Capstead Mortgage (CMO) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 27, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	CAPSTEAD MORTGAGE CORP
Entity Central Index Key	766701
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$1,238,555,013
Entity Common Stock, Shares Outstanding		95,812,050
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:
Residential mortgage investments ($13.48 and $13.12 billion pledged under repurchase arrangements at December 31, 2014 and December 31, 2013, respectively)	$13,908,104	$13,475,874
Cash collateral receivable from interest rate swap counterparties	53,139	25,502
Interest rate swap agreements at fair value	1,657	5,005
Cash and cash equivalents	307,526	413,356
Receivables and other assets	118,643	96,231
Total Assets	14,389,069	14,015,968
Liabilities:
Repurchase arrangements and similar borrowings	12,806,843	12,482,900
Interest rate swap agreements at fair value	27,034	11,304
Unsecured borrowings	100,000	100,000
Common stock dividend payable	34,054	30,872
Accounts payable and accrued expenses	30,367	25,109
Total Liabilities	12,998,298	12,650,185
Stockholders' equity:
Common stock - $0.01 par value; 250,000 shares authorized: 95,848 and 95,807 shares issued and outstanding at December 31, 2014 and December 31, 2013, respectively	958	958
Paid-in capital	1,325,340	1,329,792
Accumulated deficit	-346,885	-349,866
Accumulated other comprehensive income	227,422	219,143
Stockholders' Equity Attributable to Parent	1,390,771	1,365,783
Total Liabilities and Equity	14,389,069	14,015,968
Redeemable Preferred Stock [Member] | Cumulative Redeemable Preferred Stock, Series E [Member]
Stockholders' equity:
Cumulative Preferred Stock	$183,936	$165,756

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Residential mortgage investments	$13,480,000	$13,120,000
Preferred stock, par value (in dollars per share)	$0.10	$0.10
Preferred stock, shares authorized (in shares)	100,000	100,000
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized (in shares)	250,000	250,000
Common stock, shares issued (in shares)	95,848	95,807
Common stock, shares outstanding (in shares)	95,848	95,807
Redeemable Preferred Stock [Member] | Cumulative Redeemable Preferred Stock, Series E [Member]
Preferred stock, dividend rate (in hundredths)	7.50%
Preferred stock, shares issued (in shares)	7,618	6,861
Preferred stock, shares outstanding (in shares)	7,618	6,861
Preferred stock, aggregate liquidation preference	$190,454	$171,521

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income:
Residential mortgage investments	$226,749	$215,137	$255,931
Other	315	322	698
Interest Income	227,064	215,459	256,629
Interest expense:
Repurchase arrangements and similar borrowings	-65,155	-66,368	-69,101
Unsecured borrowings	-8,488	-8,736	-8,747
Interest expense	-73,643	-75,104	-77,848
Net interest income (expense)	153,421	140,355	178,781
Other revenue (expense):
Salaries and benefits	-4,112	-3,962	-4,055
Short-term incentive compensation	-2,115	-3,565	-5,043
Long term incentive compensation	-2,075	-1,814	-1,874
Other general and administrative expense	-4,157	-4,476	-4,271
Miscellaneous other revenue (expense)	-142	-300	-171
Operating expenses	-12,601	-14,117	-15,414
Income before equity in earnings of unconsolidated affiliates	140,820	126,238	163,367
Equity in earnings of unconsolidated affiliates	0	249	259
Net income	140,820	126,487	163,626
Net income available to common stockholders:
Net income	140,820	126,487	163,626
Less preferred stock dividends	-13,781	-17,536	-21,021
Less redemption preference premiums paid	0	-19,924	0
Net income (loss) available to common stockholders, basic, total	$127,039	$89,027	$142,605
Basic and diluted net income per common share	$1.33	$0.93	$1.50

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other comprehensive income (loss)
Net income	$140,820	$126,487	$163,626
Amounts related to available-for-sale securities:
Change in net unrealized gains	27,283	-101,001	91,750
Amounts related to cash flow hedges:
Change in net unrealized gains (losses)	-41,059	9,320	-22,262
Reclassification adjustment for amounts included in net income	22,055	16,914	19,882
Other comprehensive income (loss)	8,279	-74,767	89,370
Comprehensive income	$149,099	$51,720	$252,996

CONSOLIDATED_STATEMENTS_OF_STO

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)	Preferred Stock [Member]	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income [Member]	Total
In Thousands, unless otherwise specified
Beginning Balance at Dec. 31, 2011	$184,514	$883	$1,257,653	($354,883)	$204,540	$1,292,707
Net income	0	0	0	163,626	0	163,626
Change in unrealized gain on mortgage securities, net	0	0	0	0	91,750	91,750
Amounts related to cash flow hedges, net	0	0	0	0	-2,380	-2,380
Cash dividends:
Common	0	0	-1,785	-141,660	0	-143,445
Preferred	0	0	0	-21,021	0	-21,021
Redemption of convertible preferred stock						0
Conversion of preferred stock	-1	0	1	0	0	0
Additions to capital	4,479	109	146,362	0	0	150,950
Common stock repurchases	0	-30	-35,032	0	0	-35,062
Ending Balance at Dec. 31, 2012	188,992	962	1,367,199	-353,938	293,910	1,497,125
Net income	0	0	0	126,487	0	126,487
Change in unrealized gain on mortgage securities, net	0	0	0	0	-101,001	-101,001
Amounts related to cash flow hedges, net	0	0	0	0	26,234	26,234
Cash dividends:
Common	0	0	-13,830	-104,932	0	-118,762
Preferred	0	0	0	-17,536	0	-17,536
Redemption of convertible preferred stock	-187,109	0	-19,924	0	0	-207,033
Conversion of preferred stock	-1,883	2	1,881	0	0	0
Issuance of Series E preferred stock	165,756	0	0	0	0	165,756
Other additions to capital	0	0	1,752	53	0	1,805
Common stock repurchases	0	-6	-7,286	0	0	-7,292
Ending Balance at Dec. 31, 2013	165,756	958	1,329,792	-349,866	219,143	1,365,783
Net income	0	0	0	140,820	0	140,820
Change in unrealized gain on mortgage securities, net	0	0	0	0	27,283	27,283
Amounts related to cash flow hedges, net	0	0	0	0	-19,004	-19,004
Cash dividends:
Common	0	0	-6,365	-124,058	0	-130,423
Preferred	0	0	0	-13,781	0	-13,781
Redemption of convertible preferred stock						0
Issuance of Series E preferred stock	18,180	0	0	0	0	18,180
Other additions to capital	0	0	1,913	0	0	1,913
Ending Balance at Dec. 31, 2014	$183,936	$958	$1,325,340	($346,885)	$227,422	$1,390,771

CONSOLIDATED_STATEMENTS_OF_STO1

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY [Abstract]
Common per share (in dollars per share)	$1.36	$1.24	$1.49

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities:
Net income	$140,820	$126,487	$163,626
Noncash items:
Amortization of investment premiums	101,872	125,872	96,677
Amortization of equity-based awards	2,390	2,201	2,236
Other depreciation and amortization	137	162	195
Incentive compensation paid in shares of common stock	0	0	2,799
Change in measureable hedge ineffectiveness related to interest rate swap agreements designated as cash flow hedges	76	-168	-411
Gain on sales of foreclosed real estate	0	0	-273
Net change in receivables, other assets, accounts payable and accrued expenses	3,517	6,658	-919
Net cash provided by operating activities	248,812	261,212	263,930
Investing activities:
Purchases of residential mortgage investments	-3,307,963	-3,326,345	-4,384,866
Interest receivable acquired with the purchase of residential mortgage investments	-5,313	-5,559	-7,180
Proceeds from sales of foreclosed real estate	0	0	2,010
Principal collections on residential mortgage investments, including changes in mortgage securities principal remittance receivable	2,785,337	3,516,634	2,756,772
Net cash (used in) provided by investing activities	-527,939	184,730	-1,633,264
Financing activities:
Proceeds from repurchase arrangements and similar borrowings	128,594,880	136,909,245	127,808,676
Principal payments on repurchase arrangements and similar borrowings	-128,270,935	-137,210,576	-126,376,876
(Increase) decrease in cash collateral receivable from interest rate swap counterparties	-27,637	24,470	-1,467
Cash paid to redeem convertible preferred stock	0	-207,033	0
Common stock repurchases	0	-7,292	-35,062
Proceeds from capital raising activities:
Issuance of preferred stock	18,180	165,756	4,479
Issuance of common stock	0	0	142,035
Other capital stock transactions	-468	-410	-585
Dividends paid	-140,723	-132,191	-173,138
Net cash provided by (used in) financing activities	173,297	-458,031	1,368,062
Net change in cash and cash equivalents	-105,830	-12,089	-1,272
Cash and cash equivalents at beginning of year	413,356	425,445	426,717
Cash and cash equivalents at end of year	$307,526	$413,356	$425,445

BUSINESS

BUSINESS	12 Months Ended
	Dec. 31, 2014
BUSINESS [Abstract]
BUSINESS	NOTE 1 ¾ BUSINESS
	Capstead Mortgage Corporation operates as a self-managed real estate investment trust for federal income tax purposes (a “REIT”) and is based in Dallas, Texas.  Unless the context otherwise indicates, Capstead Mortgage Corporation, together with its subsidiaries, is referred to as “Capstead” or the “Company.”  Capstead earns income from investing in a leveraged portfolio of residential mortgage pass-through securities consisting almost exclusively of adjustable-rate mortgage (“ARM”) securities issued and guaranteed by government-sponsored enterprises, either Fannie Mae or Freddie Mac (together, the “GSEs”), or by an agency of the federal government, Ginnie Mae.  Residential mortgage pass-through securities guaranteed by the GSEs or Ginnie Mae, referred to as “Agency Securities,” are considered to have limited, if any, credit risk.

ACCOUNTING_POLICIES

ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2014
ACCOUNTING POLICIES [Abstract]
ACCOUNTING POLICIES	NOTE 2 ¾ ACCOUNTING POLICIES
	Basis of Presentation
	The consolidated financial statements include the accounts of Capstead Mortgage Corporation and its wholly-owned and majority-owned subsidiaries over which it exercises control.  Capstead also consolidates, if appropriate, any variable interest entities in which it holds an interest.  Common securities held by the Company in statutory trusts organized to issue long-term unsecured borrowings (prior to the dissolution of these trusts in December 2013 – see NOTE 5) were not considered variable interests at risk pursuant to variable interest entity accounting principles and were accounted for as investments in unconsolidated affiliates.  Investments in any unconsolidated affiliates are initially recorded at cost and subsequently adjusted for the Company’s equity in earnings and losses and cash contributions and distributions.  Intercompany balances and transactions are eliminated.  Prior year amounts related to equity-based compensation for employees (see NOTE 12) have been reclassified from Salary and benefits to Long-term incentive compensation in the Statements of Income.
	Recent Accounting Pronouncements
	In June 2014 the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2014-11, Transfers and Servicing:  Repurchase-to-Maturity Transactions, Repurchase Financings and Disclosures (“ASU 2014-11”).  ASU 2014-11 requires repurchase-to-maturity transactions to be accounted for as financings and eliminates existing guidance regarding so-called “linked transactions” between a buyer of securities and a seller that also provides related repurchase financings.  ASU 2014-11 also introduces new disclosure requirements and is effective for periods beginning after December 15, 2014.  The adoption of ASU 2014-11 by the Company is not expected to have any effect on its results of operations, financial condition, or cash flows.
	Use of Estimates
	The use of estimates is inherent in the preparation of financial statements.  Amortization of investment premiums on financial assets is based in part on estimates of future levels of mortgage prepayments, which are impacted by future changes in interest rates and other factors.  While the actual level of mortgage prepayments for a given accounting period is the single largest determinant in amortizing investment premiums, if expectations for future levels of mortgage prepayments increase substantially, earnings could be adversely affected.
	Fair values of financial instruments are estimated based on a market approach using available market information and appropriate valuation methodologies (Level Two Inputs); however, judgment is required in interpreting market data to develop these estimates.  Fair values fluctuate on a daily basis and are influenced by changes in, and market expectations for changes in, interest rates, market liquidity conditions and levels of mortgage prepayments, as well as other factors.  Accordingly, estimates of fair value are as of the balance sheet dates and are not necessarily indicative of the amounts that could be realized in a current market exchange.  The use of different market assumptions and estimation methodologies may have a material effect on estimated fair values.  Judgment is also exercised in making impairment conclusions and estimating impairment charges.
	Cash and Cash Equivalents
	Cash and cash equivalents include unrestricted cash on hand and highly liquid investments with original maturities of three months or less when purchased.
	Financial Assets
	Capstead’s financial assets consist almost exclusively of Agency Securities classified as available-for-sale and carried at fair value with unrealized gains and losses reported as a separate component of Accumulated other comprehensive income.  Loans classified as held for investment or mortgage securities classified as held-to-maturity are recorded at amortized cost (unpaid principal balance, adjusted for unamortized investment premiums and discounts).  Interest is recorded as income when earned.  Investment premiums and discounts are recognized as adjustments to interest income by the interest method, generally over the expected life of the related financial assets. Realized gains and losses from sales are recorded as a component of Other revenue (expense).  The specific identification method is used to determine the cost of financial assets sold.  Financial assets are reviewed for potential impairment at each balance sheet date.  Other-than-temporary impairments of investments in mortgage securities can occur with changes in the Company’s intent or ability to hold the mortgage securities until any declines in fair value are recovered and as a result of adverse changes in the financial condition of the issuer(s) such that a full recovery of cost basis is no longer expected.  The amount of any such other-than-temporary impairment for an investment in a mortgage security is measured by comparing the recorded amount of the security to its fair value.  Other-than-temporary impairment charges would be recorded as a component of Other revenue (expense) if the impairment results from changes in in the Company’s intent or ability to hold the securities.  Should other-than-temporary impairment arise as a result of adverse changes in the financial condition of the issuer(s) without changing the Company’s intent and ability to hold the securities, the credit component of the impairment would be recorded as a component of Other revenue (expense) and with any remainder recorded as a component of Other comprehensive income.
	Borrowings
	Capstead’s borrowings are carried at their principal balances outstanding.  Debt issue costs associated with Unsecured borrowings are recorded in Receivables and other assets, and are recognized as adjustments to interest expense by the interest method over the term of these borrowings.
	Borrowings under repurchase arrangements create exposure to the potential for failure on the part of counterparties to honor their commitment to return pledged collateral.  In the event of a default by a counterparty, the Company may have difficulty recovering its collateral.  To mitigate this risk, the Company monitors the creditworthiness of its counterparties and manages its exposure to any single counterparty.
	Derivative Financial Instruments (“Derivatives”)
	Derivatives used by Capstead for risk management purposes are carried at fair value as assets or liabilities.  The accounting for changes in fair value of each Derivative held depends on whether it has been designated as a hedge for accounting purposes, as well as the type of hedging relationship identified.  Capstead will typically designate any Derivatives held as cash flow hedges related to a designated portion of its current and anticipated future borrowings.  To qualify as a cash flow hedge, at the inception of the hedge relationship the Company must document that the hedge relationship is anticipated to be highly effective and monitor ongoing effectiveness on at least a quarterly basis.  As long as the hedge relationship remains effective, the effective portion of changes in fair value of the Derivative is recorded in Accumulated other comprehensive income and the ineffective portion is recorded in interest expense.  The effective portion of changes in fair value is reclassified from Accumulated other comprehensive income to earnings over the term of the Derivative primarily in the form of Derivative cash flows that are either in excess of or lower than market rates.  Changes in fair value of Derivatives not held as accounting hedges, if any, or for which the hedge relationship is no longer considered highly effective, are recorded in Miscellaneous other revenue (expense).
	The Company uses interest rate swap agreements in cash flow hedge relationships in order to hedge variability in borrowing rates due to changes in the underlying benchmark interest rate related to a designated portion of its current and anticipated future borrowings.  Variable-rate swap payments to be received and any measured hedge ineffectiveness are recorded in interest expense as an offset to interest owed on the hedged borrowings that reset to market rates generally every 30 to 90 days.  Fixed-rate swap payments to be made are also recorded in interest expense.  The combination of these cash flows results in a relatively fixed rate on these borrowings, subject to certain adjustments.  These adjustments include changes in spreads between variable rates on the swap agreements and actual borrowing rates as well as the effects of measured hedge ineffectiveness.
	Holding Derivatives creates exposure to credit risk related to the potential for failure on the part of counterparties to honor their commitments.  In addition, the Company is required to post collateral based on any declines in the market value of the Derivatives.  In the event of default by a counterparty, the Company may have difficulty recovering its collateral and may not receive payments provided for under the terms of the Derivative.  To mitigate this risk, the Company uses only well-established commercial banks as counterparties and, pursuant to recent regulatory changes, most Derivatives held at December 31, 2014 were entered into through exchanges designed in part to mitigate credit risk.
	Cash collateral receivable from interest rate swap counterparties represents cash remitted to swap counterparties to meet initial and ongoing margin requirements that are based on the fair value of these Derivatives, including related interest receivable or payable under the terms of the agreements.  The Company may also remit mortgage securities to certain of its swap counterparties to meet ongoing margin requirements.  Such mortgage securities, if any, are included in Residential mortgage investments.  Similarly, Cash collateral payable to interest rate swap counterparties represents cash received from counterparties to meet margin call requirements.  For presentation purposes, the Company does not offset individual counterparty collateral receivables (or payables) with the recorded fair value of related interest rate swap agreements pursuant to master netting arrangements.  In addition, gross unrealized gains on Derivatives (recorded as assets) are stated separately from gross unrealized losses (recorded as liabilities) without regard to counterparty.
	Long-term Incentive Compensation
	Capstead provides its employees and its directors with long-term incentive compensation in the form of equity-based awards.  Equity-based compensation costs are initially measured at the estimated fair value of the awards on the grant date developed using appropriate valuation methodologies, as adjusted for estimates of future award forfeitures.  Valuation methodologies used and subsequent expense recognition is dependent upon each award’s service and performance conditions, the latter also referred to as performance metrics.
	Compensation costs for stock awards subject only to service conditions are measured at the closing stock price on the dates of grant and are recognized as expense on a straight-line basis over the requisite service periods for the awards, as adjusted for changes in estimated, and ultimately actual, forfeitures.  Compensation costs for components of stock awards and restricted stock units (“RSUs”) subject to nonmarket-based performance metrics, (i.e. metrics not predicated on changes in the Company’s stock price) are measured at the closing stock price on the dates of grant, adjusted for the probability of achieving certain benchmarks included in the performance metrics.  These initial cost estimates are recognized as expense over the requisite performance periods, as adjusted for changes in estimated, and ultimately actual, forfeitures and performance.  Compensation costs for components of RSUs subject to market-based performance metrics are measured at the dates of grant using a Monte Carlo simulation model which incorporates into the valuation the inherent uncertainty regarding the achievement of the market-based performance metrics.  These initial valuation amounts are recognized as expense over the requisite performance periods, subject only to adjustments for changes in estimated, and ultimately actual, forfeitures.
	Income Taxes
	Capstead Mortgage Corporation and its qualified REIT subsidiaries (“Capstead REIT”) have elected to be taxed as a REIT.  As a result, Capstead REIT is not taxed on taxable income distributed to stockholders if certain REIT qualification tests are met.  Capstead’s policy is to distribute 100% of the taxable income of the REIT, after application of available tax attributes, within the time limits prescribed by the Internal Revenue Code (the “Code”), which may extend into the subsequent taxable year.  The Company may find it advantageous from time to time to elect taxable REIT subsidiary status for certain of its subsidiaries in which case taxable income of any such subsidiary would be subject to federal and, where applicable, state or local income taxes.  Any such income taxes are accounted for using the liability method.  Related deferred income tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse.
	The Company has not recognized any liabilities for unrecognized tax benefits using a “more likely than not” threshold for the recognition and measurement of the financial statement effects of tax positions taken on a tax return filing.  Should any such liabilities be recognized in future periods, the Company will record related interest and penalties in Other general and administrative expense.
	Dividend Classification
	Capstead records common and preferred stock dividends in the Accumulated deficit component of Stockholders’ equity only to the extent of available earnings for the related period.  Any dividends declared in excess of available earnings are considered a return of capital for financial reporting purposes and are recorded as reductions of Paid-in capital.  The tax and financial reporting classification of dividends can differ primarily as a result of differences between taxable income and Net income and how taxable income is allocated to dividends paid.

NET_INCOME_PER_COMMON_SHARE

NET INCOME PER COMMON SHARE	12 Months Ended
	Dec. 31, 2014
NET INCOME PER COMMON SHARE [Abstract]
NET INCOME PER COMMON SHARE	NOTE 3 ¾ NET INCOME PER COMMON SHARE
	Basic net income per common share is computed by dividing net income, after (a) deducting dividends paid or accrued on preferred stock, (b) deducting any preferred stock redemption premiums paid and (c) allocating earnings to equity awards deemed to be participating securities pursuant to the two-class method, by the weighted average number of shares of common stock outstanding, calculated excluding unvested stock awards.  Participating securities include any unvested equity awards that contain non-forfeitable rights to dividends prior to vesting.
	Diluted net income per common share is computed by dividing the numerator used to compute basic net income per common share after adding back any dividends on shares of convertible preferred stock (prior to their redemption in June 2013 and when such shares were dilutive), by the denominator used to compute basic net income per common share, further adjusted for the dilutive effect, if any, of equity awards and shares of convertible preferred stock.  Shares of the Company’s 7.50% Series E Cumulative Redeemable Preferred Stock first issued in May 2013 are contingently convertible into shares of common stock only upon the occurrence of a change in control and therefore are not considered dilutive securities absent such an occurrence.  Any unvested equity awards that are deemed participating securities are included in the calculation of diluted net income per common share, if dilutive, under either the two-class method or the treasury stock method, depending upon which method produces the more dilutive result.
	Components of the computation of basic and diluted net income per common share were as follows for the indicated periods (dollars in thousands, except per share amounts):
		Year ended December 31
		2014			2013			2012
	Basic net income per common share
	Numerator for basic net income per common share:
	Net income	$	140,820		$	126,487		$	163,626
	Redemption preference premiums paid on Convertible preferred stock		–			(19,924	)		–
	Preferred stock dividends		(13,781	)		(17,536	)		(21,021	)
	Earnings participation of unvested equity awards		(95	)		(139	)		(372	)
		$	126,944		$	88,888		$	142,233
	Denominator for basic net income per common share:
	Weighted average common stock outstanding		95,789			95,679			95,115
	Average unvested stock awards outstanding		(398	)		(506	)		(522	)
			95,391			95,173			94,593
		$	1.33		$	0.93		$	1.5
	Diluted net income per common share
	Numerator for diluted net income per common share:
	Numerator for basic net income per common share	$	126,944		$	88,888		$	142,233
	Dividends on dilutive convertible preferred stock		–			44			298
		$	126,944		$	88,932		$	142,531
	Denominator for diluted net income per common share:
	Denominator for basic net income per common share		95,391			95,173			94,593
	Net effect of dilutive equity awards		238			145			111
	Net effect of dilutive convertible preferred stock		–			75			308
			95,629			95,393			95,012
		$	1.33		$	0.93		$	1.5
	Securities that could be potentially dilutive in the future that were not included in the computation of diluted net income per common share because to do so would have been antidilutive during the indicated periods were as follows (in thousands):
		Year ended December 31
		2014			2013			2012
	Antidilutive convertible preferred stock		–			–			16,493
	Antidilutive equity awards excludable under the treasury stock method:
	Shares issuable under option awards		15			30			10
	RSUs		–			243			–

RESIDENTIAL_MORTGAGE_INVESTMEN

RESIDENTIAL MORTGAGE INVESTMENTS	12 Months Ended
	Dec. 31, 2014
RESIDENTIAL MORTGAGE INVESTMENTS [Abstract]
RESIDENTIAL MORTGAGE INVESTMENTS	NOTE 4 ¾ RESIDENTIAL MORTGAGE INVESTMENTS
	Residential mortgage investments classified by collateral type and interest rate characteristics were as follows as of the indicated dates (dollars in thousands):
			Unpaid		Investment Premiums		Amortized Cost Basis		Carrying		Net			Average
			Principal						Amount (a)		WAC (b)			Yield(b)
			Balance
	31-Dec-14
	Agency Securities:
	Fannie Mae/Freddie Mac:
	Fixed-rate		$	1,660	$	4	$	1,664	$	1,665		6.63	%		6.45	%
	ARMs			10,230,419		328,781		10,559,200		10,800,332		2.51			1.72
	Ginnie Mae ARMs			2,983,659		103,911		3,087,570		3,099,168		2.63			1.53
				13,215,738		432,696		13,648,434		13,901,165		2.54			1.69
	Residential mortgage loans:
	Fixed-rate			1,848		2		1,850		1,850		6.96			5.46
	ARMs			3,046		13		3,059		3,059		3.73			3.14
				4,894		15		4,909		4,909		4.95			3.97
	Collateral for structured financings			1,997		33		2,030		2,030		8.11			7.62
			$	13,222,629	$	432,744	$	13,655,373	$	13,908,104		2.54			1.69
	31-Dec-13
	Agency Securities:
	Fannie Mae/Freddie Mac:
	Fixed-rate		$	2,158	$	6	$	2,164	$	2,167		6.67	%		6.4	%
	ARMs			10,675,620		343,452		11,019,072		11,231,057		2.58			1.59
	Ginnie Mae ARMs			2,145,639		74,396		2,220,035		2,233,495		2.64			1.57
				12,823,417		417,854		13,241,271		13,466,719		2.59			1.59
	Residential mortgage loans:
	Fixed-rate			2,633		3		2,636		2,636		6.99			5.62
	ARMs			4,244		18		4,262		4,262		3.81			3.46
				6,877		21		6,898		6,898		5.03			4.27
	Collateral for structured financings			2,220		37		2,257		2,257		8.09			7.34
			$	12,832,514	$	417,912	$	13,250,426	$	13,475,874		2.59			1.59
	(a)	Includes unrealized gains and losses for residential mortgage investments classified as available-for-sale (see NOTE 9).
	(b)	Net WAC, or weighted average coupon, is the weighted average interest rate of the mortgage loans underlying the indicated investments net of servicing and other fees as of the indicated balance sheet date.  Net WAC is expressed as a percentage calculated on an annualized basis on the unpaid principal balances of the mortgage loans underlying these investments.  Average yield is presented for the year then ended, and is based on the cash component of interest income expressed as a percentage calculated on an annualized basis on average amortized cost basis (the “cash yield”) less the effects of amortizing investment premiums.  Investment premium amortization is determined using the interest method and incorporates actual and anticipated future mortgage prepayments.
	Because of federal government support for the GSEs, Agency Securities are considered to have limited, if any, credit risk.  Residential mortgage loans held by Capstead were originated prior to 1995 when Capstead operated a mortgage conduit and the related credit risk is borne by the Company.  Collateral for structured financings consists of private residential mortgage securities that are backed by loans obtained through this mortgage conduit and are pledged to secure repayment of related structured financings.  Credit risk for these securities is borne by the related bondholders.  The maturity of Residential mortgage investments is directly affected by prepayments of principal on the underlying mortgage loans.  Consequently, actual maturities will be significantly shorter than the portfolio’s weighted average contractual maturity of 290 months.
	Fixed-rate investments consist of residential mortgage loans and Agency Securities backed by residential mortgage loans with fixed rates of interest.  Adjustable-rate investments generally are ARM Agency Securities backed by residential mortgage loans that have coupon interest rates that adjust at least annually to more current interest rates or begin doing so after an initial fixed-rate period.  After the initial fixed-rate period, if applicable, mortgage loans underlying ARM securities typically either (i) adjust annually based on specified margins over the one-year Constant Maturity U.S. Treasury Note Rate (“CMT”) or the one-year London interbank offered rate (“LIBOR”), (ii) adjust semiannually based on specified margins over six-month LIBOR, or (iii) adjust monthly based on specified margins over indices such as one-month LIBOR, the Eleventh District Federal Reserve Bank Cost of Funds Index, or over a rolling twelve month average of the one-year CMT index, usually subject to periodic and lifetime limits, or caps, on the amount of such adjustments during any single interest rate adjustment period and over the contractual term of the underlying loans.
	Capstead classifies its ARM securities based on each security’s average number of months until coupon reset (“months to roll”).  Months to roll is an indicator of asset duration which is a measure of market price sensitivity to interest rate movements.  A shorter duration generally indicates less interest rate risk.  Current-reset ARM securities have months to roll of less than 18 months while longer-to-reset ARM securities have months to roll of 18 months or greater.  As of December 31, 2014, the average months to roll for the Company’s $7.67 billion (amortized cost basis) in current-reset ARM securities was 6.4 months while the average months to roll for the Company’s $5.98 billion (amortized cost basis) in longer-to-reset ARM securities was 39.5 months.

INVESTMENTS_IN_UNCONSOLIDATED_

INVESTMENTS IN UNCONSOLIDATED AFFILIATES	12 Months Ended
	Dec. 31, 2014
INVESTMENTS IN UNCONSOLIDATED AFFILIATES [Abstract]
INVESTMENTS IN UNCONSOLIDATED AFFILIATES	NOTE 5 ¾ INVESTMENTS IN UNCONSOLIDATED AFFILIATES
	To facilitate the issuance of Unsecured borrowings, in 2006 and 2005 Capstead formed and capitalized three Delaware statutory trusts through the issuance to the Company of the trusts’ common securities totaling $3.1 million (see NOTE 8).  In December 2013 the Company simplified its capital structure by dissolving the trusts and distributing the related junior subordinated notes (originally issued to the trusts by the Company) to the holders of the trusts’ common and preferred securities.  Prior to dissolution, the Company’s equity in the earnings of the trusts consisted solely of the common trust securities’ pro rata share in interest accruing on junior subordinated notes issued to the trusts.

REPURCHASE_ARRANGEMENTS_AND_SI

REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS	12 Months Ended
	Dec. 31, 2014
REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS [Abstract]
REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS	NOTE 6 ¾ REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS
	Capstead pledges its Residential mortgage investments as collateral under repurchase arrangements with commercial banks and other financial institutions, referred to as counterparties, the terms and conditions of which are negotiated on a transaction-by-transaction basis when each such borrowing is initiated or renewed.  Repurchase arrangements entered into by the Company involve the sale and a simultaneous agreement to repurchase the transferred assets at a future date and are accounted for as borrowings.  The Company maintains the beneficial interest in the specific securities pledged during the term of each repurchase arrangement and receives the related principal and interest payments.  The amount borrowed is generally equal to the fair value of the securities pledged, as determined by the lending counterparty, less an agreed-upon discount, referred to as a “haircut.”  Interest rates on these borrowings are fixed based on prevailing rates corresponding to the terms of the borrowings, and interest is paid at the termination of the repurchase arrangement at which time the Company may enter into a new repurchase arrangement at prevailing haircuts and rates with the same counterparty or repay that counterparty and negotiate financing with a different counterparty.  None of the Company’s counterparties are obligated to renew or otherwise enter into new repurchase arrangements at the conclusion of existing repurchase arrangements. In response to declines in fair value of pledged securities due to changes in market conditions or the publishing of monthly security pay down factors, lenders typically require the Company to post additional securities as collateral, pay down borrowings or fund cash margin accounts with the counterparties in order to re-establish the agreed-upon collateral requirements.  These actions are referred to as margin calls.  Conversely, in response to increases in fair value of pledged securities, the Company routinely margin calls its lending counterparties in order to return previously pledged collateral.
	Repurchase arrangements and similar borrowings (and related pledged collateral, including accrued interest receivable), classified by collateral type and remaining maturities, and related weighted average borrowing rates as of the indicated dates were as follows (dollars in thousands):
	Collateral Type		Collateral		Accrued			Borrowings		Average
			Carrying		Interest			Outstanding		Borrowing
			Amount		Receivable					Rates
	31-Dec-14
	Borrowings with maturities of 30 days or less:
	Agency Securities		$	10,401,080	$	24,045		$	9,878,889		0.35	%
	Borrowings with maturities greater than 30 days:
	Agency Securities (31 to 90 days)			1,205,570		2,248			1,150,924		0.35
	Agency Securities (greater than 90 days)			1,874,892		4,640			1,775,000		0.56
	Similar borrowings:
	Collateral for structured financings*			2,030		–			2,030		8.11
			$	13,483,572	$	30,933		$	12,806,843		0.38
	Year-end borrowing rates adjusted for effects of related Derivatives (see NOTE 7)										0.58
	31-Dec-13
	Borrowings with maturities of 30 days or less:
	Agency Securities		$	12,169,534	$	28,195		$	11,578,211		0.38	%
	Borrowings with maturities greater than 30 days:
	Agency Securities (31 to 90 days)			951,966		2,068			902,432		0.38
	Similar borrowings:
	Collateral for structured financings*			2,257		–			2,257		8.09
			$	13,123,757	$	30,263		$	12,482,900		0.38
	Year-end borrowing rates adjusted for effects of related Derivatives held as cash flow hedges										0.49
	*	The maturity of structured financings is directly affected by prepayments on the related mortgage pass-through securities pledged as collateral.  Additionally, these financings are subject to redemption by the residual bondholders.
	Average borrowings outstanding differed from respective year-end balances during the indicated periods primarily due to changes in portfolio levels and differences in the timing of portfolio acquisitions relative to portfolio runoff as illustrated below (dollars in thousands):
			Year ended December 31
			2014					2013
			Average		Average			Average		Average
			Borrowings		Rate			Borrowings		Rate
	Average borrowings and rates adjusted for the effects of related Derivatives held as cash flow hedges for the indicated years		$	12,651,061		0.52	%	$	12,702,941		0.52	%
	Interest paid on Repurchase arrangements and similar borrowings, including related Derivative cash flows, totaled $59.7 million, $71.1 million and $69.5 million during 2014, 2013 and 2012, respectively.

USE_OF_DERIVATIVE_FINANCIAL_IN

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT	12 Months Ended
	Dec. 31, 2014
USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT [Abstract]
USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT	NOTE 7 ¾ USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT
	To help mitigate exposure to higher interest rates, Capstead typically uses currently-paying and forward-starting, one-month LIBOR-indexed, pay-fixed, receive-variable, interest rate swap agreements that require interest payments for two-year terms.  These Derivatives are designated as cash flow hedges of the variability of the underlying benchmark interest rate of current and forecasted 30- to 90-day borrowings under repurchase arrangements.  This hedge relationship establishes a relatively stable fixed rate on related borrowings because the variable-rate payments received on the swap agreements offset a significant portion of the interest accruing on the related borrowings, leaving the fixed-rate swap payments as the Company’s effective borrowing rate, subject to certain adjustments.  These adjustments include differences between variable rate payments received on the swap agreements and related unhedged borrowing rates as well as the effects of measured hedge ineffectiveness.  Additionally, changes in fair value of these Derivatives tend to partially offset opposing changes in fair value of the Company’s residential mortgage investments that can occur in response to changes in market interest rates.
	During 2014 Capstead entered into swap agreements with notional amounts of $2.30 billion.  These swap agreements require fixed rate interest payments averaging 0.62% for two-year periods commencing on various dates between April 2014 and January 2015.  Also during 2014, $1.30 billion notional amount of swaps requiring fixed rate interest payments averaging 0.55% matured, while $4.30 billion notional amount of forward-starting swaps requiring fixed rate interest payments averaging 0.54% moved into current-pay status.
	At December 31, 2014, the Company’s portfolio of financing-related swap positions had the following characteristics (dollars in thousands):
	Period of		Notional				Average Fixed Rate
	Contract Expiration		Amount				Payment Requirement
	Currently-paying contracts:
	First quarter 2015		$	1,100,000				0.5	%
	Second quarter 2015			200,000				0.43
	Third quarter 2015			400,000				0.47
	Fourth quarter 2015			1,200,000				0.45
	First quarter 2016			1,700,000				0.51
	Second quarter 2016			1,100,000				0.47
	Third quarter 2016			700,000				0.56
	Fourth quarter 2016			800,000				0.66
	(average expiration: 12 months)			7,200,000				0.51
	Forward-starting contracts:
	First quarter 2017 (average expiration: 24 months)			500,000				0.72
	(average expiration: 12 months)		$	7,700,000
	In addition to portfolio financing-related swap positions, in 2010 the Company entered into three forward-starting, three-month LIBOR-indexed, pay-fixed, receive-variable, interest rate swap agreements with notional amounts totaling $100 million and average fixed rates of 4.09% with 20-year payment terms coinciding with the floating-rate terms of the Company’s Unsecured borrowings which begin between October 30, 2015 and September 15, 2016.  These Derivatives are designated as cash flow hedges of the variability of the underlying benchmark interest rate associated with the floating-rate terms of these long-term borrowings (see NOTE 8).
	Interest rate swap agreements are measured at fair value on a recurring basis primarily using Level Two Inputs in accordance with ASU 2010-06, Fair Value Measurements and Disclosures (Topic 820).  In determining fair value estimates for these Derivatives, Capstead utilizes the standard methodology of netting the discounted future fixed cash payments and the discounted future variable cash receipts which are based on expected future interest rates derived from observable market interest rate curves.  Related net interest payable at the balance sheet date is recorded separately.  The Company also incorporates both its own nonperformance risk and its counterparties’ nonperformance risk in determining the fair value of these Derivatives.  In considering the effect of nonperformance risk, the Company considered the impact of netting and credit enhancements, such as collateral postings and guarantees, and has concluded that counterparty risk is not significant to the overall valuation of these agreements.
	The following tables include fair value and other related disclosures regarding all Derivatives held as of and for the indicated periods (in thousands):
		Balance Sheet		31-Dec
		Location		2014				2013
	Balance sheet-related
	Swap agreements in a gain position (an asset) related to:
	Borrowings under repurchase arrangements	(a)		$	1,657			$	1,094
	Unsecured borrowings	(a)			–				3,911
	Swap agreements in a loss position (a liability) related to:
	Borrowings under repurchase arrangements	(a)			(6,332	)			(11,304	)
	Unsecured borrowings	(a)			(20,702	)			–
	Related net interest payable	(b)			(9,516	)			(5,493	)
				$	(34,893	)		$	(11,792	)
	(a)	The fair value of Derivatives with realized and unrealized gains are aggregated and recorded as an asset on the face of the Balance Sheets separately from the fair value of Derivatives with realized and unrealized losses that are recorded as a liability.  The amount of unrealized losses scheduled to be recognized in the Statements of Income over the next twelve months primarily in the form of fixed-rate swap payments in excess of current market rates totaled $12.2 million at December 31, 2014.
	(b)	Included in “Accounts payable and accrued expenses” on the face of the Balance Sheets.
			Location of Gain or (Loss) Recognized in				Year ended December 31
			Net Income				2014				2013			2012
	Income statement-related
	Components of effect on interest expense:
	Amount of loss reclassified from Accumulated other comprehensive income related to the effective portion of active positions						$	(22,055	)		$	(16,914	)	$	(19,882	)
	Amount of gain (loss) recognized (ineffective portion)							(473	)			24			(542	)
	Increase in interest expense and decrease in Net income as a result of the use of Derivatives			*			$	(22,528	)		$	(16,890	)	$	(20,424	)
	Other comprehensive income-related
	Amount of gain (loss) recognized in Other comprehensive income (loss) (effective portion)						$	(41,059	)		$	9,320		$	(22,262	)
		*	Included in “Interest expense:  Repurchase arrangements and similar borrowings” on the face of the Statements of Income.
	Capstead’s swap agreements and borrowings under repurchase arrangements are subject to master netting arrangements in the event of default on, or termination of, any one contract.  See NOTE 6 for more information on the Company’s use of repurchase arrangements.  The following tables provide disclosures concerning offsetting of financial liabilities and Derivatives as of the indicated dates (in thousands):
			Offsetting of Derivative Asset
			Gross				Gross				Net Amounts			Gross Amounts Not Offset
							Amounts				of Assets			in the Balance Sheet(a)
			Amounts of				Offset in				Presented in			Financial Instruments			Cash Collateral Received			Net
			Recognized				the Balance				the Balance									Amount
			Assets				Sheet				Sheet
	31-Dec-14
	Counterparty 2		$	–			$	95			$	95		$	(95	)	$	–		$	–
	Counterparty 4			1,128				434				1,562			(1,562	)		–			–
			$	1,128			$	529			$	1,657		$	(1,657	)	$	–		$	–
	31-Dec-13
	Counterparty 1		$	3,911			$	–			$	3,911		$	(3,911	)	$	–		$	–
	Counterparty 2			634				–				634			(634	)		–			–
	Counterparty 4			460				–				460			(460	)		–			–
			$	5,005			$	–			$	5,005		$	(5,005	)	$	–		$	–
			Offsetting of Financial Liabilities and Derivative Liabilities
			Gross				Gross				Net Amounts			Gross Amounts Not Offset
							Amounts				of Liabilities			in the Balance Sheet (c)
		Amounts of				Offset in				Presented in			Financial			Cash			Net
		Recognized				the Balance				the Balance			Instruments			Collateral			Amount
		Liabilities(b)				Sheet				Sheet (a)						Pledged
31-Dec-14
Derivatives by counterparty:
Counterparty 1		$	24,533			$	–			$	24,533		$	–		$	(24,533	)	$	–
Counterparty 2			4,042				95				4,137			(95	)		(4,042	)		–
Counterparty 3			736				–				736			–			(736	)		–
Counterparty 4			6,710				434				7,144			(1,562	)		(5,582	)		–
			36,021				529				36,550			(1,657	)		(34,893	)		–
Repurchase arrangements and similar borrowings			12,812,947				–				12,812,947			(12,812,947	)		–			–
		$	12,848,968			$	529			$	12,849,497		$	(12,814,604	)	$	(34,893	)	$	–
31-Dec-13
Derivatives by counterparty:
Counterparty 1		$	6,002			$	–			$	6,002		$	(3,911	)	$	(2,091	)	$	–
Counterparty 2			6,352				–				6,352			(634	)		(5,718	)		–
Counterparty 3			1,581				–				1,581			–			(1,581	)		–
Counterparty 4			2,862				–				2,862			(460	)		(2,402	)		–
			16,797				–				16,797			(5,005	)		(11,792	)		–
Repurchase arrangements and similar borrowings			12,487,604				–				12,487,604			(12,487,604	)		–			–
		$	12,504,401			$	–			$	12,504,401		$	(12,492,609	)	$	(11,792	)	$	–
(a)	Amounts presented are limited to recognized liabilities and cash collateral received associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.
(b)	Amounts include accrued interest of $9.5 million and $5.5 million on interest rate swap agreements and $6.1 million and $4.7 million on repurchase arrangements and similar borrowings, included in “Accounts payable and accrued expenses” on the face of the Balance Sheets as of December 31, 2014 and December 31, 2013, respectively.
(c)	Amounts presented are limited to recognized assets and collateral pledged associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.
Changes in Accumulated other comprehensive income by component for the three years ended December 31, 2014 were as follows (in thousands):
		Gains and Losses				Unrealized Gains				Total
		on Cash Flow				and Losses on
		Hedges				Available-for-Sale
						Securities
Balance at December 31, 2011		$	(30,159	)		$	234,699			$	204,540
Activity for the year ended December 31, 2012:
Other comprehensive income (loss) before reclassifications			(22,262	)			91,750				69,488
Amounts reclassified from accumulated other comprehensive income			19,882				–				19,882
Other comprehensive income (loss)			(2,380	)			91,750				89,370
Balance at December 31, 2012			(32,539	)			326,449				293,910
Activity for the year ended December 31, 2013:
Other comprehensive income (loss) before reclassifications			9,320				(101,001	)			(91,681	)
Amounts reclassified from accumulated other comprehensive income			16,914				–				16,914
Other comprehensive income (loss)			26,234				(101,001	)			(74,767	)
Balance at December 31, 2013			(6,305	)			225,448				219,143
Activity for the year ended December 31, 2014:
Other comprehensive income (loss) before reclassifications			(41,059	)			27,283				(13,776	)
Amounts reclassified from accumulated other comprehensive income			22,055				–				22,055
Other comprehensive income (loss)			(19,004	)			27,283				8,279
Balance at December 31, 2014		$	(25,309	)		$	252,731			$	227,422

UNSECURED_BORROWINGS

UNSECURED BORROWINGS	12 Months Ended
	Dec. 31, 2014
UNSECURED BORROWINGS [Abstract]
UNSECURED BORROWINGS	NOTE 8 ¾ UNSECURED BORROWINGS
	Unsecured borrowings consist of 30-year junior subordinated notes originally issued in 2005 and 2006 to three special-purpose statutory trusts formed to issue $3.1 million of the trusts’ common securities to Capstead and to privately place $100 million of so-called trust preferred securities with unrelated third party investors.  In December 2013 the statutory trusts were dissolved after the subordinated notes were distributed to the holders of the trusts’ common and preferred securities.  Included in Receivables and other assets are $2.1 million in remaining issue costs at December 31, 2014 associated with the original issuance of these notes.  Note balances and related weighted average interest rates as of the indicated dates (calculated including issue cost amortization) were as follows (dollars in thousands):
			31-Dec-14					31-Dec-13
			Borrowings		Average			Borrowings		Average
			Outstanding		Rate *			Outstanding		Rate *
	Junior subordinated notes associated with:
	Capstead Mortgage Trust I		$	35,000		8.31	%	$	35,000		8.31	%
	Capstead Mortgage Trust II			40,000		8.46			40,000		8.46
	Capstead Mortgage Trust III			25,000		8.78			25,000		8.78
			$	100,000		8.49		$	100,000		8.49
	*	The indicated weighted average rates have been in effect since issuance.  After considering cash flow hedges that coincide with the floating rate terms of these borrowings that begin October 30, and December 15, 2015 for the notes associated with Capstead Mortgage Trusts I and II and September 15, 2016 for the notes associated with Capstead Mortgage Trust III, the effective borrowing rate will average 7.56% beginning September 15, 2016 through maturity, subject to certain adjustments for the effects of measured hedge ineffectiveness, if any.
	The notes associated with Capstead Mortgage Trust I mature in October 2035 and are currently redeemable, in whole or in part, without penalty, at the Company’s option.  The notes associated with Capstead Mortgage Trust II mature in December 2035 and are redeemable, in whole or in part, without penalty, at the Company’s option anytime on or after December 15, 2015.  The notes associated with Capstead Mortgage Trust III mature in September 2036 and are redeemable, in whole or in part, without penalty, at the Company’s option anytime on or after September 15, 2016.
	Since issuance, the weighted average effective interest rate for Unsecured borrowings (calculated including issue cost amortization) was 8.49% and related interest paid was $8.4 million, $8.6 million, and $8.6 million during 2014, 2013 and 2012, respectively.

DISCLOSURES_REGARDING_FAIR_VAL

DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2014
DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS [Abstract]
DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS	NOTE 9 ¾ DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS
	This note provides fair value-related disclosures as of the indicated balance sheet dates for Capstead’s financial assets and liabilities, most of which are influenced by changes in, and market expectations for changes in, interest rates and market liquidity conditions, as well as other factors beyond the control of management.  All fair values were determined using Level 2 Inputs in accordance with ASU 2010-06, Fair Value Measurements and Disclosures (Topic 820).
	Residential mortgage investments, nearly all of which are mortgage securities classified as available-for-sale, are measured at fair value on a recurring basis.  In determining fair value estimates for mortgage securities, the Company considers recent trading activity for similar investments and pricing levels indicated by lenders in connection with designating collateral for repurchase arrangements, provided such pricing levels are considered indicative of actual market clearing transactions.  In determining fair value estimates for longer-term borrowings under repurchase arrangements, the Company considers pricing levels indicated by lenders for entering into new transactions using similar pledged collateral with terms equal to the remaining terms of the longer-term borrowings.  In determining fair value estimates for unsecured borrowings, the Company considers current pricing for financial instruments with similar characteristics.  Excluded from these disclosures are financial instruments for which the Company’s cost basis is deemed to approximate fair value due primarily to the short duration of these instruments, which are valued using primarily Level 1 measurements, including Cash and cash equivalents, cash collateral receivable from, or payable to, interest rate swap counterparties, receivables, payables and borrowings under repurchase arrangements with initial terms of 120 days or less.  See NOTE 7 for information relative to the valuation of interest rate swap agreements.
	Fair value-related disclosures for financial instruments other than debt securities were as follows as of the indicated dates (in thousands):
		31-Dec-14				31-Dec-13
		Carrying		Fair		Carrying		Fair
		Amount		Value		Amount		Value
	Financial assets:
	Residential mortgage loans	$	4,909	$	5,000	$	6,898	$	7,000
	Interest rate swap agreements		1,657		1,657		5,005		5,005
	Financial liabilities:
	Repurchase arrangements with initial terms of greater than 120 days		2,128,517		2,128,400		36,299		36,300
	Unsecured borrowings		100,000		100,500		100,000		101,000
	Interest rate swap agreements		27,034		27,034		11,304		11,304
	Fair value-related disclosures for debt securities were as follows as of the indicated dates (in thousands):
		Amortized		Gross Unrealized
		Cost Basis		Gains		Losses		Fair Value
	31-Dec-14
	Agency Securities classified as available-for-sale:
	Fannie Mae/Freddie Mac	$	10,559,231	$	243,351	$	2,218	$	10,800,364
	Ginnie Mae		3,087,570		16,755		5,157		3,099,168
	Residential mortgage securities classified as held-to-maturity		3,663		124		–		3,787
	31-Dec-13
	Agency Securities classified as available-for-sale:
	Fannie Mae/Freddie Mac		11,019,116		224,456		12,468		11,231,104
	Ginnie Mae		2,220,035		18,384		4,924		2,233,495
	Residential mortgage securities classified as held-to-maturity		4,376		211		–		4,587
		31-Dec-14				31-Dec-13
		Fair		Unrealized		Fair		Unrealized
		Value		Loss		Value		Loss
	Securities in an unrealized loss position:
	One year or greater	$	706,839	$	5,320	$	39,030	$	380
	Less than one year		1,095,724		2,055		2,857,724		17,012
		$	1,802,563	$	7,375	$	2,896,754	$	17,392
	Capstead’s investment strategy involves managing a leveraged portfolio of relatively short-duration ARM Agency Securities and management expects these securities will be held until payoff absent a major shift in strategy or a severe contraction in the Company’s ability to obtain financing to support its portfolio.  Declines in fair value caused by increases in interest rates are typically modest for investments in short-duration ARM Agency Securities compared to investments in longer-duration ARM or fixed-rate assets.  These declines are generally recoverable in a relatively short period of time as coupon interest rates on the underlying mortgage loans reset to rates more reflective of the then current interest rate environment.
	From a credit risk perspective, federal government support for the GSEs helps ensure that fluctuations in value due to credit risk associated with these securities will be limited.  Given that (a) any existing unrealized losses on mortgage securities held by the Company are not attributable to credit risk and declines in fair value of ARM securities due to changes in interest rates are generally recoverable in a relatively short period of time, (b) the Company typically holds its investments to maturity, and (c) it is more likely than not that the Company will not be required to sell any of its investments given the resiliency of the financing market for Agency Securities, none of these investments are considered other-than-temporarily impaired at December 31, 2014.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
INCOME TAXES [Abstract]
INCOME TAXES	NOTE 10 ¾ INCOME TAXES
	Capstead REIT and a subsidiary for which the Company has elected taxable REIT subsidiary status file separate tax returns in U.S. federal and state jurisdictions, where applicable.  Provided Capstead REIT remains qualified as a REIT and all its taxable income is distributed to stockholders within allowable time limits, no income taxes are due on this income.  Accordingly, no provision has been made for income taxes for Capstead REIT.  Taxable income, if any, of the Company’s taxable REIT subsidiary, which is largely dormant, is fully taxable and provision is made for any resulting income taxes.  The Company is no longer subject to examination and the related assessment of tax by federal, state, or local tax authorities for years before 2011, with the possible exception of certain information reporting and disclosure penalties with respect to earlier years.  Management believes any such amounts would not have a material adverse effect on the Company’s financial condition.
	The Company’s effective tax rate differs substantially from statutory federal income tax rates primarily due to the benefit of Capstead REIT’s status as a REIT, along with other items affecting the Company’s effective tax rate as illustrated below for the indicated periods (in thousands):
			Year ended December 31
			2014			2013			2012
	Income taxes computed at the federal statutory rate		$	49,287		$	44,270		$	57,269
	Benefit of REIT status			(49,28	)		(44,270	)		(57,268	)
	Income taxes computed on income of Capstead’s sole taxable REIT subsidiary			4			–			1
	Change in net deferred income tax assets			(4	)		1			(1	)
	Other			–			(1	)		–
	Income tax provision		$	–		$	–		$	–
	No income taxes were paid during 2014, 2013 or 2012.  Significant components of the Company’s taxable REIT subsidiary’s deferred income tax assets and liabilities were as follows as of the indicated dates (in thousands):
			31-Dec
			2014			2013
	Deferred income tax assets:
	Alternative minimum tax credit (a)		$	1,941		$	1,942
	Net operating loss carryforwards (b)			58			60
	Other			20			21
				2,019			2,023
	Deferred income tax liabilities			–			–
	Net deferred tax assets		$	2,019		$	2,023
	Valuation allowance (c)		$	2,019		$	2,023
		(a)	Alternative minimum tax credit carryforwards can be utilized to offset payment of federal income taxes on future taxable income, if any, earned by this subsidiary, subject to certain limitations.
		(b)	Excludes $3.5 million in remaining net operating loss carryforwards which expire beginning after 2019.  To the extent these carryforwards are utilized in future periods, the benefit will reduce actual taxes payable.
		(c)	Because this subsidiary is not expected to earn significant amounts of taxable income, related net deferred tax assets are fully reserved at December 31, 2014.

STOCKHOLDERS_EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2014
STOCKHOLDERS EQUITY [Abstract]
STOCKHOLDERS' EQUITY	NOTE 11 ¾ STOCKHOLDERS’ EQUITY
	In May 2013 Capstead completed a public offering of 6.8 million shares ($170.0 million face amount) of its 7.50% Series E Cumulative Redeemable Preferred Stock, liquidation preference $25.00 per share.  Shares of the Series E preferred stock are redeemable at the Company’s option for $25.00 per share, plus any accumulated and unpaid dividends, on or after May 13, 2018.  Proceeds of the offering after underwriting fees and other costs totaled $164.3 million and together with $42.7 million of cash on hand were used to fund the June 2013 redemption of the Company’s then-outstanding convertible preferred stock.  The shares of the convertible preferred stock that were redeemed had redemption preferences aggregating $207.0 million, a total of $19.9 million in excess of these shares’ recorded amounts on the balance sheet.  This redemption preference premium is reflected as a $0.21 per common share reduction in net income available to common stockholders for the year ended December 31, 2013.
	In late 2013 Capstead began issuing additional shares of Series E preferred stock through an at-the-market continuous offering program.  Shares of Series E preferred stock issued under this program, issue prices and proceeds, both presented net of underwriting fees and other costs were as follows for the indicated periods:
		Shares		Net		Net
				Issue Price		Proceeds
	Year ended December 31, 2013		61,000	$	23.78	$	1,447,000
	Year ended December 31, 2014		757,000		24.01		18,180,000
	Subsequent to year-end through February 27, 2015 (unaudited)		222,000		24.65		5,465,000
	During 2012 the Company raised $142.0 million in new common equity capital, after underwriting discounts and offering expenses, by issuing 10.5 million shares of common stock through a similar program.  Also during 2012, the Company raised $4.5 million, net of expenses, in convertible preferred equity capital by issuing 309,000 shares of convertible preferred stock through a similar program.
	Additional amounts of Series E preferred capital and new common equity capital may be raised in the future under continuous offering programs or by other means, subject to market conditions, compliance with federal securities laws and blackout periods associated with the dissemination of earnings and dividend announcements and other important Company-specific news.
	Between November 2012 and January 2013, the Company repurchased 3.6 million shares of common stock at a cost of $42.4 million pursuant to a $100 million common stock repurchase program.
	During 2014, 2013 and 2012, additions to common equity capital related to equity-based awards to directors and employees totaled $1.9 million, $1.8 million and $4.4 million, respectively, consisting primarily of amounts related to stock awards and also including net proceeds from the exercise of option awards.  See NOTE 12 for further information pertaining to long-term equity-based awards.
	Capstead’s charter provides that if its board of directors determines in good faith that the direct or indirect ownership of the common shares has become concentrated to an extent which would cause Capstead REIT to fail to qualify as a REIT, the Company may redeem or repurchase, at fair market value, any number of shares of common or preferred stock sufficient to maintain or bring such ownership into conformity with the Code.  In addition, the Company may refuse to transfer or issue shares of common or preferred stock to any person whose ownership of such shares would result in Capstead REIT being unable to comply with the requirements of the Code.  Finally, the charter provides that the Company may redeem or refuse to transfer any of its shares to prevent the imposition of a penalty tax as a result of ownership of such shares by certain disqualified organizations, including governmental bodies and tax-exempt entities that are not subject to tax on unrelated business taxable income.

COMPENSATION_PROGRAMS

COMPENSATION PROGRAMS	12 Months Ended
	Dec. 31, 2014
COMPENSATION PROGRAMS [Abstract]
COMPENSATION PROGRAMS	NOTE 12 ¾ COMPENSATION PROGRAMS
	The compensation committee of Capstead’s board of directors (the “Committee”) administers all compensation programs for employees including salaries, short- and long-term incentive compensation, including equity-based awards, as well as other benefit programs.  After reviewing existing programs and practices and soliciting feedback from investors during 2013, the Committee made a number of important changes that became effective in 2013 and early 2014.  The most prominent changes involved replacing an absolute return-based, discretionary bonus program and an absolute return-based stock award program with largely nondiscretionary and formulaic, target-based annual and long-term incentive compensation programs for key executives with multiple, pre-established performance goals and defined threshold, target and maximum awards as a percentage of base salary.
	In May 2014 stockholders approved the Amended and Restated 2014 Flexible Incentive Plan, which provides for the issuance of up to five million shares of common stock pursuant to equity-based awards as well as other incentive awards that recognize the creation of value for stockholders and promote the Company’s long-term growth and success.  At December 31, 2014, the Plan had 4,927,763 shares of common stock remaining available for future issuances.
	Short-Term Incentive Compensation Programs
	Effective June 30, 2013, the Committee terminated the absolute return-based, discretionary bonus program and adopted the new annual incentive compensation program that included relative performance metrics measured against the Company’s peers in the mortgage REIT industry as well as the attainment of individual goals and objectives for key executives.  The relative performance metrics used were based on relative economic return (change in book value plus dividends) and relative operating efficiency (operating expenses divided by Unsecured borrowings and Stockholders’ equity), calculated for the full year and prorated for the six month period during which the program was effective in 2013.
	Under this new program, each performance metric is assigned a weighting and the Company’s performance relative to each metric is calculated separately. No awards can be earned for performance below the defined threshold returns and awards are capped for performance above the defined maximum return levels.  For 2014 the program was modified to add an absolute economic return performance metric which measures performance against defined return levels.  Included in Accounts payable and accrued expenses at December 31, 2014 are annual incentive compensation accruals for all employees totaling $1.4 million.  Recognized in Short-term incentive compensation are $1.2 million, $2.8 million and $4.1 million related to annual incentive compensation for all employees during 2014, 2013 and 2012, respectively.
	The Committee administers an additional performance-based short-term incentive compensation program for key executives that provides for quarterly cash payments equal to per share dividends declared on Capstead’s common stock multiplied by a notional amount of non-vesting or “phantom” shares of common stock (“Dividend Equivalent Rights” or “DERs”).  DERs only represent the right to receive the same cash distributions that the Company’s common stockholders are entitled to receive during the term of the grants, subject to certain conditions, including continuous service.  In December 2014 the Committee extended the term of the 654,000 outstanding DERs to December 31, 2015.  Included in Accounts payable and accrued expenses are fourth quarter 2014 DERs distribution amounts totaling $222,000 that were paid in January 2015.  Recognized in Short-term incentive compensation are $889,000, $811,000 and $914,000 related to the DERs program during 2014, 2013 and 2012, respectively.
	Long-term Equity-based Awards – Performance-based RSUs
	The Committee adopted the new performance-based long-term incentive compensation program for key executives in December 2013.  The program provides for the grant of performance-based RSUs that are convertible into common shares following three-year performance periods, contingent upon whether, and to what extent, defined performance levels established for certain relative and absolute return performance metrics are met or exceeded.  The relative return metrics measure the Company’s performance against its peers in the mortgage REIT industry on the basis of relative economic return and relative total stockholder return (change in stock price plus reinvested dividends).  The absolute economic return metric measures performance against defined return levels.  For conversion purposes, each performance metric is assigned a weighting and the Company’s performance relative to each metric is calculated separately.  The actual number of shares of common stock the units can convert into for each of the metrics, if any, can range from one-half of a share per unit if that metric’s minimum threshold of performance is met, to two shares per unit if the related maximum performance threshold is met or exceeded, adjusted for the weighting assigned to the metric.  If a metric’s minimum performance threshold is not met, no shares are issuable under that metric.  Dividends accrue from the date of grant and will be paid in cash when the units convert into shares of common stock based on the number of shares ultimately issued, if any.
	Pursuant to this program, in January 2015 and December 2013 the Committee granted 247,512 and 242,505 RSUs with three-year performance periods ending December 31, 2017 and 2016, respectively.  Initial grant date fair values of $8.83 and $12.45 were assigned to each unit of the January 2015 and December 2013 grants, respectively.  These initial fair values imply compensation costs of $2.2 million and $3.0 million, respectively, to be recognized as expense over the three-year performance periods assuming performance levels estimated at issuance are achieved and there are no forfeitures.  During 2014 the three-year compensation cost estimate for the December 2013 grant was reduced to $1.7 million, or $7.21 per unit, due to lowered expectations for attainment of certain nonmarket-based performance metrics and recognized in Long-term incentive compensation is $582,000 related to the first year of this grant’s three-year performance period.  Included in Common Stock dividends payable at December 31, 2014 and 2013 are estimated dividends payable pertaining to these awards of $213,000 and $75,000, respectively.
	Long-term Equity-based Awards – Stock Awards
	Under an absolute return performance-based stock award program terminated in 2013, the Committee granted common stock awards to all employees with staggered three-year vesting periods.  These awards vest if annualized returns in excess of established return levels are generated during three-year measurement periods.  Vesting can be deferred and a new three-year measurement period established to include the subsequent year, up to and including the seventh calendar year after the year of grant.  Any remaining unvested awards issued under this program will expire if the required returns are not generated for the final three-year measurement period.  Grants under this program for 114,423, 121,026 and 67,599 shares vested during 2014, 2013 and 2012, respectively.  Average grant date fair values for these grants were $13.31, $12.01 and $10.18, respectively.  Grants for another 125,221 shares with an average grant date fair value of $12.58 vested in February 2015 pertaining to initial measurement periods ending December 31, 2014.  Grants for 133,571 and 69,849 shares with average grant date fair values of $12.17 and $11.67 will vest in January of 2016 and 2017, respectively, if annualized returns in excess of established return levels are generated during these grants’ initial measurement periods.
	In December 2014 and 2013 respectively, the Committee granted service-based stock awards for 37,237 and 35,703 shares of common stock with grant date fair values of $12.47 and $12.34 to employees that weren’t awarded RSUs.  These awards vest January 2, 2018 and January 2, 2017, respectively.  In January 2014 the remaining 22,164 shares associated with 2007 service-based stock awards issued to all employees vested.  As a component of the Company’s director compensation program, directors are granted stock awards annually upon election or re-election to the board of directors that vest approximately one year from issuance.  In July 2014, director stock awards for 35,000 shares with a grant date fair value of $13.16 were granted that vest in July 2015.  In April 2014, director grants awarded in 2013 for 28,000 shares with a grant date fair value of $13.02 vested.
	Performance-based and service-based stock award activity for year ended December 31, 2014 is summarized below:
		Number of			Weighted Average
		Shares			Grant Date
					Fair Value
	Unvested stock awards outstanding at beginning of year		528,931		$	12.51
	Grants		72,237			12.8
	Vestings		(164,587	)		13.23
	Unvested stock awards outstanding at end of year		436,581			12.29
	During 2014, 2013 and 2012, the Company recognized in Long-term incentive compensation $1.5 million, $1.8 million and $1.9 million, respectively, related to amortization of the grant date fair value of employee performance-based and service-based stock awards.  The amounts amortized for these periods assumed that performance metrics, if applicable, would continue to be met for related initial measurement periods.  In addition, the Company recognized in Other general and administrative expense $315,000, $387,000 and $362,000 related to amortization of the grant date fair value of service-based director stock awards during 2014, 2013 and 2012, respectively.  Unrecognized compensation expense for unvested stock awards totaled $2.2 million as of December 31, 2014, to be expensed over a weighted average period of 1.5 years (assumes minimal employee and director attrition and, if applicable, absolute return performance metrics being met for related initial measurement periods).
	All service-based stock awards receive dividends on a current basis without risk of forfeiture if the related awards do not vest.  Outstanding performance-based stock awards defer the payment of dividends accruing between the grant dates and the end of related performance periods.  If these awards do not vest, the related accrued dividends will be forfeited.  Included in Common stock dividend payable at December 31, 2014 and 2013 are estimated dividends payable pertaining to these awards totaling $1.4 million and $1.2 million, respectively.
	Long-term Equity-based Awards – Option Awards
	Option awards currently outstanding have ten-year contractual terms from the grant date and were issued with strike prices equal to the quoted market prices of Capstead’s common shares on the dates of grant, all of which were prior to 2010.  The fair value of option awards was estimated on the dates of grant using a Black-Scholes option pricing model and expensed over vesting periods that ended prior to 2012.  Option award activity for the year ended December 31, 2014 is summarized below:
		Number of Shares			Weighted Average Exercise Price
	Option awards outstanding at beginning of year		77,500		$	11.75
	Expirations		(10,000	)		14.41
	Exercises		(27,500	)		10.63
	Option awards outstanding at end of year		40,000			11.86
	All outstanding option awards are exercisable at December 31, 2014.  These awards have a weighted average remaining contractual term of 3.5 years and an aggregate intrinsic value of $26,000.  The total intrinsic value of option awards exercised was $67,000, $26,000 and $620,000 during 2014, 2013 and 2012, respectively.
	Other Benefit Programs
	Capstead sponsors a qualified defined contribution retirement plan for all employees and a nonqualified deferred compensation plan for certain of its executives.  In general the Company matches up to 50% of a participant’s voluntary contribution up to a maximum of 6% of a participant’s base salary and annual incentive compensation payments and makes discretionary contributions of up to another 3% of such compensation regardless of participation in the plans.  Company contributions are subject to certain vesting requirements that have been met by nearly all of Capstead’s current employees.  During 2014, 2013 and 2012, the Company recognized in Salaries and benefits $258,000, $320,000 and $406,000 related to contributions to these plans, respectively.

QUARTERLY_RESULTS_UNAUDITED

QUARTERLY RESULTS (UNAUDITED)	12 Months Ended
	Dec. 31, 2014
QUARTERLY RESULTS (UNAUDITED) [Abstract]
QUARTERLY RESULTS	NOTE 13 ¾ QUARTERLY RESULTS (UNAUDITED)
	Summarized quarterly results of operations were as follows (in thousands, except per share amounts).
			First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	Year Ended December 31, 2014
	Interest income on residential mortgage investments (before investment premium amortization)		$	81,733		$	82,233		$	82,146		$	82,509
	Investment premium amortization			(22,288	)		(25,141	)		(28,284	)		(26,159	)
	Related interest expense			(15,407	)		(15,542	)		(16,099	)		(18,107	)
				44,038			41,550			37,763			38,243
	Other interest income (expense) (a)			(2,061	)		(2,045	)		(2,044	)		(2,023	)
	Other revenue (expense)			(3,586	)		(2,941	)		(3,328	)		(2,746	)
	Net income		$	38,391		$	36,564		$	32,391		$	33,474
	Basic and diluted net income per common share		$	0.37		$	0.35		$	0.3		$	0.31
	Year Ended December 31, 2013
	Interest income on residential mortgage investments (before investment premium amortization)		$	86,867		$	85,214		$	85,674		$	83,254
	Investment premium amortization			(28,399	)		(33,642	)		(39,031	)		(24,800	)
	Related interest expense			(18,468	)		(16,749	)		(15,759	)		(15,392	)
				40,000			34,823			30,884			43,062
	Other interest income (expense) (a)			(2,010	)		(2,015	)		(2,074	)		(2,066	)
	Other revenue (expense)			(3,072	)		(2,914	)		(4,108	)		(4,023	)
	Net income		$	34,918		$	29,894		$	24,702		$	36,973
	Basic and diluted net income per common share (b)		$	0.31		$	0.04		$	0.23		$	0.35
	(a)	Consists principally of interest on unsecured borrowings and includes other interest income and is presented net of earnings of related statutory trusts.  The trusts were dissolved in December 2013.
	(b)	Includes $0.23 associated with redemption preference premiums paid and other one-time effects of the second quarter 2013 preferred capital transactions.

ACCOUNTING_POLICIES_Policies

ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2014
ACCOUNTING POLICIES [Abstract]
Basis of Presentation	Basis of Presentation
	The consolidated financial statements include the accounts of Capstead Mortgage Corporation and its wholly-owned and majority-owned subsidiaries over which it exercises control.  Capstead also consolidates, if appropriate, any variable interest entities in which it holds an interest.  Common securities held by the Company in statutory trusts organized to issue long-term unsecured borrowings (prior to the dissolution of these trusts in December 2013 – see NOTE 5) were not considered variable interests at risk pursuant to variable interest entity accounting principles and were accounted for as investments in unconsolidated affiliates.  Investments in any unconsolidated affiliates are initially recorded at cost and subsequently adjusted for the Company’s equity in earnings and losses and cash contributions and distributions.  Intercompany balances and transactions are eliminated.  Prior year amounts related to equity-based compensation for employees (see NOTE 12) have been reclassified from Salary and benefits to Long-term incentive compensation in the Statements of Income.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In June 2014 the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2014-11, Transfers and Servicing:  Repurchase-to-Maturity Transactions, Repurchase Financings and Disclosures (“ASU 2014-11”).  ASU 2014-11 requires repurchase-to-maturity transactions to be accounted for as financings and eliminates existing guidance regarding so-called “linked transactions” between a buyer of securities and a seller that also provides related repurchase financings.  ASU 2014-11 also introduces new disclosure requirements and is effective for periods beginning after December 15, 2014.  The adoption of ASU 2014-11 by the Company is not expected to have any effect on its results of operations, financial condition, or cash flows.
Use of Estimates	Use of Estimates
	The use of estimates is inherent in the preparation of financial statements.  Amortization of investment premiums on financial assets is based in part on estimates of future levels of mortgage prepayments, which are impacted by future changes in interest rates and other factors.  While the actual level of mortgage prepayments for a given accounting period is the single largest determinant in amortizing investment premiums, if expectations for future levels of mortgage prepayments increase substantially, earnings could be adversely affected.
	Fair values of financial instruments are estimated based on a market approach using available market information and appropriate valuation methodologies (Level Two Inputs); however, judgment is required in interpreting market data to develop these estimates.  Fair values fluctuate on a daily basis and are influenced by changes in, and market expectations for changes in, interest rates, market liquidity conditions and levels of mortgage prepayments, as well as other factors.  Accordingly, estimates of fair value are as of the balance sheet dates and are not necessarily indicative of the amounts that could be realized in a current market exchange.  The use of different market assumptions and estimation methodologies may have a material effect on estimated fair values.  Judgment is also exercised in making impairment conclusions and estimating impairment charges.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Cash and cash equivalents include unrestricted cash on hand and highly liquid investments with original maturities of three months or less when purchased.
Financial Assets	Financial Assets
	Capstead’s financial assets consist almost exclusively of Agency Securities classified as available-for-sale and carried at fair value with unrealized gains and losses reported as a separate component of Accumulated other comprehensive income.  Loans classified as held for investment or mortgage securities classified as held-to-maturity are recorded at amortized cost (unpaid principal balance, adjusted for unamortized investment premiums and discounts).  Interest is recorded as income when earned.  Investment premiums and discounts are recognized as adjustments to interest income by the interest method, generally over the expected life of the related financial assets. Realized gains and losses from sales are recorded as a component of Other revenue (expense).  The specific identification method is used to determine the cost of financial assets sold.  Financial assets are reviewed for potential impairment at each balance sheet date.  Other-than-temporary impairments of investments in mortgage securities can occur with changes in the Company’s intent or ability to hold the mortgage securities until any declines in fair value are recovered and as a result of adverse changes in the financial condition of the issuer(s) such that a full recovery of cost basis is no longer expected.  The amount of any such other-than-temporary impairment for an investment in a mortgage security is measured by comparing the recorded amount of the security to its fair value.  Other-than-temporary impairment charges would be recorded as a component of Other revenue (expense) if the impairment results from changes in in the Company’s intent or ability to hold the securities.  Should other-than-temporary impairment arise as a result of adverse changes in the financial condition of the issuer(s) without changing the Company’s intent and ability to hold the securities, the credit component of the impairment would be recorded as a component of Other revenue (expense) and with any remainder recorded as a component of Other comprehensive income.
Borrowings	Borrowings
	Capstead’s borrowings are carried at their principal balances outstanding.  Debt issue costs associated with Unsecured borrowings are recorded in Receivables and other assets, and are recognized as adjustments to interest expense by the interest method over the term of these borrowings.
	Borrowings under repurchase arrangements create exposure to the potential for failure on the part of counterparties to honor their commitment to return pledged collateral.  In the event of a default by a counterparty, the Company may have difficulty recovering its collateral.  To mitigate this risk, the Company monitors the creditworthiness of its counterparties and manages its exposure to any single counterparty.
Derivative Financial Instruments ("Derivatives")	Derivative Financial Instruments (“Derivatives”)
	Derivatives used by Capstead for risk management purposes are carried at fair value as assets or liabilities.  The accounting for changes in fair value of each Derivative held depends on whether it has been designated as a hedge for accounting purposes, as well as the type of hedging relationship identified.  Capstead will typically designate any Derivatives held as cash flow hedges related to a designated portion of its current and anticipated future borrowings.  To qualify as a cash flow hedge, at the inception of the hedge relationship the Company must document that the hedge relationship is anticipated to be highly effective and monitor ongoing effectiveness on at least a quarterly basis.  As long as the hedge relationship remains effective, the effective portion of changes in fair value of the Derivative is recorded in Accumulated other comprehensive income and the ineffective portion is recorded in interest expense.  The effective portion of changes in fair value is reclassified from Accumulated other comprehensive income to earnings over the term of the Derivative primarily in the form of Derivative cash flows that are either in excess of or lower than market rates.  Changes in fair value of Derivatives not held as accounting hedges, if any, or for which the hedge relationship is no longer considered highly effective, are recorded in Miscellaneous other revenue (expense).
	The Company uses interest rate swap agreements in cash flow hedge relationships in order to hedge variability in borrowing rates due to changes in the underlying benchmark interest rate related to a designated portion of its current and anticipated future borrowings.  Variable-rate swap payments to be received and any measured hedge ineffectiveness are recorded in interest expense as an offset to interest owed on the hedged borrowings that reset to market rates generally every 30 to 90 days.  Fixed-rate swap payments to be made are also recorded in interest expense.  The combination of these cash flows results in a relatively fixed rate on these borrowings, subject to certain adjustments.  These adjustments include changes in spreads between variable rates on the swap agreements and actual borrowing rates as well as the effects of measured hedge ineffectiveness.
	Holding Derivatives creates exposure to credit risk related to the potential for failure on the part of counterparties to honor their commitments.  In addition, the Company is required to post collateral based on any declines in the market value of the Derivatives.  In the event of default by a counterparty, the Company may have difficulty recovering its collateral and may not receive payments provided for under the terms of the Derivative.  To mitigate this risk, the Company uses only well-established commercial banks as counterparties and, pursuant to recent regulatory changes, most Derivatives held at December 31, 2014 were entered into through exchanges designed in part to mitigate credit risk.
	Cash collateral receivable from interest rate swap counterparties represents cash remitted to swap counterparties to meet initial and ongoing margin requirements that are based on the fair value of these Derivatives, including related interest receivable or payable under the terms of the agreements.  The Company may also remit mortgage securities to certain of its swap counterparties to meet ongoing margin requirements.  Such mortgage securities, if any, are included in Residential mortgage investments.  Similarly, Cash collateral payable to interest rate swap counterparties represents cash received from counterparties to meet margin call requirements.  For presentation purposes, the Company does not offset individual counterparty collateral receivables (or payables) with the recorded fair value of related interest rate swap agreements pursuant to master netting arrangements.  In addition, gross unrealized gains on Derivatives (recorded as assets) are stated separately from gross unrealized losses (recorded as liabilities) without regard to counterparty.
Long-term Incentive Compensation	Long-term Incentive Compensation
	Capstead provides its employees and its directors with long-term incentive compensation in the form of equity-based awards.  Equity-based compensation costs are initially measured at the estimated fair value of the awards on the grant date developed using appropriate valuation methodologies, as adjusted for estimates of future award forfeitures.  Valuation methodologies used and subsequent expense recognition is dependent upon each award’s service and performance conditions, the latter also referred to as performance metrics.
	Compensation costs for stock awards subject only to service conditions are measured at the closing stock price on the dates of grant and are recognized as expense on a straight-line basis over the requisite service periods for the awards, as adjusted for changes in estimated, and ultimately actual, forfeitures.  Compensation costs for components of stock awards and restricted stock units (“RSUs”) subject to nonmarket-based performance metrics, (i.e. metrics not predicated on changes in the Company’s stock price) are measured at the closing stock price on the dates of grant, adjusted for the probability of achieving certain benchmarks included in the performance metrics.  These initial cost estimates are recognized as expense over the requisite performance periods, as adjusted for changes in estimated, and ultimately actual, forfeitures and performance.  Compensation costs for components of RSUs subject to market-based performance metrics are measured at the dates of grant using a Monte Carlo simulation model which incorporates into the valuation the inherent uncertainty regarding the achievement of the market-based performance metrics.  These initial valuation amounts are recognized as expense over the requisite performance periods, subject only to adjustments for changes in estimated, and ultimately actual, forfeitures.
Income Taxes	Income Taxes
	Capstead Mortgage Corporation and its qualified REIT subsidiaries (“Capstead REIT”) have elected to be taxed as a REIT.  As a result, Capstead REIT is not taxed on taxable income distributed to stockholders if certain REIT qualification tests are met.  Capstead’s policy is to distribute 100% of the taxable income of the REIT, after application of available tax attributes, within the time limits prescribed by the Internal Revenue Code (the “Code”), which may extend into the subsequent taxable year.  The Company may find it advantageous from time to time to elect taxable REIT subsidiary status for certain of its subsidiaries in which case taxable income of any such subsidiary would be subject to federal and, where applicable, state or local income taxes.  Any such income taxes are accounted for using the liability method.  Related deferred income tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse.
	The Company has not recognized any liabilities for unrecognized tax benefits using a “more likely than not” threshold for the recognition and measurement of the financial statement effects of tax positions taken on a tax return filing.  Should any such liabilities be recognized in future periods, the Company will record related interest and penalties in Other general and administrative expense.
Dividend Classification	Dividend Classification
	Capstead records common and preferred stock dividends in the Accumulated deficit component of Stockholders’ equity only to the extent of available earnings for the related period.  Any dividends declared in excess of available earnings are considered a return of capital for financial reporting purposes and are recorded as reductions of Paid-in capital.  The tax and financial reporting classification of dividends can differ primarily as a result of differences between taxable income and Net income and how taxable income is allocated to dividends paid.

NET_INCOME_PER_COMMON_SHARE_Ta

NET INCOME PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2014
NET INCOME PER COMMON SHARE [Abstract]
Components Of Computation Of Basic And Diluted Net Income Per Common Share	Components of the computation of basic and diluted net income per common share were as follows for the indicated periods (dollars in thousands, except per share amounts):
		Year ended December 31
		2014			2013			2012
	Basic net income per common share
	Numerator for basic net income per common share:
	Net income	$	140,820		$	126,487		$	163,626
	Redemption preference premiums paid on Convertible preferred stock		–			(19,924	)		–
	Preferred stock dividends		(13,781	)		(17,536	)		(21,021	)
	Earnings participation of unvested equity awards		(95	)		(139	)		(372	)
		$	126,944		$	88,888		$	142,233
	Denominator for basic net income per common share:
	Weighted average common stock outstanding		95,789			95,679			95,115
	Average unvested stock awards outstanding		(398	)		(506	)		(522	)
			95,391			95,173			94,593
		$	1.33		$	0.93		$	1.5
	Diluted net income per common share
	Numerator for diluted net income per common share:
	Numerator for basic net income per common share	$	126,944		$	88,888		$	142,233
	Dividends on dilutive convertible preferred stock		–			44			298
		$	126,944		$	88,932		$	142,531
	Denominator for diluted net income per common share:
	Denominator for basic net income per common share		95,391			95,173			94,593
	Net effect of dilutive equity awards		238			145			111
	Net effect of dilutive convertible preferred stock		–			75			308
			95,629			95,393			95,012
		$	1.33		$	0.93		$	1.5
Potentially Dilutive Securities Excluded From Computation Of Net Income Per Common Share	Securities that could be potentially dilutive in the future that were not included in the computation of diluted net income per common share because to do so would have been antidilutive during the indicated periods were as follows (in thousands):
		Year ended December 31
		2014			2013			2012
	Antidilutive convertible preferred stock		–			–			16,493
	Antidilutive equity awards excludable under the treasury stock method:
	Shares issuable under option awards		15			30			10
	RSUs		–			243			–

RESIDENTIAL_MORTGAGE_INVESTMEN1

RESIDENTIAL MORTGAGE INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
RESIDENTIAL MORTGAGE INVESTMENTS [Abstract]
Schedule Of Residential Mortgage Investments	Residential mortgage investments classified by collateral type and interest rate characteristics were as follows as of the indicated dates (dollars in thousands):
			Unpaid		Investment Premiums		Amortized Cost Basis		Carrying		Net			Average
			Principal						Amount (a)		WAC (b)			Yield(b)
			Balance
	31-Dec-14
	Agency Securities:
	Fannie Mae/Freddie Mac:
	Fixed-rate		$	1,660	$	4	$	1,664	$	1,665		6.63	%		6.45	%
	ARMs			10,230,419		328,781		10,559,200		10,800,332		2.51			1.72
	Ginnie Mae ARMs			2,983,659		103,911		3,087,570		3,099,168		2.63			1.53
				13,215,738		432,696		13,648,434		13,901,165		2.54			1.69
	Residential mortgage loans:
	Fixed-rate			1,848		2		1,850		1,850		6.96			5.46
	ARMs			3,046		13		3,059		3,059		3.73			3.14
				4,894		15		4,909		4,909		4.95			3.97
	Collateral for structured financings			1,997		33		2,030		2,030		8.11			7.62
			$	13,222,629	$	432,744	$	13,655,373	$	13,908,104		2.54			1.69
	31-Dec-13
	Agency Securities:
	Fannie Mae/Freddie Mac:
	Fixed-rate		$	2,158	$	6	$	2,164	$	2,167		6.67	%		6.4	%
	ARMs			10,675,620		343,452		11,019,072		11,231,057		2.58			1.59
	Ginnie Mae ARMs			2,145,639		74,396		2,220,035		2,233,495		2.64			1.57
				12,823,417		417,854		13,241,271		13,466,719		2.59			1.59
	Residential mortgage loans:
	Fixed-rate			2,633		3		2,636		2,636		6.99			5.62
	ARMs			4,244		18		4,262		4,262		3.81			3.46
				6,877		21		6,898		6,898		5.03			4.27
	Collateral for structured financings			2,220		37		2,257		2,257		8.09			7.34
			$	12,832,514	$	417,912	$	13,250,426	$	13,475,874		2.59			1.59
	(a)	Includes unrealized gains and losses for residential mortgage investments classified as available-for-sale (see NOTE 9).
	(b)	Net WAC, or weighted average coupon, is the weighted average interest rate of the mortgage loans underlying the indicated investments net of servicing and other fees as of the indicated balance sheet date.  Net WAC is expressed as a percentage calculated on an annualized basis on the unpaid principal balances of the mortgage loans underlying these investments.  Average yield is presented for the year then ended, and is based on the cash component of interest income expressed as a percentage calculated on an annualized basis on average amortized cost basis (the “cash yield”) less the effects of amortizing investment premiums.  Investment premium amortization is determined using the interest method and incorporates actual and anticipated future mortgage prepayments.

REPURCHASE_ARRANGEMENTS_AND_SI1

REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2014
REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS [Abstract]
Schedule Of Repurchase Arrangements And Similar Borrowings	Repurchase arrangements and similar borrowings (and related pledged collateral, including accrued interest receivable), classified by collateral type and remaining maturities, and related weighted average borrowing rates as of the indicated dates were as follows (dollars in thousands):
	Collateral Type		Collateral		Accrued			Borrowings		Average
			Carrying		Interest			Outstanding		Borrowing
			Amount		Receivable					Rates
	31-Dec-14
	Borrowings with maturities of 30 days or less:
	Agency Securities		$	10,401,080	$	24,045		$	9,878,889		0.35	%
	Borrowings with maturities greater than 30 days:
	Agency Securities (31 to 90 days)			1,205,570		2,248			1,150,924		0.35
	Agency Securities (greater than 90 days)			1,874,892		4,640			1,775,000		0.56
	Similar borrowings:
	Collateral for structured financings*			2,030		–			2,030		8.11
			$	13,483,572	$	30,933		$	12,806,843		0.38
	Year-end borrowing rates adjusted for effects of related Derivatives (see NOTE 7)										0.58
	31-Dec-13
	Borrowings with maturities of 30 days or less:
	Agency Securities		$	12,169,534	$	28,195		$	11,578,211		0.38	%
	Borrowings with maturities greater than 30 days:
	Agency Securities (31 to 90 days)			951,966		2,068			902,432		0.38
	Similar borrowings:
	Collateral for structured financings*			2,257		–			2,257		8.09
			$	13,123,757	$	30,263		$	12,482,900		0.38
	Year-end borrowing rates adjusted for effects of related Derivatives held as cash flow hedges										0.49
	*	The maturity of structured financings is directly affected by prepayments on the related mortgage pass-through securities pledged as collateral.  Additionally, these financings are subject to redemption by the residual bondholders.
Schedule Of Average Borrowings Outstanding	Average borrowings outstanding differed from respective year-end balances during the indicated periods primarily due to changes in portfolio levels and differences in the timing of portfolio acquisitions relative to portfolio runoff as illustrated below (dollars in thousands):
			Year ended December 31
			2014					2013
			Average		Average			Average		Average
			Borrowings		Rate			Borrowings		Rate
	Average borrowings and rates adjusted for the effects of related Derivatives held as cash flow hedges for the indicated years		$	12,651,061		0.52	%	$	12,702,941		0.52	%

USE_OF_DERIVATIVE_FINANCIAL_IN1

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT (Tables)	12 Months Ended
	Dec. 31, 2014
USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT [Abstract]
Schedule of Swap Agreements Expiration Period and Characteristics	At December 31, 2014, the Company’s portfolio of financing-related swap positions had the following characteristics (dollars in thousands):
	Period of		Notional				Average Fixed Rate
	Contract Expiration		Amount				Payment Requirement
	Currently-paying contracts:
	First quarter 2015		$	1,100,000				0.5	%
	Second quarter 2015			200,000				0.43
	Third quarter 2015			400,000				0.47
	Fourth quarter 2015			1,200,000				0.45
	First quarter 2016			1,700,000				0.51
	Second quarter 2016			1,100,000				0.47
	Third quarter 2016			700,000				0.56
	Fourth quarter 2016			800,000				0.66
	(average expiration: 12 months)			7,200,000				0.51
	Forward-starting contracts:
	First quarter 2017 (average expiration: 24 months)			500,000				0.72
	(average expiration: 12 months)		$	7,700,000
Impact of Derivative Instruments on Statements of Financial Performance and Financial Position	The following tables include fair value and other related disclosures regarding all Derivatives held as of and for the indicated periods (in thousands):
		Balance Sheet		31-Dec
		Location		2014				2013
	Balance sheet-related
	Swap agreements in a gain position (an asset) related to:
	Borrowings under repurchase arrangements	(a)		$	1,657			$	1,094
	Unsecured borrowings	(a)			–				3,911
	Swap agreements in a loss position (a liability) related to:
	Borrowings under repurchase arrangements	(a)			(6,332	)			(11,304	)
	Unsecured borrowings	(a)			(20,702	)			–
	Related net interest payable	(b)			(9,516	)			(5,493	)
				$	(34,893	)		$	(11,792	)
	(a)	The fair value of Derivatives with realized and unrealized gains are aggregated and recorded as an asset on the face of the Balance Sheets separately from the fair value of Derivatives with realized and unrealized losses that are recorded as a liability.  The amount of unrealized losses scheduled to be recognized in the Statements of Income over the next twelve months primarily in the form of fixed-rate swap payments in excess of current market rates totaled $12.2 million at December 31, 2014.
	(b)	Included in “Accounts payable and accrued expenses” on the face of the Balance Sheets.
			Location of Gain or (Loss) Recognized in				Year ended December 31
			Net Income				2014				2013			2012
	Income statement-related
	Components of effect on interest expense:
	Amount of loss reclassified from Accumulated other comprehensive income related to the effective portion of active positions						$	(22,055	)		$	(16,914	)	$	(19,882	)
	Amount of gain (loss) recognized (ineffective portion)							(473	)			24			(542	)
	Increase in interest expense and decrease in Net income as a result of the use of Derivatives			*			$	(22,528	)		$	(16,890	)	$	(20,424	)
	Other comprehensive income-related
	Amount of gain (loss) recognized in Other comprehensive income (loss) (effective portion)						$	(41,059	)		$	9,320		$	(22,262	)
		*	Included in “Interest expense:  Repurchase arrangements and similar borrowings” on the face of the Statements of Income.
Schedule of Offsetting Disclosures for Asset Derivatives Held and Repurchase Arrangements and Similar Borrowings Outstanding	Capstead’s swap agreements and borrowings under repurchase arrangements are subject to master netting arrangements in the event of default on, or termination of, any one contract.  See NOTE 6 for more information on the Company’s use of repurchase arrangements.  The following tables provide disclosures concerning offsetting of financial liabilities and Derivatives as of the indicated dates (in thousands):
			Offsetting of Derivative Asset
			Gross				Gross				Net Amounts			Gross Amounts Not Offset
							Amounts				of Assets			in the Balance Sheet(a)
			Amounts of				Offset in				Presented in			Financial Instruments			Cash Collateral Received			Net
			Recognized				the Balance				the Balance									Amount
			Assets				Sheet				Sheet
	31-Dec-14
	Counterparty 2		$	–			$	95			$	95		$	(95	)	$	–		$	–
	Counterparty 4			1,128				434				1,562			(1,562	)		–			–
			$	1,128			$	529			$	1,657		$	(1,657	)	$	–		$	–
	31-Dec-13
	Counterparty 1		$	3,911			$	–			$	3,911		$	(3,911	)	$	–		$	–
	Counterparty 2			634				–				634			(634	)		–			–
	Counterparty 4			460				–				460			(460	)		–			–
			$	5,005			$	–			$	5,005		$	(5,005	)	$	–		$	–
Schedule of Offsetting Disclosures for Liability Derivatives Held and Repurchase Arrangements and Similar Borrowings Outstanding			Offsetting of Financial Liabilities and Derivative Liabilities
			Gross				Gross				Net Amounts			Gross Amounts Not Offset
							Amounts				of Liabilities			in the Balance Sheet (c)
			Amounts of				Offset in				Presented in			Financial			Cash			Net
			Recognized				the Balance				the Balance			Instruments			Collateral			Amount
			Liabilities(b)				Sheet				Sheet (a)						Pledged
	31-Dec-14
	Derivatives by counterparty:
	Counterparty 1		$	24,533			$	–			$	24,533		$	–		$	(24,533	)	$	–
	Counterparty 2			4,042				95				4,137			(95	)		(4,042	)		–
	Counterparty 3			736				–				736			–			(736	)		–
	Counterparty 4			6,710				434				7,144			(1,562	)		(5,582	)		–
				36,021				529				36,550			(1,657	)		(34,893	)		–
	Repurchase arrangements and similar borrowings			12,812,947				–				12,812,947			(12,812,947	)		–			–
			$	12,848,968			$	529			$	12,849,497		$	(12,814,604	)	$	(34,893	)	$	–
	31-Dec-13
	Derivatives by counterparty:
	Counterparty 1		$	6,002			$	–			$	6,002		$	(3,911	)	$	(2,091	)	$	–
	Counterparty 2			6,352				–				6,352			(634	)		(5,718	)		–
	Counterparty 3			1,581				–				1,581			–			(1,581	)		–
	Counterparty 4			2,862				–				2,862			(460	)		(2,402	)		–
				16,797				–				16,797			(5,005	)		(11,792	)		–
	Repurchase arrangements and similar borrowings			12,487,604				–				12,487,604			(12,487,604	)		–			–
			$	12,504,401			$	–			$	12,504,401		$	(12,492,609	)	$	(11,792	)	$	–
	(a)	Amounts presented are limited to recognized liabilities and cash collateral received associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.
	(b)	Amounts include accrued interest of $9.5 million and $5.5 million on interest rate swap agreements and $6.1 million and $4.7 million on repurchase arrangements and similar borrowings, included in “Accounts payable and accrued expenses” on the face of the Balance Sheets as of December 31, 2014 and December 31, 2013, respectively.
	(c)	Amounts presented are limited to recognized assets and collateral pledged associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.
Changes in Accumulated Other Comprehensive Income	Changes in Accumulated other comprehensive income by component for the three years ended December 31, 2014 were as follows (in thousands):
			Gains and Losses				Unrealized Gains				Total
			on Cash Flow				and Losses on
			Hedges				Available-for-Sale
							Securities
	Balance at December 31, 2011		$	(30,159	)		$	234,699			$	204,540
	Activity for the year ended December 31, 2012:
	Other comprehensive income (loss) before reclassifications			(22,262	)			91,750				69,488
	Amounts reclassified from accumulated other comprehensive income			19,882				–				19,882
	Other comprehensive income (loss)			(2,380	)			91,750				89,370
	Balance at December 31, 2012			(32,539	)			326,449				293,910
	Activity for the year ended December 31, 2013:
	Other comprehensive income (loss) before reclassifications			9,320				(101,001	)			(91,681	)
	Amounts reclassified from accumulated other comprehensive income			16,914				–				16,914
	Other comprehensive income (loss)			26,234				(101,001	)			(74,767	)
	Balance at December 31, 2013			(6,305	)			225,448				219,143
	Activity for the year ended December 31, 2014:
	Other comprehensive income (loss) before reclassifications			(41,059	)			27,283				(13,776	)
	Amounts reclassified from accumulated other comprehensive income			22,055				–				22,055
	Other comprehensive income (loss)			(19,004	)			27,283				8,279
	Balance at December 31, 2014		$	(25,309	)		$	252,731			$	227,422

UNSECURED_BORROWINGS_Tables

UNSECURED BORROWINGS (Tables)	12 Months Ended
	Dec. 31, 2014
UNSECURED BORROWINGS [Abstract]
Schedule Of Subordinated Note Balances And Related Weighted Average Interest Rates			31-Dec-14					31-Dec-13
			Borrowings		Average			Borrowings		Average
			Outstanding		Rate *			Outstanding		Rate *
	Junior subordinated notes associated with:
	Capstead Mortgage Trust I		$	35,000		8.31	%	$	35,000		8.31	%
	Capstead Mortgage Trust II			40,000		8.46			40,000		8.46
	Capstead Mortgage Trust III			25,000		8.78			25,000		8.78
			$	100,000		8.49		$	100,000		8.49
	*	The indicated weighted average rates have been in effect since issuance.  After considering cash flow hedges that coincide with the floating rate terms of these borrowings that begin October 30, and December 15, 2015 for the notes associated with Capstead Mortgage Trusts I and II and September 15, 2016 for the notes associated with Capstead Mortgage Trust III, the effective borrowing rate will average 7.56% beginning September 15, 2016 through maturity, subject to certain adjustments for the effects of measured hedge ineffectiveness, if any.

DISCLOSURES_REGARDING_FAIR_VAL1

DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS [Abstract]
Financial Instruments Other Than Debt Securities	Fair value-related disclosures for financial instruments other than debt securities were as follows as of the indicated dates (in thousands):
		31-Dec-14				31-Dec-13
		Carrying		Fair		Carrying		Fair
		Amount		Value		Amount		Value
	Financial assets:
	Residential mortgage loans	$	4,909	$	5,000	$	6,898	$	7,000
	Interest rate swap agreements		1,657		1,657		5,005		5,005
	Financial liabilities:
	Repurchase arrangements with initial terms of greater than 120 days		2,128,517		2,128,400		36,299		36,300
	Unsecured borrowings		100,000		100,500		100,000		101,000
	Interest rate swap agreements		27,034		27,034		11,304		11,304
Fair Value And Related Disclosures For Debt Securities	Fair value-related disclosures for debt securities were as follows as of the indicated dates (in thousands):
		Amortized		Gross Unrealized
		Cost Basis		Gains		Losses		Fair Value
	31-Dec-14
	Agency Securities classified as available-for-sale:
	Fannie Mae/Freddie Mac	$	10,559,231	$	243,351	$	2,218	$	10,800,364
	Ginnie Mae		3,087,570		16,755		5,157		3,099,168
	Residential mortgage securities classified as held-to-maturity		3,663		124		–		3,787
	31-Dec-13
	Agency Securities classified as available-for-sale:
	Fannie Mae/Freddie Mac		11,019,116		224,456		12,468		11,231,104
	Ginnie Mae		2,220,035		18,384		4,924		2,233,495
	Residential mortgage securities classified as held-to-maturity		4,376		211		–		4,587
Securities In Unrealized Loss Position		31-Dec-14				31-Dec-13
		Fair		Unrealized		Fair		Unrealized
		Value		Loss		Value		Loss
	Securities in an unrealized loss position:
	One year or greater	$	706,839	$	5,320	$	39,030	$	380
	Less than one year		1,095,724		2,055		2,857,724		17,012
		$	1,802,563	$	7,375	$	2,896,754	$	17,392

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
INCOME TAXES [Abstract]
Schedule Of Effective Income Tax Rate Reconciliation	The Company’s effective tax rate differs substantially from statutory federal income tax rates primarily due to the benefit of Capstead REIT’s status as a REIT, along with other items affecting the Company’s effective tax rate as illustrated below for the indicated periods (in thousands):
			Year ended December 31
			2014			2013			2012
	Income taxes computed at the federal statutory rate		$	49,287		$	44,270		$	57,269
	Benefit of REIT status			(49,28	)		(44,270	)		(57,268	)
	Income taxes computed on income of Capstead’s sole taxable REIT subsidiary			4			–			1
	Change in net deferred income tax assets			(4	)		1			(1	)
	Other			–			(1	)		–
	Income tax provision		$	–		$	–		$	–
Components Of Deferred Tax Assets And Liabilities	No income taxes were paid during 2014, 2013 or 2012.  Significant components of the Company’s taxable REIT subsidiary’s deferred income tax assets and liabilities were as follows as of the indicated dates (in thousands):
			31-Dec
			2014			2013
	Deferred income tax assets:
	Alternative minimum tax credit (a)		$	1,941		$	1,942
	Net operating loss carryforwards (b)			58			60
	Other			20			21
				2,019			2,023
	Deferred income tax liabilities			–			–
	Net deferred tax assets		$	2,019		$	2,023
	Valuation allowance (c)		$	2,019		$	2,023
		(a)	Alternative minimum tax credit carryforwards can be utilized to offset payment of federal income taxes on future taxable income, if any, earned by this subsidiary, subject to certain limitations.
		(b)	Excludes $3.5 million in remaining net operating loss carryforwards which expire beginning after 2019.  To the extent these carryforwards are utilized in future periods, the benefit will reduce actual taxes payable.
		(c)	Because this subsidiary is not expected to earn significant amounts of taxable income, related net deferred tax assets are fully reserved at December 31, 2014.

STOCKHOLDERS_EQUITY_Tables

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2014
STOCKHOLDERS EQUITY [Abstract]
Schedule of Series E Preferred Stock Issued Prices and Proceeds Presented Net of Underwriting Fees and Other Costs	In late 2013 Capstead began issuing additional shares of Series E preferred stock through an at-the-market continuous offering program.  Shares of Series E preferred stock issued under this program, issue prices and proceeds, both presented net of underwriting fees and other costs were as follows for the indicated periods:
		Shares		Net		Net
				Issue Price		Proceeds
	Year ended December 31, 2013		61,000	$	23.78	$	1,447,000
	Year ended December 31, 2014		757,000		24.01		18,180,000
	Subsequent to year-end through February 27, 2015 (unaudited)		222,000		24.65		5,465,000

COMPENSATION_PROGRAMS_Tables

COMPENSATION PROGRAMS (Tables)	12 Months Ended
	Dec. 31, 2014
COMPENSATION PROGRAMS [Abstract]
Schedule Of Performance- And Service- Based Stock Award Activity	Performance-based and service-based stock award activity for year ended December 31, 2014 is summarized below:
		Number of			Weighted Average
		Shares			Grant Date
					Fair Value
	Unvested stock awards outstanding at beginning of year		528,931		$	12.51
	Grants		72,237			12.8
	Vestings		(164,587	)		13.23
	Unvested stock awards outstanding at end of year		436,581			12.29
Schedule Of Option Award Activity	Option awards currently outstanding have ten-year contractual terms from the grant date and were issued with strike prices equal to the quoted market prices of Capstead’s common shares on the dates of grant, all of which were prior to 2010.  The fair value of option awards was estimated on the dates of grant using a Black-Scholes option pricing model and expensed over vesting periods that ended prior to 2012.  Option award activity for the year ended December 31, 2014 is summarized below:
		Number of Shares			Weighted Average Exercise Price
	Option awards outstanding at beginning of year		77,500		$	11.75
	Expirations		(10,000	)		14.41
	Exercises		(27,500	)		10.63
	Option awards outstanding at end of year		40,000			11.86

QUARTERLY_RESULTS_Tables

QUARTERLY RESULTS (Tables)	12 Months Ended
	Dec. 31, 2014
QUARTERLY RESULTS (UNAUDITED) [Abstract]
Summarized Quarterly Results Of Operations	NOTE 13 ¾ QUARTERLY RESULTS (UNAUDITED)
	Summarized quarterly results of operations were as follows (in thousands, except per share amounts).
			First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	Year Ended December 31, 2014
	Interest income on residential mortgage investments (before investment premium amortization)		$	81,733		$	82,233		$	82,146		$	82,509
	Investment premium amortization			(22,288	)		(25,141	)		(28,284	)		(26,159	)
	Related interest expense			(15,407	)		(15,542	)		(16,099	)		(18,107	)
				44,038			41,550			37,763			38,243
	Other interest income (expense) (a)			(2,061	)		(2,045	)		(2,044	)		(2,023	)
	Other revenue (expense)			(3,586	)		(2,941	)		(3,328	)		(2,746	)
	Net income		$	38,391		$	36,564		$	32,391		$	33,474
	Basic and diluted net income per common share		$	0.37		$	0.35		$	0.3		$	0.31
	Year Ended December 31, 2013
	Interest income on residential mortgage investments (before investment premium amortization)		$	86,867		$	85,214		$	85,674		$	83,254
	Investment premium amortization			(28,399	)		(33,642	)		(39,031	)		(24,800	)
	Related interest expense			(18,468	)		(16,749	)		(15,759	)		(15,392	)
				40,000			34,823			30,884			43,062
	Other interest income (expense) (a)			(2,010	)		(2,015	)		(2,074	)		(2,066	)
	Other revenue (expense)			(3,072	)		(2,914	)		(4,108	)		(4,023	)
	Net income		$	34,918		$	29,894		$	24,702		$	36,973
	Basic and diluted net income per common share (b)		$	0.31		$	0.04		$	0.23		$	0.35
	(a)	Consists principally of interest on unsecured borrowings and includes other interest income and is presented net of earnings of related statutory trusts.  The trusts were dissolved in December 2013.
	(b)	Includes $0.23 associated with redemption preference premiums paid and other one-time effects of the second quarter 2013 preferred capital transactions.

ACCOUNTING_POLICIES_Details

ACCOUNTING POLICIES (Details)	12 Months Ended
	Dec. 31, 2014
Income Taxes [Abstract]
Percentage of taxable income to be distributed (in hundredths)	100.00%
Minimum [Member]
Derivative [Line Items]
Interest owed on hedged borrowings rest to market rates (in days)	30 days
Maximum [Member]
Derivative [Line Items]
Interest owed on hedged borrowings rest to market rates (in days)	90 days

NET_INCOME_PER_COMMON_SHARE_Co

NET INCOME PER COMMON SHARE - Components of Computation of Basic and Diluted Net Income Per Common Share (Details) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Numerator for basic net income per common share [Abstract]
Net income	$140,820	$126,487	$163,626
Redemption preference premiums paid on Convertible preferred stock	0	-19,924	0
Preferred stock dividends	-13,781	-17,536	-21,021
Earnings participation of unvested equity awards	-95	-139	-372
Numerator for basic net income per common share	126,944	88,888	142,233
Denominator for basic net income per common share [Abstract]
Weighted average common stock outstanding (in shares)	95,789	95,679	95,115
Average unvested stock awards outstanding (in shares)	-398	-506	-522
Denominator for basic net income per common share (in shares)	95,391	95,173	94,593
Basic net income per common share (in dollars per share)	$1.33	$0.93	$1.50
Numerator for diluted net income per common share [Abstract]
Numerator for basic net income per common share	126,944	88,888	142,233
Dividends on dilutive convertible preferred stock	0	44	298
Numerator for diluted net income per common share	$126,944	$88,932	$142,531
Denominator for diluted net income per common share [Abstract]
Denominator for basic net income per common share	95,391	95,173	94,593
Net effect of dilutive equity awards (in shares)	238	145	111
Net effect of dilutive convertible preferred stock (in shares)	0	75	308
Denominator for diluted net income per common share (in shares)	95,629	95,393	95,012
Diluted net income per common share (in dollars per share)	$1.33	$0.93	$1.50

NET_INCOME_PER_COMMON_SHARE_Po

NET INCOME PER COMMON SHARE - Potentially Dilutive Securities Excluded from Computation of Net Income Per Common Share (Details)	12 Months Ended			1 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	31-May-13
Schedule of Earning Per Share, Basic, by Common Class [Line Items]
Antidilutive convertible preferred shares (in shares)	0	0	16,493
Shares issuable under option awards (in shares)	15	30	10
RSUs (in shares)	0	243	0
7.50% Cumulative Redeemable Preferred Stock, Series E [Member]
Schedule of Earning Per Share, Basic, by Common Class [Line Items]
Preferred stock dividend rate (in hundredths)				7.50%
Redeemable Preferred Stock [Member] | 7.50% Cumulative Redeemable Preferred Stock, Series E [Member]
Schedule of Earning Per Share, Basic, by Common Class [Line Items]
Preferred stock dividend rate (in hundredths)	7.50%

RESIDENTIAL_MORTGAGE_INVESTMEN2

RESIDENTIAL MORTGAGE INVESTMENTS - Schedule of Residential Mortgage Investments (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	$13,222,629		$12,832,514
Investment Premiums	432,744		417,912
Amortized Cost Basis	13,655,373		13,250,426
Carrying Amount	13,908,104	[1]	13,475,874	[1]
Net WAC (in hundredths)	2.54%	[2]	2.59%	[2]
Average Yield (in hundredths)	1.69%	[2]	1.59%	[2]
Agency Securities [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	13,215,738		12,823,417
Investment Premiums	432,696		417,854
Amortized Cost Basis	13,648,434		13,241,271
Carrying Amount	13,901,165	[1]	13,466,719	[1]
Net WAC (in hundredths)	2.54%	[2]	2.59%	[2]
Average Yield (in hundredths)	1.69%	[2]	1.59%	[2]
Agency Securities [Member] | Fixed-Rate [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	1,660		2,158
Investment Premiums	4		6
Amortized Cost Basis	1,664		2,164
Carrying Amount	1,665	[1]	2,167	[1]
Net WAC (in hundredths)	6.63%	[2]	6.67%	[2]
Average Yield (in hundredths)	6.45%	[2]	6.40%	[2]
Agency Securities [Member] | ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	10,230,419		10,675,620
Investment Premiums	328,781		343,452
Amortized Cost Basis	10,559,200		11,019,072
Carrying Amount	10,800,332	[1]	11,231,057	[1]
Net WAC (in hundredths)	2.51%	[2]	2.58%	[2]
Average Yield (in hundredths)	1.72%	[2]	1.59%	[2]
Agency Securities [Member] | Ginnie Mae ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	2,983,659		2,145,639
Investment Premiums	103,911		74,396
Amortized Cost Basis	3,087,570		2,220,035
Carrying Amount	3,099,168	[1]	2,233,495	[1]
Net WAC (in hundredths)	2.63%	[2]	2.64%	[2]
Average Yield (in hundredths)	1.53%	[2]	1.57%	[2]
Residential Mortgage Loans [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	4,894		6,877
Investment Premiums	15		21
Amortized Cost Basis	4,909		6,898
Carrying Amount	4,909	[1]	6,898	[1]
Net WAC (in hundredths)	4.95%	[2]	5.03%	[2]
Average Yield (in hundredths)	3.97%	[2]	4.27%	[2]
Residential Mortgage Loans [Member] | Fixed-Rate [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	1,848		2,633
Investment Premiums	2		3
Amortized Cost Basis	1,850		2,636
Carrying Amount	1,850	[1]	2,636	[1]
Net WAC (in hundredths)	6.96%	[2]	6.99%	[2]
Average Yield (in hundredths)	5.46%	[2]	5.62%	[2]
Residential Mortgage Loans [Member] | ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	3,046		4,244
Investment Premiums	13		18
Amortized Cost Basis	3,059		4,262
Carrying Amount	3,059	[1]	4,262	[1]
Net WAC (in hundredths)	3.73%	[2]	3.81%	[2]
Average Yield (in hundredths)	3.14%	[2]	3.46%	[2]
Collateral For Structured Financings [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Unpaid Principal Balance	1,997		2,220
Investment Premiums	33		37
Amortized Cost Basis	2,030		2,257
Carrying Amount	$2,030	[1]	$2,257	[1]
Net WAC (in hundredths)	8.11%	[2]	8.09%	[2]
Average Yield (in hundredths)	7.62%	[2]	7.34%	[2]
[1]	Includes unrealized gains and losses for residential mortgage investments classified as available-for-sale (see NOTE 9).
[2]	Net WAC, or weighted average coupon, is the weighted average interest rate of the mortgage loans underlying the indicated investments net of servicing and other fees as of the indicated balance sheet date. Net WAC is expressed as a percentage calculated on an annualized basis on the unpaid principal balances of the mortgage loans underlying these investments. Average yield is presented for the year then ended, and is based on the cash component of interest income expressed as a percentage calculated on an annualized basis on average amortized cost basis (the "cash yield") less the effects of amortizing investment premiums. Investment premium amortization is determined using the interest method and incorporates actual and anticipated future mortgage prepayments.

RESIDENTIAL_MORTGAGE_INVESTMEN3

RESIDENTIAL MORTGAGE INVESTMENTS - Narrative (Details) (USD $)	12 Months Ended
In Billions, unless otherwise specified	Dec. 31, 2014
Schedule Of Residential Mortgage Investments [Line Items]
Mortgage securities weighted average contractual maturity, months	290 months
Available for sale ARM securities, current-reset	$7.67
Available for sale ARM securities, longer-to-reset	$5.98
Current-Reset ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Agency securities average months to roll, months	6 months 12 days
Current-Reset ARMs [Member] | Maximum [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Agency securities months to roll	18 months
Longer-To-Reset ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Agency securities average months to roll, months	39 months 15 days
Longer-To-Reset ARMs [Member] | Minimum [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Agency securities months to roll	18 months

INVESTMENTS_IN_UNCONSOLIDATED_1

INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
INVESTMENTS IN UNCONSOLIDATED AFFILIATES [Abstract]
Issuance of common securities	$3.10

REPURCHASE_ARRANGEMENTS_AND_SI2

REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS - Narrative (Details) (Repurchase Arrangements And Similar Borrowings [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Repurchase Arrangements And Similar Borrowings [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Interest paid on Repurchase arrangements and similar borrowings	$59.70	$71.10	$69.50

REPURCHASE_ARRANGEMENTS_AND_SI3

REPURCHASE ARRANGEMENTS AND SIMILAR BORROWINGS - Collateral and Rates (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Collateral Carrying Amount	$13,480,000		$13,120,000
Borrowings Outstanding	12,806,843		12,482,900
Average borrowings adjusted amount	12,651,061		12,702,941
Average borrowings rates adjusted for effects related cash flow derivatives (in hundredths)	0.52%		0.52%
Year-End Borrowing Rates Adjusted For Effects Of Related Derivatives Held As Cash Flow Hedges [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Average Borrowing Rates (in hundredths)	0.58%		0.49%
Agency Securities [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Collateral Carrying Amount	13,483,572		13,123,757
Accrued Interest Receivable	30,933		30,263
Borrowings Outstanding	12,806,843		12,482,900
Average Borrowing Rates (in hundredths)	0.38%		0.38%
Agency Securities [Member] | Borrowings With Maturities Of 30 Days Or Less [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Collateral Carrying Amount	10,401,080		12,169,534
Accrued Interest Receivable	24,045		28,195
Borrowings Outstanding	9,878,889		11,578,211
Average Borrowing Rates (in hundredths)	0.35%		0.38%
Agency Securities [Member] | Borrowings With Maturities of 31 to 90 Days [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Collateral Carrying Amount	1,205,570		951,966
Accrued Interest Receivable	2,248		2,068
Borrowings Outstanding	1,150,924		902,432
Average Borrowing Rates (in hundredths)	0.35%		0.38%
Agency Securities [Member] | Borrowings With Maturities Greater Than 90 Days [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Collateral Carrying Amount	1,874,892
Accrued Interest Receivable	4,640
Borrowings Outstanding	1,775,000
Average Borrowing Rates (in hundredths)	0.56%
Collateral For Structured Financings [Member] | Similar Borrowings [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Collateral Carrying Amount	2,030	[1]	2,257	[1]
Accrued Interest Receivable	0	[1]	0	[1]
Borrowings Outstanding	$2,030	[1]	$2,257	[1]
Average Borrowing Rates (in hundredths)	8.11%	[1]	8.09%	[1]
[1]	The maturity of structured financings is directly affected by prepayments on the related mortgage pass-through securities pledged as collateral and these financings are subject to redemption by the residual bondholders.

USE_OF_DERIVATIVE_FINANCIAL_IN2

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Schedule of Swap Agreements (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2010	Dec. 31, 2013
Notional Disclosures [Abstract]
Derivative instruments unrealized losses to be recognized	$12,200,000
Interest Rate SWAP Currently-Paying Contracts [Member]
Notional Disclosures [Abstract]
Notional Amount	7,200,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.51%
Derivative, average remaining maturity	12 months
Interest Rate SWAP Currently-Paying Contracts [Member] | First Quarter 2015 [Member]
Notional Disclosures [Abstract]
Notional Amount	1,100,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.50%
Interest Rate SWAP Currently-Paying Contracts [Member] | Second Quarter 2015 [Member]
Notional Disclosures [Abstract]
Notional Amount	200,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.43%
Interest Rate SWAP Currently-Paying Contracts [Member] | Third Quarter 2015 [Member]
Notional Disclosures [Abstract]
Notional Amount	400,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.47%
Interest Rate SWAP Currently-Paying Contracts [Member] | Fourth Quarter 2015 [Member]
Notional Disclosures [Abstract]
Notional Amount	1,200,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.45%
Interest Rate SWAP Currently-Paying Contracts [Member] | First Quarter 2016 [Member]
Notional Disclosures [Abstract]
Notional Amount	1,700,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.51%
Interest Rate SWAP Currently-Paying Contracts [Member] | Second Quarter 2016 [Member]
Notional Disclosures [Abstract]
Notional Amount	1,100,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.47%
Interest Rate SWAP Currently-Paying Contracts [Member] | Third Quarter 2016 [Member]
Notional Disclosures [Abstract]
Notional Amount	700,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.56%
Interest Rate SWAP Currently-Paying Contracts [Member] | Fourth Quarter 2016 [Member]
Notional Disclosures [Abstract]
Notional Amount	800,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.66%
Interest Rate SWAP Forward-Starting Contracts [Member]
Notional Disclosures [Abstract]
Notional Amount	7,700,000,000
Derivative, average remaining maturity	12 months
Interest Rate SWAP Forward-Starting Contracts [Member] | First quarter 2017 [Member]
Notional Disclosures [Abstract]
Notional Amount	500,000,000
Average Fixed Rate Payment Requirement (in hundredths)	0.72%
Derivative, average remaining maturity	24 months
Interest Rate Swap Agreements [Member]
Derivative Instruments And Hedging Activities [Line Items]
SWAP agreement notional amount during period	2,300,000,000	100,000,000
SWAP agreement average interest rate during period (in hundredths)	0.62%	4.09%
Swap agreement notional amount expiring during period	1,300,000,000
SWAP agreement average interest rate expiring during period (in hundredths)	0.55%
Notional Disclosures [Abstract]
Payment term of LIBOR interest rate agreement	2 years	20 years
Accrued interest	9,500,000		5,500,000
Interest Rate Swap Expired One [Member]
Notional Disclosures [Abstract]
Payment term of LIBOR interest rate agreement	2 years
Interest Rate Swap Expired Two [Member]
Derivative Instruments And Hedging Activities [Line Items]
SWAP agreements notional amount beginning during the period	4,300,000,000
SWAP agreements average interest rate beginning during period (in hundredths)	0.54%
Repurchase Arrangements And Similar Borrowings [Member]
Notional Disclosures [Abstract]
Accrued interest	$6,100,000		$4,700,000

USE_OF_DERIVATIVE_FINANCIAL_IN3

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Balance Sheet and Income Statement Location (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Balance sheet-related [Abstract]
Interest rate swap agreements at fair value, net assets (liability)	($34,893)		($11,792)
Income statement-related [Abstract]
Amount of loss reclassified from Accumulated other comprehensive income related to the effective portion of active positions	22,055		16,914		19,882
Other Comprehensive Income (Loss) [Member]
Other comprehensive income related [Abstract]
Amount of gain (loss) recognized in Other comprehensive income (loss) (effective portion)	-41,059		9,320		-22,262
Interest Expense [Member]
Income statement-related [Abstract]
Amount of loss reclassified from Accumulated other comprehensive income related to the effective portion of active positions	-22,055		-16,914		-19,882
Amount of gain (loss) recognized (ineffective portion)	-473		24		-542
Increase in interest expense and decrease in Net income as a result of the use of Derivatives	-22,528	[1]	-16,890	[1]	-20,424	[1]
Other Assets [Member]
Balance sheet-related [Abstract]
Related net interest payable	-9,516	[2]	-5,493	[2]
Borrowings Under Repurchase Arrangements [Member] | Other Assets [Member]
Balance sheet-related [Abstract]
Interest rate swap agreements in a gain position (an asset)	1,657	[3]	1,094	[3]
Interest rate swap agreements in a loss position (a liability)	-6,332	[3]	-11,304	[3]
Unsecured Borrowings [Member] | Other Assets [Member]
Balance sheet-related [Abstract]
Interest rate swap agreements in a gain position (an asset)	0	[3]	3,911	[3]
Interest rate swap agreements in a loss position (a liability)	($20,702)	[3]	$0	[3]
[1]	Included in Interest expense: Repurchase arrangements and similar borrowings on the face of the Statements of Income.
[2]	Included in "Accounts payable and accrued expenses" on the face of the Balance Sheets.
[3]	The fair value of Derivatives with realized and unrealized gains are aggregated and recorded as an asset on the face of the Balance Sheets separately from the fair value of Derivatives with realized and unrealized losses that are recorded as a liability. The amount of unrealized losses scheduled to be recognized in the Statements of Income over the next twelve months primarily in the form of fixed-rate swap payments in excess of current market rates totaled $12.2 million at December 31, 2014.

USE_OF_DERIVATIVE_FINANCIAL_IN4

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Offsetting Assets (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Offsetting of derivative assets [Abstract]
Gross Amounts of Recognized Assets	$1,657		$5,005
Net Amounts of Assets Presented in the Balance Sheet	-34,893		-11,792
Cash Collateral Received	53,139		25,502
Offsetting Derivatives Assets [Member] | Counterparty 1 [Member]
Offsetting of derivative assets [Abstract]
Gross Amounts of Recognized Assets			3,911
Gross Amounts Offset in the Balance Sheet			0
Net Amounts of Assets Presented in the Balance Sheet			3,911
Financial Instruments			-3,911	[1]
Cash Collateral Received			0	[1]
Net Amount			0
Offsetting Derivatives Assets [Member] | Counterparty 2 [Member]
Offsetting of derivative assets [Abstract]
Gross Amounts of Recognized Assets	0		634
Gross Amounts Offset in the Balance Sheet	95		0
Net Amounts of Assets Presented in the Balance Sheet	95		634
Financial Instruments	-95	[1]	-634	[1]
Cash Collateral Received	0	[1]	0	[1]
Net Amount	0		0
Offsetting Derivatives Assets [Member] | Counterparty 4 [Member]
Offsetting of derivative assets [Abstract]
Gross Amounts of Recognized Assets	1,128		460
Gross Amounts Offset in the Balance Sheet	434		0
Net Amounts of Assets Presented in the Balance Sheet	1,562		460
Financial Instruments	-1,562	[1]	-460	[1]
Cash Collateral Received	0	[1]	0	[1]
Net Amount	0		0
Offsetting Derivatives Assets [Member] | Derivative Counterparties [Member]
Offsetting of derivative assets [Abstract]
Gross Amounts of Recognized Assets	1,128		5,005
Gross Amounts Offset in the Balance Sheet	529		0
Net Amounts of Assets Presented in the Balance Sheet	1,657		5,005
Financial Instruments	-1,657	[1]	-5,005	[1]
Cash Collateral Received	0	[1]	0	[1]
Net Amount	$0		$0
[1]	Amounts presented are limited to recognized liabilities and cash collateral received associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.

USE_OF_DERIVATIVE_FINANCIAL_IN5

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT, Offsetting Liabilities (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	$27,034		$11,304
Offsetting Financial Liabilities and Derivative Liabilities [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	12,848,968	[1]	12,504,401	[1]
Gross Amounts Offset in the Balance Sheet	529		0
Net Amounts of Liabilities Presented in the Balance Sheet	12,849,497	[2]	12,504,401	[2]
Financial Instruments	-12,814,604	[3]	-12,492,609	[3]
Cash Collateral Pledged	-34,893	[3]	-11,792	[3]
Net Amount	0		0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 1 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	24,533	[1]	6,002	[1]
Gross Amounts Offset in the Balance Sheet	0		0
Net Amounts of Liabilities Presented in the Balance Sheet	24,533	[2]	6,002	[2]
Financial Instruments	0	[3]	-3,911	[3]
Cash Collateral Pledged	-24,533	[3]	-2,091	[3]
Net Amount	0		0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 2 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	4,042	[1]	6,352	[1]
Gross Amounts Offset in the Balance Sheet	95		0
Net Amounts of Liabilities Presented in the Balance Sheet	4,137	[2]	6,352	[2]
Financial Instruments	-95	[3]	-634	[3]
Cash Collateral Pledged	-4,042	[3]	-5,718	[3]
Net Amount	0		0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 3 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	736	[1]	1,581	[1]
Gross Amounts Offset in the Balance Sheet	0		0
Net Amounts of Liabilities Presented in the Balance Sheet	736	[2]	1,581	[2]
Financial Instruments	0	[3]	0	[3]
Cash Collateral Pledged	-736	[3]	-1,581	[3]
Net Amount	0		0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 4 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	6,710	[1]	2,862	[1]
Gross Amounts Offset in the Balance Sheet	434		0
Net Amounts of Liabilities Presented in the Balance Sheet	7,144	[2]	2,862	[2]
Financial Instruments	-1,562	[3]	-460	[3]
Cash Collateral Pledged	-5,582	[3]	-2,402	[3]
Net Amount	0		0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Derivative Counterparties [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	36,021	[1]	16,797	[1]
Gross Amounts Offset in the Balance Sheet	529		0
Net Amounts of Liabilities Presented in the Balance Sheet	36,550	[2]	16,797	[2]
Financial Instruments	-1,657	[3]	-5,005	[3]
Cash Collateral Pledged	-34,893	[3]	-11,792	[3]
Repurchase Arrangements and Similar Borrowings [Member] | Offsetting Financial Liabilities and Derivative Liabilities [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	12,812,947	[1]	12,487,604	[1]
Gross Amounts Offset in the Balance Sheet	0		0
Net Amounts of Liabilities Presented in the Balance Sheet	12,812,947	[2]	12,487,604	[2]
Financial Instruments	-12,812,947	[3]	-12,487,604	[3]
Cash Collateral Pledged	0	[3]	0	[3]
Net Amount	$0		$0
[1]	Amounts include accrued interest of $9.5 million and $5.5 million on interest rate swap agreements and $6.1 million and $4.7 million on repurchase arrangements and similar borrowings, included in "Accounts payable and accrued expenses" on the face of the Balance Sheets as of December 31, 2014 and December 31, 2013, respectively.
[2]	Amounts presented are limited to recognized liabilities and cash collateral received associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.
[3]	Amounts presented are limited to recognized assets and collateral pledged associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.

USE_OF_DERIVATIVE_FINANCIAL_IN6

USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Changes in AOCI (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated other comprehensive income (loss) [Line Items]
Beginning Balance	$219,143	$293,910	$204,540
Other comprehensive income (loss) before reclassifications	-13,776	-91,681	69,488
Amounts reclassified from accumulated other comprehensive income	22,055	16,914	19,882
Other comprehensive income (loss)	8,279	-74,767	89,370
Ending Balance	227,422	219,143	293,910
Gains and Losses on Cash Flow Hedges [Member]
Accumulated other comprehensive income (loss) [Line Items]
Beginning Balance	-6,305	-32,539	-30,159
Other comprehensive income (loss) before reclassifications	-41,059	9,320	-22,262
Amounts reclassified from accumulated other comprehensive income	22,055	16,914	19,882
Other comprehensive income (loss)	-19,004	26,234	-2,380
Ending Balance	-25,309	-6,305	-32,539
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated other comprehensive income (loss) [Line Items]
Beginning Balance	225,448	326,449	234,699
Other comprehensive income (loss) before reclassifications	27,283	-101,001	91,750
Amounts reclassified from accumulated other comprehensive income	0	0	0
Other comprehensive income (loss)	27,283	-101,001	91,750
Ending Balance	$252,731	$225,448	$326,449

UNSECURED_BORROWINGS_Narrative

UNSECURED BORROWINGS - Narrative (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Junior subordinated notes maturity term	30 years
Issuance of common securities		$3.10
Remaining issue costs	2.1
Capstead Mortgage Trust I [Member]
Debt Instrument [Line Items]
Junior subordinated notes, maturity period	31-Oct-35
Capstead Mortgage Trust II [Member]
Debt Instrument [Line Items]
Junior subordinated notes, maturity period	31-Dec-35
Junior subordinated notes, earliest redemption option exercise date	15-Dec-15
Capstead Mortgage Trust III [Member]
Debt Instrument [Line Items]
Junior subordinated notes, maturity period	30-Sep-36
Junior subordinated notes, earliest redemption option exercise date	15-Sep-16
Interest paid on outstanding borrowings	8.4	8.6	8.6
Special-Purpose Statutory Trusts [Member]
Debt Instrument [Line Items]
Issuance of common securities		3.1
Proceeds from private placement of preferred securities	$100

UNSECURED_BORROWINGS_Schedule_

UNSECURED BORROWINGS - Schedule of Subordinated Note Balances and Related Weighted Average Interest Rate (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Debt Instrument [Line Items]
Borrowings Outstanding	100,000		$100,000
For Final 20 Years [Member]
Debt Instrument [Line Items]
Effective borrowing rate considering cash flow hedges	7.56%
Capstead Mortgage Trust I [Member]
Debt Instrument [Line Items]
Borrowings Outstanding	35,000		35,000
Average Rate (in hundredths)	8.31%	[1]	8.31%	[1]
Capstead Mortgage Trust II [Member]
Debt Instrument [Line Items]
Borrowings Outstanding	40,000		40,000
Average Rate (in hundredths)	8.46%	[1]	8.46%	[1]
Capstead Mortgage Trust III [Member]
Debt Instrument [Line Items]
Borrowings Outstanding	25,000		25,000
Average Rate (in hundredths)	8.78%	[1]	8.78%	[1]
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Borrowings Outstanding	100,000		$100,000
Average Rate (in hundredths)	8.49%	[1]	8.49%	[1]
[1]	The indicated weighted average rates have been in effect since issuance. After considering cash flow hedges that coincide with the floating rate terms of these borrowings that begin October 30, and December 15, 2015 for the notes associated with Capstead Mortgage Trusts I and II and September 15, 2016 for the notes associated with Capstead Mortgage Trust III, the effective borrowing rate will average 7.56% beginning September 15, 2016 through maturity, subject to certain adjustments for the effects of measured hedge ineffectiveness, if any.

DISCLOSURES_REGARDING_FAIR_VAL2

DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Narrative (Details) (Maximum [Member])	12 Months Ended
	Dec. 31, 2014
Maximum [Member]
Fair value, balance sheet grouping [Line Items]
Repurchase arrangements with initial terms in days	120 days

DISCLOSURES_REGARDING_FAIR_VAL3

DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Balance Sheet Location (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial assets [Abstract]
Residential mortgage loans	$13,908,104	$13,475,874
Interest rate swap agreements at fair value	1,657	5,005
Carrying Amount [Member]
Financial assets [Abstract]
Residential mortgage loans	4,909	6,898
Interest rate swap agreements at fair value	1,657	5,005
Financial liabilities [Abstract]
Repurchase arrangements with initial terms of greater than 120 days, Fair Value	2,128,517	36,299
Unsecured borrowings	100,000	100,000
Interest rate swap agreements	27,034	11,304
Fair Value [Member]
Financial assets [Abstract]
Residential mortgage loans	5,000	7,000
Interest rate swap agreements at fair value	1,657	5,005
Financial liabilities [Abstract]
Repurchase arrangements with initial terms of greater than 120 days, Fair Value	2,128,400	36,300
Unsecured borrowings	100,500	101,000
Interest rate swap agreements	$27,034	$11,304

DISCLOSURES_REGARDING_FAIR_VAL4

DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Fair Value and Related Disclosures for Debt Securities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Residential Mortgage Securities Classified as held-to-Maturity [Member]
Held-to-maturity securities disclosure [Abstract]
Held-to-maturities, Amortized Cost Basis	$3,663	$4,376
Held-to-maturities, Gross Unrealized Gains	124	211
Held-to-maturities, Gross Unrealized Losses	0	0
Held-to-maturities, Fair Value	3,787	4,587
Agency Securities Classified as Available-for-sale [Member] | Fannie Mae/Freddie Mac [Member]
Available-for-sale securities disclosure Items [Abstract]
Available-for-sale securities, Amortized Cost Basis	10,559,231	11,019,116
Available-for-sale securities, Gross Unrealized Gains	243,351	224,456
Available-for-sale securities, Gross Unrealized Losses	2,218	12,468
Available-for-sale securities, Fair Value	10,800,364	11,231,104
Agency Securities Classified as Available-for-sale [Member] | Ginnie Mae [Member]
Available-for-sale securities disclosure Items [Abstract]
Available-for-sale securities, Amortized Cost Basis	3,087,570	2,220,035
Available-for-sale securities, Gross Unrealized Gains	16,755	18,384
Available-for-sale securities, Gross Unrealized Losses	5,157	4,924
Available-for-sale securities, Fair Value	$3,099,168	$2,233,495

DISCLOSURES_REGARDING_FAIR_VAL5

DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Securities in Unrealized Loss Position (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Continuous unrealized loss position, fair value [Abstract]
One year or greater	$706,839	$39,030
Less than one year	1,095,724	2,857,724
Continuous unrealized loss position, Fair Value, Total	1,802,563	2,896,754
Continuous unrealized loss position, aggregate loss [Abstract]
One year or greater	5,320	380
Less than one year	2,055	17,012
Unrealized Losses, Total	$7,375	$17,392

INCOME_TAXES_Schedule_of_Effec

INCOME TAXES - Schedule of Effective Income Tax Rate Reconciliation (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
INCOME TAXES [Abstract]
Income taxes computed at the federal statutory rate	$49,287	$44,270	$57,269
Benefit of REIT status	-49,283	-44,270	-57,268
Income taxes computed on income of Capstead's sole taxable REIT subsidiary	4	0	1
Change in net deferred income tax assets	-4	1	-1
Other	0	-1	0
Income tax provision	$0	$0	$0

INCOME_TAXES_Narrative_Details

INCOME TAXES - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
INCOME TAXES [Abstract]
Income taxes paid	$0	$0	$0

INCOME_TAXES_Components_of_Def

INCOME TAXES - Components of Deferred Tax Assets and Liabilities (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
INCOME TAXES [Abstract]
Alternative minimum tax credit	$1,941	[1]	$1,942	[1]
Net operating loss carryforwards	58	[2]	60	[2]
Other	20		21
Deferred tax assets, gross, Total	2,019		2,023
Deferred income tax liabilities	0		0
Net deferred tax assets	2,019		2,023
Valuation allowance	2,019	[3]	2,023	[3]
Operating loss carryforwards subject to expiration amount	$3,500
Operating loss carryforwards, expiration date	31-Dec-19
[1]	Alternative minimum tax credit carryforwards can be utilized to offset payment of federal income taxes on future taxable income, if any, earned by this subsidiary, subject to certain limitations.
[2]	Excludes $3.5 million in remaining net operating loss carryforwards which expire beginning after 2019. To the extent these carryforwards are utilized in future periods, the benefit will reduce actual taxes payable.
[3]	Because this subsidiary is not expected to earn significant amounts of taxable income, related net deferred tax assets are fully reserved at December 31, 2014.

STOCKHOLDERS_EQUITY_Details

STOCKHOLDERS' EQUITY (Details) (USD $)	3 Months Ended	12 Months Ended			1 Months Ended	2 Months Ended
	Jan. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	31-May-13	Feb. 27, 2015
Stockholders' Equity [Line Items]
Redemption preference premiums paid		$0	$19,924,000	$0
Proceeds from issuance of common stock		0	0	142,035,000
Preferred equity shares capital		18,180,000	165,756,000	4,479,000
Common stock repurchase program	100,000,000
Shares repurchased (in shares)	3,600,000
Value of stock repurchased	42,400,000
Cumulative Redeemable Preferred Stock, Series E [Member]
Stockholders' Equity [Line Items]
Redeemable preferred stock, shares issued (in shares)					6,800,000
Redeemable preferred stock, face value					170,000,000
Preferred stock dividend rate (in hundredths)					7.50%
Redeemable preferred stock, liquidation preference per share (in dollars per share)					$25
Cash on hand used in capital transactions					42,700,000
Net proceeds					164,300,000
Convertible Preferred Stock [Member]
Stockholders' Equity [Line Items]
Cash used for redemption of preferred stock			207,000,000
Redemption preference premiums paid			19,900,000
Reduction in income per share (in dollars per share)			$0.21
Shares (in shares)				309,000
Additional shares issued (in shares)				309,000
Preferred equity shares capital				4,500,000
Continuous Offering Program [Member]
Stockholders' Equity [Line Items]
Shares (in shares)				10,500,000
Proceeds from issuance of common stock				142,000,000
Additional shares issued (in shares)				10,500,000
Continuous Offering Program [Member] | Cumulative Redeemable Preferred Stock, Series E [Member]
Stockholders' Equity [Line Items]
Shares (in shares)		757,000	61,000
Net Issue Price (In dollars per share)		$24.01	$23.78
Net proceeds		18,180,000	1,447,000
Additional shares issued (in shares)		757,000	61,000
Continuous Offering Program [Member] | Cumulative Redeemable Preferred Stock, Series E [Member] | Subsequent Event [Member]
Stockholders' Equity [Line Items]
Shares (in shares)						222,000
Net Issue Price (In dollars per share)						$24.65
Net proceeds						5,465,000
Additional shares issued (in shares)						222,000
Directors And Employees [Member]
Stockholders' Equity [Line Items]
Additions to common equity capital related to equity-based awards		$1,900,000	$1,800,000	$4,400,000

COMPENSATION_PROGRAMS_Other_Co

COMPENSATION PROGRAMS - Other Compensation Programs (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Programs [Line Items]
Short-term incentive compensation program accruals	$1,400,000
Annual incentive compensation expense	1,200,000	2,800,000	4,100,000
DER issued and outstanding (in shares)	654
Dividend Equivalent Rights Payable	222,000
DER expense for the period	889,000	811,000	914,000
Stock Options [Member]
Share Based Compensation Programs [Line Items]
Share awards contractual term	10 years
Options exercisable, weighted average remaining contractual term	3 years 6 months
Options exercisable, intrinsic value	26,000
Intrinsic value of option awards exercised	$67,000	$26,000	$620,000
Long-Term Equity-Based Awards [Member]
Share Based Compensation Programs [Line Items]
Issuance of common shares pursuant to future equity-based awards (in shares)	5,000,000
Common shares available for future issuance	4,927,763
Share awards contractual term	3 years
Share awards vesting period	3 years

COMPENSATION_PROGRAMS_Schedule

COMPENSATION PROGRAMS - Schedule of Restricted Stock Awards (Details) (USD $)	12 Months Ended	1 Months Ended	12 Months Ended	0 Months Ended		12 Months Ended	1 Months Ended
	Dec. 31, 2014	Jan. 31, 2014	Dec. 31, 2013	Jul. 31, 2014	Apr. 30, 2014	Dec. 31, 2012	Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)	72,237
Grant date fair value per share (in dollars per share)	$12.80
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Unvested stock awards outstanding at beginning of period (in shares)	528,931	528,931
Grants (in shares)	72,237
Vestings (in shares)	-164,587
Unvested stock awards outstanding at end of period (in shares)	436,581
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Unvested stock awards outstanding at beginning of year (in dollars per share)	$12.51	12.51
Grants (in dollars per share)	$12.80
Vestings (in dollars per share)	$13.23
Unvested stock awards outstanding at end of year (in dollars per share)	$12.29
Common stock dividend payable	$34,054,000		$30,872,000
Service-Based Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)	37,237	22,164	35,703
Grant date fair value per share (in dollars per share)	$12.47		$12.34
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)	37,237	22,164	35,703
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)	$12.47		$12.34
Service-Based Stock Awards [Member] | Director Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)				35,000	28,000
Grant date fair value per share (in dollars per share)				$13.16	$13.02
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)				35,000	28,000
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)				$13.16	$13.02
Stock Awards Activity [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)	114,423		121,026			67,599
Grant date fair value per share (in dollars per share)	$13.31		$12.01			$10.18
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)	114,423		121,026			67,599
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)	$13.31		$12.01			$10.18
Long term incentive compensation expense	1,500,000		1,800,000			1,900,000
Other general and administrative expense	315,000		387,000			362,000
Common stock dividend payable	1,400,000		1,200,000
Total of unrecognized compensation expense for unvested stock award	2,200,000
Compensation cost not yet recognized, period for recognition	1 year 6 months
Long Term Equity Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)			242,505
Grant date fair value per share (in dollars per share)	$7.21		$12.45
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)			242,505
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)	$7.21		$12.45
Long term incentive compensation expense			582,000
Common stock dividend payable	213,000		75,000
Total estimated compensation expense for restricted stock units	1,700,000		3,000,000
Long Term Equity Based Awards [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)							247,512
Grant date fair value per share (in dollars per share)							$8.83
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)							247,512
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)							$8.83
Total of unrecognized compensation expense for unvested stock award							$2,200,000
Long Term Equity Based Awards [Member] | February 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)	125,221
Grant date fair value per share (in dollars per share)	$12.58
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)	125,221
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)	$12.58
Long Term Equity Based Awards [Member] | January 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)	133,571
Grant date fair value per share (in dollars per share)	$12.17
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)	133,571
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)	$12.17
Long Term Equity Based Awards [Member] | January 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total original grants (in shares)	69,849
Grant date fair value per share (in dollars per share)	$11.67
Equity instruments other than options, nonvested, number of shares [Roll Forward]
Grants (in shares)	69,849
Equity instruments other than options, nonvested, weighted average grant date fair value [Abstract]
Grants (in dollars per share)	$11.67

COMPENSATION_PROGRAMS_Schedule1

COMPENSATION PROGRAMS - Schedule of Stock Option Award Activity (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
COMPENSATION PROGRAMS [Abstract]
Option awards outstanding at beginning of year (in shares)	77,500
Expirations (in shares)	-10,000
Exercises (in shares)	-27,500
Option awards outstanding at end of year (in shares)	40,000
Weighted Average Exercise Price, option awards outstanding at beginning of year (in dollars per share)	$11.75
Weighted Average Exercise Price, expirations (in dollars per share)	$14.41
Weighted Average Exercise Price, exercises (in dollars per share)	$10.63
Weighted Average Exercise Price, option awards outstanding at end of year (in dollars per share)	$11.86

COMPENSATION_PROGRAMS_Defined_

COMPENSATION PROGRAMS - Defined Contribution Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Abstract]
Defined contribution plan voluntary contribution based on compensation (in hundredths)	50.00%
Defined contribution plan, maximum annual contributions per employee (in hundredths)	6.00%
Defined contribution plan, employer matching contribution (in hundredths)	3.00%
Defined contribution plan, cost recognized	$258,000	$320,000	$406,000

QUARTERLY_RESULTS_UNAUDITED_Su

QUARTERLY RESULTS (UNAUDITED) - Summarized Quarterly Results of Operations (Details) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
QUARTERLY RESULTS (UNAUDITED) [Abstract]
Interest income on residential mortgage investments (before investment premium amortization)	$82,509		$82,146		$82,233		$81,733		$83,254		$85,674		$85,214		$86,867
Investment premium amortization	-26,159		-28,284		-25,141		-22,288		-24,800		-39,031		-33,642		-28,399		-101,872	-125,872	-96,677
Related interest expense	-18,107		-16,099		-15,542		-15,407		-15,392		-15,759		-16,749		-18,468		-65,155	-66,368	-69,101
Net interest income (expense)	38,243		37,763		41,550		44,038		43,062		30,884		34,823		40,000		153,421	140,355	178,781
Other interest income (expense)	-2,023	[1]	-2,044	[1]	-2,045	[1]	-2,061	[1]	-2,066	[1]	-2,074	[1]	-2,015	[1]	-2,010	[1]
Other revenue (expense)	-2,746		-3,328		-2,941		-3,586		-4,023		-4,108		-2,914		-3,072		-12,601	-14,117	-15,414
Net income	$33,474		$32,391		$36,564		$38,391		$36,973		$24,702		$29,894		$34,918		$140,820	$126,487	$163,626
Basic and diluted net income per common share	$0.31		$0.30		$0.35		$0.37		$0.35	[2]	$0.23	[2]	$0.04	[2]	$0.31	[2]	$1.33	$0.93	$1.50
Redemption preference premiums paid and other one-time effects of the preferred capital transactions (in dollars per share)													$0.23
[1]	Consists principally of interest on unsecured borrowings and is presented net of earnings of related statutory trusts. These affiliates were dissolved in December 2013.
[2]	Includes $0.23 associated with redemption preference premiums paid and other one-time effects of the second quarter's preferred capital transactions.