
Agency Securities [Member] | Repurchase Agreements [Member]
Security Owned and Pledged as Collateral, Fair Value	4,108,051	4,233,884
Non-Agency Securities [Member] | Repurchase Agreements [Member]
Security Owned and Pledged as Collateral, Fair Value	1,042,308	940,981
US Treasury Securities [Member] | Repurchase Agreements [Member]
Security Owned and Pledged as Collateral, Fair Value	$464,903	$707,284

Consolidated_Statement_Of_Oper

Consolidated Statement Of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest income:
Agency securities	$27,894	$34,272
Non-agency securities	16,928	15,968
Investment Income, Interest	84	56
Interest expense	-7,454	-8,145
Net interest income	37,452	42,151
Servicing:
Other operating income	11,804	9,564
Other noninterest expense	-16,070	-14,222
Net servicing loss	-4,266	-4,658
Other gains (losses):
Realized gain on agency securities, net	934	-13,133
Realized gain on non-agency securities, net	3,246	1,409
Realized loss on periodic settlements of interest rate swaps, net	-4,311	-4,947
Realized gain on other derivatives and securities, net	17,242	-22,028
Unrealized gain on agency securities, net	41,128	67,557
Unrealized gain on non-agency securities, net	-642	7,830
Unrealized loss on other derivatives and securities, net	49,742	19,094
Unrealized gain (loss) mortgage servicing rights	-3,194	-100
Total other gains, net	4,661	17,494
Expenses:
Asset Management Costs	4,508	4,248
General and administrative expenses	1,949	1,830
Total expenses	6,457	6,078
Income before excise tax	31,390	48,909
Excise and TRS tax provision	327	149
Net income	31,063	48,760
Preferred Stock Dividends, Income Statement Impact	-1,117	0
Net Income (Loss) Available to Common Stockholders, Basic	$29,946	$48,760
Earnings Per Share, Basic	$0.59	$0.95
Earnings Per Share, Diluted	$0.58	$0.95
Weighted Average Number of Shares Outstanding, Basic	51,165	51,272
Weighted Average Number of Shares Outstanding, Diluted	51,209	51,272
Common Stock, Dividends, Per Share, Declared	$0.50	$0.65

Consolidated_Statement_of_Stoc

Consolidated Statement of Stockholders' Equity (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]
In Thousands
Beginning Balance, Date Operations Commenced at Dec. 31, 2013	$1,102,720	$0	$514	$1,201,826	($99,620)
Balance, Common Stock, shares at Dec. 31, 2013			51,356
Preferred Stock, Shares Outstanding at Dec. 31, 2013		0
Net income	48,760
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			0
Stock Repurchased During Period, Shares	200		-214
Stock Repurchased During Period, Value	4,200		-3	-4,205
Stock Repurchased and Retired During Period, Value	-4,208
Stock-based compensation	35			35
Common dividends declared	33,242				33,242
Balance at Mar. 31, 2014	1,114,065		511	1,197,656	-84,102
Beginning Balance, Date Operations Commenced at Dec. 31, 2014	1,175,969	53,039
Balance, Common Stock, shares at Dec. 31, 2014	51,165		51,165
Preferred Stock, Shares Outstanding at Dec. 31, 2014	2,200	2,200
Net income	31,063
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures			0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	0
Stock-based compensation	372			372
Dividends, Preferred Stock, Cash	-1,117				-1,117
Common dividends declared	25,582				25,582
Balance at Mar. 31, 2015	$1,180,705	$53,039	$512	$1,198,932	($71,778)
Preferred Stock, Shares Outstanding at Mar. 31, 2015	2,200	2,200
Balance, Common Stock, shares at Mar. 31, 2015	51,165		51,165

Consolidated_Statement_Of_Cash

Consolidated Statement Of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES:
Net income	$31,063	$48,760
Adjustments to reconcile net income to net cash used in operating activities:
Investment Income, Amortization of Premium	8,971	10,794
Accretion of Discount	-9,161	-10,587
Amortization of Mortgage Servicing Rights (MSRs)	2,413	223
Unrealized loss (gain) on securities and derivatives, net	12,450	-56,193
Realized loss (gain) on agency securities, net	-934	13,133
Realized gain on non-agency securities, net	-3,246	-1,409
Realized loss (gain) on derivatives and securities, net	-12,931	28,082
Stock-based compensation	372	35
Increase in interest receivable	-159	4,575
Increase in other assets	3,086	7,055
Increase in accounts payable and other accrued liabilities	-2,459	-3,412
Net cash from (used in) operating activities	29,465	41,056
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Purchases of agency securities	-711,266	-87,901
Purchases of non-agency securities	-246,222	-58,983
Servicing Asset at Fair Value, Additions	-2,736	-20,588
Proceeds from sale of agency securities	430,587	1,331,900
Proceeds from sale of non-agency securities	70,568	44,663
Principal collections on agency securities	127,481	134,133
Proceeds From Principal Collection Of Non Agency Mortgag eBacked Securities	52,368	24,306
Payments for Securities Purchased under Agreements to Resell	143,763	-743,285
Purchase Of US Treasury Securities	-1,702,202	-195,771
Proceeds from sale of U.S. Treasury securities	1,812,984	1,464,370
Proceeds from terminations of interest rate swaptions	0	17,391
Increase (Decrease) in Restricted Cash	-29,723	-37,482
Payments for (Proceeds from) Other Investing Activities	4,748	-37,539
Net cash flows from (used in) investing activities	-49,650	1,835,214
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Payments of Dividends	-34,374	-33,381
Payments for Repurchase of Common Stock	0	-4,208
Proceeds from repurchase agreements	15,509,529	9,691,971
Repayments of Short-term Debt	-15,474,102	-11,546,451
Net cash flow from (used in) financing activities	1,053	-1,892,069
Net increase (decrease) in cash and cash equivalents	-19,132	-15,799
Cash and cash equivalents at beginning of period	203,431	206,398
Cash and cash equivalents at end of period	$184,299	$190,599

Unaudited_Interim_Consolidated

Unaudited Interim Consolidated Financial Statements (Notes)	3 Months Ended
	Mar. 31, 2015
Unaudited Interim Consolidated Financial Statements [Abstract]
Unaudited Interim Consolidated Financial Statements [Text Block]	Unaudited Interim Consolidated Financial Statements
	The unaudited interim consolidated financial statements of American Capital Mortgage Investment Corp. (referred to throughout this report as the "Company", "we", "us" and "our") are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to the requirements for reporting on Form 10-Q and Article 10 of Regulation S-X. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates.
	Our unaudited interim consolidated financial statements include the accounts of our wholly-owned subsidiaries, American Capital Mortgage Investment TRS, LLC, Woodmont Insurance Co., LLC and American Capital Mortgage 2013, LLC and, in turn, its wholly-owned subsidiary Residential Credit Solutions, Inc. ("RCS"). Significant intercompany accounts and transactions have been eliminated. In the opinion of management, all adjustments, consisting solely of normal recurring accruals, necessary for the fair presentation of financial statements for the interim period have been included. The current period’s results of operations are not necessarily indicative of results that ultimately may be achieved for the year.

Organization_Notes

Organization (Notes)	3 Months Ended
	Mar. 31, 2015
Organization [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Organization
	We were incorporated in Maryland on March 15, 2011 and commenced operations on August 9, 2011 following the completion of our initial public offering ("IPO"). We are externally managed by American Capital MTGE Management, LLC (our "Manager"), an affiliate of American Capital, Ltd. ("American Capital"). Our common stock is traded on the NASDAQ Global Select Market under the symbol "MTGE."
	We invest in, finance and manage a leveraged portfolio of mortgage-related investments, which we define to include agency residential mortgage-backed securities ("RMBS"), non-agency mortgage investments and other mortgage-related investments. Agency RMBS include residential mortgage pass-through certificates and collateralized mortgage obligations ("CMOs") structured from residential mortgage pass-through certificates for which the principal and interest payments are guaranteed by a government-sponsored enterprise ("GSE"), such as Federal National Mortgage Association ("Fannie Mae") and Federal Home Loan Mortgage Corporation ("Freddie Mac"), or by a U.S. Government agency, such as Government National Mortgage Association ("Ginnie Mae"). Non-agency mortgage investments include RMBS backed by residential mortgages that are not guaranteed by a GSE or U.S. Government agency. Non-agency mortgage investments may also include prime and non-prime residential mortgage loans. Other mortgage-related investments may include mortgage servicing rights ("MSR"), GSE credit risk transfer securities ("CRT"), commercial mortgage-backed securities ("CMBS"), commercial mortgage loans and mortgage-related derivatives.
	Our objective is to provide attractive risk-adjusted returns to our stockholders over the long-term through a combination of dividends and net book value appreciation. In pursuing this objective, we rely on our Manager’s expertise to construct and manage a diversified mortgage investment portfolio by identifying asset classes that, when properly financed and hedged, are designed to produce attractive returns across a variety of market conditions and economic cycles, considering the risks associated with owning such investments.
	We have elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the "Internal Revenue Code"). As such, we are required to distribute annually at least 90% of our taxable net income. As long as we continue to qualify as a REIT, we will generally not be subject to U.S. Federal or state corporate taxes on our taxable net income to the extent that we distribute all of our annual taxable net income to our stockholders. It is our intention to distribute 100% of our taxable net income, after application of available tax attributes, within the time limits prescribed by the Internal Revenue Code, which may extend into the subsequent taxable year.

Summary_of_Significant_Account

Summary of Significant Accounting Policies (Notes)	3 Months Ended
	Mar. 31, 2015
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Fair Value of Financial Assets
	We have elected the option to account for all of our financial assets, including all mortgage-related investments, at estimated fair value, with changes in fair value reflected in income during the period in which they occur. In management's view, this election more appropriately reflects the results of our operations for a particular reporting period, as financial asset fair value changes are presented in a manner consistent with the presentation and timing of the fair value changes of hedging instruments. See Note 9 - Fair Value Measurements.
	Interest Income
	Interest income is accrued based on the outstanding principal amount of the securities and their contractual terms. Premiums or discounts associated with the purchase of agency RMBS and non-agency securities of high credit quality are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments, using the effective interest method.
	We estimate long-term prepayment speeds using a third-party service and market data. The third-party service estimates prepayment speeds for our securities using models that incorporate the mortgage rates, age, size and loan-to-value ratios of the outstanding underlying loans, as well as current mortgage rates, forward yield curves, volatility and other factors. We review the prepayment speeds estimated by the third-party service and compare the results to market consensus prepayment speeds, if available. We also consider historical prepayment speeds and current market conditions to validate the reasonableness of the prepayment speeds estimated by the third-party service, and based on our Manager’s judgment, we may make adjustments to its estimates. Actual and anticipated prepayment experience is reviewed at least quarterly and effective yields are recalculated when differences arise between the previously estimated future prepayments and the amounts actually received plus currently anticipated future prepayments. If the actual and anticipated future prepayment experience differs from our prior estimate of prepayments, we are required to record an adjustment in the current period to the amortization or accretion of premiums and discounts for the cumulative difference in the effective yield through the reporting date.
	At the time we purchase non-agency securities and loans that are not of high credit quality, we determine an effective yield based on our estimate of the timing and amount of future cash flows and our cost basis. Our initial cash flow estimates for these investments are based on our observations of current information and events and include assumptions related to interest rates, prepayment rates and the impact of default and severity rates on the timing and amount of credit losses. On at least a quarterly basis, we review the estimated cash flows and make appropriate adjustments, based on inputs and analysis received from external sources, internal models, and our judgment about interest rates, prepayment rates, the timing and amount of credit losses, and other factors. Any resulting changes in effective yield are recognized prospectively based on the current amortized cost of the investment as adjusted for credit impairment, if any.
	Mortgage Servicing Rights, at Fair Value
	Our MSR represent the right to service mortgage loans for a servicing fee. MSR are reported at fair value on our consolidated balance sheets, with changes in fair value related to changes in valuation inputs and assumptions reported as unrealized loss on MSR on the consolidated statements of operations. Servicing fees, incentive fees and ancillary income are reported within servicing income on the consolidated statements of operations. The related servicing expenses and realization of cash flows related to underlying loan repayments, net of recoveries of contractual prepayment protection, are recorded in servicing expenses on the consolidated statements of operations. See Note 10 - Mortgage Servicing Rights for further discussion on MSR.
	The accounting model used to evaluate whether a transfer of MSR qualifies as a sale is based on a risks and rewards approach, as MSR are not financial assets. In certain cases where we transfer the economics of MSR while retaining the actual servicing function, we retain the risk associated with servicing and, as a result, the transfer does not qualify for sale accounting. As such, we retain the MSR, together with an offsetting financing liability on our consolidated balance sheets. We have elected the option to account for MSR financing liabilities at estimated fair value, with changes in fair value reflected in income during the period in which they occur. See Note 12 - Accounts Payable and Other Accrued Liabilities for the presentations of our mortgage servicing liability.
	We may be obligated to fund advances of principal and interest payments due to third party loan investors prior to receiving payment on the loans from the individual borrowers. We may also be obligated to fund advances of real estate taxes and insurance, protective advances to preserve the value of the underlying property, and expenses associated with remedial action in respect of defaulted loans. These servicing advances are reported within other assets on the consolidated balance sheets.
	Repurchase Agreements
	We finance the acquisition of agency RMBS and certain non-agency securities for our investment portfolio through repurchase transactions under master repurchase agreements. We account for repurchase transactions as collateralized financing transactions which are carried at their contractual amounts, including accrued interest, as specified in the respective transaction agreements. The contractual amounts approximate fair value due to their short-term nature.
	Reverse Repurchase Agreements and Obligation to Return Securities Borrowed under Reverse Repurchase Agreements
	From time to time we borrow securities to cover short sales of U.S. Treasury securities through reverse repurchase transactions under our master repurchase agreements (see Derivatives below). We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on the consolidated balance sheets based on the value of the underlying borrowed securities as of the reporting date. Our reverse repurchase agreements generally mature daily. The fair value of our reverse repurchase agreements is assumed to equal cost as the interest rates are reset daily.
	Derivatives
	We utilize a risk management strategy, under which we may use a variety of derivative instruments to hedge some of our exposure to market risks, including interest rate risk, prepayment risk, extension risk and credit risk. The objective of our risk management strategy is to reduce fluctuations in net book value over a range of market conditions. The principal instruments that we currently use are interest rate swaps and options to enter into interest rate swaps ("interest rate swaptions"). We also utilize forward contracts for the purchase or sale of agency RMBS, or to-be-announced forward ("TBA") contracts, and short sales of U.S. Treasury securities and U.S. Treasury futures contracts. We may also purchase or write put or call options on TBA securities and we may invest in other types of mortgage derivatives, such as synthetic total return swaps.
	We also enter into TBA contracts as a means of investing in and financing agency RMBS (thereby increasing our "at
	risk" leverage) or as a means of disposing of or reducing our exposure to agency RMBS (thereby reducing our "at risk" leverage). Pursuant to TBA contracts, we agree to purchase or sell, for future delivery, agency RMBS with certain principal and interest terms and certain types of collateral, but the particular agency RMBS to be delivered are not identified until shortly before the TBA settlement date. We may also choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting short or long position (referred to as a "pair off"), net settling the paired off positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date. This transaction is commonly referred to as a "dollar roll." The agency RMBS purchased or sold for a forward settlement date are typically priced at a discount to agency RMBS for settlement in the current month. This difference (or discount) is referred to as the "price drop." The price drop is the economic equivalent of net interest carry income on the underlying agency RMBS over the roll period (interest income less implied financing cost) and is commonly referred to as "dollar roll income (loss)." Consequently, forward purchases of agency RMBS and dollar roll transactions represent a form of off-balance sheet financing.
	We recognize all derivative instruments as either assets or liabilities on the balance sheets, measured at fair value. As we have not designated any derivatives as hedging instruments, all changes in fair value are reported in earnings in our consolidated statements of operations in unrealized gain (loss) on other derivatives and securities, net during the period in which they occur. Derivatives in a gain position are reported as derivative assets at fair value and derivatives in a loss position are reported as derivative liabilities at fair value in our consolidated balance sheets. Cash receipts and payments related to derivative instruments are classified in our consolidated statements of cash flows according to the underlying nature or purpose of the derivative transaction, generally in the investing section.
	Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with each counterparty; however, we report related assets and liabilities on a gross basis in our consolidated balance sheets.
	The use of derivative instruments creates exposure to credit risk relating to potential losses that could be recognized in the event that the counterparties to these instruments fail to perform their obligations under the contracts. We attempt to minimize this risk by limiting our counterparties to major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required.
	Interest rate swap agreements
	We use interest rate swaps to hedge the variable cash flows associated with short-term borrowings made under our repurchase agreement facilities. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one, three or six-month LIBOR ("payer swaps") with terms up to 15 years. The floating rate we receive under our swap agreements has the effect of offsetting the repricing characteristics of our repurchase agreements and cash flows on such liabilities. Our swap agreements are privately negotiated in the over-the-counter ("OTC") market and may be centrally cleared through a registered commodities exchange ("centrally cleared swaps").
	We estimate the fair value of our centrally cleared interest rate swaps using the daily settlement price determined by the respective exchange. Centrally cleared swaps are valued by the exchange using a pricing model that references the underlying rates, including the overnight index swap rate and LIBOR forward rate, to produce the daily settlement price. We estimate the fair value of our "non-centrally cleared" interest rate swaps based on valuations obtained from third-party pricing services and the swap counterparty (collectively, “third-party valuations”). The third-party valuations are model-driven using observable inputs consisting of LIBOR and the forward yield curve. We also consider the creditworthiness of both us and our counterparties and the impact of netting and credit enhancement provisions contained in each derivative agreement, such as collateral postings. All of our "non-centrally cleared" interest rate swaps are subject to bilateral collateral arrangements. Consequently, no credit valuation adjustment was made in determining the fair value of such instruments.
	The payment of periodic settlements of net interest on interest rate swaps is reported in realized loss on periodic settlements of interest rate swaps, net in our consolidated statements of operations. Cash payments received or paid for the early termination of an interest rate swap agreement are recorded as realized gain (loss) on other derivatives and securities, net in our consolidated statements of operations. Changes in fair value of our interest rate swap agreements are reported in unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
	Interest rate swaptions
	We purchase interest rate swaptions to help mitigate the potential impact of larger, more rapid changes in interest rates
	on the performance of our investment portfolio. The interest rate swaptions provide us the option to enter into an interest rate swap agreement for a predetermined notional amount, stated term and pay or receive interest rates in the future. The premium paid for interest rate swaptions is reported as a derivative asset in our consolidated balance sheets. We estimate the fair value of interest rate swaptions based on the fair value of the future interest rate swap that we have the option to enter into as well as the remaining length of time that we have to exercise the option. The difference between the premium and the fair value of the swaption is reported in unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations. If a swaption expires unexercised, the realized loss on the swaption would be equal to the premium paid and reported in realized gain (loss) on other derivatives and securities, net in our consolidated statements of operations. If we exercise a swaption, the realized gain or loss on the swaption would be equal to the difference between the fair value of the underlying interest rate swap and the premium paid and reported in realized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
	Interest rate swaption agreements are privately negotiated in the OTC market and are not subject to central clearing. We estimate the fair value of our interest rate swaption agreements based on model-driven valuations obtained from third-party
	pricing services and the swaption counterparty. These estimates incorporate observable inputs and include the fair value of the future interest rate swaps that we have the option to enter into, as well as the remaining length of time that we have to exercise the options, adjusted for non-performance risk, if any.
	TBA securities
	A TBA security 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 stated maturity on an agreed-upon future date. The specific agency RMBS delivered into the contract upon the settlement date, published each month by the Securities Industry and Financial Markets Association, are not known at the time of the transaction. We may enter into TBA contracts as a means of hedging against short-term changes in interest rates. We may also enter into TBA contracts as a means of acquiring or disposing of agency RMBS and we may from time to time utilize TBA dollar roll transactions to finance agency RMBS purchases.
	We account for all TBA contracts as derivatives since we cannot assert that it is probable at the inception and throughout the term of the contract that it will not settle net and will result in physical delivery of an agency security when it is issued. A TBA dollar roll transaction is a series of derivative transactions. The net settlement of a TBA contract is reported as realized gain (loss) on other derivatives and securities, net and changes in the fair value of our TBA contracts are reported as unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
	We estimate the fair value of TBA securities based on similar methods used to value our agency RMBS.
	Forward commitments to purchase or sell specified securities
	We may enter into a forward commitment to purchase or sell specified securities as a means of acquiring assets or as a hedge against short-term changes in interest rates. Such forward commitments usually require physical settlement. Contracts for the purchase or sale of specified securities are accounted for as derivatives if the delivery of the specified agency RMBS and settlement extends beyond established market conventions. Realized gains and losses associated with forward commitments are recognized in realized gain (loss) on other derivatives and securities, net and unrealized gains and losses are recognized in unrealized gain (loss) on other derivatives and securities, net on our consolidated statements of operations.
	We estimate the fair value of forward commitments to purchase or sell specified RMBS based on methods used to value our RMBS, as well as the remaining length of time of the forward commitment.
	U.S. Treasury securities
	We purchase or sell short U.S. Treasury securities and U.S. Treasury futures contracts to help mitigate the potential impact of changes in interest rates on the performance of our portfolio. Realized gains and losses associated with purchases and short sales of U.S. Treasury securities and U.S. Treasury futures contracts are recognized in realized gain (loss) on other derivatives and securities, net, and unrealized gains and losses are recognized in unrealized gain (loss) on other derivatives and securities, net on our consolidated statements of operations.

Agency_Securities

Agency Securities	3 Months Ended
	Mar. 31, 2015
Agency Securities [Abstract]
Agency Securities	Agency Securities
	The following tables summarize our investments in agency RMBS as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		March 31, 2015
		Fannie Mae				Freddie Mac				Total
	Agency RMBS:
	Par value	$	3,109,841			$	824,977			$	3,934,818
	Unamortized premium	149,456				41,537				190,993
	Amortized cost	3,259,297				866,514				4,125,811
	Gross unrealized gains	43,469				12,441				55,910
	Gross unrealized losses	(3,471		)		(1,901		)		(5,372		)
	Agency RMBS, at fair value	$	3,299,295			$	877,054			$	4,176,349
	Weighted average coupon as of March 31, 2015	3.41		%		3.51		%		3.43		%
	Weighted average yield as of March 31, 2015	2.54		%		2.64		%		2.56		%
	Weighted average yield for the three months ended March 31, 2015	2.46		%		2.52		%		2.47		%
			March 31, 2015
			Amortized Cost				Gross Unrealized Gain				Gross Unrealized Loss				Fair Value
	Agency RMBS:
	Fixed rate		$	4,009,298			$	51,305			$	(5,372	)		$	4,055,231
	Adjustable rate		116,513				4,605				—				121,118
	Total		$	4,125,811			$	55,910			$	(5,372	)		$	4,176,349
		31-Dec-14
		Fannie Mae				Freddie Mac				Total
	Agency RMBS:
	Par value	$	3,333,348			$	857,059			$	4,190,407
	Unamortized premium	141,252				43,070				184,322
	Amortized cost	3,474,600				900,129				4,374,729
	Gross unrealized gains	26,102				7,550				33,652
	Gross unrealized losses	(18,575		)		(5,667		)		(24,242		)
	Agency RMBS, at fair value	$	3,482,127			$	902,012			$	4,384,139
	Weighted average coupon as of December 31, 2014	3.37		%		3.5		%		3.39		%
	Weighted average yield as of December 31, 2014	2.54		%		2.65		%		2.56		%
	Weighted average yield for the year ended December 31, 2014	2.48		%		2.58		%		2.5		%
			31-Dec-14
			Amortized Cost				Gross Unrealized Gain				Gross Unrealized Loss				Fair Value
	Agency RMBS:
	Fixed rate		$	4,252,616			$	30,059			$	(24,242	)		$	4,258,433
	Adjustable rate		122,113				3,593				—				125,706
	Total		$	4,374,729			$	33,652			$	(24,242	)		$	4,384,139
	Actual maturities of agency RMBS are generally shorter than the stated contractual maturities. Actual maturities are affected by the contractual lives of the underlying mortgages, periodic principal payments and principal prepayments.
	The following table summarizes our agency RMBS as of March 31, 2015 and December 31, 2014 according to their estimated weighted average life classification (dollars in thousands):
		March 31, 2015														December 31, 2014
										Weighted Average												Weighted Average
	Weighted Average Life	Fair				Amortized				Yield			Coupon			Fair			Amortized			Yield		Coupon
		Value				Cost										Value			Cost
	Greater than three years and less than or equal to five years	1,525,807				1,501,583				2.19	%		3.08	%		1,528,121			1,520,350			2.13	%	3.05	%
	Greater than five years and less than or equal to 10 years	2,640,117				2,613,977				2.77	%		3.63	%		2,827,653			2,826,297			2.79	%	3.58	%
	Greater than 10 years	10,425				10,251				3.05	%		3.56	%		28,365			28,082			3.12	%	3.52	%
	Total	$	4,176,349			$	4,125,811			2.56	%		3.43	%		$	4,384,139		$	4,374,729		2.56	%	3.39	%
	As of March 31, 2015 and December 31, 2014, none of our agency RMBS had an estimated weighted average life of less than 3.4 years and 3.2 years, respectively. As of March 31, 2015 and December 31, 2014, the estimated weighted average life of our agency security portfolio was 6.5 years and 6.8 years, respectively, which incorporates anticipated future prepayment assumptions. As of March 31, 2015 and December 31, 2014, our weighted average expected constant prepayment rate ("CPR") over the remaining life of our aggregate agency investment portfolio was 9% and 8%, respectively. Our estimates differ materially for different types of securities and thus individual holdings have a wide range of projected CPRs.
	Realized Gains and Losses
	The following table summarizes our net realized gains and losses from the sale of agency RMBS during the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015				2014
	Proceeds from agency RMBS sold		$	430,587			$	1,331,900
	Increase (decrease) in receivable for agency RMBS sold		351,759				(608,646		)
	Less agency RMBS sold, at cost		(781,412		)		(736,387		)
	Net realized gain (loss) on sale of agency RMBS		$	934			$	(13,133	)
	Gross realized gains on sale of agency RMBS		$	3,599			$	1,570
	Gross realized losses on sale of agency RMBS		(2,665		)		(14,703		)
	Net realized gain (loss) on sale of agency RMBS		$	934			$	(13,133	)
	Pledged Assets
	The following tables summarize our agency RMBS pledged as collateral under repurchase agreements and derivative agreements by type as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015
	Agency RMBS Pledged (1)		Fannie Mae				Freddie Mac				Total
Under Repurchase Agreements
Fair value		$	3,236,201			$	871,850			$	4,108,051
Accrued interest on pledged agency RMBS		8,678				2,397				11,075
Under Derivative Agreements
Fair value		5,312				372				5,684
Accrued interest on pledged agency RMBS		14				1				15
Total Fair Value of Agency RMBS Pledged and Accrued Interest		$	3,250,205			$	874,620			$	4,124,825
————————
-1	Agency RMBS pledged do not include pledged amounts of $344.7 million under repurchase agreements related to agency RMBS sold but not yet settled as of March 31, 2015.
		31-Dec-14
Agency RMBS Pledged		Fannie Mae				Freddie Mac				Total
Under Repurchase Agreements
Fair value		$	3,395,257			$	838,627			$	4,233,884
Accrued interest on pledged agency RMBS		9,089				2,335				11,424
Under Derivative Agreements
Fair value		677				674				1,351
Accrued interest on pledged agency RMBS		2				2				4
Total Fair Value of Agency RMBS Pledged and Accrued Interest		$	3,405,025			$	841,638			$	4,246,663
The following table summarizes our agency RMBS pledged as collateral under repurchase agreements by remaining maturity as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		March 31, 2015												December 31, 2014
Remaining Maturity		Fair Value				Amortized				Accrued Interest				Fair Value			Amortized			Accrued Interest
						Cost											Cost
30 days or less		$	1,439,586			$	1,419,399			$	3,870			$	1,711,727		$	1,707,149		$	4,718
31 - 59 days		977,026				962,258				2,619				507,160			503,833			1,310
60 - 90 days		550,304				545,601				1,436				525,089			524,291			1,352
Greater than 90 days		1,141,135				1,131,054				3,150				1,489,908			1,489,667			4,044
Total		$	4,108,051			$	4,058,312			$	11,075			$	4,233,884		$	4,224,940		$	11,424
As of March 31, 2015 and December 31, 2014, none of our repurchase agreement borrowings backed by agency RMBS were due on demand or mature overnight.

NonAgency_Securities

Non-Agency Securities	3 Months Ended
	Mar. 31, 2015
Non-agency Securities [Abstract]
Non-Agency Securities	Non-Agency Securities
	The following tables summarize our non-agency securities as of March 31, 2015 and December 31, 2014 (dollars in thousands):
	March 31, 2015
			Fair			Gross Unrealized							Amortized Cost				Discount				Par/ Current Face				Weighted Average
	Category		Value			Gains			Losses																Coupon (1)			Yield
	Prime		$	213,629		$	8,724		$	(937	)		$	205,842			$	(23,678	)		$	229,520			3.3	%		5.35	%
	CRT		202,893			2,694			(4,166		)		204,365				4,617				199,748				4.3	%		5.56	%
	Alt-A		492,422			41,264			(4,407		)		455,565				(168,167		)		623,732				1.65	%		6.26	%
	Option-ARM		172,390			10,625			(3,145		)		164,910				(40,700		)		205,610				0.44	%		5.47	%
	Subprime		233,818			6,546			(129		)		227,401				(27,527		)		254,928				2.88	%		4.43	%
	Total		$	1,315,152		$	69,853		$	(12,784	)		$	1,258,083			$	(255,455	)		$	1,513,538			2.29	%		5.56	%
	————————
	-1	Coupon rates are floating, except for $15.9 million, $29.1 million and $172.5 million fair value of fixed-rate prime, Alt-A and subprime non-agency securities, respectively, as of March 31, 2015.
	31-Dec-14
			Fair			Gross Unrealized							Amortized Cost				Discount				Par/ Current Face				Weighted Average
	Category		Value			Gains			Losses																Coupon (1)			Yield
	Prime		$	178,215		$	11,346		$	(596	)		$	167,464			$	(25,977	)		$	193,441			3.03	%		6.42	%
	CRT		104,123			88			(5,893		)		109,929				4,150				105,779				4.21	%		5.46	%
	Alt-A		486,254			42,536			(4,090		)		447,808				(169,221		)		617,029				1.67	%		6.54	%
	Option-ARM		173,727			11,317			(2,473		)		164,883				(42,338		)		207,221				0.43	%		5.88	%
	Subprime		226,515			5,818			(342		)		221,039				(29,143		)		250,182				2.7	%		4.57	%
	Total		$	1,168,834		$	71,105		$	(13,394	)		$	1,111,123			$	(262,529	)		$	1,373,652			2.06	%		5.92	%
	————————
	-1	Coupon rates are floating, except for $2.5 million, $29.3 million and $151.2 million fair value of fixed-rate prime, Alt-A and subprime non-agency securities, respectively, as of December 31, 2014.
	The following table summarizes our non-agency securities at fair value, by their estimated weighted average life classifications as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015												31-Dec-14
	Weighted Average Life		Fair Value			Amortized			Weighted			Weighted Average Coupon			Fair Value				Amortized				Weighted			Weighted Average Coupon
						Cost			Average										Cost				Average
									Yield														Yield
	≤ 5 years		$	444,160		$	432,651		4.86	%		2.95	%		$	436,385			$	422,400			5.15	%		2.85	%
	> 5 to ≤ 7 years		527,763			491,161			6.1	%		1.4	%		486,869				446,967				6.68	%		1.29	%
	> 7 years		343,229			334,271			5.68	%		3.05	%		245,580				241,756				5.89	%		2.43	%
	Total		$	1,315,152		$	1,258,083		5.56	%		2.29	%		$	1,168,834			$	1,111,123			5.92	%		2.06	%
	Our Prime non-agency RMBS include investments in securitization trusts collateralized by prime mortgage loans, which are residential mortgage loans that are considered to have been originated with relatively stringent underwriting standards at the time of origination. Our Prime securities with a combined fair value of $200.2 million as of March 31, 2015 are collateralized by loans that were originated between 2002 and 2006, a period of generally weaker underwriting standards and elevated housing prices. As a result, there is still material credit risk embedded in these vintages. As of March 31, 2015, Prime securities also include $13.5 million in fair value of securities with underlying mortgage loans that were originated with more stringent underwriting during 2013. As of March 31, 2015, our Prime securities have both floating-rate and fixed-rate coupons ranging from 0.8% to 6.5%, with weighted average coupons of underlying collateral ranging from 2.4% to 5.8%.
	Our CRT securities are issued by Fannie Mae and Freddie Mac and reference the performance of loans that have been guaranteed by the GSEs, subject to their underwriting standards. As of March 31, 2015, our CRT securities have floating rate coupons ranging from 2.8% to 5.1%, with weighted average coupons of underlying collateral ranging from 3.6% to 4.6%. The loans underlying our CRT securities were originated between 2012 and 2014.
	Our Alt-A non-agency RMBS are collateralized by Alt-A mortgage loans that were originated from 2002 to 2007. Alt-A, or alternative A-paper, mortgage loans are considered to have more credit risk than prime mortgage loans and less credit risk than sub-prime mortgage loans. Alt-A loans are typically characterized by borrowers with less than full documentation, lower credit scores, higher loan-to-value ratios and a higher percentage of investment properties. As of March 31, 2015, our Alt-A securities have both fixed and floating rate coupons ranging from 0.2% to 6.5% with weighted average coupons of underlying collateral ranging from 2.7% to 6.9%.
	Our Option-ARM non-agency RMBS include senior tranches in securitization trusts that are collateralized by residential mortgages that have origination and underwriting characteristics similar to Alt-A mortgage loans, with the added feature of providing underlying mortgage borrowers the option, within certain constraints, to make lower payments than otherwise required by the stated interest rate for a number of years, leading to negative amortization and increased loan balances. This additional feature can increase the credit risk of these securities. As of March 31, 2015, our Option-ARM securities have coupons ranging from 0.3% to 1.0% and have underlying collateral with weighted average coupons between 2.7% and 4.0%. The loans underlying our Option-ARM securities were originated between 2004 and 2007.
	Our Subprime non-agency RMBS issued prior to 2014 include investments in securitization trusts collateralized by residential mortgages originated during or before 2007 that were originally considered to be of lower credit quality. As of March 31, 2015, our Subprime securities issued prior to 2014 have a fair value of $114.3 million with fixed and floating rate coupons ranging from 0.2% to 5.3% and have underlying collateral with weighted-average coupons ranging from 4.4% to 5.9%. Additionally, we have classified certain non-performing loans that were securitized in 2014 and 2015 as Subprime securities. These securitizations are backed by loans originated during or before 2014 and, as of March 31, 2015, have a fair value of $119.5 million. As of March 31, 2015, our Subprime securities issued in 2014 and 2015 have fixed rate coupons ranging from 3.1% to 4.3% and have underlying collateral with weighted-average coupons ranging from 5.1% to 7.7%.
	More than 99% of our non-agency securities are rated below investment grade or have not been rated by credit agencies as of March 31, 2015.
	Realized Gains and Losses
	The following table summarizes our net realized gains and losses from the sale of non-agency securities during the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Proceeds from non-agency securities sold		$	70,568		$	44,663
	Increase in receivable for non-agency RMBS sold		—			4,743
	Less: non-agency securities sold, at cost		(67,322		)	(47,997		)
	Net realized gain on sale of non-agency securities		$	3,246		$	1,409
	Gross realized gain on sale of non-agency securities		$	3,437		$	1,409
	Gross realized loss on sale of non-agency securities		(191		)	—
	Net realized gain on sale of non-agency securities		$	3,246		$	1,409
	Pledged Assets
	Non-agency securities with a fair value of $1.0 billion and $0.9 billion were pledged as collateral under repurchase agreements as of March 31, 2015 and December 31, 2014. As of March 31, 2015 and December 31, 2014, none of our repurchase agreement borrowings backed by non-agency securities were due on demand or mature overnight.
	The following table summarizes our non-agency securities pledged as collateral under repurchase agreements by remaining maturity as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015										December 31, 2014
	Remaining Maturity		Fair Value			Amortized			Accrued Interest				Fair Value				Amortized				Accrued Interest
						Cost											Cost
	30 days or less		$	916,555		$	876,284		$	1,307			$	791,654			$	770,604			$	1,151
	31 - 59 days		83,813			75,353			58				106,097				98,690				77
	60 - 90 days		41,940			38,119			40				43,230				39,280				40
	Total		$	1,042,308		$	989,756		$	1,405			$	940,981			$	908,574			$	1,268

Repurchase_Agreements

Repurchase Agreements	3 Months Ended
	Mar. 31, 2015
Disclosure of Repurchase Agreements [Abstract]
Repurchase Agreements	Repurchase Agreements
	We pledge certain of our securities as collateral under repurchase arrangements with financial institutions, the terms and conditions of which are negotiated on a transaction-by-transaction basis. Interest rates on these borrowings are generally based on LIBOR plus or minus a margin and amounts available to be borrowed are dependent upon the fair value of the securities pledged as collateral, which fluctuates with changes in interest rates, type of security and liquidity conditions within the banking, mortgage finance and real estate industries. In response to declines in fair value of pledged securities, lenders may require us to post additional collateral or pay down borrowings to re-establish agreed upon collateral requirements, referred to as margin calls. As of March 31, 2015 and December 31, 2014, we have met all margin call requirements and had no agency or non-agency repurchase agreements with original overnight maturities. Repurchase agreements are carried at cost, which approximates fair value due to their short-term nature.
	As of March 31, 2015 and December 31, 2014, our borrowings under repurchase agreements had the following collateral characteristics (dollars in thousands):
			March 31, 2015					December 31, 2014
					Weighted Average					Weighted Average
	Collateral Type		Borrowings		Interest Rate		Days	Borrowings		Interest Rate		Days
			Outstanding				to Maturity	Outstanding				to Maturity
	Agency securities (1)		$	4,203,338	0.42	%	213	$	4,002,291	0.42	%	245
	Non-agency securities		791,536		1.66	%	19	715,704		1.67	%	20
	U.S. Treasury securities		464,184		(0.03	)%	5	705,635		(0.13	)%	7
	Total repurchase agreements		$	5,459,058	0.56	%	167	$	5,423,630	0.51	%	190
	————————
	-1	Repurchase agreements borrowings secured by agency securities include $326.2 million of repurchase agreements related to agency RMBS sold but not yet settled as of March 31, 2015.
	The following table summarizes our borrowings under repurchase arrangements and weighted average interest rates classified by remaining maturities as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015					December 31, 2014
					Weighted Average					Weighted Average
			Borrowings		Interest Rate		Days	Borrowings		Interest Rate		Days
			Outstanding				to Maturity	Outstanding				to Maturity
	Agency and non-agency repurchase agreements
	≤ 1 month		$	2,151,856	0.78	%	14	$	2,245,188	0.71	%	13
	> 1 to ≤ 2 months		1,200,075		0.43	%	43	568,014		0.55	%	45
	> 2 to ≤ 3 months		569,598		0.49	%	82	540,201		0.48	%	74
	> 3 to ≤ 6 months		344,549		0.45	%	159	508,216		0.43	%	142
	> 6 to ≤ 9 months		213,796		0.52	%	237	123,947		0.51	%	246
	> 9 to ≤ 12 months		—		—	%	0	217,429		0.51	%	327
	> 12 months		515,000		0.65	%	1315	515,000		0.63	%	1405
	Total		4,994,874		0.62	%	183	4,717,995		0.61	%	210
	U.S. Treasury repurchase agreements
	Short-term		464,184		(0.03	)%	5	705,635		(0.13	)%	7
	Total repurchase agreements		$	5,459,058	0.56	%	167	$	5,423,630	0.51	%	190
	We had repurchase agreements with 32 and 31 financial institutions as of March 31, 2015 and December 31, 2014, respectively. In addition, less than 5% of stockholders' equity was at risk due to collateral pledged in excess of borrowings under repurchase agreements with any one counterparty, with the top five counterparties representing less than 21% of our equity at risk as of March 31, 2015.
	We had agency RMBS with fair values of $4.1 billion and $4.2 billion as of March 31, 2015 and December 31, 2014, respectively, and non-agency securities with fair values of $1.0 billion and $0.9 billion pledged as collateral against repurchase agreements as of March 31, 2015 and December 31, 2014, respectively.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2015
Derivative Instruments [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivatives and Other Securities
	In connection with our risk management strategy, we hedge a portion of our exposure to market risks, including interest rate risk and prepayment risk, by entering into derivative and other hedging instrument contracts. We may enter into agreements for interest rate swaps, interest rate swaptions, interest rate cap or floor contracts and futures or forward contracts. We may also purchase or short TBA and U.S. Treasury securities, purchase or write put or call options on TBA securities or we may invest in other types of derivative securities, including synthetic total return swaps and credit default swaps. Our risk management strategy attempts to manage the overall risk of the portfolio and reduce fluctuations in book value. We do not use derivative or other hedging instruments for speculative purposes. Derivatives have not been designated as hedging instruments. We do not offset our derivatives and related cash collateral with the same counterparties under any master netting arrangements. For additional information regarding our derivative instruments and our overall risk management strategy, please refer to the discussion of derivatives in Note 3.
	The table below presents the balance sheet location and fair value information for our derivatives outstanding as of March 31, 2015 and December 31, 2014 (in thousands):
			31-Mar-15				31-Dec-14
	Interest rate swaps		$	466			$	9,414
	Interest rate swaptions		3,667				5,464
	TBA securities		9,272				13,495
	Interest only swaps		634				201
	Derivative assets, at fair value		$	14,039			$	28,574
	Interest rate swaps		$	106,059			$	73,052
	TBA securities		4,823				1,863
	Mortgage options		37				—
	U.S. Treasury futures		2,999				1,066
	Derivative liabilities, at fair value		$	113,918			$	75,981
	The following table summarizes the effect of our outstanding derivatives and other securities on our consolidated statements of operations during the three months ended March 31, 2015 and 2014 (in thousands):
			For the Three Months Ended March 31,
			2015										2014
			Realized Loss on Periodic Settlements of Interest Rate Swaps, net			Realized Gain (Loss) on Other Derivatives and Securities, net			Unrealized Gain (Loss) on Other Derivatives and Securities, net				Realized Loss on Periodic Settlements of Interest Rate Swaps, net			Realized Gain (Loss) on Other Derivatives and Securities, net			Unrealized Gain (Loss) on Other Derivatives and Securities, net
	Interest rate swaps		$	(4,311	)	$	(7,825	)	$	(43,106	)		$	(4,947	)	$	68		$	(28,164	)
	Interest rate swaptions		—			(520		)	(1,277		)		—			(14,668		)	(6,483		)
	TBA securities		—			16,436			(7,183		)		—			(8,829		)	(829		)
	U.S. Treasuries		—			15,901			2,655				—			1,047			10,958
	U.S. Treasury futures		—			(2,215		)	(1,933		)		—			(774		)	(2,238		)
	Short sales of U.S. Treasuries		—			(5,181		)	321				—			(1,547		)	3,820
	REIT equity investments		—			—			—				—			2,675			3,842
	Mortgage options		—			—			353				—			—			—
	Interest only swap		—			646			428				—			—			—
	Total		$	(4,311	)	$	17,242		$	(49,742	)		$	(4,947	)	$	(22,028	)	$	(19,094	)
	The following tables summarize changes in notional amounts for our outstanding derivatives and other securities for the three months ended March 31, 2015 and 2014 (in thousands):
		31-Dec-14				Additions/ Long Positions			Expirations/			31-Mar-15
		Notional							Terminations/ Short Positions			Notional
		Amount										Amount
	Interest rate swaps	$	4,015,000			—			(600,000	)		$	3,415,000
	Interest rate swaptions	$	550,000			—			(100,000	)		$	450,000
	TBA securities	$	296,172			10,373,879			(10,407,731	)		$	262,320
	U.S. Treasuries	$	756,500			1,323,000			(1,558,000	)		$	521,500
	U.S. Treasury futures	$	(150,000	)		150,000			(150,000	)		$	(150,000	)
	Short sales of U.S. Treasuries	$	(228,500	)		364,000			(226,500	)		$	(91,000	)
	Mortgage options	$	—			—			(50,000	)		$	(50,000	)
	Interest only swaps	$	48,739			—			(2,238	)		$	46,501
		31-Dec-13				Additions/ Long Positions			Expirations/			31-Mar-14
		Notional							Terminations/ Short Positions			Notional
		Amount										Amount
	Interest rate swaps	$	3,240,000			850,000			(50,000	)		$	4,040,000
	Interest rate swaptions	$	2,100,000			—			(1,675,000	)		$	425,000
	TBA securities	$	(773,816	)		4,360,686			(2,912,089	)		$	674,781
	U.S. Treasuries	$	656,000			150,000			(681,000	)		$	125,000
	U.S. Treasury futures	$	(150,000	)		150,000			(150,000	)		$	(150,000	)
	Short sales of U.S. Treasuries	$	(23,000	)		48,000			(790,000	)		$	(765,000	)
	Interest Rate Swap Agreements
	As of March 31, 2015 and December 31, 2014, our derivative portfolio included interest rate swaps, which have the effect of modifying the repricing characteristics of our repurchase agreements and cash flows on such liabilities. Our interest rate swaps are used to manage the interest rate risk created by our use of short-term repurchase agreements. Under our interest rate swaps, we typically pay a fixed rate and receive a floating rate based on LIBOR with terms usually ranging up to 15 years. As of March 31, 2015 and December 31, 2014, we had interest rate swap agreements summarized in the tables below (dollars in thousands).
					31-Mar-15								31-Dec-14
	Interest Rate Swaps		Balance Sheet Location		Notional Amount				Fair Value				Notional Amount				Fair Value
	Interest rate swap assets		Derivative assets, at fair value		$	425,000			$	466			$	925,000			$	9,414
	Interest rate swap liabilities		Derivative liabilities, at fair value		2,990,000				(106,059		)		3,090,000				(73,052		)
					$	3,415,000			$	(105,593	)		$	4,015,000			$	(63,638	)
	March 31, 2015
			Notional				Fair Value				Weighted Average
			Amount
	Current Maturity Date for Interest Rate Swaps (1)										Fixed			Receive			Maturity
											Pay Rate (2)			Rate (3)			(Years)
	≤ 3 years		$	865,000			$	(3,973	)		1.01	%		0.26	%		1.7
	> 3 to ≤ 5 years		900,000				(16,208		)		1.94	%		0.26	%		4
	> 5 to ≤ 7 years		1,300,000				(63,589		)		2.86	%		0.26	%		6
> 7 years		350,000				(21,823		)		2.78	%		0.26	%		8.3
Total		$	3,415,000			$	(105,593	)		2.14	%		0.26	%		4.6
December 31, 2014
		Notional				Fair Value				Weighted Average
Current Maturity Date for Interest Rate Swaps (4)		Amount								Fixed			Receive			Maturity
										Pay Rate (2)			Rate (3)			(Years)
≤ 3 years		$	1,065,000			$	(1,635	)		0.97	%		0.23	%		1.6
> 3 to ≤ 5 years		850,000				(4,441		)		1.91	%		0.23	%		4.2
> 5 to ≤ 7 years		1,625,000				(38,780		)		2.66	%		0.23	%		6
> 7 years		475,000				(18,782		)		2.87	%		0.25	%		8.2
Total		$	4,015,000			$	(63,638	)		2.08	%		0.23	%		4.7
————————
(1)	Includes swaps with an aggregate notional of $1.8 billion with deferred start dates averaging 0.9 years from March 31, 2015.
(2)	Excluding forward starting swaps, the weighted average pay rate was 1.37% and 1.24% as of March 31, 2015 and December 31, 2014, respectively.
(3)	Weighted average receive rate excludes impact of forward starting interest rate swaps.
(4)	Includes swaps with an aggregate notional of $2.1 billion with deferred start dates averaging 1.1 years from December 31, 2014.
As of March 31, 2015, interest rate swaps with a notional amount of $2.1 billion and liability fair value of $(98.0) million were centrally cleared on a registered exchange.
Interest Rate Swaption Agreements
Our interest rate swaption agreements provide us the option to enter into interest rate swap agreements in the future where we would pay a fixed rate and receive LIBOR. The following tables present certain information about our interest rate swaption agreements as of March 31, 2015 and December 31, 2014 (dollars in thousands):
March 31, 2015
		Option										Underlying Swap
Current Option Expiration Date		Cost				Fair Value				Weighted Average Years to Expiration		Notional Amount				Pay Rate			Weighted Average Term (Years)
> 3 to ≤ 12 months		$	6,631			$	2,219			0.6		$	250,000			3.23	%		8.7
>12 to ≤ 24 months		1,308				82				1		100,000				4.13	%		7
> 24 months		2,735				1,366				2.6		100,000				3.21	%		5
Total / weighted average		$	10,674			$	3,667			1.2		$	450,000			3.43	%		7.5
December 31, 2014
		Option										Underlying Swap
Current Option Expiration Date		Cost				Fair Value				Weighted Average Years to Expiration		Notional Amount				Pay Rate			Weighted Average Term (Years)
≤ 3 months		$	4,013			$	1,972			0.1		$	150,000			2.78	%		4.3
> 3 to ≤ 12 months		3,139				1,432				0.9		200,000				3.29	%		8.8
>12 to ≤ 24 months		1,308				207				1.3		100,000				4.13	%		7
> 24 months		2,735				1,853				2.9		100,000				3.21	%		5
Total / weighted average		$	11,195			$	5,464			1.1		$	550,000			3.29	%		6.5
TBA Securities
As of March 31, 2015 and December 31, 2014, we had contracts to purchase ("long position") and sell ("short position") TBA securities on a forward basis, presented in the following table (in thousands):
		31-Mar-15								31-Dec-14
Purchase and Sale Contracts for TBA Securities		Notional				Fair				Notional				Fair
		Amount (1)				Value (2)				Amount (1)				Value (2)
TBA assets
Purchase of TBA securities		$	745,898			$	9,272			$	829,030			$	8,226
Sale of TBA securities		—				—				(74,758		)		5,269
Total TBA assets		745,898				9,272				754,272				13,495
TBA liabilities
Purchase of TBA securities		297,930				(1,682		)		199,000				(595		)
Sale of TBA securities		(781,508		)		(3,141		)		(657,100		)		(1,268		)
Total TBA liabilities		(483,578		)		(4,823		)		(458,100		)		(1,863		)
Total net TBA		$	262,320			$	4,449			$	296,172			$	11,632
————————
(1)	Notional amount represents the par value or principal balance of the underlying agency security.
(2)	Fair value represents the current market value of the agency RMBS underlying the TBA contract as of period end, less the forward price to be paid for the underlying agency RMBS.
U.S. Treasury Securities and Futures
We purchase or sell short U.S. Treasury securities and U.S. Treasury futures contracts to help mitigate the potential impact of changes in interest rates on the performance of our portfolio. We had U.S. Treasury securities with a fair value of $525.7 million and $758.6 million and a face amount of $521.5 million and $756.5 million as of March 31, 2015 and December 31, 2014, respectively, which is presented as U.S. Treasury securities, at fair value on the consolidated balance sheets. In addition, we had a short position in U.S. Treasury futures with a fair value of $(3.0) million and $(1.1) million, respectively, and a notional amount of $(150.0) million as of both March 31, 2015 and December 31, 2014, which is presented in derivative assets, at fair value on the consolidated balance sheets.
We had obligations to return U.S. Treasury securities borrowed under reverse repurchase agreements accounted for as securities borrowing transactions with a fair value of $91.2 million and $230.1 million as of March 31, 2015 and December 31, 2014, respectively. The borrowed securities were collateralized by cash payments of $70.6 million and $214.4 million as of March 31, 2015 and December 31, 2014, respectively, which are presented as receivables under reverse repurchase agreements on the consolidated balance sheets. All changes in fair value of long and short U.S. Treasury securities and futures are recorded in unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
Credit Risk-Related Contingent Features
The use of derivatives creates exposure to credit risk relating to potential losses that could be recognized in the event that the counterparties to these instruments fail to perform their obligations under the contracts. We minimize this risk by limiting our counterparties for instruments which are not centrally cleared on a registered exchange to major financial institutions with acceptable credit ratings and monitoring positions with individual counterparties. In addition, both we and our counterparties may be required to pledge assets as collateral for our derivatives, whose amounts vary over time based on the market value, notional amount and remaining term of the derivative contract. In the event of a default by a counterparty, we may not receive payments provided for under the terms of our derivative agreements, and may have difficulty obtaining our assets pledged as collateral for our derivatives. The cash and cash equivalents pledged as collateral for our derivative instruments is included in restricted cash and cash equivalents on our consolidated balance sheets.
Each of our ISDA Master Agreements contains provisions pursuant to which we are required to fully collateralize our obligations under our interest rate swap agreements if at any point the fair value of the swap represents a liability greater than the minimum transfer amount contained within our ISDA Master Agreements. We are also required to post initial collateral upon execution of certain of our swap transactions. If we breach any of these provisions, we will be required to settle our obligations under the agreements at their termination values, which approximates fair value.
Further, each of our ISDA Master Agreements also contains a cross default provision under which a default under certain of our other indebtedness in excess of a certain threshold causes an event of default under the agreement. Threshold amounts vary by lender. Following an event of default, we could be required to settle our obligations under the agreements at their termination values. Additionally, under certain of our ISDA Master Agreements, we could be required to settle our obligations under the agreements at their termination values if we fail to maintain either our REIT status or certain minimum stockholders’ equity thresholds, or comply with limits on our leverage above certain specified levels. As of March 31, 2015, the fair value of the additional collateral that could be required to be posted as a result of the credit-risk related contingent features being triggered was not material to our consolidated financial statements.
Concerning our non-centrally cleared interest rate swap and swaption agreements, we did not have counterparty credit risk with any single counterparty in excess of 1% of our stockholders’ equity, as of March 31, 2015.
In the case of centrally cleared interest rate swap contracts, we could be exposed to credit risk if the central clearing agency or a clearing member defaults on its respective obligation to perform under the contract; however, the risk is considered minimal due to initial and daily exchange of mark to market margin requirements and the clearinghouse guarantee fund and other resources that are available in the event of a clearing member default.

Offsetting_Assets_and_Liabilit

Offsetting Assets and Liabilities (Notes)	3 Months Ended
	Mar. 31, 2015
Offsetting Assets and Liabilities [Abstract]
Offsetting Assets and Liabilities [Text Block]	Offsetting Assets and Liabilities
	Certain of our repurchase agreements and derivative transactions are governed by underlying agreements that generally provide for a right of offset under master netting arrangements (or similar agreements), including in the event of default or in the event of bankruptcy of either party to the transactions.  We present our assets and liabilities subject to such arrangements on a gross basis in our consolidated balance sheets.
	The following tables present information about our assets and liabilities that are subject to such agreements and can potentially be offset on our consolidated balance sheets as of March 31, 2015 and December 31, 2014 (in thousands):
	Offsetting of Financial Assets and Derivative Assets:
			Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts Presented		Gross Amounts Not Offset in the Consolidated Balance Sheets
							in the Consolidated Balance Sheets		Financial Instruments			Collateral Received (1)			Net Amount
	March 31, 2015
	Interest rate swaps and swaptions (2)(3)		$	4,133	$	—	$	4,133	$	(1,296	)	$	(1,351	)	$	1,486
	Receivable under reverse repurchase agreements		70,636		—		70,636		(70,636		)	—			—
	Total		$	74,769	$	—	$	74,769	$	(71,932	)	$	(1,351	)	$	1,486
	December 31, 2014
	Interest rate swaps and swaptions (2)		$	14,878	$	—	$	14,878	$	(5,192	)	$	(3,059	)	$	6,627
	Receivable under reverse repurchase agreements		214,399		—		214,399		(214,399		)	—			—
	Total		$	229,277	$	—	$	229,277	$	(219,591	)	$	(3,059	)	$	6,627
	Offsetting of Financial Liabilities and Derivative Liabilities:
			Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts Presented		Gross Amounts Not Offset in the Consolidated Balance Sheets
							in the Consolidated Balance Sheets		Financial Instruments			Collateral Pledged (1)			Net Amount
	March 31, 2015
	Interest rate swaps (2)		$	106,059	$	—	$	106,059	$	(1,296	)	$	(104,763	)	$	—
	Repurchase agreements		5,459,058		—		5,459,058		(70,636		)	(5,388,422		)	—
	Total		$	5,565,117	$	—	$	5,565,117	$	(71,932	)	$	(5,493,185	)	$	—
	December 31, 2014
	Interest rate swaps (2)		$	73,052	$	—	$	73,052	$	(5,192	)	$	(67,860	)	$	—
	Repurchase agreements		5,423,630		—		5,423,630		(214,399		)	(5,209,231		)	—
	Total		$	5,496,682	$	—	$	5,496,682	$	(219,591	)	$	(5,277,091	)	$	—
	————————
	-1	Includes cash and securities received / pledged as collateral, at fair value. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero on a counterparty by counterparty basis, as applicable. Refer to Notes 4 and 5 for additional information regarding assets pledged as collateral.
	-2	Reported under derivative assets / liabilities, at fair value in the accompanying consolidated balance sheets. Refer to Note 7 for a reconciliation of derivative assets / liabilities, at fair value to their sub-components.
	(3)	Interest rate swaps and swaptions are subject to master netting arrangements which could reduce our maximum amount of loss due to credit risk by $1.3 million as of March 31, 2015.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Measurements
	We have elected the option to account for all of our financial assets, including RMBS, at fair value, with changes in fair value reflected in income during the period in which they occur. We have determined that this presentation most appropriately represents our financial results and position. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, based on the assumptions market participants would use when pricing an asset or liability.
	We determine the fair value of our agency and non-agency securities, including securities held as collateral, based upon fair value estimates obtained from multiple third-party pricing services and dealers. In determining fair value, third-party pricing sources use various valuation approaches, including market and income approaches. Factors used by third-party sources in estimating the fair value of an instrument may include observable inputs such as recent trading activity, credit data, volatility statistics, and other market data that are current as of the measurement date. The availability of observable inputs can vary by instrument and is affected by a wide variety of factors, including the type of instrument, whether the instrument is new and not yet established in the marketplace and other characteristics particular to the instrument. Third-party pricing sources may also use certain unobservable inputs, such as assumptions of future levels of prepayment, default and loss severity, especially when estimating fair values for securities with lower levels of recent trading activity. When possible, we make inquiries of third-party pricing sources to understand their use of significant inputs and assumptions.
	We review the various third-party fair value estimates and perform procedures to validate their reasonableness, including an analysis of the range of third-party estimates for each position, comparison to recent trade activity for similar securities, and our Manager's review for consistency with market conditions observed as of the measurement date. While we do not adjust prices we obtain from third-party pricing sources, we will exclude third-party prices for securities from our determination of fair value if we determine (based on our validation procedures and our Manager's market knowledge and expertise) that the price is significantly different than observable market data would indicate and we cannot obtain a satisfactory understanding from the third party source as to the significant inputs used to determine the price.
	We determine the fair value of our MSR based upon third party estimates, corroborated by internally developed discounted cash flow models that utilize observable market-based inputs and include substantial unobservable market data inputs (including prepayment speeds, delinquency levels and discount rates).
	We utilize a three-level valuation hierarchy for disclosure of fair value measurement. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. A financial instrument’s categorization within the hierarchy is based upon the lowest level of input that is significant to the fair value measurement. We use the results of the validation procedures described above as part of our determination of the appropriate fair value measurement hierarchy classification. The three levels of hierarchy are defined as follows:
	•	Level 1 Inputs - Quoted prices (unadjusted) for identical unrestricted assets and liabilities in active markets that are accessible at the measurement date.
	•	Level 2 Inputs - Quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations whose inputs are observable or whose significant value drivers are observable.
	•	Level 3 Inputs - Significant unobservable market inputs that are supported by little or no market activity. The unobservable inputs represent the assumptions that market participants would use to price the assets and liabilities.
	The following tables present our financial instruments carried at fair value as of March 31, 2015 and December 31, 2014, on the consolidated balance sheets by the valuation hierarchy, as described above (in thousands):
			March 31, 2015
			Level 1			Level 2			Level 3			Total
	Assets
	Agency RMBS		$	—		$	4,176,349		$	—		$	4,176,349
	Non-agency securities		—			1,315,152			—			1,315,152
	U.S. Treasury securities		525,725			—			—			525,725
	Derivative assets		—			14,039			—			14,039
	MSR assets		—			—			87,811			87,811
	Total		$	525,725		$	5,505,540		$	87,811		$	6,119,076
	Liabilities
	Derivative liabilities		$	—		$	113,918		$	—		$	113,918
	Obligation to return securities borrowed under reverse repurchase agreements		91,159			—			—			91,159
	MSR financing liabilities		—			—			13,380			13,380
	Total		$	91,159		$	113,918		$	13,380		$	218,457
			December 31, 2014
			Level 1			Level 2			Level 3			Total
	Assets
	Agency RMBS		$	—		$	4,384,139		$	—		$	4,384,139
	Non-agency securities		—			1,168,834			—			1,168,834
	U.S. Treasury securities		758,629			—			—			758,629
	Derivative assets		—			28,574			—			28,574
	MSR assets		—			—			93,640			93,640
	Total		$	758,629		$	5,581,547		$	93,640		$	6,433,816
	Liabilities
	Derivative liabilities		$	—		$	75,981		$	—		$	75,981
	Obligation to return securities borrowed under reverse repurchase agreements		230,136			—			—			230,136
	MSR financing liabilities		—			—			14,003			14,003
	Total		$	230,136		$	75,981		$	14,003		$	320,120
	Our agency and non-agency securities are valued using the various market data described above, which include inputs determined to be observable or whose significant value drivers are observable. Accordingly, our agency and non-agency securities are classified as Level 2 in the fair value hierarchy as of March 31, 2015.
	For information regarding valuation of our derivative instruments, please refer to the discussion of derivative and other hedging instruments in Note 3. Our interest rate swaps and other derivatives are classified as Level 2 in the fair value hierarchy.
	The fair value of our obligation to return securities borrowed under reverse repurchase agreements is based upon the value of the underlying borrowed U.S. Treasury securities as of the reporting date. Both U.S. Treasury securities and our obligation to return borrowed U.S. Treasury securities are classified as Level 1 in the fair value hierarchy.
	Excluded from the table above are financial instruments, including cash and cash equivalents, restricted cash, receivables, payables and borrowings under repurchase agreements, which are presented in our consolidated financial statements at cost, which is determined to approximate fair value, primarily due to the short duration of these instruments.  The cost basis of repurchase agreement borrowings with initial terms of greater than one year is determined to approximate fair value, primarily as such agreements have floating rates based on an index plus or minus a fixed spread and the fixed spread is generally consistent with those demanded in the market.   We estimate the fair value of these instruments using Level 2 inputs.
	The following table presents a summary of the changes in fair value for Level 3 assets carried at fair value for the three months ended March 31, 2015 and 2014 (in thousands):
			For the Three Months Ended March 31, 2015
			MSR Under Secured Financing (1)			Purchased MSR (2)			Total MSR
	Balance as of December 31, 2014		$	14,003		$	79,637		$	93,640
	Losses included in net income:
	Realized losses		(462		)	(2,413		)	(2,875		)
	Unrealized losses		(161		)	(3,194		)	(3,355		)
	Total net losses included in net income		(623		)	(5,607		)	(6,230		)
	Purchases, net of purchase price adjustments		—			401			401
	Balance as of March 31, 2015		$	13,380		$	74,431		$	87,811
			For the Three Months ended March 31, 2014
			MSR Under Secured Financing (1)			Purchased MSR (2)			Total MSR
	Balance as of December 31, 2013		$	15,608		$	—		$	15,608
	Losses included in net income:
	Realized losses		(202		)	(223		)	(425		)
	Unrealized losses		(31		)	(100		)	(131		)
	Total net losses included in net income		(233		)	(323		)	(556		)
	Purchases, net of purchase price adjustments		—			23,456			23,456
	Balance as of March 31, 2014		$	15,375		$	23,133		$	38,508
	————————
	-1	Losses included in net income related to MSR under secured financing are offset in their entirety by gains associated with related MSR financing liabilities.
	(2)	Realized losses of $(2.4) million and $(0.2) million on purchased MSR are included in servicing expense and unrealized losses of $(3.2) million and $(0.1) million are included in unrealized loss on mortgage servicing rights, respectively, on the consolidated statements of operations for the three months ended March 31, 2015 and 2014.
We use third-party pricing providers in the fair value measurement of our Level 3 MSR. The significant unobservable inputs used in estimating the fair value measurement of our Level 3 MSR assets and financing liabilities include assumptions for underlying loan constant prepayment rates and delinquency rates, as well as discount rates. We review the various third-party fair value estimates used to determine the fair value of our MSR and perform procedures to validate their reasonableness. In reviewing the estimated fair values of our Level 3 MSR, we use internal models and estimates of prepayment and
delinquency rates on the loans underlying our MSR.
The following table presents the range of our estimates of loan constant voluntary prepayment rates and constant default rates, together with the discount rates used by third-party pricing providers in estimating the fair value of our Level 3 MSR as of March 31, 2015 (dollars in thousands):
		March 31, 2015
Unobservable Level 3 Input		Fair Value			Minimum		Weighted	Maximum
							Average
MSR treated as financing arrangements:		$	13,380
Constant prepayment rate					5.60%		15.00%	33.20%
Constant default rate					2.50%		7.60%	26.70%
Discount rate					16.00%		16.00%	16.00%
Purchased MSR:		74,431
Constant prepayment rate					9.00%		9.10%	9.30%
Constant default rate					0.20%		0.30%	0.40%
Discount rate					8.30%		8.70%	9.30%
Total		$	87,811
Our MSR treated as financing arrangements relate to private label mortgages with an average origination year of 2005, whereas our purchased MSR relate to more recently originated mortgages that conform to GSE underwriting standards. Private label originations from the pre-2009 era have experienced heightened default rates relative to recently originated conforming mortgages. As such, we anticipate that the default rate and discount rate for our MSR treated as financing arrangements will exceed the default rate and discount rate for our purchased MSR.
A significant increase in any one of these individual inputs in isolation would likely result in a decrease in fair value measurement. Additionally, a change in the assumption used for discount rates may be accompanied by a directionally similar change in the assumption used for the probability of delinquency and a directionally opposite change in the assumption used for prepayment rates. Overall MSR market conditions could have a more significant impact on our Level 3 fair values than changes in any one unobservable input.

Mortgage_Servicing_Rights_Note

Mortgage Servicing Rights (Notes)	3 Months Ended
	Mar. 31, 2015
Servicing Assets at Fair Value [Line Items]
Transfers and Servicing of Financial Assets [Text Block]	Mortgage Servicing Rights
	Our $87.8 million balance of MSR as of March 31, 2015 includes $13.4 million related to RCS' acquisition of certain MSR covering private label residential mortgage pools, for which RCS entered into sale and assignment agreements with a third party to transfer its interest in the excess MSR while retaining the actual servicing function. These transfers do not qualify for sale accounting and are treated as financing arrangements, under which we recognize both MSR assets and corresponding MSR financing liabilities. Changes in the fair value of assets and liabilities resulting from MSR financing transactions have no net impact on the consolidated statements of operations.
	RCS purchased the remaining $74.4 million of MSR under transactions qualifying for sale accounting, representing approximately 33 thousand underlying loans, with a combined unpaid principal balance of approximately $6.9 billion, as of March 31, 2015. We have elected to account for all MSR assets and MSR financing liabilities at estimated fair value with changes in fair value reported in net income. The following table summarizes activity related to MSR accounted for as purchases during the three months ended March 31, 2015 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Beginning balance		$	79,637		$	—
	Additions from purchases of MSR		401			23,456
	Changes in fair value due to:
	Changes in valuation inputs or assumptions used in valuation model		(3,194		)	(100		)
	Other changes in fair value (1)		(2,413		)	(223		)
	Ending balance		$	74,431		$	23,133
	————————
	1	Other changes in fair value primarily represents changes due to the realization of cash flows.
	The following table presents the components of net servicing loss for the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Servicing fee income		$	7,948		$	5,823
	Incentive, ancillary and other income		3,856			3,741
	Servicing income		11,804			9,564
	Employee compensation and benefit costs		7,397			8,777
	Facility costs		2,828			2,933
	Realization of cash flows from MSR		2,413			223
	Other servicing costs		3,432			2,289
	Servicing expense		16,070			14,222
	Net servicing loss		$	(4,266	)	$	(4,658	)
	Risk Mitigation Activities
	The Company’s acquisitions of MSR expose us to certain risks, including interest rate risk and representation and warranty risk. A significant decline in interest rates could lead to higher-than-expected prepayments that could reduce the value of the MSR. Our primary method of managing the prepayment risk associated with our MSR portfolio is asset selection, both in respect of products and the originators of the underlying loans. Representation and warranty risk refers to the representations and warranties we make (or are deemed to have made) to the applicable investor (including, without limitation, the GSEs) regarding, among other things, the origination and servicing of mortgage loans with respect to which we have acquired MSR. We mitigate representation and warranty risk through our due diligence in connection with MSR acquisitions, including counterparty reviews and loan file reviews, as well as negotiated contractual protections from our MSR transaction counterparties with respect to origination and prior servicing.

Other_Assets_Notes

Other Assets (Notes)	3 Months Ended
	Mar. 31, 2015
Other Assets [Abstract]
Other Assets Disclosure [Text Block]	Other Assets
	The following table summarizes our other assets as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		March 31, 2015			December 31, 2014
	Property and equipment, at cost	$	4,837		$	4,809
	Accumulated depreciation	(2,246		)	(1,877		)
	Net property and equipment	2,591			2,932
	Servicing advances	21,312			24,393
	Prepaid expenses	8,089			7,089
	Intangible assets	15,000			15,000
	Other	5,388			6,052
	Total other assets	$	52,380		$	55,466
	Servicing Advances
	We are required to fund cash advances in connection with our servicing operations. These servicing advances are reported within other assets on the consolidated balance sheets and represent advances for principal and interest, property taxes and insurance, as well as certain out-of-pocket expenses incurred by the Company in the performance of its servicing obligations.

Other_Liabilities_Notes

Other Liabilities (Notes)	3 Months Ended
	Mar. 31, 2015
Other Liabilities [Abstract]
Other Liabilities Disclosure [Text Block]	Accounts Payable and Other Accrued Liabilities
	The following table summarizes our accounts payable and other accrued liabilities as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015		December 31, 2014
	Cash collateral held on derivatives		$	1,351	$	2,298
	Due to manager		2,011		1,763
	Swaption premium payable		—		520
	Payable for MSR purchased		345		2,680
	Accrued interest		3,758		4,642
	Mortgage servicing financing, at fair value (1)		13,380		14,003
	Other accounts payable and accrued expenses		14,825		15,501
	Total accounts payable and other accrued liabilities		$	35,670	$	41,407
	——————
	-1	Mortgage servicing financing represents our obligations associated with excess MSR transferred to a third party which are accounted for as financing arrangements. We have elected the option to account for MSR financing at estimated fair value with changes in fair value reported in net income.

Stockholders_Equity_Notes

Stockholder's Equity (Notes)	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Attributable to Parent [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Stockholders’ Equity
	Redeemable Preferred Stock
	Pursuant to our charter, we are authorized to designate and issue up to 50.0 million shares of preferred stock in one or more classes or series. Our Board of Directors has designated 2.3 million shares as 8.125% Series A Cumulative Redeemable Preferred Stock ("Series A Preferred Stock"). As of March 31, 2015, we had 47.8 million of authorized but unissued shares of preferred stock. Shares of our Series A Preferred Stock are redeemable at $25.00 per share plus accumulated and unpaid dividends (whether or not declared) exclusively at our option commencing on May 22, 2019, or earlier under certain circumstances intended to preserve our qualification as a REIT for Federal income tax purposes. Dividends are payable quarterly in arrears on the 15th day of each January, April, July and October. As of March 31, 2015, we had declared all required quarterly dividends on the Series A Preferred Stock.
	Our Board of Directors may designate additional series of authorized preferred stock ranking junior to or in parity with
	the Series A Preferred Stock or designate additional shares of the Series A Preferred Stock and authorize the issuance of such
	shares.
	Common Stock Repurchase Program
	Our Board of Directors adopted a program that authorizes repurchases of our common stock through December 31, 2015,
	up to a specified amount. Shares of our common stock may be purchased in the open market, including through block purchases, or through privately negotiated transactions, or pursuant to any trading plan that may be adopted in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended. The timing, manner, price and amount of any repurchases will be determined at our discretion and the program may be suspended, terminated or modified at any time for any reason. Among other factors, we intend to only consider repurchasing shares of our common stock when the purchase price is less than our estimate of our current net asset value per common share. Generally, when we repurchase our common stock at a discount to our net asset value, the net asset value of our remaining shares of common stock outstanding increases. In addition, we do not intend to repurchase any shares from directors, officers or other affiliates. The program does not obligate us to acquire any specific number of shares, and all repurchases will be made in accordance with Rule 10b-18, which sets certain restrictions on the method, timing, price and volume of stock repurchases.
	We did not repurchase any shares of our common stock during the three months ended March 31, 2015. During the three months ended March 31, 2014, we repurchased approximately 0.2 million shares of our common stock at an average repurchase price of $19.67 per share, including expenses, totaling $4.2 million. As of March 31, 2015, we had an additional $134.9 million authorized for repurchases of our common stock through December 31, 2015.
	Long-Term Incentive Plan
	We sponsor the American Capital Mortgage Investment Corp. Amended and Restated Equity Incentive Plan ("Incentive Plan" or "plan") to provide for the issuance of equity-based awards, including stock options, restricted stock, restricted stock units ("RSU") and unrestricted stock. No shares were issued under the plan during the three months ended March 31, 2015. We issued 22,839 shares related to the time vesting of RSU awards during the year ended December 31, 2014.
	Net Income per Common Share
	Basic net income per common share is computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted net income per common share assumes the conversion, exercise or issuance of all potential common stock equivalents unless the effect is to reduce a loss or increase the income per share. Shares subject to performance conditions have been excluded from diluted net income per common share.
	The following summarizes the net income per common share for the three months ended March 31, 2015 and 2014 (in thousands, except per share data):
		For the Three Months Ended March 31,
		2015		2014
	Weighted average common shares calculation:
	Basic weighted average common shares outstanding	51,165		51,272
	Effect of stock based compensation	44		—
	Diluted weighted average common shares outstanding	51,209		51,272
	Net income	$	29,946	$	48,760
	Net income per common share — basic	$	0.59	$	0.95
	Net income per common share — diluted	$	0.58	$	0.95

Policies

(Policies)	3 Months Ended
	Mar. 31, 2015
Fair Value of Financial Assets [Abstract]
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value of Financial Assets
	We have elected the option to account for all of our financial assets, including all mortgage-related investments, at estimated fair value, with changes in fair value reflected in income during the period in which they occur. In management's view, this election more appropriately reflects the results of our operations for a particular reporting period, as financial asset fair value changes are presented in a manner consistent with the presentation and timing of the fair value changes of hedging instruments. See Note 9 - Fair Value Measurements.
Revenue Recognition, Policy [Policy Text Block]	Interest Income
	Interest income is accrued based on the outstanding principal amount of the securities and their contractual terms. Premiums or discounts associated with the purchase of agency RMBS and non-agency securities of high credit quality are amortized or accreted into interest income, respectively, over the projected lives of the securities, including contractual payments and estimated prepayments, using the effective interest method.
	We estimate long-term prepayment speeds using a third-party service and market data. The third-party service estimates prepayment speeds for our securities using models that incorporate the mortgage rates, age, size and loan-to-value ratios of the outstanding underlying loans, as well as current mortgage rates, forward yield curves, volatility and other factors. We review the prepayment speeds estimated by the third-party service and compare the results to market consensus prepayment speeds, if available. We also consider historical prepayment speeds and current market conditions to validate the reasonableness of the prepayment speeds estimated by the third-party service, and based on our Manager’s judgment, we may make adjustments to its estimates. Actual and anticipated prepayment experience is reviewed at least quarterly and effective yields are recalculated when differences arise between the previously estimated future prepayments and the amounts actually received plus currently anticipated future prepayments. If the actual and anticipated future prepayment experience differs from our prior estimate of prepayments, we are required to record an adjustment in the current period to the amortization or accretion of premiums and discounts for the cumulative difference in the effective yield through the reporting date.
	At the time we purchase non-agency securities and loans that are not of high credit quality, we determine an effective yield based on our estimate of the timing and amount of future cash flows and our cost basis. Our initial cash flow estimates for these investments are based on our observations of current information and events and include assumptions related to interest rates, prepayment rates and the impact of default and severity rates on the timing and amount of credit losses. On at least a quarterly basis, we review the estimated cash flows and make appropriate adjustments, based on inputs and analysis received from external sources, internal models, and our judgment about interest rates, prepayment rates, the timing and amount of credit losses, and other factors. Any resulting changes in effective yield are recognized prospectively based on the current amortized cost of the investment as adjusted for credit impairment, if any.
Transfers and Servicing of Financial Assets, Servicing of Financial Assets, Policy [Policy Text Block]	Mortgage Servicing Rights, at Fair Value
	Our MSR represent the right to service mortgage loans for a servicing fee. MSR are reported at fair value on our consolidated balance sheets, with changes in fair value related to changes in valuation inputs and assumptions reported as unrealized loss on MSR on the consolidated statements of operations. Servicing fees, incentive fees and ancillary income are reported within servicing income on the consolidated statements of operations. The related servicing expenses and realization of cash flows related to underlying loan repayments, net of recoveries of contractual prepayment protection, are recorded in servicing expenses on the consolidated statements of operations. See Note 10 - Mortgage Servicing Rights for further discussion on MSR.
	The accounting model used to evaluate whether a transfer of MSR qualifies as a sale is based on a risks and rewards approach, as MSR are not financial assets. In certain cases where we transfer the economics of MSR while retaining the actual servicing function, we retain the risk associated with servicing and, as a result, the transfer does not qualify for sale accounting. As such, we retain the MSR, together with an offsetting financing liability on our consolidated balance sheets. We have elected the option to account for MSR financing liabilities at estimated fair value, with changes in fair value reflected in income during the period in which they occur. See Note 12 - Accounts Payable and Other Accrued Liabilities for the presentations of our mortgage servicing liability.
	We may be obligated to fund advances of principal and interest payments due to third party loan investors prior to receiving payment on the loans from the individual borrowers. We may also be obligated to fund advances of real estate taxes and insurance, protective advances to preserve the value of the underlying property, and expenses associated with remedial action in respect of defaulted loans. These servicing advances are reported within other assets on the consolidated balance sheets.
Repurchase Agreements, Valuation, Policy [Policy Text Block]	Repurchase Agreements
	We finance the acquisition of agency RMBS and certain non-agency securities for our investment portfolio through repurchase transactions under master repurchase agreements. We account for repurchase transactions as collateralized financing transactions which are carried at their contractual amounts, including accrued interest, as specified in the respective transaction agreements. The contractual amounts approximate fair value due to their short-term nature.
Repurchase and Resale Agreements Policy [Policy Text Block]	Reverse Repurchase Agreements and Obligation to Return Securities Borrowed under Reverse Repurchase Agreements
	From time to time we borrow securities to cover short sales of U.S. Treasury securities through reverse repurchase transactions under our master repurchase agreements (see Derivatives below). We account for these as securities borrowing transactions and recognize an obligation to return the borrowed securities at fair value on the consolidated balance sheets based on the value of the underlying borrowed securities as of the reporting date. Our reverse repurchase agreements generally mature daily. The fair value of our reverse repurchase agreements is assumed to equal cost as the interest rates are reset daily.
Derivatives, Policy [Policy Text Block]	Derivatives
	We utilize a risk management strategy, under which we may use a variety of derivative instruments to hedge some of our exposure to market risks, including interest rate risk, prepayment risk, extension risk and credit risk. The objective of our risk management strategy is to reduce fluctuations in net book value over a range of market conditions. The principal instruments that we currently use are interest rate swaps and options to enter into interest rate swaps ("interest rate swaptions"). We also utilize forward contracts for the purchase or sale of agency RMBS, or to-be-announced forward ("TBA") contracts, and short sales of U.S. Treasury securities and U.S. Treasury futures contracts. We may also purchase or write put or call options on TBA securities and we may invest in other types of mortgage derivatives, such as synthetic total return swaps.
	We also enter into TBA contracts as a means of investing in and financing agency RMBS (thereby increasing our "at
	risk" leverage) or as a means of disposing of or reducing our exposure to agency RMBS (thereby reducing our "at risk" leverage). Pursuant to TBA contracts, we agree to purchase or sell, for future delivery, agency RMBS with certain principal and interest terms and certain types of collateral, but the particular agency RMBS to be delivered are not identified until shortly before the TBA settlement date. We may also choose, prior to settlement, to move the settlement of these securities out to a later date by entering into an offsetting short or long position (referred to as a "pair off"), net settling the paired off positions for cash, and simultaneously purchasing or selling a similar TBA contract for a later settlement date. This transaction is commonly referred to as a "dollar roll." The agency RMBS purchased or sold for a forward settlement date are typically priced at a discount to agency RMBS for settlement in the current month. This difference (or discount) is referred to as the "price drop." The price drop is the economic equivalent of net interest carry income on the underlying agency RMBS over the roll period (interest income less implied financing cost) and is commonly referred to as "dollar roll income (loss)." Consequently, forward purchases of agency RMBS and dollar roll transactions represent a form of off-balance sheet financing.
	We recognize all derivative instruments as either assets or liabilities on the balance sheets, measured at fair value. As we have not designated any derivatives as hedging instruments, all changes in fair value are reported in earnings in our consolidated statements of operations in unrealized gain (loss) on other derivatives and securities, net during the period in which they occur. Derivatives in a gain position are reported as derivative assets at fair value and derivatives in a loss position are reported as derivative liabilities at fair value in our consolidated balance sheets. Cash receipts and payments related to derivative instruments are classified in our consolidated statements of cash flows according to the underlying nature or purpose of the derivative transaction, generally in the investing section.
	Our derivative agreements generally contain provisions that allow for netting or setting off derivative assets and liabilities with each counterparty; however, we report related assets and liabilities on a gross basis in our consolidated balance sheets.
	The use of derivative instruments creates exposure to credit risk relating to potential losses that could be recognized in the event that the counterparties to these instruments fail to perform their obligations under the contracts. We attempt to minimize this risk by limiting our counterparties to major financial institutions with acceptable credit ratings, monitoring positions with individual counterparties and adjusting posted collateral as required.
	Interest rate swap agreements
	We use interest rate swaps to hedge the variable cash flows associated with short-term borrowings made under our repurchase agreement facilities. Under our interest rate swap agreements, we typically pay a fixed rate and receive a floating rate based on one, three or six-month LIBOR ("payer swaps") with terms up to 15 years. The floating rate we receive under our swap agreements has the effect of offsetting the repricing characteristics of our repurchase agreements and cash flows on such liabilities. Our swap agreements are privately negotiated in the over-the-counter ("OTC") market and may be centrally cleared through a registered commodities exchange ("centrally cleared swaps").
	We estimate the fair value of our centrally cleared interest rate swaps using the daily settlement price determined by the respective exchange. Centrally cleared swaps are valued by the exchange using a pricing model that references the underlying rates, including the overnight index swap rate and LIBOR forward rate, to produce the daily settlement price. We estimate the fair value of our "non-centrally cleared" interest rate swaps based on valuations obtained from third-party pricing services and the swap counterparty (collectively, “third-party valuations”). The third-party valuations are model-driven using observable inputs consisting of LIBOR and the forward yield curve. We also consider the creditworthiness of both us and our counterparties and the impact of netting and credit enhancement provisions contained in each derivative agreement, such as collateral postings. All of our "non-centrally cleared" interest rate swaps are subject to bilateral collateral arrangements. Consequently, no credit valuation adjustment was made in determining the fair value of such instruments.
	The payment of periodic settlements of net interest on interest rate swaps is reported in realized loss on periodic settlements of interest rate swaps, net in our consolidated statements of operations. Cash payments received or paid for the early termination of an interest rate swap agreement are recorded as realized gain (loss) on other derivatives and securities, net in our consolidated statements of operations. Changes in fair value of our interest rate swap agreements are reported in unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
	Interest rate swaptions
	We purchase interest rate swaptions to help mitigate the potential impact of larger, more rapid changes in interest rates
	on the performance of our investment portfolio. The interest rate swaptions provide us the option to enter into an interest rate swap agreement for a predetermined notional amount, stated term and pay or receive interest rates in the future. The premium paid for interest rate swaptions is reported as a derivative asset in our consolidated balance sheets. We estimate the fair value of interest rate swaptions based on the fair value of the future interest rate swap that we have the option to enter into as well as the remaining length of time that we have to exercise the option. The difference between the premium and the fair value of the swaption is reported in unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations. If a swaption expires unexercised, the realized loss on the swaption would be equal to the premium paid and reported in realized gain (loss) on other derivatives and securities, net in our consolidated statements of operations. If we exercise a swaption, the realized gain or loss on the swaption would be equal to the difference between the fair value of the underlying interest rate swap and the premium paid and reported in realized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
	Interest rate swaption agreements are privately negotiated in the OTC market and are not subject to central clearing. We estimate the fair value of our interest rate swaption agreements based on model-driven valuations obtained from third-party
	pricing services and the swaption counterparty. These estimates incorporate observable inputs and include the fair value of the future interest rate swaps that we have the option to enter into, as well as the remaining length of time that we have to exercise the options, adjusted for non-performance risk, if any.
	TBA securities
	A TBA security 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 stated maturity on an agreed-upon future date. The specific agency RMBS delivered into the contract upon the settlement date, published each month by the Securities Industry and Financial Markets Association, are not known at the time of the transaction. We may enter into TBA contracts as a means of hedging against short-term changes in interest rates. We may also enter into TBA contracts as a means of acquiring or disposing of agency RMBS and we may from time to time utilize TBA dollar roll transactions to finance agency RMBS purchases.
	We account for all TBA contracts as derivatives since we cannot assert that it is probable at the inception and throughout the term of the contract that it will not settle net and will result in physical delivery of an agency security when it is issued. A TBA dollar roll transaction is a series of derivative transactions. The net settlement of a TBA contract is reported as realized gain (loss) on other derivatives and securities, net and changes in the fair value of our TBA contracts are reported as unrealized gain (loss) on other derivatives and securities, net in our consolidated statements of operations.
	We estimate the fair value of TBA securities based on similar methods used to value our agency RMBS.
	Forward commitments to purchase or sell specified securities
	We may enter into a forward commitment to purchase or sell specified securities as a means of acquiring assets or as a hedge against short-term changes in interest rates. Such forward commitments usually require physical settlement. Contracts for the purchase or sale of specified securities are accounted for as derivatives if the delivery of the specified agency RMBS and settlement extends beyond established market conventions. Realized gains and losses associated with forward commitments are recognized in realized gain (loss) on other derivatives and securities, net and unrealized gains and losses are recognized in unrealized gain (loss) on other derivatives and securities, net on our consolidated statements of operations.
	We estimate the fair value of forward commitments to purchase or sell specified RMBS based on methods used to value our RMBS, as well as the remaining length of time of the forward commitment.
	U.S. Treasury securities
	We purchase or sell short U.S. Treasury securities and U.S. Treasury futures contracts to help mitigate the potential impact of changes in interest rates on the performance of our portfolio. Realized gains and losses associated with purchases and short sales of U.S. Treasury securities and U.S. Treasury futures contracts are recognized in realized gain (loss) on other derivatives and securities, net, and unrealized gains and losses are recognized in unrealized gain (loss) on other derivatives and securities, net on our consolidated statements of operations.

Agency_Securities_Tables

Agency Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Agency Securities [Abstract]
Agency Securities [Table Text Block]	The following tables summarize our investments in agency RMBS as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		March 31, 2015
		Fannie Mae				Freddie Mac				Total
	Agency RMBS:
	Par value	$	3,109,841			$	824,977			$	3,934,818
	Unamortized premium	149,456				41,537				190,993
	Amortized cost	3,259,297				866,514				4,125,811
	Gross unrealized gains	43,469				12,441				55,910
	Gross unrealized losses	(3,471		)		(1,901		)		(5,372		)
	Agency RMBS, at fair value	$	3,299,295			$	877,054			$	4,176,349
	Weighted average coupon as of March 31, 2015	3.41		%		3.51		%		3.43		%
	Weighted average yield as of March 31, 2015	2.54		%		2.64		%		2.56		%
	Weighted average yield for the three months ended March 31, 2015	2.46		%		2.52		%		2.47		%
			March 31, 2015
			Amortized Cost				Gross Unrealized Gain				Gross Unrealized Loss				Fair Value
	Agency RMBS:
	Fixed rate		$	4,009,298			$	51,305			$	(5,372	)		$	4,055,231
	Adjustable rate		116,513				4,605				—				121,118
	Total		$	4,125,811			$	55,910			$	(5,372	)		$	4,176,349
		31-Dec-14
		Fannie Mae				Freddie Mac				Total
	Agency RMBS:
	Par value	$	3,333,348			$	857,059			$	4,190,407
	Unamortized premium	141,252				43,070				184,322
	Amortized cost	3,474,600				900,129				4,374,729
	Gross unrealized gains	26,102				7,550				33,652
	Gross unrealized losses	(18,575		)		(5,667		)		(24,242		)
	Agency RMBS, at fair value	$	3,482,127			$	902,012			$	4,384,139
	Weighted average coupon as of December 31, 2014	3.37		%		3.5		%		3.39		%
	Weighted average yield as of December 31, 2014	2.54		%		2.65		%		2.56		%
	Weighted average yield for the year ended December 31, 2014	2.48		%		2.58		%		2.5		%
			31-Dec-14
			Amortized Cost				Gross Unrealized Gain				Gross Unrealized Loss				Fair Value
	Agency RMBS:
	Fixed rate		$	4,252,616			$	30,059			$	(24,242	)		$	4,258,433
	Adjustable rate		122,113				3,593				—				125,706
	Total		$	4,374,729			$	33,652			$	(24,242	)		$	4,384,139
Summary Of Agency Securities Estimated Weighted Average Life Classifications Text Block	The following table summarizes our agency RMBS as of March 31, 2015 and December 31, 2014 according to their estimated weighted average life classification (dollars in thousands):
		March 31, 2015														December 31, 2014
										Weighted Average												Weighted Average
	Weighted Average Life	Fair				Amortized				Yield			Coupon			Fair			Amortized			Yield		Coupon
		Value				Cost										Value			Cost
	Greater than three years and less than or equal to five years	1,525,807				1,501,583				2.19	%		3.08	%		1,528,121			1,520,350			2.13	%	3.05	%
	Greater than five years and less than or equal to 10 years	2,640,117				2,613,977				2.77	%		3.63	%		2,827,653			2,826,297			2.79	%	3.58	%
	Greater than 10 years	10,425				10,251				3.05	%		3.56	%		28,365			28,082			3.12	%	3.52	%
	Total	$	4,176,349			$	4,125,811			2.56	%		3.43	%		$	4,384,139		$	4,374,729		2.56	%	3.39	%
Schedule of Realized Gain (Loss) [Table Text Block]	The following table summarizes our net realized gains and losses from the sale of agency RMBS during the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015				2014
	Proceeds from agency RMBS sold		$	430,587			$	1,331,900
	Increase (decrease) in receivable for agency RMBS sold		351,759				(608,646		)
	Less agency RMBS sold, at cost		(781,412		)		(736,387		)
	Net realized gain (loss) on sale of agency RMBS		$	934			$	(13,133	)
	Gross realized gains on sale of agency RMBS		$	3,599			$	1,570
	Gross realized losses on sale of agency RMBS		(2,665		)		(14,703		)
	Net realized gain (loss) on sale of agency RMBS		$	934			$	(13,133	)
	The following table summarizes our net realized gains and losses from the sale of non-agency securities during the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015				2014
	Proceeds from non-agency securities sold		$	70,568			$	44,663
	Increase in receivable for non-agency RMBS sold		—				4,743
	Less: non-agency securities sold, at cost		(67,322		)		(47,997		)
	Net realized gain on sale of non-agency securities		$	3,246			$	1,409
	Gross realized gain on sale of non-agency securities		$	3,437			$	1,409
	Gross realized loss on sale of non-agency securities		(191		)		—
	Net realized gain on sale of non-agency securities		$	3,246			$	1,409
Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block]	The following tables summarize our agency RMBS pledged as collateral under repurchase agreements and derivative agreements by type as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015
	Agency RMBS Pledged (1)		Fannie Mae				Freddie Mac				Total
	Under Repurchase Agreements
	Fair value		$	3,236,201			$	871,850			$	4,108,051
	Accrued interest on pledged agency RMBS		8,678				2,397				11,075
	Under Derivative Agreements
	Fair value		5,312				372				5,684
	Accrued interest on pledged agency RMBS		14				1				15
	Total Fair Value of Agency RMBS Pledged and Accrued Interest		$	3,250,205			$	874,620			$	4,124,825
	————————
	-1	Agency RMBS pledged do not include pledged amounts of $344.7 million under repurchase agreements related to agency RMBS sold but not yet settled as of March 31, 2015.
			31-Dec-14
	Agency RMBS Pledged		Fannie Mae				Freddie Mac				Total
	Under Repurchase Agreements
	Fair value		$	3,395,257			$	838,627			$	4,233,884
	Accrued interest on pledged agency RMBS		9,089				2,335				11,424
	Under Derivative Agreements
	Fair value		677				674				1,351
	Accrued interest on pledged agency RMBS		2				2				4
	Total Fair Value of Agency RMBS Pledged and Accrued Interest		$	3,405,025			$	841,638			$	4,246,663
Schedules Of Securities Pledged As Collateral Under Repurchase Agreement [Text Block] [Table Text Block]	The following table summarizes our agency RMBS pledged as collateral under repurchase agreements by remaining maturity as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015												December 31, 2014
	Remaining Maturity		Fair Value				Amortized				Accrued Interest				Fair Value			Amortized			Accrued Interest
							Cost											Cost
	30 days or less		$	1,439,586			$	1,419,399			$	3,870			$	1,711,727		$	1,707,149		$	4,718
	31 - 59 days		977,026				962,258				2,619				507,160			503,833			1,310
	60 - 90 days		550,304				545,601				1,436				525,089			524,291			1,352
	Greater than 90 days		1,141,135				1,131,054				3,150				1,489,908			1,489,667			4,044
	Total		$	4,108,051			$	4,058,312			$	11,075			$	4,233,884		$	4,224,940		$	11,424
	The following table summarizes our non-agency securities pledged as collateral under repurchase agreements by remaining maturity as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015												December 31, 2014
	Remaining Maturity		Fair Value				Amortized				Accrued Interest				Fair Value			Amortized			Accrued Interest
							Cost											Cost
	30 days or less		$	916,555			$	876,284			$	1,307			$	791,654		$	770,604		$	1,151
	31 - 59 days		83,813				75,353				58				106,097			98,690			77
	60 - 90 days		41,940				38,119				40				43,230			39,280			40
	Total		$	1,042,308			$	989,756			$	1,405			$	940,981		$	908,574		$	1,268

NonAgency_Securities_Tables

Non-Agency Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Non-Agency Securities [Table Text Block]	The following tables summarize our non-agency securities as of March 31, 2015 and December 31, 2014 (dollars in thousands):
	March 31, 2015
			Fair			Gross Unrealized							Amortized Cost				Discount				Par/ Current Face				Weighted Average
	Category		Value			Gains			Losses																Coupon (1)			Yield
	Prime		$	213,629		$	8,724		$	(937	)		$	205,842			$	(23,678	)		$	229,520			3.3	%		5.35	%
	CRT		202,893			2,694			(4,166		)		204,365				4,617				199,748				4.3	%		5.56	%
	Alt-A		492,422			41,264			(4,407		)		455,565				(168,167		)		623,732				1.65	%		6.26	%
	Option-ARM		172,390			10,625			(3,145		)		164,910				(40,700		)		205,610				0.44	%		5.47	%
	Subprime		233,818			6,546			(129		)		227,401				(27,527		)		254,928				2.88	%		4.43	%
	Total		$	1,315,152		$	69,853		$	(12,784	)		$	1,258,083			$	(255,455	)		$	1,513,538			2.29	%		5.56	%
	————————
	-1	Coupon rates are floating, except for $15.9 million, $29.1 million and $172.5 million fair value of fixed-rate prime, Alt-A and subprime non-agency securities, respectively, as of March 31, 2015.
	31-Dec-14
			Fair			Gross Unrealized							Amortized Cost				Discount				Par/ Current Face				Weighted Average
	Category		Value			Gains			Losses																Coupon (1)			Yield
	Prime		$	178,215		$	11,346		$	(596	)		$	167,464			$	(25,977	)		$	193,441			3.03	%		6.42	%
	CRT		104,123			88			(5,893		)		109,929				4,150				105,779				4.21	%		5.46	%
	Alt-A		486,254			42,536			(4,090		)		447,808				(169,221		)		617,029				1.67	%		6.54	%
	Option-ARM		173,727			11,317			(2,473		)		164,883				(42,338		)		207,221				0.43	%		5.88	%
	Subprime		226,515			5,818			(342		)		221,039				(29,143		)		250,182				2.7	%		4.57	%
	Total		$	1,168,834		$	71,105		$	(13,394	)		$	1,111,123			$	(262,529	)		$	1,373,652			2.06	%		5.92	%
	————————
	-1	Coupon rates are floating, except for $2.5 million, $29.3 million and $151.2 million fair value of fixed-rate prime, Alt-A and subprime non-agency securities, respectively, as of December 31, 2014.
Schedule of Non-Agency Securities by Weighted Average Life [Table Text Block]	The following table summarizes our non-agency securities at fair value, by their estimated weighted average life classifications as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015												31-Dec-14
	Weighted Average Life		Fair Value			Amortized			Weighted			Weighted Average Coupon			Fair Value				Amortized				Weighted			Weighted Average Coupon
						Cost			Average										Cost				Average
									Yield														Yield
	≤ 5 years		$	444,160		$	432,651		4.86	%		2.95	%		$	436,385			$	422,400			5.15	%		2.85	%
	> 5 to ≤ 7 years		527,763			491,161			6.1	%		1.4	%		486,869				446,967				6.68	%		1.29	%
	> 7 years		343,229			334,271			5.68	%		3.05	%		245,580				241,756				5.89	%		2.43	%
	Total		$	1,315,152		$	1,258,083		5.56	%		2.29	%		$	1,168,834			$	1,111,123			5.92	%		2.06	%
Realized Gain (Loss) on Investments [Table Text Block]	The following table summarizes our net realized gains and losses from the sale of agency RMBS during the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Proceeds from agency RMBS sold		$	430,587		$	1,331,900
	Increase (decrease) in receivable for agency RMBS sold		351,759			(608,646		)
	Less agency RMBS sold, at cost		(781,412		)	(736,387		)
	Net realized gain (loss) on sale of agency RMBS		$	934		$	(13,133	)
	Gross realized gains on sale of agency RMBS		$	3,599		$	1,570
	Gross realized losses on sale of agency RMBS		(2,665		)	(14,703		)
	Net realized gain (loss) on sale of agency RMBS		$	934		$	(13,133	)
	The following table summarizes our net realized gains and losses from the sale of non-agency securities during the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Proceeds from non-agency securities sold		$	70,568		$	44,663
	Increase in receivable for non-agency RMBS sold		—			4,743
	Less: non-agency securities sold, at cost		(67,322		)	(47,997		)
	Net realized gain on sale of non-agency securities		$	3,246		$	1,409
	Gross realized gain on sale of non-agency securities		$	3,437		$	1,409
	Gross realized loss on sale of non-agency securities		(191		)	—
	Net realized gain on sale of non-agency securities		$	3,246		$	1,409
Schedules Of Securities Pledged As Collateral Under Repurchase Agreement [Text Block] [Table Text Block]	The following table summarizes our agency RMBS pledged as collateral under repurchase agreements by remaining maturity as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015										December 31, 2014
	Remaining Maturity		Fair Value			Amortized			Accrued Interest				Fair Value				Amortized				Accrued Interest
						Cost											Cost
	30 days or less		$	1,439,586		$	1,419,399		$	3,870			$	1,711,727			$	1,707,149			$	4,718
	31 - 59 days		977,026			962,258			2,619				507,160				503,833				1,310
	60 - 90 days		550,304			545,601			1,436				525,089				524,291				1,352
	Greater than 90 days		1,141,135			1,131,054			3,150				1,489,908				1,489,667				4,044
	Total		$	4,108,051		$	4,058,312		$	11,075			$	4,233,884			$	4,224,940			$	11,424
	The following table summarizes our non-agency securities pledged as collateral under repurchase agreements by remaining maturity as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015										December 31, 2014
	Remaining Maturity		Fair Value			Amortized			Accrued Interest				Fair Value				Amortized				Accrued Interest
						Cost											Cost
	30 days or less		$	916,555		$	876,284		$	1,307			$	791,654			$	770,604			$	1,151
	31 - 59 days		83,813			75,353			58				106,097				98,690				77
	60 - 90 days		41,940			38,119			40				43,230				39,280				40
	Total		$	1,042,308		$	989,756		$	1,405			$	940,981			$	908,574			$	1,268

Repurchase_Agreements_Tables

Repurchase Agreements (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Repurchase Agreements [Abstract]
Schedule of Debt [Table Text Block]	March 31, 2015 and December 31, 2014, our borrowings under repurchase agreements had the following collateral characteristics (dollars in thousands):
			March 31, 2015					December 31, 2014
					Weighted Average					Weighted Average
	Collateral Type		Borrowings		Interest Rate		Days	Borrowings		Interest Rate		Days
			Outstanding				to Maturity	Outstanding				to Maturity
	Agency securities (1)		$	4,203,338	0.42	%	213	$	4,002,291	0.42	%	245
	Non-agency securities		791,536		1.66	%	19	715,704		1.67	%	20
	U.S. Treasury securities		464,184		(0.03	)%	5	705,635		(0.13	)%	7
	Total repurchase agreements		$	5,459,058	0.56	%	167	$	5,423,630	0.51	%	190
	————————
	-1	Repurchase agreements borrowings secured by agency securities include $326.2 million of repurchase agreements related to agency RMBS sold but not yet settled as of March 31, 2015.
	The following table summarizes our borrowings under repurchase arrangements and weighted average interest rates classified by remaining maturities as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015					December 31, 2014
					Weighted Average					Weighted Average
			Borrowings		Interest Rate		Days	Borrowings		Interest Rate		Days
			Outstanding				to Maturity	Outstanding				to Maturity
	Agency and non-agency repurchase agreements
	≤ 1 month		$	2,151,856	0.78	%	14	$	2,245,188	0.71	%	13
	> 1 to ≤ 2 months		1,200,075		0.43	%	43	568,014		0.55	%	45
	> 2 to ≤ 3 months		569,598		0.49	%	82	540,201		0.48	%	74
	> 3 to ≤ 6 months		344,549		0.45	%	159	508,216		0.43	%	142
	> 6 to ≤ 9 months		213,796		0.52	%	237	123,947		0.51	%	246
	> 9 to ≤ 12 months		—		—	%	0	217,429		0.51	%	327
	> 12 months		515,000		0.65	%	1315	515,000		0.63	%	1405
	Total		4,994,874		0.62	%	183	4,717,995		0.61	%	210
	U.S. Treasury repurchase agreements
	Short-term		464,184		(0.03	)%	5	705,635		(0.13	)%	7
	Total repurchase agreements		$	5,459,058	0.56	%	167	$	5,423,630	0.51	%	190

Derivatives_Tables

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative [Line Items]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	The table below presents the balance sheet location and fair value information for our derivatives outstanding as of March 31, 2015 and December 31, 2014 (in thousands):
			31-Mar-15				31-Dec-14
	Interest rate swaps		$	466			$	9,414
	Interest rate swaptions		3,667				5,464
	TBA securities		9,272				13,495
	Interest only swaps		634				201
	Derivative assets, at fair value		$	14,039			$	28,574
	Interest rate swaps		$	106,059			$	73,052
	TBA securities		4,823				1,863
	Mortgage options		37				—
	U.S. Treasury futures		2,999				1,066
	Derivative liabilities, at fair value		$	113,918			$	75,981
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance [Table Text Block]	The following table summarizes the effect of our outstanding derivatives and other securities on our consolidated statements of operations during the three months ended March 31, 2015 and 2014 (in thousands):
			For the Three Months Ended March 31,
			2015										2014
			Realized Loss on Periodic Settlements of Interest Rate Swaps, net			Realized Gain (Loss) on Other Derivatives and Securities, net			Unrealized Gain (Loss) on Other Derivatives and Securities, net				Realized Loss on Periodic Settlements of Interest Rate Swaps, net			Realized Gain (Loss) on Other Derivatives and Securities, net			Unrealized Gain (Loss) on Other Derivatives and Securities, net
	Interest rate swaps		$	(4,311	)	$	(7,825	)	$	(43,106	)		$	(4,947	)	$	68		$	(28,164	)
	Interest rate swaptions		—			(520		)	(1,277		)		—			(14,668		)	(6,483		)
	TBA securities		—			16,436			(7,183		)		—			(8,829		)	(829		)
	U.S. Treasuries		—			15,901			2,655				—			1,047			10,958
	U.S. Treasury futures		—			(2,215		)	(1,933		)		—			(774		)	(2,238		)
	Short sales of U.S. Treasuries		—			(5,181		)	321				—			(1,547		)	3,820
	REIT equity investments		—			—			—				—			2,675			3,842
	Mortgage options		—			—			353				—			—			—
	Interest only swap		—			646			428				—			—			—
	Total		$	(4,311	)	$	17,242		$	(49,742	)		$	(4,947	)	$	(22,028	)	$	(19,094	)
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	The following tables summarize changes in notional amounts for our outstanding derivatives and other securities for the three months ended March 31, 2015 and 2014 (in thousands):
		31-Dec-14				Additions/ Long Positions			Expirations/			31-Mar-15
		Notional							Terminations/ Short Positions			Notional
		Amount										Amount
	Interest rate swaps	$	4,015,000			—			(600,000	)		$	3,415,000
	Interest rate swaptions	$	550,000			—			(100,000	)		$	450,000
	TBA securities	$	296,172			10,373,879			(10,407,731	)		$	262,320
	U.S. Treasuries	$	756,500			1,323,000			(1,558,000	)		$	521,500
	U.S. Treasury futures	$	(150,000	)		150,000			(150,000	)		$	(150,000	)
	Short sales of U.S. Treasuries	$	(228,500	)		364,000			(226,500	)		$	(91,000	)
	Mortgage options	$	—			—			(50,000	)		$	(50,000	)
	Interest only swaps	$	48,739			—			(2,238	)		$	46,501
		31-Dec-13				Additions/ Long Positions			Expirations/			31-Mar-14
		Notional							Terminations/ Short Positions			Notional
		Amount										Amount
	Interest rate swaps	$	3,240,000			850,000			(50,000	)		$	4,040,000
	Interest rate swaptions	$	2,100,000			—			(1,675,000	)		$	425,000
	TBA securities	$	(773,816	)		4,360,686			(2,912,089	)		$	674,781
	U.S. Treasuries	$	656,000			150,000			(681,000	)		$	125,000
	U.S. Treasury futures	$	(150,000	)		150,000			(150,000	)		$	(150,000	)
	Short sales of U.S. Treasuries	$	(23,000	)		48,000			(790,000	)		$	(765,000	)
Schedule Of Interest Rate Swap Agreement By Remaining Maturity [Table Text Block]	As of March 31, 2015 and December 31, 2014, we had interest rate swap agreements summarized in the tables below (dollars in thousands).
					31-Mar-15								31-Dec-14
	Interest Rate Swaps		Balance Sheet Location		Notional Amount				Fair Value				Notional Amount				Fair Value
	Interest rate swap assets		Derivative assets, at fair value		$	425,000			$	466			$	925,000			$	9,414
	Interest rate swap liabilities		Derivative liabilities, at fair value		2,990,000				(106,059		)		3,090,000				(73,052		)
					$	3,415,000			$	(105,593	)		$	4,015,000			$	(63,638	)
	March 31, 2015
			Notional				Fair Value				Weighted Average
			Amount
	Current Maturity Date for Interest Rate Swaps (1)										Fixed			Receive			Maturity
											Pay Rate (2)			Rate (3)			(Years)
	≤ 3 years		$	865,000			$	(3,973	)		1.01	%		0.26	%		1.7
	> 3 to ≤ 5 years		900,000				(16,208		)		1.94	%		0.26	%		4
	> 5 to ≤ 7 years		1,300,000				(63,589		)		2.86	%		0.26	%		6
	> 7 years		350,000				(21,823		)		2.78	%		0.26	%		8.3
	Total		$	3,415,000			$	(105,593	)		2.14	%		0.26	%		4.6
	December 31, 2014
			Notional				Fair Value				Weighted Average
	Current Maturity Date for Interest Rate Swaps (4)		Amount								Fixed			Receive			Maturity
											Pay Rate (2)			Rate (3)			(Years)
	≤ 3 years		$	1,065,000			$	(1,635	)		0.97	%		0.23	%		1.6
	> 3 to ≤ 5 years		850,000				(4,441		)		1.91	%		0.23	%		4.2
	> 5 to ≤ 7 years		1,625,000				(38,780		)		2.66	%		0.23	%		6
	> 7 years		475,000				(18,782		)		2.87	%		0.25	%		8.2
	Total		$	4,015,000			$	(63,638	)		2.08	%		0.23	%		4.7
	————————
	(1)	Includes swaps with an aggregate notional of $1.8 billion with deferred start dates averaging 0.9 years from March 31, 2015.
	(2)	Excluding forward starting swaps, the weighted average pay rate was 1.37% and 1.24% as of March 31, 2015 and December 31, 2014, respectively.
	(3)	Weighted average receive rate excludes impact of forward starting interest rate swaps.
	(4)	Includes swaps with an aggregate notional of $2.1 billion with deferred start dates averaging 1.1 years from December 31, 2014.
Schedule of Interest Rate Swaption Agreements Outstandin [Table Text Block]	The following tables present certain information about our interest rate swaption agreements as of March 31, 2015 and December 31, 2014 (dollars in thousands):
	March 31, 2015
			Option										Underlying Swap
	Current Option Expiration Date		Cost				Fair Value				Weighted Average Years to Expiration		Notional Amount				Pay Rate			Weighted Average Term (Years)
	> 3 to ≤ 12 months		$	6,631			$	2,219			0.6		$	250,000			3.23	%		8.7
	>12 to ≤ 24 months		1,308				82				1		100,000				4.13	%		7
	> 24 months		2,735				1,366				2.6		100,000				3.21	%		5
	Total / weighted average		$	10,674			$	3,667			1.2		$	450,000			3.43	%		7.5
	December 31, 2014
			Option										Underlying Swap
	Current Option Expiration Date		Cost				Fair Value				Weighted Average Years to Expiration		Notional Amount				Pay Rate			Weighted Average Term (Years)
	≤ 3 months		$	4,013			$	1,972			0.1		$	150,000			2.78	%		4.3
	> 3 to ≤ 12 months		3,139				1,432				0.9		200,000				3.29	%		8.8
	>12 to ≤ 24 months		1,308				207				1.3		100,000				4.13	%		7
	> 24 months		2,735				1,853				2.9		100,000				3.21	%		5
	Total / weighted average		$	11,195			$	5,464			1.1		$	550,000			3.29	%		6.5
Schedule of Long and Short Position of Derivative Instruments [Table Text Block]	TBA Securities
	As of March 31, 2015 and December 31, 2014, we had contracts to purchase ("long position") and sell ("short position") TBA securities on a forward basis, presented in the following table (in thousands):
			31-Mar-15								31-Dec-14
	Purchase and Sale Contracts for TBA Securities		Notional				Fair				Notional				Fair
			Amount (1)				Value (2)				Amount (1)				Value (2)
	TBA assets
	Purchase of TBA securities		$	745,898			$	9,272			$	829,030			$	8,226
	Sale of TBA securities		—				—				(74,758		)		5,269
	Total TBA assets		745,898				9,272				754,272				13,495
	TBA liabilities
	Purchase of TBA securities		297,930				(1,682		)		199,000				(595		)
	Sale of TBA securities		(781,508		)		(3,141		)		(657,100		)		(1,268		)
	Total TBA liabilities		(483,578		)		(4,823		)		(458,100		)		(1,863		)
	Total net TBA		$	262,320			$	4,449			$	296,172			$	11,632
	————————
	(1)	Notional amount represents the par value or principal balance of the underlying agency security.
	(2)	Fair value represents the current market value of the agency RMBS underlying the TBA contract as of period end, less the forward price to be paid for the underlying agency RMBS.

Offsetting_Assets_and_Liabilit1

Offsetting Assets and Liabilities Offsetting Financial and Derivative Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Offsetting of Financial Assets and Derivative Assets [Abstract]
Offsetting Assets [Table Text Block]	Offsetting of Financial Assets and Derivative Assets:
			Gross Amounts of Recognized Assets		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts Presented		Gross Amounts Not Offset in the Consolidated Balance Sheets
							in the Consolidated Balance Sheets		Financial Instruments			Collateral Received (1)			Net Amount
	March 31, 2015
	Interest rate swaps and swaptions (2)(3)		$	4,133	$	—	$	4,133	$	(1,296	)	$	(1,351	)	$	1,486
	Receivable under reverse repurchase agreements		70,636		—		70,636		(70,636		)	—			—
	Total		$	74,769	$	—	$	74,769	$	(71,932	)	$	(1,351	)	$	1,486
	December 31, 2014
	Interest rate swaps and swaptions (2)		$	14,878	$	—	$	14,878	$	(5,192	)	$	(3,059	)	$	6,627
	Receivable under reverse repurchase agreements		214,399		—		214,399		(214,399		)	—			—
	Total		$	229,277	$	—	$	229,277	$	(219,591	)	$	(3,059	)	$	6,627
Offsetting Liabilities [Table Text Block]	Offsetting of Financial Liabilities and Derivative Liabilities:
			Gross Amounts of Recognized Liabilities		Gross Amounts Offset in the Consolidated Balance Sheets		Net Amounts Presented		Gross Amounts Not Offset in the Consolidated Balance Sheets
							in the Consolidated Balance Sheets		Financial Instruments			Collateral Pledged (1)			Net Amount
	March 31, 2015
	Interest rate swaps (2)		$	106,059	$	—	$	106,059	$	(1,296	)	$	(104,763	)	$	—
	Repurchase agreements		5,459,058		—		5,459,058		(70,636		)	(5,388,422		)	—
	Total		$	5,565,117	$	—	$	5,565,117	$	(71,932	)	$	(5,493,185	)	$	—
	December 31, 2014
	Interest rate swaps (2)		$	73,052	$	—	$	73,052	$	(5,192	)	$	(67,860	)	$	—
	Repurchase agreements		5,423,630		—		5,423,630		(214,399		)	(5,209,231		)	—
	Total		$	5,496,682	$	—	$	5,496,682	$	(219,591	)	$	(5,277,091	)	$	—
	————————
	-1	Includes cash and securities received / pledged as collateral, at fair value. Amounts presented are limited to collateral pledged sufficient to reduce the net amount to zero on a counterparty by counterparty basis, as applicable. Refer to Notes 4 and 5 for additional information regarding assets pledged as collateral.
	-2	Reported under derivative assets / liabilities, at fair value in the accompanying consolidated balance sheets. Refer to Note 7 for a reconciliation of derivative assets / liabilities, at fair value to their sub-components.
	(3)	Interest rate swaps and swaptions are subject to master netting arrangements which could reduce our maximum amount of loss due to credit risk by $1.3 million as of March 31, 2015.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	The following tables present our financial instruments carried at fair value as of March 31, 2015 and December 31, 2014, on the consolidated balance sheets by the valuation hierarchy, as described above (in thousands):
			March 31, 2015
			Level 1			Level 2			Level 3			Total
	Assets
	Agency RMBS		$	—		$	4,176,349		$	—		$	4,176,349
	Non-agency securities		—			1,315,152			—			1,315,152
	U.S. Treasury securities		525,725			—			—			525,725
	Derivative assets		—			14,039			—			14,039
	MSR assets		—			—			87,811			87,811
	Total		$	525,725		$	5,505,540		$	87,811		$	6,119,076
	Liabilities
	Derivative liabilities		$	—		$	113,918		$	—		$	113,918
	Obligation to return securities borrowed under reverse repurchase agreements		91,159			—			—			91,159
	MSR financing liabilities		—			—			13,380			13,380
	Total		$	91,159		$	113,918		$	13,380		$	218,457
			December 31, 2014
			Level 1			Level 2			Level 3			Total
	Assets
	Agency RMBS		$	—		$	4,384,139		$	—		$	4,384,139
	Non-agency securities		—			1,168,834			—			1,168,834
	U.S. Treasury securities		758,629			—			—			758,629
	Derivative assets		—			28,574			—			28,574
	MSR assets		—			—			93,640			93,640
	Total		$	758,629		$	5,581,547		$	93,640		$	6,433,816
	Liabilities
	Derivative liabilities		$	—		$	75,981		$	—		$	75,981
	Obligation to return securities borrowed under reverse repurchase agreements		230,136			—			—			230,136
	MSR financing liabilities		—			—			14,003			14,003
	Total		$	230,136		$	75,981		$	14,003		$	320,120
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	The following table presents a summary of the changes in fair value for Level 3 assets carried at fair value for the three months ended March 31, 2015 and 2014 (in thousands):
			For the Three Months Ended March 31, 2015
			MSR Under Secured Financing (1)			Purchased MSR (2)			Total MSR
	Balance as of December 31, 2014		$	14,003		$	79,637		$	93,640
	Losses included in net income:
	Realized losses		(462		)	(2,413		)	(2,875		)
	Unrealized losses		(161		)	(3,194		)	(3,355		)
	Total net losses included in net income		(623		)	(5,607		)	(6,230		)
	Purchases, net of purchase price adjustments		—			401			401
	Balance as of March 31, 2015		$	13,380		$	74,431		$	87,811
			For the Three Months ended March 31, 2014
			MSR Under Secured Financing (1)			Purchased MSR (2)			Total MSR
	Balance as of December 31, 2013		$	15,608		$	—		$	15,608
	Losses included in net income:
	Realized losses		(202		)	(223		)	(425		)
	Unrealized losses		(31		)	(100		)	(131		)
	Total net losses included in net income		(233		)	(323		)	(556		)
	Purchases, net of purchase price adjustments		—			23,456			23,456
	Balance as of March 31, 2014		$	15,375		$	23,133		$	38,508
	————————
	-1	Losses included in net income related to MSR under secured financing are offset in their entirety by gains associated with related MSR financing liabilities.
	(2)	Realized losses of $(2.4) million and $(0.2) million on purchased MSR are included in servicing expense and unrealized losses of $(3.2) million and $(0.1) million are included in unrealized loss on mortgage servicing rights, respectively, on the consolidated statements of operations for the three months ended March 31, 2015 and 2014.
Fair Value Inputs, Assets, Quantitative Information [Table Text Block]	The following table presents the range of our estimates of loan constant voluntary prepayment rates and constant default rates, together with the discount rates used by third-party pricing providers in estimating the fair value of our Level 3 MSR as of March 31, 2015 (dollars in thousands):
			March 31, 2015
	Unobservable Level 3 Input		Fair Value			Minimum		Weighted	Maximum
								Average
	MSR treated as financing arrangements:		$	13,380
	Constant prepayment rate					5.60%		15.00%	33.20%
	Constant default rate					2.50%		7.60%	26.70%
	Discount rate					16.00%		16.00%	16.00%
	Purchased MSR:		74,431
	Constant prepayment rate					9.00%		9.10%	9.30%
	Constant default rate					0.20%		0.30%	0.40%
	Discount rate					8.30%		8.70%	9.30%
	Total		$	87,811

Mortgage_Servicing_Rights_Tabl

Mortgage Servicing Rights (Tables)	3 Months Ended
	Mar. 31, 2015
Servicing Assets at Fair Value [Line Items]
Schedule of Servicing Assets at Fair Value [Table Text Block]	The following table summarizes activity related to MSR accounted for as purchases during the three months ended March 31, 2015 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Beginning balance		$	79,637		$	—
	Additions from purchases of MSR		401			23,456
	Changes in fair value due to:
	Changes in valuation inputs or assumptions used in valuation model		(3,194		)	(100		)
	Other changes in fair value (1)		(2,413		)	(223		)
	Ending balance		$	74,431		$	23,133
	————————
	1	Other changes in fair value primarily represents changes due to the realization of cash flows.
Other Income and Other Expense Disclosure [Text Block]	The following table presents the components of net servicing loss for the three months ended March 31, 2015 and 2014 (dollars in thousands):
			For the Three Months Ended March 31,
			2015			2014
	Servicing fee income		$	7,948		$	5,823
	Incentive, ancillary and other income		3,856			3,741
	Servicing income		11,804			9,564
	Employee compensation and benefit costs		7,397			8,777
	Facility costs		2,828			2,933
	Realization of cash flows from MSR		2,413			223
	Other servicing costs		3,432			2,289
	Servicing expense		16,070			14,222
	Net servicing loss		$	(4,266	)	$	(4,658	)

Other_Assets_Tables

Other Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Other Assets [Abstract]
Schedule of Other Assets [Table Text Block]	The following table summarizes our other assets as of March 31, 2015 and December 31, 2014 (dollars in thousands):
		March 31, 2015			December 31, 2014
	Property and equipment, at cost	$	4,837		$	4,809
	Accumulated depreciation	(2,246		)	(1,877		)
	Net property and equipment	2,591			2,932
	Servicing advances	21,312			24,393
	Prepaid expenses	8,089			7,089
	Intangible assets	15,000			15,000
	Other	5,388			6,052
	Total other assets	$	52,380		$	55,466

Other_Liabilities_Tables

Other Liabilities (Tables)	3 Months Ended
	Mar. 31, 2015
Other Liabilities [Abstract]
Other Liabilities [Table Text Block]	The following table summarizes our accounts payable and other accrued liabilities as of March 31, 2015 and December 31, 2014 (dollars in thousands):
			March 31, 2015		December 31, 2014
	Cash collateral held on derivatives		$	1,351	$	2,298
	Due to manager		2,011		1,763
	Swaption premium payable		—		520
	Payable for MSR purchased		345		2,680
	Accrued interest		3,758		4,642
	Mortgage servicing financing, at fair value (1)		13,380		14,003
	Other accounts payable and accrued expenses		14,825		15,501
	Total accounts payable and other accrued liabilities		$	35,670	$	41,407
	——————
	-1	Mortgage servicing financing represents our obligations associated with excess MSR transferred to a third party which are accounted for as financing arrangements. We have elected the option to account for MSR financing at estimated fair value with changes in fair value reported in net income.

Stockholders_Equity_Tables

Stockholder's Equity (Tables)	3 Months Ended
	Mar. 31, 2015
Class of Stock [Line Items]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following summarizes the net income per common share for the three months ended March 31, 2015 and 2014 (in thousands, except per share data):
		For the Three Months Ended March 31,
		2015		2014
	Weighted average common shares calculation:
	Basic weighted average common shares outstanding	51,165		51,272
	Effect of stock based compensation	44		—
	Diluted weighted average common shares outstanding	51,209		51,272
	Net income	$	29,946	$	48,760
	Net income per common share — basic	$	0.59	$	0.95
	Net income per common share — diluted	$	0.58	$	0.95

Agency_Securities_Agency_secur

Agency Securities Agency securities, at fair value (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Agency Securities [Line Items]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	$4,176,349	$4,384,139
Agency Securities [Member]
Schedule of Agency Securities [Line Items]
Agency Securities at Par	3,934,818	4,190,407
Agency Securities Unamortized Premium	190,993	184,322
Agency Securities Amortized Cost	4,125,811	4,374,729
Agency Securities, Gross Unrealized Gains	55,910	33,652
Agency Securities, Gross Unrealized Losses	-5,372	-24,242
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	4,176,349	4,384,139
Weighted Average Coupon Rate	3.43%	3.39%
Weighted Average Yield Percentage	2.56%	2.56%
Weighted Average Yield Percentage for Period	2.47%	2.50%
Agency Securities [Member] | Fixed Rate Residential Mortgage [Member]
Schedule of Agency Securities [Line Items]
Agency Securities Amortized Cost	4,009,298	4,252,616
Agency Securities, Gross Unrealized Gains	51,305	30,059
Agency Securities, Gross Unrealized Losses	-5,372	-24,242
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	4,055,231	4,258,433
Agency Securities [Member] | Adjustable Rate Residential Mortgage [Member]
Schedule of Agency Securities [Line Items]
Agency Securities Amortized Cost	116,513	122,113
Agency Securities, Gross Unrealized Gains	4,605	3,593
Agency Securities, Gross Unrealized Losses	0	0
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	121,118	125,706
Agency Securities [Member] | Fannie Mae [Member]
Schedule of Agency Securities [Line Items]
Agency Securities at Par	3,109,841	3,333,348
Agency Securities Unamortized Premium	149,456	141,252
Agency Securities Amortized Cost	3,259,297	3,474,600
Agency Securities, Gross Unrealized Gains	43,469	26,102
Agency Securities, Gross Unrealized Losses	-3,471	-18,575
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	3,299,295	3,482,127
Weighted Average Coupon Rate	3.41%	3.37%
Weighted Average Yield Percentage	2.54%	2.54%
Weighted Average Yield Percentage for Period	2.46%	2.48%
Agency Securities [Member] | Freddie Mac [Member]
Schedule of Agency Securities [Line Items]
Agency Securities at Par	824,977	857,059
Agency Securities Unamortized Premium	41,537	43,070
Agency Securities Amortized Cost	866,514	900,129
Agency Securities, Gross Unrealized Gains	12,441	7,550
Agency Securities, Gross Unrealized Losses	-1,901	-5,667
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	$877,054	$902,012
Weighted Average Coupon Rate	3.51%	3.50%
Weighted Average Yield Percentage	2.64%	2.65%
Weighted Average Yield Percentage for Period	2.52%	2.58%

Agency_Securities_Weighted_Ave

Agency Securities Weighted Average Life of Agency Securities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	$4,176,349		$4,384,139
WeightedAverageLifeofAgencySecurities	6 years 6 months	6 years 9 months 0 days
Prepayment Rate Of Remaining Life Of Investment Portfolio	9.00%		8.00%
Agency Securities [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	4,176,349		4,384,139
Agency Securities Amortized Cost	4,125,811		4,374,729
Weighted Average Yield Percentage	2.56%		2.56%
Weighted Average Coupon Rate	3.43%		3.39%
Agency Securities [Member] | Greater Than Three Years and Less Than or Equal to Five Years [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	1,525,807		1,528,121
Agency Securities Amortized Cost	1,501,583		1,520,350
Weighted Average Yield Percentage	2.19%		2.13%
Weighted Average Coupon Rate	3.08%		3.05%
Agency Securities [Member] | Greater than 5 years and less than or equal to 10 years [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	2,640,117		2,827,653
Agency Securities Amortized Cost	2,613,977		2,826,297
Weighted Average Yield Percentage	2.77%		2.79%
Weighted Average Coupon Rate	3.63%		3.58%
Agency Securities [Member] | Greater than 10 years [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	10,425		28,365
Agency Securities Amortized Cost	$10,251		$28,082
Weighted Average Yield Percentage	3.05%		3.12%
Weighted Average Coupon Rate	3.56%		3.52%
Minimum [Member]
WeightedAverageLifeofAgencySecurities	3 years 5 months	3 years 2 months

Agency_Securities_Realized_Gai

Agency Securities Realized Gains and Losses on Agency Securities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Schedule of Agency Securities [Line Items]
Gain (Loss) on Sales of Mortgage Backed Securities (MBS)	$934	($13,133)
Agency Securities [Member]
Schedule of Agency Securities [Line Items]
Proceeds from Sale of Agency Securities, Debt	430,587	1,331,900
Increase (Decrease) in Other Receivables	351,759	-608,646
Cost of Sale of Agency Securities	-781,412	-736,387
Agency Securities, Gross Realized Gains	3,599	1,570
Agency Securities, Gross Realized Losses	-2,665	-14,703
Gain (Loss) on Sales of Mortgage Backed Securities (MBS)	$934	($13,133)

Recovered_Sheet1

Agency Securities Agency Securities Pledged Under Borrowing Agreements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Fair Value Of Agency Securities Pledged And Accrued Interest	$4,124,825,000	$4,246,663,000
Fannie Mae [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Fair Value Of Agency Securities Pledged And Accrued Interest	3,250,205,000	3,405,025,000
Freddie Mac [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Fair Value Of Agency Securities Pledged And Accrued Interest	874,620,000	841,638,000
Agency Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	4,113,735,000	4,235,235,000
Repurchase Agreements [Member] | Agency Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	4,108,051,000	4,233,884,000
Agency Securities Pledged As Collateral Accrued Interest	11,075,000	11,424,000
Repurchase Agreements [Member] | Agency Securities [Member] | Fannie Mae [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	3,236,201,000	3,395,257,000
Agency Securities Pledged As Collateral Accrued Interest	8,678,000	9,089,000
Repurchase Agreements [Member] | Agency Securities [Member] | Freddie Mac [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	871,850,000	838,627,000
Agency Securities Pledged As Collateral Accrued Interest	2,397,000	2,335,000
Under Derivative Agreements [Member] | Agency Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	5,684,000	1,351,000
Agency Securities Pledged As Collateral Accrued Interest	15,000	4,000
Under Derivative Agreements [Member] | Agency Securities [Member] | Fannie Mae [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	5,312,000	677,000
Agency Securities Pledged As Collateral Accrued Interest	14,000	2,000
Under Derivative Agreements [Member] | Agency Securities [Member] | Freddie Mac [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	372,000	674,000
Agency Securities Pledged As Collateral Accrued Interest	1,000	2,000
Agency Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateralized Agency Securities Sold But Not Settled	344,700,000
Agency Securities [Member] | Repurchase Agreements [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateralized Agency Securities Sold But Not Settled	$326,200,000

Agency_Securities_Agency_Secur1

Agency Securities Agency Securities Pledged As Collateral by Maturity Date (Details) (Agency Securities [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	$4,113,735	$4,235,235
Repurchase Agreements [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	4,108,051	4,233,884
Agency Securities Pledged As Collateral Amortized Cost	4,058,312	4,224,940
Pledged Assets, Not Separately Reported, Other	11,075	11,424
Repurchase Agreements [Member] | Maturity up to 30 days [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	1,439,586	1,711,727
Agency Securities Pledged As Collateral Amortized Cost	1,419,399	1,707,149
Pledged Assets, Not Separately Reported, Other	3,870	4,718
Repurchase Agreements [Member] | Maturity 31 To 59 Days [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	977,026	507,160
Agency Securities Pledged As Collateral Amortized Cost	962,258	503,833
Pledged Assets, Not Separately Reported, Other	2,619	1,310
Repurchase Agreements [Member] | Maturity 60 To 90 Days [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	550,304	525,089
Agency Securities Pledged As Collateral Amortized Cost	545,601	524,291
Pledged Assets, Not Separately Reported, Other	1,436	1,352
Repurchase Agreements [Member] | Maturity over 90 days [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Agency Securities Pledged As Collateral	1,141,135	1,489,908
Agency Securities Pledged As Collateral Amortized Cost	1,131,054	1,489,667
Pledged Assets, Not Separately Reported, Other	$3,150	$4,044

NonAgency_Securities_Schedule_

Non-Agency Securities Schedule of Non-Agency Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Narrative [Abstract]
Non-Agency Securities, at Fair Value	$1,315,152,000	$1,168,834,000
Prime [Member]
Non-Agency Security, at Fair Value	213,629,000	178,215,000
Gross Unrealized Gain on Non-Agency Securities	8,724,000	11,346,000
Gross Unrealized Loss on Non-Agency Securities	-937,000	-596,000
Non-Agency Securities, at Amortized Cost	205,842,000	167,464,000
Debt Instrument, Unamortized Discount	-23,678,000	-25,977,000
Non-Agency Securities at Par	229,520,000	193,441,000
Weighted Average Coupon Rate	3.30%	3.03%
Weighted Average Yield Percentage	5.35%	6.42%
Narrative [Abstract]
Fixed Rate Non-Agency Security	15,900,000	2,500,000
Credit Risk Transfer [Member]
Non-Agency Security, at Fair Value	202,893,000	104,123,000
Gross Unrealized Gain on Non-Agency Securities	2,694,000	88,000
Gross Unrealized Loss on Non-Agency Securities	-4,166,000	-5,893,000
Non-Agency Securities, at Amortized Cost	204,365,000	109,929,000
Debt Instrument, Unamortized Discount	4,617,000	4,150,000
Non-Agency Securities at Par	199,748,000	105,779,000
Weighted Average Coupon Rate	4.30%	4.21%
Weighted Average Yield Percentage	5.56%	5.46%
Alt-A [Member]
Non-Agency Security, at Fair Value	492,422,000	486,254,000
Gross Unrealized Gain on Non-Agency Securities	41,264,000	42,536,000
Gross Unrealized Loss on Non-Agency Securities	-4,407,000	-4,090,000
Non-Agency Securities, at Amortized Cost	455,565,000	447,808,000
Debt Instrument, Unamortized Discount	-168,167,000	-169,221,000
Non-Agency Securities at Par	623,732,000	617,029,000
Weighted Average Coupon Rate	1.65%	1.67%
Weighted Average Yield Percentage	6.26%	6.54%
Narrative [Abstract]
Fixed Rate Non-Agency Security	29,100,000	29,300,000
Option-Arm [Member]
Non-Agency Security, at Fair Value	172,390,000	173,727,000
Gross Unrealized Gain on Non-Agency Securities	10,625,000	11,317,000
Gross Unrealized Loss on Non-Agency Securities	-3,145,000	-2,473,000
Non-Agency Securities, at Amortized Cost	164,910,000	164,883,000
Debt Instrument, Unamortized Discount	-40,700,000	-42,338,000
Non-Agency Securities at Par	205,610,000	207,221,000
Weighted Average Coupon Rate	0.44%	0.43%
Weighted Average Yield Percentage	5.47%	5.88%
Subprime [Member]
Non-Agency Security, at Fair Value	233,818,000	226,515,000
Gross Unrealized Gain on Non-Agency Securities	6,546,000	5,818,000
Gross Unrealized Loss on Non-Agency Securities	-129,000	-342,000
Non-Agency Securities, at Amortized Cost	227,401,000	221,039,000
Debt Instrument, Unamortized Discount	-27,527,000	-29,143,000
Non-Agency Securities at Par	254,928,000	250,182,000
Weighted Average Coupon Rate	2.88%	2.70%
Weighted Average Yield Percentage	4.43%	4.57%
Narrative [Abstract]
Fixed Rate Non-Agency Security	172,500,000	151,200,000
Non-Agency Securities [Member]
Non-Agency Security, at Fair Value	1,315,152,000	1,168,834,000
Gross Unrealized Gain on Non-Agency Securities	69,853,000	71,105,000
Gross Unrealized Loss on Non-Agency Securities	-12,784,000	-13,394,000
Non-Agency Securities, at Amortized Cost	1,258,083,000	1,111,123,000
Debt Instrument, Unamortized Discount	-255,455,000	-262,529,000
Non-Agency Securities at Par	$1,513,538,000	$1,373,652,000
Weighted Average Coupon Rate	2.29%	2.06%
Weighted Average Yield Percentage	5.56%	5.92%
External Credit Rating, Non Investment Grade [Member]
Percentage of Non-Investment Grade Non-Agency Securities	99.00%
Minimum [Member] | Prime [Member]
Weighted Average Coupon Rate	0.77%
Underlying Collateral Coupon	2.38%
Minimum [Member] | Credit Risk Transfer [Member]
Weighted Average Coupon Rate	2.77%
Underlying Collateral Coupon	3.59%
Minimum [Member] | Alt-A [Member]
Weighted Average Coupon Rate	0.24%
Underlying Collateral Coupon	2.65%
Minimum [Member] | Option-Arm [Member]
Weighted Average Coupon Rate	0.31%
Underlying Collateral Coupon	2.73%
Maximum [Member] | Prime [Member]
Weighted Average Coupon Rate	6.50%
Underlying Collateral Coupon	5.76%
Maximum [Member] | Credit Risk Transfer [Member]
Weighted Average Coupon Rate	5.10%
Underlying Collateral Coupon	4.57%
Maximum [Member] | Alt-A [Member]
Weighted Average Coupon Rate	6.50%
Underlying Collateral Coupon	6.94%
Maximum [Member] | Option-Arm [Member]
Weighted Average Coupon Rate	1.03%
Underlying Collateral Coupon	3.96%

NonAgency_Securities_Weighted_

Non-Agency Securities Weighted Average Life of Non-Agency Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Non-Agency Securities, at Fair Value	$1,315,152	$1,168,834
Prime [Member]
Non-Agency Security, at Fair Value	213,629	178,215
Non-Agency Securities, at Amortized Cost	205,842	167,464
Weighted Average Yield Percentage	5.35%	6.42%
Weighted Average Coupon Rate	3.30%	3.03%
Prime [Member] | Pre-2010 [Member]
Non-Agency Security, at Fair Value	200,200
Alt-A [Member]
Non-Agency Security, at Fair Value	492,422	486,254
Non-Agency Securities, at Amortized Cost	455,565	447,808
Weighted Average Yield Percentage	6.26%	6.54%
Weighted Average Coupon Rate	1.65%	1.67%
Option-Arm [Member]
Non-Agency Security, at Fair Value	172,390	173,727
Non-Agency Securities, at Amortized Cost	164,910	164,883
Weighted Average Yield Percentage	5.47%	5.88%
Weighted Average Coupon Rate	0.44%	0.43%
Subprime [Member]
Non-Agency Security, at Fair Value	233,818	226,515
Non-Agency Securities, at Amortized Cost	227,401	221,039
Weighted Average Yield Percentage	4.43%	4.57%
Weighted Average Coupon Rate	2.88%	2.70%
Subprime [Member] | 2013 [Member]
Non-Agency Security, at Fair Value	119,500
Subprime [Member] | Pre-2013 [Member]
Non-Agency Security, at Fair Value	114,300
Non-Agency Securities [Member]
Non-Agency Security, at Fair Value	1,315,152	1,168,834
Non-Agency Securities, at Amortized Cost	1,258,083	1,111,123
Weighted Average Yield Percentage	5.56%	5.92%
Weighted Average Coupon Rate	2.29%	2.06%
Less Than or Equal to Five Years [Member]
Non-Agency Security, at Fair Value	444,160	436,385
Non-Agency Securities, at Amortized Cost	432,651	422,400
Weighted Average Yield Percentage	4.86%	5.15%
Weighted Average Coupon Rate	2.95%	2.85%
Greater Than Five Years and Less Than or Equal to Seven Year [Member]
Non-Agency Security, at Fair Value	527,763	486,869
Non-Agency Securities, at Amortized Cost	491,161	446,967
Weighted Average Yield Percentage	6.10%	6.68%
Weighted Average Coupon Rate	1.40%	1.29%
Greater Than Seven Years [Member]
Non-Agency Security, at Fair Value	343,229	245,580
Non-Agency Securities, at Amortized Cost	$334,271	$241,756
Weighted Average Yield Percentage	5.68%	5.89%
Weighted Average Coupon Rate	3.05%	2.43%
Minimum [Member] | Prime [Member]
Weighted Average Coupon Rate	0.77%
Underlying Collateral Coupon	2.38%
Minimum [Member] | Alt-A [Member]
Weighted Average Coupon Rate	0.24%
Underlying Collateral Coupon	2.65%
Minimum [Member] | Option-Arm [Member]
Weighted Average Coupon Rate	0.31%
Underlying Collateral Coupon	2.73%
Minimum [Member] | Subprime [Member] | 2013 [Member]
Weighted Average Coupon Rate	3.13%
Underlying Collateral Coupon	5.05%
Minimum [Member] | Subprime [Member] | Pre-2013 [Member]
Weighted Average Coupon Rate	0.23%
Underlying Collateral Coupon	4.42%
Maximum [Member] | Prime [Member]
Weighted Average Coupon Rate	6.50%
Underlying Collateral Coupon	5.76%
Maximum [Member] | Alt-A [Member]
Weighted Average Coupon Rate	6.50%
Underlying Collateral Coupon	6.94%
Maximum [Member] | Option-Arm [Member]
Weighted Average Coupon Rate	1.03%
Underlying Collateral Coupon	3.96%
Maximum [Member] | Subprime [Member] | 2013 [Member]
Weighted Average Coupon Rate	4.25%
Underlying Collateral Coupon	7.66%
Maximum [Member] | Subprime [Member] | Pre-2013 [Member]
Weighted Average Coupon Rate	5.29%
Underlying Collateral Coupon	5.92%

NonAgency_Securities_Realized_

Non-Agency Securities Realized Gains (Losses) from Sale of Non-Agency Securities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Gain (Loss) on Investments [Line Items]
Proceeds from sale of non-agency securities	$70,568	$44,663
Realized gain on non-agency securities, net	3,246	1,409
Non-Agency Securities [Member]
Gain (Loss) on Investments [Line Items]
Proceeds from sale of non-agency securities	-70,568	-44,663
Increase (Decrease) in Other Receivables	0	4,743
Cost of Sale of Non-Agency Securities	-67,322	-47,997
Available-for-sale Securities, Gross Realized Gains	-3,437	-1,409
Available-for-sale Securities, Gross Realized Losses	-191	0
Realized gain on non-agency securities, net	$3,246	$1,409

NonAgency_Securities_NonAgency

Non-Agency Securities Non-Agency Securities Pledged Under Repurchase Agreements (Details) (Non-Agency Securities [Member], Repurchase Agreements [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Short-term Debt [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$1,042,308	$940,981
Agency Securities Pledged As Collateral Amortized Cost	989,756	908,574
Pledged Assets, Not Separately Reported, Other	1,405	1,268
Maturity up to 30 days [Member]
Short-term Debt [Line Items]
Security Owned and Pledged as Collateral, Fair Value	916,555	791,654
Agency Securities Pledged As Collateral Amortized Cost	876,284	770,604
Pledged Assets, Not Separately Reported, Other	1,307	1,151
Maturity 31 To 59 Days [Member]
Short-term Debt [Line Items]
Security Owned and Pledged as Collateral, Fair Value	83,813	106,097
Agency Securities Pledged As Collateral Amortized Cost	75,353	98,690
Pledged Assets, Not Separately Reported, Other	58	77
Maturity 60 To 90 Days [Member]
Short-term Debt [Line Items]
Security Owned and Pledged as Collateral, Fair Value	41,940	43,230
Agency Securities Pledged As Collateral Amortized Cost	38,119	39,280
Pledged Assets, Not Separately Reported, Other	$40	$40

Repurchase_Agreements_Repurcha

Repurchase Agreements Repurchase Agreements by Collateral Type (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Securities Sold under Agreements to Repurchase	$5,459,058,000	$5,423,630,000
Short-term Debt, Weighted Average Interest Rate	0.56%	0.51%
Weighted Average Days to Maturity	167 days	190 days
Agency Securities [Member]
Short-term Debt [Line Items]
Securities Sold under Agreements to Repurchase	4,203,338,000	4,002,291,000
Short-term Debt, Weighted Average Interest Rate	0.42%	0.42%
Weighted Average Days to Maturity	213 days	245 days
Non-Agency Securities [Member]
Short-term Debt [Line Items]
Securities Sold under Agreements to Repurchase	791,536,000	715,704,000
Short-term Debt, Weighted Average Interest Rate	1.66%	1.67%
Weighted Average Days to Maturity	19 days	20 days
US Treasury Securities [Member]
Short-term Debt [Line Items]
Securities Sold under Agreements to Repurchase	464,184,000	705,635,000
Short-term Debt, Weighted Average Interest Rate	-0.03%	-0.13%
Weighted Average Days to Maturity	5 days	7 days
Agency Securities [Member]
Short-term Debt [Line Items]
Collateralized Agency Securities Sold But Not Settled	344,700,000
Repurchase Agreements [Member] | Agency Securities [Member]
Short-term Debt [Line Items]
Collateralized Agency Securities Sold But Not Settled	$326,200,000

Repurchase_Agreements_Schedule

Repurchase Agreements Schedule of Repurchase Agreements (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement [Line Items]
Securities Sold under Agreements to Repurchase	$5,459,058	$5,423,630
Short-term Debt, Weighted Average Interest Rate	0.56%	0.51%
Weighted Average Days to Maturity	167 days	190 days
Maturity up to 30 days [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	2,151,856	2,245,188
Short-term Debt, Weighted Average Interest Rate	0.78%	0.71%
Weighted Average Days to Maturity	14 days	13 days
Maturity Thirty One To Sixty Days [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	1,200,075	568,014
Short-term Debt, Weighted Average Interest Rate	0.43%	0.55%
Weighted Average Days to Maturity	43 days	45 days
Maturity 61 To 90 Days [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	569,598	540,201
Short-term Debt, Weighted Average Interest Rate	0.49%	0.48%
Weighted Average Days to Maturity	82 days	74 days
Maturity 90 to 180 Days [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	344,549	508,216
Short-term Debt, Weighted Average Interest Rate	0.45%	0.43%
Weighted Average Days to Maturity	159 days	142 days
Maturity 180 to 270 days [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	213,796	123,947
Short-term Debt, Weighted Average Interest Rate	0.52%	0.51%
Weighted Average Days to Maturity	237 days	246 days
Maturity 271 Days to 365 Days [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	0	217,429
Short-term Debt, Weighted Average Interest Rate	0.00%	0.51%
Weighted Average Days to Maturity	0 days	327 days
Greater Than 12 Months [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	515,000	515,000
Short-term Debt, Weighted Average Interest Rate	0.65%	0.63%
Weighted Average Days to Maturity	1315 days	1405 days
US Treasury Securities [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	464,184	705,635
Short-term Debt, Weighted Average Interest Rate	-0.03%	-0.13%
Weighted Average Days to Maturity	5 days	7 days
Agency and Non-Agency Securities [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	4,994,874	4,717,995
Short-term Debt, Weighted Average Interest Rate	0.62%	0.61%
Weighted Average Days to Maturity	183 days	210 days
Agency Securities [Member]
Statement [Line Items]
Securities Sold under Agreements to Repurchase	$4,203,338	$4,002,291
Short-term Debt, Weighted Average Interest Rate	0.42%	0.42%
Weighted Average Days to Maturity	213 days	245 days

Repurchase_Agreements_Repurcha1

Repurchase Agreements Repurchase Agreements Narrative (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Number of Repo Counterparties	$32	$31
Risk Of Repurchase Agreement To Stockholders Equity	5.00%
Secured Debt, Repurchase Agreements	5,459,058,000	5,423,630,000
Agency Securities [Member]
Agency Securities Pledged As Collateral	4,113,735,000	4,235,235,000
Repurchase Agreements [Member] | Agency Securities [Member]
Agency Securities Pledged As Collateral	4,108,051,000	4,233,884,000
Repurchase Agreements [Member] | Non-Agency Securities [Member]
Agency Securities Pledged As Collateral	1,042,308,000	940,981,000
Agency Securities [Member]
Collateralized Agreements	344,700,000
Agency Securities [Member] | Repurchase Agreements [Member]
Collateralized Agreements	$326,200,000
Top 5 Repo Counterparties [Member]
Risk Of Repurchase Agreement To Stockholders Equity	21.00%

Derivatives_Fair_Value_of_Outs

Derivatives Fair Value of Outstanding Derivatives (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative assets, at fair value	$14,039	$28,574
Derivative Liabilities	113,918	75,981
Interest Rate Swap Assets [Member]
Derivatives, Fair Value [Line Items]
Interest Rate Derivatives, at Fair Value, Net	-105,593		-63,638
Derivative assets, at fair value		9,414
Derivative Liabilities		73,052
Payer Swaption [Member]
Derivatives, Fair Value [Line Items]
Interest Rate Derivatives, at Fair Value, Net	3,667	5,464
Derivative assets, at fair value	3,667	5,464
Purchases Of TBAs And Forward Settling Agency Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, at fair value	9,272	13,495
Derivative Liabilities	4,823	1,863
Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, at fair value	634
Treasury Futures Short [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2,999	1,066
Assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amount of Recognized Assets (Liabilities)	74,769	229,277
Assets [Member] | Interest Rate Swap Assets [Member]
Derivatives, Fair Value [Line Items]
Interest Rate Derivatives, at Fair Value, Net	466		9,414
Derivative liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amount of Recognized Assets (Liabilities)	$106,059	$73,052

Derivatives_Effect_of_Derivati

Derivatives Effect of Derivatives on Net Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	($4,311)	($4,947)
Other realized gain loss on derivative instruments and other securities, net	17,242	-22,028
Unrealized Gain Loss On Derivative Instrument And Trading Securities	-49,742	-19,094
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	-4,311	-4,947
Other realized gain loss on derivative instruments and other securities, net	-7,825	68
Unrealized Gain Loss On Derivative Instrument And Trading Securities	-43,106	-28,164
Interest Rate Swaption [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	-520	-14,668
Unrealized Gain Loss On Derivative Instrument And Trading Securities	-1,277	-6,483
Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	16,436	-8,829
Unrealized Gain Loss On Derivative Instrument And Trading Securities	-7,183	-829
US Treasury Securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	15,901	1,047
Unrealized Gain Loss On Derivative Instrument And Trading Securities	2,655	10,958
Treasury Futures Short [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	-2,215	-774
Unrealized Gain Loss On Derivative Instrument And Trading Securities	-1,933	-2,238
Short Sales Of U S Government Securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	-5,181	-1,547
Unrealized Gain Loss On Derivative Instrument And Trading Securities	321	3,820
Equity Securities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	0	2,675
Unrealized Gain Loss On Derivative Instrument And Trading Securities	0	3,842
Call Option [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	0	0
Unrealized Gain Loss On Derivative Instrument And Trading Securities	353	0
Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain (loss) on periodic interest settlements of interest rate swaps, net	0	0
Other realized gain loss on derivative instruments and other securities, net	646	0
Unrealized Gain Loss On Derivative Instrument And Trading Securities	$428	$0

Derivatives_Change_in_Derivati

Derivatives Change in Derivative Notional Amounts (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Derivative [Line Items]
Notional Amount of Derivatives			$2,100,000
Notional Amount of Derivatives	1,800,000		2,100,000
Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	4,015,000	3,240,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	0	850,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-600,000	-50,000
Notional Amount of Derivatives	3,415,000	4,040,000
Interest Rate Swaption [Member]
Derivative [Line Items]
Notional Amount of Derivatives	550,000	2,100,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	0	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-100,000	-1,675,000
Notional Amount of Derivatives	450,000	425,000
Forward Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	296,172	-773,816
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	10,373,879	4,360,686
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-10,407,731	-2,912,089
Notional Amount of Derivatives	262,320	674,781
US Treasury Securities [Member]
Derivative [Line Items]
Notional Amount of Derivatives	756,500	656,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	1,323,000	150,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-1,558,000	-681,000
Notional Amount of Derivatives	521,500	125,000
Treasury Futures Short [Member]
Derivative [Line Items]
Notional Amount of Derivatives	-150,000	-150,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	150,000	150,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-150,000	-150,000
Notional Amount of Derivatives	-150,000	-150,000
Short Sales Of U S Government Securities [Member]
Derivative [Line Items]
Notional Amount of Derivatives	-228,500	-23,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	364,000	48,000
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-226,500	-790,000
Notional Amount of Derivatives	-91,000	-765,000
Call Option [Member]
Derivative [Line Items]
Notional Amount of Derivatives	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-50,000
Notional Amount of Derivatives	-50,000
Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	48,739
Notional Amount Of Derivatives Not Designated As Hedging Instruments Additions During The Period	0
Notional Amount Of Derivatives Not Designated As Hedging Instruments Settlement Expiration During The Period	-2,238
Notional Amount of Derivatives	$46,501

Derivatives_Interest_Rate_Swap

Derivatives Interest Rate Swap Agreements (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Notional Amount of Derivatives	$1,800,000	$2,100,000
Weighted Average Days to Maturity	167 days	190 days
Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	3,415,000	4,015,000	4,015,000
Interest Rate Derivatives, at Fair Value, Net	-105,593		-63,638
Weighted Average Days to Maturity	0 years 11 months	1 year 1 month
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-105,593	-63,638
Interest Rate Derivative Not Designated As Hedging Instruments Average Fixed Pay Rate	2.14%	2.08%
Interest Rate Derivative Not Designated As Hedging Instruments Average receive Rate	0.26%	0.23%
Derivative, Average Remaining Maturity	4 years 7 months	4 years 8 months
Assets [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	425,000		925,000
Interest Rate Derivatives, at Fair Value, Net	466		9,414
Liability [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,990,000		3,090,000
Interest Rate Derivatives, at Fair Value, Net	-106,059		-73,052
Greater Than One Year and Less Than or Equal to Three Years [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	865,000	1,065,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-3,973	-1,635
Interest Rate Derivative Not Designated As Hedging Instruments Average Fixed Pay Rate	1.01%	0.97%
Interest Rate Derivative Not Designated As Hedging Instruments Average receive Rate	0.26%	0.23%
Derivative, Average Remaining Maturity	1 year 8 months	1 year 7 months
Greater Than Three Years and Less Than or Equal to Five Years [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	900,000	850,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-16,208	-4,441
Interest Rate Derivative Not Designated As Hedging Instruments Average Fixed Pay Rate	1.94%	1.91%
Interest Rate Derivative Not Designated As Hedging Instruments Average receive Rate	0.26%	0.23%
Derivative, Average Remaining Maturity	4 years 0 months	4 years 2 months
Greater Than Five Years and Less than or Equal to Seven Years [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,300,000	1,625,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-63,589	-38,780
Interest Rate Derivative Not Designated As Hedging Instruments Average Fixed Pay Rate	2.86%	2.66%
Interest Rate Derivative Not Designated As Hedging Instruments Average receive Rate	0.26%	0.23%
Derivative, Average Remaining Maturity	6 years	6 years 0 months
Greater Than Seven Years and Less than or Equal to Ten Years [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	350,000	475,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-21,823	-18,782
Interest Rate Derivative Not Designated As Hedging Instruments Average Fixed Pay Rate	2.78%	2.87%
Interest Rate Derivative Not Designated As Hedging Instruments Average receive Rate	0.26%	0.25%
Derivative, Average Remaining Maturity	8 years 4 months	8 years 2 months
Maximum [Member]
Derivative [Line Items]
Percent of Equity at Risk Under Derivative Assets	1.00%
Exchange Cleared [Member] | Liability [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,100,000
Derivative Liability, Fair Value, Gross Liability	($98,000)

Derivatives_Interest_Rate_Swap1

Derivatives Interest Rate Swap by Remaining Maturity (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Notional Amount of Derivatives	$1,800,000	$2,100,000
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Variable Interest Rate	0.26%	0.23%
Notional Amount of Derivatives	3,415,000	4,015,000	4,015,000
Derivative, Forward Interest Rate	1.37%	1.24%
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-105,593	-63,638
Derivative, Average Fixed Interest Rate	2.14%	2.08%
Derivative, Average Remaining Maturity	4 years 7 months	4 years 8 months
Interest Rate Swap [Member] | Greater Than One Year and Less Than or Equal to Three Years [Member]
Derivative [Line Items]
Derivative, Variable Interest Rate	0.26%	0.23%
Notional Amount of Derivatives	865,000	1,065,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-3,973	-1,635
Derivative, Average Fixed Interest Rate	1.01%	0.97%
Derivative, Average Remaining Maturity	1 year 8 months	1 year 7 months
Interest Rate Swap [Member] | Greater Than Three Years and Less Than or Equal to Five Years [Member]
Derivative [Line Items]
Derivative, Variable Interest Rate	0.26%	0.23%
Notional Amount of Derivatives	900,000	850,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-16,208	-4,441
Derivative, Average Fixed Interest Rate	1.94%	1.91%
Derivative, Average Remaining Maturity	4 years 0 months	4 years 2 months
Interest Rate Swap [Member] | Greater Than Five Years and Less than or Equal to Seven Years [Member]
Derivative [Line Items]
Derivative, Variable Interest Rate	0.26%	0.23%
Notional Amount of Derivatives	1,300,000	1,625,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	-63,589	-38,780
Derivative, Average Fixed Interest Rate	2.86%	2.66%
Derivative, Average Remaining Maturity	6 years	6 years 0 months
Interest Rate Swap [Member] | Greater Than Seven Years and Less than or Equal to Ten Years [Member]
Derivative [Line Items]
Derivative, Variable Interest Rate	0.26%	0.25%
Notional Amount of Derivatives	350,000	475,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net	($21,823)	($18,782)
Derivative, Average Fixed Interest Rate	2.78%	2.87%
Derivative, Average Remaining Maturity	8 years 4 months	8 years 2 months

Derivatives_Interest_Rate_Swap2

Derivatives Interest Rate Swaptions (Details) (USD $)	12 Months Ended	3 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Options At Cost	$11,195
Weighted Average Years to Swaption Maturity	1 year 1 month
Notional Amount of Interest Rate Derivatives	2,100,000	1,800,000
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate	3.29%
Derivatives Average Term	6 years 6 months
Interest Rate Swaption [Member]
Derivative [Line Items]
Notional Amount of Interest Rate Derivatives	550,000	450,000	425,000	2,100,000
Interest Rate Swaption [Member]
Derivative [Line Items]
Options At Cost		10,674
Interest Rate Derivatives, at Fair Value, Net	5,464	3,667
Weighted Average Years to Swaption Maturity		1 year 2 months
Notional Amount of Interest Rate Derivatives	550,000	450,000
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate		3.43%
Derivatives Average Term		7 years 6 months
Greater Than 3 Months and Less Than 12 Months [Domain]
Derivative [Line Items]
Options At Cost	3,139
Weighted Average Years to Swaption Maturity	0 years 11 months
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate	3.29%
Derivatives Average Term	8 years 9 months
Greater Than 3 Months and Less Than 12 Months [Domain] | Interest Rate Swaption [Member]
Derivative [Line Items]
Options At Cost		6,631
Interest Rate Derivatives, at Fair Value, Net	1,432	2,219
Weighted Average Years to Swaption Maturity		0 years 7 months
Notional Amount of Interest Rate Derivatives	200,000	250,000
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate		3.23%
Derivatives Average Term		8 years 8 months
3 Months or Less [Member]
Derivative [Line Items]
Options At Cost	4,013
Weighted Average Years to Swaption Maturity	0 years 1 month 6 days
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate	2.78%
Derivatives Average Term	4 years 4 months
3 Months or Less [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Interest Rate Derivatives, at Fair Value, Net	1,972
Notional Amount of Interest Rate Derivatives	150,000
Greaterthan12Monthsandlessthanorequalto24Months [Member]
Derivative [Line Items]
Options At Cost	1,308
Weighted Average Years to Swaption Maturity	1 year 3 months
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate	4.13%
Derivatives Average Term	7 years 0 months
Greaterthan12Monthsandlessthanorequalto24Months [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Options At Cost		1,308
Interest Rate Derivatives, at Fair Value, Net	207	82
Weighted Average Years to Swaption Maturity		1 year 0 months
Notional Amount of Interest Rate Derivatives	100,000	100,000
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate		4.13%
Derivatives Average Term		7 years 0 months
Greater than 24 Months [Member]
Derivative [Line Items]
Options At Cost	2,735
Weighted Average Years to Swaption Maturity	2 years 11 months
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate	3.21%
Derivatives Average Term	5 years 0 months
Greater than 24 Months [Member] | Interest Rate Swaption [Member]
Derivative [Line Items]
Options At Cost		2,735
Interest Rate Derivatives, at Fair Value, Net	1,853	1,366
Weighted Average Years to Swaption Maturity		2 years 7 months
Notional Amount of Interest Rate Derivatives	$100,000	$100,000
Interest Rate Derivative Not Designated As Hedging instruments Pay Rate		3.21%
Derivatives Average Term		5 years 0 months

Derivatives_TBA_Securities_Det

Derivatives TBA Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]
Notional Amount of Derivatives	$1,800,000	$2,100,000
TBA securities Fifteen Year and Thirty Year Securities [Member]
Derivative [Line Items]
Notional Amount of Derivatives	262,320	296,172
Derivative, Fair Value, Net	4,449	11,632
Derivative Assets [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member]
Derivative [Line Items]
Notional Amount of Derivatives	745,898	754,272
Derivative, Fair Value, Net	9,272	13,495
Derivative Assets [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member] | Long [Member]
Derivative [Line Items]
Notional Amount of Derivatives	745,898	829,030
Derivative, Fair Value, Net	9,272	8,226
Derivative Assets [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member] | Short [Member]
Derivative [Line Items]
Notional Amount of Derivatives	0	-74,758
Derivative, Fair Value, Net	0	5,269
Derivative liabilities [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member]
Derivative [Line Items]
Notional Amount of Derivatives	-483,578	-458,100
Derivative, Fair Value, Net	-4,823	-1,863
Derivative liabilities [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member] | Long [Member]
Derivative [Line Items]
Notional Amount of Derivatives	297,930	199,000
Derivative, Fair Value, Net	-1,682	-595
Derivative liabilities [Member] | TBA securities Fifteen Year and Thirty Year Securities [Member] | Short [Member]
Derivative [Line Items]
Notional Amount of Derivatives	-781,508	-657,100
Derivative, Fair Value, Net	($3,141)	($1,268)

Derivatives_US_Treasury_Securi

Derivatives U.S. Treasury Securities and Futures (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Open Option Contracts Written [Line Items]
US Government Securities, at Carrying Value (including pledged securities of $460,333 and $571,145, respectively)	$525,725	$758,629
Notional Amount of Derivatives	1,800,000	2,100,000
Derivative Liabilities	113,918	75,981
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	91,159	230,136
Receivable Under Reverse Repurchase Agreements	70,636	214,399
US Treasury Securities [Member]
Open Option Contracts Written [Line Items]
Notional Amount of Derivatives	521,500	756,500	125,000	656,000
Treasury Futures Short [Member]
Open Option Contracts Written [Line Items]
Notional Amount of Derivatives	-150,000	-150,000	-150,000	-150,000
Derivative Liabilities	($3,000)	($1,100)

Derivatives_Credit_Risk_Contin

Derivatives Credit Risk Contingent Features (Details) (Maximum [Member])	Mar. 31, 2015
Maximum [Member]
Derivative [Line Items]
Percent of Equity at Risk Under Derivative Assets	1.00%

Offsetting_Assets_and_Liabilit2

Offsetting Assets and Liabilities Offsetting of Financial Assets and Liabilities (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$1,300,000
Derivative Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross Amount of Recognized Assets (Liabilities)	4,133,000	14,878,000
Gross Amounts Offset on the Balance Sheet	0	0
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	4,133,000	14,878,000
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-1,296,000	-5,192,000
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-1,351,000	-3,059,000
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	1,486,000	6,627,000
Securities Sold under Agreements to Repurchase [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross Amount of Recognized Assets (Liabilities)	70,636,000	214,399,000
Gross Amounts Offset on the Balance Sheet	0	0
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	70,636,000	214,399,000
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-70,636,000	-214,399,000
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	0	0
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	0	0
Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross Amount of Recognized Assets (Liabilities)	74,769,000	229,277,000
Gross Amounts Offset on the Balance Sheet	0	0
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	74,769,000	229,277,000
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-71,932,000	-219,591,000
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-1,351,000	-3,059,000
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	1,486,000	6,627,000
Derivative liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross Amount of Recognized Assets (Liabilities)	106,059,000	73,052,000
Gross Amounts Offset on the Balance Sheet	0	0
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	106,059,000	73,052,000
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-1,296,000	-5,192,000
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-104,763,000	-67,860,000
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	0	0
Repurchase Agreements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross Amount of Recognized Assets (Liabilities)	5,459,058,000	5,423,630,000
Gross Amounts Offset on the Balance Sheet	0	0
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	5,459,058,000	5,423,630,000
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-70,636,000	-214,399,000
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-5,388,422,000	-5,209,231,000
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	0	0
Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross Amount of Recognized Assets (Liabilities)	5,565,117,000	5,496,682,000
Gross Amounts Offset on the Balance Sheet	0	0
Net Amount of Assets (Liabilities) Presented on the Balance Sheet	5,565,117,000	5,496,682,000
Gross Amounts of Financial Instruments Not Offset on the Balance Sheet	-71,932,000	-219,591,000
Gross Amounts of Cash Collateral Not Offset on the Balance Sheet	-5,493,185,000	-5,277,091,000
Net Amount After Deducting Gross Amounts Not Offset on the Balance Sheet From Net Amount of Assets (Liabilities) Presented on the Balance Sheet	$0	$0

Fair_Value_Measurements_Financ

Fair Value Measurements Financial Instruments Measured on a Recurring Basis (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	$4,176,349	$4,384,139
US Government Securities, at Carrying Value (including pledged securities of $460,333 and $571,145, respectively)	-525,725	-758,629
Derivative Asset	14,039	28,574
Servicing Asset at Fair Value, Amount	87,800
Derivative liabilities, at fair value	113,918	75,981
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	91,159	230,136
Servicing Liability	13,380	14,003
Fair Value, Measurements, Recurring [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	4,176,349	4,384,139
Non-Agency Security, at Fair Value	1,315,152	1,168,834
US Government Securities, at Carrying Value (including pledged securities of $460,333 and $571,145, respectively)	-525,725	-758,629
Derivative Asset	14,039	28,574
Servicing Asset at Fair Value, Amount	87,811	93,640
Assets, Fair Value Disclosure, Recurring	6,119,076	6,433,816
Derivative liabilities, at fair value	113,918	75,981
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	91,159	230,136
Servicing Liability	13,380	14,003
Liabilities, Fair Value Disclosure, Recurring	218,457	320,120
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	0	0
Non-Agency Security, at Fair Value	0	0
US Government Securities, at Carrying Value (including pledged securities of $460,333 and $571,145, respectively)	-525,725	-758,629
Derivative Asset	0	0
Servicing Asset at Fair Value, Amount	0	0
Assets, Fair Value Disclosure, Recurring	525,725	758,629
Derivative liabilities, at fair value	0	0
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	91,159	230,136
Servicing Liability	0	0
Liabilities, Fair Value Disclosure, Recurring	91,159	230,136
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	4,176,349	4,384,139
Non-Agency Security, at Fair Value	1,315,152	1,168,834
US Government Securities, at Carrying Value (including pledged securities of $460,333 and $571,145, respectively)	0	0
Derivative Asset	14,039	28,574
Servicing Asset at Fair Value, Amount	0	0
Assets, Fair Value Disclosure, Recurring	5,505,540	5,581,547
Derivative liabilities, at fair value	113,918	75,981
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	0	0
Servicing Liability	0	0
Liabilities, Fair Value Disclosure, Recurring	113,918	75,981
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Owned, Mortgages, Mortgage-backed and Asset-backed Securities, at Fair Value	0	0
Non-Agency Security, at Fair Value	0	0
US Government Securities, at Carrying Value (including pledged securities of $460,333 and $571,145, respectively)	0	0
Derivative Asset	0	0
Servicing Asset at Fair Value, Amount	87,811	93,640
Assets, Fair Value Disclosure, Recurring	87,811	93,640
Derivative liabilities, at fair value	0	0
Obligation to Return Securities Borrowed Under Reverse Repurchase Agreements at Fair Value	0	0
Servicing Liability	13,380	14,003
Liabilities, Fair Value Disclosure, Recurring	$13,380	$14,003

Fair_Value_Measurements_Level_

Fair Value Measurements Level 3 Financial Assets and Liabilities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortization of Mortgage Servicing Rights (MSRs)	($2,413)	($223)
Unrealized gain (loss) mortgage servicing rights	-3,194	-100
Other Operating Income (Expense), Net	-4,266	-4,658
Purchased MSR [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Amortization of Mortgage Servicing Rights (MSRs)	2,413	223
Unrealized gain (loss) mortgage servicing rights	-3,194	-100
Fair Value, Inputs, Level 3 [Member] | Servicing Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	87,811	38,508	93,640	15,608
Amortization of Mortgage Servicing Rights (MSRs)	-2,875	-425
Unrealized gain (loss) mortgage servicing rights	-3,355	-131
Other Operating Income (Expense), Net	-6,230	-556
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	401	23,456
Fair Value, Inputs, Level 3 [Member] | Servicing Contracts [Member] | MSR Treated as Financing Arrangement [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	13,380	15,375	14,003	15,608
Amortization of Mortgage Servicing Rights (MSRs)	-462	-202
Unrealized gain (loss) mortgage servicing rights	-161	-31
Other Operating Income (Expense), Net	-623	-233
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0	0
Fair Value, Inputs, Level 3 [Member] | Servicing Contracts [Member] | Purchased MSR [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	74,431	23,133	79,637	0
Amortization of Mortgage Servicing Rights (MSRs)	-2,413	-223
Unrealized gain (loss) mortgage servicing rights	-3,194	-100
Other Operating Income (Expense), Net	-5,607	-323
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	$401	$23,456

Fair_Value_Measurements_Level_1

Fair Value Measurements Level 3 Unobservable Inputs (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Servicing Asset at Fair Value, Amount	$87,800
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Servicing Asset at Fair Value, Amount	87,811	93,640
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Servicing Asset at Fair Value, Amount	87,811	93,640
MSR Treated as Financing Arrangement [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Servicing Asset at Fair Value, Amount	13,380
MSR Treated as Financing Arrangement [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Constant Prepayment Speed	5.60%
Loss Severity	2.50%
Discount Rate	16.00%
MSR Treated as Financing Arrangement [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Constant Prepayment Speed	15.00%
Loss Severity	7.60%
Discount Rate	16.00%
MSR Treated as Financing Arrangement [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Constant Prepayment Speed	33.20%
Loss Severity	26.70%
Discount Rate	16.00%
Purchased MSR [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Servicing Asset at Fair Value, Amount	74,431	79,637	23,133	0
Purchased MSR [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Constant Prepayment Speed	9.00%
Loss Severity	0.20%
Discount Rate	8.30%
Purchased MSR [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Constant Prepayment Speed	9.10%
Loss Severity	0.30%
Discount Rate	8.70%
Purchased MSR [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Constant Prepayment Speed	9.30%
Loss Severity	0.40%
Discount Rate	9.30%
Servicing Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	87,811	93,640	38,508	15,608
Servicing Contracts [Member] | MSR Treated as Financing Arrangement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	13,380	14,003	15,375	15,608
Servicing Contracts [Member] | Purchased MSR [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$74,431	$79,637	$23,133	$0

Mortgage_Servicing_Rights_Deta

Mortgage Servicing Rights (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Servicing Asset at Fair Value, Amount	$87,800,000
MSR Treated as Financing Arrangement [Member]
Servicing Asset at Fair Value, Amount	13,380,000
Purchased MSR [Member]
Mortgage Servicing Rights, Number of Loans	33,000
Mortgage Servicing Rights, Unpaid Principal	6,900,000,000
Servicing Asset at Fair Value, Amount	$74,431,000	$79,637,000	$23,133,000	$0

Mortgage_Servicing_Rights_Roll

Mortgage Servicing Rights Rollforward of Mortgage Servicing Rights (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Servicing Assets at Fair Value [Line Items]
Servicing Asset at Fair Value, Amount	$87,800
Servicing Asset at Fair Value, Additions	-2,736	-20,588
Unrealized gain (loss) mortgage servicing rights	-3,194	-100
Amortization of Mortgage Servicing Rights (MSRs)	2,413	223
Purchased MSR [Member]
Servicing Assets at Fair Value [Line Items]
Servicing Asset at Fair Value, Amount	74,431	23,133	79,637	0
Servicing Asset at Fair Value, Additions	401	23,456
Unrealized gain (loss) mortgage servicing rights	-3,194	-100
Amortization of Mortgage Servicing Rights (MSRs)	($2,413)	($223)

Mortgage_Servicing_Rights_Comp

Mortgage Servicing Rights Components of Servicing Revenue and Expense (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Components of Servicing Revenue [Line Items]
Contractually Specified Servicing Fees, Amount	$7,948	$5,823
Ancillary Fee Income Generated by Servicing Financial Assets, Amount	3,856	3,741
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	11,804	9,564
Labor and Related Expense	7,397	8,777
Occupancy, Net	2,828	2,933
Amortization of Mortgage Servicing Rights (MSRs)	-2,413	-223
Other Expenses	3,432	2,289
Other Noninterest Expense	16,070	14,222
Other Operating Income (Expense), Net	($4,266)	($4,658)

Other_Assets_Schedule_of_Other

Other Assets Schedule of Other Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Other Assets [Line Items]
Property, Plant and Equipment, Gross	$4,837	$4,809
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	-2,246	-1,877
Property, Plant and Equipment, Net	2,591	2,932
Other Receivables	21,312	24,393
Prepaid Expense, Current	8,089	7,089
Goodwill	15,000	15,000
Other Assets, Miscellaneous, Current	5,388	6,052
Other Assets	$52,380	$55,466

Other_Liabilities_Schedule_of_

Other Liabilities Schedule of Other Liabilities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative, Collateral, Obligation to Return Cash	$1,351	$2,298
Due to Affiliate, Current	2,011	1,763
Other Payables to Broker-Dealers and Clearing Organizations	0	520
Other Accrued Liabilities, Current	345	2,680
Interest Payable, Current	3,758	4,642
Servicing Liability	13,380	14,003
Other Accounts Payable and Accrued Liabilities	14,825	15,501
Accounts Payable and Accrued Liabilities	$35,670	$41,407

Stockholders_Equity_Preferred_

Stockholder's Equity Preferred Stock Offering (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 31, 2015
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Preferred Class A [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	2,300,000
Preferred Stock, Dividend Rate, Percentage	8.13%
Preferred Stock, Shares Subscribed but Unissued	47,800,000
Preferred Stock, Redemption Price Per Share	$25

Stockholders_Equity_Stock_Repu

Stockholder's Equity Stock Repurchase Program (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2015
Class of Stock [Line Items]
Stock Repurchased During Period, Shares	0.2
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$134.90
Treasury Stock Acquired, Average Cost Per Share	$19.67
Stock Repurchased During Period, Value	$4.20

Stockholders_Equity_Long_Term_

Stockholder's Equity Long Term Incentive Plan (Details) (Restricted Stock Units (RSUs) [Member], Management [Member])	Dec. 31, 2014
Restricted Stock Units (RSUs) [Member] | Management [Member]
Class of Stock [Line Items]
Shares, Issued	22,839

Stockholders_Equity_Earnings_p

Stockholder's Equity Earnings per Share (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted Average Number of Shares Outstanding, Basic	51,165	51,272
Weighted Average Number Diluted Shares Outstanding Adjustment	44	0
Weighted Average Number of Shares Outstanding, Diluted	51,209	51,272
Net Income (Loss) Available to Common Stockholders, Basic	$29,946	$48,760
Earnings Per Share, Basic	$0.59	$0.95
Earnings Per Share, Diluted	$0.58	$0.95