CYS Investments 10-Q 24 Apr 15 2015 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 23, 2015
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2015
Entity Registrant Name	CYS Investments, Inc.
Entity Central Index Key	1396446
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		158,135,786

Consolidated_Statements_Of_Ass

Consolidated Statements Of Assets And Liabilities (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets:
Investments in securities, at fair value (including pledged assets of $11,309,980 and $11,908,922, respectively)	$15,065,303	$14,609,532	[1]
Derivative assets, at fair value	91,604	148,284	[1]
Cash	7,170	4,323	[1]
Receivable for securities sold and principal repayments	345,006	83,643	[1]
Interest receivable	37,314	37,894	[1]
Receivable for cash pledged as collateral	37,216	11,104	[1]
Other assets	11,408	1,083	[1]
Total assets	15,595,021	14,895,863	[1]
Liabilities:
Repurchase agreements	10,204,901	11,289,559	[1]
FHLB advances	510,000	0	[1]
Derivative liabilities, at fair value	38,502	16,007	[1]
Payable for securities purchased	2,767,042	1,505,481	[1]
Payable for cash received as collateral	48,229	72,771	[1]
Distribution payable	51,844	4,410	[1]
Accrued interest payable (including accrued interest on repurchase agreements and FHLB advances of $3,574 and $5,334, respectively)	31,422	27,208	[1]
Accrued expenses and other liabilities	2,445	5,259	[1]
Total liabilities	13,654,385	12,920,695	[1]
Stockholders' equity:
7.75% Series A Cumulative Redeemable Preferred Stock, (3,000 shares issued and outstanding, respectively, $75,000 in aggregate liquidation preference)	72,369	72,369	[1]
7.50% Series B Cumulative Redeemable Preferred Stock, (8,000 shares issued and outstanding, respectively, $200,000 in aggregate liquidation preference)	193,531	193,531	[1]
Common Stock, $0.01 par value, 500,000 shares authorized (158,114 and 161,850 shares issued and outstanding, respectively)	1,581	1,618	[1]
Additional paid in capital	2,012,697	2,049,152	[1]
Accumulated deficit	-339,542	-341,502	[1]
Total stockholders' equity	1,940,636	1,975,168	[1]
Total liabilities and stockholders' equity	$15,595,021	$14,895,863	[1]
[1]	Derived from audited financial statements.

Condolidated_Statements_Of_Ass

Condolidated Statements Of Assets And Liabilities (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Investments in securities, pledged assets	$11,309,980	$11,908,922
Accrued interest payable, accrued interest on repurchase agreements	3,574	5,334
Series Cumulative Redeemable Preferred Stock, par value	$0.01	$0.01
Preferred Stock, shares authorized	50,000,000	50,000,000
Series A Cumulative Redeemable Preferred Stock, shares issued	3,000,000	3,000,000
Series A Cumulative Redeemable Preferred Stock, shares outstanding	3,000,000	3,000,000
Series A Cumulative Redeemable Preferred Stock, aggregate liquidation value	75,000	75,000
Series A Cumulative Redeemable Preferred Stock, liquidation preference per share	$25	$25
Series B Cumulative Redeemable Preferred Stock, shares issued	8,000,000	8,000,000
Series B Cumulative Redeemable Preferred Stock, shares outstanding	8,000,000	8,000,000
Series B Cumulative Redeemable Preferred Stock, aggregate liquidation value	$200,000	$200,000
Series B Cumulative Redeemable Preferred Stock, liquidation preference per share	$25	$25
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	158,114,483	161,849,878
Common stock, shares outstanding	158,114,483	161,849,878

Condensed_Statements_Of_Operat

Condensed Statements Of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest income:
Interest income from Agency RMBS	$80,060	$80,186
Other interest income	790	4,181
Total interest income	80,850	84,367
Interest expense:
Repurchase agreement and FHLB advances interest expense	9,642	9,423
Swap and cap interest expense	27,468	18,923
Total interest expense	37,110	28,346
Net interest income	43,740	56,021
Other income (loss):
Net realized gain (loss) on investments	18,253	16,670
Net unrealized gain (loss) on investments	75,689	89,234
Net realized gain (loss) on termination of swap and cap contracts	-2,568	-9,323
Net unrealized gain (loss) on swap and cap contracts	-74,800	-16,240
Other income	40	119
Total other income (loss)	16,614	80,460
Expenses:
Compensation and benefits	3,554	3,629
General, administrative and other	2,203	2,165
Total expenses	5,757	5,794
Net income (loss)	54,597	130,687
Less preferred stock dividends	-5,203	-5,203
Net income (loss) available to common stockholders	$49,394	$125,484
Net income (loss) per common share basic & diluted	$0.31	$0.78
Dividends declared per common share	$0.30	$0.32

Consolidated_Statement_Of_Chan

Consolidated Statement Of Changes In Stockholders Equity (USD $)	Total		Common Stock Par Value	Additional Paid-in Capital	Accumulated Deficit	Series A Preferred Stock	Series B Preferred Stock
In Thousands
Balance at Dec. 31, 2014	$1,975,168	[1]	$1,618	$2,049,152	($341,502)	$72,369	$193,531
Net income (loss)	54,597		0	0	54,597	0	0
Issuance of common stock	0		4	-4	0	0	0
Amortization of share based compensation	954		0	954	0	0	0
Repurchase and cancellation of common stock	37,446		41	37,405	0	0	0
Preferred dividends	-5,203		0	0	-5,203	0	0
Common dividends	-47,434		0	0	-47,434	0	0
Balance at Mar. 31, 2015	$1,940,636		$1,581	$2,012,697	($339,542)	$72,369	$193,531
[1]	Derived from audited financial statements.

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	$54,597		$130,687
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Amortization of share based compensation	954		1,115
Amortization of premiums and discounts on investment securities	21,450		10,303
Amortization of premiums on interest rate cap contracts	4,375		6,254
Net realized (gain) loss on investments	-18,253		-16,670
Net unrealized (gain) loss on investments	-75,689		-89,234
Net unrealized (gain) loss on swap and cap contracts	74,800		16,240
Change in assets and liabilities:
Interest receivable	580		2,747
Other assets	-10,325		274
Accrued interest payable	4,214		-9,631
Accrued expenses and other liabilities	-2,814		-2,602
Net cash provided by (used in) operating activities	53,889		49,483
Cash flows from investing activities:
Purchase of investment securities	-6,863,933		-7,421,216
Proceeds from disposition of investment securities	6,018,216		7,788,084
Proceeds from paydowns of investment securities	462,438		279,846
Change in assets and liabilities:
Receivable for securities sold and principal repayments	-261,363		425,651
Payable for securities purchased	1,261,561		84,777
Increase (Decrease) in Cash Collateral for Borrowed Securities	-26,112		0
Payable for cash received as collateral	-24,542		18
Net cash provided by (used in) investing activities	566,265		1,157,160
Cash flows from financing activities:
Proceeds from repurchase agreements	23,743,739		21,193,497
Repayments of repurchase agreements	-24,828,397		-22,386,399
Proceeds from FHLB advances	1,010,000		0
Repayments of FHLB advances	-500,000		0
Net payments from repurchase of common stock	-37,446		-133
Distributions paid	-5,203		-5,204
Net cash used in financing activities	-617,307		-1,198,239
Net increase (decrease) in cash	2,847		8,404
Cash - Beginning of period	4,323	[1]	4,992
Cash - End of period	7,170		13,396
Supplemental disclosures of cash flow information:
Interest paid	28,522		41,220
Supplemental disclosures of non-cash flow information:
Distributions declared, not yet paid	$51,844		$56,258
[1]	Derived from audited financial statements.

Orginazation

Orginazation	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	ORGANIZATION
	CYS Investments, Inc. (the "Company" "we", "us", and "our,") was formed as a Maryland corporation on January 3, 2006, and commenced operations on February 10, 2006. The Company has elected to be taxed and intends to continue to qualify as a real estate investment trust ("REIT") and is required to comply with the provisions of the Internal Revenue Code of 1986, as amended (the "Code"), with respect thereto. The Company has primarily purchased residential mortgage-backed securities that are issued and the principal and interest of which are guaranteed by a federally chartered corporation ("Agency RMBS"), such as the Federal National Mortgage Association ("Fannie Mae") or the Federal Home Loan Mortgage Corporation ("Freddie Mac"), or an agency of the U.S. government such as the Government National Mortgage Association ("Ginnie Mae"), and debt securities issued by the United States Department of Treasury ("U.S. Treasuries"). The Company may also purchase collateralized mortgage obligations issued by a government agency or government-sponsored entity that are collateralized by Agency RMBS ("CMOs"), or securities issued by a government sponsored entity that are not backed by collateral but, in the case of government agencies, are backed by the full faith and credit of the U.S. government, and, in the case of government sponsored entities, are backed by the integrity and creditworthiness of the issuer ("U.S. Agency Debentures").
	The Company’s common stock, Series A Cumulative Redeemable Preferred Stock, $25.00 liquidation preference (the "Series A Preferred Stock"), and Series B Cumulative Redeemable Preferred Stock, $25.00 liquidation preference (the "Series B Preferred Stock"), trade on the New York Stock Exchange under the symbols "CYS," "CYS PrA" and "CYS PrB," respectively.
	In March 2015, our wholly-owned captive insurance subsidiary, CYS Insurance Services, LLC ("CYS Insurance"), was granted membership in the Federal Home Loan Bank ("FHLB") of Cincinnati. The 12 regional FHLBs provide long-term and short-term secured loans, called “advances,” to their members. FHLB members may use a variety of real estate related assets, including residential mortgage loans and Agency RMBS, as collateral for advances. Membership in the FHLB permits CYS Insurance to access a variety of products and services offered by the FHLB and obligates CYS Insurance to purchase membership stock and activity stock, the latter being a percentage of the advances it obtains from the FHLB. We intend for CYS Insurance to seek advances of both short- and long-term indebtedness from the FHLB of Cincinnati.

Significant_Accounting_Policie

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES
	Basis of Presentation
	The accompanying interim consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the instructions to Securities and Exchange Commission ("SEC") Form 10-Q and Article 10, Rule 10-01 of Regulation S-X. Accordingly, the financial statements do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The interim consolidated financial statements should be read in conjunction with the Company’s audited financial statements as of and for the year ended December 31, 2014, included in its 2014 Annual Report. The results for interim periods are not necessarily indicative of the results to be expected for the fiscal year.
	The interim consolidated financial statements include the accounts of the Company and all of its subsidiaries. All intercompany balances and transactions have been eliminated. The interim consolidated financial statements of the Company have been prepared on the accrual basis of accounting in accordance with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make a number of estimates and assumptions that affect the amounts reported in the interim consolidated financial statements and accompanying footnotes. Actual results could differ from these estimates and the differences may be material.
	Investments in Securities
	The Company's investment securities are accounted for in accordance with Accounting Standards Codification ("ASC") 320—Investments in Debt and Equity Securities. The Company has chosen to make a fair value election pursuant to ASC 825—Financial Instruments for its securities and, therefore, our investment securities are recorded at fair market value on the consolidated balance sheets. The periodic changes in fair market value are recorded in current period earnings on the consolidated statements of operations as a component of net unrealized gain (loss) on investments. These investments generally meet the requirements to be classified as available-for-sale under ASC 320, which requires the securities to be carried at fair value on the balance sheet. Electing the fair value option permits the Company to record changes in fair value of our investments in the consolidated statements of operations, which in management’s view, more appropriately reflects the results of operations for a particular reporting period as all securities activities will be recorded in a similar manner.
	The Company records its transactions in securities on a trade date basis. We record realized gains and losses on securities transactions on an identified cost basis.
	The Company accounts for its investment in FHLB stock as a cost method investment in "Other Assets".
	Agency RMBS
	The Company’s investments in Agency RMBS consist of pass-through certificates backed by fixed-rate, monthly-reset adjustable-rate loans (“ARMs”) and hybrid ARMs, the principal and interest of which are guaranteed by Fannie Mae, Freddie Mac or Ginnie Mae. Hybrid ARMs have interest rates that have an initial fixed period (typically three, five, seven or ten years) and thereafter reset at regular intervals in a manner similar to ARMs.
	Forward Settling Transactions
	The Company engages in forward settling transactions to purchase certain securities. The Company records forward settling transactions on the trade date, and maintains security positions such that sufficient liquid assets will be available to make payment on the settlement date for the securities purchased. The Agency RMBS purchased at the forward settlement date are typically priced at a discount to securities for settlement in the current month. Securities purchased on a forward settling basis are carried at fair value and begin earning interest on the settlement date. Gains or losses may occur on these transactions due to changes in market conditions or the failure of counterparties to perform under the contract. Along with other forward settling transactions, the Company transacts in to-be-announced (“TBA”) securities. As with other forward settling transactions, a seller agrees to issue TBAs at a future date; however, the seller does not specify the particular securities to be delivered. Instead, the Company agrees to accept any security that meets specified terms such as issuer, interest rate and terms of underlying mortgages. The Company records TBAs on the trade date utilizing information associated with the specified terms of the transaction as opposed to the specific mortgages. TBAs are carried at fair value and begin earning interest on the settlement date. Gains or losses may occur due to the fact that the actual underlying mortgages received may be more or less favorable than those anticipated by the Company. See Note 7, Pledged Assets, for disclosure regarding the fair value of collateral pledged or received on forward settling transactions.
	At times, the Company may enter into TBA contracts as a means of investing in and financing Agency RMBS via “dollar roll” transactions.  TBA dollar roll transactions involve moving the settlement of a TBA contract out to a later date by entering into an offsetting short position (referred to as a “pair off”), net settling the paired off positions for cash, and simultaneously purchasing a similar TBA contract for a later settlement date.  The Company records such pair offs on a gross basis such that there is a sale of the original TBA and a subsequent purchase of a new TBA.
	Investment Valuation
	The Company has a pricing committee responsible for establishing valuation policies and procedures, as well as reviewing and approving valuations at a monthly pricing meeting. The pricing committee is composed of individuals from the accounting team, the investment team and senior management.
	Agency RMBS, Agency Debentures and U.S. Treasuries are generally valued based on prices provided by third-party services, as derived from such services’ pricing models. Inputs to the models may include, but are not limited to, reported trades, executable bid and ask prices, broker quotations, prices or yields of securities with similar characteristics, benchmark curves or information pertaining to the issuer, as well as industry and economic events. The pricing services may also use a matrix approach, which considers information regarding securities with similar characteristics to determine the valuation for a security.
	We generally value interest rate swaps and caps using prices provided by broker quotations. Such broker quotations are based on the present value of fixed and projected floating rate cash flows over the term of the swap contract. Future cash flows are discounted to their present value using swap rates provided by electronic data services or by brokers. No credit valuation adjustments were made in determining the fair value of the Company's interest rate swaps and caps.
	Fair values of long-lived assets, including real estate, are primarily derived internally, and are based on inputs observed from sales transactions of similar assets. For real estate, fair values are also based on comparable contemporaneous sales transactions and/or discounted cash flow estimates which reflect current and projected lease profiles and available industry information about capitalization rates and expected trends in rents and occupancy.
	All valuations from third-party pricing services or broker quotes are non-binding. We review all prices during our pricing process. To date, the Company has not adjusted any of the prices received from third-party pricing services or brokers. Our pricing review includes comparisons of similar market transactions, alternative third-party pricing services and broker quotes, or comparisons to a pricing model. To ensure the proper fair value hierarchy, the Company reviews the third-party pricing services methodology periodically to understand whether observable or unobservable inputs are being used. See Note 8, Fair Value Measurements, for a discussion of how the Company values its assets.
	Interest Income
	We record interest income and expense on an accrual basis. We accrue interest income based on the outstanding principal amount of the securities and their contractual terms. We amortize premium and discount using the effective interest method, and this net amortization is either accretive to or a reduction of interest income from Agency RMBS in the Company's consolidated statements of operations. The Company does not estimate prepayments when calculating the yield to maturity on Agency RMBS. We record the amount of premium or discount associated with a prepayment through interest income from Agency RMBS on our consolidated statements of operations as it occurs.
	Other Assets -- Investment in FHLB Stock
	The Company's subsidiary, CYS Insurance, is a member of, and owns capital stock in, the FHLB of Cincinnati. The FHLB provides CYS Insurance with credit capacity and authorizes advances based on the security of pledged Agency RMBS, provided the Company meets certain creditworthiness standards. FHLB advances, included in the "FHLB advances" line item, is a funding source for the Company of both short- and long-term indebtedness. As a condition of its membership in the FHLB, CYS Insurance is required to maintain a FHLB stock investment, both for membership and for the level of advances from the FHLB to the Company. The Company accounts for its investment in FHLB stock as a cost method investment in "Other Assets".
	Repurchase Agreements and FHLB Advances
	Borrowings under repurchase agreements ("repo borrowings") and FHLB advances are collateralized by the Company’s Agency RMBS and U.S. Treasuries (collectively, "Debt Securities") and carried at their amortized cost, which approximates their fair value due to their short-term nature (generally 30-90 days). The Company’s repurchase agreement counterparties are institutional dealers in fixed income securities and large financial institutions, and in the case of FHLB advances, the FHLB of Cincinnati. Collateral under repurchase agreements and FHLB advances are valued daily and counterparties may require additional collateral when the fair value of the collateral declines. Counterparties have the right to sell or repledge collateral pledged under repurchase agreements and the FHLB advances agreement. See Note 5, Repurchase Agreements.
	We account for our repo borrowings and FHLB advances as short-term indebtedness under ASC 470—Debt; accordingly, these short-term instruments are accounted for in our financial statements at carrying value, or historic cost.
	Interest Rate Swap and Cap Contracts
	We account for our interest rate swap and cap contracts transactions under ASC 815—Derivatives and Hedging. The Company uses interest rate swaps and interest rate caps to hedge a portion of its exposure to market risks, including interest rate risk, credit risk and extension risk. The objective of our risk management strategy is to reduce fluctuations in stockholders’ equity over a range of interest rate scenarios. In particular, we attempt to manage the risk of the cost of our variable rate liabilities increasing during a period of rising interest rates.
	During the term of an interest rate swap or cap, the Company makes or receives periodic payments and records unrealized gains or losses as a result of marking the swap or cap to their fair value. When the Company terminates a swap or cap, we record a realized gain or loss equal to the difference between the proceeds from (or cost of) the closing transaction and the Company's cost basis in the contract, if any. We report the periodic payments and amortization of premiums on cap contracts under interest expense in the consolidated statements of operations. Swaps involve a risk that interest rates will move contrary to the Company’s expectations, thereby increasing the Company’s payment obligation.
	The Company's interest rate swap and cap contracts may be subject to a master netting arrangement ("MNA"). The Company is exposed to credit loss in the event of non-performance by the counterparty to the swap or cap limited to the fair value of collateral posted in excess of the fair value of the contract in a net liability position and the shortage of the fair value of collateral posted for the contract in a net asset position. As of March 31, 2015 and December 31, 2014, the Company did not anticipate non-performance by any counterparty. Should interest rates move unexpectedly, the Company may not achieve the anticipated benefits of the interest rate swap or cap and may realize a loss.
	While the Company's derivative agreements generally permit for netting or setting off derivative assets and liabilities with the counterparty, the Company reports related assets and liabilities on a gross basis in our consolidated balance sheets. Derivative instruments in a gain position are reported as derivative assets at fair value and derivative instruments in a loss position are reported as derivative liabilities at fair value in our consolidated balance sheets. We record changes in fair value of our derivative instruments in net unrealized gain (loss) on swap and cap contracts in our consolidated statements of operations. Cash receipts and payments related to derivative instruments are classified in our consolidated statements of cash flows in accordance with U.S. GAAP in both the operating and investing activities sections in the Company’s consolidated statement of cash flows. See Note 4, Investments in Interest Rate Swap and Cap Contracts.

Investments_in_Securities

Investments in Securities	3 Months Ended
	Mar. 31, 2015
Available-for-sale Securities [Abstract]
Investments in Securities and Other Assets	INVESTMENT IN SECURITIES
	The available-for-sale portfolio consisted of the following as of March 31, 2015 and December 31, 2014 (in thousands):
	March 31, 2015
	Asset Type		Amortized Cost				Gross Unrealized Loss			Gross Unrealized Gain		Fair Value
	Fannie Mae Certificates
	Fixed Rate		$	12,326,027			$	(281	)	$	201,906	$	12,527,652
	ARMs		597,368				(1		)	8,959		606,326
	Total Fannie Mae		12,923,395				(282		)	210,865		13,133,978
	Freddie Mac Certificates
	Fixed Rate		1,211,409				(98		)	26,432		1,237,743
	ARMs		119,673				(221		)	1,808		121,260
	Total Freddie Mac		1,331,082				(319		)	28,240		1,359,003
	Ginnie Mae Certificates - ARMs		61,298				—			1,665		62,963
	U.S. Treasuries		497,553				—			3,781		501,334
	Other Investments		6,945				—			1,080		8,025
	Total		$	14,820,273			$	(601	)	$	245,631	$	15,065,303
	December 31, 2014
	Fannie Mae Certificates
	Fixed Rate		$	11,356,716			$	(2,984	)	$	158,571	$	11,512,303
	ARMs		1,282,065				(13,144		)	4,449		1,273,370
	Total Fannie Mae		12,638,781				(16,128		)	163,020		12,785,673
	Freddie Mac Certificates
	Fixed Rate		1,183,764				—			25,769		1,209,533
	ARMs		394,726				(6,753		)	1,144		389,117
	Total Freddie Mac		1,578,490				(6,753		)	26,913		1,598,650
	Ginnie Mae Certificates - ARMs		66,390				—			1,743		68,133
	U.S. Treasuries		149,585				(534		)	—		149,051
	Other Investments		6,945				—			1,080		8,025
	Total		$	14,440,191			$	(23,415	)	$	192,756	$	14,609,532
	The following table presents the gross unrealized loss and fair values of our available-for-sale Agency RMBS by length of time that such securities have been in a continuous unrealized loss position as of March 31, 2015 and December 31, 2014 (in thousands):
			Unrealized loss positions for
			Less than 12 Months							Greater than 12 months					Total
	As of		Fair value				Unrealized loss			Fair value		Unrealized loss			Fair value		Unrealized loss
	March 31, 2015		$	258,991			$	(380	)	$	97,643	$	(221	)	$	356,634	$	(601	)
	December 31, 2014		259,291				(577		)	1,494,884		(22,838		)	1,754,175		(23,415		)
	The following table is a summary of our net realized gain (loss) from the sale of available-for-sale investments for the three months ended March 31, 2015 and 2014 (in thousands):
		Three Months Ended March 31,
		2015				2014
	Available-for-sale investments, at cost	$	5,999,963			$	7,771,414
	Proceeds from available-for-sale investments sold	6,018,216				7,788,084
	Net gain on sale of available-for-sale investments	$	18,253			$	16,670
	Gross gain on sale of available-for-sale investments	$	33,979			$	51,142
	Gross loss on sale of available-for-sale investments	(15,726		)		(34,472		)
	Net gain on sale of available-for-sale investments	$	18,253			$	16,670
	The components of the carrying value of available-for-sale securities at March 31, 2015 and December 31, 2014 are presented below. The premium purchase price is due to the average coupon interest rates on these investments being higher than prevailing market rates, and conversely, the discount purchase price is due to the average coupon interest rates on these investments being lower than prevailing market rates.
	(in thousands)		March 31, 2015				December 31, 2014
	Principal balance		$	14,244,501			$	13,887,897
	Unamortized premium		578,370				552,869
	Unamortized discount		(2,598		)		(575		)
	Gross unrealized gains		245,631				192,756
	Gross unrealized losses		(601		)		(23,415		)
	Fair value		$	15,065,303			$	14,609,532
	Our weighted-average coupon interest rate on the Company's Debt Securities as of March 31, 2015 and December 31, 2014 was 3.38% and 3.39%, respectively. Actual maturities of Agency RMBS are generally shorter than stated contractual maturities (which range up to 30 years), as they are affected by the contractual lives of the underlying mortgages, periodic payments and prepayments of principal.
	As of March 31, 2015, the range of final contractual maturity of the Company’s Agency RMBS portfolio was between 2024 and 2045 and the final maturity of the Company's U.S. Treasuries was between 2018 and 2020. As of December 31, 2014, the range of final contractual maturity of the Company’s Agency RMBS portfolio was between 2024 and 2045 the final maturity of the Company's U.S. Treasuries was 2019.
	Credit Risk
	The Company believes it has minimal exposure to credit losses on its investment securities assets at March 31, 2015 and December 31, 2014 because it owns principally Debt Securities. Principal and interest payments on Agency RMBS are guaranteed by Freddie Mac and Fannie Mae, while principal and interest payments on Ginnie Mae RMBS and U.S. Treasuries are backed by the full faith and credit of the U.S. government. In September 2008, both Freddie Mac and Fannie Mae were placed in the conservatorship of the U.S. government. On August 5, 2011, Standard & Poor’s ("S&P") downgraded the U.S. government’s credit rating for the first time to AA+. Fitch Ratings Inc. ("Fitch") announced on October 15, 2013 that it had placed the U.S. government's credit rating on "negative watch". This negative watch was changed to "stable" on March 21, 2014.
	As of March 31, 2015, S&P has maintained its AA+ rating, while Fitch and Moody's rated the U.S. government AAA and Aaa, respectively. Because Fannie Mae and Freddie Mac are still in U.S. government conservatorship, the implied credit ratings of Agency RMBS were similarly rated. While the conservatorship, ratings downgrade and ratings watch appear not to have had a significant impact on the fair value of the Agency RMBS or U.S. Treasuries in the Company’s portfolio, these developments increased the uncertainty regarding the credit risk of Debt Securities.

Investments_in_Interest_Rate_S

Investments in Interest Rate Swap and Cap Contracts	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Fair Value [Text Block]	INVESTMENTS IN INTEREST RATE SWAP AND CAP CONTRACTS
	With the intent of managing our interest rate exposure, the Company enters into interest rate swap and cap contracts. The Company had the following activity in interest rate swap and cap transactions during the three months ended March 31, 2015 and 2014 (in thousands):
	Three Months Ended March 31, 2015							Three Months Ended March 31, 2014
	Trade Date	Transaction		Notional				Trade Date		Transaction	Notional
	Jan-15	Terminated		$	(400,000	)		Feb-14		Terminated	$	(500,000	)
	Jan-15	Opened		500,000				Net Decrease			$	(500,000	)
	Net Increase			$	100,000
	As of March 31, 2015 and December 31, 2014, the Company had pledged Debt Securities with a fair value of $80.5 million and $60.9 million, respectively, as collateral on interest rate swap and cap contracts. As of March 31, 2015, the Company had Debt Securities of $34.6 million and cash of $47.7 million pledged to it as collateral for its interest rate swap and cap contracts. As of December 31, 2014, the Company had Debt Securities of $47.2 million and cash of $72.0 million pledged to it as collateral for its interest rate cap contracts. See Note 7, Pledged Assets. Below is a summary of our interest rate swap and cap contracts open as of March 31, 2015 and December 31, 2014 (in thousands):
	Derivatives not designated as hedging instruments under ASC 815
	Interest Rate Swap Contracts	Notional				Fair Value				Consolidated Balance Sheets
	March 31, 2015	$	4,000,000			$	(38,502	)		Derivative liabilities, at fair value
	March 31, 2015	3,750,000				11,333				Derivative assets, at fair value
	December 31, 2014	2,600,000				(16,007		)		Derivative liabilities, at fair value
	December 31, 2014	5,050,000				40,611				Derivative assets, at fair value
	Interest Rate Cap Contracts	Notional				Fair Value				Consolidated Balance Sheets
	March 31, 2015	$	2,500,000			$	80,271			Derivative assets, at fair value
	December 31, 2014	2,500,000				107,673				Derivative assets, at fair value
	The following table presents information about the net realized and unrealized gain and loss on swap and cap contracts for the three months ended March 31, 2015 and 2014 on the Company's interest rate swap and cap contracts not designated as hedging instruments under ASC 815 (in thousands):
				Amount Recognized in Income on Derivatives
				Three Months Ended March 31,
	Derivative Type	Location of Gain or (Loss) Recognized in Income on Derivative		2015				2014
	Interest rate swaps and caps	Net realized gain (loss) on termination of swap and cap contracts		$	(2,568	)		$	(9,323	)
	Interest rate swaps and caps	Net unrealized gain (loss) on swap and cap contracts		(74,800		)		(16,240		)
	Interest rate swaps and caps	Total recognized in income on derivatives		$	(77,368	)		$	(25,563	)
	We continue to reposition our hedges, and in January 2015 entered into a 7-year $500 million notional swap at a pay rate of 2.15%, cancelable in January 2016, and at the same time we terminated a 7-year $400 million notional interest rate swap at a pay rate of 2.416%, cancelable in June 2015.

Repurchase_Agreements_and_FHLB

Repurchase Agreements and FHLB Advances	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Repurchase Agreements	REPURCHASE AGREEMENTS AND FHLB ADVANCES
	The Company leverages its portfolio through repo borrowings and FHLB advances. Each of the Company's repo borrowings bear interest at a floating rate based on a spread above or below London Interbank Offered Rate ("LIBOR"). The interest rates for FHLB advances are set by the FHLB of Cincinnati. The fair value of repo borrowings and FHLB advances approximates their carrying amount due to the short-term nature of these financial instruments.
	Certain information with respect to the Company’s repo borrowings and FHLB advances outstanding at the balance sheet date is summarized in the table below. Each of the repo borrowings and the FHLB advances are contractually due in one year or less.
	(in thousands)	March 31, 2015			December 31, 2014
	Outstanding repurchase agreements	$	10,204,901		$	11,289,559
	Outstanding FHLB advances	$	510,000		$	—
	Interest accrued thereon	$	3,574		$	5,334
	Weighted-average borrowing rate(1)	0.34		%	0.35		%
	Weighted-average remaining maturity (in days)	43.6			28.2
	Fair value of the collateral(2)	$	11,212,170		$	11,842,427
	__________________
	-1	The weighted-average borrowing rate as of March 31, 2015 was determined as set forth in the table below.
	Collateral	Borrowing amount			Rate
	Agency RMBS	$	10,243,805		0.36	%
	U.S. Treasuries	471,096			(0.04	)%
	Total / weighted-average borrowing rate	$	10,714,901		0.34	%
	-2	Collateral for repo borrowings and FHLB advances consisted of Agency RMBS and U.S. Treasuries.
	At March 31, 2015 and December 31, 2014, the Company had no repo borrowings or FHLB advances where the amount at risk with an individual counterparty exceeded 1.6% and 1.6% of stockholders' equity, respectively. In addition, we had no repo borrowings or FHLB advances with any counterparty that exceeded 4% of our total assets.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES
	The Company enters into certain agreements that contain a variety of indemnifications, principally with broker dealers. As of March 31, 2015 and December 31, 2014, no claims have been asserted under these indemnification agreements. Accordingly, the Company has no liabilities recorded for these agreements as of March 31, 2015 and December 31, 2014.

Pledged_Assets

Pledged Assets	3 Months Ended
	Mar. 31, 2015
Transfers and Servicing [Abstract]
Pledged Assets	PLEDGED ASSETS
	Assets Pledged to Counterparties
	The following tables summarize our assets pledged as collateral under our repo borrowings, FHLB advances, and derivative agreements by type, including securities pledged related to securities purchased or sold but not yet settled, as of March 31, 2015 and December 31, 2014 (in thousands):
	March 31, 2015
	Assets Pledged to Counterparties		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	10,752,304			$	56,339			$	991			$	10,809,634
	U.S. Treasuries - fair value		476,142				24,204				—				500,346
	Accrued interest on pledged securities		29,790				245				2				30,037
	Cash		—				37,216				—				37,216
	Total		$	11,258,236			$	118,004			$	993			$	11,377,233
	December 31, 2014
	Assets Pledged to Counterparties		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	11,697,532			$	42,894			$	1,453			$	11,741,879
	U.S. Treasuries - fair value		149,051				17,992				—				167,043
	Accrued interest on pledged securities		31,475				168				3				31,646
	Cash		—				11,104				—				11,104
	Total		$	11,878,058			$	72,158			$	1,456			$	11,951,672
	Assets Pledged from Counterparties
	As the estimated fair value of our investment securities pledged as collateral increases due to changes in interest rates or other factors, we may require counterparties to release collateral back to us, which may be in the form of identical securities, similar securities, or cash. As of March 31, 2015 and December 31, 2014, we also had assets pledged to us as collateral under our repurchase and derivative agreements summarized in the tables below (in thousands):
	March 31, 2015
	Assets Pledged to CYS		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	5,154			$	15,787			$	646			$	21,587
	U.S. Treasuries - fair value		11,122				18,805				—				29,927
	Accrued interest on pledged securities		82				85				2				169
	Cash		—				47,670				559				48,229
	Total		$	16,358			$	82,347			$	1,207			$	99,912
	December 31, 2014
	Assets Pledged to CYS		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	3,464			$	22,112			$	3,225			$	28,801
	U.S. Treasuries - fair value		692				25,115				—				25,807
	Accrued interest on pledged securities		13				142				9				164
	Cash		—				71,980				791				72,771
	Total		$	4,169			$	119,349			$	4,025			$	127,543
	Cash collateral received is recognized in "Cash" with a corresponding amount recognized in "Payable for cash received as collateral" on the accompanying interim consolidated balance sheets. Securities collateral received from counterparties is disclosed as a component of our liquidity amount in Note 4, Investment in Interest Rate Swap and Cap Contracts.
	Cash and Debt Securities we pledge as collateral under our derivatives agreements are included in "Cash" and "Investment in securities, at fair value" on our consolidated balance sheets.
	Offsetting Assets and Liabilities
	Certain of our repurchase agreements and derivative transactions are governed by underlying agreements that generally provide for a right of set-off 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. Under U.S. GAAP, if the Company has a valid right of set-off, it may offset the related asset and liability and report the net amount. However, the Company reports amounts subject to its Master Repurchase Agreements (“MRA”s) and International Standard Derivative Association ("ISDA") Agreements in the consolidated balance sheets on a gross basis without regard to such rights of offset.
	At March 31, 2015 and December 31, 2014, the Company's derivative assets and liabilities (by type) are as follows (in thousands):
	March 31, 2015		Assets				Liabilities
	Interest rate swap contracts		$	11,333			$	38,502
	Interest rate cap contracts		80,271				—
	Total derivative assets and liabilities in the interim consolidated balance sheet		91,604				38,502
	Derivatives not subject to an MNA		843				30,684
	Total assets and liabilities subject to an MNA		$	90,761			$	7,818
	December 31, 2014		Assets				Liabilities
	Interest rate swap contracts		$	40,611			$	16,007
	Interest rate cap contracts		107,673				—
	Total derivative assets and liabilities in the interim consolidated balance sheet		148,284				16,007
	Derivatives not subject to an MNA		7,008				11,579
	Total assets and liabilities subject to an MNA		$	141,276			$	4,428
	Below is a summary of the Company's assets subject to offsetting provisions (in thousands):
									Gross Amounts Not Offset in the Consolidated Balance Sheet
	As of		Description		Amounts of Assets Presented in the Consolidated Balance Sheet				Instruments Available for Offset				Collateral Received(1)				Net Amount(2)
	March 31, 2015		Derivative assets		$	90,761			$	2,546			$	79,995			$	8,220
	December 31, 2014		Derivative assets		141,276				4,341				117,991				18,944
	_________________
	-1	Collateral consists of Agency RMBS, U.S. Treasuries and cash. Excess collateral received is not shown for financial reporting purposes.
	-2	Net amount represents the net amount receivable from the counterparty in the event of default.
	Below is a summary of the Company's liabilities subject to offsetting provisions (in thousands):
									Gross Amounts Not Offset in the Consolidated Balance Sheet
	As of		Description		Amounts of Liabilities Presented in the Consolidated Balance Sheet				Instruments Available for Offset				Collateral Pledged(1)				Net Amount(2)
	March 31, 2015		Derivative liabilities		$	7,818			$	2,546			$	5,272			$	—
	March 31, 2015		Repurchase agreements		10,204,901				—				10,204,901				—
	31-Dec-14		Derivative liabilities		$	4,428			$	4,341			$	87			$	—
31-Dec-14		Repurchase agreements		11,289,559				—				11,289,559				—
_______________
-1	Collateral consists of Agency RMBS, U.S. Treasuries and Cash. Excess collateral pledged is not shown for financial reporting purposes.
-2	Net amount represents the net amount payable to the counterparty in the event of default.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS
	The Company’s valuation techniques are based on observable and unobservable inputs. Observable inputs reflect readily obtainable data from independent sources, while unobservable inputs reflect the Company’s market assumptions. ASC 820—Fair Value Measurements. The following tables provide a summary of the Company’s assets and liabilities that are measured at fair value, and recorded and presented at fair value as of March 31, 2015 and December 31, 2014 (in thousands):
	March 31, 2015	Fair Value Measurements Using
		Level 1		Level 2		Level 3		Total
	Assets
	Agency RMBS	$	—	$	14,555,943	$	—	$	14,555,943
	U.S. Treasuries	501,335		—		—		501,335
	Other Investments					8,025		8,025
	Derivative assets	—		91,604		—		91,604
	Total	$	501,335	$	14,647,547	$	8,025	$	15,156,907
	Liabilities
	Derivative liabilities	$	—	$	38,502	$	—	$	38,502
	December 31, 2014	Fair Value Measurements Using
		Level 1		Level 2		Level 3		Total
	Assets
	Agency RMBS	$	—	$	14,452,456	$	—	$	14,452,456
	U.S. Treasuries	149,051		—		—		149,051
	Other investments	—		—		8,025		8,025
	Derivative assets	—		148,284		—		148,284
	Total	$	149,051	$	14,600,740	$	8,025	$	14,757,816
	Liabilities
	Derivative liabilities	$	—	$	16,007	$	—	$	16,007
	Other Investments is comprised of our investment in a real estate asset, which is a Level 3 asset. The table below presents a reconciliation of changes in other investments classified as Level 3 in the Company’s interim consolidated financial statements for the three months ended March 31, 2015 and 2014.
	Fair values of real estate assets are valued based on comparable sales transactions and/or on discounted cash flow models. A discussion of the method of fair valuing these assets is included in Note 2, Significant Accounting Policies—Investments in Securities—Investment Valuation. The significant unobservable input used in the fair value measurement is capitalization rates, which the Company estimated to be between 3% and 6% at March 31, 2015 and December 31, 2014.
	We account for our repo borrowings and FHLB advances under ASC ASC 470—Debt; accordingly, these short-term instruments are disclosed at carrying value, or historic cost.
	Level 3 Fair Value Reconciliation
	(In thousands)	Three Months Ended March 31,
	Other investments	2015		2014
	Beginning balance Level 3 assets	$	8,025	$	6,945
	Cash payments recorded as a reduction of cost basis	—		—
	Change in net unrealized gain (loss)	—		—
	Gross purchases	—		—
	Gross sales	—		—
	Net gain (loss) on sales	—		—
	Transfers into (out of) Level 3	—		—
	Ending balance Level 3 assets	$	8,025	$	6,945

Share_Capital

Share Capital	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Share Capital	SHARE CAPITAL
	The Company has authorized 500,000,000 shares of common stock having par value of $0.01 per share. As of March 31, 2015 and December 31, 2014, the Company had issued and outstanding 158,114,483 and 161,849,878 shares of common stock, respectively.
	The Company has authorized 50,000,000 shares of preferred stock having a par value of $0.01 per share. As of March 31, 2015 and December 31, 2014, 3,000,000 shares of 7.75% Series A Preferred Stock ($25.00 liquidation preference) were issued and outstanding. As of March 31, 2015 and December 31, 2014, 8,000,000 shares of 7.50% Series B Preferred Stock ($25.00 liquidation preference) were issued and outstanding. The Series A Preferred Stock and Series B Preferred Stock will not be redeemable before August 3, 2017 and April 30, 2018, respectively, except under circumstances where it is necessary to preserve the Company's qualification as a REIT, for federal income tax purposes, or the occurrence of a change of control. On or after August 3, 2017 and April 30, 2018, the Company may, at its option, redeem any or all of the shares of the Series A Preferred Stock and Series B Preferred Stock, respectively, at $25.00 per share plus any accumulated and unpaid dividends to, but not including, the respective redemption date. The Series A Preferred Stock and Series B Preferred Stock have no stated maturity, and are not subject to any sinking fund requirement or mandatory redemption.
	Equity Offerings
	On May 23, 2014, the Company filed an automatically effective shelf registration statement on Form S-3 with the SEC. The Company may offer and sell, from time to time, shares of common stock, preferred stock and debt securities in one or more offerings pursuant to the prospectus that is a part of the registration statement. As of March 31, 2015, the Company had not issued any shares of common stock, preferred stock or debt securities under the prospectus.
	Equity Placement Program (“EPP”)
	Effective May 15, 2014, the Company terminated that certain Equity Distribution Agreement by and between the Company and JMP Securities LLC (“JMP”), dated as of June 7, 2011 (the “JMP Agreement”), in connection with the expiration of the Company’s prior shelf registration statement on Form S-3. Under the JMP Agreement, the Company could offer and sell, from time to time, up to 15.0 million shares of the Company’s common stock through an “at the market” offering program with JMP. For the three months ended March 31, 2015 and 2014, the Company did not sell any shares of common stock under the JMP Agreement.
	Dividend Reinvestment and Direct Stock Purchase Plan (“DSPP”)
	The Company sponsors a dividend reinvestment and direct stock purchase plan through which stockholders may purchase additional shares of common stock by reinvesting some or all cash dividends received on shares of common stock. Stockholders may also make optional cash purchases of shares of common stock subject to certain limitations detailed in the plan prospectus. For the three months ended March 31, 2015 and 2014 the Company did not issue any shares under the plan. As of March 31, 2015 and December 31, 2014, there were approximately 4.1 million shares available for issuance under the plan.
	Share Repurchase Program
	On November 15, 2012, the Company announced that its Board of Directors authorized the repurchase of shares of the Company’s common stock having an aggregate value of up to $250 million. Pursuant to this program, through July 20, 2014, the Company repurchased approximately $115.7 million in aggregate value of its shares of common stock on the open market. On July 21, 2014, the Company announced that its Board of Directors authorized the repurchase of shares of the Company's common stock having an aggregate value of up to $250 million, which included the approximately $134.3 million available for repurchase under the November 2012 authorization. Subsequently in 2014, we repurchased 172,549 shares for an aggregate of approximately $1.5 million. In the first quarter of 2015, we repurchased 4,149,571 shares at a weighted-average purchase price of $8.95, for an aggregate of approximately $37.2 million. Accordingly, the Company still had approximately $211.2 million authorized to repurchase shares of its common stock as of March 31, 2015.
	Restricted Stock Awards
	For the three months ended March 31, 2015 and 2014, the Company granted 438,617 and 389,880 shares of restricted stock, respectively, to certain of its directors, officers and employees.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE
	Components of the computation of basic and diluted earnings per share ("EPS") were as follows (in thousands except per share amounts):
		Three Months Ended March 31,
		2015			2014
	Net income (loss)	$	54,597		$	130,687
	Less preferred stock dividends	(5,203		)	(5,203		)
	Net income (loss) available to common stockholders	49,394			125,484
	Less dividends paid:
	Common shares	(47,110		)	(51,515		)
	Unvested shares	(324		)	(334		)
	Undistributed earnings (loss)	1,960			73,635
	Basic weighted-average shares outstanding:
	Common shares	159,573			160,936
	Basic earnings (loss) per common share:
	Distributed earnings	$	0.3		$	0.32
	Undistributed earnings (loss)	0.01			0.46
	Basic earnings (loss) per common share	$	0.31		$	0.78
	Diluted weighted-average shares outstanding:
	Common shares	159,573			160,936
	Net effect of dilutive stock options (1)	—			—
		159,573			160,936
	Diluted earnings (loss) per common share:
	Distributed earnings	$	0.3		$	0.32
	Undistributed earnings (loss)	0.01			0.46
	Diluted earnings (loss) per common share	$	0.31		$	0.78
	__________________
	-1	For the three months ended March 31, 2015 and 2014, the Company had an aggregate of 131,088 stock options outstanding with a weighted-average exercise price of $30.00 that were not included in the calculation of EPS, as their inclusion would have been anti-dilutive. These instruments may have a dilutive impact on future EPS.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS
	On April 1, 2015, an aggregate of 21,303 shares of restricted common stock were granted to certain directors as a portion of their compensation for serving on the Company’s Board of Directors.

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis Of Presentation	Basis of Presentation
	The accompanying interim consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the instructions to Securities and Exchange Commission ("SEC") Form 10-Q and Article 10, Rule 10-01 of Regulation S-X. Accordingly, the financial statements do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The interim consolidated financial statements should be read in conjunction with the Company’s audited financial statements as of and for the year ended December 31, 2014, included in its 2014 Annual Report. The results for interim periods are not necessarily indicative of the results to be expected for the fiscal year.
	The interim consolidated financial statements include the accounts of the Company and all of its subsidiaries. All intercompany balances and transactions have been eliminated. The interim consolidated financial statements of the Company have been prepared on the accrual basis of accounting in accordance with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make a number of estimates and assumptions that affect the amounts reported in the interim consolidated financial statements and accompanying footnotes. Actual results could differ from these estimates and the differences may be material.
Investments in Securities	Investments in Securities
	The Company's investment securities are accounted for in accordance with Accounting Standards Codification ("ASC") 320—Investments in Debt and Equity Securities. The Company has chosen to make a fair value election pursuant to ASC 825—Financial Instruments for its securities and, therefore, our investment securities are recorded at fair market value on the consolidated balance sheets. The periodic changes in fair market value are recorded in current period earnings on the consolidated statements of operations as a component of net unrealized gain (loss) on investments. These investments generally meet the requirements to be classified as available-for-sale under ASC 320, which requires the securities to be carried at fair value on the balance sheet. Electing the fair value option permits the Company to record changes in fair value of our investments in the consolidated statements of operations, which in management’s view, more appropriately reflects the results of operations for a particular reporting period as all securities activities will be recorded in a similar manner.
	The Company records its transactions in securities on a trade date basis. We record realized gains and losses on securities transactions on an identified cost basis.
Agency RMBS	Agency RMBS
	The Company’s investments in Agency RMBS consist of pass-through certificates backed by fixed-rate, monthly-reset adjustable-rate loans (“ARMs”) and hybrid ARMs, the principal and interest of which are guaranteed by Fannie Mae, Freddie Mac or Ginnie Mae. Hybrid ARMs have interest rates that have an initial fixed period (typically three, five, seven or ten years) and thereafter reset at regular intervals in a manner similar to ARMs.
Forward Settling Transactions	Forward Settling Transactions
	The Company engages in forward settling transactions to purchase certain securities. The Company records forward settling transactions on the trade date, and maintains security positions such that sufficient liquid assets will be available to make payment on the settlement date for the securities purchased. The Agency RMBS purchased at the forward settlement date are typically priced at a discount to securities for settlement in the current month. Securities purchased on a forward settling basis are carried at fair value and begin earning interest on the settlement date. Gains or losses may occur on these transactions due to changes in market conditions or the failure of counterparties to perform under the contract. Along with other forward settling transactions, the Company transacts in to-be-announced (“TBA”) securities. As with other forward settling transactions, a seller agrees to issue TBAs at a future date; however, the seller does not specify the particular securities to be delivered. Instead, the Company agrees to accept any security that meets specified terms such as issuer, interest rate and terms of underlying mortgages. The Company records TBAs on the trade date utilizing information associated with the specified terms of the transaction as opposed to the specific mortgages. TBAs are carried at fair value and begin earning interest on the settlement date. Gains or losses may occur due to the fact that the actual underlying mortgages received may be more or less favorable than those anticipated by the Company. See Note 7, Pledged Assets, for disclosure regarding the fair value of collateral pledged or received on forward settling transactions.
	At times, the Company may enter into TBA contracts as a means of investing in and financing Agency RMBS via “dollar roll” transactions.  TBA dollar roll transactions involve moving the settlement of a TBA contract out to a later date by entering into an offsetting short position (referred to as a “pair off”), net settling the paired off positions for cash, and simultaneously purchasing a similar TBA contract for a later settlement date.  The Company records such pair offs on a gross basis such that there is a sale of the original TBA and a subsequent purchase of a new TBA.
Investment Valuation	Investment Valuation
	The Company has a pricing committee responsible for establishing valuation policies and procedures, as well as reviewing and approving valuations at a monthly pricing meeting. The pricing committee is composed of individuals from the accounting team, the investment team and senior management.
	Agency RMBS, Agency Debentures and U.S. Treasuries are generally valued based on prices provided by third-party services, as derived from such services’ pricing models. Inputs to the models may include, but are not limited to, reported trades, executable bid and ask prices, broker quotations, prices or yields of securities with similar characteristics, benchmark curves or information pertaining to the issuer, as well as industry and economic events. The pricing services may also use a matrix approach, which considers information regarding securities with similar characteristics to determine the valuation for a security.
	We generally value interest rate swaps and caps using prices provided by broker quotations. Such broker quotations are based on the present value of fixed and projected floating rate cash flows over the term of the swap contract. Future cash flows are discounted to their present value using swap rates provided by electronic data services or by brokers. No credit valuation adjustments were made in determining the fair value of the Company's interest rate swaps and caps.
	Fair values of long-lived assets, including real estate, are primarily derived internally, and are based on inputs observed from sales transactions of similar assets. For real estate, fair values are also based on comparable contemporaneous sales transactions and/or discounted cash flow estimates which reflect current and projected lease profiles and available industry information about capitalization rates and expected trends in rents and occupancy.
	All valuations from third-party pricing services or broker quotes are non-binding. We review all prices during our pricing process. To date, the Company has not adjusted any of the prices received from third-party pricing services or brokers. Our pricing review includes comparisons of similar market transactions, alternative third-party pricing services and broker quotes, or comparisons to a pricing model. To ensure the proper fair value hierarchy, the Company reviews the third-party pricing services methodology periodically to understand whether observable or unobservable inputs are being used. See Note 8, Fair Value Measurements, for a discussion of how the Company values its assets.
Investments in Securities	Investments in Securities
	The Company's investment securities are accounted for in accordance with Accounting Standards Codification ("ASC") 320—Investments in Debt and Equity Securities. The Company has chosen to make a fair value election pursuant to ASC 825—Financial Instruments for its securities and, therefore, our investment securities are recorded at fair market value on the consolidated balance sheets. The periodic changes in fair market value are recorded in current period earnings on the consolidated statements of operations as a component of net unrealized gain (loss) on investments. These investments generally meet the requirements to be classified as available-for-sale under ASC 320, which requires the securities to be carried at fair value on the balance sheet. Electing the fair value option permits the Company to record changes in fair value of our investments in the consolidated statements of operations, which in management’s view, more appropriately reflects the results of operations for a particular reporting period as all securities activities will be recorded in a similar manner.
	The Company records its transactions in securities on a trade date basis. We record realized gains and losses on securities transactions on an identified cost basis.
	The Company accounts for its investment in FHLB stock as a cost method investment in "Other Assets".
	Agency RMBS
	The Company’s investments in Agency RMBS consist of pass-through certificates backed by fixed-rate, monthly-reset adjustable-rate loans (“ARMs”) and hybrid ARMs, the principal and interest of which are guaranteed by Fannie Mae, Freddie Mac or Ginnie Mae. Hybrid ARMs have interest rates that have an initial fixed period (typically three, five, seven or ten years) and thereafter reset at regular intervals in a manner similar to ARMs.
	Forward Settling Transactions
	The Company engages in forward settling transactions to purchase certain securities. The Company records forward settling transactions on the trade date, and maintains security positions such that sufficient liquid assets will be available to make payment on the settlement date for the securities purchased. The Agency RMBS purchased at the forward settlement date are typically priced at a discount to securities for settlement in the current month. Securities purchased on a forward settling basis are carried at fair value and begin earning interest on the settlement date. Gains or losses may occur on these transactions due to changes in market conditions or the failure of counterparties to perform under the contract. Along with other forward settling transactions, the Company transacts in to-be-announced (“TBA”) securities. As with other forward settling transactions, a seller agrees to issue TBAs at a future date; however, the seller does not specify the particular securities to be delivered. Instead, the Company agrees to accept any security that meets specified terms such as issuer, interest rate and terms of underlying mortgages. The Company records TBAs on the trade date utilizing information associated with the specified terms of the transaction as opposed to the specific mortgages. TBAs are carried at fair value and begin earning interest on the settlement date. Gains or losses may occur due to the fact that the actual underlying mortgages received may be more or less favorable than those anticipated by the Company. See Note 7, Pledged Assets, for disclosure regarding the fair value of collateral pledged or received on forward settling transactions.
	At times, the Company may enter into TBA contracts as a means of investing in and financing Agency RMBS via “dollar roll” transactions.  TBA dollar roll transactions involve moving the settlement of a TBA contract out to a later date by entering into an offsetting short position (referred to as a “pair off”), net settling the paired off positions for cash, and simultaneously purchasing a similar TBA contract for a later settlement date.  The Company records such pair offs on a gross basis such that there is a sale of the original TBA and a subsequent purchase of a new TBA.
	Investment Valuation
	The Company has a pricing committee responsible for establishing valuation policies and procedures, as well as reviewing and approving valuations at a monthly pricing meeting. The pricing committee is composed of individuals from the accounting team, the investment team and senior management.
	Agency RMBS, Agency Debentures and U.S. Treasuries are generally valued based on prices provided by third-party services, as derived from such services’ pricing models. Inputs to the models may include, but are not limited to, reported trades, executable bid and ask prices, broker quotations, prices or yields of securities with similar characteristics, benchmark curves or information pertaining to the issuer, as well as industry and economic events. The pricing services may also use a matrix approach, which considers information regarding securities with similar characteristics to determine the valuation for a security.
	We generally value interest rate swaps and caps using prices provided by broker quotations. Such broker quotations are based on the present value of fixed and projected floating rate cash flows over the term of the swap contract. Future cash flows are discounted to their present value using swap rates provided by electronic data services or by brokers. No credit valuation adjustments were made in determining the fair value of the Company's interest rate swaps and caps.
	Fair values of long-lived assets, including real estate, are primarily derived internally, and are based on inputs observed from sales transactions of similar assets. For real estate, fair values are also based on comparable contemporaneous sales transactions and/or discounted cash flow estimates which reflect current and projected lease profiles and available industry information about capitalization rates and expected trends in rents and occupancy.
	All valuations from third-party pricing services or broker quotes are non-binding. We review all prices during our pricing process. To date, the Company has not adjusted any of the prices received from third-party pricing services or brokers. Our pricing review includes comparisons of similar market transactions, alternative third-party pricing services and broker quotes, or comparisons to a pricing model. To ensure the proper fair value hierarchy, the Company reviews the third-party pricing services methodology periodically to understand whether observable or unobservable inputs are being used. See Note 8, Fair Value Measurements, for a discussion of how the Company values its assets.
Interest Income
Repurchase Agreements and FHLB Advances	Repurchase Agreements and FHLB Advances
	Borrowings under repurchase agreements ("repo borrowings") and FHLB advances are collateralized by the Company’s Agency RMBS and U.S. Treasuries (collectively, "Debt Securities") and carried at their amortized cost, which approximates their fair value due to their short-term nature (generally 30-90 days). The Company’s repurchase agreement counterparties are institutional dealers in fixed income securities and large financial institutions, and in the case of FHLB advances, the FHLB of Cincinnati. Collateral under repurchase agreements and FHLB advances are valued daily and counterparties may require additional collateral when the fair value of the collateral declines. Counterparties have the right to sell or repledge collateral pledged under repurchase agreements and the FHLB advances agreement. See Note 5, Repurchase Agreements.
	We account for our repo borrowings and FHLB advances as short-term indebtedness under ASC 470—Debt; accordingly, these short-term instruments are accounted for in our financial statements at carrying value, or historic cost.
Interest Rate Swap And Cap Contracts	Interest Rate Swap and Cap Contracts
	We account for our interest rate swap and cap contracts transactions under ASC 815—Derivatives and Hedging. The Company uses interest rate swaps and interest rate caps to hedge a portion of its exposure to market risks, including interest rate risk, credit risk and extension risk. The objective of our risk management strategy is to reduce fluctuations in stockholders’ equity over a range of interest rate scenarios. In particular, we attempt to manage the risk of the cost of our variable rate liabilities increasing during a period of rising interest rates.
	During the term of an interest rate swap or cap, the Company makes or receives periodic payments and records unrealized gains or losses as a result of marking the swap or cap to their fair value. When the Company terminates a swap or cap, we record a realized gain or loss equal to the difference between the proceeds from (or cost of) the closing transaction and the Company's cost basis in the contract, if any. We report the periodic payments and amortization of premiums on cap contracts under interest expense in the consolidated statements of operations. Swaps involve a risk that interest rates will move contrary to the Company’s expectations, thereby increasing the Company’s payment obligation.
	The Company's interest rate swap and cap contracts may be subject to a master netting arrangement ("MNA"). The Company is exposed to credit loss in the event of non-performance by the counterparty to the swap or cap limited to the fair value of collateral posted in excess of the fair value of the contract in a net liability position and the shortage of the fair value of collateral posted for the contract in a net asset position. As of March 31, 2015 and December 31, 2014, the Company did not anticipate non-performance by any counterparty. Should interest rates move unexpectedly, the Company may not achieve the anticipated benefits of the interest rate swap or cap and may realize a loss.
	While the Company's derivative agreements generally permit for netting or setting off derivative assets and liabilities with the counterparty, the Company reports related assets and liabilities on a gross basis in our consolidated balance sheets. Derivative instruments in a gain position are reported as derivative assets at fair value and derivative instruments in a loss position are reported as derivative liabilities at fair value in our consolidated balance sheets. We record changes in fair value of our derivative instruments in net unrealized gain (loss) on swap and cap contracts in our consolidated statements of operations. Cash receipts and payments related to derivative instruments are classified in our consolidated statements of cash flows in accordance with U.S. GAAP in both the operating and investing activities sections in the Company’s consolidated statement of cash flows. See Note 4, Investments in Interest Rate Swap and Cap Contracts.

Investments_in_Securities_Tabl

Investments in Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Available-for-sale Securities [Abstract]
Available-for-sale Securities
	March 31, 2015
	Asset Type		Amortized Cost				Gross Unrealized Loss			Gross Unrealized Gain		Fair Value
	Fannie Mae Certificates
	Fixed Rate		$	12,326,027			$	(281	)	$	201,906	$	12,527,652
	ARMs		597,368				(1		)	8,959		606,326
	Total Fannie Mae		12,923,395				(282		)	210,865		13,133,978
	Freddie Mac Certificates
	Fixed Rate		1,211,409				(98		)	26,432		1,237,743
	ARMs		119,673				(221		)	1,808		121,260
	Total Freddie Mac		1,331,082				(319		)	28,240		1,359,003
	Ginnie Mae Certificates - ARMs		61,298				—			1,665		62,963
	U.S. Treasuries		497,553				—			3,781		501,334
	Other Investments		6,945				—			1,080		8,025
	Total		$	14,820,273			$	(601	)	$	245,631	$	15,065,303
	December 31, 2014
	Fannie Mae Certificates
	Fixed Rate		$	11,356,716			$	(2,984	)	$	158,571	$	11,512,303
	ARMs		1,282,065				(13,144		)	4,449		1,273,370
	Total Fannie Mae		12,638,781				(16,128		)	163,020		12,785,673
	Freddie Mac Certificates
	Fixed Rate		1,183,764				—			25,769		1,209,533
	ARMs		394,726				(6,753		)	1,144		389,117
	Total Freddie Mac		1,578,490				(6,753		)	26,913		1,598,650
	Ginnie Mae Certificates - ARMs		66,390				—			1,743		68,133
	U.S. Treasuries		149,585				(534		)	—		149,051
	Other Investments		6,945				—			1,080		8,025
	Total		$	14,440,191			$	(23,415	)	$	192,756	$	14,609,532
	The following table presents the gross unrealized loss and fair values of our available-for-sale Agency RMBS by length of time that such securities have been in a continuous unrealized loss position as of March 31, 2015 and December 31, 2014 (in thousands):
			Unrealized loss positions for
			Less than 12 Months							Greater than 12 months					Total
	As of		Fair value				Unrealized loss			Fair value		Unrealized loss			Fair value		Unrealized loss
	March 31, 2015		$	258,991			$	(380	)	$	97,643	$	(221	)	$	356,634	$	(601	)
	December 31, 2014		259,291				(577		)	1,494,884		(22,838		)	1,754,175		(23,415		)
	The following table is a summary of our net realized gain (loss) from the sale of available-for-sale investments for the three months ended March 31, 2015 and 2014 (in thousands):
		Three Months Ended March 31,
		2015				2014
	Available-for-sale investments, at cost	$	5,999,963			$	7,771,414
	Proceeds from available-for-sale investments sold	6,018,216				7,788,084
	Net gain on sale of available-for-sale investments	$	18,253			$	16,670
	Gross gain on sale of available-for-sale investments	$	33,979			$	51,142
	Gross loss on sale of available-for-sale investments	(15,726		)		(34,472		)
	Net gain on sale of available-for-sale investments	$	18,253			$	16,670
	The components of the carrying value of available-for-sale securities at March 31, 2015 and December 31, 2014 are presented below. The premium purchase price is due to the average coupon interest rates on these investments being higher than prevailing market rates, and conversely, the discount purchase price is due to the average coupon interest rates on these investments being lower than prevailing market rates.
	(in thousands)		March 31, 2015				December 31, 2014
	Principal balance		$	14,244,501			$	13,887,897
	Unamortized premium		578,370				552,869
	Unamortized discount		(2,598		)		(575		)
	Gross unrealized gains		245,631				192,756
	Gross unrealized losses		(601		)		(23,415		)
	Fair value		$	15,065,303			$	14,609,532

Investments_in_Interest_Rate_S1

Investments in Interest Rate Swap and Cap Contracts (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Interest Rate Derivatives [Table Text Block]	The Company had the following activity in interest rate swap and cap transactions during the three months ended March 31, 2015 and 2014 (in thousands):
	Three Months Ended March 31, 2015							Three Months Ended March 31, 2014
	Trade Date	Transaction		Notional				Trade Date		Transaction	Notional
	Jan-15	Terminated		$	(400,000	)		Feb-14		Terminated	$	(500,000	)
	Jan-15	Opened		500,000				Net Decrease			$	(500,000	)
	Net Increase			$	100,000
Schedule of Derivative Instruments	Below is a summary of our interest rate swap and cap contracts open as of March 31, 2015 and December 31, 2014 (in thousands):
	Derivatives not designated as hedging instruments under ASC 815
	Interest Rate Swap Contracts	Notional				Fair Value				Consolidated Balance Sheets
	March 31, 2015	$	4,000,000			$	(38,502	)		Derivative liabilities, at fair value
	March 31, 2015	3,750,000				11,333				Derivative assets, at fair value
	December 31, 2014	2,600,000				(16,007		)		Derivative liabilities, at fair value
	December 31, 2014	5,050,000				40,611				Derivative assets, at fair value
	Interest Rate Cap Contracts	Notional				Fair Value				Consolidated Balance Sheets
	March 31, 2015	$	2,500,000			$	80,271			Derivative assets, at fair value
	December 31, 2014	2,500,000				107,673				Derivative assets, at fair value
	The following table presents information about the net realized and unrealized gain and loss on swap and cap contracts for the three months ended March 31, 2015 and 2014 on the Company's interest rate swap and cap contracts not designated as hedging instruments under ASC 815 (in thousands):
				Amount Recognized in Income on Derivatives
				Three Months Ended March 31,
	Derivative Type	Location of Gain or (Loss) Recognized in Income on Derivative		2015				2014
	Interest rate swaps and caps	Net realized gain (loss) on termination of swap and cap contracts		$	(2,568	)		$	(9,323	)
	Interest rate swaps and caps	Net unrealized gain (loss) on swap and cap contracts		(74,800		)		(16,240		)
	Interest rate swaps and caps	Total recognized in income on derivatives		$	(77,368	)		$	(25,563	)
	We continue to reposition our hedges, and in January 2015 entered into a 7-year $500 million notional swap at a pay rate of 2.15%, cancelable in January 2016, and at the same time we terminated a 7-year $400 million notional interest rate swap at a pay rate of 2.416%, cancelable in June 2015.
	At March 31, 2015 and December 31, 2014, the Company's derivative assets and liabilities (by type) are as follows (in thousands):
	March 31, 2015	Assets				Liabilities
	Interest rate swap contracts	$	11,333			$	38,502
	Interest rate cap contracts	80,271				—
	Total derivative assets and liabilities in the interim consolidated balance sheet	91,604				38,502
	Derivatives not subject to an MNA	843				30,684
	Total assets and liabilities subject to an MNA	$	90,761			$	7,818
	December 31, 2014	Assets				Liabilities
	Interest rate swap contracts	$	40,611			$	16,007
	Interest rate cap contracts	107,673				—
	Total derivative assets and liabilities in the interim consolidated balance sheet	148,284				16,007
	Derivatives not subject to an MNA	7,008				11,579
	Total assets and liabilities subject to an MNA	$	141,276			$	4,428

Repurchase_Agreements_and_FHLB1

Repurchase Agreements and FHLB Advances (Tables)	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Schedule Of Company's Borrowings	Certain information with respect to the Company’s repo borrowings and FHLB advances outstanding at the balance sheet date is summarized in the table below. Each of the repo borrowings and the FHLB advances are contractually due in one year or less.
	(in thousands)	March 31, 2015			December 31, 2014
	Outstanding repurchase agreements	$	10,204,901		$	11,289,559
	Outstanding FHLB advances	$	510,000		$	—
	Interest accrued thereon	$	3,574		$	5,334
	Weighted-average borrowing rate(1)	0.34		%	0.35		%
	Weighted-average remaining maturity (in days)	43.6			28.2
	Fair value of the collateral(2)	$	11,212,170		$	11,842,427

Pledged_Assets_Tables

Pledged Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Transfers and Servicing [Abstract]
Assets Pledged to Counterparties	The following tables summarize our assets pledged as collateral under our repo borrowings, FHLB advances, and derivative agreements by type, including securities pledged related to securities purchased or sold but not yet settled, as of March 31, 2015 and December 31, 2014 (in thousands):
	March 31, 2015
	Assets Pledged to Counterparties		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	10,752,304			$	56,339			$	991			$	10,809,634
	U.S. Treasuries - fair value		476,142				24,204				—				500,346
	Accrued interest on pledged securities		29,790				245				2				30,037
	Cash		—				37,216				—				37,216
	Total		$	11,258,236			$	118,004			$	993			$	11,377,233
	December 31, 2014
	Assets Pledged to Counterparties		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	11,697,532			$	42,894			$	1,453			$	11,741,879
	U.S. Treasuries - fair value		149,051				17,992				—				167,043
	Accrued interest on pledged securities		31,475				168				3				31,646
	Cash		—				11,104				—				11,104
	Total		$	11,878,058			$	72,158			$	1,456			$	11,951,672
Assets Pledged from Counterparties	As of March 31, 2015 and December 31, 2014, we also had assets pledged to us as collateral under our repurchase and derivative agreements summarized in the tables below (in thousands):
	March 31, 2015
	Assets Pledged to CYS		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	5,154			$	15,787			$	646			$	21,587
	U.S. Treasuries - fair value		11,122				18,805				—				29,927
	Accrued interest on pledged securities		82				85				2				169
	Cash		—				47,670				559				48,229
	Total		$	16,358			$	82,347			$	1,207			$	99,912
	December 31, 2014
	Assets Pledged to CYS		Repurchase Agreements				Derivative Instruments				Forward Settling Trades (TBAs)				Total
	Agency RMBS - fair value		$	3,464			$	22,112			$	3,225			$	28,801
	U.S. Treasuries - fair value		692				25,115				—				25,807
	Accrued interest on pledged securities		13				142				9				164
	Cash		—				71,980				791				72,771
	Total		$	4,169			$	119,349			$	4,025			$	127,543
Schedule of Derivative Instruments	Below is a summary of our interest rate swap and cap contracts open as of March 31, 2015 and December 31, 2014 (in thousands):
	Derivatives not designated as hedging instruments under ASC 815
	Interest Rate Swap Contracts		Notional				Fair Value				Consolidated Balance Sheets
	March 31, 2015		$	4,000,000			$	(38,502	)		Derivative liabilities, at fair value
	March 31, 2015		3,750,000				11,333				Derivative assets, at fair value
	December 31, 2014		2,600,000				(16,007		)		Derivative liabilities, at fair value
	December 31, 2014		5,050,000				40,611				Derivative assets, at fair value
	Interest Rate Cap Contracts		Notional				Fair Value				Consolidated Balance Sheets
	March 31, 2015		$	2,500,000			$	80,271			Derivative assets, at fair value
	December 31, 2014		2,500,000				107,673				Derivative assets, at fair value
	The following table presents information about the net realized and unrealized gain and loss on swap and cap contracts for the three months ended March 31, 2015 and 2014 on the Company's interest rate swap and cap contracts not designated as hedging instruments under ASC 815 (in thousands):
					Amount Recognized in Income on Derivatives
					Three Months Ended March 31,
	Derivative Type		Location of Gain or (Loss) Recognized in Income on Derivative		2015				2014
	Interest rate swaps and caps		Net realized gain (loss) on termination of swap and cap contracts		$	(2,568	)		$	(9,323	)
	Interest rate swaps and caps		Net unrealized gain (loss) on swap and cap contracts		(74,800		)		(16,240		)
	Interest rate swaps and caps		Total recognized in income on derivatives		$	(77,368	)		$	(25,563	)
	We continue to reposition our hedges, and in January 2015 entered into a 7-year $500 million notional swap at a pay rate of 2.15%, cancelable in January 2016, and at the same time we terminated a 7-year $400 million notional interest rate swap at a pay rate of 2.416%, cancelable in June 2015.
	At March 31, 2015 and December 31, 2014, the Company's derivative assets and liabilities (by type) are as follows (in thousands):
	March 31, 2015		Assets				Liabilities
	Interest rate swap contracts		$	11,333			$	38,502
	Interest rate cap contracts		80,271				—
	Total derivative assets and liabilities in the interim consolidated balance sheet		91,604				38,502
	Derivatives not subject to an MNA		843				30,684
	Total assets and liabilities subject to an MNA		$	90,761			$	7,818
	December 31, 2014		Assets				Liabilities
	Interest rate swap contracts		$	40,611			$	16,007
	Interest rate cap contracts		107,673				—
	Total derivative assets and liabilities in the interim consolidated balance sheet		148,284				16,007
	Derivatives not subject to an MNA		7,008				11,579
	Total assets and liabilities subject to an MNA		$	141,276			$	4,428
Offsetting Assets	Below is a summary of the Company's assets subject to offsetting provisions (in thousands):
									Gross Amounts Not Offset in the Consolidated Balance Sheet
	As of		Description		Amounts of Assets Presented in the Consolidated Balance Sheet				Instruments Available for Offset				Collateral Received(1)				Net Amount(2)
	March 31, 2015		Derivative assets		$	90,761			$	2,546			$	79,995			$	8,220
	December 31, 2014		Derivative assets		141,276				4,341				117,991				18,944
	_________________
	-1	Collateral consists of Agency RMBS, U.S. Treasuries and cash. Excess collateral received is not shown for financial reporting purposes.
	-2	Net amount represents the net amount receivable from the counterparty in the event of default.
Offsetting Liabilities	Below is a summary of the Company's liabilities subject to offsetting provisions (in thousands):
									Gross Amounts Not Offset in the Consolidated Balance Sheet
	As of		Description		Amounts of Liabilities Presented in the Consolidated Balance Sheet				Instruments Available for Offset				Collateral Pledged(1)				Net Amount(2)
	March 31, 2015		Derivative liabilities		$	7,818			$	2,546			$	5,272			$	—
	March 31, 2015		Repurchase agreements		10,204,901				—				10,204,901				—
	31-Dec-14		Derivative liabilities		$	4,428			$	4,341			$	87			$	—
	31-Dec-14		Repurchase agreements		11,289,559				—				11,289,559				—
	_______________
	-1	Collateral consists of Agency RMBS, U.S. Treasuries and Cash. Excess collateral pledged is not shown for financial reporting purposes.
	-2	Net amount represents the net amount payable to the counterparty in the event of default.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables provide a summary of the Company’s assets and liabilities that are measured at fair value, and recorded and presented at fair value as of March 31, 2015 and December 31, 2014 (in thousands):
	March 31, 2015	Fair Value Measurements Using
		Level 1		Level 2		Level 3		Total
	Assets
	Agency RMBS	$	—	$	14,555,943	$	—	$	14,555,943
	U.S. Treasuries	501,335		—		—		501,335
	Other Investments					8,025		8,025
	Derivative assets	—		91,604		—		91,604
	Total	$	501,335	$	14,647,547	$	8,025	$	15,156,907
	Liabilities
	Derivative liabilities	$	—	$	38,502	$	—	$	38,502
	December 31, 2014	Fair Value Measurements Using
		Level 1		Level 2		Level 3		Total
	Assets
	Agency RMBS	$	—	$	14,452,456	$	—	$	14,452,456
	U.S. Treasuries	149,051		—		—		149,051
	Other investments	—		—		8,025		8,025
	Derivative assets	—		148,284		—		148,284
	Total	$	149,051	$	14,600,740	$	8,025	$	14,757,816
	Liabilities
	Derivative liabilities	$	—	$	16,007	$	—	$	16,007
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	Level 3 Fair Value Reconciliation
	(In thousands)	Three Months Ended March 31,
	Other investments	2015		2014
	Beginning balance Level 3 assets	$	8,025	$	6,945
	Cash payments recorded as a reduction of cost basis	—		—
	Change in net unrealized gain (loss)	—		—
	Gross purchases	—		—
	Gross sales	—		—
	Net gain (loss) on sales	—		—
	Transfers into (out of) Level 3	—		—
	Ending balance Level 3 assets	$	8,025	$	6,945

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule Of Computation Of Basic And Diluted Earnings Per Share	Components of the computation of basic and diluted earnings per share ("EPS") were as follows (in thousands except per share amounts):
		Three Months Ended March 31,
		2015			2014
	Net income (loss)	$	54,597		$	130,687
	Less preferred stock dividends	(5,203		)	(5,203		)
	Net income (loss) available to common stockholders	49,394			125,484
	Less dividends paid:
	Common shares	(47,110		)	(51,515		)
	Unvested shares	(324		)	(334		)
	Undistributed earnings (loss)	1,960			73,635
	Basic weighted-average shares outstanding:
	Common shares	159,573			160,936
	Basic earnings (loss) per common share:
	Distributed earnings	$	0.3		$	0.32
	Undistributed earnings (loss)	0.01			0.46
	Basic earnings (loss) per common share	$	0.31		$	0.78
	Diluted weighted-average shares outstanding:
	Common shares	159,573			160,936
	Net effect of dilutive stock options (1)	—			—
		159,573			160,936
	Diluted earnings (loss) per common share:
	Distributed earnings	$	0.3		$	0.32
	Undistributed earnings (loss)	0.01			0.46
	Diluted earnings (loss) per common share	$	0.31		$	0.78
	__________________
	-1	For the three months ended March 31, 2015 and 2014, the Company had an aggregate of 131,088 stock options outstanding with a weighted-average exercise price of $30.00 that were not included in the calculation of EPS, as their inclusion would have been anti-dilutive. These instruments may have a dilutive impact on future EPS.

Organization_Details

Organization (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Series A Cumulative Redeemable Preferred Stock, liquidation preference per share	$25	$25

Significant_Accounting_Policie2

Significant Accounting Policies (Details)	3 Months Ended
	Mar. 31, 2015
Minimum [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Period	30 days
Maximum [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Period	90 days

Investments_in_Securities_Deta

Investments in Securities (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale Securities [Abstract]
WeightedAverageCouponDebtSecurities	3.38%	3.39%
U.S. Treasury Security Maturity Date	2019
Debt Instrument, Maturity Date	30 years
Agency RMBS Maturity Date Min	2024	2024
Agency RMBS Maturity Date Max	2045	2045
U.S. Treasury Securities Maturity Date Min	2018
U.S. Treasury Securities Maturity Date Max	2020

Investments_in_Securities_Avai

Investments in Securities (Available-for-sale securities by GSE Agency and Coupon) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	($601)	($23,415)
Gross unrealized gains	245,631	192,756
Fair value	15,065,303	14,609,532
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	12,923,395	12,638,781
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-282	-16,128
Gross unrealized gains	210,865	163,020
Fair value	13,133,978	12,785,673
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Fixed Rate Residential Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	12,326,027	11,356,716
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-281	-2,984
Gross unrealized gains	201,906	158,571
Fair value	12,527,652	11,512,303
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member] | Adjustable Rate Residential Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	597,368	1,282,065
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-1	-13,144
Gross unrealized gains	8,959	4,449
Fair value	606,326	1,273,370
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,331,082	1,578,490
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-319	-6,753
Gross unrealized gains	28,240	26,913
Fair value	1,359,003	1,598,650
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member] | Fixed Rate Residential Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,211,409	1,183,764
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-98	0
Gross unrealized gains	26,432	25,769
Fair value	1,237,743	1,209,533
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member] | Adjustable Rate Residential Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	119,673	394,726
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-221	-6,753
Gross unrealized gains	1,808	1,144
Fair value	121,260	389,117
Government National Mortgage Association Certificates and Obligations (GNMA) [Member] | Adjustable Rate Residential Mortgage [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	61,298	66,390
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0	0
Gross unrealized gains	1,665	1,743
Fair value	62,963	68,133
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	497,553	149,585
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0	-534
Gross unrealized gains	3,781	0
Fair value	501,334	149,051
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	6,945	6,945
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0	0
Gross unrealized gains	1,080	1,080
Fair value	8,025	8,025
Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	14,820,273	14,440,191
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	-601	-23,415
Gross unrealized gains	245,631	192,756
Fair value	$15,065,303	$14,609,532

Investments_in_Securities_Avai1

Investments in Securities (Available for sale, Continuous Unrealized Loss) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$258,991	$259,291
Unrealized loss on investments, owned less than 12 months	-380	-577
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	97,643	1,494,884
Unrealized loss on investments, owned more than 12 months	-221	-22,838
Fair value of investments in unrealized loss position	356,634	1,754,175
Available for sale securities, continuous unrealized loss	($601)	($23,415)

Investments_in_Securities_Summ

Investments in Securities (Summary of Net Gain (loss) from the Sale of Available-for-Sale Investments) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Available-for-sale investments, at cost	$5,999,963	$7,771,414
Proceeds from available-for-sale investments sold	6,018,216	7,788,084
Net gain on sale of available-for-sale investments	18,253	16,670
Gross gain on sale of available-for-sale investments	33,979	51,142
Gross loss on sale of available-for-sale investments	($15,726)	($34,472)

Investments_in_Securities_Comp

Investments in Securities (Components of the Carrying Value of Available-for-Sale Securities) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Principal balance	$14,244,501	$13,887,897
Unamortized premium	578,370	552,869
Unamortized discount	-2,598	-575
Gross unrealized gains	245,631	192,756
Gross unrealized losses	-601	-23,415
Fair value	15,065,303	14,609,532
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	12,923,395	12,638,781
Gross unrealized gains	210,865	163,020
Gross unrealized losses	-282	-16,128
Fair value	13,133,978	12,785,673
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,331,082	1,578,490
Gross unrealized gains	28,240	26,913
Gross unrealized losses	-319	-6,753
Fair value	1,359,003	1,598,650
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	497,553	149,585
Gross unrealized gains	3,781	0
Gross unrealized losses	0	-534
Fair value	$501,334	$149,051

Investments_in_Interest_Rate_S2

Investments in Interest Rate Swap and Cap Contracts (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Trading Securities Pledged as Collateral	$80.50	$60.90
Securities Received as Collateral	34.6	47.2
Derivative, Collateral, Obligation to Return Cash	47.7	72
SwapOpenedJanuaryTwoThousandFifteenNotional	500
SwapOpenedJanuaryTwoThousandFifteenPayRate	2.15%
SwapTerminatedJanuaryTwoThousandFifteenNotional	$400
SwapTerminatedJanuaryTwoThousandFifteenPayRate	2.42%

Investments_in_Interest_Rate_S3

Investments in Interest Rate Swap and Cap Contracts (Summary Of Interest Rate Swap And Cap Contracts) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Transaction And Trade Date [Line Items]
DerivativeNotionalTransactions	$100,000	($500,000)
JanuaryTwoThousandAndFifteenTerminated [Member]
Transaction And Trade Date [Line Items]
Trade Date Of Interest Rate Swap And Cap Contracts	Jan-15
DerivativeNotionalTransactions	-400,000
FebruaryTwoThousandFourteenTerminated [Member]
Transaction And Trade Date [Line Items]
Trade Date Of Interest Rate Swap And Cap Contracts		Feb-14
DerivativeNotionalTransactions		-500,000
JanuaryTwoThousandAndFifteenOpened [Member]
Transaction And Trade Date [Line Items]
Trade Date Of Interest Rate Swap And Cap Contracts	Jan-15
DerivativeNotionalTransactions	$500,000

Investments_in_Interest_Rate_S4

Investments in Interest Rate Swap and Cap Contracts (Derivatives not designated as hedging activities under ASC 815) (Details) (Derivatives Not Designated As Hedging Instruments [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Interest Rate Swap [Member] | Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$3,750,000	$5,050,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	11,333	40,611
Interest Rate Swap [Member] | Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4,000,000	2,600,000
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	-38,502	-16,007
Interest Rate Cap [Member] | Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,500,000	2,500,000
Derivative Asset, Fair Value, Gross Asset	$80,271	$107,673

Investments_in_Interest_Rate_S5

Investments in Interest Rate Swap and Cap Contracts (Amount recognized in income on derivatives) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net realized gain (loss) on termination of swap and cap contracts	($2,568)	($9,323)
Net unrealized gain (loss) on swap and cap contracts	-74,800	-16,240
Derivative, Gain (Loss) on Derivative, Net	($77,368)	($25,563)

Repurchase_Agreements_and_FHLB2

Repurchase Agreements and FHLB Advances (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified	D		D
Short-term Debt [Line Items]
Repopercentageofstockholdersequity	1.60%		1.60%
RepoBorrowingsandFHLBadvancesaspercentageoftotalassets	4.00%
Outstanding repurchase agreements	$10,204,901		$11,289,559	[1]
FHLB advances	510,000		0	[1]
Interest accrued thereon	3,574		5,334
Weighted average borrowing rate	0.34%	[2]	0.35%	[2]
ShortTermDebtWeightedAverageInterestRateUSTreasuries	0.04%
Weighted Average Remaining Maturity (In Days)	43.6		28.2
Fair value of the collateral(1)	$11,212,170	[3]	$11,842,427	[3]
Number of repurchase agreements exceeding 10% of net assets	0		0
Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets	1.50%		1.60%
[1]	Derived from audited financial statements.
[2]	(1)The weighted-average borrowing rate as of MarchB 31, 2015 was determined as set forth in the table below.CollateralBorrowing amountB RateAgency RMBS$10,243,805B 0.36B %U.S. Treasuries471,096B (0.04)%Total / weighted-average borrowing rate $10,714,901B 0.34B %
[3]	(2)Collateral for repo borrowings and FHLB advances consisted of Agency RMBS and U.S. Treasuries.

Repurchase_Agreements_and_FHLB3

Repurchase Agreements and FHLB Advances Schedule of Weighted Average Borrowing Rate (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]
SecuritiesSoldUnderAgreementsToRepurchaseAgencyRMBS	$10,243,805
ShortTermDebtWeightedAverageInterestRateAgencyRMBS	0.36%
Securities Sold under Agreements to Repurchase	-10,204,901		-11,289,559	[1]
Short-term Debt, Weighted Average Interest Rate	0.34%	[2]	0.35%	[2]
SecuritiesSoldUnderAgreementsToRepurchaseUSTreasuries	471,096
ShortTermDebtWeightedAverageInterestRateUSTreasuries	-0.04%
SecuritiesSoldUnderAgreementsExcludingFHLBAdvances	$10,714,901
ShortTermDebtWeightedAverageInterestRateExcludingFHLBAcvances	0.34%
[1]	Derived from audited financial statements.
[2]	(1)The weighted-average borrowing rate as of MarchB 31, 2015 was determined as set forth in the table below.CollateralBorrowing amountB RateAgency RMBS$10,243,805B 0.36B %U.S. Treasuries471,096B (0.04)%Total / weighted-average borrowing rate $10,714,901B 0.34B %

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Indemnification claims	$0	$0

Pledged_Assets_Assets_Pledged_

Pledged Assets (Assets Pledged to Counterparties) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	$11,377,233	$11,951,672
Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	10,809,634	11,741,879
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	500,346	167,043
Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	30,037	31,646
Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	37,216	11,104
Repurchase Agreements [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	11,258,236	11,878,058
Repurchase Agreements [Member] | Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	10,752,304	11,697,532
Repurchase Agreements [Member] | US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	476,142	149,051
Repurchase Agreements [Member] | Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	29,790	31,475
Repurchase Agreements [Member] | Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	0	0
Derivative [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	118,004	72,158
Derivative [Member] | Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	56,339	42,894
Derivative [Member] | US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	24,204	17,992
Derivative [Member] | Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	245	168
Derivative [Member] | Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	37,216	11,104
Forward Settling Trades [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	993	1,456
Forward Settling Trades [Member] | Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	991	1,453
Forward Settling Trades [Member] | US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	0	0
Forward Settling Trades [Member] | Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	2	3
Forward Settling Trades [Member] | Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral to Counterparties, at Fair Value	$0	$0

Pledged_Assets_Assets_Pledged_1

Pledged Assets (Assets Pledged from Counterparties ) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	$99,912	$127,543
Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	21,587	28,801
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	29,927	25,807
Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	169	164
Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	48,229	72,771
Repurchase Agreements [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	16,358	4,169
Repurchase Agreements [Member] | Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	5,154	3,464
Repurchase Agreements [Member] | US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	11,122	692
Repurchase Agreements [Member] | Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	82	13
Repurchase Agreements [Member] | Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	0	0
Derivative [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	82,347	119,349
Derivative [Member] | Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	15,787	22,112
Derivative [Member] | US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	18,805	25,115
Derivative [Member] | Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	85	142
Derivative [Member] | Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	47,670	71,980
Forward Settling Trades [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	1,207	4,025
Forward Settling Trades [Member] | Agency RMBS [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	646	3,225
Forward Settling Trades [Member] | US Treasury Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	0	0
Forward Settling Trades [Member] | Accrued Interest on Pledged Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	2	9
Forward Settling Trades [Member] | Cash [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Pledged as Collateral from Counterparties, at Fair Value	$559	$791

Pledged_Assets_Derivatives_Det

Pledged Assets (Derivatives) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Transfers and Servicing [Abstract]
Derivative Asset, Current	$11,333	$40,611
Derivative Liability, Current	38,502	16,007
Interest rate cap, asset position	80,271	107,673
Interest rate cap, liability position	0	0
Derivative Asset	91,604	148,284	[1]
Derivative liabilities, at fair value	38,502	16,007	[1]
Derivative Asset, Not Subject to Master Netting Arrangement	843	7,008
Derivative Liability, Not Subject to Master Netting Arrangement	30,684	11,579
DerivativeAssetSubjectToMasterNettingArrangement	90,761	141,276
DerivativeLiabilitySubjectToMasterNettingArrangement	$7,818	$4,428
[1]	Derived from audited financial statements.

Pledged_Assets_Offsetting_Asse

Pledged Assets (Offsetting Assets) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Transfers and Servicing [Abstract]
DerivativeAssetSubjectToMasterNettingArrangement	$90,761	$141,276
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	2,546	4,341
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	79,995	117,991
Derivative Asset, Fair Value, Amount Offset Against Collateral	$8,220	$18,944

Pledged_Assets_Offsetting_Liab

Pledged Assets (Offsetting Liabilities) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Transfers and Servicing [Abstract]
DerivativeLiabilitySubjectToMasterNettingArrangement	$7,818	$4,428
NetDerivativeLiability		4,428
InstrumentsAvailableToOffsetDerivativeLiability	2,546	4,341
Derivative Liability, Fair Value of Collateral	5,272	87
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	0
Outstanding repurchase agreements	10,204,901	11,289,559	[1]
InstrumentsAvailableToOffsetRepoLiability	0	0
SecuritiesSoldUnderAgreementsNotOffsetAgainstCollateral	$0	$0
[1]	Derived from audited financial statements.

Fair_Value_Measurements_Detail

Fair Value Measurements (Details)	Mar. 31, 2015
Fair Value Disclosures [Abstract]
unobservable input capitalization rate min	3.00%
unobservable input capitalization rate max	6.00%

Fair_Value_Measurements_Assets

Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Agency RMBS	$14,555,943	$14,452,456
US Treasury fair value disclosure	501,335	149,051
Other Investments	8,025	8,025
Derivative Asset	91,604	148,284	[1]
Assets, Fair Value Disclosure, Recurring	15,156,907	14,757,816
Derivative liabilities	38,502	16,007
Derivative liabilities, at fair value	38,502	16,007	[1]
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Agency RMBS	0	0
US Treasury fair value disclosure	501,335	149,051
Other Investments		0
Derivative Asset	0	0
Assets, Fair Value Disclosure, Recurring	501,335	149,051
Derivative liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Agency RMBS	14,555,943	14,452,456
US Treasury fair value disclosure	0	0
Other Investments		0
Derivative Asset		148,284
Assets, Fair Value Disclosure, Recurring	14,647,547	14,600,740
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Agency RMBS	0	0
US Treasury fair value disclosure	0	0
Other Investments	8,025	8,025
Derivative Asset	0	0
Assets, Fair Value Disclosure, Recurring	8,025	8,025
Derivative liabilities	$0	$0
[1]	Derived from audited financial statements.

Fair_Value_Measurements_Level_

Fair Value Measurements (Level 3 Fair Value Reconciliation) (Details) (Other Investments [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	$0	$0
Beginning balance Level 3 assets	8,025	6,945
Change in net unrealized gain (loss)	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0	0
Net gain (loss) on sales	0	0
Transfers into (out of) level 3	0	0
Ending balance Level 3 assets	$8,025	$6,945

Share_Capital_Details

Share Capital (Details) (USD $)	3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014	Dec. 31, 2014		Jul. 22, 2014	Nov. 15, 2012	Jun. 07, 2011
Equity Issuance [Line Items]
Common stock, shares authorized	500,000,000			500,000,000
Common stock, par value	$0.01			$0.01
Common Stock, Shares, Issued	158,114,483			161,849,878
Common Stock, Shares, Outstanding	158,114,483			161,849,878
Preferred Stock, Shares Authorized	50,000,000			50,000,000
Preferred Stock, Par or Stated Value Per Share	$0.01			$0.01
Preferred Stock, Shares Issued	3,000,000			3,000,000
Preferred Stock, Shares Outstanding	3,000,000			3,000,000
Preferred Stock B, Dividend Rate, Percentage 7.50%	7.50%
Series A Cumulative Redeemable Preferred Stock, liquidation preference per share	$25			$25
Preferred Stock A, Dividend Rate, Percentage 7.75%	7.75%
Series B Cumulative Redeemable Preferred Stock, shares outstanding	8,000,000			8,000,000
Series B Cumulative Redeemable Preferred Stock, shares issued	8,000,000			8,000,000
7.50% Series B Cumulative Redeemable Preferred Stock, (8,000 shares issued and outstanding, respectively, $200,000 in aggregate liquidation preference)	$193,531,000			$193,531,000	[1]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period	438,617	389,880
Number Of Common Stock Available To Sell Under Sales Agreement			134,300,000
Stock Repurchase Program, Authorized Amount						250,000,000	250,000,000
Treasury Stock Acquired, Average Cost Per Share	$8.95
Net proceeds (payments) from issuance and repurchase of common shares	37,200,000		115,700,000	1,500,000
Stock Repurchased and Retired During Period, Shares	4,149,571			172,549
July 2014 Repurchase Plan [Member]
Equity Issuance [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$211,200,000
Dividend Reinvestment And Direct Stock Purchase Plan [Member]
Equity Issuance [Line Items]
Stock Available For Issuance During Period Shares Dividend Reinvestment Plan	4,100,000			4,055,245
Equity Placement Program [Member]
Equity Issuance [Line Items]
Number Of Common Stock Available To Sell Under Sales Agreement				3,081,447				15,000,000
[1]	Derived from audited financial statements.

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$54,597		$130,687
Less preferred stock dividends	-5,203		-5,203
Net income (loss) available to common stockholders	49,394		125,484
Common shares	-47,110		-51,515
Unvested shares	-324		-334
Undistributed earnings (loss)	$1,960		$73,635
Common shares	159,573,000		160,936,000
Distributed earnings	$0.30		$0.32
Undistributed earnings (loss)	$0.01		$0.46
Basic earnings (loss) per common share	$0.31		$0.78
Net effect of dilutive stock options (1)	0	[1]	0	[1]
Diluted weighted average shares outstanding	159,573,000		160,936,000
Distributed earnings	$0.30		$0.32
Undistributed earnings (loss)	$0.01		$0.46
Diluted earnings (loss) per common share	$0.31		$0.78
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	131,088		131,088
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$30		$30
[1]	For the three months ended MarchB 31, 2015 and 2014, the Company had an aggregate of 131,088 stock options outstanding with a weighted-average exercise price of $30.00 that were not included in the calculation of EPS, as their inclusion would have been anti-dilutive. These instruments may have a dilutive impact on future EPS.

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	1 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Subsequent Event [Line Items]
FHLB advances		$510,000	$0	[1]
Restricted Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	21,303
[1]	Derived from audited financial statements.