Significant Accounting Policies (Policy)	9 Months Ended
Significant Accounting Policies (Policy)	Sep. 30, 2012
Significant Accounting Policies [Abstract]
Basis Of Presentation	(A) Basis of Presentation: The Company's unaudited interim consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America for investment companies, ASC 946, Financial Services—Investment Companies ("ASC 946"), for interim financial information. ASC 946 requires, among other things, that investments be reported at fair value in the financial statements. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All inter-company balances and transactions have been eliminated. The preparation of consolidated financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Interim results are not necessarily indicative of the results that may be expected for the entire fiscal year. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2011.
Valuation	(B) Valuation: The Company applies ASC 820-10, Fair Value Measurement and Disclosures ("ASC 820-10"), to its holdings of financial instruments. ASC 820-10 establishes a three-level valuation hierarchy for disclosure of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The three levels are defined as follows: Level 1—inputs to the valuation methodology are observable and reflect quoted prices (unadjusted) for identical assets or liabilities in active markets, Level 2—inputs to the valuation methodology other than quoted prices included in Level 1 are observable for the asset or liability, either directly or indirectly, and Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement. A financial instrument's categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in these securities.
Securities Transactions And Investment Income	(C) Securities Transactions and Investment Income: Securities transactions are generally recorded on trade date. Realized and unrealized gains and losses are calculated based on identified cost. Interest income, which includes accretion of discounts and amortization of premiums on mortgage-backed securities, or "MBS," commercial mortgage loans, U.S. Treasury securities and securitized debt, is recognized over the life of the investment using the effective interest method. For purposes of determining the effective interest rate, management estimates the future expected cash flows of its investment holdings based on assumptions including, but not limited to, assumptions for future prepayment rates, default rates and loss severities (each of which may in turn incorporate various macro-economic assumptions, such as future housing prices). These assumptions are re-evaluated not less than quarterly and require the use of a significant amount of judgment. Principal write-offs are generally treated as realized losses.
Cash And Cash Equivalents	(D) Cash and Cash Equivalents: Cash and cash equivalents include amounts held in an interest bearing overnight account and money market funds. As of September 30, 2012 and December 31, 2011, all cash was held in an interest bearing account at the Bank of New York Mellon Corporation.
Financial Derivatives	(E) Financial Derivatives: The Company enters into various types of financial derivatives. The two major types utilized are swaps and futures. Swaps: The Company may enter into various types of swaps, including interest rate swaps, credit default swaps and total return swaps. The primary risk associated with the Company's interest rate swap activity is interest rate risk. The primary risk associated with the Company's total return swap activity has been equity market risk. The primary risk associated with the Company's credit default swaps is credit risk. The Company is subject to interest rate risk exposure in the normal course of pursuing its investment objectives. To help mitigate interest rate risk, the Company enters into interest rate swaps. Interest rate swaps are contractual agreements whereby one party pays a floating rate of interest on a notional principal amount and receives a fixed rate on the same notional principal, or vice versa, for a fixed period of time. Interest rate swaps change in value with movements in interest rates. The Company enters into credit default swaps. A credit default swap is a contract under which one party agrees to compensate another party for the financial loss associated with the occurrence of a "credit event" in relation to a "reference amount" or notional value of a credit obligation (usually a bond, loan or a basket of bonds or loans). The definition of a credit event often varies from contract to contract. A credit event may occur (i) when the underlying reference asset(s) fails to make scheduled principal or interest payments to its holders, (ii) with respect to credit default swaps referencing mortgage/asset-backed securities and indices, when the underlying reference obligation is downgraded below a certain rating level or (iii) with respect to credit default swaps referencing corporate entities and indices, upon the bankruptcy of the underlying reference obligor. The Company typically writes (sells) protection to take a "long" position or purchases (buys) protection to take a "short" position with respect to underlying reference assets or to hedge exposure to other investment holdings. The Company enters into total return swaps in order to take a "long" or "short" position with respect to an underlying referenced asset. The Company is subject to market price volatility of the underlying referenced asset. A total return swap involves commitments to pay interest in exchange for a market-linked return based on a notional value. To the extent that the total return of the security, group of securities or index underlying the transaction exceeds or falls short of the offsetting interest obligation, the Company will receive a payment from or make a payment to the counterparty. Swaps change in value with movements in interest rates or total return of the referenced securities. During the term of swap contracts, changes in value are recognized as unrealized gains or losses. When the contracts are terminated, the Company will realize a gain or loss equal to the difference between the proceeds from (or cost of) the closing transaction and the Company's basis in the contract, if any. Periodic payments or receipts required by swap agreements are recorded as unrealized gains or losses when accrued and realized gains or losses when received or paid. Upfront payments paid/received by the Company to open swap contracts are recorded as an asset and/or liability on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity and are recorded as a realized gain or loss on the termination date. The Company may be required to deliver or receive cash or securities as collateral upon entering into swap transactions. The Company's swap contracts are generally governed by International Swaps and Derivatives Association, or "ISDA," trading agreements, which are separately negotiated agreements with dealer counterparties. Changes in the relative value of the swap transactions may require the Company or the counterparty to post or receive additional collateral. Typically, a collateral payment or receipt is triggered based on the net change in the value of all contracts governed by a particular ISDA trading agreement. Collateral received from counterparties is included in Due to brokers on margin accounts on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. Collateral paid to counterparties is included in Deposits with dealers held as collateral on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. Entering into swap contracts involves market risk in excess of amounts recorded on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. Futures Contracts: A futures contract is an agreement between two parties to buy and sell a financial instrument for a set price on a future date. The Company enters into Eurodollar futures contracts to hedge its interest rate risk. Initial margin deposits are made upon entering into futures contracts and can be either cash or securities. During the period the futures contract is open, changes in the value of the contract are recognized as unrealized gains or losses by marking to market on a daily basis to reflect the market value of the contract at the end of each day's trading. Variation margin payments are made or received periodically, depending upon whether unrealized gains or losses are incurred. When the contract is closed, the Company records a realized gain or loss equal to the difference between the proceeds of the closing transaction and the Company's basis in the contract. Derivative instruments disclosed on the Consolidated Condensed Schedule of Investments include: credit default swaps on asset-backed securities, credit default swaps on asset-backed indices, credit default swaps on corporate bond indices, interest rate swaps, total return swaps and Eurodollar futures contracts. Swap assets are included in Financial derivatives—assets at fair value on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. Swap liabilities are included in Financial derivatives—liabilities at fair value on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. In addition, swap contracts are summarized by type on the Consolidated Condensed Schedule of Investments. Unrealized appreciation on futures contracts is included in Financial derivatives—assets at fair value on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. Unrealized depreciation on futures contracts is included in Financial derivatives—liabilities at fair value on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. For interest rate swaps, total return swaps, credit default swaps and futures, notional values reflected on the Consolidated Condensed Schedule of Investments represent approximately 110%, 100%, 90% and 69%, respectively, of average monthly notional values of each such category outstanding during the nine month period ended September 30, 2012. For total return swaps, interest rate swaps, credit default swaps and futures, notional values reflected on the Consolidated Condensed Schedule of Investments represent approximately 354%, 111%, 92% and 65%, respectively, of average monthly notional values of each such category outstanding during the year ended December 31, 2011. The Company uses average monthly notional values outstanding to indicate the volume of activity with respect to these instruments.
Investments Sold Short	(F) Investments Sold Short: When the Company sells securities short, it typically satisfies its security delivery settlement obligation by obtaining the security sold from the same or a different counterparty via repurchase agreement. The Company generally is required to deliver cash or securities as collateral to the repurchase agreement counterparty. The amount by which the market value of the obligation falls short of or exceeds the proceeds from the short sale is treated as an unrealized gain or loss, respectively. A realized gain or loss will be recognized upon the termination of a short sale if the market price is less or greater than the proceeds originally received.
Reverse Repurchase Agreements And Repurchase Agreements	(G) Reverse Repurchase Agreements and Repurchase Agreements: The Company enters into reverse repurchase agreements with third-party broker-dealers whereby it sells securities under agreements to be repurchased at an agreed-upon price and date. Interest on the value of repurchase and reverse repurchase agreements issued and outstanding is based upon competitive market rates at the time of issuance. The Company accounts for reverse repurchase agreements as collateralized borrowings. When the Company enters into a reverse repurchase agreement, the lender establishes and maintains an account containing cash and securities having a value not less than the repurchase price, including accrued interest, of the reverse repurchase agreement. The Company enters into repurchase agreement transactions with third-party broker-dealers whereby it purchases securities under agreements to resell at an agreed-upon price and date. In general, securities received pursuant to repurchase agreements are delivered to counterparties of short sale transactions. Assets held pursuant to repurchase agreements are reflected as assets on the Consolidated Statement of Assets, Liabilities and Shareholders' Equity. Repurchase and reverse repurchase agreements that are conducted with the same counterparty may be reported on a net basis if they meet the requirements of ASC 210-20, Balance Sheet Offsetting. There are no repurchase and reverse repurchase agreements netted in the consolidated financial statements. Reverse repurchase agreements are carried at their contractual amounts, which the Company believes is the best estimate of fair value. At September 30, 2012, the Company's open reverse repurchase agreements had remaining terms that averaged 68 days and ranged from 2 to 180 days and had interest rates that averaged 1.07% and ranged from 0.31% to 2.80%. At September 30, 2012, approximately 64% of open reverse repurchase agreements were with three counterparties. At December 31, 2011, the Company's open reverse repurchase agreements had remaining terms that averaged 33 days and ranged from 3 to 180 days and had interest rates that averaged 0.82% and ranged from 0.08% to 2.56%. At December 31, 2011, approximately 73% of open reverse repurchase agreements were with four counterparties. The Company follows the provisions of ASC 860-20, Sales of Financial Assets, which requires an initial transfer of a financial asset and a repurchase financing that was entered into contemporaneously or in contemplation of the initial transfer to be evaluated as a linked transaction unless certain criteria are met, including that the transferred asset must be readily obtainable in the marketplace. As of September 30, 2012 the Company had no seller financed holdings.
Securitized Debt	(H) Securitized Debt: The Company entered into a resecuritization transaction in January 2012 which is accounted for as a collateralized borrowing. The asset contributed to the securitization was not derecognized but rather, the liability issued by the securitization was recorded to reflect the term financing of the re-securitized asset. Under ASC 820-10, the Company has elected to carry securitized debt at fair value. The asset subject to the resecuritization had a fair value of $2.4 million as of September 30, 2012 which is included on the Consolidated Condensed Schedule of Investments under Principal and Interest – Private Label Securities.
Purchased Options	(I) Purchased Options: The Company may enter into options primarily to help mitigate overall market risk. When the Company purchases an option, an amount equal to the premium paid is recorded as an asset and is subsequently marked-to-market. Premiums paid for purchasing options that expire unexercised are recognized on the expiration date as realized losses. If an option is exercised, the premium paid is subtracted from the proceeds of the sale or added to the cost of the purchase to determine whether the Company has realized a gain or loss on the related investment transaction. When the Company enters into a closing transaction, the Company will realize a gain or loss depending upon whether the amount from the closing transaction is greater or less than the premiums paid. The Company had no purchased options outstanding as of September 30, 2012 and December 31, 2011.
When-Issued/Delayed Delivery Securities	(J) When-Issued/Delayed Delivery Securities: The Company may purchase or sell securities on a when-issued or delayed delivery basis. Securities purchased or sold on a when-issued basis are traded for delivery beyond the normal settlement date at a stated price or yield, and no income accrues to the purchaser prior to settlement. Purchasing or selling securities on a when-issued or delayed delivery basis involves the risk that the market price or yield at the time of settlement may be lower or higher than the agreed-upon price or yield, in which case a realized loss may be incurred. The Company transacts in the forward settling To Be Announced MBS ("TBA") market. The Company typically does not take delivery of TBAs, but rather settles with its trading counterparties on a net basis. The market value of the securities that the Company is required to purchase pursuant to a TBA transaction may decline below the agreed-upon purchase price. Conversely, the market value of the securities that the Company is required to sell pursuant to a TBA transaction may increase above the agreed upon sale price. As part of its TBA activities, the Company may "roll" its TBA positions, whereby the Company may sell (buy) securities for delivery (receipt) in an earlier month and simultaneously contract to repurchase (sell) similar, but not identical, securities at an agreed-upon price on a fixed date in a later month (with the later-month price typically lower than the earlier-month price). The Company accounts for its TBA transactions (including those related to TBA rolls) as purchases and sales. As of September 30, 2012, total assets included $33.7 million of TBAs as well as $441.8 million of receivable for securities sold relating to unsettled TBA sales. As of December 31, 2011, total assets included $32.0 million of TBAs as well as $443.7 million of receivable for securities sold relating to unsettled TBA sales. As of September 30, 2012, total liabilities included $443.2 million of TBAs sold short as well as $33.7 million of payable for securities purchased relating to unsettled TBA purchases. As of December 31, 2011, total liabilities included $446.7 million of TBAs sold short as well as $32.5 million of payable for securities purchased relating to unsettled TBA purchases. On a net basis, as of September 30, 2012, the Company held a net short position in TBAs of $409.5 million while at December 31, 2011, the Company held a net short position in TBAs of $414.7 million.
Offering Costs/Placement Fees	(K) Offering Costs/Placement Fees: Offering costs and placement fees are charged against shareholders' equity.
LTIP Units	(L) LTIP Units:Long term incentive plan units ("LTIP units") have been issued to the Company's dedicated personnel and independent directors as well as the Manager. Costs associated with LTIP units issued to dedicated personnel and independent directors are amortized over the vesting period in accordance with ASC 718-10, Compensation—Stock Compensation. Costs associated with LTIP units issued to the Manager are amortized over the vesting period in accordance with ASC 505-50, Equity-Based Payments to Non-Employees. The vesting period for units issued to dedicated personnel and independent directors under the Ellington Incentive Plan for Individuals (the "Individual LTIP") is typically one year. The vesting period for units issued to the Manager under the Ellington Incentive Plan for Entities (the "Manager LTIP") occurred over a three year period that ended in August 2010. The cost of the Manager LTIP units fluctuated with the price per share until the vesting date, whereas the cost of the Individual LTIP units is based on the price per share at the initial grant date.
Dividends	(M) Dividends: Dividends payable are recorded in the consolidated financial statements on the ex-dividend date. Dividends are declared and paid on a quarterly basis in arrears.
Shares Repurchased	(N) Shares Repurchased: Common shares that are repurchased by the Company subsequent to issuance decrease total number of shares outstanding and issued.
Earnings Per Share ("EPS")	(O) Earnings Per Share ("EPS"): Basic EPS is computed using the two class method by dividing net increase (decrease) in shareholders' equity resulting from operations after adjusting for the impact of long term incentive plan units deemed to be participating securities, by the weighted average number of common shares outstanding calculated excluding long term incentive plan units. Because the Company's long term incentive plan units are deemed to be participating securities and the Company has no other equity securities outstanding, basic and diluted EPS are the same. See Note 8 for EPS computations.
Income Taxes	(P) Income Taxes:The Company intends to be treated as a partnership for U.S. federal income tax purposes. In general, partnerships are not subject to entity-level tax on their income, but the income of a partnership is taxable to its owners on a flow-through basis. The Company follows the provisions of ASC 740-10, Income Taxes ("ASC 740-10"), which requires management to determine whether a tax position of the Company is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals, based on the technical merits of the position. The Company did not have any additions to its unrecognized tax benefits resulting from tax positions related either to the current period or to 2011, 2010, 2009 or 2008 (its open tax years), and no reductions resulting from tax positions of prior years or due to settlements, and thus had no unrecognized tax benefits since inception. The Company does not expect any change in unrecognized tax benefits within the next fiscal year. There were no amounts accrued for tax penalties or interest as of or during the periods presented in these consolidated financial statements. The Company may take positions with respect to certain tax issues which depend on legal interpretation of facts or applicable tax regulations. Should the relevant tax regulators successfully challenge any such positions, the Company might be found to have a tax liability that has not been recorded in the accompanying consolidated financial statements. Also, management's conclusions regarding ASC 740-10 may be subject to review and adjustment at a later date based on factors including, but not limited to, further implementation guidance from the Financial Accounting Standards Board ("FASB"), and ongoing analyses of tax laws, regulations and interpretations thereof.
Subsequent Events	(Q) Subsequent Events: The Company applies the provisions of ASC 855-10, Subsequent Events, in the preparation of its consolidated financial statements. This standard establishes general standards of accounting for and disclosure of events that occur after the balance sheet date but before financial statements are issued.
Recent Accounting Pronouncements	(R) Recent Accounting Pronouncements: On April 29, 2011, the FASB issued ASU No. 2011-03, Transfers and Servicing (Topic 860), Reconsideration of Effective Control for Repurchase Agreements ("ASU 2011-03"). This modifies the criteria for determining when repurchase agreements and other similar transactions would be accounted for as financings (secured borrowings/lending agreements) as opposed to sales (purchases) with commitments to repurchase (resell). ASU 2011-03 is effective prospectively for new transfers and existing transactions that are modified in the first interim or annual period beginning on or after December 15, 2011. The adoption of ASU 2011-03 did not have a material impact on the Company's consolidated financial statements. On May 12, 2011, the FASB issued ASU No. 2011-04, Fair Value Measurement (Topic 820): Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. Generally Accepted Accounting Principles ("U.S. GAAP") and International Financial Reporting Standards ("IFRS") ("ASU 2011-04"). The amendments are of two types: (i) those that clarify the FASB's intent about the application of existing fair value measurement and disclosure requirements and (ii) those that change a particular principle or requirement for measuring fair value or for disclosing information about fair value measurement. The amendments that change a particular principle or requirement for measuring fair value or disclosing information about fair value measurements relate to (i) measuring the fair value of the financial instruments that are managed within a portfolio; (ii) application of premium and discount in a fair value measurement; and (iii) additional disclosures about fair value measurements. The update is effective for interim and annual periods beginning after December 15, 2011. As a result of the adoption of this update, the Company has added disclosure to Note 3 about the significant unobservable inputs underlying its Level 3 assets and liabilities. In December 2011, the FASB issued ASU No. 2011-11, Disclosures about Offsetting Assets and Liabilities ("ASU 2011-11"). This amends ASU 210-20, Balance Sheet Offsetting, to require new disclosures about balance sheet offsetting for derivative and financial instruments which are offset on the Statement of Assets, Liabilities and Shareholders' Equity. The update requires disclosure of gross asset and liability amounts for financial instruments shown net on the Statement of Assets, Liabilities and Shareholders' Equity. ASU 2011-11 is effective for interim and annual periods beginning on or after January 1, 2013 and is to be applied retrospectively. The Company does not expect the adoption of ASU 2011-11 to have a material impact on its consolidated financial statements.